A Close-SpaceFast Nucleation Strategy toward High-EfficiencyPerovskite Light-Emitting Diodes

Halide perovskite light-emitting diodes (PeLEDs), considered as potential candidates for future displays, face significant limitations in their external quantum efficiency (EQE) due to an uncontrollable nucleation and crystallization process. Herein, a close-space inverted annealing (CSIA) strategy is developed to achieve fast nucleation and obtain a more uniform perovskite film with larger crystal domains and much lower defect centers. The increased surficial temperature and quick solvent evaporation in the CSIA method result in the fast formation of numerous large nuclei and solvate intermediates at the initial stage, which effectively guide crystal growth into large domains, facilitated by the residual solvent. The CSIA-processed PeLED achieves a peak EQE of 25.8%, which is among the best values of near-infrared devices. Moreover, it is applicable to perovskite-emitting layers with different defect passivation agents. This straightforward approach highlights a great opportunity to boost the performance and commercialization of perovskite optoelectronic devices.