Co-reporter:Cheng-Fang Liu, Yan Lin, Wen-Yong Lai, Wei Huang
Materials Letters 2017 Volume 189() pp:286-289
Publication Date(Web):15 February 2017
DOI:10.1016/j.matlet.2016.12.011
•The dependence of performance on the dielectric-semiconductor interface in pentacene-based OFETs was investigated.•The hole mobility of OFETs was enhanced from 0.43 cm2/V s to 0.72 cm2/V s when treating the substrate with OTMS versus OTS.•Flat pentacene domains with larger grain sizes and less crystal boundaries were observed for the OTS treated surface.The dependence of performance on the dielectric-semiconductor interface in pentacene-based organic field-effect transistors (OFETs) was investigated by modification of the substrate with octadecylsilane (OTS) compared with octadecyltrimethoxysilane (OTMS). The hole mobility of OFETs was enhanced from 0.43 cm2/V s to 0.72 cm2/V s when treating the substrate with OTMS versus OTS. However, the subsequent ammonia vapor did not lead to enhanced FET performance, which might be closely related to its negative influence on the pentacene growth. According to atomic force microscopy (AFM) and X-ray diffraction (XRD) measurements, flat pentacene domains with larger grain sizes and less crystal boundaries were observed for the OTS treated surface, demonstrating higher crystallinity, which may play a positive role for the charge transport and thus accounts for the improved mobility.The dependence of performance on the dielectric-semiconductor interface in pentacene-based organic field-effect transistors (OFETs) was investigated by modification of the substrate with octadecylsilane (OTS) compared with octadecyltrimethoxysilane (OTMS).
Co-reporter:Mei Fang;Jinjin Huang;Yan Zhang;Xin Guo;Xinwen Zhang;Cheng-Fang Liu;Wen-Yong Lai;Wei Huang
Materials Chemistry Frontiers 2017 vol. 1(Issue 4) pp:668-676
Publication Date(Web):2017/03/31
DOI:10.1039/C6QM00133E
A novel class of monodisperse starburst molecules (T1–T3), which are comprised of a pyrene core, four short oligofluorene arms and cyanophenyl end-cappers, were designed and synthesized to explore the influence of electron-withdrawing moieties on their optoelectronic properties. The resulting materials demonstrated high fluorescence yields and excellent thermal stability with a high degradation temperature (Td) of over 400 °C. Non-doped electroluminescent devices with the configuration of ITO/PEDOT:PSS/T1–T3/TPBI/LiF/Al exhibited highly efficient and stabilized blue electroluminescence (EL). Among all these solution-processed devices, T1 possessed the best performance with a maximum luminous efficiency (LE) of 3.52 cd A−1 at 25 mA cm−2 and a maximum brightness of 9194 cd m−2 at 10 V, resulting from the improved electron affinity due to the large content of electron-withdrawing cyanophenyl moieties in the starbursts. Notably, the net gain coefficients reached 46–55 cm−1. Moreover, the amplified spontaneous emission (ASE) threshold value remained detectable upon thermal annealing temperatures up to 230 °C for T1 and 280 °C for T2–T3. 1D DFB lasing (50% fill factor, pumped source at 375 nm) was thus obtained, demonstrating a low lasing threshold. The results confirm that the incorporation of cyanophenyl moieties as end cappers can enhance the electrical properties of pyrene-centered starbursts without substantially sacrificing their great optical gain properties, which makes this series of materials very promising for electrically pumped organic lasers.
Co-reporter:Junfeng Li;Chenglong Yang;Xuelei Peng;Qi Qi;Yonghua Li;Wen-Yong Lai;Wei Huang
Organic & Biomolecular Chemistry 2017 vol. 15(Issue 39) pp:8463-8470
Publication Date(Web):2017/10/11
DOI:10.1039/C7OB01959A
Stimuli-responsive circularly polarized luminescence (CPL) was successfully achieved through fine-tuning the conformation of a perylenyl dyad by using external stimuli. Monomer CPL was clearly detected from an inherent achiral monochromophore system in a simple perylene–carbazole dyad, and concentration-dependent CPL was observed from ‘good solvent’, giving an excimer-like CPL emission with a peak maximum at 643 nm. Moreover, the CPL bands depended on the aggregated state, which was identical to the emission changes in the THF–H2O system. It is noteworthy that the perylene–carbazole dyad emitted efficient CPL in thin films even without annealing processes. The specific perylenyl–carbazole structure plays a crucial role in CPL in response to the external environment. This novel molecular design strategy opens up a new perspective for the future development of smart CPL-active organic dyads.
Co-reporter:Dongdong Li;Wen-Yong Lai;Qiyue Shao;Wei Huang
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 20) pp:11521-11524
Publication Date(Web):2017/10/09
DOI:10.1039/C7NJ02744C
Hexagonal phase (β-) NaYF4:Yb3+,Er3+ upconversion nanocrystals have attracted great attention due to their potential applications in a variety of fields, such as biomedical imaging, labeling, and photodynamic therapy. However, the precise adjustment of the particle size of pure β-NaYF4:Yb3+,Er3+ nanocrystals (without doping), especially below 20 nm, is still a great challenge, which is critical for their biomedical utilization. In this paper, a facile methodology for regulating the size of β-NaYF4:Yb3+,Er3+ upconversion nanoparticles (UCNPs) is demonstrated by varying the relative ratio of oleic acid to rare-earth acetates. The roles of oleic acid and 1-octadecene in the synthesis of UCNPs are studied in detail and their internal mechanism for the nucleation and growth of the hexagonal UCNPs is also proposed.
Co-reporter:Dongdong Li;Wen-Yong Lai;Qiyue Shao;Wei Huang
Inorganic Chemistry Frontiers 2017 vol. 4(Issue 7) pp:1211-1214
Publication Date(Web):2017/07/11
DOI:10.1039/C7QI00216E
Ultrasmall (10.8 nm) and uniform hexagonal NaYF4:Yb3+,Er3+ upconversion nanocrystals have been successfully synthesized through a temperature oscillation technique, and the nucleation and growth processes of nanocrystals were effectively separated and controlled by simply regulating the heating procedures.
Co-reporter:Mei Fang;Jinjin Huang;Si-Ju Chang;Yi Jiang;Wen-Yong Lai;Wei Huang
Journal of Materials Chemistry C 2017 vol. 5(Issue 23) pp:5797-5809
Publication Date(Web):2017/06/15
DOI:10.1039/C7TC00185A
A novel family of rigid ladder-type oligo(p-phenylene)s with donor–π–acceptor (D–π–A) architectures (n)L-F/(n)L-Ph-F (n = 2–4) end-capped with diphenylamino and fluorophenyl/fluorine units have been designed, synthesized and explored as gain media for organic lasers. The resulting materials demonstrated excellent thermal stability with a high degradation temperature (Td) over 400 °C. The extension of the π-conjugated bridge length between the donor and acceptor units successfully depressed the crystallization tendency of oligo(p-phenylene)s, resulting in enhanced glassy temperature (Tg) and improved morphological stability in neat films. The amplified spontaneous emission (ASE) threshold (Eth) decreases with an extension in the conjugation length of the oligo(p-phenylene)s. In particular, for 4L-Ph-F with the longest conjugation length, the ASE threshold is determined to be as low as 1.97 μJ cm−2 with a high net gain coefficient over 90 cm−1 and a rather low loss coefficient of α = 2.0 cm−1. One dimensional distributed feedback (1D DFB) lasers demonstrated lasing thresholds of 5.3 nJ pulse−1 (0.44 kW cm−2, 2.2 μJ cm−2) and 1.3 nJ pulse−1 (0.1 kW cm−2, 0.5 μJ cm−2) for 4L-F (at 460 nm) and 4L-Ph-F lasers (at 471 nm), respectively. It should be noted that the Eth value of all the ladder-type samples (n)L-Ph-F (n = 2–4) remains almost the same upon increasing the annealing temperature even up to 220 °C. The high gain and low loss with excellent thermal and optical stability have rendered these rigid D–π–A ladder-type materials advantageous as robust gain media for organic lasers.
Co-reporter:Xiangchun Li;Hengbin Wang;Julia A. Schneider;Zitang Wei;Wen-Yong Lai;Wei Huang;Fred Wudl;Yonghao Zheng
Journal of Materials Chemistry C 2017 vol. 5(Issue 11) pp:2781-2785
Publication Date(Web):2017/03/16
DOI:10.1039/C7TC00263G
ortho-Functionalized perylene diimides (PDIs) display better electronic properties than their bay-substituted counterparts, yet their synthesis requires expensive catalysts. We report the regioselective 2,5,8,11-functionalization of PDI via the less commonly observed 1,4-addition of aryl Grignard reagents. This direct functionalization offers a simple and low-cost method to synthesize desirable ortho-substituted PDIs. Four tetraarylated PDIs are reported along with their electronic and optoelectronic properties. Preliminary organic photovoltaic devices using these molecules as non-fullerene acceptors showed good power conversion efficiencies (PCEs) up to 5%, a new record for an acceptor with a single PDI core.
Co-reporter:Si-Ju Chang;Xu Liu;Ting-Ting Lu;Yuan-Yuan Liu;Jin-Qiang Pan;Yi Jiang;Shuang-Quan Chu;Wen-Yong Lai;Wei Huang
Journal of Materials Chemistry C 2017 vol. 5(Issue 26) pp:6629-6639
Publication Date(Web):2017/07/06
DOI:10.1039/C7TC02008B
A set of ladder-type poly(indenofluorene)s incorporating various indenofluorene chain lengths and 2,1,3-benzothiadiazole (BT) units, namely nLF-BT (n = 2–4), have been designed, synthesized and explored as gain media for organic lasers. The thermal, photophysical, electrochemical, electroluminescence, and optical gain properties of the resulting polymers have been systematically investigated in comparison with those of their poly(9,9-dioctylfluorene-co-benzothiadiazole) counterpart (F8BT) to unravel the structure–property relationships. It was found that with an extension of the ladder indenofluorene chain length the resulting copolymers exhibited progressively enhanced optical and electrical properties with low ASE thresholds, high net gain coefficients, and boosted device efficiency. The BT units played a key role in inducing energy transfer that further stabilized the optoelectronic properties of the resulting copolymers. Single-emissive-layer organic light-emitting devices based on nLF-BT exhibited superior maximum luminance and current efficiency in comparison with those of F8BT due to the incorporation of ladder-type indenofluorene chain structures. Solution-processed non-doped films exhibited prominent amplified spontaneous emission (ASE) and lasing characteristics. The ASE activity could still be detectable even upon annealing up to 280 °C for nLF-BT (n = 2–4). In particular, a relatively low ASE threshold of 6.04 μJ cm−2 with an emission peak at 568 nm and a high optical gain coefficient of g = 84 cm−1 were recorded for 4LF-BT. Moreover, one-dimensional (1D) distributed feedback (DFB) lasers based on 4LF-BT achieved a rather low lasing threshold of 7.2 nJ pulse−1 (0.60 kW cm−2, 3.0 μJ cm−2), showing great promise as robust gain media for organic lasers. These results suggest that the novel copolymer design strategy incorporating indenofluorene and BT units is rather attractive to construct robust gain media with promising low thresholds, high net gain coefficients, and stabilized lasing properties for organic lasers.
