Ultra‐stable and Sensitive X‐ray Detectors Using 3D Hybrid Perovskitoid Single Crystals

Abstract Organic–inorganic hybrid perovskites (OIHPs) have shown great potential for direct X‐ray detection in security screening and medical diagnostics. However, their humidity stability is compromised due to the susceptibility of the structural components to water molecules, thereby limiting their practical application. In this work, stable and sensitive X‐ray detection is achieved using high‐quality bulk single crystals of the 3D perovskitoid (DMPZ)Pb ₂ Br ₆ ( DPB , DMPZ = N , N ′‐dimethyl‐pyrazinium), wherein N ‐acid protons are replaced with hydrophobic alkyl groups. Notably, the crystals maintain phase stability after 60 days of immersion in water at room temperature, demonstrating their significant potential for moisture‐stable X‐ray detectors. Based on the bulk crystals of DPB , the X‐ray detectors are successfully fabricated, achieving a high sensitivity of 6437.2 µC Gy _air ⁻¹ cm ⁻² at 70 V bias and a detection limit low to 46.7 nGy _air s ⁻¹ , outperforming most low‐dimensional perovskite detectors. Most strikingly, the detectors retain 79.6% of their initial sensitivity after 14 days of water immersion, highlighting exceptional moisture stability. This work is the first to construct moisture‐stable high‐performance X‐ray detectors using 3D perovskitoid single crystals, advancing the development of stable X‐ray detection.