Energy Barrier Alignment for Efficient Perovskite Photodetectors Consisting of PEIE Combined With PCBM Electron Transport Layer

A polyelectrolyte material of ethoxylated polyethylenimine (PEIE) was combined with the conventional electron transport material of [6, 6]-phenyl-C61-butyricacidmethylester (PCBM) as an electron transport layer (ETL), and high-performance perovskite photodetectors (PePDs) consisting of the PEIE:PCBM combination system as the ETL were fabricated. The PEIE:PCBM combined ETL could tune the energy barrier for invert injected hole charges between the interface of ETL and electrode. As a result, the reduced dark current and improved photoresponse of PePDs were realized. The results showed that the obtained devices possessed a high detectivity (D ^* ) of 4.77 × 10 ¹² Jones, which was about three folds higher than that of controlled devices with pristine PCBM ETL. Meanwhile, the PePDs exhibited excellent recovery characteristics in light/dark conversion mode. Through a series of structure, morphology, and photoelectric characterization, the detailed mechanisms for the performance improvement of PePDs are disclosed.