Co-reporter:Jiangsheng Xie, Kun Huang, Xuegong Yu, Zhengrui Yang, Ke Xiao, Yaping Qiang, Xiaodong Zhu, Lingbo Xu, Peng Wang, Can Cui, and Deren Yang
ACS Nano September 26, 2017 Volume 11(Issue 9) pp:9176-9176
Publication Date(Web):August 31, 2017
DOI:10.1021/acsnano.7b04070
Tin dioxide (SnO2) has been demonstrated as an effective electron-transporting layer (ETL) for attaining high-performance perovskite solar cells (PSCs). However, the numerous trap states in low-temperature solution processed SnO2 will reduce the PSCs performance and result in serious hysteresis. Here, we report a strategy to improve the electronic properties in SnO2 through a facile treatment of the films with adding a small amount of graphene quantum dots (GQDs). We demonstrate that the photogenerated electrons in GQDs can transfer to the conduction band of SnO2. The transferred electrons from the GQDs will effectively fill the electron traps as well as improve the conductivity of SnO2, which is beneficial for improving the electron extraction efficiency and reducing the recombination at the ETLs/perovskite interface. The device fabricated with SnO2:GQDs could reach an average power conversion efficiency (PCE) of 19.2 ± 1.0% and a highest steady-state PCE of 20.23% with very little hysteresis. Our study provides an effective way to enhance the performance of perovskite solar cells through improving the electronic properties of SnO2.Keywords: electron transfer; electron traps; graphene quantum dots; perovskite solar cells; tin dioxide;
Co-reporter:Zhenyi Ni, Lingling Ma, Sichao Du, Yang Xu, Meng Yuan, Hehai Fang, Zhen Wang, Mingsheng Xu, Dongsheng Li, Jianyi Yang, Weida Hu, Xiaodong Pi, and Deren Yang
ACS Nano October 24, 2017 Volume 11(Issue 10) pp:9854-9854
Publication Date(Web):September 18, 2017
DOI:10.1021/acsnano.7b03569
Highly sensitive photodetection even approaching the single-photon level is critical to many important applications. Graphene-based hybrid phototransistors are particularly promising for high-sensitivity photodetection because they have high photoconductive gain due to the high mobility of graphene. Given their remarkable optoelectronic properties and solution-based processing, colloidal quantum dots (QDs) have been preferentially used to fabricate graphene-based hybrid phototransistors. However, the resulting QD/graphene hybrid phototransistors face the challenge of extending the photodetection into the technologically important mid-infrared (MIR) region. Here, we demonstrate the highly sensitive MIR photodetection of QD/graphene hybrid phototransistors by using plasmonic silicon (Si) QDs doped with boron (B). The localized surface plasmon resonance (LSPR) of B-doped Si QDs enhances the MIR absorption of graphene. The electron-transition-based optical absorption of B-doped Si QDs in the ultraviolet (UV) to near-infrared (NIR) region additionally leads to photogating for graphene. The resulting UV-to-MIR ultrabroadband photodetection of our QD/graphene hybrid phototransistors features ultrahigh responsivity (up to ∼109 A/W), gain (up to ∼1012), and specific detectivity (up to ∼1013 Jones).Keywords: boron doping; graphene; localized surface plasmon resonance; mid-infrared; phototransistor; silicon quantum dots;
Co-reporter:Deren Yang;Xiaobo Chen;Xiaodong Pi
The Journal of Physical Chemistry C May 20, 2010 Volume 114(Issue 19) pp:8774-8781
Publication Date(Web):2017-2-22
DOI:10.1021/jp100632u
Ab initio methods based on density functional theory are employed to investigate the bonding of oxygen (O) at the oxide/nanocrystal (NC) interface after hydrogen (H)-passivated silicon (Si) NCs are oxidized. Besides the well-known quantum confinement effect, the type of O bonding and the oxidation state of Si at the oxide/NC interface are found to significantly affect the optical properties of oxidized Si NCs. After oxidation, the excitation energies of Si35 and Si66 increase, while those of Si87 and Si123 decrease. We show that oxidation-induced redshifts in the light emission from Si NCs do not always result from defective O such as doubly bonded O at the oxide/NC interface. When Si atoms at the oxide/NC interface are mainly in low oxidation states, backbond O at the interface per se results in the redshifts in the light emission from Si NCs. When Si atoms at the oxide/NC interface are mainly in high oxidation states, Si3+═O at the interface leads to the redshifts in the light emission from Si NCs. It is found that for Si NCs with perfect oxide/NC interface (i.e., O at the interface is all backbond O) the seriously weakened next-nearest-neighboring Si—Si of Si3+ readily breaks after excitation. At the oxide/NC interface, Si2+═O induced strong electronic localization and Si2+═O and Si3+═O induced reduction of interface polarization stabilize the geometry of oxidized Si NCs at the excited state. The electronic localization of severely stressed bridge O at the oxide/NC interface is relatively weak. This facilitates the breaking of nearest-neighboring Si−Si at the oxide/NC interface as oxidized Si NCs are excited.
Co-reporter:Jingshan S. Du, Jungwon Park, QHwan Kim, Wonho Jhe, Vinayak P. Dravid, Deren Yang, and David A. Weitz
The Journal of Physical Chemistry Letters December 7, 2017 Volume 8(Issue 23) pp:5853-5853
Publication Date(Web):November 17, 2017
DOI:10.1021/acs.jpclett.7b02875
Solid-state transformation between different materials is often accompanied by mechanical expansion and compression due to their volume change and structural evolution at interfaces. However, these two types of dynamics are usually difficult to monitor in the same time. In this work, we use in situ transmission electron microscopy to directly study the reduction transformation at the AgCl–Ag interface. Three stages of lattice fluctuations were identified and correlated to the structural evolution. During the steady state, a quasi-layered growth mode of Ag in both vertical and lateral directions were observed due to the confinement of AgCl lattices. The development of planar defects and depletion of AgCl are respectively associated with lattice compression and relaxation. Topography and structure of decomposing AgCl was further monitored by in situ scanning transmission electron microscopy. Silver species are suggested to originate from both the surface and the interior of AgCl, and be transported to the interface. Such mass transport may have enabled the steady state and lattice compression in this volume-shrinking transformation.
Co-reporter:Yaguang Zhang;Ning Du;Chengmao Xiao;Shali Wu;Yifan Chen;Yangfan Lin;Jinwei Jiang;Yuanhong He
RSC Advances (2011-Present) 2017 vol. 7(Issue 54) pp:33837-33842
Publication Date(Web):2017/07/04
DOI:10.1039/C7RA04364C
We report the synthesis of SiGe@C porous microparticles (PoSiGe@C) via the decomposition of Mg2Si/Mg2Ge composites, acid pickling and subsequent carbon coating processes, respectively. The content of Ge can be tuned by the initial ratio of Mg2Si and Mg2Ge in the composite. The as-synthesized PoSiGe@C has been used as the anode material of lithium-ion batteries, which shows an enhanced cyclic and rate performance compared to bare Si, PoSiGe as well as PoSi@C porous microparticles. Briefly, the PoSiGe@C delivers a good cycling stability with 70% capacity retention after 400 cycles and only 0.075% capacity loss per cycle at the current density of 0.8 A g−1. Furthermore, super rate capability is also expressed by the PoSiGe@C. The unique porous structure, and synergistic effect of Si and Ge, may lead to the inherent high lithium-ion diffusivity and electrical conductivity of Ge, and good volume alleviation, which results in the good electrochemical performance.
Co-reporter:Yaguang Zhang;Ning Du;Chengmao Xiao;Shali Wu;Yifan Chen;Yangfan Lin;Jinwei Jiang;Yuanhong He
RSC Advances (2011-Present) 2017 vol. 7(Issue 54) pp:33837-33842
Publication Date(Web):2017/07/04
DOI:10.1039/C7RA04364C
We report the synthesis of SiGe@C porous microparticles (PoSiGe@C) via the decomposition of Mg2Si/Mg2Ge composites, acid pickling and subsequent carbon coating processes, respectively. The content of Ge can be tuned by the initial ratio of Mg2Si and Mg2Ge in the composite. The as-synthesized PoSiGe@C has been used as the anode material of lithium-ion batteries, which shows an enhanced cyclic and rate performance compared to bare Si, PoSiGe as well as PoSi@C porous microparticles. Briefly, the PoSiGe@C delivers a good cycling stability with 70% capacity retention after 400 cycles and only 0.075% capacity loss per cycle at the current density of 0.8 A g−1. Furthermore, super rate capability is also expressed by the PoSiGe@C. The unique porous structure, and synergistic effect of Si and Ge, may lead to the inherent high lithium-ion diffusivity and electrical conductivity of Ge, and good volume alleviation, which results in the good electrochemical performance.
Co-reporter:Peng Dong, Rong Wang, Xuegong Yu, Lin Chen, Xiangyang Ma, Deren Yang
Superlattices and Microstructures 2017 Volume 107(Volume 107) pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.spmi.2017.04.005
•The formation of metastable vacancy-dioxygen (VO2) complex in silicon, with a structure of [VO + Oi] is quantitatively investigated, which has little been experimentally reported.•Combined with the evolution of interstitial oxygen and VO complex during annealing, the mechanisms for [VO + Oi] formation and VO annihilation have been discussed.We have quantitatively investigated the formation kinetics of metastable vacancy-dioxygen (VO2) complex in a structure of [VO + Oi], where a VO complex is trapped in a next-neighbor position to an interstitial oxygen atom (Oi). It is found that the VO annihilation is accompanied by the generation of metastable [VO + Oi] complex during annealing in the temperature range of 220–250 °C. The activation energy for [VO + Oi] generation appears at around 0.48 eV, which is much lower than the counterpart of stable VO2 complex. This indicates that the formation of [VO + Oi] complex originates from the reaction between VO and Oi. The ab initio calculations show that the formation energy of [VO + Oi] complex is larger than that of VO2 complex, which means that [VO + Oi] complex is thermodynamically unfavorable as compared to VO2 complex. However, the binding energy of [VO + Oi] complex is positive, indicating that [VO + Oi] complex is stable against decomposition of VO and Oi in silicon. It is believed that [VO + Oi] complex serves as the intermediate for VO to VO2 conversion.Download high-res image (292KB)Download full-size image
Co-reporter:Yaling Xiong;Wenying Ye;Wenlong Chen;Yiwen Wu;Qingfeng Xu;Yucong Yan;Hui Zhang;Jianbo Wu
RSC Advances (2011-Present) 2017 vol. 7(Issue 10) pp:5800-5806
Publication Date(Web):2017/01/16
DOI:10.1039/C6RA25900F
Metal nanodendrites composed of highly branched arms have received great attention as electrocatalysts owing to their reasonably large surface area and the potential existence of low-coordinated sites in high densities. Although significant progress has been made in the synthesis of bimetallic nanodendrites, few works involve a system consisting of Pd and Cu, particularly in the case of alloyed nanodendrites. Here, we report a facile and powerful approach for the synthesis of PdCu alloy nanodendrites with tunable composition through varying the molar ratio of the Pd and Cu salt precursors. The key to achieving PdCu alloy nanodendrites is the use of W(CO)6, which serves as a strong reducing agent. In addition, variation in the molar ratio of the precursors, from Pd rich to Cu rich, leads to shape evolution of the PdCu alloy, moving from a polyhedral to a dendritic nanostructure. This result indicates that galvanic replacement between a Cu rich alloy and a Pd precursor also plays an important role in the formation of PdCu alloy nanodendrites. When used as electrocatalysts for the methanol oxidation reaction (MOR), PdCu alloy nanodendrites exhibit remarkably enhanced catalytic properties relative to commercial Pd/C. Specifically, Pd35Cu65 alloy nanodendrites show the highest specific activity and mass activity for the MOR, 9.3 and 7.6 times higher than that of commercial Pd/C, respectively. This enhancement can be attributed to their dendritic structure and a possible bifunctional mechanism between Pd and Cu.
Co-reporter:Dongli Hu, Shuai Yuan, Xuegong Yu, Liang He, Yunfei Xu, Xueri Zhang, Deren Yang
Solar Energy Materials and Solar Cells 2017 Volume 171(Volume 171) pp:
Publication Date(Web):1 November 2017
DOI:10.1016/j.solmat.2017.06.035
•Silicon powder coating was brushed on crucible wall.•Small grains were formed at the ingot edge.•The diffusion of Fe from Si3N4 was obviously depressed.•The width of “red zone/ black edge” was well reduced.•The solar cell efficiency of edge bricks was improved.The high performance multicrystalline (HPMC) silicon material with the feature of small and uniform grains has already been widely adopted in photovoltaic industry nowadays. However, the HPMC silicon ingots still suffer a comparatively lower minority carrier lifetime at the ingot edges induced by Fe in-diffusion. Here, we have engineered the grain boundaries (GBs) to control the low carrier lifetime zone at the HPMC silicon ingot edges, based on the grain nucleation enhanced by silicon powder coating at the crucible walls. The resultant GBs with high density paralleling to the crucible walls can getter Fe impurity, and meanwhile become the barriers for Fe diffusion. Therefore, the detrimental effect of interstitial Fe impurity on the carrier lifetime of edge wafers is sufficiently reduced and the performance of corresponding solar cells is improved. The solar cells have a narrower distribution in the performance, which is beneficial for the stability and durability of solar cells and modules. This growth concept using GBs to control the behaviors of Fe diffused from the crucible walls is interesting for photovoltaic application.
Co-reporter:Yaguang Zhang, Ning Du, SiJia Zhu, Yifan Chen, Yangfan Lin, Shali Wu, Deren Yang
Electrochimica Acta 2017 Volume 252(Volume 252) pp:
Publication Date(Web):20 October 2017
DOI:10.1016/j.electacta.2017.08.038
We demonstrate the synthesis of porous Si in carbon cages (PoSi@CC) via the oxidation of magnesium silicide, coating of carbon layer and subsequent acid washing. Different from the traditional porous Si@C core-shell(PoSi@CS) structure, new structure and morphology of PoSi@CC are obtained, and better electrochemistry performance is expressed. As the anode materials of lithium-ion batteries, the PoSi@CC particles show a capacity of 864 mAhg−1 with 91.7% capacity retention after 100 cycles at the current density of 0.4 Ag−1. When the current density increases to 1.6 and 3.2 Ag−1, the capacity can be maintained at 590, 475 mAhg−1, respectively. The good cycling and rate performance can be attributed to the unique structures of the porous Si in carbon cages. The outer carbon layer can alleviate the pulverization and stabilize solid electrolyte interphase (SEI) film, while the enough space in the PoSi@CC particles can buffer the volume change during the charge/discharge process, which may be responsible for the enhanced electrochemical performance.
Co-reporter:Jiangsheng Xie;Xuegong Yu;Jiabin Huang;Xuan Sun;Yunhai Zhang;Zhengrui Yang;Ming Lei;Lingbo Xu;Zeguo Tang;Can Cui;Peng Wang
Advanced Science 2017 Volume 4(Issue 8) pp:
Publication Date(Web):2017/08/01
DOI:10.1002/advs.201700018
In this Communication, a self-organization method of [6,6]-phenyl-C61-butyric acid 2-((2-(dimethylamino)-ethyl) (methyl)amino)ethyl ester (PCBDAN) interlayer in between 6,6-phenyl C61-butyric acid methyl ester (PCBM) and indium tin oxide (ITO) has been proposed to improve the performance of N–I–P perovskite solar cells (PSCs). The introduction of self-organized PCBDAN interlayer can effectively reduce the work function of ITO and therefore eliminate the interface barrier between electron transport layer and electrode. It is beneficial for enhancing the charge extraction and decreasing the recombination loss at the interface. By employing this strategy, a highest power conversion efficiency of 18.1% has been obtained with almost free hysteresis. Furthermore, the N–I–P PSCs have excellent stability under UV-light soaking, which can maintain 85% of its original highest value after 240 h accelerated UV aging. This self-organization method for the formation of interlayer can not only simplify the fabrication process of low-cost PSCs, but also be compatible with the roll-to-roll device processing on flexible substrates.
