Improving the photovoltaic performance of Ca3AsI3-based solar cells via interface and carrier transport engineering

Lead-free anti-perovskites have recently emerged as promising photovoltaic absorbers due to their favorable optoelectronic properties. In this work, a comprehensive numerical investigation of calcium arsenide triiodide (Ca 3 AsI 3 )-based anti-perovskite solar cells (APSCs) was performed using SCAPS-1D. A baseline FTO/TiO 2 /Ca 3 AsI 3 /Cu 2 O/Au device configuration was first established, followed by systematic screening of various electron- and hole-transport layers (ETLs and HTLs) based on band alignment and charge-extraction characteristics. The device performance was further improved through detailed parametric optimization, including absorber thickness, doping concentrations, defect density, carrier lifetime, carrier diffusion length, and contact resistances. The influence of these parameters was systematically evaluated to elucidate their effects on charge transport and recombination dynamics. Among the investigated charge transport layers (CTLs), WS 2 and MoO 3 were identified as the most effective ETL and HTL in Ca 3 AsI 3 -based APSCs. Overall, the optimized device achieves a high open-circuit voltage (V oc ) of 1.356 V, a short-circuit current density (J sc ) of 25.717 mA/cm 2 , a fill factor (FF) of 87.987%, and a power conversion efficiency (PCE) of 30.68%. These results highlight the potential of Ca 3 AsI 3 as a lead-free anti-perovskite absorber and provide insights for the design of high-performance photovoltaic devices.