Solution-Grown Hypervalent CsI₃ Crystal for High-Sensitive X-Ray Detection

Herein, a novel binary compound hypervalent CsI₃ crystal is designed for X-ray detection. Solution-grown rod-like CsI₃ single crystal is identified as a semiconductor with a bandgap of 1.79 eV and high resistivity of 2.17 × 10⁹ Ω cm, which make it suitable for X-ray detection. Based on carbon/CsI₃ crystal/carbon device, a high X-ray sensitivity of up to 158.1 ± 6.0 μC Gy⁻¹ cm⁻² is achieved under a low electrical field of 55 V mm⁻¹, which is eight times higher than that of the commercial α-Se X-ray detectors. The high sensitivity of hypervalent CsI₃ is attributed to the long carrier life time (≈470 μs) and large photocurrent gain (150%). The potential applications of photoconversion and nuclear radiation detection using alkali halides are demonstrated.