Co-reporter:Zhengrui Yang, Jiangsheng Xie, V. Arivazhagan, Ke Xiao, Yaping Qiang, Kun Huang, Ming Hu, Can Cui, Xuegong Yu, Deren Yang
Nano Energy 2017 Volume 40(Volume 40) pp:
Publication Date(Web):1 October 2017
DOI:10.1016/j.nanoen.2017.08.008
•We demonstrate for the first time the utilization of GQDs as an additive to PCBM.•The device maintains ~80% of its PCE under continuous 300 h full spectrum sunlight.•GQDs: PCBM resulted in a high efficient (17.56%) PSC with negligible hysteresis.•All component layers are deposited at room temperature and treated below 100 °C.Organic-inorganic hybrid perovskite solar cells (PSCs) have triggered a great deal of research on organic electron transport layers, such as phenyl C61 butyric acid methyl ester (PCBM), due to their potential application as a strong contender in photovoltaic industry with simple fabrication process and low cost. However, the low electrical conductivity and electron mobility of PCBM hinder the promotion of PSCs. Here we report a successful case of graphene quantum dots (GQDs) doping into PCBM electron transport layer (ETL) of planar N-I-P PSCs, resulting in an obvious increase in PCBM conductivity together with the enhanced charge extraction and reduced the trap state density of perovskite films. A low doping ratio (0.5 wt%) would be efficient to boost the Voc, Jsc and FF, a PCE of 17.56% is achieved. More importantly, the light stability of PSCs with PCBM: GQDs was improved: the unpackaged cells can keep > 80% of the initial PCE under simulated sunlight with the full UV component present after 300 h, in contrast to the reference device that dropped < 50% during the same period of time.Download high-res image (196KB)Download full-size image
Co-reporter:Ting Yu;Feng Wang;Yang Xu;Lingling Ma;Xiaodong Pi
Advanced Materials 2016 Volume 28( Issue 24) pp:4912-4919
Publication Date(Web):
DOI:10.1002/adma.201506140
Co-reporter:Yucong Yan, Hao Shan, Ge Li, Fan Xiao, Yingying Jiang, Youyi Yan, Chuanhong Jin, Hui Zhang, Jianbo Wu, and Deren Yang
Nano Letters 2016 Volume 16(Issue 12) pp:7999-8004
Publication Date(Web):November 28, 2016
DOI:10.1021/acs.nanolett.6b04524
Pt-based multimetallic core–shell nanoplates have received great attention as advanced catalysts, but the synthesis is still challenging. Here we report the synthesis of multimetallic Pd@PtM (M = Ni, Rh, Ru) nanoplates including Pd@Pt nanoplates, in which Pt or Pt alloy shells with controlled thickness epitaxially grow on plate-like Pd seeds. The key to achieve high-quality Pt-based multimetallic nanoplates is in situ generation of CO through interfacial catalytic reactions associated with Pd nanoplates and benzyl alcohol. In addition, the accurate control in a trace amount of CO is also of great importance for conformal growth of multimetallic core–shell nanoplates. The Pd@PtNi nanoplates exhibit substantially improved activity and stability for methanol oxidation reaction (MOR) compared to the Pd@Pt nanoplates and commercial Pt catalysts due to the advantages arising from plate-like, core–shell, and alloy structures.Keywords: electrocatalysis; epitaxial growth; interfacial catalytic reactions; Multimetallic core−shell nanocrystals; nanoplates;
Co-reporter:Wenjia Zhao, Ning Du, Hui Zhang and Deren Yang
Nanoscale 2016 vol. 8(Issue 8) pp:4511-4519
Publication Date(Web):27 Oct 2015
DOI:10.1039/C5NR06120B
We report a novel material of Co–Li2O@Si core–shell nanowire array synthesized via the lithiation of pre-synthesized CoO@Si core–shell nanowire arrays during the first cycle. When the potential window versus lithium was controlled between 0.01–1.2 V, the coated Si shell could be electrochemically active, while the Co–Li2O nanowire core could function as a stable mechanical support and an efficient electron conducting pathway during the charge–discharge process. The Co–Li2O@Si core–shell nanowire array anodes exhibit good cyclic stability and high power capability compared to planar Si film electrodes.
Co-reporter:Zhenyi Ni;Xiaodong Pi;Shu Zhou;Tomohiro Nozaki;Bruno Gridier
Advanced Optical Materials 2016 Volume 4( Issue 5) pp:700-707
Publication Date(Web):
DOI:10.1002/adom.201500706
Hyperdoping silicon nanocrystals (Si NCs) is emerging as an effective means to obtain novel properties such as localized surface plasmon resonance (LSPR) from Si. Here it is shown that the physical properties and in particular the LSPR of boron (B)-hyperdoped Si NCs significantly change as the NC size decreases from 6.8 to 2.4 nm. While the largest Si NCs undergo a stronger reduction of the average lattice spacing upon doping with respect to the smallest ones, they suffer much less from disorder and show LSPR over a wider range of B concentration. As a result, by taking advantage of the tunability of the NC size and doping level, the LSPR energy can be changed, making attractive the development of novel Si structures and devices based on B-hyperdoped Si NCs.
Co-reporter:Yichao Wu, Shuai Yuan, Xuegong Yu, Xiaodong Qiu, Haiyan Zhu, Jing Qian, Deren Yang
Solar Energy Materials and Solar Cells 2016 Volume 154() pp:94-98
Publication Date(Web):September 2016
DOI:10.1016/j.solmat.2016.04.043
•C co-doping will deteriorate the initial performance of Si solar cells.•C co-doping can suppress the B-O complex formation in crystalline silicon.•The C co-doped Si solar cell has better performances after full LID.•The C co-doped Si solar cells with low LID can be practically used in industry.We have investigated the impact of carbon co-doping on the performance of boron–doped Czochralski-grown silicon solar cells. It is found that carbon co-doping will deteriorate the initial performance of Aluminium-back-surface-field solar cells before light-induced degradation (LID), owing to the enhancement effect on the formation of oxygen precipitation. However, carbon co-doping can effectively suppress the formation of boron-oxygen complexes in the solar cells, which becomes more significant with an increase of the carbon concentration. Therefore, the performance of carbon co-doped silicon solar cells is better than that of conventional silicon solar cells after LID. All these results are of great significance for the practical application of carbon co-doped silicon solar cells with low LID effect in photovoltaic industry.
Co-reporter:Hao Wu, Xueke Xia, Ning Du, Zhuohan Li, Bowen Sun, Yifan Chen, Deren Yang
Journal of Alloys and Compounds 2016 Volume 689() pp:56-62
Publication Date(Web):25 December 2016
DOI:10.1016/j.jallcom.2016.07.308
•CuLi2O@Si nanowall arrays were synthesized by lithiation of pre-synthesized CuO@Si nanowall arrays.•The CuLi2O@Si nanowall array electrodes show stable cycling and superior rate capabilities.•The voltage-control technique was integrated into the electrochemical testing procedure.Silicon is an attractive lithium-ion battery anode material that is held back by its poor cycling stability. Herein, we report the synthesis of a novel CuLi2O@Si core-shell nanowall array electrode by lithiation of pre-synthesized CuO@Si core-shell nanowall arrays during the first cycle. The phase-transition progress from CuO to CuLi2O was realized through an electrochemically driven reduction process based on our voltage-controlled technique. CuLi2O@Si core-shell nanowall arrays, the actual anode material after the first lithiation process, show a high reversible capacity (2421 mAh g−1 at 0.2 C) and enhanced rate capability compared with planar CuSi electrodes. The composition and robustness of the core-shell structure are confirmed by TEM characterization after 5 cycles. In addition, the electrochemical performance of CuLi2O@Si nanowall arrays with different sputtering times has been investigated and the cycling remains stable at much higher mass loading.
Co-reporter:Shuai Yuan, Xuegong Yu, Xin Gu, Yan Feng, Jinggang Lu, Deren Yang
Superlattices and Microstructures 2016 Volume 99() pp:158-164
Publication Date(Web):November 2016
DOI:10.1016/j.spmi.2016.03.021
•The concentration range of Al doping is 0.01–0.1 ppmw.•The keff of Al in Si is obtained as 0.0029•Solar cell performance degrades with the increase of Al concentration.•Al doping shows no light induced degradation effect.•The efficiency of Al doped cell is comparable to that of degraded B doped cell.The impact of Al doping with the concentrations in the range of 0.01–0.1 ppmw on the performance of silicon wafers and solar cells is studied. The effective segregation coefficient of impurity keff of Al in Si is obtained as 0.0029, which is calculated as 0.0027, supporting that Al should be totally ionized and occupy the substitutional sites in silicon and serve as the +1 dopant. It is found that the open-circuit voltages (Uoc), short-circuit currents (Isc) and photo-electrical conversion efficiency of the Al-containing solar cells decrease with the increase of Al concentrations because of Al-related deep level recombination centers. The average absolute efficiency of Al-doped silicon solar cells is 0.34% lower than that of Ga-doped-only cells, and the largest difference can be about 0.62%. Moreover, Al doped silicon solar cells show no light induced efficiency degradation, and the average efficiency maintains above 17.78%, which is comparable at the final state to that of normal B-doped silicon solar cells.
Co-reporter:Jian Zhao, Peng Dong, Jianjiang Zhao, Xiangyang Ma, Deren Yang
Superlattices and Microstructures 2016 Volume 99() pp:35-40
Publication Date(Web):November 2016
DOI:10.1016/j.spmi.2016.05.036
•Ge-doping suppresses oxygen precipitation in heavily B-doped silicon without RTP.•Ge-doping enhances oxygen precipitation in heavily B-doped silicon with prior RTP.•The morphology of oxygen precipitates are significantly affected by Ge co-doping.•The effect of Ge is supposed to be related to strain relief and point defects.We have investigated the impact of germanium (Ge) co-doping on oxygen precipitation (OP) in heavily boron (B)-doped Czochralski (CZ) silicon subjected to low-high two-step anneal without or with the prior high temperature rapid thermal process (RTP). Herein, the Ge concentration is one order of magnitude higher than the B concentration. It is found that the Ge co-doping exhibits the effect of suppression or enhancement on OP in the heavily B-doped CZ silicon without or with the prior RTP. In the case without the prior RTP, the compressive stress introduced by the Ge co-doping compensates the tensile stress arising from the B-doping, which is not beneficial for the growth of oxide precipitates. While, in the case with the prior RTP, the Ge co-doping increases the amount of vacancies introduced by the RTP and, moreover, may enable to generate more heterogeneous nucleation centers of oxide precipitates, thus leading to the enhanced OP in the heavily B-doped CZ silicon.
Co-reporter:Jiangsheng Xie, Xuegong Yu, Xuan Sun, Jiabin Huang, Yunhai Zhang, Ming Lei, Kun Huang, Dikai Xu, Zeguo Tang, Can Cui, Deren Yang
Nano Energy 2016 Volume 28() pp:330-337
Publication Date(Web):October 2016
DOI:10.1016/j.nanoen.2016.08.048
•A highest PCE>17.2% has been achieved for the PSCs with PCBDAN.•The devices with PCBDAN show higher performance.•The improved stability of PSCs is related to the hydrophobic PCBDAN.•PCBDAN can be used in the fabrication of high efficient and stable PSCs.The recent rapid rise in power conversion efficiencies (PCEs) of perovskite solar cells (PSCs) has attracted worldwide extensive attention. However, the PSC applications are limited by their poor stability due to perovskite degradation in moisture. We used a fullerene amine interlayer in planar PSCs to reduce the interface barrier between ETL and metal electrode and also resist the moisture. The utilization of fullerene amine interlayer allowed for the enhancement of PSCs' performance, showing a highest power conversion efficiency (PCE)>17.2% with negligible hysteresis. More importantly, the air stability of PSCs with fullerene amine was improved: the unpackaged devices stored in air can keep their high performance with no obvious PCE loss in 10% humidity and >90% of the initial PCE in 45% humidity after 20 days.Improved performance and air stability of planar perovskite solar cells via interfacial engineering using a fullerene amine interlayer.
Co-reporter:Mengyao Zhong, Dikai Xu, Xuegong Yu, Kun Huang, Xuemei Liu, Yiming Qu, Yang Xu, Deren Yang
Nano Energy 2016 Volume 28() pp:12-18
Publication Date(Web):October 2016
DOI:10.1016/j.nanoen.2016.08.031
•We fabricated metal/insulator/semiconductor (MIS) solar cells with a structure of Gr/FG/Si.•Underside p-type Gr doping was obtained in the Gr/FG heterostructure.•One-step approach for doping and interface engineering of the Gr/Si solar cells was realized.•Performance of Gr/FG/Si solar cell was further enhanced by applying a temporary voltage bias.•PCE of 7.52% and 13.38% were achieved for the pristine Gr/FG/Si solar cell and after AR technique and chemical doping.One-step approach for doping and interface engineering of the Gr/Si solar cells was realized by using the fluorographene(FG) as an insulator interlayer. Metal/insulator/semiconductor (MIS) like solar cells with a structure of Gr/FG/Si were composed. The F atoms of FG serve as electron acceptors and yield p-type doping, which is beneficial for improving the Schottky barrier. The carrier recombination of the solar cell can be effectively suppressed by the employment of the FG interlayer and the PCE of the solar cell increased from 3.17% to 7.52%. More interestingly, the performance of Gr/FG/Si solar cell can be further enhanced by applying a temporary voltage bias, which was likely associated with rotation of the C―F bonds or/and enhancement of the Gr/FG coupling in electrical field. A PCE up to 13.38% was achieved by combining the AR technology and chemical doping from the top-side of the Gr.
Co-reporter:Shuangyi Zhao, Xiaodong Pi, Clément Mercier, Zhongcheng Yuan, Baoquan Sun, Deren Yang
Nano Energy 2016 Volume 26() pp:305-312
Publication Date(Web):August 2016
DOI:10.1016/j.nanoen.2016.05.040
•Si nanocrystals (NCs) are added into the classical P3HT:PCBM organic solar cells.•The power conversion efficiency may increase by ~40% when Si NCs are added.•Si NCs improved solar cell absorption, structure and energy-level alignment.Inorganic/organic ternary hybrid structures are emerging as promising candidates for the fabrication of novel solar cells. As one of the most important inorganic solar cell material, silicon (Si) is worth careful exploration during the preparation of the hybrid structures. Here we incorporate the nanoscale form of Si, Si nanocrystals (NCs), into the classical bulk-heterojunction organic solar cells based on poly (3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM). It is found that the solar cell efficiency may increase by ~ 40% when ~ 5% of PCBM in the original P3HT:PCBM blend is replaced with Si NCs. The efficiency enhancement is enabled by the improved short-wavelength absorption, optimized film structure and cascade energy-level alignment.Incorporation of silicon nanocrystals (Si NCs) into the classical bulk-heterojunction organic solar cells based on P3HT and PCBM leads to ternary hybrid solar cells. The solar cell efficiency may increase by ~40% when ~5% of PCBM in the original P3HT: PCBM blend is replaced with Si NCs.
Co-reporter:Xuegong Yu, Lifei Yang, Qingmin Lv, Mingsheng Xu, Hongzheng Chen and Deren Yang
Nanoscale 2015 vol. 7(Issue 16) pp:7072-7077
Publication Date(Web):05 Jan 2015
DOI:10.1039/C4NR06677D
The graphene–silicon (Gr–Si) Schottky junction solar cell has been recognized as one of the most low-cost candidates in photovoltaics due to its simple fabrication process. However, the low Gr–Si Schottky barrier height largely limits the power conversion efficiency of Gr–Si solar cells. Here, we demonstrate that electric field doping can be used to tune the work function of a Gr film and therefore improve the photovoltaic performance of the Gr–Si solar cell effectively. The electric field doping effects can be achieved either by connecting the Gr–Si solar cell to an external power supply or by polarizing a ferroelectric polymer layer integrated in the Gr–Si solar cell. Exploration of both of the device architecture designs showed that the power conversion efficiency of Gr–Si solar cells is more than twice of the control Gr–Si solar cells. Our study opens a new avenue for improving the performance of Gr–Si solar cells.
