Investigation of varied Doping of ZnO as an ETL for KSnI₃ based Perovskite Solar Cell with ETL and Absorber Thickness Optimization

Lead toxicity in PSCs necessitates exploration of lead-free alternatives where KSnI<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> emerges as a considerable option. Since, the ETL regulates the performance of the cells, this study investigates the influence of various types of doping for the ZnO as an ETL for KSnI3-based PSC through SCAPS-1D simulation. The effect of dopant type (Al, In, P) on electrical properties (Jsc, Voc, FF, PCE) was examined within the FTO/ETL/KSnI3/CuI/Au device structure. Indium-doped ZnO exhibited the highest performance, achieving a PCE of 21.84%, representing a 0.85% absolute improvement in PCE and a 4.05% relative improvement compared to the undoped ZnO reference cell (PCE = 20.99%). This demonstrates a significant efficiency gain through doping. Comparing the other dopants, Al based model also outperformed the undoped ZnO cell as it reached 21.37% PCE, but the P-doped ZnO fell behind the undoped model since it only reached 19.82% of PCE. This improvement is attributed to In-ZnO’s higher electron mobility (μe), which improvess charge transfer and minimizes recombination losses. Additionally, its optimized band alignment with the KSnI<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> absorber facilitates effective charge extraction, further boosting the power conversion efficiency (PCE) compared to Al-ZnO and P-ZnO. These findings emphasize the potential of In-doped ZnO ETLs to enhance the performance and efficiency of lead-free KSnI3-based PSCs.