Strategic defect control of perovskite nanocrystallites with octylammonium iodide toward efficient red perovskite light-emitting diodes with high operative stability

Abstract

Efforts have focused on ensuring bright and reliable light emission from perovskite thin films to achieve high-performance full-color display technology in perovskite light-emitting diodes (PeLEDs). We herein suggest a multi-ligand engineering approach, incorporating octylammonium iodide (OAI) as an adjunct alkylammonium ligand to enhance the quality of quasi-2D perovskite films designed for red emission in PeLEDs. The strategic use of OAI slows down the crystallization kinetics of perovskite nanocrystallites, leading to reduced defect density and improved crystallinity in the films. Systematic characterizations cover surface morphology, photoluminescence properties, and electrical characteristics, revealing the mechanisms behind the observed enhancements. These OAI-modified perovskite films serve as the high-performance emitting layer in the red PeLEDs, demonstrating notable performance metrics: a maximum electroluminescence (EL_Max) of 962 cd m⁻², a peak external quantum efficiency (EQE) of 8.62%, and a low turn-on voltage of 1.59 V, as compared to the pristine device (EL_Max: 685.08 cd m⁻² and EQE: 0.92%). Notably, the operational stability is exceptional, with a half-lifetime of >18 hours, marking a significant advancement in reliable red PeLED technology.