Low‑Temperature Quasi‑Static Seeded Columnar Grain Growth of Thick Perovskite Films with Minimal Stress for Sensitive X‑ray Detection

Abstract

The large difference in thermal expansion coefficients between lead halide perovskites and the substrate resulting in delamination during thermal anneal process, which hinder the application of thick perovskite film-based X-ray detector. To mitigate interfacial thermal stress and film cracking in perovskite thick films, we developed a quasi-static epitaxial blade-coating method by utilizing the saturated precursor solution induced crystal growth under low temperature. By employing the highly volatile solvent 2-methoxyethanol in an air-assisted coating process, an orderly, slow epitaxial growth of perovskite thick film on a seed layer at only 40 °C has been obtained. This nearequilibrium growth minimizes internal stress, resulting in MAPbI 3 films with large columnar grains, low pinhole density, and strong substrate adhesion without cracking.The assembled X-ray detector exhibits a high sensitivity of 2891.8 μC Gy air -1 cm -2 at 2.5 V under 40 kV irradiation. This work provides a scalable, low-temperature route to control the stress between perovskite thick films and the substrate for high-performance radiation detection.