Exploring performance degradation of quantum-dot light-emitting diodes

Abstract

The indistinct mechanism of operational instability still suppresses the application and development of quantum-dot (QD) light-emitting diodes (QLEDs). Here, we construct an in situ electrical and optical monitoring system to clarify the mechanism of the performance degradation of QLEDs. The results reveal that the electrons leaked from the QD emissive layer continuously get injected into the organic hole transport layer (HTL), resulting in the reduction reaction of the HTL, which increases inter-band defects. This reduces obviously the hole mobility of the HTL and further aggravates the unbalanced injection of electrons and holes within QLEDs. We insert an electron blocking layer between the QD emissive layer and the electron transport layer to alleviate the effect of electron leakage on the HTL, thus improving the efficiency (>21%) and operational stability (T₉₅ of 3000 h@1000 cd m⁻²), which verifies the reliability of our proposed mechanism of performance degradation of QLEDs.