TISn2I5, a Robust Halide Antiperovskite Semiconductor for γ-Ray Detection at Room Temperature

The semiconductor TISn2I5 with a two-dimensional crystal structure and an antiperovskite topology is a promising novel detection material. The compound crystallizes in the 1.4/mcm space group, has an indirect band gap of 2.14 eV, and melts congruently at 314 degrees C. Electronic band structure calculations reveal that the most facile electron transport is along the ab layered plane. Compared to CH3NH3PbX3 (X = Br, I), TISn2I5 features higher long-term stability, higher photon stopping power (average atomic number of 55), higher resistivity (similar to 10(10) Omega.cm), and robust mechanical properties. Centimeter-size TISn(2)l(5) single crystals grown from the melt by the Bridgman method can be used to fabricate detector devices, which detect Ag K alpha X-rays (22 keV), Co-57 gamma-rays (122 keV), and Am-241 alpha-particles (5.5 MeV). The mobility-lifetime product and mobility for electrons were estimated to be 1.1 X 10(-3) cm(2).V-1 and 94 +/- 16 cm(2).V(-1)s(-1), respectively. Unlike other halide perovskites, TISn2I5 shows no signs of ionic polarization under longterm, high-voltage bias.