A high-efficiency CIGS solar cell design employing BaSnO₃ as ETL and CsPbI₃ as HTL for improved stability and charge transport

• SCAPS-1D simulations were used to investigate the influence of ETL and HTL material choices on the performance of CIGS solar cells. • BaSnO₃ was identified as a superior ETL due to its wide bandgap, high electron mobility, and strong thermal/chemical stability compared to conventional CdS and ZnO. • CsPbI₃ was proposed as the HTL, offering high hole mobility, excellent optoelectronic properties, and chemical robustness. • The BaSnO₃/CsPbI₃-based CIGS device achieved notable efficiency metrics: 16.41% PCE, 1.1244 V Voc, 19.76 mA/cm² Jsc, and 73.86% FF. • The novel device architecture highlights the importance of strategic material selection for enhancing both efficiency and environmental sustainability in thin-film solar technologies. The selection of the electron transport layer (ETL) and hole transport layer (HTL) has a significant impact on the performance of CIGS (Copper Indium Gallium Selenide) solar cells. In this work, we use SCAPS-1D simulation to examine how different ETL and HTL materials affect the stability and efficiency of solar cells based on CIGS. Because of its wide bandgap, high electron mobility, and superior thermal and chemical stability, BaSnO₃ emerges as a promising alternative to the conventional designs that usually use CdS and ZnO as ETL materials. Utilising its exceptional optoelectronic characteristics, high hole mobility, and chemical robustness, CsPbI₃ is presented for the HTL. BaSnO₃ and CsPbI₃ combine to create a novel device architecture that improves photovoltaic performance and environmental compatibility. Notable power conversion efficiency of 16.41%, open-circuit voltage of 1.1244 V, short-circuit current density of 19.76 mA/cm2, and fill factor of 73.86% are all displayed by the simulated solar cell. These findings demonstrate how crucial careful material selection and device architecture optimisation are to improving thin-film photovoltaic technologies' stability and efficiency. The suggested structure offers a convincing route to sustainable, next-generation solar energy solutions.