Co-reporter:Yang Wang;Wei-Dong Xu;Jian-Dong Zhang;Lu Zhou;Gang Lei;Cheng-Fang Liu;Wen-Yong Lai;Wei Huang
Journal of Materials Chemistry A 2017 vol. 5(Issue 6) pp:2460-2465
Publication Date(Web):2017/02/07
DOI:10.1039/C6TA09530E
A small molecule/fullerene binary acceptor system was developed for achieving high performance polymer solar cells. The additional blended small molecule acceptor not only improved the utilization of solar energy, but also achieved balanced carrier mobilities, leading to a significantly enhanced power conversion efficiency (PCE) up to 9.55%.
Co-reporter:Dongdong Li;Wen-Yong Lai;Qiyue Shao;Wei Huang
RSC Advances (2011-Present) 2017 vol. 7(Issue 19) pp:11491-11495
Publication Date(Web):2017/02/13
DOI:10.1039/C7RA01564J
NaYF4:Yb3+,Er3+@SiO2@Au heterogeneous nanostructures, with the ability of integrating upconversion luminescence (UCL) and photothermal therapy as well as real-time temperature monitoring, have been successfully prepared. The UCL intensities of NaYF4:Yb3+,Er3+ nanocrystals showed an obvious reduction after gold nanoparticle attachment and gold shell coating, but it was found that they were independent of the SiO2 spacer layer thicknesses. The presence of gold nanostructures can significantly improve the photothermal conversion properties of NaYF4:Yb3+,Er3+ nanocrystals with an increased temperature up to 39 °C, while retaining their temperature sensing properties, manifesting their great potential as diagnostic and therapeutic tools for use in biomedical fields.
Co-reporter:Xiangchun Li;Chunyu Wang;Yibo Xue;Cheng Meng; Wen-Yong Lai; Wei Huang
Asian Journal of Organic Chemistry 2017 Volume 6(Issue 12) pp:1749-1754
Publication Date(Web):2017/12/01
DOI:10.1002/ajoc.201700498
AbstractA unique planar and highly π-extended scaffold, 3,8,14,19-tetrabromo-diindolotriazatruxene (4Br-DIT), was synthesized via a facile one-pot strategy. The structure of 4Br-DIT was adequately verified by MALDI-TOF mass spectrometry, 1H and 13C NMR, and single-crystal XRD analysis. A combination of thermal, optical, and electrochemical investigation confirmed the electron-rich characteristics of the resulting diindolotriazatruxene unit, showing promise as a building block to construct highly π-extended polycyclic aromatic hydrocarbons (PAHs).
Co-reporter:Huan Pang, Xinran Li, Qunxing Zhao, Huaiguo Xue, Wen-Yong Lai, Zheng Hu, Wei Huang
Nano Energy 2017 Volume 35(Volume 35) pp:
Publication Date(Web):1 May 2017
DOI:10.1016/j.nanoen.2017.02.044
•Heterogenous Co3O4-nanocube/Co(OH)2-nanosheet hybrid is prepared by a hydrothermal method.•Co3O4 nanocubes are highly uniform and are distributed on the individual Co(OH)2 nanosheets.•Unique nanostructures show significant advantages for flexible supercapacitor electrodes.A novel heterogenous Co3O4-nanocube/Co(OH)2-nanosheet hybrid is prepared by a controllable facile one-pot hydrothermal reaction. The resulting Co3O4 nanocubes are highly uniform in morphology, and are distributed uniformly on the individual Co(OH)2 nanosheets. Such unique nanostructural features show significant advantages for applications as flexible supercapacitor electrodes in terms of enhanced durability and capacitance. The as-prepared electrode has offered a large capacitance of 1164 F g−1 at 1.2 A g−1. When being paired with activated carbon, the resulting flexible all-solid-state device exhibited a maximum energy density of 9.4 mWh cm−3. It is worthwhile noting that this as-assembled device showed little capacitance decay after over 5000 cycles with 97.4% retention of its original specific capacitance. Such a high performance outperforms most metal oxides-based electrodes and shows the advantages of the hybrid strategy, which shed light on exploring robust and cheap electrode materials for high-performance flexible supercapacitors.A novel heterogenous Co3O4-nanocube/Co(OH)2-nanosheet hybrid is prepared by a controllable facile one-pot hydrothermal reaction, which shows unique nanostructural features and achieves high-performance flexible all-solid-state supercapacitors.Download high-res image (165KB)Download full-size image
Co-reporter:Yi Wan;Junfeng Li;Xuelei Peng;Chao Huang;Qi Qi;Wen-Yong Lai;Wei Huang
RSC Advances (2011-Present) 2017 vol. 7(Issue 56) pp:35543-35548
Publication Date(Web):2017/07/11
DOI:10.1039/C7RA06237K
Two novel triphenylamine-o-carborane dyads with donor–acceptor architectures were designed and synthesized. The photophysical properties were thoroughly investigated. The results demonstrated that triphenylamine-o-carborane dyads presented locally excited (LE) emission and twisted intramolecular charge transfer (TICT) induced emission in various polar solvents, in which LE emission was not dependent on the solvent polarities and TICT emission was consistent with the solvent polarities. The solvent-dependent TICT emission with a large bathochromic shift exhibited a dramatic decrease in emissive efficiency with increasing the solvent polarity. More importantly, the triphenylamine-o-carborane dyads in solid states exhibited highly efficient ICT emissions, in which the ICT characteristics were confirmed by the experimental data and the density function theory (DFT) calculation results.
Co-reporter:Cheng-Fang Liu;Cheng Cheng;Yi Jiang;Wen-Yong Lai;Wei Huang
New Journal of Chemistry (1998-Present) 2017 vol. 41(Issue 22) pp:13619-13624
Publication Date(Web):2017/11/06
DOI:10.1039/C7NJ02597A
A new class of nitrogen-containing polycyclic aromatic hydrocarbons (N-PAHs) based on naphthalene-fused triazatruxenes, named as TATNaCn (n = 1–3), were successfully designed, synthesized and characterized. During the oxidative cyclodehydrogenation, multiple dehydrocyclization molecules can be effectively separated in a single reaction, implying a stepwise ring-closing process. A combination of thermal, optical, and electrochemical characterization of these stepwise ring-closed N-PAHs was conducted to explore the influence of the ring-fusing process on the optoelectronic characteristics of N-PAHs. The absorption bands of the fused products, TATNaCn, are red-shifted compared to those of the TATNa precursor, both in dilute solution and thin solid films, suggesting enlarged π-conjugation induced by the fused rings. Furthermore, the band-gap energies of these N-PAHs are facilely modulated by varying the number of closed rings, leading to tunable emission characteristics. This method of introducing triazatruxenes to construct N-PAHs provides general guidelines for exploring novel heteroatom-doped PAHs with facilely tunable optoelectronic properties.
Co-reporter:Yuanda Jiu;Jianyun Wang;Jianpeng Yi;Cheng-Fang Liu;Xin-Wen Zhang;Wen-Yong Lai;Wei Huang
Polymer Chemistry (2010-Present) 2017 vol. 8(Issue 5) pp:851-859
Publication Date(Web):2017/01/31
DOI:10.1039/C6PY01643J
A star-shaped single-polymer system based on 7,7′-(5,5′-(9-(4-(3-hexyl-5-(7-(4-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)phenyl)-9H-carbazole-3,6-diyl)bis(4-hexylthiophene-5,2-diyl))bis(4-(4-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole) (TM) as red emissive cores, benzothiadiazole (BT) as green emissive dopants and polyfluorene (PF) as blue arms was designed, synthesized and characterized. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), photophysical, electrochemical, electroluminescence and amplified spontaneous emission (ASE) measurements were performed to unravel the structure–properties relationship of the resulting polymers. By modulating the doping concentration of red, green and blue (RGB) emissive species carefully, high-color-quality saturated white electroluminescence (EL) was achieved with a current efficiency of 2.09 cd A−1, and Commission Internationale d'Eclairage (CIE) coordinates of (0.34, 0.33) for TM-R3G4 containing 0.03 mol% red core and 0.04 mol% green dopants. Particularly, the CIE coordinates matched well with the values of standard saturated white emission (0.33, 0.33). The saturated white EL of the devices could be mainly attributed to the incomplete energy transfer and suppressed intermolecular interactions in the star-shaped single-polymer system. Moreover, TM-R3G4 exhibited a relatively low threshold of 86.8 ± 5 μJ cm−2, showing intriguing potential as gain media for organic lasers. This study sheds light on understanding the photophysical nature of the resulting star-shaped single-polymer system with simultaneous RGB emission.
Co-reporter:Yi-Zhou Zhang;Tao Cheng;Yang Wang;Wen-Yong Lai;Huan Pang;Wei Huang
Advanced Materials 2016 Volume 28( Issue 26) pp:5242-5248
Publication Date(Web):
DOI:10.1002/adma.201600319
Co-reporter:Sizhen Cao, Lin Hao, Wen-Yong Lai, Hao Zhang, Zhou Yu, Xinwen Zhang, Xu Liu and Wei Huang
Journal of Materials Chemistry A 2016 vol. 4(Issue 21) pp:4709-4718
Publication Date(Web):11 Apr 2016
DOI:10.1039/C6TC00856A
A new highly efficient red-emitting Ir(III) complex, bis [9-(4-(2-ethylhexyloxy)phenyl)-3-(4-phenylquinolin-2-yl)-9H-carbazole] [3-(pyridin-2-yl) benzaldehyde]iridium(III) (Ir-CHO), has been synthesized and characterized to investigate the impact of the electron-withdrawing formyl group on the optoelectronic properties of the resulting Ir(III) complexes. For comparison, bis [9-(4-(2-ethylhexyloxy)phenyl)-3-(4-phenylquinolin-2-yl)-9H-carbazole] [(3-(pyridin-2-yl) phenyl) methanol] iridium(III) (Ir-OH) and fac-tris[9-(4-(2-ethylhexyloxy)phenyl)-3-(4-phenylquinolin-2-yl)-9H-carbazole] iridium(III) (Ir-PQCz) were also prepared. Remarkably, Ir-CHO-doped red organic light-emitting diodes (OLEDs) exhibited the highest performance, achieving a maximum luminance efficiency (LE) of 14.3 cd A−1 and an external quantum efficiency (EQE) of 8.4%, which were better than those of Ir-OH-doped and Ir-PQCz-doped red OLEDs. The results can be attributed to the introduction of the electron-withdrawing formyl group, which improved the electron affinity in Ir-CHO and lowered the electron-injection barrier in OLEDs based on Ir-CHO. Similarly, white OLEDs (WOLEDs) with Ir-CHO as their red emitter demonstrated an excellent high LE of 26.1 cd A−1 and an EQE of 10.9%. A combination of the thermal, photophysical, electrochemical and electroluminescence (EL) properties of these Ir(III) complexes can thus lead to a conclusion that the incorporation of the electron-withdrawing formyl-substituted phenylpyridine (ppy-CHO) can apparently improve the phosphorescence of the resulting red-emitting iridium complexes and thus the OLED performance. The results suggest a simple methodology for the rational design of efficient phosphorescent complexes for light-emitting applications.
