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Cu2ZnSn(S,Se)4 (CZTSSe) thin‐film solar cells offer various advantages including excellent optical and electrical properties, nontoxic and earth‐abundant raw materials, and a simple fabrication process. However, these devices suffer from a high deficit of the open‐circuit voltage (VOC), mainly caused by interface recombination, which increases with increasing surface roughness. In this study, to achieve a high VOC and enhance the overall device performance, an additional heat treatment process was introduced during the fabrication of co‐electrodeposited rough CZTSSe solar cells, and its effect on the photovoltaic properties was systematically investigated using various characterization techniques including diode analysis, transient photovoltage decay measurement, evaluation of the temperature dependency of the open‐circuit voltage, current–voltage and drive‐level capacitance profile analysis, and electrochemical impedance spectroscopy. At the optimized post‐heat treatment (PHT) temperature of 200°C, a significant increase in the conversion efficiency (as high as 32%, from 7.11% to 9.40%) was observed owing to the change in the interfacial materials properties (i.e., higher conductivity and reduced interfacial nonradiative recombination), which in turn is a consequence of the diffusion of the Cd ions and the expansion of the Cu‐poor/Zn‐rich phase. The PHT‐applied CZTSSe device exhibited a high conversion efficiency close to the record‐high one reported for electrodeposited CZTSSe thin‐film solar cells. These findings confirm the potential of PHT to overcome the serious VOC deficit of CZTSSe device; moreover, this approach could possibly be extended to other device fabrication processes to achieve higher device performance and adopted to commercialization. [ABSTRACT FROM AUTHOR]

A highly efficient Cu2ZnSn(S,Se)4 (CZTSSe)-based thin-film solar cell (9.9 %) was prepared using an electrochemical deposition method followed by thermal annealing. The Cu-Zn-Sn alloy films was grown on a Mo-coated glass substrate using a one-pot electrochemical deposition process, and the metallic precursor films was annealed under a mixed atmosphere of S and Se to form CZTSSe thin films with bandgap energies ranging from 1.0 to 1.2 eV. The compositional modification of the S/(S+Se) ratio shows a trade-off effect between the photocurrent and photovoltage, resulting in an optimum bandgap of roughly 1.14 eV. In addition, the increased S content near the p-n junction reduces the dark current and interface recombination, resulting in a further enhancement of the open-circuit voltage. As a result of the compositional and interfacial modification, the best CZTSSe-based thin-film solar cell exhibits a conversion efficiency of 9.9 %, which is among the highest efficiencies reported so far for electrochemically deposited CZTSSe-based thin-film solar cells. [ABSTRACT FROM AUTHOR]

Highly efficient copper-zinc-tin-selenide (Cu2ZnSnSe4; CZTSe) thin-film solar cells are prepared via the electrodepostion technique. A metallic alloy precursor (CZT) film with a Cu-poor, Zn-rich composition is directly deposited from a single aqueous bath under a constant current, and the precursor film is converted to CZTSe by annealing under a Se atmosphere at temperatures ranging from 400 °C to 600 °C. The crystallization of CZTSe starts at 400 °C and is completed at 500 °C, while crystal growth continues at higher temperatures. Owing to compromises between enhanced crystallinity and poor physical properties, CZTSe thin films annealed at 550 °C exhibit the best and most-stable device performances, reaching up to 8.0 % active efficiency; among the highest efficiencies for CZTSe thin-film solar cells prepared by electrodeposition. Further analysis of the electronic properties and a comparison with another state-of-the-art device prepared from a hydrazine-based solution, suggests that the conversion efficiency can be further improved by optimizing parameters such as film thickness, antireflection coating, MoSe2 formation, and p-n junction properties. [ABSTRACT FROM AUTHOR]

Abstract: Chalcopyrite CIS or CIGS have been regarded as promising absorbing materials for thin-film solar cells with widespread commercialization prospects. The most critical material properties of a CIS absorption layer that affect the overall PV performance include its microstructure and composition at a given bandgap energy. In this study, dense CISe films with high crystallinity and uniform, flat surfaces were fabricated on In2Se3/ITO employing single bath electrochemical deposition by adjusting the deposition parameters, such as the precursor concentration, pH, and applied potential. A simple formula is presented based on Faraday''s law to quantitatively estimate the density of the electrodeposited thin films; from this, it was found that the as-deposited films had a very high relative density of 0.73. The high green density of the as-deposited film led to the full densification of the CISe film with ca. 10μm sized grains. The binary selenide phase remaining in the sintered film was subsequently etched out using a KCN solution, resulting in an overall Cu-deficient composition in the film of [Cu]/[In]=0.95. [Copyright &y& Elsevier]