Co-reporter:Lifei Yang, Xuegong Yu, Weidan Hu, Xiaolei Wu, Yan Zhao, and Deren Yang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 7) pp:4135
Publication Date(Web):February 2, 2015
DOI:10.1021/am508211e
Graphene–silicon (Gr-Si) heterojunction solar cells have been recognized as one of the most low-cost candidates in photovoltaics due to its simple fabrication process. However, the high sheet resistance of chemical vapor deposited (CVD) Gr films is still the most important limiting factor for the improvement of the power conversion efficiency of Gr-Si solar cells, especially in the case of large device-active area. In this work, we have fabricated a novel transparent conductive film by hybriding a monolayer Gr film with silver nanowires (AgNWs) network soldered by the graphene oxide (GO) flakes. This Gr-AgNWs hybrid film exhibits low sheet resistance and larger direct-current to optical conductivity ratio, quite suitable for solar cell fabrication. An efficiency of 8.68% has been achieved for the Gr-AgNWs-Si solar cell, in which the AgNWs network acts as buried contacts. Meanwhile, the Gr-AgNWs-Si solar cells have much better stability than the chemically doped Gr-Si solar cells. These results show a new route for the fabrication of high efficient and stable Gr-Si solar cells.Keywords: buried contact; graphene; silicon; silver nanowire; solar cell
Co-reporter:Xiaodong Pi, Zhenyi Ni, Yong Liu, Zhichao Ruan, Mingsheng Xu and Deren Yang
Physical Chemistry Chemical Physics 2015 vol. 17(Issue 6) pp:4146-4151
Publication Date(Web):22 Dec 2014
DOI:10.1039/C4CP05196C
When silicene is passivated by hydrogen, a bandgap occurs so that it becomes a semiconductor. Analogous to all the other semiconductors, doping is highly desired to realize the potential of hydrogen-passivated silicene (H-silicene). In the framework of density functional theory (DFT), we have studied the doping of H-silicene with boron (B) and phosphorus (P). The concentration of B or P ranges from 1.4% to 12.5%. It is found that the doping of B or P enables the indirect-bandgap H-silicene to be a semiconductor with a direct bandgap. With the increase of the concentration of B or P, both the valence band and the conduction band shift to lower energies, while the bandgap decreases. Both B- and P-doping lead to the decrease of the effective mass of holes and electrons in H-silicene. For both B- and P-doped H-silicene a subband absorption peak may appear, which blueshifts with the increase of the dopant concentration.
Co-reporter:Chengmao Xiao, Ning Du, Yifan Chen, Jingxue Yu, Wenjia Zhao and Deren Yang
RSC Advances 2015 vol. 5(Issue 77) pp:63056-63062
Publication Date(Web):10 Jul 2015
DOI:10.1039/C5RA08656F
We demonstrate the synthesis of Ge@C three-dimensional porous particles (Ge@C TPP) via the decomposition of magnesium germanide (Mg2Ge) and subsequent deposition of a carbon layer. Briefly, Ge TPP is first synthesized by the annealing of a Mg2Ge precursor in air and a subsequent acid pickling process. Then, the carbon layer is deposited onto the Ge TPP by the pyrolysis of acetylene to form Ge@C TPP. When used as anode materials in lithium-ion batteries, the Ge@C TPP shows higher reversible capacity and better cycling performance than bulk Ge and bare Ge TPP. It is believed that the porous and core–shell structures can accommodate the volume change, give more lithiation sites, and stabilize the structure during the charge/discharge process, which may be responsible for the enhanced performance.
Co-reporter:Xinhui Mu, Xuegong Yu, Dikai Xu, Xinlei Shen, Zhouhui Xia, Hang He, Haiyan Zhu, Jiangsheng Xie, Baoquan Sun, Deren Yang
Nano Energy 2015 Volume 16() pp:54-61
Publication Date(Web):September 2015
DOI:10.1016/j.nanoen.2015.06.015
•The selective emitter structure is self-generated in the PEDOT:PSS/silicon solar cell by introducing a thin WO3 interlayer.•The contact resistance between Ag electrodes and PEDOT:PSS film is largely reduced.•The open-circuit voltage of PEDOT:PSS/silicon solar cell is significantly improved.•The PCE of solar cell with a WO3 interlayer is 11.5% higher than that of the reference ones.Organic/silicon hybrid solar cell has recently received intensive interest due to its simple and low-cost fabrication process, which could be potentially used in photovoltaics. However, the efficiency of organic/silicon solar cell needs further improvement. Here, we have introduced a WO3 thin layer between the Ag front electrodes and poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)(PEDOT:PSS) film in the PEDOT:PSS/silicon solar cell to form a doping-free selective emitter (SE) structure. The carrier recombination is suppressed at the interface of silicon and electrodes, and meanwhile, the contact resistance between the Ag electrodes and PEDOT:PSS film is largely reduced. Therefore, the open-circuit voltage and fill factor of solar cell is significantly improved. As a result, the solar cell with a SE structure displays the power conversion efficiency (PCE) of 11.65%, which is much higher than the one without a WO3 thin layer. These results pave a new way for the fabrication of high efficiency organic/silicon hybrid solar cells.An 11.65% efficiency has been achieved for the PEDOT:PSS/silicon solar cell with doping-free selective emitter due to the introduction of a thin WO3 interlayer.
Co-reporter:Shu Zhou, Xiaodong Pi, Zhenyi Ni, Yi Ding, Yingying Jiang, Chuanhong Jin, Christophe Delerue, Deren Yang, and Tomohiro Nozaki
ACS Nano 2015 Volume 9(Issue 1) pp:378
Publication Date(Web):December 31, 2014
DOI:10.1021/nn505416r
Localized surface plasmon resonance (LSPR) of doped Si nanocrystals (NCs) is critical to the development of Si-based plasmonics. We now experimentally show that LSPR can be obtained from both B- and P-doped Si NCs in the mid-infrared region. Both experiments and calculations demonstrate that the Drude model can be used to describe the LSPR of Si NCs if the dielectric screening and carrier effective mass of Si NCs are considered. When the doping levels of B and P are similar, the LSPR energy of B-doped Si NCs is higher than that of P-doped Si NCs because B is more efficiently activated to produce free carriers than P in Si NCs. We find that the plasmonic coupling between Si NCs is effectively blocked by oxide at the NC surface. The LSPR quality factors of B- and P-doped Si NCs approach those of traditional noble metal NCs. We demonstrate that LSPR is an effective means to gain physical insights on the electronic properties of doped Si NCs. The current work on the model semiconductor NCs, i.e., Si NCs has important implication for the physical understanding and practical use of semiconductor NC plasmonics.Keywords: boron; localized surface plasmon resonance; nanocrystals; phosphorus; silicon;
Co-reporter:Dongli Hu, Shuai Yuan, Liang He, Hongrong Chen, Yuepeng Wan, Xuegong Yu, Deren Yang
Solar Energy Materials and Solar Cells 2015 140() pp: 121-125
Publication Date(Web):
DOI:10.1016/j.solmat.2015.03.027
Co-reporter:Wenjia Zhao, Ning Du, Chengmao Xiao, Hao Wu, Hui Zhang and Deren Yang
Journal of Materials Chemistry A 2014 vol. 2(Issue 34) pp:13949-13954
Publication Date(Web):02 Jul 2014
DOI:10.1039/C4TA03238A
We demonstrate the synthesis of Ag–Si core–shell nanowall arrays via a simple displacement reaction and subsequent RF-sputtering deposition. The displacement between the Cu substrate and Ag+ leads to Ag nanowall arrays with good substrate adhesion. The Ag nanowall arrays can function as a mechanical support and an efficient electron conducting pathway for Si anode materials. These Ag–Si core–shell nanowall arrays show a discharge capacity of >1500 mA h g−1 at a current density of 2100 mA g−1 after 400 cycles. The capacity fade from 2nd to 400th cycles is only 0.1% per cycle. Moreover, cycling performance can be retained when the thickness of the Si layer increases, clearly demonstrating the superior cycling performance of Ag–Si core–shell nanowall arrays. Considering the simple and large-scale synthesis of Ag–Si core–shell nanowall arrays, this work may facilitate the commercial application of Si anode materials for Li-ion batteries.
Co-reporter:Lifei Yang, Xuegong Yu, Mingsheng Xu, Hongzheng Chen and Deren Yang
Journal of Materials Chemistry A 2014 vol. 2(Issue 40) pp:16877-16883
Publication Date(Web):16 Jul 2014
DOI:10.1039/C4TA02216E
Graphene-on-silicon (Gr–Si) heterojunction solar cells have recently attracted significant attention as promising candidates for low-cost photovoltaic applications. However, the power conversion efficiency of Gr–Si solar cells is generally smaller than 4% without chemical doping treatments. It is mainly limited by the low work function of Gr and high density defect states at the Gr–Si interface. Here, we have reported a new structure of Gr–Si solar cells by introducing a graphene oxide (GO) interlayer to engineer the Gr–Si interface for improving device performance. It is found that the GO interlayer can effectively increase open circuit voltage and meanwhile suppress the interface recombination of solar cells. As a result, a maximum efficiency of 6.18% can be achieved for the Gr/GO/Si solar cells, which is a new record for the pristine monolayer Gr–Si solar cell reported to date. Further, it is clarified that the Gr/GO/Si solar cell is significantly more stable than the Gr–Si solar cell with chemical doping. These results show a new route for fabricating efficient and stable chemical-doping-free Gr–Si solar cells.
Co-reporter:Hao Wu, Ning Du, Jiazheng Wang, Hui Zhang, Deren Yang
Journal of Power Sources 2014 Volume 246() pp:198-203
Publication Date(Web):15 January 2014
DOI:10.1016/j.jpowsour.2013.07.063
•Fe3O4 layer was deposited on a Cu 3D porous current collector.•The porous Fe3O4 electrodes show superior cyclability and rate capabilities.•Enhanced performance is attributed to the advantages of the porous structure.This paper describes the synthesis of three-dimensionally porous Fe3O4 via template-assisted and subsequent electrochemical deposition methods. When used as anode materials of lithium–ion batteries, the porous Fe3O4 electrodes show better cyclability and enhanced rate capabilities compared to planar Fe3O4 electrodes. The superior performance can be attributed to improved electrical contact, fast electron transport and good strain accommodation of the porous electrodes. The effect of the thickness of the porous Fe3O4 electrodes on the lithium–ion battery performance has also been investigated.
Co-reporter:Yang Yang;Yunpeng Li;Canxing Wang;Chen Zhu;Chunyan Lv;Xiangyang Ma
Advanced Optical Materials 2014 Volume 2( Issue 3) pp:240-244
Publication Date(Web):
DOI:10.1002/adom.201300406
Co-reporter:Xiaodong Pi, Rong Wang, Deren Yang
Journal of Materials Science & Technology 2014 Volume 30(Issue 7) pp:639-643
Publication Date(Web):July 2014
DOI:10.1016/j.jmst.2014.01.012
As a leading surface modification approach, hydrosilylation enables freestanding silicon nanocrystals (Si NCs) to be well dispersed in a desired medium. Although hydrosilylation-induced organic layers at the NC surface may somehow retard the oxidation of Si NCs, oxidation eventually occurs to Si NCs after relatively long time exposure to air. We now investigated the oxidation of hydrosilylated Si NCs in the frame work of density functional theory (DFT). Three oxygen configurations that may be introduced by the oxidation of a Si NC are considered. It is found that a hydrosilylated Si NC is less prone to oxidation than a fully H-passivated Si NC in the point of view of thermodynamics. At the ground state, backbond oxygen (BBO) and hydroxyl (OH) hardly change the gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of a hydrosilylated Si NC. At the excited state, the decrease in the HOMO–LUMO gap induced by the introduction of doubly bonded oxygen (DBO) is more significant than that induced by the introduction of BBO or OH. We have correlated the changes in the optical absorption (emission) of a hydrosilylated Si NC after oxidation to those of the HOMO–LUMO gap at the ground state (excited state).
Co-reporter:Ning Du, Yifan Chen, Chuanxin Zhai, Hui Zhang and Deren Yang
Nanoscale 2013 vol. 5(Issue 11) pp:4744-4750
Publication Date(Web):20 Mar 2013
DOI:10.1039/C3NR00275F
We demonstrated the layer-by-layer synthesis of γ-Fe2O3@SnO2@C porous core–shell nanorods. FeOOH nanorods were first synthesized via a hydrothermal process, and acted as a template for subsequent layer-by-layer deposition. It was indicated that the electrostatic attraction between the charged species may play the key role in the formation of the core–shell nanostructures. When used as an anode material in lithium-ion batteries, γ-Fe2O3@SnO2@C porous core–shell nanorods showed high initial Coulombic efficiency, high reversible capacity, and good cycling and rate performances. The correlation between the structure, composition and electrochemical performance was also discussed.
Co-reporter:Dan Li, Lei Wang, Dongsheng Li, Ning Zhou, Zhiqiang Feng, Xiaoping Zhong, Deren Yang
Applied Surface Science 2013 Volume 264() pp:621-624
Publication Date(Web):1 January 2013
DOI:10.1016/j.apsusc.2012.10.079
Abstract
A simple process for nanotexturing on the emitter of silicon solar cells using catalyzed wet chemical etching by size-controlled silver nanoparticles was reported. A fine textured black surface was achieved to realize the low light reflectivity less than 5%. After screen printing and firing by the industrial standard fabrication protocol, we obtained the nanotextured Si solar cells with 15.7%-efficiency without any additional antireflection (AR) coating. This result suggests that the inexpensive metal-assisted wet chemical nanotexture method is prospective to be used in photovoltaic industry.
Co-reporter:Leifeng Chen, Lei Wang, Xuegong Yu, Shijun Zhang, Dan Li, Chen Xu, Lingsheng Zeng, Shu Zhou, Jianjing Zhao, Fan Guo, Liqin Hu, Deren Yang
Applied Surface Science 2013 Volume 265() pp:187-191
Publication Date(Web):15 January 2013
DOI:10.1016/j.apsusc.2012.10.164
Abstract
The overall process of field emission can be dominated by the contact resistance between the single wall carbon nanotubes (SWCNTs) and the substrate. In order to reduce the contact resistance, we present a wet chemical process of constructing Ag–SWCNTs hybrid nanostructure. Constructing Ag–SWCNTs emitters could improve the electrical contact by increasing the contact area between SWCNTs and substrate. Contact resistance is greatly reduced compared to that of pristine SWCNTs. Field emission properties of Ag–SWCNTs hybrid emitters including current density and emitting image are remarkably improved. Field emission properties based on the modified Fowler–Nordheim (F–N) equation are discussed. Our studies show that this method can enhance the field emission properties of the SWCNTs by improving the contact resistance and is a promising way for mass production of SWCNTs for field emission display.
Co-reporter:Xuegong Yu, Jiahe Chen, Xiangyang Ma, Deren Yang
Materials Science and Engineering: R: Reports 2013 Volume 74(1–2) pp:1-33
Publication Date(Web):January–February 2013
DOI:10.1016/j.mser.2013.01.002
Microelectronic devices with high integration level and functional complexity are always requiring larger diameter and more perfect Czochralski (CZ) silicon wafers. Therefore, the defects, playing the key role in the quality control of silicon materials, have to be well controlled during crystal growth and device fabrication. Co-doping nitrogen (N), germanium (Ge) or carbon (C) into CZ silicon to control defect dynamics and to change defect evolution, so-called “impurity engineering”, has been developed in recent years, and has been widely applied in the fabrication of higher quality CZ silicon used for microelectronics nowadays. This article is to present an overview of the current status of impurity engineering in CZ silicon, based on the co-doping technologies of N, Ge and C. The fundamental properties of these three co-dopants and their interaction with point defects in CZ silicon are firstly introduced. The bulk of the article is focused on the effects of co-dopants on the formation of oxygen precipitates related to internal gettering (IG) of devices for metal contaminants, and voids associated with the gate oxide integrity (GOI) of devices in CZ silicon. Finally, the improvement of CZ silicon mechanical strength by co-doping technology is described.
Co-reporter:Ning Du, Hui Zhang and Deren Yang
Nanoscale 2012 vol. 4(Issue 18) pp:5517-5526
Publication Date(Web):04 Jul 2012
DOI:10.1039/C2NR00025C
Assembly techniques are being intensely sought for preparing nanocomposites with tunable compositions and structures. Compared to other assembly techniques, the layer-by-layer (LBL) technique, which is based on the electrostatic attraction between oppositely charged species, provides a simple, versatile and powerful method to synthesize various types of one-dimensional (1D) hybrid nanostructures. In this review, we begin with the developments in the LBL synthesis of nanocomposites, with a focus on our recent results for synthesizing 1D hybrid nanostructures via LBL assembly. Compared to previous LBL processes, we conducted the in situ reaction on the surface of 1D nanostructures via electrostatic attraction between oppositely charged 1D nanostructures and ions in the solution in an attempt to produce 1D hybrid nanostructures. Moreover, these core–shell nanostructures can be transformed into nanotubes by the removal of the templates. The as-synthesized 1D hybrid nanostructures and nanotubes with tunable composition exhibited enhanced performance for various applications such as gas sensors, lithium-ion batteries and cellular imaging.
