  Current technologies for X-ray detection rely on scintillation from expensive
inorganic crystals grown at high-temperature, which so far has hindered the
development of large-area scintillator arrays. Thanks to the presence of heavy
atoms, solution-grown hybrid lead halide perovskite single crystals exhibit
short X-ray absorption length and excellent detection efficiency. Here we
compare X-ray scintillator characteristics of three-dimensional (3D) MAPbI3 and
MAPbBr3 and two-dimensional (2D) (EDBE)PbCl4 hybrid perovskite crystals. X-ray
excited thermoluminescence measurements indicate the absence of deep traps and
a very small density of shallow trap states, which lessens after-glow effects.
All perovskite single crystals exhibit high X-ray excited luminescence yields
of >120,000 photons/MeV at low temperature. Although thermal quenching is
significant at room temperature, the large exciton binding energy of 2D
(EDBE)PbCl4 significantly reduces thermal effects compared to 3D perovskites,
and moderate light yield of 9,000 photons/MeV can be achieved even at room
temperature. This highlights the potential of 2D metal halide perovskites for
large-area and low-cost scintillator devices for medical, security and
scientific applications.
