Thermal Quenching and Dose Studies of X‑ray Luminescence in Single Crystals of Halide Perovskites

Temperature- and dose-dependent measurements of X-ray luminescence (XL) in various perovskite single crystals are reported. For methylammonium lead halide perovskites (MAPbX3, MA = methylammonium, X = Cl, Br, or I), the quenching temperature of XL intensities shifts to lower temperatures in the sequence from Cl to I. This quenching is strongly affected by the decrease of the thermal activation energy ΔE q from 53 ± 3 to 6 ± 1 meV. We replace MA in MAPbBr3 with Cs and observe that the quenching temperature even shifts to lower temperature. But unlike the MAPbX3 perovskites, the quenching in CsPbBr3 is now affected by the increase of the ratio between the thermal quenching rate and the radiative transition rate (Γ0/Γv) from 15 ± 1 to 66 ± 14. The same influence was observed if we dope MAPbBr3 with Bi3+, Γ0/Γv increases to 78 ± 18 for crystal with Bi/Pb ratio of 1:10 in precursor solution. For larger dose of X-ray, we observe that the XL intensities are still linear without saturation. Unlike temperature-dependent measurements, we do not observe the line width narrowing in dose-dependent XL spectra. Thus, this scintillator is still stable with the large X-ray dose in comparison with the variation in the temperature.