Modification of the SnO₂ Electron Transporting Layer by Using Perylene Diimide Derivative for Efficient Organic Solar Cells

Recently, tin oxide (SnO₂) nanoparticles (NPs) have attracted considerable attention as the electron transporting layer (ETL) for organic solar cells (OSCs) due to their superior electrical properties, excellent chemical stability, and compatibility with low-temperature solution fabrication. However, the rough surface of SnO₂ NPs may generate numerous defects, which limits the performance of the OSCs. In this study, we introduce a perylene diimide derivative (PDINO) that could passivate the defects between SnO₂ NP ETL and the active layer. Compared with the power conversion efficiency (PCE) of the pristine SnO₂ ETL–based OSCs (12.7%), the PDINO-modified device delivers a significantly increased PCE of 14.9%. Overall, this novel composite ETL exhibits lowered work function, improved electron mobility, and reduced surface defects, thus increasing charge collection efficiency and restraining defect-caused molecular recombination in the OSC. Overall, this work demonstrates a strategy of utilizing the organic–inorganic hybrid ETL that has the potential to overcome the drawbacks of SnO₂ NPs, thereby developing efficient and stable OSCs.