P‐5.1: Enhanced Nickel Oxide Hole Injection Layer via the rGO Combustion Method for Perovskite QDs Light‐Emitting Diodes

Abstract

Nonstoichiometry nickel oxide (NiOx) hole injection layer (HIL) plays an important role in realizing highly efficient and stable perovskite quantum dot light‐emitting diodes (QLEDs). Here, we report the use of solution processed rGO‐doped NiOx thin films as the hole injection layer (HIL) in the perovskite CsPbBr3 QLEDs, with an emphasis on the significantly improved device efficiency. The device (Figure. 1a) consists of multiple layers arranged in the following order: FTO/rGO: NiOx/TFB/CsPbBr3/TPBi/LiF/Al. As shown in Figure. 2, compared to un‐doped NiOx based QLEDs, higher luminance and luminous efficiency are achieved from the rGO: NiOx device. The enhanced efficiency of the QLED can be attributed to the reduced defective oxygen and enhanced hole injection ability of the rGO: NiOx layer. It is found that during the thermal annealing step, the rGO helps reduce the defective oxygen (e.g., OH‐ group) in the nonstoichiometric thin film and improve the hole extraction efficiency. Figure. 2c shows maximum luminance and external quantum efficiency (EQE) of 1009 cd/m2 and 0.19%, which are 68.2% and 51.9% higher compared to the un‐doped NiOx based QLEDs.