Design of Thermodynamically Stable Lead-Free Cs2InCuCl6 Double Perovskite Solar Cells

In this work, the potential of lead-free double perovskite Cs₂InCuCl₆ (CICC) is investigated as a solar cell absorber. CICC exhibits a direct bandgap of 1.1 eV and exceptional thermodynamic stability with high decomposition enthalpies (0.4–67.4 meV atom⁻¹). Utilizing Solar Cell Capacitance Simulator software (SCAPS)-1D simulations, device architecture, including material selection, layer thicknesses, and doping concentrations, are systematically developed and optimized achieving a high open-circuit voltage (V_oc) of 0.8 V, approaching the Shockley–Queisser limit, an excellent short-circuit current density (J_sc) of 26.20 mA cm⁻², and a fill factor (FF) of 87.57%. This optimization leads to a record power conversion efficiency of 19.77% with grounds for further enhancement. The key highlight of this study is the incorporation of Mott–Schottky (MS) analysis within the simulation framework, providing unprecedented insights into interfacial charge transport and its impact on device performance. This work paves the way for advanced interface engineering in lead-free perovskite solar cells, offering a roadmap for realizing highly efficient and stable devices.