Eliminating Positive Aging in Quantum Dot Light‐Emitting Diodes by H2O‐Treatment

Abstract Quantum dot light‐emitting diodes (QLEDs) usually exhibit a positive aging phenomenon with their efficiency and brightness increase after storage for several days. Although positive aging enhances device performance, its random and uncontrollable process presents substantial challenges for QLED industrialization. Here, It is identified that the H 2 O, produced by the reaction between the acidic resin and ZnMgO, can slowly passivate the defects of ZnMgO and is thus responsible for the positive aging. By intentionally introducing H 2 O to treat the ZnMgO and post‐annealing the devices, the ZnMgO defects can be fully passivated soon after the devices are fabricated. As a result, the fresh devices exhibit a high efficiency of 55.2 lm W −1 (26%), which is 2.04 (1.67)‐fold higher than those of untreated devices and 1.21 (1.02)‐fold higher than those of untreated devices after positive aging. Moreover, the performance of the treated devices remains very stable even after storage for several days, indicating the undesired positive aging is completely eliminated. The developed in situ H 2 O treatment strategy, which enables the realization of high performance QLEDs and the elimination of uncontrollable positive aging, can promote the industrialization process of QLEDs.