Optimization of preparation conditions and design of device configurations for Cu3AsS4 solar cells: a combined study of first-principles calculations and SCAPS-1D device simulations.

Abstract

Former studies have investigated the band structure and optoelectronic properties of Cu3AsS4 and suggested that it is a promising photovoltaic (PV) absorber. However, its power conversion efficiency (PCE) from experiments is still unsatisfactory and detailed experimental optimization strategies are lacking. Here, combining first-principles calculations and SCAPS-1D device simulations, we have systematically studied the optoelectronic and defect properties of Cu3AsS4 to find the suitable growth conditions and have performed various device simulations by adjusting the constituent layers to optimize the device configuration of the Cu3AsS4 solar cell. Our results demonstrated that the defect and hole concentrations can be regulated to a reasonable range as the PV absorber in metal-rich and S-poor growth environments with a low growth temperature of 500 K. Owing to the large cliff-like conduction band offset between the traditional buffer layers CdS and Cu3AsS4, the open-circuit voltage loss is large and the corresponding PCE is low. The PCE can be improved by adopting the new buffer layers with low electron affinity. The corresponding n-type transparent electrode is further optimized. Finally, the solar cell with the configuration of FTO/WO3/Cu3AsS4/Mo is suggested and its PCE can reach an optimal value of 17.82%.