The role of excitons within the hole transporting layer in quantum dot light emitting device degradation

Abstract

This work investigates the root causes of the limited stability of electroluminescent quantum dot light-emitting devices (QDLEDs). Studies using electrical measurements, continuous UV irradiation, and both steady-state and transient photoluminescence (PL) spectroscopy reveal that exciton-induced degradation of the hole transporting material (HTM) in QDLEDs plays a role in limiting their electroluminescence (EL) stability. The results indicate that there is a correlation between device EL stability and the susceptibility of the HTM to exciton-induced degradation. The presence of quenchers in the HTM layer can lead to a decrease in the luminescence quantum yield of QDs, suggesting that energy transfer between the QD and HTM films may play a role in this behavior. The results uncover a new degradation mechanism where excitons within the HTM limit the EL stability of QDLEDs.