Lead-free halide perovskite Cs 3 Bi 2 Br 9 single crystals for high-performance X-ray detection

All-inorganic lead-free halide perovskites have attracted interest owing to their high ambient and thermal stabilities, excellent optoelectronic properties, and environmental friendliness. Herein, the bismuth-based halide perovskite Cs3Bi2Br9 single crystals were successfully grown to a diameter of 12 mm and length of 40 mm using a modified Bridgman method for the first time. The resistivity and transmittance of transparent and crack-free Cs3Bi2Br9 single crystal are ~6.8×1011 Ω cm and ~80%, respectively. The carrier mobility of the (−120) plane is 0.17 cm2 V−1 s−1 along the [010] orientation (b axis), and the trap density is 9.7×1010 cm−3. Moreover, Cs3Bi2Br9 single crystals exhibit excellent potential for X-ray detection, including a high absorption coefficient, a superior X-ray sensitivity of ~230.4 µC Gyair−1 cm−2, and an ultra-low and no-drift dark current density of ~17.8 pA mm−2, which enables lower noise and is also beneficial to the ultra-low detection limit for X-ray detectors. Our study shows that Cs3Bi2Br9 is a promising candidate for X-ray detection applications.