Solvent-Driven Surface-State Reconstruction of ZnMgO for Stable Blue QLEDs.

Blue QLEDs face a critical challenge in balancing high luminous efficiency with operational stability, primarily due to uncontrolled electron injection and interfacial trap-assisted recombination. Here, we present a facile aqueous ZnCl2 post-treatment strategy to engineer ZnMgO (ZMO) electron transport layers (ETLs). This approach leverages a synergistic mechanism of hydrolysis-induced recrystallization and chloride-mediated surface passivation to transform defective nanocrystal films into high-quality transport layers. The treated ETLs exhibit a reconstructed crystalline morphology with reduced grain boundary density and passivated oxygen vacancies. Consequently, without any pre-aging treatment, the optimized blue QLEDs exhibited a threefold increase in both external quantum efficiency (EQE, 5.47%) and operational lifetime (T50, 5.2 × 103 h), along with a twofold enhancement in luminance (2.4x104 cd/m2), compared to the control devices. This work demonstrates a facile method to manipulate the surface and bulk properties of metal oxide ETLs, effectively mitigating efficiency roll-off and providing a strategy for commercial high-brightness display technologies.