Growth and Characterization of AgBiS₂ Bulk Single Crystals for Near-Infrared Detectors

AgBiS2 nanocrystal films exhibit promising semiconductive properties when utilized in photovoltaic devices. However, theoretical calculations reflect a metallic band structure. Therefore, the inherent characteristics of this material have yet to be well understood. In the present work, large-scale and high-quality AgBiS2 monocrystals (φ20 × 45 mm3) have been successfully grown and utilized to reveal their band structures and opto-electrical properties. Both semiconducting and metallic properties were observed in bulk AgBiS2 single crystals, as evidenced by the performance of photoconductive and heterojunction photodetectors, respectively. Notably, the heterojunction device demonstrates a significant responsivity (5.03 mA W–1), a high detectivity (3.8 × 109 Jones), and a swift millisecond-level response time at 1920 nm. These findings suggest that semimetallic single crystals can also be an excellent candidate material for photodetection. The special properties make it have broad application prospects in high-performance long-wave infrared detection.