Crystal growth and scintillation properties of pure and Tl-doped Cs₃Cu₂I₅

In this work the Bridgman crystal growth and scintillation properties of both undoped and Tl-doped Cs3Cu2I5 are presented. This material is very attractive for gamma and X-ray detection applications, with a density of 4.53 g/cm(3) and effective atomic number of 51.9. Undoped Cs3Cu2I5 had a light yield of 41,500 photons/MeV, with an energy resolution of 4.4% at 662 keV. Thallium doping at 0.5 mol % resulted in a much-improved scintillation response, in which light yield increased to 98,200 photons/MeV and energy resolution reduced to 3.3% at 662 keV. The X-ray excited emission is centered at 442 nm for the undoped and 500 nm for the Tl-doped crystals. The undoped emission is broad, typical of excitonic emission, while thallium doping results in an even broader band with features of both the undoped and thallium defect-mediated emissions.