Enhanced Charge Transport and Energy Alignment in Perovskite Solar Cells Using PCNI2‐BTI and Inorganic Interlayers: A Theoretical Study

The electron transporting materials (ETMs) are crucial in perovskite solar cells (PSCs) as they not only allow effective electron extraction from the perovskite absorber but also dictate the nature of the subsequent layer quality. This study addresses the use of a non‐fullerene ETM (PCNI2‐BTI), a cyano‐functionalized bithiophene imide (CNI2)‐derived polymer, within a typical n‐i‐p architecture. The performance of PCNI2‐BTI as electron transport layer, across four different perovskite absorber compositions (such as FAPbI 3 , MAPbI 3 , CsPbI 3 , and a triple‐cation perovskite) and the compatibility with various hole transport materials (HTLs) to identify the optimal device pairing, are systematically investigated. To further improve device performance, an interface engineering strategy is applied involving IGZO, WS 2 , ZnO interlayer, which enables improved charge selectivity and energy alignment. Through this systematic device design approach, the simulated device structure yielded a high theoretical PCE of 30.46%, for FAPbI 3 ‐based perovskite solar cells. Finally, this theoretical study was further extended to lead‐free perovskite, showing the suitability of PCNI2‐BTI for FASnI 3 ‐based devices, achieving an impressive PCE of 20.31%. These results underscore the suitability of PCNI2‐BTI as a versatile, high‐performance ETM for sustainable photovoltaic applications.