Efficient Perovskite Light-Emitting Diodes with Chemically Bonded Contact and Regulated Charge Behavior

Efficient charge injection and radiative recombination are essential to achieving high-performance perovskite light-emitting diodes (Pero-LEDs). However, the perovskite emission layer (EML) and the electron transport layer (ETL) form a poor physically interfacial contact and non-negligible charge injection barrier, limiting the device performance. Herein, we utilize a phosphine oxide, 2,4,6-tris[3-(diphenylphosphinyl)phenyl]-1,3,5-triazine (PO-T2T), to treat the perovskite/ETL interface and form a chemically bonded contact. Specifically, PO-T2T firmly bonds on the perovskite's surface and grain boundaries through a dative bond, effectively passivating the uncoordinated lead defects. Additionally, PO-T2T has high electron mobility and establishes an electron transport highway to bridge the ETL and EML. As a result, a maximum external quantum efficiency (EQE_max) of 22.06% (average EQE_max of 20.02 ± 1.00%) and maximum luminance (L_max) of 103286 cd m^-2 have been achieved for the champion device. Our results indicate that EML/ETL interface modifications are crucial for the fabrication of highly efficient Pero-LEDs.