Efficiency enhancement of WSe₂/In₂S₃ solar cell by numerical modeling using SCAPS

Tungsten diselenide (WSe 2 ), a transition metal dichalcogenide (TMDC) compound, is considered a promising material for application in thin film solar cells because of its high carrier transport, tunable band gap, and high absorption coefficient. In this work, solar cell structure comprising FTO/In 2 S 3 /WSe 2 is modeled using one-dimensional solar cell capacitance simulator (SCAPS-1D) software where wide bandgap widely accessible In 2 S 3 is used as a novel buffer layer instead of toxic CdS buffer layer for WSe 2 -based solar cell. The effect of thickness, doping concentrations, defect density, radiative recombination coefficient, and the electron and hole capture cross-section are analyzed and optimized. After optimizing the device, the effect of operating temperature, shunt and series resistance and back contact work function are also investigated. At an optimized WSe 2 absorber layer thickness of 1.5 µm and acceptor density of 10 17 cm −3 , efficiency of 22.53%, fill factor of 84.98%, open circuit voltage of 1.096 V, and short circuit current density of 24.18 mA/cm 2 was obtained. Additionally, a back surface field (BSF) layer comprising amorphous silicon (a-Si) of thickness 0.05 µm is introduced between the absorber layer and the back contact to lessen carrier recombination at the back surface. Therefore, the efficiency rises from 22.53% to 29.5% with a fill factor of 89.53%, open circuit voltage of 1.26 V, and short circuit current density of 26.23 mA/cm 2 . The simulation results suggest that WSe 2 -based thin-film solar cells can be designed and fabricated with high efficiency and cost advantage.