Co-reporter:Huan Pang, Xinran Li, Bing Li, Yizhou Zhang, Qunxing Zhao, Wen-Yong Lai and Wei Huang
Nanoscale 2016 vol. 8(Issue 22) pp:11689-11697
Publication Date(Web):12 May 2016
DOI:10.1039/C6NR02267G
Dimanganese trioxide microflowers are easily obtained from a Mn(II) 8-hydroxyquinoline microcoordination after calcination in air. We also look into the possible formation mechanism of the flower-like morphology, and find that the reaction time affects the morphology of the coordination. Furthermore, the as-prepared porous Mn2O3 microflowers are made of many nanoplates which form many nanogaps and nanochannels. Interestingly, the assembled electrode based on the as-prepared porous Mn2O3 microflowers proves to be a high-performance electrode material for supercapacitors. The electrode shows a specific capacitance of 994 F g−1, which can work well even after 4000 cycles at 0.75 A g−1. More importantly, the porous Mn2O3 microflowers and activated carbons are assembled into a high-performance flexible solid-state asymmetric supercapacitor with a specific capacitance of 312.5 mF cm−2. The cycle test shows that the device can offer 95.6% capacity of the initial capacitance at 2.0 mA cm−2 after 5000 cycles with little decay. The maximum energy density of the device can achieve 6.56 mWh cm−3 and the maximum power density can also achieve 283.5 mW cm−3, which are among the best results for manganese based materials.
Co-reporter:Huan Pang, Bing Li, Qunxing Zhao, Wen-Yong Lai and Wei Huang
Journal of Materials Chemistry A 2016 vol. 4(Issue 13) pp:4840-4847
Publication Date(Web):25 Feb 2016
DOI:10.1039/C6TA00123H
Cu–Co3O4 hybrids and activated carbon were employed to fabricate flexible solid-state electrochemical energy storage devices via facile processing. The resulting flexible devices showed a large specific capacitance of 530 mF cm−2 with excellent mechanical flexibility, which offered a maximum volumetric energy density of 0.71 mW h cm−3, and delivered a maximum power density of 88.6 mW cm−3. What's more, the device showed an excellent cycling stability with only ∼5.2% decay after 6000 cycles.
Co-reporter:Tao Cheng, Yi-Zhou Zhang, Jian-Dong Zhang, Wen-Yong Lai and Wei Huang
Journal of Materials Chemistry A 2016 vol. 4(Issue 27) pp:10493-10499
Publication Date(Web):10 Jun 2016
DOI:10.1039/C6TA03537J
High-performance free-standing PEDOT:PSS electrodes with not only superior optoelectronic performance and high flexibility but also excellent electrochemical performance were successfully fabricated via facile multilayer spin-coating of a doped PEDOT:PSS solution. Superior optoelectronic performance and high electrochemical performance could be simultaneously achieved via doping PEDOT:PSS and modulating the layer numbers of the spin-coated PEDOT:PSS. Flexible and transparent all-solid-state supercapacitors with both superior electrochemical performance and relatively high optical transparency were fabricated for the first time using the resultant high-performance PEDOT:PSS films as both the current collectors and the active electrodes.
Co-reporter:Jian-Peng Yi, Li Zhao, Weidong Xu, Cheng-Fang Liu, Wen-Yong Lai and Wei Huang
Journal of Materials Chemistry A 2016 vol. 4(Issue 32) pp:7546-7553
Publication Date(Web):28 Jun 2016
DOI:10.1039/C6TC01606E
A set of pyrene-capped starburst organic emitters composed of a non-planar cross-shaped spirofluorene core (SF-PyF) and a large rigid planar pyrene core (Py-PyF) have been designed, synthesized and explored as efficient emitters for organic lasers. High photoluminescence yields and excellent thermal stability of SF-PyF and Py-PyF in neat films make them promising optical gain media. Low amplified spontaneous emission (ASE) thresholds of 6.6 μJ cm−2 (1.3 kW cm−2) at 451 nm for SF-PyF and 5.4 μJ cm−2 (1.1 kW cm−2) at 490 nm for Py-PyF were obtained (pump pulse: λp = 355 nm, 10 Hz, 5 ns). Distributed feedback (DFB) lasers based on SF-PyF and Py-PyF exhibited good performance with low thresholds (16 nJ per pulse for SF-PyF and 24 nJ per pulse for Py-PyF, respectively) and the full width at half maximum of about 0.2 nm. Surprisingly, DFB lasers integrated with SF-PyF and Py-PyF as gain media exhibited excellent ambient photostability and superior reliability even in hot water (80 °C). The excellent stability of ASE spectra, electroluminescence spectra and lasing spectra under harsh conditions manifests that the resulting pyrene-capped starburst emitters are beneficial for improving the lasing stability issues. The study sheds light on exploring robust organic gain media toward electrically pumped OSLs.
Co-reporter:Xiang-Chun Li, Chun-Yu Wang, Yi Wan, Wen-Yong Lai, Li Zhao, Meng-Fei Yin and Wei Huang
Chemical Communications 2016 vol. 52(Issue 13) pp:2748-2751
Publication Date(Web):24 Dec 2015
DOI:10.1039/C5CC09752E
A T-shaped Schiff-base triazatruxene derivative (TATNFF) was designed, synthesized, and explored as a sensitive probe to detect HCl gas by the naked eye. The remarkable color change of TATNFF with turn-on behavior in the presence of a trace amount of HCl gas was obviously observed by the naked eye, which opens up a new strategy to explore a novel set of smart responsive materials for sensing applications.
Co-reporter:Weidong Xu, Congfei Yan, Zhipeng Kan, Yang Wang, Wen-Yong Lai, and Wei Huang
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 22) pp:14293-14300
Publication Date(Web):May 20, 2016
DOI:10.1021/acsami.6b03974
A novel fulleropyrrolidine derivative, named FPNOH, was designed, synthesized, and utilized as an efficient electron-collecting (EC) layer for inverted organic solar cells (i-OSCs). The grafted diethanolamino-polar moieties can not only trigger its function as an EC interlayer, but also induce orthogonal solubility that guarantees subsequent multilayer processing without interfacial mixing. A higher power conversion efficiency (PCE) value of 8.34% was achieved for i-OSC devices with ITO/FPNOH EC electrode, compared to that of the sol–gel ZnO based reference devices with an optimized PCE value of 7.92%. High efficiency exceeding 7.7% was still achieved even for the devices with a relatively thick FPNOH film (16.9 nm). It is worthwhile to mention that this kind of material exhibits less thickness dependent performance, in contrast to widely utilized p-type conjugated polyelectrolytes (CPEs) as well as the nonconjugated polyelectrolytes (NCPEs). Further investigation on illuminating intensity dependent parameters revealed the role of FPNOH in reducing interfacial trap-induced recombination at the ITO/active layer interface.
Co-reporter:Weidong Xu;Ruidong Xia;Tengling Ye;Li Zhao;Zhipeng Kan;Yang Mei;Congfei Yan;Xin-Wen Zhang;Wen-Yong Lai;Panagiotis E. Keivanidis;Wei Huang
Advanced Science 2016 Volume 3( Issue 2) pp:
Publication Date(Web):
DOI:10.1002/advs.201500245
Three kinds of charged star-shaped conjugated macroelectrolytes, named as PhNBr, TPANBr, and TrNBr, are synthesized as electron-collecting interlayers for inverted polymer solar cells (i-PSCs). Based on these well-defined structured interlayer materials, the light soaking (LS) effect observed in i-PSCs was studied systematically and accurately. The general character of the LS effect is further verified by studying additional i-PSC devices functionalized with other common interlayers. The key-role of UV photons was confirmed by electrochemical impedance spectroscopy and electron-only devices. In addition, the ultraviolet photoelectron spectroscopy measurements indicate that the work function of the indium tin oxide (ITO)/interlayer cathode is significantly reduced after UV treatment. In these i-PSC devices the LS effect originates from the adsorbed oxygen on the ITO substrates when oxygen plasma is used; however, even a small amount of oxygen from the ambient is also enough for triggering the LS effect, albeit with a weaker intensity. Our results suggest that the effect of adsorbed oxygen on ITO needs to be considered with attention while preparing i-PSCs. This is an important finding that can aid the large-scale manufacturing of organic solar cells via printing technologies, which do not always ensure the full protection of the device electrode substrates from oxygen.
Co-reporter:Xin-Wen Zhang, Zhen-Feng Lei, Yue-Hua Chen, Ke-Yu Chen, Wei-Dong Xu, Lin Hao, Qu-Li Fan, Wen-Yong Lai and Wei Huang
RSC Advances 2016 vol. 6(Issue 13) pp:10326-10333
Publication Date(Web):14 Jan 2016
DOI:10.1039/C5RA19156D
We present the results of a systematic study of a conjugated starburst macromolecule TrOH cathode interlayer produced by solution-processing for the fabrication of highly efficient multilayered phosphorescent polymer light-emitting devices (PhPLEDs). It was found that the performance of the PhPLEDs was strongly dependent on the solvent composition of the TrOH coatings. The devices with the interlayer deposited from the mixed-solvent of water and ethanol showed much better device performance than that of the device with ethanol as solvent. From the impedance spectra of the devices and UV-vis absorption spectra of the emission layers (EMLs) treated by ethanol or mixed-solvent, the variation in device performance is mainly attributed to washing out the electron transport material in the EML due to the rinse effect. The erosion of the EML could be greatly suppressed by adding an appropriate amount of water into ethanol. The optimized green device with a maximum luminous efficiency of 23.4 cd A−1 and an external quantum efficiency of 6.7% was obtained when the ethanol:water ratio approached 7:3 (v/v). The peak efficiency of 14.6 cd A−1 was also achieved in a single emissive layer white PhPLED with a TrOH interlayer. In order to further understand the effect of the TrOH interlayer deposited from different solutions on the device performance, atomic force microscopy and contact angles were used to investigate the surface properties of the TrOH interlayer. The results indicate that the interfacial morphology is mainly controlled by the wetting characteristics of the EML and TrOH solution. The inferior device performance can be ascribed to the discontinuous TrOH film when the amount of water in TrOH solution is above 40%, which leads to the subdued electron injection from cathode into the EML.
Co-reporter:Jianpeng Yi, Jinjin Huang, Yan Lin, Cheng-Fang Liu, Tao Cheng, Yi Jiang, Wei Tang, Wen-Yong Lai and Wei Huang
RSC Advances 2016 vol. 6(Issue 55) pp:49903-49909
Publication Date(Web):11 May 2016
DOI:10.1039/C6RA07958J
The metallic effects of Ag, Al, Cu, and Au electrodes on the amplified spontaneous emission (ASE) actions of dioctyl substituted polyfluorene (PFO) have been investigated in detail. The results showed that the optical gain properties of PFO were seriously quenched by thin metallic electrodes. According to the results of photoluminescence (PL) spectra, ASE characterizations, PL decay, and PL quantum yield (PLQY), quenching effects of thin electrodes were found to follow the trend in the order of Ag < Al < Cu < Au. To restrict the quenching effects, water/alcohol-soluble cellulose acetate (CA) with relatively low optical losses was introduced as the interfacial layer between the electrode layer and the gain layer by spin-coating, leading to enhanced ASE restoration and threshold reduction. Consequently, by optimizing the thickness of CA layer, ASE restoration and even 39-fold, 40-fold, 6.3-fold, and 10-fold threshold reductions from 212 μJ cm−2, 230 μJ cm−2, 145 μJ cm−2, 212 μJ cm−2 to 5.4 μJ cm−2, 6.6 μJ cm−2, 23 μJ cm−2, 21 μJ cm−2 were obtained for Ag-based, Al-based, Cu-based, and Au-based devices, respectively.
