Recent Progress of Large-Area Perovskite Thick Films for Direct X-ray Detection and Imaging

Halide perovskite materials have drawn great attention in direct X-ray detection due to their large atomic number and outstanding optoelectronic properties in the targeted energy ranges of 40–150 kVp for medical imaging, medical diagnostics, security screening, etc. Compared to single crystals, polycrystalline thick films possess the merits of substrate integration, large area, and controlled thickness, making them more ideal for flat-panel X-ray detection and imaging. The past several years have witnessed the fast development of the preparation of large-area perovskite films and imaging exploration on commercial thin-film transistor (TFT) backplanes. However, challenges still exist, such as pinholes or cracks during film preparation, inhomogeneous contact between perovskite films and commercial backplanes, and ion migration. In this case, a review of recent progress in large-area perovskite thick films would advance perovskite X-ray detection and imaging. In this review, we focused on the recent progress in the preparation of large-area perovskite thick films and their imaging applications. First, many representative works on the fabrication methods of large-area perovskite thick films were systematically reviewed, where the advantages and disadvantages of each typical synthesis method were critically presented, including mechanical sintering, doctor-blading, spray coating, ultrasound-assisted crystallization, and polycrystal-induced growth. Subsequently, bottlenecks and prospects in the development directions based on perovskite X-ray detection for imaging applications are proposed.