Semiconducting Organic Metal Halide Complex Glasses for Efficient X-Ray Detection

The growing demand for efficient, low-cost, and scalable direct X-ray detectors has prompted the exploration of materials beyond conventional inorganic semiconductors, e.g., Si, α-Se, and Cd(Zn)Te. While organic semiconductors offer attractive features, including mechanical flexibility and low-temperature solution processability, they often fall short in sensitivity, energy resolution, and detection limits compared to their inorganic counterparts. Here, the first demonstration of direct X-ray detectors is reported based on a new class of materials, organic metal halide complexes (OMHCs), which are composed of metal halide species covalently bonded to organic semiconducting units. Specifically, 4-(4-(diphenylamino) phenyl)-1-(propyl)-pyridinium zinc bromide ((TPA-Py)₂ZnBr₂) is employed in its glassy form to fabricate high-performance direct X-ray detectors. By applying a facile melt-processing approach, wet-chemistry-synthesized (TPA-Py)₂ZnBr₂ single crystals can be easily transformed into air-stable glassy samples with tunable dimensions for device integration. The resulting glassy OMHC-based X-ray detectors exhibit outstanding performance, including a high dark resistivity (5.37 × 10¹¹ Ω cm), an excellent detection sensitivity (2,020 µC Gy_air⁻¹ cm⁻²) at an electric field of 10 V mm⁻¹, and an ultralow detection limit of 12.44 nGy_air s⁻¹. These results establish semiconducting OMHC glasses as a highly promising new class of materials for direct X-ray detectors.