Design and Optimization of Lead-Free Cs 2 AgBi 0.75 Sb 0.25 Br 6 Perovskite Solar Cells: A Computational Investigation

Perovskite materials play a crucial role in the advancement of photovoltaic technology because of their remarkable optical, electronic and mechanical properties. This study explores the modeling and performance evaluation of lead-free double halide perovskite solar cells based on Cs 2 AgBi 0.75 Sb 0.25 Br 6 is analyzed, well-aligned bandgaps (1.80 eV) and demonstrating enhanced stability under ambient conditions. Various transparent conductive oxides (TCOs) such as ZnO, AZO, IZO, CuO and FTO, along with inorganic and organic electron transport layers (ETLs) including ZnOS, BaSnO 3 , SnS 2 , TiO 2 , PC61BM, C-60, and PCBM, are investigated. Additionally, inorganic and organic hole transport layers (HTLs) such as Spiro-OMeTAD, Cu 2 O, CuI, NiO, MoO 3 , Carbon, PTAA, O_Spiro-OMeTAD, and PBDB-T, as well as back contact metals including, Se, W, Pt, Pd Au, Cu, Ag Ni C, and Fe, are evaluated using SCAPS simulation. The parameters of the absorber layer, such as thickness, shallow uniform acceptor density, and defect density are varied for different solar cell configurations incorporating the mentioned TCOs, ETLs, HTLs, and back contact metals. Among the analyzed configurations, the inorganic ETL and HTL structure Glass/FTO/BaSnO 3 /Cs 2 AgBi 0.75 Sb 0.25 Br 6 /Cu 2 O/W demonstrates the best performance, achieving a V oc 1.77 V, J sc 18.75 mA/cm 2 , a FF 92.44%, and a PCE 30.74%. These findings emphasize the viability of lead-free double PSCs to deliver high efficiency while ensuring environmental sustainability, opening the door for their wider use in future photovoltaic applications.