Design and Performance Exploration of a Lead‐Free All‐Inorganic Hydrogenated Cs2AgBiBr6‐Based Double Perovskite Solar Cell: A Numerical Modeling Study

Lead‐free double perovskite Cs 2 AgBiBr 6 has attracted wide attention owing to its nontoxic and stable properties. Recently, hydrogenated Cs 2 AgBiBr 6 (HCABB) films have been shown to possess superior optoelectronic properties than pristine Cs 2 AgBiBr 6 , and the double perovskite solar cell (DPSC) based on the films broke the efficiency record of DPSCs as soon as it was proposed. However, its poor energy band alignment and thin absorber layer thickness prevent HCABB from realizing its full photovoltaic potential. In this article, we design a lead‐free all‐inorganic HCABB‐based DPSC for application purposes. To explore its photovoltaic potential, we numerically optimize the transport layer materials, the thickness and bulk defect density of the absorber layer, the interface defect densities, the back contact material, and the parasitic series and shunt resistances step by step for the HCABB‐based DPSC. We predict the HCABB‐based DPSC with the structure of FTO/Nb 2 O 5 /HCABB/CuI/Cu can achieve an open‐circuit voltage of 1.139 V, short‐circuit current density of 22.40 mA cm −2 , fill factor of 83.35%, and power conversion efficiency of 21.28%. Overall, our work explores the photovoltaic potential of HCABB and provides guidance for fabricating more efficient HCABB‐based DPSCs.