Mitigating Perovskite Light-Emitting Diode Degradation Mechanisms through Forward Electrical Pulses

The lifetime testing curve of perovskite quantum dot light-emitting diodes (Pe-QLEDs) reflects the complex interaction of various factors, including the inherent quantum dot (QD) leading to rapid decay and carrier injection imbalance issues. Mitigating these factors and understanding charge dynamics are crucial to enhance the stability and EQE of Pe-QLED devices. In this study, we first established a capacitance-voltage (C-V) model for Pe-QLEDs. We then analyzed the charge dynamics characteristics of four different regions in the typical C-V model, including the dark current region, low injection region, recombination region, and charge accumulation region. We revealed the quenching at the interface between CsPbI₃ QD and PO-T2T, as well as the injection imbalance issue. To address these issues, we designed a TmPyPB buffer layer with a shallow LUMO level at the interface between CsPbI₃ QD and PO-T2T to mitigate the defect increase caused by PO-T2T and enhance electron injection, thereby promoting charge balance. The C-V characteristic curves of the optimized Pe-QLED with the buffer layer confirmed the reduction of defects and the enhancement of radiative recombination. The optimized Pe-QLED exhibited a significant improvement in external quantum efficiency (EQE) from 11.66% to 19.57%. It demonstrated stable operation for T₅₇ = 1.56 h at 1000 nit after forward electrical pulses. Through C-V modeling and Nyquist plots, we quantitatively understood the charge dynamics processes in Pe-QLEDs, which provide clear directions for improving Pe-QLED EQE and stability.