Co-reporter:Jiazheng Wang, Ning Du, Hui Zhang, Jingxue Yu, Deren Yang
Journal of Power Sources 2012 Volume 208() pp:434-439
Publication Date(Web):15 June 2012
DOI:10.1016/j.jpowsour.2012.02.039
We demonstrate the synthesis of new Cu–Si1−xGex core–shell nanowire array electrodes by directly depositing Si1−xGex layer on the surface of pre-synthesized Cu nanowire arrays via co-sputtering method. When used as anodes of lithium-ion batteries, the Cu–Si1−xGex (x = 0.4) nanowire array electrodes show excellent electrochemical performance in terms of cycle stability and rate capability, which is much better than that of planar electrodes. The improved performance can be attributed to the good strain accommodation, fast electron transport and good electrical contact of the nanowire array electrodes. The effect of Ge content and the thickness of alloy film on the electrochemical performance of the three-dimensional electrodes have also been investigated.Highlights► SiGe layer was deposited on the Cu nanowire arrays via a co-sputtering method. ► The Cu–SiGe 3D electrodes show improved performance as anode for Li-ion battery. ► Improved performance was attributed to the advantages of the electrodes’ structure.
Co-reporter:Rong Wang, Xiaodong Pi, and Deren Yang
The Journal of Physical Chemistry C 2012 Volume 116(Issue 36) pp:19434-19443
Publication Date(Web):August 13, 2012
DOI:10.1021/jp307785v
As a leading surface-modification approach, hydrosilylation is critical to the practical use of silicon nanocrystals (Si NCs). However, the effect of hydrosilylation-induced surface chemistry on the electronic and optical properties of Si NCs is rather limitedly understood. By means of first-principles calculation at 0 K we show thermodynamically favored surface bonding for hydrosilylation of 1.4 nm Si NCs and the relative reactivity of alkenes and alkynes. The optical properties of hydrosilylated Si NCs are elucidated on the basis of their energy-level schemes and radiative recombination rates. The chain length (up to C12) of ligands hardly affects the absorption and emission of Si NCs. The increase of the surface coverage (up to 29%) of ligands causes the absorption onset to slightly redshift, hardly rendering changes to the light emission from Si NCs. As an added advantage, hydrosilylation may lead to enhanced light emission from Si NCs. Radiative recombination is very sensitive to surface chemistry for Si NCs. Only the coexistence of C═C and functional groups at the NC surface significantly modifies the electronic structures and optical behavior of Si NCs.
Co-reporter:Xuegong Yu, Peng Wang, Xiaoqiang Li, Deren Yang
Solar Energy Materials and Solar Cells 2012 98() pp: 337-342
Publication Date(Web):
DOI:10.1016/j.solmat.2011.11.028
Co-reporter:Xiaodong Pi, Li Zhang, and Deren Yang
The Journal of Physical Chemistry C 2012 Volume 116(Issue 40) pp:21240-21243
Publication Date(Web):September 17, 2012
DOI:10.1021/jp307078g
Among all types of solar cells, multicrystalline silicon (Si) solar cells are the most widely produced. The enhancement of the efficiency of multicrystalline Si solar cells may help broaden the deployment of solar cells worldwide. Here we show that the efficiency of state-of-the-art commercially produced multicrystalline Si solar cells can be enhanced by a simple inkjet printing of Si-quantum-dot (Si-QD) ink at the solar cell surface. It is found that the efficiency enhancement results from both the down-shifting of Si QDs and the antireflection of porous Si-QD films at the solar cell surface. The current results demonstrate that Si-based nanotechnology can facilitate the continuous development of traditional Si solar cells.
Co-reporter:Xiaodong Pi, Xiaobo Chen, Yeshi Ma and Deren Yang
Nanoscale 2011 vol. 3(Issue 11) pp:4584-4588
Publication Date(Web):11 Oct 2011
DOI:10.1039/C1NR10940E
Silicon
nanocrystals (Si NCs) may be both unintentionally and intentionally doped with nitrogen (N) during their synthesis and processing. Since the importance of Si NCs largely originates from their remarkable optical properties, it is critical to understand the effect of N doping on the optical behavior of Si NCs. On the basis of theoretical calculations, we show that the doping of Si NCs with N most likely leads to the formation of paired interstitial N at the NC surface, which causes both the optical absorption and emission of Si NCs to redshift. But these redshifts are smaller than those induced by doubly bonded O at the NC surface. It is found that high radiative recombination rates can be reliably obtained for Si NCs with paired interstitial N at the NC surface. The current results not only help to understand the optical behavior of Si NCs synthesized and processed in N-containing environments, but also inspire intentional N doping as an additional means to control the optical properties of Si NCs.
Co-reporter:Chuanxin Zhai, Ning Du, Hui Zhang, Jingxue Yu, Ping Wu, Chengmao Xiao and Deren Yang
Nanoscale 2011 vol. 3(Issue 4) pp:1798-1801
Publication Date(Web):03 Mar 2011
DOI:10.1039/C0NR01008A
CoSn3
nanoparticles have been successfully assembled on noncovalently poly(diallyldimethylammonium chloride)-functionalized multiwalled carbon nanotubes (MWCNTs) via a chemical reduction method in a polyol system. The influences of the surface functionality and the reaction temperature on the synthesis of uniform CoSn3-MWCNTs nanohybrids have been investigated. The as-synthesized CoSn3-MWCNTs nanohybrids have been applied as anodes for lithium-ion batteries, and show better lithium storage performance compared to the bare CoSn3 nanoparticles and MWCNTs. The combining of MWCNTs that can hinder the agglomeration and enhance the electronic conductivity of the active materials is responsible for the enhanced cyclic performance.
Co-reporter:Ping Wu, Ning Du, Hui Zhang, Jingxue Yu, Yue Qi and Deren Yang
Nanoscale 2011 vol. 3(Issue 2) pp:746-750
Publication Date(Web):29 Nov 2010
DOI:10.1039/C0NR00716A
This paper reports the synthesis of carbon-coated SnO2 (SnO2–C) nanotubes through a simple glucose hydrothermal and subsequent carbonization approach by using Sn nanorods as sacrificial templates. The as-synthesized SnO2–C nanotubes have been applied as anode materials for lithium-ion batteries, which exhibit improved cyclic performance compared to pure SnO2 nanotubes. The hollow nanostructure, together with the carbon matrix which has good buffering effect and high electronic conductivity, can be responsible for the improved cyclic performance.
Co-reporter:Ning Du, Hongxuan Wu, Hui Zhang, Chuanxin Zhai, Ping Wu, Lei Wang and Deren Yang
Chemical Communications 2011 vol. 47(Issue 3) pp:1006-1008
Publication Date(Web):09 Nov 2010
DOI:10.1039/C0CC03498C
This study presents a large-scale synthesis of water-soluble sodium fluosilicate (Na2SiF6) nanowires, which serve as a versatile template for producing nanotubes.
Co-reporter:Yue Qi, Ning Du, Hui Zhang, Ping Wu, Deren Yang
Journal of Power Sources 2011 Volume 196(Issue 23) pp:10234-10239
Publication Date(Web):1 December 2011
DOI:10.1016/j.jpowsour.2011.08.085
This paper reports the synthesis of Co2SnO4@C core–shell nanostructures through a simple glucose hydrothermal and subsequent carbonization approach. The as-synthesized Co2SnO4@C core–shell nanostructures have been applied as anode materials for lithium-ion batteries, which exhibit improved cyclic performance compared to pure Co2SnO4 nanocrystals. The carbon matrix has good volume buffering effect and high electronic conductivity, which may be responsible for the improved cyclic performance.Highlights► Co2SnO4@C nanostructures have synthesized through a simple hydrothermal approach. ► The carbon layer has good buffering effect and high electronic conductivity. ► The composites show improved performance as anode for Li-ion batteries. ► The improved performance was attributed to the carbon buffering matrixes.
Co-reporter:Ning Du, Xin Fan, Jingxue Yu, Hui Zhang, Deren Yang
Electrochemistry Communications 2011 Volume 13(Issue 12) pp:1443-1446
Publication Date(Web):December 2011
DOI:10.1016/j.elecom.2011.09.017
We demonstrate the large-area synthesis of Ni3Si2-supported Si (Ni3Si2–Si) nanowires on the surface of a Ni foam via a simple and rich-yield chemical vapor deposition and subsequent rf-sputtering method. When used as an anode of Li-ion batteries, the Ni3Si2–Si nanowires show a high reversible capacity of ~ 1800 and ~1600 mA h g− 1 at a high current rate of 1C and 2C during 100 cycles, respectively. The good contact, adhesion and conductivity of Ni3Si2–Si nanowires with the current collectors during the charge–discharge process may be responsible for the good performance.Highlights► Large-area Ni3Si2–Si nanowires on Ni foam were synthesized. ► The Ni3Si2–Si nanowires show high-rate capacity as anode of Li-ion batteries. ► The high-rate capacity is due to the good contact, adhesion and conductivity.
Co-reporter:Ning Du ; Yanfang Xu ; Hui Zhang ; Jingxue Yu ; Chuanxin Zhai
Inorganic Chemistry 2011 Volume 50(Issue 8) pp:3320-3324
Publication Date(Web):March 11, 2011
DOI:10.1021/ic102129w
A simple microemulsion-based method has been developed to synthesize ZnCo2(C2O4)3 nanowires that can be transformed to porous ZnCo2O4 nanowires under annealing conditions. The morphology of porous ZnCo2O4 nanowires can be tuned by the initial ZnCo2(C2O4)3 nanowires and the annealing temperatures. The as-synthesized porous ZnCo2O4 nanowires have been applied as anode materials of Li-ion batteries, which show superior capacity and cycling performance. The porous one-dimensional (1D) nanostructures and large surface area are responsible for the superior performance. Moreover, it is indicated that porous ZnCo2O4 nanowires synthesized at low annealing temperature (500 °C) show larger capacity and better cycling performance than that prepared at high annealing temperature (700 °C), because of their higher porosity and larger surface area.
Co-reporter:Xin Gu, Xuegong Yu, Deren Yang
Separation and Purification Technology 2011 Volume 77(Issue 1) pp:33-39
Publication Date(Web):2 February 2011
DOI:10.1016/j.seppur.2010.11.016
Silicon solar cell is one of the cleanest and most potential renewable resources. However, the high cost of raw material is impeding the development of silicon solar cell. In this paper, we have investigated a purification process designed for low-cost solar grade silicon with Al–Si system, using a powder metallurgy technique. It is found that by modulating the external pressure and/or protection ambient, the alloying of Al–Si powder mixture is easily accomplished at a relatively lower temperature. The mechanism of Si products purified from the Al–Si melt has been discussed based on their morphological characterizations. The impurity contents of the purified Si products can be controlled at a very low level (∼3 ppmw). Meanwhile, the yield of the purified Si products using the powder metallurgy technique is clarified to be higher than that of the conventional Al–Si purification technique without external pressure or protecting ambient. The process is quite potential of providing low-cost solar grade silicon feedstock for photovoltaic industry.Graphical abstractResearch highlights▶ A low-cost solar grade silicon purification process is proposed. ▶ This process makes purification of silicon easily achieved at a lower temperature. ▶ The impurity content of purified silicon is very low. ▶ This process has better yield than the conventional process.
Co-reporter:Ping Wu, Ning Du, Jie Liu, Hui Zhang, Jingxue Yu, Deren Yang
Materials Research Bulletin 2011 46(12) pp: 2278-2282
Publication Date(Web):
DOI:10.1016/j.materresbull.2011.08.060
Co-reporter:Jiazheng Wang, Ning Du, Hui Zhang, Jingxue Yu, Deren Yang
Materials Research Bulletin 2011 46(12) pp: 2378-2384
Publication Date(Web):
DOI:10.1016/j.materresbull.2011.08.045
Co-reporter:Xiaodong Pi, Qing Li, Dongsheng Li, Deren Yang
Solar Energy Materials and Solar Cells 2011 95(10) pp: 2941-2945
Publication Date(Web):
DOI:10.1016/j.solmat.2011.06.010
Co-reporter:Ping Wu, Ning Du, Hui Zhang, Jingxue Yu, and Deren Yang
The Journal of Physical Chemistry C 2011 Volume 115(Issue 9) pp:3612-3620
Publication Date(Web):February 11, 2011
DOI:10.1021/jp1113653
This paper reports the synthesis of carbon-encapsulated Fe3O4, γ-Fe2O3, and Fe nanostructures using FeOOH as a precursor and carbon nanocapsules (CNCs) as nanoreactors via controllable thermal transformation processes. The magnetic property investigation reveals that the as-synthesized Fe3O4-CNCs, γ-Fe2O3-CNCs, and Fe-C nanostructures all exhibit ferromagnetic behavior with quite high saturation magnetizations. Moreover, the Fe3O4-CNCs with a controlled carbon coating are prepared and their comparative lithium storage properties are investigated. It is found that optimized Fe3O4-CNCs exhibit high capacity and good cycling performance.
Co-reporter:Jiazheng Wang ; Ning Du ; Hui Zhang ; Jingxue Yu
The Journal of Physical Chemistry C 2011 Volume 115(Issue 47) pp:23620-23624
Publication Date(Web):October 18, 2011
DOI:10.1021/jp206277a
Cu–Sn core–shell three-dimensional electrodes have been successfully synthesized by directly depositing metallic Sn on the surface of presynthesized Cu nanowire arrays. When used as an anode for lithium-ion batteries, the Cu–Sn three-dimensional electrode exhibits a high reversible capacity, a high initial Coulombic efficiency, a good rate capability, and an improved capacity retention. The effect of the thickness of the Sn layer on the Li-ion battery performance has also been investigated. The efficient buffering of the volume change, fast transport of electrons, and good contact to the current collector of the array structure may be responsible for the good cycling performance.
Co-reporter:Xiaodong Pi ; Xiaobo Chen
The Journal of Physical Chemistry C 2011 Volume 115(Issue 20) pp:9838-9843
Publication Date(Web):May 2, 2011
DOI:10.1021/jp111548b
First-principles study of boron (B)-doped silicon nanocrystals (Si NCs) at 0 K in the framework of density functional theory has been carried out. It is found that B prefers residing at the surface of Si NCs, similar to phosphorus (P). Different from P, B induces surface restructuring when B is one- or two-coordinated at the NC surface. B doping does not significantly change the bandgap of Si NCs, but in most cases B introduces deep energy levels in the bandgap of Si NCs. This explains the B-doping induced quenching of band-edge light emission usually observed in experiments. The negligible infrared absorption of B-doped Si NCs may result from the fact that only three-coordinated B is formed at the NC surface. The electronic transitions involving the energy levels induced by these three-coordinated B are not in the infrared range.
Co-reporter:Bingdi Chen, Hui Zhang, Chuanxin Zhai, Ning Du, Chen Sun, Jingwen Xue, Deren Yang, Hai Huang, Bo Zhang, Qiuping Xie and Yulian Wu
Journal of Materials Chemistry A 2010 vol. 20(Issue 44) pp:9895-9902
Publication Date(Web):14 Sep 2010
DOI:10.1039/C0JM00594K
We developed a simple and novel layer-by-layer (LBL) assembly in combination with covalent connection strategy for the synthesis of multifunctional carbon nanotubes (CNTs)-based magnetic-fluorescent nanohybrids as multimodal cellular imaging agents for detecting human embryonic kidney (HEK) 293T cells via magnetic resonance (MRI) and confocal fluorescence imaging. Superparamagnetic iron oxide nanoparticles (SPIO) and near-infrared fluorescent CdTe quantum dots (QDs) were covalently coupled on the surface of CNTs in sequence via LBL assembly. It was indicated that the SPIO layer acted not only as a contrast agent for MRI, but also as a spacer between CdTe QDs and CNTs for prohibiting fluorescence quenching of QDs on the surface of the CNTs. The multifunctional CNT-based magnetic-fluorescent nanohybrids showed an enhanced MRI signal as contrast agent for detecting 293T cells in comparison with the pure SPIO. This is due to the magnetic coupling between the orderly arrayed SPIO, the function of CNTs for lowering the transverse relaxation and the ability of CNTs for penetrating into cells. Moreover, the multifunctional CNT-based magnetic-fluorescent nanohybrids exhibited the higher intracellular labeling efficiency due to the ability of CNTs for penetrating into cells in comparison with pure SPIO-CdTe nanoparticles.
