Exploration and optimization of different charge transport layers for Cs₄CuSb₂Cl₁₂ based perovskite solar cells

Recently, lead-free Cs₄CuSb₂Cl₁₂ has garnered attention as an excellent material to be used as an absorber of perovskite solar cells (PSCs). In this work, Cs₄CuSb₂Cl₁₂ absorber-based PSCs were studied and the conditions to get high performance for PSCs were investigated. Here, six different materials for electron transport layers (ETLs) and 10 different materials for hole transport layers (HTLs) were studied. A numerical approach was followed by using SCAPS-1D simulator. During the work, various device parameters of PSC were investigated such as thickness variation of the absorber and ETL layers, acceptor density variation of the absorber and HTL layers, variation of the donor density of the ETL layer, and effect of total defect density of absorber. Also, other parameters such as the impact of resistance, temperature, J-V graph, Q-E graph, and carrier generation rate at different positions of the PSCs were assessed. Among the studied 10 HTL materials, MWCNTs outperformed other studied materials, hence it was selected for further investigations. Then the structures were optimized based on the device parameters outcome, and the structure having MZO and STO ETLs both showed the maximum power conversion efficiency (PCE) of 28.23%. (Al/FTO/MZO/Cs₄CuSb₂Cl₁₂/MWCNTs/Au) the structure showed an open-circuit voltage (V_oc) of 1.249 V, short-circuit current density (J_sc) of 25.11 mA/cm² and a fill factor (FF) of 90.1%. The performance was also evaluated with respect to key electrical parameters. Optimum performance was achieved at a series resistance of 1 Ω·cm² and a shunt resistance of 1000 Ω·cm², beyond which performance gains saturated. The other best-performing STO ETL-based (Al/FTO/STO/Cs₄CuSb₂Cl₁₂/MWCNTs/Au) structure had V_oc of 1.25 V, J_sc of 25.11 mA/cm², and FF of 90.01% Under the optimized condition other structure with CdS, PC₆₁BM, SnS₂ and ZnSe ETLs showed PCE of 27.68%, 27.8%, 25.67% and 28.22%. This work gives good insights into several Cs₄CuSb₂Cl₁₂ based PSC structures and shows in the future they have great potential to be developed practically for highly efficient performances.