Perylene Diimide‐Based Electron‐Transporting Material for Perovskite Solar Cells with Undoped Poly(3‐hexylthiophene) as Hole‐Transporting Material

Abstract Perylene diimide‐based small molecules are widely used as intermediates of liquid crystals, owing to their high planarity and electron mobility. In this study, tetrachloroperylene diimide (TCl‐PDI) was used as a small‐molecule replacement for TiO 2 as electron‐transporting material (ETM) for planar perovskite solar cells (PVSCs). Among hole‐transporting materials (HTMs) for PVSCs, poly(3‐hexylthiophene) (P3HT) gives the devices the highest stability and reproducibility. Therefore, PVSCs with the structure of indium tin oxide (ITO)/ETM/perovskite/P3HT/MoO 3 /Ag were used to evaluate the performances of new ETMs. A reference device with compact TiO 2 and P3HT gave a reasonable power conversion efficiency (PCE) of 12.78 %, whereas the PVSC with TCl‐PDI as ETM gave an enhanced PCE of 14.73 %, which is among the highest reported values for PVSCs with undoped P3HT as the HTM. Moreover, TCl‐PDI‐based devices displayed higher stability than those based on compact TiO 2 , owing to the superior perovskite quality.