Fabrication of Conductive Perovskite-Additive Networks Via Sequential Vacuum Deposition for Perovskite Light-Emitting Diodes

Abstract

Thermally evaporated perovskite light-emitting diodes (PeLEDs) have emerged as promising candidates for next-generation displays owing to the high reproducibility and scalability of thermal evaporation. However, the performance of thermally evaporated PeLEDs remains inferior to that of solution-processed PeLEDs. In this study, conductive perovskite-additive networks are fabricated through multisource sequential vacuum deposition using CsBr, PbBr2, and bis[2-[(oxo)diphenylphosphino] phenyl] ether (DPEPO). The phosphine oxide group in DPEPO retards crystal growth during crystallization, thereby reducing the grain size, increasing the exciton binding energy and decreasing the defect density. The enhanced electron mobility of the target perovskite device is attributable to the reduced trap density and pi-pi* stacking and upward shift of the Fermi level, which result in improved charge transport. The target perovskite device exhibits a remarkable external quantum efficiency of 16.91% and an operational half-lifetime of 191 h at 100 cd m-2, representing the highest reported values for thermally evaporated PeLEDs.