Optical and Device Architecture Engineering for High-Performance White Perovskite Light-emitting Devices

Description

Metal halide perovskite light-emitting diodes (PeLEDs) are a promising new-generation lighting technology with excellent optoelectronic properties and compatibility with lowcost solution processes. Over the past few years, PeLED efficiency has substantially improved, reaching external quantum efficiencies (EQEs) exceeding 20% for red and green PeLEDs and 12% for blue PeLEDs [1–3]. However, realising the potential of white PeLEDs (WPeLEDs) for solid-state lighting application represents a majorchallenge in this field, as an advanced LED design is needed to integrate different emission colours to generate white light. Although several reports have demonstrated the feasibility of constructing WPeLEDs using mixed perovskite phases [4], lanthanidemetal doping [5 ], down-conversion methods [6] and tandem structures [7], WPeLED efficiency is unsatisfactory, lagging behind those of single-colour-emitting PeLEDs. Therefore, it is imperative to exploit new strategies to realise high-performance tricolourWPeLEDs. In this project, we aim to develop high-performance tri-colour WPeLEDs with excellent EQEs, good colour-rendering properties and optimal operation stability, leading the evolution of WPeLEDs. To achieve white light emission, we propose a novel devicearchitecture design that couples electroluminescence (EL) and down-conversion photoluminescence (PL) with complementary colours, i.e., an edge-cutting top-emissive PeLED structure consisting of a bottom blue PeLED driving cell and upper green andred perovskite layer down-converters. The top-emissive design will improve LED light extraction efficiency (LEE) by suppressing optical losses resulting from photon trappin in the glass substrate. An ultra-thin top transparent electrode will be introduced tooptically couple the blue PeLED and the down-conversion layers, further reducing optical losses. The successful implementation of this proposed project will have far-reaching impacts for the development of high-efficiency and stable WPeLEDs, facilitating commercialisation. The optical design for improving LEE in this proposal is applicable tomost LED materials and devices.