Co-reporter:Tao Liu, Dongsheng Li, Yu Zou, Deren Yang, Hailong Li, Yimin Wu, Minhua Jiang
Journal of Colloid and Interface Science 2010 Volume 350(Issue 1) pp:58-62
Publication Date(Web):1 October 2010
DOI:10.1016/j.jcis.2010.05.092
A universal self-assembly method is used to prepare a series of large-area silica-coated metal particle (metal@silica) films at the hexane/water interface. The decrease of hexane/water interfacial energy after the particle adsorption leads to the formation of films. Since external silica shells eliminate the coupling between neighboring metal core particles, the extinction peaks of closely packed metal@silica particle films are as narrow as those of monodispersed metal particles. In the detection of Raman scattering signals of R6G dyes by shell-isolated nanoparticle-enhanced Raman spectroscopy, the use of metal@silica particle films resulted in an average enhancement by a factor of 105.Graphical abstractOil–water interfacial self-assembly was used to prepare a series of films consisting of closely packed metal@silica particles.Research highlights► Oil-water interfacial self-assembly is used to prepare metal@silica films. ► Extinction properties of metal@silica films depend on the metal core particles. ► Silica layers control the coupling between neighboring metal core particles. ► Metal@silica particle films display high SERS effect.
Co-reporter:Peiliang Chen, Xiangyang Ma, Yuanyuan Zhang, Deren Yang
Journal of Luminescence 2010 Volume 130(Issue 6) pp:1073-1075
Publication Date(Web):June 2010
DOI:10.1016/j.jlumin.2010.01.027
Various metal–insulator–semiconductor (MIS) devices in the form of Au/SiOx(x<2)/Si, Au/AlOy(y<1.5)/Si, Au/SiOx/ZnO and Au/AlOy/ZnO have been fabricated. For each device, once a sufficiently high positive voltage is applied on the Au electrode, the same ultraviolet (UV) emission with a spectrum featuring several specific peaks is detected. Interestingly, such UV emissions related to the MIS devices originate from the external N2 microplasma. It is believed that at the high enough positive voltages the highly energetic electrons emitted out of the Au electrode activate the air to generate the N2 microplasma.
Co-reporter:Jin Xu, Yongzhi Wang, Deren Yang, H.J. Moeller
Journal of Alloys and Compounds 2010 Volume 502(Issue 2) pp:351-355
Publication Date(Web):23 July 2010
DOI:10.1016/j.jallcom.2010.04.164
The influence of nickel precipitation on the formation of denuded zone (DZ) in Czochralski silicon (Cz Si) was systematically investigated by means of Scanning Infrared Microscopy (SIRM) and optical microscopy (OM). It was found that, for conventional high-low-high annealing (CFA), the DZ can be obtained in all specimens contaminated by nickel impurity at different steps of the heat treatment, indicating that no nickel precipitates generated in the region just below the surface. Additionally, the width of the DZ is nearly the same in all specimens although the contamination sequence is different, indicating that the contamination temperature, that is, the corresponding equilibrium concentration of interstitial nickel in the silicon doesn’t influence significantly the thermodynamics and kinetics process of the formation of nickel precipitates. For Rapid thermal annealing (RTA)-low-high annealing, the tendency remained unchanged. On the basis of the experimental results, it is supposed that the formation of DZ is strongly influenced by the segregation gettering and intrinsic gettering of the nickel atoms, which were caused by the formation of nickel-silicon (Ni–Si) alloys close to the surface, oxygen precipitates and extended defects in the bulk, respectively.
Co-reporter:Peiliang Chen, Xiangyang Ma, Deren Yang
Optics Communications 2010 Volume 283(Issue 7) pp:1359-1362
Publication Date(Web):1 April 2010
DOI:10.1016/j.optcom.2009.11.063
We report fairly pure ultraviolet (UV) electroluminescence (EL) from a novel p-Si-based SiOx/ZnO/SiOx (x < 2) double-barrier device. When the device is forward biased with positive voltage applied on the gate electrode of Au film, UV light originated from the near-band-edge emission of ZnO is dominant in the EL spectra, while the defect-related visible emissions are undetectable. In the case of reverse bias, no EL is detected from the device. The mechanisms of EL and carrier transports have been explained in terms of energy band structures under forward and reverse biases.
Co-reporter:Peiliang Chen;Xiangyang Ma;Yuanyuan Zhang
Journal of Electronic Materials 2010 Volume 39( Issue 6) pp:652-655
Publication Date(Web):2010 June
DOI:10.1007/s11664-010-1173-9
An n-Mg0.2Zn0.8O/n-ZnO/SiOx (x < 2) heterostructure has been fabricated on n-Si by sputtering and electron-beam evaporation. The device showed nonrectifying behavior, and emitted strong white light under reverse bias with positive voltages applied to n-Si. The white-light electroluminescence (EL) is believed to result from electron–hole recombination at defect levels of ZnO. The EL mechanism has been tentatively explained in terms of the energy band structure of the device under forward and reverse bias.
Co-reporter:Yuheng Zeng;Xiangyang Ma;Jiahe Chen
Journal of Electronic Materials 2010 Volume 39( Issue 6) pp:648-651
Publication Date(Web):2010 June
DOI:10.1007/s11664-010-1197-1
Through an investigation of oxygen precipitation and extended defects in Czochralski silicon (CZ-Si) specimens subjected to different isothermal anneals, by scanning infrared microscopy and preferential etching combined with optical microscopy, the correlation between the sizes of oxygen precipitates and the generation of extended defects is revealed. It is found that extended defects are generated when oxygen precipitates grow. Afterward, the sizes of extended defects increase, while those of oxygen precipitates do not change significantly. For the onset of the generation of extended defects, we define the maximum size of oxygen precipitates as a critical size for the generation of extended defects. Moreover, it is revealed that this critical size decreases for higher annealing temperatures or more oxidizing ambients.
Co-reporter:Ning Du;Yanfang Xu;Hui Zhang;Chuanxin Zhai
Nanoscale Research Letters 2010 Volume 5( Issue 8) pp:
Publication Date(Web):2010 August
DOI:10.1007/s11671-010-9641-y
Hematite (α-Fe2O3) and magnetite (Fe3O4) nanowires with the diameter of about 100 nm and the length of tens of micrometers have been selectively synthesized by a microemulsion-based method in combination of the calcinations under different atmosphere. The effects of the precursors, annealing temperature, and atmosphere on the morphology and the structure of the products have been investigated. Moreover, Co3O4 nanowires have been fabricated to confirm the versatility of the method for metal oxide nanowires.
Co-reporter:Jiahe Chen, Xiangyang Ma, Deren Yang
Thin Solid Films 2010 Volume 518(Issue 9) pp:2334-2337
Publication Date(Web):26 February 2010
DOI:10.1016/j.tsf.2009.09.129
Czochralski silicon (Cz-Si) doped with germanium (Ge) has recently drawn the attentions on the next generation of Cz-Si materials used for ultra large-scale integrated circuits. Oxygen precipitate, which is the most important micro-defect in Ge-doped Cz-Si (GCz-Si), domains the majority properties of bulk silicon. In this presentation, the behaviors of oxygen precipitation in GCz-Si at high temperatures have been studied. It was found that, compared with conventional Cz-Si, the higher-density but smaller-sized oxygen precipitates were formed in GCz-Si at extremely high temperature, which could be ascribed to the enhanced nucleation of oxygen precipitates by the Ge-doping. Meanwhile, compound morphologies of oxygen precipitates consisted of plate-like and polyhedral shapes were found in GCz-Si, which can probably be ascribed to the different levels of vacancy coalesced by the so-called Ge-related complexes in GCz-Si.
Co-reporter:Zhizhong Yuan, Dongsheng Li, Zhihong Liu, Xiaoqiang Li, Minghua Wang, Peihong Cheng, Peiliang Chen, Deren Yang
Journal of Alloys and Compounds 2009 Volume 474(1–2) pp:246-249
Publication Date(Web):17 April 2009
DOI:10.1016/j.jallcom.2008.06.054
SnO2:Tb films on silicon wafers were prepared by DC reactive magnetron sputtering and ion-implantation. It was found that pure rutile polycrystalline SnO2 film with optical band gap of 4.0 eV was formed after high temperature annealing. Furthermore, defect-related light emission at 590 nm from the SnO2 substrate and the intra-4f transition from Tb3+ ions coexisted when the SnO2:Tb film was annealed at 1000 °C for 1 h after Tb3+ ion-implantation. The PL intensity of the D45→Fk7 (k = 6–3) transition of Tb3+ ion was greatly enhanced by the phosphorus diffusion treatment. It is proposed that the Tb3+ ions change from substitution sites to the enlarged interstitial sites in SnO2 host.
Co-reporter:Ning Du, Hui Zhang, Xiangyang Ma, DongSheng Li, Deren Yang
Materials Letters 2009 Volume 63(13–14) pp:1180-1182
Publication Date(Web):31 May 2009
DOI:10.1016/j.matlet.2009.02.037
A novel and simple chemical reaction method has been developed to synthesize the Tb(OH)3 nanorods with diameters of 20–30 nm and lengths of about 300 nm at 90 °C using cyclohexylamine as the alkaline source. The formation mechanism for the synthesis of the Tb(OH)3 nanostructures with different morphologies has been primarily discussed.
Co-reporter:Yuheng Zeng, Deren Yang, Zhenqiang Xi, Weiyan Wang, Duanlin Que
Materials Science in Semiconductor Processing 2009 Volume 12(4–5) pp:185-188
Publication Date(Web):August–October 2009
DOI:10.1016/j.mssp.2009.10.002
The iron precipitation in as-received Czochralski (CZ) silicon during low temperature from 300 to 700 °C was investigated. It was found that the iron precipitation rate was increased in turn from 300 to 700 °C. It was also found that the iron could form small precipitates even at low concentration. Moreover, iron precipitation was revealed as the diffusion-limited process, which could be described properly by Ham's law. This performance of iron precipitation in as-received CZ silicon was considered to be significantly influenced by the grown-in oxygen precipitates because of the fact that the grown-in oxygen precipitates could act as the heterogeneous nuclei for interstitial iron.
Co-reporter:Hui Zhang, Deren Yang, Xiangyang Ma
Materials Letters 2009 Volume 63(Issue 1) pp:1-4
Publication Date(Web):15 January 2009
DOI:10.1016/j.matlet.2008.08.001
Selenium (Se) nanotubes and nanowires have been controllably prepared by a solution-phase approach consisting of hydrothermal process and subsequent sonochemical process in different solvent including methanol, ethanol, acetone, dimethyl formamide, water, isopropanol and ethylene glycol. It is revealed that the formation of the Se nanotubes or nanowires is dependent on the breakage or not of the in-situ generated Se nanoparticles. The effects of the solvents on the morphology of Se nanostructures have been preliminarily discussed. Finally, Se nanotubes and nanowires have been characterized by X-ray powder diffraction (XRD), field emission scan electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and Raman spectroscopy.
Co-reporter:Tianfeng Cui, Hui Zhang, Ning Du, Bingdi Chen, Dongshen Li, Deren Yang
Materials Chemistry and Physics 2009 Volume 115(2–3) pp:562-566
Publication Date(Web):15 June 2009
DOI:10.1016/j.matchemphys.2009.01.006
A polyelectrolyte assisted chemical approach has been developed to synthesize well-dispersed EuF3 nanostructures with the controlled morphology and crystalline phase. It is indicated that the hexagonal doughnut-like EuF3 nanostructures with diameters of 200–300 nm have been spontaneously transformed into orthorhombic spindle-like EuF3 nanostructures with diameters of 100 nm and lengths of 250–400 nm with the extension of the reaction time. The negatively charged polyelectrolyte such as sodium poly(styrenesulfonate) (PSS) plays the critical role for the morphology and crystalline phase transformation of EuF3. Moreover, the different EuF3 nanostructures have been characterized by X-ray powder diffraction (XRD), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and photoluminescence (PL). Finally, the formation mechanism of the different EuF3 nanostructures has been primarily discussed.
Co-reporter:Yuheng Zeng, Deren Yang, Xiangyang Ma, Jiahe Chen, Duanlin Que
Materials Science and Engineering: B 2009 s 159–160() pp: 145-148
Publication Date(Web):
DOI:10.1016/j.mseb.2008.12.045
Co-reporter:Jiahe Chen, Deren Yang, Xiangyang Ma, Duanlin Que
Materials Science and Engineering: B 2009 s 159–160() pp: 235-238
Publication Date(Web):
DOI:10.1016/j.mseb.2008.10.061
Co-reporter:Bingdi Chen, Hui Zhang, Ning Du, Dongsheng Li, Xiangyang Ma, Deren Yang
Materials Research Bulletin 2009 44(4) pp: 889-892
Publication Date(Web):
DOI:10.1016/j.materresbull.2008.08.019
Co-reporter:Ning Du, Hui Zhang, Bindi Chen, Xiangyang Ma, Xiaohua Huang, Jiangping Tu, Deren Yang
Materials Research Bulletin 2009 44(1) pp: 211-215
Publication Date(Web):
DOI:10.1016/j.materresbull.2008.04.001
Co-reporter:Fangming Cui;Lei Wang;Zhenqiang Xi
Journal of Materials Science: Materials in Electronics 2009 Volume 20( Issue 7) pp:609-613
Publication Date(Web):2009 July
DOI:10.1007/s10854-008-9773-3
Non-crystalline copper indium disulphide (CuInS2) thin films had been deposited on ITO glass by chemical bath deposition (CBD) in acid conditions. Then polycrystalline CuInS2 films were obtained after sulfuration in sulfur atmosphere at 450 °C for 1.5 h. The films had been characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), Raman scattering measurements and energy dispersive X-ray analysis (EDX). The optical and electrical property of the thin films was also measured. The results showed that the pure, flatness, and well crystallized CuInS2 thin films with good electrical and optical property had been obtained, meaning that the chemical bath deposition in acid conditions is suitable for the deposition of CuInS2 thin films.
Co-reporter:Ning Du, Hui Zhang, Ping Wu, Jingxue Yu and Deren Yang
The Journal of Physical Chemistry C 2009 Volume 113(Issue 40) pp:17387-17391
Publication Date(Web):September 11, 2009
DOI:10.1021/jp906349c
A layer-by-layer (LBL) approach has been developed to synthesize uniform CNT−metal nanocomposites at room temperature. As the representative examples, CNT−Pt, CNT−Pd, and CNT−Sn nanocomposites have been fabricated to illustrate the basic idea presented here. The morphology, structure, and composition of the as-synthesized products have been characterized by transmission electron microscopy, high-resolution transmission electron microscopy, field emission scanning electron microscopy, X-ray powder diffraction, and X-ray photoelectron spectroscopy analyses. The effects of the charge density on the CNTs, the reduction rate, and the sonication process on the formation of uniform CNT−metal nanocomposites have been investigated.
Co-reporter:Ning Du, Hui Zhang, Bingdi Chen, Xiangyang Ma and Deren Yang
Chemical Communications 2008 (Issue 26) pp:3028-3030
Publication Date(Web):21 Apr 2008
DOI:10.1039/B800401C
SnO2Nanotubes were synthesized via a one-pot redox route at room temperature, in which the Kirkendall effect is definitely responsible for the formation of hollow structures.
Co-reporter:Hui Zhang, Chuanxin Zhai, Jianbo Wu, Xiangyang Ma and Deren Yang
Chemical Communications 2008 (Issue 43) pp:5648-5650
Publication Date(Web):14 Oct 2008
DOI:10.1039/B812752B
CoFe2O4 nanorings were synthesized by a simple solvothermal process, in which Ostwald ripening was definitely responsible for the formation of hollow structures, and their ferromagnetic behavior at room temperature was observed.
Co-reporter:Ning Du, Hui Zhang, Xiangyang Ma and Deren Yang
Chemical Communications 2008 (Issue 46) pp:6182-6184
Publication Date(Web):20 Oct 2008
DOI:10.1039/B812695J
CNT/Au/SnO2nanotubes have been synthesized through homogeneous coating of Au and SnO2nanocrystals on carbon nanotubes (CNTs) and applied in a room-temperature CO gas sensor.
