Significant Enhancement in Quantum Dot Light-Emitting Device Stability via a Cascading Hole Transport Layer

This work investigates the effect of the hole transport layer (HTL) on the stability of electroluminescent quantum dot light-emitting devices (QDLEDs). The electroluminescence half-life (LT50) of QDLEDs can be improved by 25× through the utilization of a cascading HTL (CHTL) structure with consecutive steps in the highest occupied molecular orbital energy level. Using this approach, a LT50 of 864,000 h (for an initial luminance of 100 cd m^-2) is obtained for red QDLEDs using a conventional core/shell QD emitter. The CHTL primarily improves QDLED stability by shifting excessive hole accumulation away from the QD/HTL interface and toward the interlayer HTL/HTL interfaces. The wider electron-hole recombination zone in the CHTL for electrons that have leaked from the QD layer results in less HTL degradation at the QD/HTL interface. This work highlights the significant influence of the HTL on QDLED stability and represents the longest LT50 for a QDLED based on the conventional core/shell QD structure.