Perspective: Toward highly stable electroluminescent quantum dot light-emitting devices in the visible range

Abstract

With significant improvements in external quantum efficiency (EQE) and stability for red, green, and blue devices over the past decade, the future of electroluminescent quantum dot light-emitting devices (QDLEDs) is bright. State-of-the-art QDLEDs have achieved >30% EQE and a >2 000 000 h electroluminescence half-life for an initial luminance of 100 cd m-2, rivaling those of organic light-emitting devices. To date, most of the improvements in QDLED performance have been primarily achieved via advancements in QD synthesis and design that aim at reducing Auger recombination and improving the balance between electron and hole concentrations in the emissive QD layer. However, recent work is starting to reveal the critical role that other device layers, as well as interlayer interfaces, play in limiting QDLED stability. Degradation within the organic hole transport layer (HTL) and near the QD/HTL interface has recently been found to lead to the formation of nonradiative recombination centers that quench excitons in the emissive QD layer and contribute to QDLED failure over time. Looking forward, minimizing degradation in the charge transport layers will likely be crucial for the realization of highly stable QDLEDs and this perspective provides potential avenues to achieve these enhancements. In particular, tailoring the QD energy levels via material selection or interfacial dipoles may reduce charge carrier accumulation in the transport layers and replacing the organic HTL with an inorganic alternative may be an effective approach to circumvent the inherent susceptibility of organic semiconductors to exciton-induced degradation.