Amine-Terminated Carbon Dots Linking Hole Transport Layer and Vertically Oriented Quasi-2D Perovskites through Hydrogen Bonds Enable Efficient LEDs
Wei Dong, Xiaoyu Zhang, Fan Yang, Qingsen Zeng, Wenxu Yin, Wei Zhang, Haoran Wang, Xuyong Yang, Stephen V. Kershaw, Yang Bai, Andrey L. Rogach, Weitao Zheng
Abstract
Close attention to the interfaces of solution-processed metal halide perovskite-based light-emitting devices (LEDs) is crucial for their optimal performance. Solution processing of these devices typically leads to the formation of van der Waals interfaces with a weak connection between different functional layers, leaving great room for improvement in charge transport through strengthening of the interlayer interaction. Here, we have realized a hydrogen-bond-assisted interface that makes use of ultrasmall amine-terminated carbon dots to enhance the interaction between the hole transport layer made of PEDOT:PSS and the hybrid lead bromide perovskite emitting layer, which not only promotes the hole injection efficiency but also orients the quasi-2D perovskite crystals penetrating the vertical direction of the device without any, or very few, horizontal grain boundaries, which has a profound effect on the photophysical and transport properties of the emitting layer. As a result, LEDs based on quasi-2D perovskites show up to 24.5% external quantum efficiency, 80 000 cd m–2 brightness, and over 5-fold extended longevity.