Efficient Large‐Area (81 cm²) Ternary Copper Halides Light‐Emitting Diodes with External Quantum Efficiency Exceeding 13% via Host‐Guest Strategy

Abstract

Ternary copper (Cu) halides are promising candidates for replacing toxic lead halides in the field of perovskite light‐emitting diodes (LEDs) toward practical applications. However, the electroluminescent performance of Cu halide‐based LEDs remains a great challenge due to the presence of serious nonradiative recombination and inefficient charge transport in Cu halide emitters. Here, we report the rational design of host‐guest [dppb]2Cu2I2 (dppb denotes 1,2‐bis[diphenylphosphino]benzene) emitters and its utility in fabricating efficient Cu halide‐based green LEDs that show a high external quantum efficiency (EQE) of 13.39%. The host‐guest [dppb]2Cu2I2 emitters with mCP (1,3‐Bis(N‐carbazolyl)benzene) host demonstrate a significant improvement of carrier radiative recombination efficiency, with the photoluminescence quantum yield increased by nearly 10 times, which is rooted in the efficient energy transfer and type‐I energy level alignment between [dppb]2Cu2I2 and mCP. Moreover, the charge‐transporting mCP host can rise the carrier mobility of [dppb]2Cu2I2 films, thereby enhancing the charge transport and recombination. More importantly, this strategy enables a large‐area prototype LED with a record‐breaking area up to 81 cm2, along with a decent EQE of 10.02% and uniform luminance. We believe these results represent an encouraging stepping stone to bring Cu halide‐based LEDs from the laboratory towards to commercial lighting and displays panels.This article is protected by copyright. All rights reserved