Sunlike Full‐Spectrum White Light‐Emitting Diodes Based on Efficient and Eco‐Friendly Hybrid Copper Halide Ionic Crystals

ABSTRACT White light‐emitting diodes are regarded as a substitute for traditional incandescent lights, becoming promising solid‐state light sources. However, the insufficiency of rare earth elements, environmental problems caused by element mining, and an inadequate color rendering index for high‐saturation colors restrict long‐term application. Herein, a kind of sunlike full‐spectrum white light‐emitting diodes is successfully prepared, consisting of two complementary‐color low‐toxicity copper‐based materials, which demonstrates an excellent color rendering index. Two types of eco‐friendly hybrid copper halide ionic crystals with broadband emission are synthesized via cooling crystallization, exhibiting near unity photoluminescence quantum yields. Different thermal‐assisted self‐trapped exciton emission mechanisms result in distinctive temperature‐dependent photoluminescence, both of which possess robust resistance against thermal quenching and good stability under UV laser irradiation. The white light‐emitting diode devices were fabricated with an appropriate ratio of two kinds of phosphors, which show splendid rendering index, R a of 93, and R 9 of 86 simultaneously, and operational half‐lifetime of 140 h under a continuous 250 mA current mode. The results provide an approach for achieving healthy lighting using environmentally friendly materials.