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 (MAPbX 3, 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 Δ E q from 53 ± 3 to 6 ± 1 meV. We replace MA in MAPbBr 3 with Cs and observe that the quenching temperature even shifts to lower temperature. But unlike the MAPbX 3 perovskites, the quenching in CsPbBr 3 is now affected by the increase of the ratio between the thermal quenching rate and the radiative transition rate (Γ 0 /Γ v ) from 15 ± 1 to 66 ± 14. The same influence was observed if we dope MAPbBr 3 with Bi 3+, Γ 0 /Γ v 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.