Solution-Processed Amorphous Zero-Dimensional Organic Metal Halide Hybrid Films for Direct X-Ray Detectors

Zero-dimensional (0D) organic metal halide hybrids (OMHHs) are emerging materials with significant potential for optoelectronic applications, including direct X-ray detectors. While 0D OMHH single crystals exhibit excellent X-ray detection properties, their scalability remains a significant challenge due to the time-intensive growth process and difficulty in producing large single crystals exceeding a few centimeters. This limitation hinders their practicality for large-area detector applications. Here, we report for the first time the development of amorphous 0D OMHH films via solution processing for efficient direct X-ray detection. By reacting a non-crystalline organic halide, triphenyl(9-phenyl-9H-carbazol-3-yl)phosphonium bromide (TPPCarzBr), with zinc bromide (ZnBr₂), we have successfully produced amorphous 0D (TPPCarz)₂ZnBr₄ films with controlled thickness via facile solution processing. The organic cations (TPPCarz⁺) feature a lower bandgap than the ZnBr₄ ^2- anions, enabling efficient molecular sensitization, where ZnBr₄ ^2- anions serve as X-ray absorbers and TPPCarz⁺ cations as charge transporters. Direct X-ray detectors based on 0D (TPPCarz)₂ZnBr₄ films demonstrate outstanding performance, achieving a stable X-ray detection sensitivity of 2,165 µC Gy_air⁻¹cm⁻² at 20 V mm⁻¹ and a detection limit of 6.01 nGy_air  s⁻¹. The amorphous nature of these films enhances their processability, allowing for fabrication in various sizes and shapes, and making them highly adaptable for scalable detector applications.