Direct Ink Writing of Single‐Crystal‐Assembled Perovskite Thick Films for High‐Performance X‐ray Flat‐Panel Detectors

Abstract Halide perovskites hold great potential in developing next‐generation X‐ray detectors. However, preparing high‐quality and thick perovskite films in a way compatible with a thin‐film transistor (TFT)‐integrated X‐ray flat‐panel detectors (XFPDs) remains challenging. Here, by engineering ink with effective printability and shape fidelity, direct ink writing (DIW) is developed as a new approach to printing a unique single‐crystal‐assembled perovskite (SCAP) thick film. In contrast to polycrystalline grains consisting of randomly orientated crystal domains, the SCAP is made of tightly packed crystals with well‐defined crystal facets, showing 3–4 orders of magnitude lower trap density (4.48 × 10 12 cm −3 ). Consequently, the SCAP X‐ray detectors offers the state‐of‐the‐art detection performance (sensitivity‐to‐dark current ratio: 1.26 × 10 11 µC Gy air −1 A −1 ), a low detection limit (114.2 nGy air s −1 ), and negligible baseline drift (0.27 fA cm −1 s −1 V −1 ). Furthermore, the XFPD based on a 64 × 64 pixelated TFT array realizes high‐resolution digital radiography, opening a new avenue for further development of perovskite X‐ray detectors.