Co-reporter:Yuheng Zeng, Deren Yang, Xiangyang Ma, Zhidan Zeng, Duanlin Que, Longfei Gong, Daxi Tian, Liben Li
Materials Science in Semiconductor Processing 2008 Volume 11(Issue 4) pp:131-136
Publication Date(Web):August 2008
DOI:10.1016/j.mssp.2009.05.004
Delineation of defects in the heavily doped n-type Czochralski silicon wafers by preferential etching is an issue not having been essentially solved. Herein, a chromium-free etchant based on HNO3–HF–H2O system, with an optimum volume ratio of VHNO3%:VHF%:VH2O%=20%:45%:35%VHNO3%:VHF%:VH2O%=20%:45%:35%, has been developed. It can reveal well the defects such as dislocation and oxygen precipitation-induced bulk microdefects (BMDs) in the heavily doped n-type silicon wafers with resistivities even lower than 1 mΩ cm. Moreover, this etchant is appropriate to delineate the defects on (1 1 1), (1 1 0) or (1 0 0) surface of silicon crystal. Furthermore, the density of oxygen precipitation-induced BMDs in the heavily doped n-type silicon wafers derived from the preferential etching using this newly developed etchant correlates well with that derived from scanning infrared microscopy (SIRM) within its detection limit.
Co-reporter:Peihong Cheng, Dongsheng Li, Zhizhong Yuan, Yu Zou, Deren Yang
Materials Chemistry and Physics 2008 Volume 111(2–3) pp:271-274
Publication Date(Web):15 October 2008
DOI:10.1016/j.matchemphys.2008.04.006
A two-dimensional self-assembly of uncapped Ag nanoparticles was prepared at the air–water interface. In the experiment, ethanol was added into the Ag-based colloid to reduce the surface charge density on the nanoparticles and the air–water interfacial energy, leading to the nanoparticles adsorption and assembling at the air–water interface. It was found that the array structure was controllable. The ordered nanoparticle array could be changed to a fractal structure by varying gradually the amount of the added ethanol. Moreover, it was demonstrated that the assembly was sensitive to the surface charge density on the particles, the Debye length in the colloid and the interfacial tension between nanoparticle/water (air).
Co-reporter:Weiyan Wang;Xuegong Yu
Journal of Materials Science: Materials in Electronics 2008 Volume 19( Issue 1 Supplement) pp:32-35
Publication Date(Web):2008 December
DOI:10.1007/s10854-007-9507-y
The effect of point defects on the recombination activity of copper (Cu) precipitates in p-type Czochralski (CZ) silicon has been investigated by means of microwave photoconductivity decay and electron beam induced current (EBIC). It was found that the value of the reciprocal of effective minority carrier lifetime and EBIC contrast of the samples with pre-annealing in Ar, without pre-annealing and with pre-annealing in O2, related to the recombination activity of Cu precipitates, decreased in turn. It was considered that the highest recombination activity of Cu precipitates in the sample with pre-annealing in Ar was mainly attributed to the relative higher minority carrier capture cross section of Cu precipitates, which was affected by the induced vacancies. While the weakest recombination activity of Cu precipitates in the sample with pre-annealing in O2 was ascribed to the relative lower density of Cu precipitates, which was influenced by the induced silicon interstitials.
Co-reporter:Zhizhong Yuan, Dongsheng Li, Minghua Wang, Daoren Gong, Ruixin Fan, Deren Yang
Vacuum 2008 Volume 82(Issue 11) pp:1337-1340
Publication Date(Web):19 June 2008
DOI:10.1016/j.vacuum.2007.12.015
The pn diodes were fabricated by implanting B ions into n-type Si substrate and followed by annealing at 950 °C for 20 min. Carrier concentrations of the pn diodes were measured by spreading resistance profile (SRP). The room-temperature photoluminescence (PL) and the microstructures of the defects resulted from the ion-implantation of the pn diodes were investigated. Electron-beam-induced current (EBIC) was measured to detect carrier recombinations at different depth in the pn diode. The enhanced PL line centered at about 1160 nm, which is related to band edge radiative recombination, was observed in the implanted sample. It was found that dislocation loops were formed in the p-type region which is above the pn junction. Moreover, there are intense carrier recombinations at the region of dislocation loops. The EBIC results proved that the enhanced luminescence originated from the region of dislocation loops, but not from the dislocation loops themselves. It is believed that the intense band edge luminescence is due to the quantum confinement of dislocation loops.
Co-reporter:Zhihong Liu, Hui Zhang, Lei Wang, Dongsheng Li, Deren Yang
Physica E: Low-dimensional Systems and Nanostructures 2008 Volume 40(Issue 3) pp:494-498
Publication Date(Web):January 2008
DOI:10.1016/j.physe.2007.07.006
A novel hydrofluoric acid (HF) free atmospheric pressure chemical vapor deposition (APCVD) method has been developed to synthesize macropores on silicon. Field emission scanning electron microscopy (FESEM), X-ray powder diffraction (XRD) and energy-dispersive X-ray (EDX) spectrum indicate that the composition of macropores with the diameters of several hundred nanometers is silica. Moreover, the mechanism of the formation of the macropores has been preliminarily discussed. The photoluminescence (PL) spectrum of the macropores shows a broad violet emission band with the peak position at 402 nm, which is related with the defects of silica.
Co-reporter:Ning Du, Hui Zhang, Juner Chen, Jingyu Sun, Bingdi Chen and Deren Yang
The Journal of Physical Chemistry B 2008 Volume 112(Issue 47) pp:14836-14842
Publication Date(Web):October 24, 2008
DOI:10.1021/jp8065376
A novel layer-by-layer approach has been developed to synthesize polycrystalline SnO2 hollow spheres with tunable shell thickness and size using SiO2 spheres as a template. The surface of the SiO2 spheres has been first modified by the polyelectrolyte, and subsequently, the compact SnO2 layer has deposited on the surface of the SiO2 spheres through a redox reaction because of the electrostatic attraction between the charged species. After HF etching treatment, the uniform SnO2 hollow spheres have been obtained. The approach presented herein has been extended to synthesize other metal oxide and sulfide hollow spheres such as In2O3 and ZnS. Moreover, the as-synthesized SnO2 hollow spheres have been applied in lithium-ion battery and show improved performance compared with SnO2 nanoparticles. The high surface area and stable hollow structure of the SnO2 hollow spheres may be responsible for the improved performance.
Co-reporter:Hui Zhang, Yiqiang Zhang, Jingxue Yu and Deren Yang
The Journal of Physical Chemistry C 2008 Volume 112(Issue 35) pp:13390-13394
Publication Date(Web):2017-2-22
DOI:10.1021/jp801507h
Single-crystalline, monodisperse copper sulfide nanocrystals with controlled sizes, shapes, and phases were successfully synthesized via a simple, low-cost, and environmentally friendly chemical reaction of CuCl2 and S in oleylamine at 100−180 °C. It was found that the molar ratios of [CuCl2]:[S] played the critical role for the control of the sizes, shapes, and phases of copper sulfide nanocrystals. The hexagonal CuS nanodisks, hexagonal CuS nanoribbons consisting of face-to-face stacked nanodisks, and monoclinic Cu1.75S nanoribbons consisting of face-to-face stacked nanodisks were obtained when the molar ratios of [CuCl2]:[S] were 1:1, 2:3, and 2:1, respectively. It was believed that the van der Waals force and dipole−dipole interaction were responsible for the self-assembly of copper sulfide nanodisks. Finally, the copper sulfide nanocrystals were characterized by transmission electron microscopy, high-resolution transmission electron micrscopy, X-ray diffraction, and Fourier transform infrared, and its growth mechanism was primarily discussed.
Co-reporter:N. Du;H. Zhang;X. Y. Ma;Z. H. Liu;B. D. Chen;J. B. Wu;D. R. Yang
Advanced Materials 2007 Volume 19(Issue 12) pp:1641-1645
Publication Date(Web):23 MAY 2007
DOI:10.1002/adma.200602128
Porous and polycrystalline In2O3nanotubes are prepared by layer-by-layer assembly on CNT templates and subsequent calcination (see figure). The as-prepared In2O3 nanotubes exhibit superior sensitivity to NH3 at room temperature, as well as a good reproducibility and short response/recovery time. This novel approach presented herein can be extended to synthesize other metal oxide nanotubes such as NiO, SnO2, Fe2O3, and CuO.
Co-reporter:Ning Du, Hui Zhang, Hongzhi Sun, Deren Yang
Materials Letters 2007 Volume 61(Issue 1) pp:235-238
Publication Date(Web):January 2007
DOI:10.1016/j.matlet.2006.04.039
Long silver sulfide nanowires have been prepared via the thioglycolic acid (TGA)-assisted sonochemical method. The transmission electron microscope (TEM) and field emission scanning electron microscope (FESEM) images reveal that the nanowires have uniform width and length. The selected area electron diffraction (SAED) pattern indicates that the Ag2S nanowires are amorphous. Furthermore, the mechanism for the TGA-assisted sonochemical synthesis of Ag2S nanowires has been preliminarily presented.
Co-reporter:Zhizhong Yuan, Dongsheng Li, Daoren Gong, Minghua Wang, Ruixin Fan, Deren Yang
Materials Science in Semiconductor Processing 2007 Volume 10(4–5) pp:173-178
Publication Date(Web):August–October 2007
DOI:10.1016/j.mssp.2007.11.002
Silicon pn diodes were fabricated by ion implantation of B and P ions with different doses and subsequent annealing processes. Room temperature photoluminescence (PL) were investigated and the factors affecting the PL intensity were analyzed. Results show that both kinds of pn diodes have PL peak centered at about 1140 nm. Dislocation loops resulted from ion implantation and annealing process may enhance the light emission of silicon pn diode due to its band quantum confinement effect to carriers. The luminescence intensity depends on the carrier concentrations in the implantation region. It should be controlled at the range of 1–6×1016 cm−3. Moreover, the PL intensities of pn diodes with furnace annealing (FA) are higher than those with rapid thermal annealing, and the annealing temperature range for FA is 900–1100 °C.
Co-reporter:Weiyan Wang, Deren Yang, Xiangyang Ma, Yuheng Zeng, Duanlin Que
Materials Science in Semiconductor Processing 2007 Volume 10(4–5) pp:222-226
Publication Date(Web):August–October 2007
DOI:10.1016/j.mssp.2008.01.002
The recombination activities of nickel (Ni) in p-type nitrogen-doped Czochralski (NCZ) silicon (Si) subjected to the rapid thermal processing (RTP) under different temperatures, atmospheres or cooling rates were investigated by means of microwave photoconductivity decay and scanning infrared microscopy. It was found that the value of the reciprocal of effective minority carrier lifetime (1/τeff) of NCZ Si, related to the recombination activity of Ni, increased with the annealing temperature or cooling rate, while, it was almost insensitive of the annealing atmosphere. Moreover, the 1/τeff of the Ni-contaminated NCZ Si was lower than that of the Ni-contaminated conventional Czochralski (CZ) Si annealed under the same condition. It is considered that the nitrogen-related defects or large grown-in oxygen precipitates might be the reason of relative lower recombination activity of Ni in NCZ Si.
Co-reporter:Hongliang Zhu;Luming Zhu;Hong Yang;Dalai Jin
Journal of Materials Science 2007 Volume 42( Issue 22) pp:9205-9209
Publication Date(Web):2007 November
DOI:10.1007/s10853-007-1887-0
This paper proposes a facile two-step hydrothermal route for the synthesis of maghemite (γ-Fe2O3) nanocrystals. The synthesis route included two steps: (i) hydrothermal synthesis of Fe3O4 nanocrystals, and (ii) hydrothermal oxidation of the Fe3O4 nanocrystals to their γ-Fe2O3 counterpart. Phase transition from γ-Fe2O3 to hematite was studied by in situ XRD; the γ-Fe2O3 nanocrystals exhibited enhanced phase transition temperature (>600 °C). The magnetization curves revealed that the γ-Fe2O3 nanocrystals showed ferromagnetic behavior with high saturation magnetization of 68 emu/g at room temperature.
Co-reporter:Xingbo Liang, Lei Wang, Xiaoqiang Li, Deren Yang
Thin Solid Films 2007 Volume 515(Issue 17) pp:6707-6712
Publication Date(Web):13 June 2007
DOI:10.1016/j.tsf.2007.01.044
Rapid thermal annealing (RTA) has been performed on the carbon films prepared by radio frequency plasma-enhanced chemical vapor deposition on Si substrate. The RTA at 800 °C for 60 s leads to the formation of many diamond nanocrystallites agglomerating on the film surface. Higher temperature RTA at 1100 °C for 60 s induces the high-density amorphous SiOx (x = 1.2) nanowires on the film surface without diamond nanocrystallites. At both the RTA temperatures, a well-oriented SiC interlayer is also formed simultaneously. The sp3 sites in the carbon film and the oxygen during the RTA treatment as well as the RTA temperature are considered to play important roles in determining the final reaction products.
Co-reporter:Zhihong Liu, Jia Sha, Qing Yang, Zixue Su, Hui Zhang, Deren Yang
Physica E: Low-dimensional Systems and Nanostructures 2007 Volume 38(1–2) pp:27-30
Publication Date(Web):April 2007
DOI:10.1016/j.physe.2006.12.028
In this paper we present a flower-like silicon nanostructure grown by combining the oxidation-assisted growth (OAG) mechanism and the vapor–liquid–solid (VLS) growth mechanism. It is found that the flower-like silicon nanostructures are nucleated initially via the VLS mechanism and then grown on silicon wafer via the OAG mechanism. Furthermore, light emission was observed, which is considered to be the enhanced photothermal effect.
Co-reporter:Hui Zhang, Ning Du, Jianbo Wu, Xiangyang Ma, Deren Yang, Xiaobin Zhang, Zhiqing Yang
Materials Science and Engineering: B 2007 Volume 141(1–2) pp:76-81
Publication Date(Web):25 June 2007
DOI:10.1016/j.mseb.2007.06.001
The straight and dendrite-like growths of ZnO have been completely and simply controlled by the status of ZnO seed instead of surfactant, template, oriented attachment, and ZnO buffer layer on the substrate in the chemical reaction synthesis of ZnO nanostructures. The monodisperse ZnO seeds, which are prepared by in situ quickly injecting the cool mixed zinc acetate and potassium hydrate ethanol solution into the hot matrix aqueous solution of zinc nitrate hydrate and diethylenetriamine at 95 °C, improve the straight growth and lots of uniform, straight, and single-crystalline ZnO nanorods with about 20–30 nm in diameter and 300 nm in length are achieved. While, the aggregated ZnO seeds, which are prepared by dropwise adding potassium hydrate ethanol solution into zinc acetate ethanol solution at 60 °C for 3 h, result in the dendrite-like growth and the bur-like ZnO nanostructures consisting of hundreds of nanorods with about 30–50 nm in diameter and several micrometers in length are formed. Furthermore, the approach presented here provides a simple, low-cost, environmental-friendly and high efficiency route to synthesize the high quality ZnO nanorods and bur-like ZnO nanostructures.
Co-reporter:Can Cui, Deren Yang, Xiangyang Ma, Ming Li, Duanlin Que
Materials Science in Semiconductor Processing 2006 Volume 9(1–3) pp:110-113
Publication Date(Web):February–June 2006
DOI:10.1016/j.mssp.2006.01.034
In this paper, the effect of light Germanium (Ge-) doping on thermal donors (TDs) in Czochralski silicon (CZ-Si) has been investigated by four-point probe and low-temperatures Fourier transform infrared (FTIR) spectrometer. After 650 °C, 30 min annealing to eliminate the grown-in TDs, conventional CZ-Si and germanium-doped CZ-Si (GCZ-Si) samples were further subjected to isothermal annealing at about 450 °C to generate TDs. It was found that Ge-doping suppressed the formation of TDs. Moreover, the low temperature FTIR absorption spectra of the TDs in GCZ-Si were found to agree quite well with that of TDs in CZ-Si, which was not the case for the heavily Ge-doped silicon. Therefore, it is considered that the light Ge-doping suppresses the formation of TDs but does not affect the microscopic structure of TDs.
Co-reporter:Weiyan Wang, Zhenqiang Xi, Deren Yang, Duanlin Que
Materials Science in Semiconductor Processing 2006 Volume 9(1–3) pp:296-299
Publication Date(Web):February–June 2006
DOI:10.1016/j.mssp.2006.01.057
The recombination activity of nickel in p- and n-type Czochralski silicon after rapid thermal process (RTP) in N2, O2 or Ar ambient has been investigated by the microwave photoconductivity decay technique. The effective lifetime of silicon decreases monotonically with increasing nickel in-diffusion temperature, and exhibits a step-like behavior at nickel in-diffusion temperature of 900 °C, which indicates that most of nickel atoms precipitate in the bulk no matter what kind of conducting type if the annealing temperature is above 900 °C under RTP. It is also found that the ambient during RTP almost has no effect on the recombination activity of nickel in silicon, which suggests point defects almost have no influence on the nickel precipitation.
