Surface Modification and Defect Passivation via Concurrent UV Irradiation and Annealing for Inverted Quantum Dot Light-Emitting Diodes with Enhanced Performance

Abstract

Surface defects in the ZnO electron transport layer (ETL) pose a critical challenge for realizing high-efficiency and long-lifetime quantum dot light-emitting diodes (QLEDs). Herein, we propose a simple strategy that simultaneously enhances the performance and operational lifetime of indium phosphide-based inverted QLEDs via surface modification and defect passivation of the ZnO ETL. Concurrent irradiation with 365 nm UV light during annealing of ZnO films induces photocatalytic alcohol oxidation reactions that generate protons, which subsequently adsorb onto the surface, minimizing oxygen vacancies and facilitating the formation of hydroxyl bonds. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy revealed a simultaneous decrease in oxygen vacancies and increase in the hydroxyl group content, which correlated well with the enhanced hydrophilicity and interfacial uniformity observed in contact angle and atomic force microscopy measurements. As a result, the external quantum efficiency of QLEDs improved by approximately 26%, the operational lifetime increased by around 415%, and the photoluminescence quantum yield was also enhanced. These results indicate that the concurrent process of UV irradiation and annealing is an effective approach for inducing surface modification and defect passivation at the ZnO interface, suggesting its potential as a practical processing strategy for realizing high-efficiency, long-lifetime QLEDs.