Optimization of CsSnI ₃ -, MASnI ₃ -, and MAGeI ₃ -Based All-Perovskite Solar Cells for Cost-Effective and Nontoxic Energy Conversion

In this study, we present an all-perovskite solar cell design that replaces conventional, costly transport layers with CsSnI₃, MASnI₃, and MAGeI₃. Using SCAPS-1D simulations, we systematically optimized key physical parameters, including layer thickness, doping density, defect density, electron affinity, temperature, series resistance, and metal work function, to maximize device performance. Our analysis shows that these materials serve as cost-effective, nontoxic alternatives to traditional HTMs, absorbers, and ETMs, while delivering high efficiency. Among the various back contact options evaluated, nickel (Ni) was identified as the most economical choice without compromising efficiency. The optimized device featuring Ni as the back contact exhibits an open-circuit voltage (<i>V</i> _oc) of 0.97 V, a short-circuit current density (<i>J</i> _sc) of 35.16 mA/cm², a fill factor (FF) of 82.92%, and a power conversion efficiency (PCE) of 28.28%. This work demonstrates the potential of all-perovskite solar cells as a viable route toward low-cost and environmentally friendly energy conversion solutions.