Co-reporter:Xingbo Liang, Lei Wang, Deren Yang
Materials Letters 2006 Volume 60(Issue 6) pp:730-733
Publication Date(Web):March 2006
DOI:10.1016/j.matlet.2005.10.001
Nanocrystalline diamond films (NDFs) have been deposited using radio-frequency plasma enhanced chemical vapor deposition (r.f.-PECVD) at temperature as low as 500 °C. The CO/H2 ratio has been shown to exert a profound effect on the structure configuration of the NDFs. The nano-scale structures of the films have been shown to evolve from columnar structure to grainy structure with the increase of the CO/H2 ratio from 12:1 to 20:1. Such evolution is suggested to be the result of the enhanced secondary nucleation process. It gives an insight of the nucleation and growth process of NDFs and provides useful information on the optimal control of NDFs deposition.
Co-reporter:Hui Zhang, Deren Yang, Hongzhi Sun, Xiangyang Ma, Duanlin Que
Materials Letters 2006 Volume 60(Issue 16) pp:2004-2008
Publication Date(Web):July 2006
DOI:10.1016/j.matlet.2005.12.068
Sulfide coaxial cable nanostructures and nanotubes, such as CuS nanotubes, CdS/CuS coaxial cable nanostructures, Ag2S nanotubes, and CdS/Ag2S coaxial cable nanostructures have been prepared by a versatile and sacrificial approach based on substitution reaction and subsequent H2SO4 treatment. The morphology and structure of the nanomaterials have been characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and selected area electron diffraction (SAED) pattern. Moreover, the formation mechanism for the sulfide coaxial cable nanostructures and nanotubes has been phenomenologically discussed.
Co-reporter:Huixiang Tang, Mi Yan, Hui Zhang, Shenzhong Li, Xingfa Ma, Mang Wang, Deren Yang
Sensors and Actuators B: Chemical 2006 Volume 114(Issue 2) pp:910-915
Publication Date(Web):26 April 2006
DOI:10.1016/j.snb.2005.08.010
Gas sensors based on the Fe2O3–ZnO nanocomposites with different compositions of Fe:Zn was prepared by a sol–gel and spin-coating method. Morphology of the Fe2O3–ZnO nanocomposites was characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD, D/max-rA) and energy dispersive X-ray analysis (EDX). The results of electrical and sensing measurement indicated that the sensor with Fe:Zn = 2% exhibited fairly excellent sensitivity and selectivity to NH3 at room temperature. The response and recovery time of the sensor were both less than 20 s. Finally, the mechanism for the improvement in the gas sensing properties was discussed.
Co-reporter:Guoyin Huang, Zhenqiang Xi, Deren Yang
Vacuum 2006 Volume 80(Issue 5) pp:415-420
Publication Date(Web):26 January 2006
DOI:10.1016/j.vacuum.2005.07.006
In the present work, the effect of low temperature short-time rapid thermal processing (RTP) pretreatment on the average grain size and the crystallinity of the polycrystalline silicon thin films, fabricated by subsequent solid phase crystallization (SPC) of amorphous silicon (a-Si) thin films grown by radio-frequency plasma-enhanced chemical vapor deposition (RF-PECVD) at high temperature has been studied. The average grain size and the crystallinity results were estimated using X-ray diffraction (XRD) and Raman spectroscopy, respectively. It was found that RTP at 800 °C for 60 s resulted in slightly larger average grain size and higher crystallinity than those without the RTP pretreatment after SPC at 800 °C for 5, 10 and 22 h. The results suggest that the low-temperature short-time RTP pretreatment can promote the crystallization process of the as-deposited a-Si thin films during the following SPC and then improve their crystallinity. Finally, the mechanism is also discussed in detail in the paper.
Co-reporter:Deren Yang, Ming Li, Can Cui, Xiangyang Ma, Duanlin Que
Materials Science and Engineering: B 2006 Volume 134(2–3) pp:193-201
Publication Date(Web):15 October 2006
DOI:10.1016/j.mseb.2006.06.056
Nitrogen is one of the most important elements in Czochralski (CZ) silicon used in ultra-large scale integrity circuits (ULSI). In last decades, nitrogen-doped Czochralski (NCZ) silicon, which has been widely applied in microelectronic industry, has attracted much attention. In this presentation, the behavior of NCZ silicon treated in rapid thermal process (RTP) has been reviewed. The influence of RTP on oxygen precipitation, bulk microdefects, denuded zone and nitrogen and oxygen complexes in NCZ silicon has been investigated. The interaction of nitrogen with oxygen and vacancies in CZ silicon during RTP is also discussed.
Co-reporter:Huixiang Tang, Mi Yan, Xingfa Ma, Hui Zhang, Mang Wang, Deren Yang
Sensors and Actuators B: Chemical 2006 Volume 113(Issue 1) pp:324-328
Publication Date(Web):17 January 2006
DOI:10.1016/j.snb.2005.03.024
Gas sensors based on polyvinylpyrrolidone (PVP)-modified ZnO nanoparticles with different molar ratios of Zn2+: PVP were prepared by a sol–gel method. Morphology of the sensors was characterized by field emission-scanning electron microscopy (FE-SEM), which indicated that the sensor with a molar ratio of Zn2+: PVP = 5:5 showed uniform morphology. Moreover, the sensor exhibited fairly excellent sensitivity and selectivity to trimethylamine (TMA). The response and recovery time of the sensor were 10 and 150 s, respectively. Finally, the mechanism for the improvement in the gas sensing properties was discussed.
Co-reporter:Yue Zhao, Deren Yang, Dongsheng Li, Minghua Jiang
Applied Surface Science 2005 Volume 252(Issue 4) pp:1065-1069
Publication Date(Web):15 November 2005
DOI:10.1016/j.apsusc.2005.01.176
Abstract
The photoluminescence (PL) of the annealed and amorphous silicon passivated porous silicon with blue emission has been investigated. The N-type and P-type porous silicon fabricated by electrochemical etching was annealed in the temperature range of 700–900 °C, and was coated with amorphous silicon formed in a plasma-enhanced chemical vapor deposition (PECVD) process. After annealing, the variation of PL intensity of N-type porous silicon was different from that of P-type porous silicon, depending on their structure. It was also found that during annealing at 900 °C, the coated amorphous silicon crystallized into polycrystalline silicon, which passivated the irradiative centers on the surface of porous silicon so as to increase the intensity of the blue emission.
Co-reporter:Huixiang Tang, Mi Yan, Hui Zhang, Mingzhe Xia, Deren Yang
Materials Letters 2005 Volume 59(8–9) pp:1024-1027
Publication Date(Web):April 2005
DOI:10.1016/j.matlet.2004.11.049
The water-soluble CdS nanoparticles were obtained by hydrogen bond between the cadmium-thiolate complex on the surface of CdS nanoparticles and ethylene diamine (anhydrous). The modified CdS nanoparticles enhanced its solubility in H2O and alcohol. The ethylene diamine-capped CdS nanoparticles were characterized by Fourier Transform Infrared Spectroscopy (FTIR), photoluminescence (PL) and Ultraviolet–Visible absorption spectrum (UV–Vis spectrum). The absorption peak at 262 nm was observed, which belonged to ethylene diamine-modificated Cd-thiolate complex at the surface of as-grown CdS nanoparticles. The results of the PL spectra indicated that the modification of CdS nanoparticles reduced effectively the local surface-trap states. Based on the above results, a possible mechanism for the formation of the water-soluble CdS nanoparticles was discussed.
Co-reporter:Hui Zhang, Deren Yang, Xiangyang Ma, Yujie Ji, ShenZhong Li, Duanlin Que
Materials Chemistry and Physics 2005 Volume 93(Issue 1) pp:65-69
Publication Date(Web):15 September 2005
DOI:10.1016/j.matchemphys.2005.02.011
The CdS nanoparticles have been assembled into CdS nanorods and arrayed nanorod bundles by a thioglycolic acid (TGA) assisted hydrothermal processes using sodium sulfide (Na2S) and thiourea ((NH2)2CS) as the sulfur source, respectively. High-resolution transmission electron microscopy (HRTEM) shows that the CdS nanorods are single crystalline and the arrayed nanorod bundles are polycrystalline in nature. It is believed that the CdS nanorods were formed through the cluster-to-cluster oriented attachment mechanism, while the CdS nanorods bundles were formed through the particle-to-particle oriented attachment mechanism. In addition, the optical properties of CdS nanostructures were characterized by photoluminescence spectra (PL) and Raman spectroscopy.
Co-reporter:Jun Wang, Jian Sha, Qing Yang, Youwen Wang, Deren Yang
Materials Research Bulletin 2005 Volume 40(Issue 9) pp:1551-1557
Publication Date(Web):1 September 2005
DOI:10.1016/j.materresbull.2005.04.016
A sol–gel process followed by annealing was employed to fabricate single crystal aluminium borate (Al4B2O9 and Al18B4O33) nanowires. The diameter of Al4B2O9 nanowires synthesized at 750 °C annealing is ranging from 7 to 17 nm, and that of Al18B4O33 nanowires synthesized at 1050 °C annealing is about 38 nm. Instead of the well-known vapor–liquid–solid (VLS) mechanism, self-catalytic mechanism was used to explain the growth of the nanowires.
Co-reporter:Jun Wang, Jian Sha, Qing Yang, Xiangyang Ma, Hui Zhang, Jun Yu, Deren Yang
Materials Letters 2005 Volume 59(Issue 21) pp:2710-2714
Publication Date(Web):September 2005
DOI:10.1016/j.matlet.2005.04.026
Large-scale aligned ZnO nanowires are grown uniformly on silicon substrates covered with polycrystalline ZnO films by carbothermal route, without employing any metal catalysts and vacuum system. The products collected from the different temperature zones were characterized using X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, and photoluminescence spectroscopy. It was found the (001) oriented single crystal ZnO nanowires with different diameters could be fabricated. It is suggested that the ZnO films with smaller grain sizes may offer the nucleation centers for the formation of ZnO nanowires.
Co-reporter:Qing Yang, Jian Sha, Xiangyang Ma, Deren Yang
Materials Letters 2005 Volume 59(14–15) pp:1967-1970
Publication Date(Web):June 2005
DOI:10.1016/j.matlet.2005.02.037
A sol-gel process and subsequent calcination was employed to fabricate NiO nanowires. It is identified that the obtained NiO nanowires are hexagonal and single crystalline in nature. It is also found that some of the nanowires branch. The formation mechanism of NiO nanowires has been discussed. It is considered that the sol-gel process in which the citric acid acted as the chelate played a critical role in the formation of NiO nanowires, and the vapor–solid (VS) mechanism was responsible for the formation of the nanowires.
Co-reporter:Yue Zhao, Deren Yang, Dongsheng Li, Minghua Jiang
Materials Science and Engineering: B 2005 Volume 116(Issue 1) pp:95-98
Publication Date(Web):15 January 2005
DOI:10.1016/j.mseb.2004.08.014
The blue emission resulting from the as-prepared and oxidized porous silicon (PS) was reported in this paper. After the oxidation in plasma enhanced chemical vapor deposition (PECVD) process, the blue emission intensity in photoluminescence (PL) spectra increased because it is believed that the blue emission came from defects in silicon dioxides. Under UV-light illumination, the stability of the blue emission of the N-type oxidized PS was improved due to oxidation.
Co-reporter:Qing Yang, Jian Sha, Lei Wang, Yu Zou, Junjie Niu, Can Cui, Deren Yang
Physica E: Low-dimensional Systems and Nanostructures 2005 Volume 27(Issue 3) pp:319-324
Publication Date(Web):April 2005
DOI:10.1016/j.physe.2004.12.015
Crystalline boron oxide nanowires have been synthesized on silicon substrates by chemical vapor deposition (CVD) process without the use of catalysts or templates. It is pointed out that the boron oxide nanowires are cubic and single crystalline, and the diameter of the nanowires is in the range of 20–80nm. Some of the nanowires branched, and the diameters of the branches and stems of the branched boron oxide nanowires are in the range of 20–80 and 100–200nm, respectively. The crystallinity, morphology, and structure features of the as-prepared boron oxide nanowires were investigated by field emission scanning electron microscopy, X-ray diffraction, transmission electron microscopy, and selected area electron diffraction. Furthermore, Raman spectrum and Fourier transform infrared spectroscopy of the nanowires were also investigated.
Co-reporter:Deren Yang, Daxi Tian, Jin Xu, Xiangyang Ma, Duanlin Que, A. Misiuk, B. Surma
Journal of Alloys and Compounds 2004 Volume 382(1–2) pp:275-277
Publication Date(Web):17 November 2004
DOI:10.1016/j.jallcom.2004.05.044
Microstructure of the oxygen precipitates and of the annealing induced defects in nitrogen-doped Czochralski (NCZ) and conventional (CZ) silicon subjected to two-steps treatment under high pressure (HP) up to 1.1 GPa has been investigated by means of photoluminescence (PL) spectroscopy. It has been found that the creation of oxygen precipitates and defects in the CZ-Si and NCZ-Si subjected to the high pressure heat treatments (HT–HP) at up to 1130 °C is dependent both on annealing temperature (HT) and HP. Nitrogen doping affects the microstructure of NCZ-Si so that PL spectra of HT–HP treated NCZ-Si are different from these of CZ-Si.
Co-reporter:Junjie Niu, Jian Sha, Deren Yang
Physica E: Low-dimensional Systems and Nanostructures 2004 Volume 24(3–4) pp:178-182
Publication Date(Web):September 2004
DOI:10.1016/j.physe.2004.03.022
Silicon nano-wires (SiNWs) with diameter of and length of tens of micrometers on silicon wafers were synthesized by a novel thermal evaporation of zinc sulfide. After thermal evaporation at 1080°C for , crystalline SiNWs were produced. It was found that the tip of SiNWs contained sulfur, while the other places of SiNWs did not. It is considered that the decomposition of SiS resulted in the formation of SiNWs. On the basis of the facts, a sulfide-assisted growth model of SiNWs was suggested.
Co-reporter:Junjie Niu, Jian Sha, Zhihong Liu, Zixue Su, Jun Yu, Deren Yang
Physica E: Low-dimensional Systems and Nanostructures 2004 Volume 24(3–4) pp:268-271
Publication Date(Web):September 2004
DOI:10.1016/j.physe.2004.04.040
Thin silicon nano-wires (SiNWs) with a diameter of ∼10–20 nm were fabricated by a simple thermal evaporation of silicon wafer at 1523 K. The gold produced by an electrochemical method was covered on the wafer surface as catalyst. It was found that the SiNWs are amorphous and its Raman peak shifted down maybe due to the effect of laser heating and quantum confinement. Finally, a temperature gradient growth model is suggested to explain the growth direction of SiNWs.
Co-reporter:Junjie Niu, Jian Sha, Deren Yang
Physica E: Low-dimensional Systems and Nanostructures 2004 Volume 24(3–4) pp:278-281
Publication Date(Web):September 2004
DOI:10.1016/j.physe.2004.05.002
Silicon nanowires (SiNWs) with a diameter of ∼20 nm were synthesized by the thermal evaporation of sulfur powders on silicon wafers. The source of the SiNWs came from the silicon substrates. It is considered that the generated SiS compound assisted the formation of SiNWs. Finally, the Raman shift of SiNWs was discussed.
Co-reporter:Junjie Niu, Jian Sha, Yujie Ji, Deren Yang
Physica E: Low-dimensional Systems and Nanostructures 2004 Volume 24(3–4) pp:328-332
Publication Date(Web):September 2004
DOI:10.1016/j.physe.2004.06.041
Tiny silicon nano-wires (SiNWs) were synthesized on silicon wafers by the chemical vapor deposition (CVD) technique. The morphology and structure of tiny SiNWs were analyzed by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM) and X-ray diffraction (XRD), respectively. The results indicate that the tiny SiNWs were part-crystalline structure and were about 3 nm in minimal diameter. Based on the line shift of Raman spectra, the structure transform of the tiny SiNWs was discussed. The defect-inducing growth mechanism will probably provide a new method for the minimum of the one-dimensional nano-materials.