Co-reporter:Yan Lin, Cheng-Fang Liu, Yi-Jing Song, Lei Yang, Wen-Jin Zeng, Wen-Yong Lai and Wei Huang
RSC Advances 2016 vol. 6(Issue 47) pp:40970-40974
Publication Date(Web):14 Apr 2016
DOI:10.1039/C6RA02032A
Inkjet printing is a promising technology because of the material conservation and facile patterning compared with other solution-processed techniques, facilitating the scalable fabrication and commercialization of organic electronics. In this study, organic thin-film transistors (OTFTs) based on poly(3-hexylthiophene) (P3HT) by inkjet printing were fabricated and explored by electrical analysis and morphological characterization. By optimizing the processing conditions, the comprehensive performance in terms of the field-effect mobility of inkjet-printed P3HT-based OTFTs was comparable to those of spin-coated P3HT-based OTFTs. More importantly, with the employment of an electrode buffer layer, namely Br(CH2)5N(CH3)3Br, the field-effect mobilities of both spin-coated and inkjet-printed OTFTs were improved in accordance with the expectations, resulting from the reduced contact resistance and improved film quality.
Co-reporter:Ming Sang, Sizhen Cao, Jianpeng Yi, Jinjin Huang, Wen-Yong Lai and Wei Huang
RSC Advances 2016 vol. 6(Issue 8) pp:6266-6275
Publication Date(Web):05 Jan 2016
DOI:10.1039/C5RA25530A
A set of pyrene derivatives substituted with multiple triazatruxene at the 1, 6- and 1, 3, 6, 8-positions, namely Py-2TAT and Py-4TAT, was synthesized and characterized. Their thermal, photophysical, and electrochemical properties were investigated in comparison with those of the pyrene and triazatruxene units to explore the relationship between the molecular architectures and corresponding properties. It is found that introducing a triazatruxene unit onto the rigid pyrene chromophore can effectively depress the crystalline nature of the pyrene and triazatruxene units, which endow the resulting materials with improved morphology properties, enhanced thermal stabilities, and favorable solution processiblity. Particularly, due to the integration of triazatruxene functional units, the resulting materials exhibit high-lying HOMO energy levels that are well matched with that of the PEDOT:PSS/ITO anode, leading to an improved hole-injection property. Solution-processed non-doped films exhibited prominent amplified spontaneous emission (ASE) and lasing characteristics. Low ASE thresholds of 150 nJ per pulse (1.4 kW cm−2) at 508 nm for Py-2TAT and 450 nJ per pulse (4.1 kW cm−2) at 530 nm for Py-4TAT were recorded. Consequently, one-dimensional (1D) distributed feed-back (DFB) lasers with low lasing threshold of 21 nJ per pulse (8.6 kW cm−2) was demonstrated. The selection of different combinations of grating periods and film thicknesses has provided the opportunity to fine tune the lasing wavelength of the DFB lasers in the range of 484–556 nm. The results indicated that construction of multi-substituted triazatruxene-pyrene architectures was beneficial to improving the electrical properties and thermal stabilities without largely sacrificing the optical properties, manifesting the potential of triazatruxene-functionalized pyrenes as efficient gain media for electrically pumped organic lasers.
Co-reporter:Yuehua Chen, Zhenfeng Lei, Xinwen Zhang, Shuangquan Chu, Weidong Xu, Bin Liu, Changjin Ou, Linghai Xie, Quli Fan, Wen-Yong Lai, Wei Huang
Journal of Luminescence 2016 Volume 170(Part 1) pp:50-55
Publication Date(Web):February 2016
DOI:10.1016/j.jlumin.2015.10.021
•Multilayered blue OLEDs were fabricated by solution-processing.•TrOH was used as electron injection layer.•The devices exhibit low turn-on voltages and high current efficiencies.•TrOH proves to be an efficient electron injection layer in OLEDs.Highly efficient blue organic light-emitting devices using an alcohol-soluble conjugated starburst macromolecule TrOH as electron injection layer were investigated. Multilayered OLEDs based on a blue polymer poly(9,9-dioctylfluorene) (PFO) and a blue small molecule 1,6-bis(3′,6′-bis(octyloxy)spiro [fluorene-9,9′- xanthene]-2-yl)pyrene (DOSFXPy) were fabricated by solution-processing. The devices exhibit low turn-on voltages of 3.8 V (PFO) and 3.5 V (DOSFXPy), and high current efficiencies of 4.3 cd/A (PFO) and 3.1 cd/A (DOSFXPy), respectively, which are better than those of the devices using TPBi/LiF as electron injection layer. These improved properties are attributed to the reduced barrier for electron injection by inserting a TrOH electron injection layer.
Co-reporter:Junfeng Li, Chenglong Yang, Chao Huang, Yi Wan, Wen-Yong Lai
Tetrahedron Letters 2016 Volume 57(Issue 11) pp:1256-1260
Publication Date(Web):16 March 2016
DOI:10.1016/j.tetlet.2016.02.015
The photoluminescence (PL) and circularly polarized luminescence (CPL) of ((R)-1-phenyl-N-(pyren-1-ylmethyl)ethanamine) P-R were successfully modulated via fine-tuning and precise control of excited conformation of dimer/excimer by external stimuli. The resulting aggregation-induced emission (AIE)-active material (P-R) exhibited CPL with a low dissymmetry factor (∼10−4) in monomeric form, while demonstrating a prominent CPL signal with a higher dissymmetry factor (∼10−3) in thin solid films even without annealing processes.Circularly polarized luminescence from pyrene luminogen was modulated via fine-tuning the excited conformation from fluidic solution to solid thin films.
Co-reporter:Cheng-Fang Liu, Yuanda Jiu, Jianyun Wang, Jianpeng Yi, Xin-Wen Zhang, Wen-Yong Lai, and Wei Huang
Macromolecules 2016 Volume 49(Issue 7) pp:2549-2558
Publication Date(Web):March 22, 2016
DOI:10.1021/acs.macromol.6b00020
A three-armed star-shaped single-polymer system comprising tris(4-(3-hexyl-5-(7-(4-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazol-4-yl)thiophen-2-yl)phenyl)amine (TN) as red emissive cores, benzothiadiazole (BT) as green emissive dopants, and polyfluorene (PF) as blue arms was successfully developed, in which the construction of the star-shaped architectures can depress intermolecular interactions and concentration quenching. The thermal, photophysical, electrochemical, electroluminescent, and amplified spontaneous emission (ASE) properties of the synthesized polymers are systematically investigated. The modulation of the doping concentration of TN and BT can guarantee the partial energy transfer in a star-shaped single-polymer system, further achieving saturated white emission. Consequently, a current efficiency of 2.41 cd A–1 and Commission Internationale d’Eclairage (CIE) coordinates of (0.34, 0.35) were recorded for TN-R3G4 with 0.03 mol % red core and 0.04 mol % green dopants. The saturated white emission is likely to result from the fine control of partial energy transfer and suppressed intermolecular interactions due to the construction of such a star-shaped single-polymer system. What is more, TN-R3G4 shows impressive ASE characteristics with relatively low threshold of 63 ± 5 μJ/cm2, which demonstrates the potential as gain media for organic lasing applications. Our results have provided new insights and better understanding into the photophysical and optoelectronic behaviors of the resulting star-shaped single-polymer systems with simultaneous RGB emission.
Co-reporter:Yi-Zhou Zhang, Yang Wang, Tao Cheng, Wen-Yong Lai, Huan Pang and Wei Huang
Chemical Society Reviews 2015 vol. 44(Issue 15) pp:5181-5199
Publication Date(Web):08 May 2015
DOI:10.1039/C5CS00174A
Paper-based supercapacitors (SCs), a novel and interesting group of flexible energy storage devices, are attracting more and more attention from both industry and academia. Cellulose papers with a unique porous bulk structure and rough and absorptive surface properties enable the construction of paper-based SCs with a reasonably good performance at a low price. The inexpensive and environmentally friendly nature of paper as well as simple fabrication techniques make paper-based SCs promising candidates for the future ‘green’ and ‘once-use-and-throw-away’ electronics. This review introduces the design, fabrication and applications of paper-based SCs, giving a comprehensive coverage of this interesting field. Challenges and future perspectives are also discussed.
Co-reporter:Tao Cheng;Yizhou Zhang;Wen-Yong Lai;Wei Huang
Advanced Materials 2015 Volume 27( Issue 22) pp:3349-3376
Publication Date(Web):
DOI:10.1002/adma.201405864
Flexible and stretchable electronics represent today's cutting-edge electronic technologies. As the most-fundamental component of electronics, the thin-film electrode remains the research frontier due to its key role in the successful development of flexible and stretchable electronic devices. Stretchability, however, is generally more challenging to achieve than flexibility. Stretchable electronic devices demand, above all else, that the thin-film electrodes have the capacity to absorb a large level of strain (>>1%) without obvious changes in their electrical performance. This article reviews the progress in strategies for obtaining highly stretchable thin-film electrodes. Applications of stretchable thin-film electrodes fabricated via these strategies are described. Some perspectives and challenges in this field are also put forward.
Co-reporter:Ye Tao;Xin Guo;Lin Hao;Runfeng Chen;Huanhuan Li;Yuehua Chen;Xinwen Zhang;Wei Huang
Advanced Materials 2015 Volume 27( Issue 43) pp:6939-6944
Publication Date(Web):
DOI:10.1002/adma.201503108
Co-reporter:Weidong Xu;Jianpeng Yi;Wen-Yong Lai;Li Zhao;Qi Zhang;Wenbo Hu;Xin-Wen Zhang;Yi Jiang;Ling Liu;Wei Huang
Advanced Functional Materials 2015 Volume 25( Issue 29) pp:4617-4625
Publication Date(Web):
DOI:10.1002/adfm.201501337
A family of trigonal starburst conjugated molecules (TrFPy, TrFPy, and TrF2Py) composed of a truxene core and pyrene cappers with various bridge lengths is synthesized and characterized. The incorporation of pyrene cappers successfully depress the crystallization tendency, resulting in enhanced glassy temperature and improved morphological stability of the thin films. The high photoluminescence yield in neat films and excellent thermal stability render these pyrene-capped starbursts promising lasing optical gain media. Low amplified spontaneous emission (ASE) thresholds (EthASE) of 180 nJ pulse-1 and 101 nJ pulse–1 were recorded for TrFPy and TrF2Py, respectively. One dimensional distributed feedback (1D DFB) lasers demonstrated lasing threshold of 9.3 kW/cm2 and 7.3 kW/cm2 for TrFPy (at 457 nm) and TrF2Py lasers (at 451 nm), respectively. The ASE performance of TrFPy and TrF2Py in an ambient condition was recorded with various annealing temperature (from 80 to 250 °C, 10 min). Surprisingly, TrFPy exhibited excellent ASE stability in an ambient condition, which is still detectable even after annealing at 250 °C for 10 min. The results suggest the pyrene-capped molecular design strategy is positive on improving the optical gain stability and meanwhile maintaining excellent lasing properties.
Co-reporter:Huan Pang, Yizhou Zhang, Tao Cheng, Wen-Yong Lai and Wei Huang
Nanoscale 2015 vol. 7(Issue 38) pp:16012-16019
Publication Date(Web):01 Sep 2015
DOI:10.1039/C5NR04322K
Uniform manganese hexacyanoferrate hydrate nanocubes are prepared via a simple chemical precipitation method at room temperature. Due to both micro/mesopores of the Prussian blue analogue and nanocubic structures, the manganese hexacyanoferrate hydrate nanocubes allow the efficient charge transfer and mass transport for electrolyte solution and chemical species. Thus, the manganese hexacyanoferrate hydrate nanocube electrode shows a good rate capability and cycling stability for electrochemical capacitors. Furthermore, electrodes modified with manganese hexacyanoferrate hydrate nanocubes demonstrate a sensitive electrochemical response to hydrogen peroxide (H2O2) in buffer solutions with a high selectivity.
