Efficient metal halide perovskite light-emitting diodes with significantly improved light extraction on nanophotonic substrates

Qianpeng Zhang,Siu-Fung Leung,Zhiyong Fan,Ji Guo,Mohammad Mahdi Tavakoli,Daquan Zhang,Yuan Gao,Swapnadeep Poddar,Leilei Gu,Yuanjing Lin,Lei Tang,Yu Fu

doi:10.1038/s41467-019-08561-y

Abstract

Metal halide perovskite has emerged as a promising material for light-emitting diodes. In the past, the performance of devices has been improved mainly by optimizing the active and charge injection layers. However, the large refractive index difference among different materials limits the overall light extraction. Herein, we fabricate efficient methylammonium lead bromide light-emitting diodes on nanophotonic substrates with an optimal device external quantum efficiency of 17.5% which is around twice of the record for the planar device based on this material system. Furthermore, optical modelling shows that a high light extraction efficiency of 73.6% can be achieved as a result of a two-step light extraction process involving nanodome light couplers and nanowire optical antennas on the nanophotonic substrate. These results suggest that utilization of nanophotonic structures can be an effective approach to achieve high performance perovskite light-emitting diodes.

Highlights

Metal halide perovskite has emerged as a promising material for light-emitting diodes
The alumina membranes (AAMs)(TiO2 NWs) layer is a photon management structure consisting of a hexagonal array of NDs as the barrier layer and a layer of TiO2 NW array embedded in AAM
Different materials were sequentially deposited on the AAM NDs barrier layer to form a light-emitting diodes (LEDs) device and the detailed process can be found in the Methods section

Summary

Introduction

Metal halide perovskite has emerged as a promising material for light-emitting diodes. Optical modelling shows that a high light extraction efficiency of 73.6% can be achieved as a result of a two-step light extraction process involving nanodome light couplers and nanowire optical antennas on the nanophotonic substrate These results suggest that utilization of nanophotonic structures can be an effective approach to achieve high performance perovskite light-emitting diodes. Note that for typical organic LEDs (OLEDs), the refractive index difference between the active materials and injection layer is typically not this large, light extraction efficiency is not a significant performance limiting factor. There are some works devoted to address the light extraction problems with microlens or hollow fiber structures and achieved a few times enhancement for OLED performance[21,22] This approach has not been adopted for metal halide Pero LEDs to our best knowledge. It is worth mentioning that the unique nanophotonic LED substrate demonstrated in this work can be used for other perovskite material systems to achieve high performance in the future

Methods

Results

Conclusion