Effect of post-annealing on thermally evaporated reduced-dimensional perovskite LEDs

Reduced-dimensional perovskites (RDPs) with self-assembled multi-quantum well structures have emerged as promising candidates for light-emitting diodes (LEDs) due to their high color purity, high photoluminescence quantum yield, and decent stability. Compared to the traditional RDP film preparation methods reported in the previous literature, thermal evaporation is an appealing option for RDP film fabrication with uniform crystallization, high repeatability, and precise control. Here, based on the vacuum deposition method, we adopted a combined strategy, including annealing treatment and device structure optimization. Meanwhile, we investigated the effects of post-annealing on charge carrier recombination kinetics, exciton energy transfer, and phase distribution of vacuum-deposited RDP films. As a result, we achieved an external quantum efficiency of 6.5% for the device, which is one of the best performances among prevailing research on vacuum-processed RDP-based LEDs.