Interface Engineering of Substrate‐Integrated Single‐Crystal Perovskite Wafers for Sensitive X‐Ray Detection

Abstract Metal halide perovskite single crystals are emerging candidates for X‐ray detection, however, it is challenging for growth of thickness‐controlled single‐crystal wafer on commercial backplanes, limiting their practical imaging application. Herein, integration of micrometer‐thick methylammonium lead triiodide (MAPbI 3 ) single‐crystal wafer on indium tin oxide (ITO) substrates by methylamine (MA)‐induced interface recrystallization is reported. Through selection of hole transport material with rich functional group, intimate interface contact with low trap density can be achieved, leading to superior carrier transport properties and homogeneous photoresponse. The as‐fabricated X‐ray detectors exhibit high sensitivity of 1.4 × 10 4 µC Gy air −1 cm −2 and low detection limit of 177 nGy air s −1 , which are comparable to previous reports based on free‐standing MAPbI 3 bulk crystals. This work provides a feasible strategy for constructing substrate‐integrated single‐crystal perovskite wafers with controlled thickness, which may promote practical imaging application of perovskite X‐ray detectors.