•As-cut mc-Si wafer can be isotropically etched by a two-step alkali-etch process.•Flat wafer surface benefits homogenous nanostructure and cell's performance.•Mean efficiency of N-DRE Bmc-Si cells reach 18.63%, 0.6% higher than normal ones.•Isc and Voc voltage were improved simultaneously in N-DRE Bmc-Si solar cells.•High Voc of N-DRE Bmc-Si solar cells is contributed to small dark current I0.Alkali solutions are not suitable for texturing multi-crystalline silicon (mc-Si) wafer due to the anisotropic etching. In this study, a two-step alkali-etch process is developed to form a flat surface on the wafer, which can be quickly and nearly isotropically etched by immersion in a sodium hydroxide solution, followed by a sodium hydroxide-sodium hypochlorite solution. The etching process leads to the formation of homogenous nanostructure, thereby improving the cell's repeatability and performance by simultaneously increasing its short-circuit current and open-circuit voltage.

Increasing attention has now been focused on the photoelectrochemical (PEC) hydrogen evolution as a promising route to transforming solar energy into chemical fuels. Silicon is one of the most studied PEC electrode materials, but its performance is still limited by its inherent PEC instability and electrochemical inertness toward water splitting. To achieve significant PEC activities, silicon-based photoelectrodes usually have to be coupled with proper cocatalysts, and thus, the formed semiconductor–cocatalyst interface presents a critical structural parameter in the rational design of efficient PEC devices. In this study, we directly grow nanostructured pyrite-phase nickel phosphide (NiP2) cocatalyst films on textured pn+-Si photocathodes via on-surface reaction at high temperatures. The areal loading of the cocatalyst film can be tailored to achieve an optimal balance between its optical transparency and electrocatalytic activity. As a result, our pn+-Si/Ti/NiP2 photocathodes demonstrate a great PEC onset potential of 0.41 V versus reversible hydrogen electrode (RHE), a decent photocurrent density of ∼12 mA/cm2 at the thermodynamic potential of hydrogen evolution, and an impressive operation durability for at least 6 h in 0.5 M H2SO4. Comparable PEC performance is also observed in 1 M potassium borate buffer (pH = 9.5) using this device.Keywords: acidic and neutral electrolytes; NiP2; on-surface synthesis; photoelectrochemical hydrogen evolution; silicon photocathode

TiO2 thin films were grown on solar-grade (SoG) multicrystalline silicon (mc-Si) wafers with different multiscale structures by using a liquid phase deposition (LPD) method. It was found that due to the carrier injection from mc-Si wafers, the photocatalytic activity of the TiO2 films could be expanded from the ultraviolet to the visible light region. In addition, further enhanced visible light photocatalytic properties could be achieved by introducing a nano-texture and p–n junction into the mc-Si wafer, which was ascribed to the excellent light trapping and strong carrier separating properties. Our results suggest that density-graded nanostructures applied to the TiO2 photocatalyst can enhance optical absorption, benefit carrier separation, and improve photocatalytic activity.

•Serious saw marks in DWS wafer can be eliminated by using a pre-polishing with TMAH.•Uniform pyramid texture ~3–4 um can be obtained in DWS wafer as MWSS one.•DWS sc-Si cell achieved same reflection and efficiency level ~19.15% to MWSS one.•Influence of saw-mark direction to the performance of DWS sc-Si cell can be eased.•The novel texture process for DWS wafer can be easily scaled up in PV industry.An urgent challenge to popularize diamond-wire-sawn single-crystalline silicon (DWS sc-Si) wafers to PV industry is to develop a proper texture process, specially eliminating its severe saw marks and forming uniform pyramid texture. Using a simple pre-polishing step with TMAH plus routine texture process, the saw marks as well as amorphous silicon layer are removed effectively, thus benefiting the formation of a random pyramid structure on DWS sc-Si wafers, and the texturing mechanism beyond was discussed. With new texture surface, DWS sc-Si cells demonstrated similar reflection ~5% and same efficiency level ~19.15% to the traditional multi-wire-slurry-sawn solar cells. The techniques present in this article can be easily scaled up in PV industry.

•Saw marks and amorphous layer in DWS mc-Si wafer can be removed by a MCCE process.•8.31%-efficient DWS mc-Si cell with pyramidal nanostructure texture was achieved.•Light trapping mechanism of DWS mc-Si wafer has been simulated and discussed.•Nano-texture process for DWS mc-Si cell has been verified in a pilot product line.The absence of an effective texturing technique for diamond-wire sawn multi-crystalline silicon (DWS mc-Si) solar cells has hindered commercial upgrading from traditional multi-wire slurry sawn silicon (MWSS mc-Si) solar cells. In this paper, a nano-texture technique has been developed to achieve 18.31% efficient DWS mc-Si solar cells on a pilot production line. Their unique pyramidal nanostructure, which has the most close-packed {111} surface of Si diamond crystal, not only benefits both light-trapping and electric properties but also can effectively remove the saw-marks and amorphous layer of the cells. Therefore, the short-circuit current Isc of a nano-textured DWS mc-Si solar cell is ~324 mA higher than that of a micron-textured one, while its open-circuit voltage Voc does not show an evident decrease with the increase of its surface area. The technique has paved the way for the mass production of DWS mc-Si solar cells by satisfying the exact requirements of the PV industry for high efficiency and low cost.

