Combined DFT, SCAPS-1D, and wxAMPS frameworks for design optimization of efficient Cs₂BiAgI₆-based perovskite solar cells with different charge transport layers

In this study, combined DFT, SCAPS-1D, and wxAMPS frameworks are used to investigate the optimized designs of Cs₂BiAgI₆ double perovskite-based solar cells. First-principles calculations are employed to investigate the structural stability, optical responses, and electronic contribution of the constituent elements in Cs₂BiAgI₆ absorber material, where SCAPS-1D and wxAMPS simulators are used to scrutinize different configurations of Cs₂BiAgI₆ solar cells. Here, PCBM, ZnO, TiO₂, C₆₀, IGZO, SnO₂, WS₂, and CeO₂ are used as ETL, and Cu₂O, CuSCN, CuSbS₂, NiO, P3HT, PEDOT:PSS, spiro-MeOTAD, CuI, CuO, V₂O₅, CBTS, CFTS are used as HTL, and Au is used as a back contact. About ninety-six combinations of Cs₂BiAgI₆-based solar cell structures are investigated, in which eight sets of solar cell structures are identified as the most efficient structures. Besides, holistic investigation on the effect of different factors such as the thickness of different layers, series and shunt resistances, temperature, capacitance, Mott-Schottky and generation-recombination rates, and J-V (current-voltage density) and QE (quantum efficiency) characteristics is performed. The results show CBTS as the best HTL for Cs₂BiAgI₆ with all eight ETLs used in this work, resulting in a power conversion efficiency (PCE) of 19.99%, 21.55%, 21.59%, 17.47%, 20.42%, 21.52%, 14.44%, 21.43% with PCBM, TiO₂, ZnO, C₆₀, IGZO, SnO₂, CeO₂, WS₂, respectively. The proposed strategy may pave the way for further design optimization of lead-free double perovskite solar cells.