Time-Resolved Mechanism\nof Positive Aging in InP Quantum-Dot\nLight-Emitting Diodes

Positive aging has been reported to be effective for\nenhancing\nelectroluminescence characteristics of quantum dot (QD) based optoelectrical\ndevices. This study investigated the intricate mechanisms underlying\nthe positive aging effect in quantum-dot light-emitting diodes (QLEDs)\ninfluenced by encapsulation with ultraviolet-curable resin. A 120-h\nanalysis assessed the impact of the resin on the electron transport\nlayer and emission layer, utilizing a strategically positioned perfluorinated\nionomer (PFI) interlayer. The PFI layer effectively delayed the Al<sub>2</sub>O<sub>3</sub> formation at the zinc magnesium oxide (ZMO)/Al\ninterface and further reduced the interactions within the QD/ZMO interface,\nthereby curtailing exciton quenching at the interfaces. The time-sequential\neffect of positive aging demonstrated that resin encapsulation effectively\npassivates the ZMO surfaces after 12 h. The positive aging facilitated\nthe reaction between aluminum and oxygen from ZMO, contributing to\nAl<sub>2</sub>O<sub>3</sub> formation within 48 h of aging. Furthermore,\npositive aging passivated the defect states of the QD surface and\nthe QD/ZMO interface, reducing exciton quenching at the QD or QD/ZMO\ninterface. The enhanced electron injection and reduced exciton quenching\nresulted in aged InP QLEDs, exhibiting an external quantum efficiency\nof 12.04%. This is a significant increase from the 3.16% observed\nin the control device. Finally, a sequential mechanism of positive\naging in InP QLEDs was devised, providing new insights into the time-related\noperation of aging agents. This study elucidates an advanced time-resolved\nmechanism of positive aging, thereby offering valuable insights into\nthe intricate dynamics of excitons within the domain of QLED physics.