Co-reporter:Haiyan Zhu, Xuegong Yu, Xiaodong Zhu, Yichao Wu, Jian He, Jan Vanhellemont, Deren Yang
Superlattices and Microstructures (November 2016) Volume 99() pp:192-196
Publication Date(Web):November 2016
DOI:10.1016/j.spmi.2016.03.006
Co-reporter:Kun Huang, Yucong Yan, Xuegong Yu, Hui Zhang, Deren Yang
Nano Energy (February 2017) Volume 32() pp:
Publication Date(Web):February 2017
DOI:10.1016/j.nanoen.2016.12.042
•Pt NPs coupled with Gr double the efficiency of Gr-Si solar cells.•Enhancement of Pt NPs comes from their plasmonic effect and physical doping abilityon Gr.•The photo-induced doping of Pt NPs on Gr is firstly reported on Gr-Si solar cells.•The coupling of Pt NPs is air-stable and antireflection-coating-compatible.Graphene-silicon (Gr-Si) solar cells have been intensively investigated in recent years, which exhibits a potential application of two-dimensional materials in photovoltaics. However, the pristine Gr with low carrier concentration and therefore low work function is not suitable for the fabrication of high performance solar cells. Chemical doping is an effective way to improve the carrier concentration of Gr, but it is not stable and the efficiency of solar cell suffers heavy degradation. Here, we have developed a novel Gr-Si device structure with the coupling of two-dimensional Gr with zero-dimensional Pt nanoparticles on the top of bulk Si. The utilization of Pt nanoparticle can effectively enhance the sunlight absorption of solar cells by the plasmonic effect. Meanwhile, the carrier concentration and work function of Gr get greatly improved by physical doping of high-work-function Pt nanoparticle, and therefore the potential barrier at Gr-Si interface is significantly increased. More interestingly, the photo-induced doping of Pt nanoparticles for the Gr based on charge transfer has been observed for the devices under sunlight illumination. As a result, an efficiency of 7% has been achieved for our pristine solar cells, which is much higher than that of the control ones, ~4%. These devices with integration of zero-two-three dimensional materials have excellent air-stability, much more advantageous than the chemically doped ones. The efficiency of solar cell can further reach 10% by the application of spin-coated TiO2 anti-reflective film. These results point out a new route to the fabrication of high efficiency Gr-Si solar cells for photovoltaic application.
Co-reporter:Deren Yang, Jiahe Chen, Xiangyang Ma, Duanlin Que
Journal of Crystal Growth (15 January 2009) Volume 311(Issue 3) pp:837-841
Publication Date(Web):15 January 2009
DOI:10.1016/j.jcrysgro.2008.09.194
Impurities in Czochralski silicon (Cz-Si) used for ultra large-scaled-integrated (ULSI) circuits have been believed to deteriorate the performance of devices. In this paper, a review of the recent processes from our investigation on internal gettering in Cz-Si wafers which were doped with nitrogen, germanium and/or high content of carbon is presented. It has been suggested that those impurities enhance oxygen precipitation, and create both denser bulk microdefects and enough denuded zone with the desirable width, which is benefit of the internal gettering of metal contamination. Based on the experimental facts, a potential mechanism of impurity doping on the internal gettering structure is interpreted and, a new concept of ‘impurity engineering’ for Cz-Si used for ULSI is proposed.
Co-reporter:Yuheng Zeng, Jiahe Chen, Miangyang Ma, Weiyan Wang, Deren Yang
Journal of Crystal Growth (15 February 2010) Volume 312(Issue 5) pp:
Publication Date(Web):15 February 2010
DOI:10.1016/j.jcrysgro.2010.01.012
Co-reporter:Xiaodong Zhu, Xuegong Yu, Deren Yang
Journal of Crystal Growth (1 September 2014) Volume 401() pp:141-145
Publication Date(Web):1 September 2014
DOI:10.1016/j.jcrysgro.2014.03.017
•We review the effects of Ge doping on B-related defects in crystalline silicon.•Ge doping increases the diffusion barriers of Fei and O2i.•Ge–B complexes increase the formation energies of FeB pairs and B–O defects.•The saturated concentration of B–O defects can be reduced due to Ge doping.•Ge doping improves the efficiency of solar cells and the power output of corresponding modules.Recently it has been recognized that germanium (Ge) doping can be used for microelectronics and photovoltaic devices. This article reviews the recent results about the effects of Ge doping on boron-related defects in crystalline silicon. Behavior of Ge interacting with the acceptor dopants is also discussed therein. In addition, the article provides a comprehensive review on the effect of Ge doping to the formation of iron–boron pairs and boron–oxygen defects that is responsible for the light induced degradation (LID) of the carrier lifetime. The improvement silicon-based solar cells application from Ge doping is discussed as well, including the increment of cell efficiency and the power output of corresponding modules under sunlight illumination.
Co-reporter:Yu Zou, Dongsheng Li, Deren Yang
Journal of Crystal Growth (1 November 2010) Volume 312(Issue 22) pp:3406-3409
Publication Date(Web):1 November 2010
DOI:10.1016/j.jcrysgro.2010.08.030
We report a simple method of fast synthesis of CdSeS nanorods with chemical composition gradients. The CdSeS nanorods were prepared by single-step addition of Se and S source mixture into Cd precursor solution at elevated temperatures. The size of the nanorods can be tuned by changing the S/Se feed molar ratio. As a result of the reactivity difference between Se and S precursors, the nanorods have a core/shell structure with chemical composition gradients, leading to enhancements of their photoluminescence quantum yield and photostability, which make them attractive for use in optoelectronic devices and bio-labeling.
Co-reporter:Peng Wang, Xuegong Yu, Zhonglan Li, Deren Yang
Journal of Crystal Growth (1 March 2011) Volume 318(Issue 1) pp:230-233
Publication Date(Web):1 March 2011
DOI:10.1016/j.jcrysgro.2010.11.081
The impact of germanium doping on the fracture strength of multicrystalline silicon (mc-Si) has been investigated by three-point bending testing. It is found that after the damaged layer removal by chemical etching, germanium doped multicrystalline silicon (Gmc-Si) wafers show significantly improved fracture strength compared to conventional mc-Si ones. Moreover, the improvement of the percentage of the fracture strength increases with decrease in thickness of the etched wafers. This suggests that the fracture toughness of mc-Si wafers is enhanced by germanium doping. The results are of interest for solar cells production yields improvement in the photovoltaic industry.
Co-reporter:Xuegong Yu, Deren Yang, Keigo Hoshikawa
Journal of Crystal Growth (1 March 2011) Volume 318(Issue 1) pp:178-182
Publication Date(Web):1 March 2011
DOI:10.1016/j.jcrysgro.2010.10.087
The behaviors of nitrogen during Czochralski (CZ) silicon crystal growth have been investigated in this paper. It is found that the nitrogen impurities in silicon mainly exist as nitrogen pair and nitrogen–oxygen complex. The nitrogen concentration can be exactly determined by Fourier transformed infrared spectroscopy (FTIR) after eliminating the thermal donors. Above a critical concentration of 4×1015/cm3, the nitrogen impurities easily form Si3N4 particles, causing the dislocations, grain boundary and cellular structure in the crystal. Meanwhile, with a nitrogen-doped seed, the dislocations due to thermal shocking during the dipping process can be effectively suppressed at the seed/crystal interface, which will allow growing a crystal without a Dash neck. These results are of interest for the CZ silicon crystal growth in semiconductor industry.
Co-reporter:Yuheng Zeng, Jiahe Chen, Miangyang Ma, Weiyan Wang, Deren Yang
Journal of Crystal Growth (1 June 2009) Volume 311(Issue 12) pp:3273-3277
Publication Date(Web):1 June 2009
DOI:10.1016/j.jcrysgro.2009.03.048
Oxygen precipitation in conventional and nitrogen co-doped heavily phosphorus (P)-doped Czochralski silicon (CZ-Si) crystal subjected to various high-temperature annealing in the range of 1000–1150 °C was comparatively investigated. It was revealed that oxygen precipitates hardly generated in conventional heavily P-doped CZ-Si; while they remarkably generated in the nitrogen co-doped one. Moreover, nitrogen doping could enhance oxygen precipitation during the prolonged annealing with a rapid thermal process (RTP) pre-treatment, but it has neglectable influence on oxygen precipitation for short-time annealing. It was believed that nitrogen co-doped heavily P-doped CZ-Si possesses nitrogen-related complexes that act as heterogeneous nuclei for super-saturated interstitial oxygen and then enhanced oxygen precipitation. Finally, it was found that nitrogen doping could hardly enhance oxygen precipitation in heavily P-doped CZ-Si at 1200 °C.
Co-reporter:Zhidan Zeng, Xiangyang Ma, Jiahe Chen, Deren Yang, Ingmar Ratschinski, Frank Hevroth, Hartmut S. Leipner
Journal of Crystal Growth (1 January 2010) Volume 312(Issue 2) pp:169-173
Publication Date(Web):1 January 2010
DOI:10.1016/j.jcrysgro.2009.10.030
We have investigated the effect of oxygen precipitates on dislocation motion in Czochralski silicon by the indentation technique. It is found that the gliding distances of dislocations are much smaller in samples containing a high density of oxygen precipitates in the order of 109 cm−3 than in the control samples without remarkable oxygen precipitates. Transmission electron microscopy reveals that oxygen precipitates can indeed pin the dislocations generated at high temperatures. Such a pinning effect is proved to be dependent on the density and size of oxygen precipitates. The particle strengthening mechanism is tentatively adopted to explain the suppression of dislocation motion by the oxygen precipitates in CZ silicon.
Co-reporter:Ning Du, Hui Zhang, Bingdi Chen, Xiangyang Ma and Deren Yang
Chemical Communications 2008(Issue 26) pp:NaN3030-3030
Publication Date(Web):2008/04/21
DOI:10.1039/B800401C
SnO2Nanotubes were synthesized via a one-pot redox route at room temperature, in which the Kirkendall effect is definitely responsible for the formation of hollow structures.
Co-reporter:Hui Zhang, Chuanxin Zhai, Jianbo Wu, Xiangyang Ma and Deren Yang
Chemical Communications 2008(Issue 43) pp:NaN5650-5650
Publication Date(Web):2008/10/14
DOI:10.1039/B812752B
CoFe2O4 nanorings were synthesized by a simple solvothermal process, in which Ostwald ripening was definitely responsible for the formation of hollow structures, and their ferromagnetic behavior at room temperature was observed.
Co-reporter:Wenjia Zhao, Ning Du, Chengmao Xiao, Hao Wu, Hui Zhang and Deren Yang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 34) pp:NaN13954-13954
Publication Date(Web):2014/07/02
DOI:10.1039/C4TA03238A
We demonstrate the synthesis of Ag–Si core–shell nanowall arrays via a simple displacement reaction and subsequent RF-sputtering deposition. The displacement between the Cu substrate and Ag+ leads to Ag nanowall arrays with good substrate adhesion. The Ag nanowall arrays can function as a mechanical support and an efficient electron conducting pathway for Si anode materials. These Ag–Si core–shell nanowall arrays show a discharge capacity of >1500 mA h g−1 at a current density of 2100 mA g−1 after 400 cycles. The capacity fade from 2nd to 400th cycles is only 0.1% per cycle. Moreover, cycling performance can be retained when the thickness of the Si layer increases, clearly demonstrating the superior cycling performance of Ag–Si core–shell nanowall arrays. Considering the simple and large-scale synthesis of Ag–Si core–shell nanowall arrays, this work may facilitate the commercial application of Si anode materials for Li-ion batteries.
Co-reporter:Ning Du, Hui Zhang, Xiangyang Ma and Deren Yang
Chemical Communications 2008(Issue 46) pp:NaN6184-6184
Publication Date(Web):2008/10/20
DOI:10.1039/B812695J
CNT/Au/SnO2nanotubes have been synthesized through homogeneous coating of Au and SnO2nanocrystals on carbon nanotubes (CNTs) and applied in a room-temperature CO gas sensor.
Co-reporter:Lifei Yang, Xuegong Yu, Mingsheng Xu, Hongzheng Chen and Deren Yang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 40) pp:NaN16883-16883
Publication Date(Web):2014/07/16
DOI:10.1039/C4TA02216E
Graphene-on-silicon (Gr–Si) heterojunction solar cells have recently attracted significant attention as promising candidates for low-cost photovoltaic applications. However, the power conversion efficiency of Gr–Si solar cells is generally smaller than 4% without chemical doping treatments. It is mainly limited by the low work function of Gr and high density defect states at the Gr–Si interface. Here, we have reported a new structure of Gr–Si solar cells by introducing a graphene oxide (GO) interlayer to engineer the Gr–Si interface for improving device performance. It is found that the GO interlayer can effectively increase open circuit voltage and meanwhile suppress the interface recombination of solar cells. As a result, a maximum efficiency of 6.18% can be achieved for the Gr/GO/Si solar cells, which is a new record for the pristine monolayer Gr–Si solar cell reported to date. Further, it is clarified that the Gr/GO/Si solar cell is significantly more stable than the Gr–Si solar cell with chemical doping. These results show a new route for fabricating efficient and stable chemical-doping-free Gr–Si solar cells.
Co-reporter:Bingdi Chen, Hui Zhang, Chuanxin Zhai, Ning Du, Chen Sun, Jingwen Xue, Deren Yang, Hai Huang, Bo Zhang, Qiuping Xie and Yulian Wu
Journal of Materials Chemistry A 2010 - vol. 20(Issue 44) pp:NaN9902-9902
Publication Date(Web):2010/09/14
DOI:10.1039/C0JM00594K
We developed a simple and novel layer-by-layer (LBL) assembly in combination with covalent connection strategy for the synthesis of multifunctional carbon nanotubes (CNTs)-based magnetic-fluorescent nanohybrids as multimodal cellular imaging agents for detecting human embryonic kidney (HEK) 293T cells via magnetic resonance (MRI) and confocal fluorescence imaging. Superparamagnetic iron oxide nanoparticles (SPIO) and near-infrared fluorescent CdTe quantum dots (QDs) were covalently coupled on the surface of CNTs in sequence via LBL assembly. It was indicated that the SPIO layer acted not only as a contrast agent for MRI, but also as a spacer between CdTe QDs and CNTs for prohibiting fluorescence quenching of QDs on the surface of the CNTs. The multifunctional CNT-based magnetic-fluorescent nanohybrids showed an enhanced MRI signal as contrast agent for detecting 293T cells in comparison with the pure SPIO. This is due to the magnetic coupling between the orderly arrayed SPIO, the function of CNTs for lowering the transverse relaxation and the ability of CNTs for penetrating into cells. Moreover, the multifunctional CNT-based magnetic-fluorescent nanohybrids exhibited the higher intracellular labeling efficiency due to the ability of CNTs for penetrating into cells in comparison with pure SPIO-CdTe nanoparticles.
Co-reporter:Xiaodong Pi, Zhenyi Ni, Yong Liu, Zhichao Ruan, Mingsheng Xu and Deren Yang
Physical Chemistry Chemical Physics 2015 - vol. 17(Issue 6) pp:NaN4151-4151
Publication Date(Web):2014/12/22
DOI:10.1039/C4CP05196C
When silicene is passivated by hydrogen, a bandgap occurs so that it becomes a semiconductor. Analogous to all the other semiconductors, doping is highly desired to realize the potential of hydrogen-passivated silicene (H-silicene). In the framework of density functional theory (DFT), we have studied the doping of H-silicene with boron (B) and phosphorus (P). The concentration of B or P ranges from 1.4% to 12.5%. It is found that the doping of B or P enables the indirect-bandgap H-silicene to be a semiconductor with a direct bandgap. With the increase of the concentration of B or P, both the valence band and the conduction band shift to lower energies, while the bandgap decreases. Both B- and P-doping lead to the decrease of the effective mass of holes and electrons in H-silicene. For both B- and P-doped H-silicene a subband absorption peak may appear, which blueshifts with the increase of the dopant concentration.
Co-reporter:Ning Du, Hongxuan Wu, Hui Zhang, Chuanxin Zhai, Ping Wu, Lei Wang and Deren Yang
Chemical Communications 2011 - vol. 47(Issue 3) pp:NaN1008-1008
Publication Date(Web):2010/11/09
DOI:10.1039/C0CC03498C
This study presents a large-scale synthesis of water-soluble sodium fluosilicate (Na2SiF6) nanowires, which serve as a versatile template for producing nanotubes.
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![3'H-Cyclopropa[1,9][5,6]fullerene-C60-Ih-3'-butanoic acid, 3'-phenyl-, 2-[[2-(dimethylamino)ethyl]methylamino]ethyl ester](/data/chemimg/3719300/1478675-82-9_b.png)
