Tuning the Photon Sensitization Mechanism in Metal‐Halide‐Perovskite‐Based Nanocomposite Films Toward Highly Efficient and Stable X‐Ray Detection

Metal halide perovskites (MHPs) have emerged as promising X‐ray detection materials. However, most MHP‐based X‐ray detectors are incompatible for large‐area preparation and integration, and suffer from the serious ion migration issue. This work demonstrates a “perovskite‐in‐a‐host” nanocomposite structure for X‐ray detection, by embedding the perovskite nanocrystal (PNC) sensitizers in the organic interpenetrating charge transport channels to work as the X‐ray attenuation layer. Intriguingly, the photon sensitization mechanism can be readily tuned from indirect‐ to direct‐type X‐ray conversion by decreasing the ligand density on the PNC surface, which significantly increases the sensitivity to 5 696 µC Gyair–1 cm–2. Besides, the ion migration gets suppressed due to the ion blocking effect of the surrounding organic phase. Therefore, an ultra‐small dark current relative drift of 3.57 × 10–9 cm s–1 V–1 is achieved even under an extremely large electric field up to 5 100 V cm–1, ensuring a low detection limit down to 72 nGyair s–1. The superior sensitivity and biasing stability enable the high performance X‐ray imaging capability of the devices, which exhibit great potential in scaling up and integration for the flat panel imaging. A “perovskite‐in‐a‐host” nanocomposite structure is prepared for X‐ray detection by embedding the perovskite nanocrystal (PNC) sensitizers in the organic interpenetrating charge transport channels to work as the X‐ray attenuation layer. The photon sensitization mechanism is modulated by regulating the ligand density on the PNCs, which enables a highly sensitive and stable X‐ray detection performance.