Polar Isomer‐Driven Cation‐Anion Coupling Enhances Carrier Dynamics and X‐Ray Detectors Sensitivity in 0D Organic‐Inorganic Hybrid Mn Halides

Abstract 0D organic‐inorganic hybrid manganese halides (OIHMnHs) are promising candidates for X‐ray detection due to their tunable crystal structures, low ionic mobility, and exceptional stability. However, inefficient charge transfer from isolated inorganic polyhedra limits their sensitivity. Accordingly, it is crucial to improve the carrier transport efficiency of 0D OIHMnHs to develop high‐sensitivity X‐ray detectors. Herein, 0D (4/2‐DMAP) 2 MnBr 4 (4/2‐DMAP + , 4/2‐dimethylaminopyridinium) single crystals (SCs) are designed and reported, where density functional theory (DFT) reveals that the A‐site cation is the primary contributor to the conduction band minimum (CBM), establishing multi‐dimensional carrier transport pathways between [MnBr 4 ] 2− and [4/2‐DMAP] + . Such architecture overcomes unidirectional carrier confinement inherent in conventional [MnBr 4 ] 2− polyhedra. Meanwhile, the introduction of a polar isomer design further enhances cation‐anion coupling interactions, effectively suppressing ionic migration while preserving structural integrity. Finally, the optimized detectors based on (4‐DMAP) 2 MnBr 4 SC achieved a high µτ product (1.16 × 10 −3 cm 2 V −1 ), exceptional sensitivity (13 547 µC Gy air −1 cm −2 ), and low limit of detection (13.1 nGy air s −1 ), which could achieve the highest reported sensitivity among OIHMnHs direct X‐ray detectors in low‐dose X‐ray imaging to date. This research establishes a foundation for advancing high‐sensitivity X‐ray detectors with low‐dose detection and commercial viability in medical imaging applications.