Fast fabrication of m-thick perovskite films by using a one-step doctor-blade coating method for direct X-ray detectors

Deposition of large-area perovskite films for direct X-ray detectors under ambient conditions is highly desirable for commercial application. In this work, we employ a one-step doctor-blade coating method to prepare a perovskite film with the advantages of rapid fabrication, easy scalability, and raw material savings. We incorporate a high content of 20-wt% crown ether, namely 18-crown ether-6 (18C6), into the perovskite precursor solution to prepare a mu m-thick perovskite film, which effectively attenuates the X-ray irradiation. The large cyclic structure of 18C6 bonding with the DMSO solvent and solutes via the hydrogen and van der Waals forces increases the viscosity of the precursor solution from 3.4 mPa s (0-wt% 18C6) to 41.3 mPa s (20-wt% 18C6). A continuous, compact, and uniform perovskite thick film with a thickness of 6.2 mu m is fabricated by the doctor-blade coating in just 10 seconds. The direct X-ray detectors based on the doctor-bladed perovskite thick film achieve a dark current density of 1.6 nA cm-2 under an electric field of 1/20 of that required for the commercial a-Se-based X-ray detector. The device sensitivity reaches 33.51 mu C Gyair-1 cm-2, and the limit of detection is determined to be 70.17 mu Gyair s-1. Our study paves a way toward industrialization with the merits of scalable, fast and easy production, and low-cost X-ray detectors. The inclusion of a high-content crown ether in the perovskite precursor effectively increases the thickness of the doctor-bladed perovskite film and enhances the X-ray photoresponse of the direct X-ray detector.