A non-fullerene small molecule processed with green solvent as an electron transporting material for high efficiency p-i-n perovskite solar cells

We discovered that an alcohol soluble non-fullerene small molecule perylene diimides derivative (PDIN), which is a traditional cathode interface material, can be used as a promising electron transporting material for efficient p-i-n perovskite solar cells. Surprisingly, by using 2,2,2-Trifluoroethanol as solvent for PDIN, it can easily form high quality PDIN thin film onto the perovskite layer and overcome the erosion problem of conventional alcohol solvents such as methanol and ethanol etc. In addition, PDIN can efficiently quench the photoluminescence of perovskite layer and extract electrons from perovskite layer. Finally, a power conversion efficiency of 15.28% is achieved from the device with PDIN as electron transporting layer, which is significantly higher than the PC61BM only device. Further, we also found that the performance of the device with PDIN as electron transporting layer is not sensitive to the PDIN's thickness. These results indicate that PDIN is a promising electron transporting material for efficient p-i-n perovskite solar cells.