Co-reporter:Weidong Xu, Zhipeng Kan, Tengling Ye, Li Zhao, Wen-Yong Lai, Ruidong Xia, Guglielmo Lanzani, Panagiotis E. Keivanidis, and Wei Huang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 1) pp:452
Publication Date(Web):December 15, 2014
DOI:10.1021/am506470b
A star-shaped monodisperse conjugated macroelectrolyte grafted with cationic side chains, TrNBr, was designed, synthesized, and utilized as efficient electron-collecting cathode interlayers for inverted polymer solar cells. A neutral one composed of identical star-shaped conjugated backbone, TrOH, was also investigated for comparison. The surface properties and the function as interfacial layers on modulating the work function of bottom electrode (indium tin oxide) were systematically studied. Both interfacial electron-selective materials show strongly thickness-dependent performance for inverted polymer solar cells, and the best performance could be achieved via optimizing the thickness with 2.4 nm of TrNBr and 8.7 nm of TrOH. Parallel investigations of optimized TrNBr and TrOH interlayer in inverted architecture with active blend layer of poly(3-hexylthiophene):indene–C60 bisadduct (P3HT:ICBA) demonstrated a remarkable power conversion efficiency (PCE) enhancement (PCE of 4.88% for TrNBr and 4.74% for TrOH) in comparison with those of conventional noninverted devices using Ca/Al cathodes (3.94%) and inverted devices with sol–gel ZnO buffer layer (4.21%). In addition, the inverted devices using the TrNBr and TrOH interlayer exhibited improved device stability in contrast to conventional noninverted devices using Ca/Al cathodes.Keywords: cathode interlayer; conjugated polyeletrolytes; inverted polymer solar cells; star-shaped molecule
Co-reporter:Yuan-Da Jiu, Cheng-Fang Liu, Jian-Yun Wang, Wen-Yong Lai, Yi Jiang, Wei-Dong Xu, Xin-Wen Zhang and Wei Huang
Polymer Chemistry 2015 vol. 6(Issue 46) pp:8019-8028
Publication Date(Web):28 Sep 2015
DOI:10.1039/C5PY01480H
A six-armed star-shaped single-polymer system consisting of three simultaneous emission species, 7,7′,7′′-(5,5,10,10,15,15-hexahexyl-10,15-dihydro-5H-diindeno[1,2-a:1′,2′-c]fluorene-2,7,12-triyl)tris(4-(4-(9H-carbazol-9-yl)phenyl)benzo[c] [1,2,5]thiadiazole) (TRCZ) as the green emissive core, polyfluorene (PF) as blue emissive arms and 4,7-bis(4-hexylthiophen-2-yl) benzo[c][1,2,5] thiadiazole (BBT) as red emissive dopants, has been designed and synthesized. The resulting polymers (P1–P3) exhibited excellent thermal stability and solution processability. A combination of UV-absorption, photoluminescence (PL) and electroluminescence (EL) measurements has provided an opportunity to elucidate the various properties of the polymers, which is favorable to understand the mechanism of the origin of white emission in this system. The incomplete energy transfer can be realized by adjusting the doping concentration of different components in the single-polymer system, facilitating white emission in a facile way. Thus, by means of modulating the doping concentration of TRCZ and BBT, P1–P3 are found to exhibit high-color-quality and stable white EL. For P2 with suitable doping contents, a single-emissive-layer device exhibited a promising white EL performance with a luminous efficiency (LE) of 1.45 cd A−1, an external quantum efficiency (EQE) of 1.37% and saturated Commission Internationale d'Eclairage (CIE) coordinates of (0.33, 0.33), which matches exactly with the standard white color. The comparative experimental results further confirm that the performance of this six-armed single-polymer system is superior to that of the linear single-polymer system and the polymer-blend system in terms of color purity and stability. The achievement of pure and stable white emission is mainly attributed to the multi-armed hyperbranched structures, which play an important role in fine controlling the incomplete energy transfer as well as preventing intermolecular interactions and phase separation in a star-shaped single-polymer system.
Co-reporter:Xinwen Zhang, Xin Guo, Yuehua Chen, Jianyun Wang, Zhenfeng Lei, Wenyong Lai, Quli Fan, Wei Huang
Journal of Luminescence 2015 Volume 161() pp:300-305
Publication Date(Web):May 2015
DOI:10.1016/j.jlumin.2015.01.035
•Solution processed high efficiency red phosphorescent OLEDs.•Small molecule mixed host system exhibits good device performances.•A maximum current efficiency of 19.9 cd/A was obtained in the device.•Mixed-host structure was utilized to obtain better charge carrier balance.Highly efficient solution-processed red phosphorescent organic light-emitting devices were developed using 4,4′,4″-tris (N-carbazolyl)-triphenylamine (TCTA) blended with 4,4′-bis-(carbazol-9-yl)biphenyl (CBP) as a mixed-host for the emitting layer. The performances of the fabricated devices made with different mixing ratios of host materials were investigated, and were found to depend on the mixing ratios. Under the optimal TCTA:CBP ratio (3:7), the maximum luminous efficiency of the device reached 19.9 cd/A, corresponding to external quantum efficiency of 11.1%. Moreover, this device with the mixed-host structure shows over 50% enhanced efficiency compared with the device using CBP as the single host. These improvements were attributed to the mixed-host structure, which effectively enhanced the hole injection/transport properties and gave a good charge carrier balance.
Co-reporter:Tao Cheng;Yizhou Zhang;Yao Chen ;Wei Huang
Chinese Journal of Chemistry 2015 Volume 33( Issue 1) pp:147-151
Publication Date(Web):
DOI:10.1002/cjoc.201400518
Abstract
A rapid, simple and cost-effective polyol method has been developed for the synthesis of silver nanowires with high aspect ratio and high purity. The aspect ratios of the silver nanowires as high as ca. 1000 (average length 40 µm and some even as long as 80 µm, diameter 50–100 nm) were obtained via optimizing the reaction conditions. Transparent electrodes with excellent optoelectronic performances (optical transmittance of 90%, sheet resistance of 23.2 Ω/□ and optical transmittance of 87%, sheet resistance of 19.7 Ω/□) comparable to commercial ITO were fabricated via simple spin coating the resulting silver nanowires onto the glass substrates. The high optoelectronic performances and the facile all-solution process of the as-prepared transparent electrodes render them rather promising candidates for use in cost-effective large-area optoelectronic devices.
Co-reporter:Yua Jiu;Jianyun Wang;Chengfang Liu;Lingling Zhao;Xiangchun Li;Yi Jiang;Weidong Xu;Xinwen Zhang;Wei Huang
Chinese Journal of Chemistry 2015 Volume 33( Issue 8) pp:873-880
Publication Date(Web):
DOI:10.1002/cjoc.201500308
Abstract
A four-armed star-shaped single-polymer system with 4,7-bis(5-(4-(9H-carbazol-9-yl)phenyl)-4-hexylthiophen-2-yl)benzo[c][1,2,5]thiadiazole (FTBT) as a red emissive core, polyfluorene (PF) as blue emissive arms and 1,3-benzo thiadiazole (BT) as green emissive dopants was designed and synthesized, in which red, green, and blue (RGB) emission balance can be achieved by adjusting the doping concentration of FTBT and BT discreetly. A typical single-emissive-layer device (ITO/PEDOT:PSS/polymer/TPBI/LiF/Al) was studied and discussed, realizing a pure and stable white emission with a luminous efficiency (LE) of 1.59 cd·A−1 and CIE coordinates of (0.31, 0.34). The high-color-quality white electroluminescence of the devices could be mainly attributed to the suppressed intermolecular interactions, and partial energy transfer from the blue PF arms to the red and green dopants.
Co-reporter:Li Zhao, Cheng-Fang Liu, Wei-Dong Xu, Yi Jiang, Wen-Yong Lai, and Wei Huang
The Journal of Physical Chemistry B 2015 Volume 119(Issue 22) pp:6730-6739
Publication Date(Web):May 18, 2015
DOI:10.1021/acs.jpcb.5b02851
A novel series of donor–acceptor star-shaped conjugated macroelectrolytes (CMEs), denoted as 4FTs, including anionic carboxylic acid sodium groups (4FNaT), neutral diethanolamine groups (4FNOHT), and cationic ammonium groups (4FNBrT), were designed, synthesized, and explored as an excellent platform to investigate the impact of various polar pendent groups on self-assembly behaviors. The resulting CMEs with donor–acceptor star-shaped architectures exhibited distinct light-harvesting properties. The interactions between 4FTs and TrNBr, a star-shaped monodisperse CME grafted with cationic quaternary ammonium side chains, were investigated in H2O and CH3OH using steady-state, time-resolved fluorescence, dynamic light scattering (DLS), and transmission electron microscopy (TEM). Highly favored energy transfer has been proven by the excellent spectral overlap between TrNBr fluorescence and 4FTs absorptions which can be tuned by adjusting the pendent polar groups and solvents. It is suggested that self-assembled structures are formed between TrNBr and 4FNaT, while there is no obvious change for TrNBr/4FNOHT and TrNBr/4FNBrT in both H2O and CH3OH at low concentrations (<10–6 M). This result is confirmed by the change of the TrNBr and 4FTs fluorescence properties and the time-resolved fluorescence data. The overall results manifest that at low concentrations the self-assembly between TrNBr and 4FTs is dominated by the electrostatic interactions. This study suggests that the functionalization of pendent polar groups of star-shaped CMEs has proven to be effective to modulate the self-assembly behaviors in dilute solutions and thus provide a strategy to further manage the optoelectronic properties.
Co-reporter:Huan Pang, Yizhou Zhang, Wen-Yong Lai, Zheng Hu, Wei Huang
Nano Energy 2015 Volume 15() pp:303-312
Publication Date(Web):July 2015
DOI:10.1016/j.nanoen.2015.04.034
•Lamellar K2Co3(P2O7)2·2H2O nanocrystal whiskers are synthesized for the first time.•Inkjet printing was utilized to make a flexible solid-state device.•The assembled micro-device exhibits a high specific capacitance (6.0 F cm−3).•The device exhibits good rate/flexibility stability and long-cycling stability.•The device exhibits a maximun energy density of 0.96 mW h cm−3.A flexible all-solid-state asymmetric micro-supercapacitor based on lamellar (K2Co3(P2O7)2·2H2O) nanocrystal whiskers and graphene nanosheets was successfully fabricated by inkjet printing in a simple and cost-effective way. A facile method to synthesize lamellar K2Co3(P2O7)2·2H2O nanocrystal whiskers under a mild hydrothermal condition was also established. The assembled micro-device exhibited a high specific capacitance (6.0 F cm−3), good rate/mechanical stability and a long cycling stability (5000 cycles) with a maximun energy density of 0.96 mW h cm−3, demonstrating great promise for applications in flexible all-solid-state micro-supercapacitors.
