Zero-Dimensional Cs ₂ TeI ₆ Perovskite: Solution-Processed Thick Films with High X-ray Sensitivity

We demonstrate a potential candidate, the 0D "all-inorganic" perovskite material Cs ₂ TeI ₆ , as a sensitive all-inorganic X-ray photoconductor for the development of the new generation of direct photon-to-current conversion flat-panel X-ray imagers. Cs ₂ TeI ₆ consists of high atomic number elements, has high electrical resistance, and exhibits high air and moisture stability, making it suitable as a sensitive X-ray photoconductor. In addition, we identify that Cs ₂ TeI ₆ film can be prepared under a low-temperature process using electrostatic-assisted spray technique under atmospheric conditions and achieved resistivity of 4.2 × 10 ¹⁰ ω·cm. The resulting air- and water-stable Cs ₂ TeI ₆ device exhibits a strong photoresponse to X-ray radiation. An electron drift length on the order of 200 μm is estimated under an applied electrical field strength of 400 V·cm ^-1 . A high sensitivity for Cs ₂ TeI ₆ thick film device is realized, with the value of 192 nC·R ^-1 cm ^-2 under 40 kVp X-rays at an electrical field of 250 V·cm ^-1 , which is ∼20 times higher than that of the hybrid 3D perovskite polycrystalline film X-ray detectors. X-ray imaging based on Cs ₂ TeI ₆ perovskite films will require lower radiation doses in many medical and security check applications.