Investigating the potential of lead-free Cs2AgBiI6 and Cs2AgBiBr6 double perovskites for photovoltaic applications

In the immediate past, there lies a pivotal relevance in lead-free A2B+B3+X6 halide double perovskites (HDPs), which have gained prominence as environmentally sustainable photovoltaic materials due to their favorable features such as small carrier effective masses, suitable bandgaps and low exciton binding energies. In this work, the photovoltaic performance of the environmentally friendly Cs2AgBiI6 and Cs2AgBiBr6 are assessed through the utilization of 1D Solar Cell Capacitance Simulator (SCAPS-1D) software. Various physical parameters such as defect density, electron affinity, and doping concentration are systematically investigated along with effect of thickness, operating temperature, and metal back work function, in the pursuit of optimal device performance in terms of power conversion efficiency (PCE). The simulation findings suggest that the optimal band structure of PSCs aids in the separation and transport of carriers. The device efficiency of both PSCs exhibited an improvement as the shunt resistance was increased, whereas it experienced a decline as the series resistance and operating temperature were increased. The determined PCE (%) from optimized Cs2AgBiI6 and Cs2AgBiBr6 perovskite solar cells (PSCs) are 24.11 and 18.71%, respectively. Theoretical implications of these results will be of great significance in the design and advancement of stable and efficient HDPs.