Ultra Broad‐Band Excitable Organic–Inorganic Copper(I) Halides: Large‐Scale Synthesis, Outstanding Stability, and Highly Efficient White Light‐Emitting Diodes Application

Abstract Organic–inorganic copper(I) halides (OICHs) have recently attracted great attentions for their unique optoelectronic properties. However, most of them have poor stability and narrow excitation in UV region, which seriously hinder their applications in efficient white light‐emitting diodes (WLEDs). Herein, 0D (C19H18P)2Cu4I6 with super broad‐band excitation (300–500 nm) and yellow emission with the absolute photoluminescence quantum yield of 87.4% is synthesized in a quantity of gram scale. Specifically, (C19H18P)2Cu4I6 possesses exceptional thermal‐, photo‐, air‐stability, and can maintain efficient emission even if soaked in water, ethyl acetate, and isopropanol over 30 days. WLEDs with remarkable color stability under various driven currents are fabricated using 450, 400, 365, and 310 nm LED chips. The ideal WLEDs based on single (C19H18P)2Cu4I6 by 450 nm LED chip presents high color rendering index of 86.7, and outstanding luminous efficiency of 90 lm W−1. To the best of the knowledge, this is the highest value that is achieved based on single‐component OICHs using blue light chip. This work not only promotes the prospect of OICHs in WLEDs but also significantly broadens their application in special lighting fields, such as underwater illumination.