Copper Mixed‐halide Hybrids with Intrinsic Broadband White‐Light Emission for WLED Application with Ultrahigh Color Rendering Index
Qianqian Wang, Haibo Li, Hua Tong, Jia‐Lin Zhu, Jiali Fan, Shifeng Pan, Zhennan Zhou, Wei Liu, Gangfeng Ouyang
Abstract
Abstract The development of single‐component white‐light emissive phosphors has become a key research area in white light‐emitting diode (WLED) technology. However, achieving real color reproduction with an ultrahigh color rendering index (CRI) remains challenging. Herein, a series of 0D hybrid copper halides (TEA) 2 Cu 2 Br 4‐ x Cl x (TEA = tetraethylammonium, x = 0–4) crystals are designed and prepared by a facile solvothermal method. By controlling the composition ratio of Cl − and Br − , the emission spectra are tunable in visible light region from blue to yellow, and a single‐component crystal (TEA) 2 Cu 2 Br 2 Cl 2 with broadband white‐light emission and ultrahigh CRI is obtained. Detailed studies on photophysical mechanism demonstrate that the unique 0D structure of (TEA) 2 Cu 2 Br 2 Cl 2 can produce effective emission of self‐trapped excitons (STEs), and its dual‐band emission phenomenon stems from two STE states in the [Cu 2 Br 2 Cl 2 ] 2− dimer. Moreover, the CIE coordinates of (TEA) 2 Cu 2 Br 2 Cl 2 (0.32, 0.33) are approximated to pure white light (0.33, 0.33), making it an ideal choice for natural WLED applications. A WLED device is fabricated by coating this emitter on a 310 nm UV chip, achieving an ultrahigh CRI of Ra = 95 and R9 = 90. This work provides new design principles for developing eco‐friendly white‐emission phosphors for single‐component solid‐state WLEDs.