Potential of Cs₄CuSb₂Cl₁₂ Double Perovskite as an Absorber for Lead‐Free Solar Cells with Double‐Hole‐Transfer‐Layer Design

Herein, Cs 4 CuSb 2 Cl 12 double perovskite is optimized as an absorber layer for perovskite solar cells (PSCs). Special attention is given to the design of the solar cell with a single hole transfer layer (single‐HTL) or with a double hole transfer layer (double‐HTL). Optimizations for the absorber layer and HTL are performed for parameters including thickness, defect density, mobility, absorption coefficient, and capture cross section. Parameters of the solar cells, energy bands, and recombination characteristics are examined in detail, and the optimum values are determined considering practical applications. Decreased recombination and increased current flow can be established by double‐HTL design. For example, 18.26, 19.74, and 19.84% conversion efficiencies are observed when using single P3HT, Spiro‐OMeTAD, and NiO as a single‐HTL on optimized solar cell design, respectively. The valance band offset (VBO) at absorber/copper nickel tin sulfide (CNTS) and CNTS/NiO interfaces is 0.27 and 0.21 eV which is lower than the VBO of absorber/CuSbS 2 and CuSbS 2 /NiO interfaces which are 0.44 and 0.37 eV, respectively. Efficiencies reach 19.88 and 19.95% when using CuSbS 2 /NiO and CNTS/NiO double‐HTLs, respectively. Cs 4 CuSb 2 Cl 12 double perovskite absorber optimizations and double‐HTL design for PSCs introduced in this work contribute for better knowledge of such materials and designs.