Graphical abstract Highlights • A thin IrO 2 film is uniformly coated on porous Ti mesh via anodic electrodeposition. • The IrO 2 film is an efficient catalyst layer for the oxygen evolution reaction. • A high current density (0.97 A cm−2 at 1.6 V) at 0.4 mg cm−2 is produced at 120 °C. • The electrodeposited film physically blocks exposure of the Ti diffusion layer. • The IrO 2 film protects against Ti corrosion and improves cell durability at 120 °C. Abstract In this study, IrO 2 -coated Ti mesh (e-IrO 2 /Ti) is proposed to be an efficient and durable oxygen electrode for high-temperature polymer-membrane-electrolyte water electrolyzers (HT-PEMWEs). A thin IrO 2 film of submicron thickness was uniformly coated onto a porous Ti mesh substrate by anodic electrodeposition. The electrodeposited IrO 2 film plays the dual role of a catalyst layer for the oxygen evolution reaction (OER), and a corrosion-protection layer that prevents oxidation of the inner Ti. The e-IrO 2 /Ti exhibited high performance (0.97 A cm−2 at 1.6 V) despite a low IrO 2 loading (0.4 mg cm−2) in single-cell tests conducted at 120 °C, which is comparable to that of conventional electrodes with greater catalyst loadings (0.8–5 mg cm−2). Furthermore, corrosion polarization tests reveal that the IrO 2 coating physically blocks exposure of the Ti diffusion layer, thereby reducing Ti corrosion by 82% in 0.5 M H 2 SO 4 at 25 °C. The low degradation rate (1.5 mA cm‐2 h−1 (0.11% h−1)) obtained in aging experiments at 120 °C and 1.72 V (voltage efficiency of 85%) confirms the excellent stability of this electrode. [ABSTRACT FROM AUTHOR]

Exploiting inexhaustible free energy from the sun to produce clean and sustainable fuels is an attractive route toward the heavily polluted earth and energy shortage. Photoelectrochemical cell is strategic energy device because the generated fuels can be stored and used on-demand. Herein, we present the fabrication of Si photoelectrodes with efficient charge separation and transfer using metal-insulator-semiconductor heterostructures for energy-rich fuel production via photoelectrochemical water and urea oxidation. With controls of the native SiO x insulator layer and catalytic NiFe metal layer, Si photoelectrode exhibits a photovoltage of 530 mV and a photocurrent density of 33.3 mA cm−2 at 1.23 V versus reversible hydrogen electrode. Further employed Ni(OH) 2 catalysts allow Si photoanode to achieve fill factor of 25.73% and solar-to-hydrogen conversion efficiency of 10.8% with a perovskite/Si tandem solar cell. The fabricated Ni(OH) 2 /NiFe/n-Si photoanode shows considerable performances toward urea oxidation. Our work presents new insights into sunlight-assisted hydrogen production using wastewater. [Display omitted] • Tailored MIS photoanode based on the insulating SiOx layer, composition-controlled NiFe metal film, and Ni(OH) 2 catalyst. • Spontaneous water oxidation with STH conversion efficiency of 10.8% implemented by the PV-PEC tandem device. • Urea oxidation with a low onset potential of 0.83 V vs. RHE by the nano-heterogeneous Ni(OH) 2 /Ni 0.5 Fe 0.5 /SiO x /n-Si photoanode. [ABSTRACT FROM AUTHOR]

The effect of temperature and pressure, and diffusion layer thickness is assessed on performance of a proton exchange membrane water electrolyzers (PEMWEs) with an ultralow iridium oxide (IrO 2 ) loading (0.1 mg cm −2 ) anode prepared by electrodeposition and a Pt/C catalyzed cathode with a Pt loading of 0.4 mg cm −2 . Increasing pressure to 2.5 bar at 120 °C enhances the water electrolysis current, so the anode electrodeposited with 0.1 mg cm −2 IrO 2 gives a current density of 1.79 A cm −2 at 1.6 V, which is comparable to the conventional powder-type IrO 2 electrode with 2.0 mg cm −2 at a temperature of 120 °C and pressure of 2.5 bar. The major factors for cell performances are rationalized in terms of overpotentials, water flow rates and thickness of diffusion layers, based on polarization behavior and ac-impedance response. [ABSTRACT FROM AUTHOR]

To reduce the use of noble metals, iridium oxide (IrO 2 ) catalysts are prepared on carbon paper (CP) by electrodeposition for use as the anodes in polymer electrolyte membrane water electrolysis (PEMWE). The activities of the fabricated electrodes toward the oxygen evolution reaction are evaluated. The loading amount and morphology of the IrO 2 deposits are varied by controlling the electrodeposition potential ( E dep ) and time ( t dep ). When electrodeposited at 0.7 V, the IrO 2 loading ranges from 0.007 to 0.464 mg cm −2 ( t dep : 1 ∼ 30 min). In the PEMWE test at 90 °C, the IrO 2 /CP electrode with an IrO 2 loading of 0.1 mg cm −2 shows the highest performance (1.92 A cm −2 at 1.8 V) in which high IrO 2 utilization is achieved without significant exposure of the substrate carbon surface. The developed IrO 2 /CP electrodes provide cell performances comparable to those in previous reports with a higher IrO 2 loading, indicating markedly enhanced mass activity. [ABSTRACT FROM AUTHOR]