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 CsPbIBr₂ films with (100)-preferred orientation, low trap density (7.1 × 10¹² cm⁻³) and high resistivity corresponding to low dark current (3.2 × 10⁻⁹ A) are prepared via dual-additive-assisted (NH₄SCN and L-α-phosphatidylcholine (LP)) solution strategy under atmospheric environment with relative humidity of 60% (60% RH). Thus, the metal-semiconductor-metal-structured (Au/CsPbIBr₂/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.