High Brightness Electroluminescence of Non‐Carrier‐Injection QLEDs with Precise Layer Processing by Spontaneous Spreading Method

Abstract

AbstractThe luminescent properties and mechanisms of non‐carrier injection (NCI) mode quantum dot light‐emitting diodes (QLEDs) are explored in this work. The intermediate insulator electric layer, Poly(vinylidene fluoride‐trifluoroethylene‐chlorofluoroethylene) (P(VDF‐TrFE‐CFE)), effectively blocks carrier injection from the electrodes. Carriers for radiative recombination in the quantum dot (QD) layer are generated by the corresponding carrier generation complex layer under an AC electric field. In this investigation, the emission layer (EML), comprising distinct layers of Cd‐based quantum dots, is precisely regulated using the spontaneous spreading (SS) method. The work reveals that the thickness of the QDs in NCI‐QLEDs significantly influences the device's luminescent performance. In NCI‐QLEDs with a double QD layer as the EML, the device exhibits a maximum brightness of 1003.6 cd m⁻2 and a start‐up voltage of 7 root mean square voltage (VRMS). This brightness level represents the highest reported for vertical emission NCI‐QLEDs. All devices exhibit a broad range of driven voltages. Interestingly, luminescence is detected only during a half‐cycle of the driven signal, as indicated by transient time‐resolved spectrum test results. A system is established to analyze the luminescence mechanism comprehensively. Finally, a proposed carrier compounding mechanism sheds light on the behavior of NCI‐QLED devices.