Impact of the resistive switching effects in ZnMgO electron transport layer on the aging characteristics of quantum dot light-emitting diodes

The phenomenon of positive aging has been frequently reported in quantum dot light-emitting diodes (QLEDs). However, the root cause for this phenomenon remains illusive. On the other hand, the commonly used electron transport material in QLEDs, ZnMgO, has been extensively studied as a resistive switching material. In this work, we found that the ZnMgO nano-particle film used in QLEDs showed a clear resistive switching effect. It is, thus, reasonable to relate the resistive switching mechanism of ZnMgO to the aging characteristics of QLED devices. We found that during the first stage of QLED aging, the efficiency of the QLED was improved due to the migration of off-lattice ions and formation of conductive filaments in the ZnMgO layer. Subsequently, as active oxygen ions migrated to the interface between quantum dots and ZnMgO, the barrier for electron transport increased due to the oxidation of quantum dots. At the same time, the conductive filaments were gradually fused due to the continuous external electric field. As a result, the performance of QLED devices continuously deteriorated.