Halogen-Engineered Copper-Based Materials with Multicolor Emission for Dual-Functional Anticounterfeiting and LED Applications

Two novel zero-dimensional Cu-based halides (C6H7ClN)4Cu2X6 (X = Cl, Br) with excellent emission performances were successfully synthesized by a simple solution method. The hydrogen bonds and distortions of [Cu2X6]4– clusters make (C6H7ClN)4Cu2Cl6 and (C6H7ClN)4Cu2Br6 crystallize in monoclinic P21/c and triclinic P1, respectively. Interestingly, attributed to STE mechanisms, (C6H7ClN)4Cu2Cl6 and (C6H7ClN)4Cu2Br6 display broadband green-yellow and green emissions, large Stokes shifts, broad fwhms, and long lifetimes of the microsecond level. Notably, the PLQY was enhanced from 59.68 to 71.15% by halogen regulation with Br– being utilized to replace Cl–. Furthermore, first-principles calculations were performed to investigate the relationship of structure–performance. Moreover, based on the bright emissions and different emitting colors of (C6H7ClN)4Cu2Cl6 and (C6H7ClN)4Cu2Br6, multiple anticounterfeiting methods and LED devices in solid-state illumination were designed to explore underlying optoelectronics applications. This work not only provides two novel low-dimensional copper halides with excellent photoluminescence but also promotes practical applications in information security and solid state lighting.