Identifying Carrier Behavior in Ultrathin Indirect-Bandgap CsPbX3Nanocrystal Films for Use in UV/Visible-Blind High-Energy Detectors

High-energy radiation detectors such as X-ray detectors with low light photoresponse characteristics are used for several applications including, space, medical, and military devices. Here, an indirect bandgap inorganic perovskite-based X-ray detector is reported. The indirect bandgap nature of perovskite materials is revealed through optical characterizations, time-resolved photoluminescence (TRPL), and theoretical simulations, demonstrating that the differences in temperature-dependent carrier lifetime related to CsPbX3(X = Br, I) perovskite composition are due to the changes in the bandgap structure. TRPL, theoretical analyses, and X-ray radiation measurements reveal that the high response of the UV/visible-blind yellow-phase CsPbI(3)under high-energy X-ray exposure is attributed to the nature of the indirect bandgap structure of CsPbX3. The yellow-phase CsPbI3-based X-ray detector achieves a relatively high sensitivity of 83.6 mu CGy(air)(-1)cm(-2)(under 1.7 mGy(air)s(-1)at an electron field of 0.17 V mu m(-1)used for medical diagnostics) although the active layer is based solely on an ultrathin (approximate to 6.6 mu m) CsPbI(3)nanocrystal film, exceeding the values obtained for commercial X-ray detectors, and further confirming good material quality. This CsPbX3X-ray detector is sufficient for cost-effective device miniaturization based on a simple design.