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초록

Heavy metal-free quantum dot (QD)-based light-emitting diodes (QLEDs) have emerged as eco-friendly and efficient candidates for next-generation displays. However, their practical application is delayed by poor operational stability. The intrinsic degradation of the InP-based QD emissive layer (EML), a primary origin of this instability, remains insufficiently understood because direct analysis of the EML within complete device stacks is extremely challenging. Here, we elucidate the degradation processes of InP QDs and their effects on device characteristics by introducing a pre-aging strategy that selectively mimics the intrinsic EML degradation. Specifically, UV irradiation of InP-based QD solutions successfully reproduced the degradation behavior of electrically aged QD EMLs, revealing sequential degradation steps consisting of initial ligand detachment, outer-shell oxidation, and inner-shell oxidation. Furthermore, this approach decouples the effects of QD degradation from those of adjacent charge-transport layers, demonstrating that intrinsic QD deterioration modulates the current density of QLEDs and constitutes the major origin of rapid luminance loss during electrical operation. These findings provide a comprehensive mechanistic understanding of degradation in InP-based QLEDs and offer valuable insights for improving the operational stability of QLEDs.

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