Co-reporter:Yi Jiang
The Journal of Physical Chemistry C 2015 Volume 119(Issue 50) pp:28117-28126
Publication Date(Web):November 27, 2015
DOI:10.1021/acs.jpcc.5b09719
A new series of pyrenyl-capped benzofiurene derivatives (PFP-1, PFP-2, PFP-3, and PFP-4) were designed, synthesized, and investigated as model compounds for understanding the effects of flexible side chains on modulating the functional properties of organic semiconductors for optoelectronics. The resulting compounds exhibited high fluorescence yields (changing from 28% for PFP-1 to 46% for PFP-3), good thermal stability (increasing from 439 °C for PFP-4 to 510 °C for PFP-1), and fair glass-transition temperatures (ranging from 84 °C for PFP-4 to 175 °C for PFP-1). According to ultraviolet absorption (UV) and photoluminescence (PL) spectra, the long flexible side chains on diaryl substituents have played an important role on influencing the intermolecular interactions and radiative deactivation decays. Moreover, the flexible side chains on diaryl substituents also influence the process of exciton migration and exciton quenching, further resulting in different photoluminescence quantum yield (PLQY) and transient lifetimes for PFP-X. As evidenced by atomic force microscopy (AFM) images and X-ray diffraction (XRD) patterns, an increase in the lengths of flexible chain substituents can effectively depress the crystalline nature of the rigid conjugated molecular backbone, which can endow the corresponding materials with improved morphology properties. The solution-processed nondoped organic light-emitting diodes (OLEDs) based on PFP-3 showed high efficiency (up to 2.56 cd/A and 8372 cd/m2) and bright blue-light emission with Commission Intermationale de L’Eclairage (CIE) coordinates of (0.15, 0.15). It is worthwhile to mention that the performance of these solution-processed OLEDs is comparable to and even better than that of vacuum-deposited OLEDs. One-dimensional (1D) distributed feedback lasers using PFP-3 as gain media were constructed with a tunable wavelength ranging from 456.0 to 471.4 nm and low pump energy thresholds (0.28 KW/cm2), which is among the best results achieved from small molecular gain media. This study emphasizes that subtle structural alteration even for flexible side chains can significantly affect the corresponding characteristics, which are vital for rational design of the molecular structures for optoelectronic applications.
Co-reporter:Tao Cheng, Yi-Zhou Zhang, Wen-Yong Lai, Yao Chen, Wen-Jin Zeng and Wei Huang
Journal of Materials Chemistry A 2014 vol. 2(Issue 48) pp:10369-10376
Publication Date(Web):23 Oct 2014
DOI:10.1039/C4TC01959H
Silver nanowires (AgNWs) with high aspect ratio are usually prepared via complicated multi-step procedures or by a relatively tedious polyol method with the assistance of Xa−/O2 (Xa− represents the halide ion or sulfion) etching. In this paper, silver nanowires with both a high aspect ratio of 800–1600 and high purity were prepared via a simple, cost-effective, high-yield and eco-friendly method without the introduction of external halides or sulfides. Embedding the as-prepared silver nanowires beneath the surface of the poly(dimethylsiloxane) (PDMS) substrate, novel stretchable AgNW/PDMS electrodes with superior comprehensive performances were fabricated. The resulting AgNW/PDMS electrodes show high optoelectronic performance. Without annealing, transparent conductive films with both high conductivity and transmittance, Rs = 14 Ω □−1, T = 90% and Rs = 9 Ω □−1, T = 81% were fabricated, respectively. To the best of our knowledge, they are among the best AgNW/PDMS electrodes in terms of transparency and electrical conductivity. The transparent electrodes also possess excellent electromechanical performance and stretchability (no obvious changes in sheet resistance with strain up to 20%). What is more, the conductive layer of the as-prepared electrodes shows strong adhesion to the substrates, demonstrating their superior durability. They also show high flexibility, good chemical stability and high uniformity.
Co-reporter:Yi-Zhou Zhang, Yang Wang, Ye-Lei Xie, Tao Cheng, Wen-Yong Lai, Huan Pang and Wei Huang
Nanoscale 2014 vol. 6(Issue 23) pp:14354-14359
Publication Date(Web):25 Sep 2014
DOI:10.1039/C4NR04782F
Porous hollow Co3O4 with rhombic dodecahedral structures were prepared by the calcination of ZIF-67 ([Co(mim)2; mim = 2-methylimidazolate]) rhombic dodecahedral microcrystals. A supercapacitor was successfully constructed by adopting the resulting porous hollow Co3O4 rhombic dodecahedral structure as the electrode material, which showed a large specific capacitance of 1100 F g−1 and retained more than 95.1% of the specific capacitance after 6000 continuous charge–discharge cycles. The excellent capacitive properties and stability mark the porous hollow Co3O4 with the rhombic dodecahedral structure as one of the most promising electrode materials for high-performance supercapacitors.
Co-reporter:Fang Wang, Xiang-Chun Li, Wen-Yong Lai, Yao Chen, Wei Huang, and Fred Wudl
Organic Letters 2014 Volume 16(Issue 11) pp:2942-2945
Publication Date(Web):May 22, 2014
DOI:10.1021/ol501083d
A facile one-pot tetramerization of indolin-2-one with phosphoryl chloride was applied for the first convenient direct synthesis of C2v-symmetric cyclooctatetraindole with an 8π annulene as the center. Tetra- and octa-arylated cyclooctatetraindole derivatives functionalized with fluorescent fluorene and pyrene units were thus facilely synthesized and characterized.
Co-reporter:Wei-Dong Xu, Wen-Yong Lai, Qi Hu, Xiao-Yun Teng, Xin-Wen Zhang and Wei Huang
Polymer Chemistry 2014 vol. 5(Issue 8) pp:2942-2950
Publication Date(Web):09 Jan 2014
DOI:10.1039/C3PY01477K
We present the design and synthesis of a hydrophilic monodisperse conjugated starburst macromolecule, TrOH, grafted with diethanolamine groups on its side chains, as efficient electron transport/injection layer (ETL) for solution-processed organic light emitting diodes (OLEDs), which allows the use of high work-function metal Al as the cathode instead of the use of conventional environmentally unstable cathode. Multilayer OLEDs with device configuration of ITO/PEDOT:PSS/emissive layer/TrOH/Al have been facilely constructed by solution processing due to the orthogonal solubility of the ETL and the active layer. For comparison, devices with Al, Ca/Al cathodes and a conjugated polymer grafted with the same polar pendant groups (PFN-OH) as ETL with Al as cathode have also been fabricated. The device based on TrOH/Al cathode showed superior luminous efficiency (LE) of 3.01 cd A−1 to those using Al cathode (0.08 cd A−1), Ca/Al cathode (1.32 cd A−1) and PFN-OH/Al (2.00 cd A−1). In order to understand the role of hydrophilic TrOH as ETL on improving the device performance, open-circuit voltage (Voc) of the devices, the water contact angles (θ), and atomic force microscopy (AFM) were used to investigate the surface properties before and after deposition of ETL. The results confirmed that the electron injection barrier from the Al electrode could be effectively decreased by inserting hydrophilic TrOH as ETL. The uniform well-defined nanostructured surface morphology of TrOH appeared to be an important factor for improving device performance, which will likely have a positive effect on improving interface contact and/or increase the local electric field intensity. This study thus opens a broad idea on designing highly efficient ETL materials with monodisperse characteristics and novel molecular topology for organic electronics.
Co-reporter:Weidong Xu, Xinwen Zhang, Qi Hu, Li Zhao, Xiaoyun Teng, Wen-Yong Lai, Ruidong Xia, Jenny Nelson, Wei Huang, Donal D.C. Bradley
Organic Electronics 2014 Volume 15(Issue 6) pp:1244-1253
Publication Date(Web):June 2014
DOI:10.1016/j.orgel.2014.03.029
•A hydrophilic conjugated polyfluorene was synthesized and utilized as cathode interlayer.•The influence of fine tuning the polymer backbone structures has been investigated.•The resulting polyfluorene cathode interlayers demonstrated backbone dependent performance.•For PLEDs there is a 90% increase in luminous efficiency relative to Ca/Al for PPFN-OH/Al cathode.•For PSCs there is a 19% increase in PCE relative to Ca/Al for ITO/PPFN-OH electron extraction electrodes.A hydrophilic polyfluorene-based conjugated polyelectrolyte (CPE) Poly[9,9-bis(4′-(6″-(diethanolamino)hexyloxy) phenyl)fluorene], PPFN-OH ( Scheme 1) has been synthesized and utilized as cathode interlayer for both polymer light emitting diodes (PLEDs) and solar cells (PSCs). For comparison, another CPE namely Poly[9,9-bis(6′-(diethanolamino)hexyl)fluorene] (PFN-OH) has also been investigated. They comprise the same polyfluorene backbone structures with, respectively, diethanolaminohexyl (PFN-OH) and diethanolaminohexoxyphenyl (PPFN-OH) substituents attached to the C9 carbon of the fluorene repeat unit. In comparison to reference devices with more reactive Ca/Al cathodes, utilizing these CPEs as interlayers allowed an Al cathode to be used for blue light emission PLEDs, yielding 51% and 92% enhancement of maximum luminous efficiency (LE) for PFN-OH and PPFN-OH, respectively. The PLEDs with PPFN-OH showed both higher maximum LE and maximum luminance (L) (LE = 2.53 cd/A at 6.2 V, L = 9917 cd/m2 at 8.3 V) than devices with PFN-OH (2.00 cd/A at 4.1 V, 3237 cd/m2 at 7.2 V). The PPFN-OH PLEDs also showed no significant roll-off in efficiency with increasing current density up to 400 mA/cm2, indicating excellent electron injection ability and stability for this interlayer. The insertion of alkoxy-phenyl groups at the C9-position in PPFN-OH is clearly advantageous. This simple modification significantly improves the CPE cathode interlayer performance. Parallel investigations of the electron extraction properties of PPFN-OH in inverted architecture PSCs with PCDTBT:PC70BM bulk heterojunction active layers demonstrated a power conversion efficiency enhancement of ∼19% (from 4.99% to 5.95%) for indium tin oxide cathode devices compared with reference devices using Ca/Al cathodes. These results confirm PPFN-OH to be a promising interlayer material for high performance solution processed organic optoelectronic devices.Graphical abstract
Co-reporter:Wen-Yong Lai;Dong Liu ;Wei Huang
Macromolecular Chemistry and Physics 2011 Volume 212( Issue 5) pp:445-454
Publication Date(Web):
DOI:10.1002/macp.201000499
Co-reporter:Wen-Yong Lai;Dong Liu ;Wei Huang
Macromolecular Chemistry and Physics 2011 Volume 212( Issue 5) pp:
Publication Date(Web):
DOI:10.1002/macp.201190008
Co-reporter:WenYong Lai;Dong Liu;Wei Huang
Science China Chemistry 2010 Volume 53( Issue 12) pp:2472-2480
Publication Date(Web):2010 December
DOI:10.1007/s11426-010-4152-3
Hyperbranched polymer structures represent a class of high-functionality building blocks with excellent three-dimensional topology for the construction of highly substituted conjugated polymers. In this contribution, an efficient microwave synthesis protocol toward the synthesis of conjugated hyperbranched polymers is presented. A novel series of soluble hyperbranched polyfluorenes (PTF1-PTF3) incorporating triazatruxene moiety as the branch units with various branching degrees have thus been successfully constructed with good yields and high molecular weight via a facile “A2+B2+C3” approach. The structures of the hyperbranched polymers were confirmed by NMR and GPC. Their thermal, optical, and electrochemical properties of the hyperbranched polymers were also investigated. The results showed that introduction of triazatruxene units into the hyperbranched structure endowed the polymer with good thermal stability and highly amorphous properties. Photophysical investigation of PTFx revealed strong blue emission in both solution and solid states. Hyperbranched polymers with higher degree of branching and proper content of linear fluorene units exhibited better photophysical properties in terms of narrow emission spectra and relatively high quantum efficiency as well as improved thermal spectral stability. The triazatruxene branching unit also played a role in raising the HOMO energy levels relative to those of polyfluorenes that would help to improve the charge injection and transport properties. The incorporation of triazatruxene unit into hyperbranched polymers has thus explored an effective avenue for constructing optoelectronic polymers with improved functional characteristics.
