CsPbIBr₂ Thick Film With (100)‐Preferred Orientation Enables Highly Sensitive X‐Ray Detector by a Spray‐Coating Method via Dual‐Additive‐Assisted Solution Strategy under Atmospheric Environment

Abstract The realization of large‐area high‐quality perovskite thick films under an atmospheric environment without humidity control is confronting an urgent challenge for the applications in X‐ray detection and imaging. A spray‐coating method with air as the gas carrier is employed to achieve large‐area perovskite thick films for X‐ray flat‐panel detection applications. To further improve the quality of the thick films, the 10 µm‐thick CsPbIBr 2 films with (100)‐preferred orientation, low trap density (7.1 × 10 12 cm −3 ) and high resistivity corresponding to low dark current (3.2 × 10 −9 A) are prepared via dual‐additive‐assisted (NH 4 SCN and L‐α‐phosphatidylcholine (LP)) solution strategy under atmospheric environment with relative humidity of 60% (60% RH). Thus, the metal‐semiconductor‐metal‐structured (Au/CsPbIBr 2 /Au) transverse X‐ray detection device under 40 KeV X‐ray irradiation possesses a high sensitivity up to 1420 µC Gy air −1 cm −2 under a weak electric field of 18 V mm −1 and a low dose rate of 3.3 µGy air s −1 that is lower than a dose rate of ≈5.5 µGy air s −1 required for routine medical diagnosis. Strikingly, the unencapsulated device maintains 80% (1120 µC Gy air −1 cm −2 ) of the original sensitivity after 1000 h under the atmospheric environment with 45–55% RH. These results pave the way for the practical applications of perovskite thick films in X‐ray medical detection and imaging.