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

Abstract

Direct X-ray detection technology, owing to its rapid response, high spatial resolution and simple system configuration, has widespread applications in medical imaging, industrial non-destructive testing and scientific research. This drives the need for high-performance X-ray detection materials with 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 the nanorod-assembled Bi₂S₃ clusters, enhancing their structural and optoelectronic properties. Notably, the optimized Bi₂S₃-8% Se composite exhibited larger 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 Gy_air⁻¹ cm⁻², 3.5 times higher than that of pure Bi₂S₃. Furthermore, its detection limit was drastically reduced to 130 nGy_air 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.