Te4+-Doped Zero-Dimensional Cs2ZnCl4 Single Crystals for Broadband Yellow Light Emission

As an all-inorganic 0D lead-free metal halide, Cs2ZnCl4 is a potential excellent matrix to prepare chemical stable and environmentally friendly photoluminescent materials through ion doping strategy. So, it is necessary to study the emission property of every kind of doping ion in the tetrahedral coordination of Cs2ZnCl4 actually. Here, for the first time, we successfully synthesize the Te4+-doped Cs2ZnCl4 single crystals via a facile hydrothermal method. X-ray crystallography clearly reveals the strong distortion of the tetrahedral units in Cs2ZnCl4 caused by the doping of Te4+. Broadband yellow-light emission covering from 450 nm to 700 nm with a large Stokes shift is observed in Cs2ZnCl4:Te4+ single crystals and attributed to the self-trapped excitons (STEs) caused by the lattice vibration of the distorted structure. It is worth mentioning that this broadband yellow phosphor can be excited by a wide range of blue light, implicitly giving it excellent talent to adapt to multiple models of blue LED chips, thus serving as suitable yellow phosphor that can be applied to fabricate WLEDs without need to worry about the lack of red light.