Temperature-dependent self-trapped exciton emission in Cu(I) doped zinc-based metal halides from well-resolved excited state structures

Zero-dimensional metal halides are of unique structures and tunable photoluminescence properties,showing great potential applications such as light-emitting diodes(LEDs)and sensing.Herein,we successfully synthesized Cu^(+)doped(MA)_(2)ZnCl_(4)metal halides by a slow evaporation solvent method.The introduction of Cu^(+)results in sky-blue self-trapped exciton emission in(MA)_(2)ZnCl_(4) at 486 nm at room temperature,and a photoluminescence quantum yield is as high as 54.9%.Interestingly,at low temperatures,Cu^(+)-doped(MA)_(2)ZnCl_(4) exhibits two emission peaks located at 482 and 605 nm,respectively.This temperaturedependent dual emission indicates two excited state structures that exist on the triplet excited-state potential energy surface.In addition,the temperature sensor we fitted has good performance(Sr=1.65%·K^(−1)),which is the first attempt in Cu^(+) doped Znbased metal halides.Our work enriches the family of sky-blue metal halides and provides a promising strategy for building skyblue LEDs.