High-Efficiency Eco-Friendly Deep-Blue ZnSeTe Quantum-Dots Light Emitting Diodes via Enhanced Hole Injection

Environmentally friendly blue ZnSeTe-based quantum dots light emitting diodes (QLEDs) are potential candidates for future high-definition displays. However, its development is usually hindered by the poor performance due to inefficient hole injection. Herein, we reported the hole injection reinforcement based on the intermolecular π-π interactions to construct high-performance blue ZnSeTe/ZnSe/ZnS QLEDs. It involves mixing a slight amount of poly(9-vinylcarbazole) (PVK) into ploy((9,9-dioctylfluorenyl-2,7-diyl)-alt-(9-(2-ethylhexyl)-carbazole-3,6-diyl)) (PF8Cz) as an efficient hole transport material (P-PF8Cz). P-PF8Cz achieves much deeper highest occupied molecular orbital energy level and much higher hole mobility than that of PF8Cz. This reduces the hole-injection barrier between hole-transport layer (HTL) and light-emitting layer, improving the hole injection and transport in the QLED. As a result, the P-PF8Cz HTL-based device achieves a peak external quantum efficiency of 12.74% (~37% improvement compared to the control sample of 9.27%) and a maximum luminance of 12,710 cd m-2.