Passivating SnO₂/Perovskite Interface via Multisite Chelation for High-Efficiency Perovskite Solar Cells

In n-i-p perovskite solar cells (PSCs) with tin oxide (SnO2) as the electron transport layer, the SnO2/perovskite interface serves dual functions: facilitating charge extraction and promoting perovskite crystal growth. However, significant nonradiative recombination, energy misalignment, and suboptimal interfacial bonding at the SnO2/perovskite interface result in efficiency loss and compromised stability. In this work, sulfonyl diimidazole (SDI) was introduced as a surface modifier for SnO2. SDI acts as a dual-modifier at the buried interface, binding strongly to both the SnO2 and perovskite layers. SDI effectively passivates SnO2 surface defects, optimizes band arrangement for better interfacial contact, and facilitates perovskite growth. This effectively promotes charge carrier transport, inhibits charge carrier recombination, and alleviates the film strain. The SDI-incorporated device demonstrated an improved power conversion efficiency (PCE) of 23.31%, surpassing the control device’s efficiency of 21.61%, alongside an elevation in fill factor from 77.3% to 81.56%. The optimized device demonstrates a 90% retention of its initial PCE after enduring 1000 h of aging, significantly outlasting the pristine SnO2-based counterpart. Consequently, the modification of interfaces utilizing SDI represents a viable approach to enhance the interface characteristics, elevate the quality of crystallization, and achieve high-performance PSCs.