We report the synthesis of carbon nanotube/TiC hybrid fibers using a polymer-assisted chemical solution approach. Ti metal ions are bound to aqueous polyethyleneimine (PEI) to form precursor solution. Amphiphilic PEI with Ti easily permeates the CNT fibers. Upon annealing in a controlled atmosphere, a homogeneous TiC network is formed in the CNT fibers. The obtained CNT/TiC hybrid fibers show prominent enhancement in mechanical strength and electrical conductivity. The tensile strength and conductivity of CNT/TiC fibers can be improved to 0.67 GPa and 1650 S cm−1 at room temperature, respectively. More importantly, a tensile modulus as high as 420 GPa has been achieved for the CNT/TiC fibers. Analysis shows that the cross-linking matrix of hard TiC plays a significant role in the improvement of mechanical strength. Furthermore, the electrons are transported in the CNT/TiC fiber by a three dimensional hopping mechanism.

A nanohill structure has been fabricated on a silicon surface via a micromask formed by a radio-frequency magnetron sputtering deposition of silver nanoparticles and a following dry etching under SF6 plasma. The proposed technique does not rely on oxygen gas to eliminate the damages from oxygen plasma and to increase the lifetime of the silicon crystal. The experiments indicate that the morphology and particle size distribution of silver nanoparticles determine the reflectivity of the textured silicon wafer. Interestingly, the nanohill structure exhibits a stronger light confinement ability than the columnar one, leading to a lower reflectivity. A longer minority carrier lifetime is obtained in such nanohill structures with a lower defect concentration on the surface. This work provides a pathway to fabricating black silicon of excellent light confinement structure, which may have potential for applications in some localized surface plasmons-relevant areas.

Control of the in-plane crystallographic orientation of YBa2Cu3O7 − x (YBCO) films on (100) MgO substrates is of significant application value due to the selective enhancement of superconducting properties. In the present work, the preparation, crystallographic and superconducting properties of YBCO films deposited on MgO substrates are reported. Crystallographic in-plane orientation was realized by means of tailoring the pulsed laser deposition conditions and the use of interfacial buffering structures. Superconductiong properties were measured for films having different in-plane orienations. The results indicate that the 0° in-plane oriented films showed the highest current density of 1.62 MA/cm2 that was attributed to the elimination of high-angle grain boudaries. Additionally, the growth mechanism of YBCO films was discussed in terms of crystallographic and thermodynamic theory.Highlights► YBa2Cu3O7 − x (YBCO) films prepared on MgO by pulse laser deposition (PLD). ► Refinement of 0° in-plane orientation YBCO film. ► 45° in-plane orientation YBCO film using yttria-stabilized zirconia (YSZ) buffer layer. ► Critical current of YBCO films enhanced by reducing high-angle grain boundaries. ► YSZ layer functions as a structural link between the MgO and YBCO lattice.

Hexagonal BaFe12O19 ferrite (BaM) thin films were prepared on Si (100) substrate successfully by sol–gel technology and post annealing. The results showed the BaM phase can be formed and crystallized into c-axis textured grains even when the Fe/Ba ratio of the precursor varied from 6.5 to 9.5. However, the behavior of the saturation magnetization (Ms) and intrinsic coercivity (Hc) depended strongly on the Fe/Ba ratio and annealing temperature (Ta) varied from 700 to 900 °C. The Ms and Hc values deceased with an increase of Fe/Ba ratio, for instance, were about 290 emu/cm3 and 4,200 Oe for the Fe/Ba = 6.5 film but only 116 emu/cm3 and 2,300 Oe for the Fe/Ba = 9.5 film. The Ms and Hc values of the Fe/Ba ratio = 6.5 film increased monotonously with increasing Ta, were about 120 emu/cm3 and 2,500 Oe at Ta = 800 °C, and reached to 345 emu/cm3 and 4,600 Oe at Ta = 950 °C.

•Efficiency of Qsc-Si cell can be improved by using metal-catalyzed chemical etching technique.•Color difference among sc- and mc-Si grains can be depressed due to excellent light trapping.•Characterizes of Qsc-Si ingot showed wide difference from bottom to top.•Quality of mc-Si grains and the proportion of sc-grains are equally important for the performance of Qsc-Si cells.•A parallel subcell model is proposed to explain and improve Qsc-Si cell's performance.Seed-assisted cast quasi-single crystalline silicon (Qsc-Si) technique allows the production of efficient, low-cost solar cells. However, most of the Qsc-Si wafers still consist of single- and multi-crystalline silicon grains, which lead to difficulties when attempting to achieve high efficiency by using conventional acid or alkali texture processes. This paper highlights the fact that nano-textured Qsc-Si solar cells can reach efficiencies ranging from 18.4% to 18.9% by using the same metal-catalyzed chemical etching technique, along with a depressed color difference. A parallel sub-cell model is proposed to explain how to enhance the performance of Qsc-Si cells.

TiO2 thin films were grown on solar-grade (SoG) multicrystalline silicon (mc-Si) wafers with different multiscale structures by using a liquid phase deposition (LPD) method. It was found that due to the carrier injection from mc-Si wafers, the photocatalytic activity of the TiO2 films could be expanded from the ultraviolet to the visible light region. In addition, further enhanced visible light photocatalytic properties could be achieved by introducing a nano-texture and p–n junction into the mc-Si wafer, which was ascribed to the excellent light trapping and strong carrier separating properties. Our results suggest that density-graded nanostructures applied to the TiO2 photocatalyst can enhance optical absorption, benefit carrier separation, and improve photocatalytic activity.