Heterostructure engineering of rod-like Bi2S3/Bi2Se3 composites for high-sensitivity direct X-ray detection with ultra-low detection limit

Direct X-ray detection technology, enabled by its rapid response, high special resolution and simple system configuration, has witnessed widespread applications in medical imaging, industrial non-destructive testing and scientific research. This drives the need for high-performance X-ray detection materials aiming for high sensitivity and low detection limits. Sulfides face significant challenges in X-ray detection performance due to the low atomic number of sulfur, intrinsic defects such as sulfur vacancies, and surface oxidation susceptibility. Herein, a series of rod-like clustered Bi2S3/Bi2Se3 composites with tunable S/Se molar ratios were synthesized via a facile hydrothermal method. Precise control of Se incorporation effectively modulated the morphology of nanorod-assembled Bi2S3 clusters, enhancing their structural and optoelectronic properties. Notably, the optimized Bi2S3-8% Se composite exhibited enlarged dimensions and denser nanorod clusters, leading to significantly improved X-ray detection performance. Under 40 kV X-ray irradiation, detectors based on Bi2S3-8% Se pellets achieved a remarkable sensitivity of 1025.37 μC·Gyair-1·cm-2, representing 3.5 times higher than pure Bi2S3. Furthermore, its detection limit was drastically reduced to 130 nGyair·s-1. The enhanced performance is attributed to the formation of Bi2S3/Bi2Se3 heterostructures, which facilitate efficient charge separation and transport, thereby boosting X-ray photoconversion efficiency. These findings highlight the potential of Bi2S3/Bi2Se3 composites as high-performance direct X-ray detectors, offering a promising strategy for developing advanced radiation detection materials.