Origin of Anomalous Aging in Quantum-Dot Light-Emitting Diodes: Optical Architecture Dependence

The advancement of quantum dot light-emitting diodes (QLEDs) is impeded by an anomalous aging phenomenon, the mechanistic interplay of which with device optical architectures─a fundamental issue driven by the industrial standard─has been consistently overlooked. Here, we report that a single-mode top-emitting QLED exhibits mitigated positive aging compared to its bottom-emitting counterpart, with the structural disparity primarily lying in the thickness of the top electrode. The discrepancy in positive aging correlates with divergent shifts in ZnO's Fermi level during device operation and shelf storage, which modulates the hole leakage current and above-threshold electron injection current to improve charge confinement and electroluminescence quantum efficiency. Further investigations uncovered that thickness-dependent Ag cathode diffusion leads to the extended distribution of Ag nanoclusters within the ZnO electron-transporting layer, facilitating chemical n-doping that elevates the Fermi level. These findings unveil a previously unrecognized pathway of positive aging and establish critical design principles for enhancing the stability and reliability of QLED displays.