Turning self-trapped exciton emission via Sb3+ doping in zero-dimensional hybrid indium chloride for X-ray scintillation

Zero-dimensional (0D) hybrid indium halides have recently received great attention for their potential as X-ray scintillators due to their non-toxicity, superior optical properties and exceptional stability. However, most indium halides suffer from low emission efficiency, resulting in inferior performance. Herein, we demonstrate that a small amount of Sb3+ doping can greatly enhance the photoluminescence efficiency of a 0D hybrid indium chloride, DMA4InCl7. The pristine crystals exhibit weak self-trapped exciton (STE) emission centered at 620 nm with a low quantum yield of 11%. After Sb3+ doping, the STE emission efficiency can be greatly increased to 91%. The spectroscopic experiments and theoretical calculations indicate the efficient energy transfer from excited Sb3+ ions to the emitting STE state of the host is responsible for the substantial increase in emission efficiency. Furthermore, we find the energy transfer efficiency is related to the distance between dopants and [InCl6]3- units. The strong STE emission endows the doped samples with desirable X-ray scintillation performance, with a high light yield of 23500 photons/MeV and a low detection limit of 175 nGyair·s−1.