Utilizing VO2 as a Hole Injection Layer for Efficient Charge Injection in Quantum Dot Light-Emitting Diodes Enables High Device Performance

Abstract

Quantum dot light-emitting diodes(QLEDs) are promising devicesfor display applications. Polyethylenedioxythiophene:polystyrene sulfonate(PEDOT:PSS) is a common hole injection layer (HIL) material in optoelectronicdevices because of its high conductivity and high work function. Nevertheless,PEDOT:PSS-based QLEDs have a high energy barrier for hole injection,which results in low device efficiency. Therefore, a new strategyis needed to improve the device efficiency. Herein, we have demonstrateda bilayer-HIL using VO2 and a PEDOT:PSS-based QLED thatexhibits an 18% external quantum efficiency (EQE), 78 cd/A currentefficiency (CE), and 25,771 cd/m(2) maximum luminance. Incontrast, the PEDOT:PSS-based QLED exhibits an EQE of 13%, CE of 54cd/A, and maximum luminance of 14,817 cd/m(2). An increasein EQE was attributed to a reduction in the energy barrier betweenindium tin oxide (ITO) and PEDOT:PSS, caused by the insertion of aVO(2) HIL. Therefore, our results could demonstrate thatusing a bilayer-HIL is effective in increasing the EQE in QLEDs.