Zero-Dimensional Cs₂TeI₆ Perovskite: Solution-Processed Thick Films with High X‑ray Sensitivity

We demonstrate a potential candidate, the 0D “all-inorganic” perovskite material Cs₂TeI₆, 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. Cs₂TeI₆ 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 Cs₂TeI₆ film can be prepared under a low-temperature process using electrostatic-assisted spray technique under atmospheric conditions and achieved resistivity of 4.2 × 10¹⁰ Ω·cm. The resulting air- and water-stable Cs₂TeI₆ 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 Cs₂TeI₆ thick film device is realized, with the value of 192 nC·R^–1cm^–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 Cs₂TeI₆ perovskite films will require lower radiation doses in many medical and security check applications.