The aging characteristics, e.g., the evolution of efficiency and luminance of quantum-dot light-emitting diodes (QLEDs) are greatly affected by the encapsulation. When encapsulated with ultraviolet curable resin, the efficiency is increased over time, a known phenomenon termed as positive aging which remains one of the unsolved mysteries. By developing a physical model and an analytical model, we identify that the efficiency improvement is mainly attributed to the suppression of hole leakage current that is resulted from the passivation of ZnMgO defects. When further encapsulated with desiccant, the positive aging effect vanishes. To fully take the advantage of positive aging, the desiccant is incorporated after the positive aging process is completed. With the new encapsulation method, the QLED exhibits a high external quantum efficiency of 20.19% and a half lifetime of 1,267 h at an initial luminance of 2,800 cd·m⁻², which are improved by 1.4 and 6.0 folds, respectively, making it one of the best performing devices. Our work provides an in-depth and systematic understanding of the mechanism of positive aging and offers a practical encapsulation way for realizing efficient and stable QLEDs.

封装极大地影响了老化特性，例如量子点发光二极管（QLED）的效率和亮度的演变。当用紫外线固化树脂封装时，效率会随时间增加，这是一种称为正老化的已知现象，至今仍是未解之谜之一。通过建立物理模型和分析模型，我们发现效率的提高主要归因于ZnMgO缺陷钝化导致的空穴泄漏电流的抑制。当进一步用干燥剂封装时，积极的老化作用消失了。为了充分利用正老化的优势，在正老化过程完成后加入干燥剂。采用新的封装方法，QLED的外部量子效率高达20。^-2分别提高了1.4倍和6.0倍，使其成为性能最好的设备之一。我们的工作提供了对正老化机理的深入和系统的理解，并为实现高效稳定的QLED提供了实用的封装方法。