Zero-Dimensional Organic–Inorganic Copper(I) Bromide for White Light-Emitting Diode Applications with an Ultrahigh Color Rendering Index

Hybrid cuprous halides demonstrate a high photoluminescence quantum yield and rich structural dimensionality, acting as promising candidates for the next generation of luminescent materials in the solid-state lighting field. However, the development of highly efficient orange-red light emitters with broadband emission remains a challenge. Herein, we report a zero-dimensional (0D) copper(I) halide, (HTPP)2Cu4Br6 (HTPP+= hexyl(triphenyl)phosphonium cation), where the isolated [Cu4Br6]2– units are wrapped by organic HTPP+ cations. (HTPP)2Cu4Br6 displays an orange-red emission band that peaks at 666 nm and possesses a relatively large Stokes shift of 294 nm, along with a broadband emission covering the wavelength range of 400–900 nm. The luminescence mechanism was thoroughly investigated with first-principles calculations. Significantly, based on this material, a white light-emitting diode (WLED) was fabricated with an ultrahigh color rendering index of 95.3. Moreover, the color rendering index maintained an average value of 94.5 over the 8 h continuous operation period of the WLED device. This work provides an important reference for the development of highly efficient copper(I) halides in solid-state lighting.