Co-reporter:Qi-Yuan He, Wen-Yong Lai, Zhun Ma, Dao-Yong Chen, Wei Huang
European Polymer Journal 2008 Volume 44(Issue 10) pp:3169-3176
Publication Date(Web):October 2008
DOI:10.1016/j.eurpolymj.2008.06.005
A novel series of soluble hyperbranched polyfluorenes P1−P6 with various branching degrees and contents of kinked carbazole units were successfully synthesized with good yields and high molecular weight via a facile “A2 + B2 + C3 + D2” approach. The thermal, optical, and electrochemical properties as well as thermal spectral stability of the resulting hypberbranched polymers were investigated. All polymers exhibited good thermal stabilities and bright blue emission in both solutions and solid-states. Hyperbranched polyfluorenes (P3 and P6) exhibited improved spectral stability upon annealing at 200 °C in air, in sharp contrast to the linear poly(9,9-dihexylfluorene) (PDHF) that showed significant additional green emission at ca. 530 nm within minutes. In particular, outstanding spectral stability was observed with carbazole-incorporating hyperbranched polyfluorene P6. Electrochemical characterization indicated that the presence of carbazole also effectively raised the HOMO level with respect to that of polyfluorene homopolymer, suggesting better hole-injection properties. Hence, the incorporation of kinked carbazole unit into hyperbranched polyfluorenes could provide a new methodology for preparing blue light-emitting polymers with improved optoelectronic characteristics.
Co-reporter:Yuehua Chen, Mengke Zhang, Xinwen Zhang, Zhenfeng Lei, Xiaolin Zhang, Lin Hao, Quli Fan, Wenyong Lai, Wei Huang
Journal of Luminescence (June 2017) Volume 186() pp:
Publication Date(Web):June 2017
DOI:10.1016/j.jlumin.2017.02.022
Efficient multilayered green phosphorescent polymer light-emitting devices (PhPLEDs) were successfully fabricated using a solution-processed n-doped small molecular electron transporting layer (ETL) composed of 1,3,5-tris(N-phenyl-benzimidazol-2-yl)-benzene (TPBi) and CsF. We found that the electroluminescence properties of the devices with n-doped ETLs are significantly improved. The maximum luminance efficiency of the device with 7.5 wt% CsF doped TPBi ETL reached 26.9 cd/A, which is 1.5 times as large as that of the undoped device. The impedance spectra of the devices and electron transport properties of the CsF doped ETLs demonstrate that doping dramatically decreases the impedance and enhances the electrical conductivity. Similarly, enhanced performance of PhPLED is also observed by use of CsF-doped 4,7-diphenyl-1,10 -phenanthroline (BPhen) ETL. These results demonstrate that CsF can be used as an effective n-dopant in solution-processed devices.
Co-reporter:Tao Cheng, Yi-Zhou Zhang, Jian-Peng Yi, Lei Yang, Jian-Dong Zhang, Wen-Yong Lai and Wei Huang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 36) pp:NaN13763-13763
Publication Date(Web):2016/08/09
DOI:10.1039/C6TA05319J
Flexible transparent PEDOT:PSS/Ag grids were inkjet printed on polyethylene terephthalate substrates. The combination of Ag grids with PEDOT:PSS not only compensates for the demerits of the single materials but also makes full use of their advantages. The Ag grids and the PEDOT:PSS layer offered extra conductive paths for each other, yielding a much lower sheet resistance of the PEDOT:PSS/Ag grids than that of either the Ag grids or the PEDOT:PSS layer, thus improving the electrochemical performance as well. The PEDOT:PSS layer could also boost the anti-oxidation capability as well as smoothen the line of the Ag grids. Various exquisite patterns of the modified PEDOT:PSS were inkjet printed on the delicate Ag grids, forming an aesthetic appearance. As a result, the PEDOT:PSS/Ag grid hybrid electrodes exhibited superior optoelectronic performance (T ∼89% and Rs ∼12 Ω sq−1), very good electrochemical energy storage behaviours, high flexibility and delicate patterns. Inkjet-printed flexible transparent all-solid-state supercapacitors have thus been constructed with both aesthetic appearance and superior electrochemical performance for the first time using the resultant PEDOT:PSS/Ag grids as both current collectors and active electrode materials.
Co-reporter:Yang Wang, Wei-Dong Xu, Jian-Dong Zhang, Lu Zhou, Gang Lei, Cheng-Fang Liu, Wen-Yong Lai and Wei Huang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 6) pp:NaN2465-2465
Publication Date(Web):2017/01/03
DOI:10.1039/C6TA09530E
A small molecule/fullerene binary acceptor system was developed for achieving high performance polymer solar cells. The additional blended small molecule acceptor not only improved the utilization of solar energy, but also achieved balanced carrier mobilities, leading to a significantly enhanced power conversion efficiency (PCE) up to 9.55%.
Co-reporter:Xiang-Chun Li, Chun-Yu Wang, Yi Wan, Wen-Yong Lai, Li Zhao, Meng-Fei Yin and Wei Huang
Chemical Communications 2016 - vol. 52(Issue 13) pp:NaN2751-2751
Publication Date(Web):2015/12/24
DOI:10.1039/C5CC09752E
A T-shaped Schiff-base triazatruxene derivative (TATNFF) was designed, synthesized, and explored as a sensitive probe to detect HCl gas by the naked eye. The remarkable color change of TATNFF with turn-on behavior in the presence of a trace amount of HCl gas was obviously observed by the naked eye, which opens up a new strategy to explore a novel set of smart responsive materials for sensing applications.
Co-reporter:Sizhen Cao, Lin Hao, Wen-Yong Lai, Hao Zhang, Zhou Yu, Xinwen Zhang, Xu Liu and Wei Huang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 21) pp:NaN4718-4718
Publication Date(Web):2016/04/11
DOI:10.1039/C6TC00856A
A new highly efficient red-emitting Ir(III) complex, bis [9-(4-(2-ethylhexyloxy)phenyl)-3-(4-phenylquinolin-2-yl)-9H-carbazole] [3-(pyridin-2-yl) benzaldehyde]iridium(III) (Ir-CHO), has been synthesized and characterized to investigate the impact of the electron-withdrawing formyl group on the optoelectronic properties of the resulting Ir(III) complexes. For comparison, bis [9-(4-(2-ethylhexyloxy)phenyl)-3-(4-phenylquinolin-2-yl)-9H-carbazole] [(3-(pyridin-2-yl) phenyl) methanol] iridium(III) (Ir-OH) and fac-tris[9-(4-(2-ethylhexyloxy)phenyl)-3-(4-phenylquinolin-2-yl)-9H-carbazole] iridium(III) (Ir-PQCz) were also prepared. Remarkably, Ir-CHO-doped red organic light-emitting diodes (OLEDs) exhibited the highest performance, achieving a maximum luminance efficiency (LE) of 14.3 cd A−1 and an external quantum efficiency (EQE) of 8.4%, which were better than those of Ir-OH-doped and Ir-PQCz-doped red OLEDs. The results can be attributed to the introduction of the electron-withdrawing formyl group, which improved the electron affinity in Ir-CHO and lowered the electron-injection barrier in OLEDs based on Ir-CHO. Similarly, white OLEDs (WOLEDs) with Ir-CHO as their red emitter demonstrated an excellent high LE of 26.1 cd A−1 and an EQE of 10.9%. A combination of the thermal, photophysical, electrochemical and electroluminescence (EL) properties of these Ir(III) complexes can thus lead to a conclusion that the incorporation of the electron-withdrawing formyl-substituted phenylpyridine (ppy-CHO) can apparently improve the phosphorescence of the resulting red-emitting iridium complexes and thus the OLED performance. The results suggest a simple methodology for the rational design of efficient phosphorescent complexes for light-emitting applications.
Co-reporter:Huan Pang, Bing Li, Qunxing Zhao, Wen-Yong Lai and Wei Huang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 13) pp:NaN4847-4847
Publication Date(Web):2016/02/25
DOI:10.1039/C6TA00123H
Cu–Co3O4 hybrids and activated carbon were employed to fabricate flexible solid-state electrochemical energy storage devices via facile processing. The resulting flexible devices showed a large specific capacitance of 530 mF cm−2 with excellent mechanical flexibility, which offered a maximum volumetric energy density of 0.71 mW h cm−3, and delivered a maximum power density of 88.6 mW cm−3. What's more, the device showed an excellent cycling stability with only ∼5.2% decay after 6000 cycles.
Co-reporter:Tao Cheng, Yi-Zhou Zhang, Jian-Dong Zhang, Wen-Yong Lai and Wei Huang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 27) pp:NaN10499-10499
Publication Date(Web):2016/06/10
DOI:10.1039/C6TA03537J
High-performance free-standing PEDOT:PSS electrodes with not only superior optoelectronic performance and high flexibility but also excellent electrochemical performance were successfully fabricated via facile multilayer spin-coating of a doped PEDOT:PSS solution. Superior optoelectronic performance and high electrochemical performance could be simultaneously achieved via doping PEDOT:PSS and modulating the layer numbers of the spin-coated PEDOT:PSS. Flexible and transparent all-solid-state supercapacitors with both superior electrochemical performance and relatively high optical transparency were fabricated for the first time using the resultant high-performance PEDOT:PSS films as both the current collectors and the active electrodes.
Co-reporter:Si-Ju Chang, Xu Liu, Ting-Ting Lu, Yuan-Yuan Liu, Jin-Qiang Pan, Yi Jiang, Shuang-Quan Chu, Wen-Yong Lai and Wei Huang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 26) pp:NaN6639-6639
Publication Date(Web):2017/06/05
DOI:10.1039/C7TC02008B
A set of ladder-type poly(indenofluorene)s incorporating various indenofluorene chain lengths and 2,1,3-benzothiadiazole (BT) units, namely nLF-BT (n = 2–4), have been designed, synthesized and explored as gain media for organic lasers. The thermal, photophysical, electrochemical, electroluminescence, and optical gain properties of the resulting polymers have been systematically investigated in comparison with those of their poly(9,9-dioctylfluorene-co-benzothiadiazole) counterpart (F8BT) to unravel the structure–property relationships. It was found that with an extension of the ladder indenofluorene chain length the resulting copolymers exhibited progressively enhanced optical and electrical properties with low ASE thresholds, high net gain coefficients, and boosted device efficiency. The BT units played a key role in inducing energy transfer that further stabilized the optoelectronic properties of the resulting copolymers. Single-emissive-layer organic light-emitting devices based on nLF-BT exhibited superior maximum luminance and current efficiency in comparison with those of F8BT due to the incorporation of ladder-type indenofluorene chain structures. Solution-processed non-doped films exhibited prominent amplified spontaneous emission (ASE) and lasing characteristics. The ASE activity could still be detectable even upon annealing up to 280 °C for nLF-BT (n = 2–4). In particular, a relatively low ASE threshold of 6.04 μJ cm−2 with an emission peak at 568 nm and a high optical gain coefficient of g = 84 cm−1 were recorded for 4LF-BT. Moreover, one-dimensional (1D) distributed feedback (DFB) lasers based on 4LF-BT achieved a rather low lasing threshold of 7.2 nJ pulse−1 (0.60 kW cm−2, 3.0 μJ cm−2), showing great promise as robust gain media for organic lasers. These results suggest that the novel copolymer design strategy incorporating indenofluorene and BT units is rather attractive to construct robust gain media with promising low thresholds, high net gain coefficients, and stabilized lasing properties for organic lasers.
Co-reporter:Xiangchun Li, Hengbin Wang, Julia A. Schneider, Zitang Wei, Wen-Yong Lai, Wei Huang, Fred Wudl and Yonghao Zheng
Journal of Materials Chemistry A 2017 - vol. 5(Issue 11) pp:NaN2785-2785
Publication Date(Web):2017/03/02
DOI:10.1039/C7TC00263G
ortho-Functionalized perylene diimides (PDIs) display better electronic properties than their bay-substituted counterparts, yet their synthesis requires expensive catalysts. We report the regioselective 2,5,8,11-functionalization of PDI via the less commonly observed 1,4-addition of aryl Grignard reagents. This direct functionalization offers a simple and low-cost method to synthesize desirable ortho-substituted PDIs. Four tetraarylated PDIs are reported along with their electronic and optoelectronic properties. Preliminary organic photovoltaic devices using these molecules as non-fullerene acceptors showed good power conversion efficiencies (PCEs) up to 5%, a new record for an acceptor with a single PDI core.
Co-reporter:Jian-Peng Yi, Li Zhao, Weidong Xu, Cheng-Fang Liu, Wen-Yong Lai and Wei Huang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 32) pp:NaN7553-7553
Publication Date(Web):2016/06/28
DOI:10.1039/C6TC01606E
A set of pyrene-capped starburst organic emitters composed of a non-planar cross-shaped spirofluorene core (SF-PyF) and a large rigid planar pyrene core (Py-PyF) have been designed, synthesized and explored as efficient emitters for organic lasers. High photoluminescence yields and excellent thermal stability of SF-PyF and Py-PyF in neat films make them promising optical gain media. Low amplified spontaneous emission (ASE) thresholds of 6.6 μJ cm−2 (1.3 kW cm−2) at 451 nm for SF-PyF and 5.4 μJ cm−2 (1.1 kW cm−2) at 490 nm for Py-PyF were obtained (pump pulse: λp = 355 nm, 10 Hz, 5 ns). Distributed feedback (DFB) lasers based on SF-PyF and Py-PyF exhibited good performance with low thresholds (16 nJ per pulse for SF-PyF and 24 nJ per pulse for Py-PyF, respectively) and the full width at half maximum of about 0.2 nm. Surprisingly, DFB lasers integrated with SF-PyF and Py-PyF as gain media exhibited excellent ambient photostability and superior reliability even in hot water (80 °C). The excellent stability of ASE spectra, electroluminescence spectra and lasing spectra under harsh conditions manifests that the resulting pyrene-capped starburst emitters are beneficial for improving the lasing stability issues. The study sheds light on exploring robust organic gain media toward electrically pumped OSLs.
Co-reporter:Tao Cheng, Yi-Zhou Zhang, Wen-Yong Lai, Yao Chen, Wen-Jin Zeng and Wei Huang
Journal of Materials Chemistry A 2014 - vol. 2(Issue 48) pp:NaN10376-10376
Publication Date(Web):2014/10/23
DOI:10.1039/C4TC01959H
Silver nanowires (AgNWs) with high aspect ratio are usually prepared via complicated multi-step procedures or by a relatively tedious polyol method with the assistance of Xa−/O2 (Xa− represents the halide ion or sulfion) etching. In this paper, silver nanowires with both a high aspect ratio of 800–1600 and high purity were prepared via a simple, cost-effective, high-yield and eco-friendly method without the introduction of external halides or sulfides. Embedding the as-prepared silver nanowires beneath the surface of the poly(dimethylsiloxane) (PDMS) substrate, novel stretchable AgNW/PDMS electrodes with superior comprehensive performances were fabricated. The resulting AgNW/PDMS electrodes show high optoelectronic performance. Without annealing, transparent conductive films with both high conductivity and transmittance, Rs = 14 Ω □−1, T = 90% and Rs = 9 Ω □−1, T = 81% were fabricated, respectively. To the best of our knowledge, they are among the best AgNW/PDMS electrodes in terms of transparency and electrical conductivity. The transparent electrodes also possess excellent electromechanical performance and stretchability (no obvious changes in sheet resistance with strain up to 20%). What is more, the conductive layer of the as-prepared electrodes shows strong adhesion to the substrates, demonstrating their superior durability. They also show high flexibility, good chemical stability and high uniformity.
Co-reporter:Yi-Zhou Zhang, Yang Wang, Tao Cheng, Wen-Yong Lai, Huan Pang and Wei Huang
Chemical Society Reviews 2015 - vol. 44(Issue 15) pp:NaN5199-5199
Publication Date(Web):2015/05/08
DOI:10.1039/C5CS00174A
Paper-based supercapacitors (SCs), a novel and interesting group of flexible energy storage devices, are attracting more and more attention from both industry and academia. Cellulose papers with a unique porous bulk structure and rough and absorptive surface properties enable the construction of paper-based SCs with a reasonably good performance at a low price. The inexpensive and environmentally friendly nature of paper as well as simple fabrication techniques make paper-based SCs promising candidates for the future ‘green’ and ‘once-use-and-throw-away’ electronics. This review introduces the design, fabrication and applications of paper-based SCs, giving a comprehensive coverage of this interesting field. Challenges and future perspectives are also discussed.
Co-reporter:Mei Fang, Jinjin Huang, Si-Ju Chang, Yi Jiang, Wen-Yong Lai and Wei Huang
Journal of Materials Chemistry A 2017 - vol. 5(Issue 23) pp:NaN5809-5809
Publication Date(Web):2017/04/13
DOI:10.1039/C7TC00185A
A novel family of rigid ladder-type oligo(p-phenylene)s with donor–π–acceptor (D–π–A) architectures (n)L-F/(n)L-Ph-F (n = 2–4) end-capped with diphenylamino and fluorophenyl/fluorine units have been designed, synthesized and explored as gain media for organic lasers. The resulting materials demonstrated excellent thermal stability with a high degradation temperature (Td) over 400 °C. The extension of the π-conjugated bridge length between the donor and acceptor units successfully depressed the crystallization tendency of oligo(p-phenylene)s, resulting in enhanced glassy temperature (Tg) and improved morphological stability in neat films. The amplified spontaneous emission (ASE) threshold (Eth) decreases with an extension in the conjugation length of the oligo(p-phenylene)s. In particular, for 4L-Ph-F with the longest conjugation length, the ASE threshold is determined to be as low as 1.97 μJ cm−2 with a high net gain coefficient over 90 cm−1 and a rather low loss coefficient of α = 2.0 cm−1. One dimensional distributed feedback (1D DFB) lasers demonstrated lasing thresholds of 5.3 nJ pulse−1 (0.44 kW cm−2, 2.2 μJ cm−2) and 1.3 nJ pulse−1 (0.1 kW cm−2, 0.5 μJ cm−2) for 4L-F (at 460 nm) and 4L-Ph-F lasers (at 471 nm), respectively. It should be noted that the Eth value of all the ladder-type samples (n)L-Ph-F (n = 2–4) remains almost the same upon increasing the annealing temperature even up to 220 °C. The high gain and low loss with excellent thermal and optical stability have rendered these rigid D–π–A ladder-type materials advantageous as robust gain media for organic lasers.
Co-reporter:Xiang-Chun Li, Chun-Yu Wang, Wen-Yong Lai and Wei Huang
Journal of Materials Chemistry A 2016 - vol. 4(Issue 45) pp:NaN10587-10587
Publication Date(Web):2016/10/07
DOI:10.1039/C6TC03832H
10,15-Dihydro-5H-diindolo[3,2-a:3′,2′-c]carbazole (triazatruxene or triindole), which is an aromatic and C3 symmetric planar π-extended conjugated structure, has attracted a great deal of interest due to its exceptional solubility, high thermal stability, rich-electronic properties and easy modification. Over the past ten years, owing to the advances in the synthesis of triazatruxene derivatives, the scope of applications of this attractive building block has been extended to organic electronics, two-photon absorption, nonlinear optics, fluorescent sensors, etc. This review aims at summarizing investigations into triazatruxene-based organic electronic materials from synthesis and self-assembly to optoelectronic properties to achieve a better understanding on the structure–function relationships and to explore their extensive applications. The potential of these highly promising scaffolds in future research will also be put forth.
Co-reporter:Dongdong Li, Wen-Yong Lai, Qiyue Shao and Wei Huang
Inorganic Chemistry Frontiers 2017 - vol. 4(Issue 7) pp:NaN1214-1214
Publication Date(Web):2017/05/25
DOI:10.1039/C7QI00216E
Ultrasmall (10.8 nm) and uniform hexagonal NaYF4:Yb3+,Er3+ upconversion nanocrystals have been successfully synthesized through a temperature oscillation technique, and the nucleation and growth processes of nanocrystals were effectively separated and controlled by simply regulating the heating procedures.
Co-reporter:Mei Fang, Jinjin Huang, Yan Zhang, Xin Guo, Xinwen Zhang, Cheng-Fang Liu, Wen-Yong Lai and Wei Huang
Inorganic Chemistry Frontiers 2017 - vol. 1(Issue 4) pp:NaN676-676
Publication Date(Web):2016/09/28
DOI:10.1039/C6QM00133E
A novel class of monodisperse starburst molecules (T1–T3), which are comprised of a pyrene core, four short oligofluorene arms and cyanophenyl end-cappers, were designed and synthesized to explore the influence of electron-withdrawing moieties on their optoelectronic properties. The resulting materials demonstrated high fluorescence yields and excellent thermal stability with a high degradation temperature (Td) of over 400 °C. Non-doped electroluminescent devices with the configuration of ITO/PEDOT:PSS/T1–T3/TPBI/LiF/Al exhibited highly efficient and stabilized blue electroluminescence (EL). Among all these solution-processed devices, T1 possessed the best performance with a maximum luminous efficiency (LE) of 3.52 cd A−1 at 25 mA cm−2 and a maximum brightness of 9194 cd m−2 at 10 V, resulting from the improved electron affinity due to the large content of electron-withdrawing cyanophenyl moieties in the starbursts. Notably, the net gain coefficients reached 46–55 cm−1. Moreover, the amplified spontaneous emission (ASE) threshold value remained detectable upon thermal annealing temperatures up to 230 °C for T1 and 280 °C for T2–T3. 1D DFB lasing (50% fill factor, pumped source at 375 nm) was thus obtained, demonstrating a low lasing threshold. The results confirm that the incorporation of cyanophenyl moieties as end cappers can enhance the electrical properties of pyrene-centered starbursts without substantially sacrificing their great optical gain properties, which makes this series of materials very promising for electrically pumped organic lasers.
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