High Performance of Broadband Photodetection via Topological PbBi₂Se₄ Single Crystal

Broadband photodetectors are essential for capturing and identifying light information at various wavelengths, and they play a significant role in numerous areas such as agriculture, industry, and medicine. However, room-temperature detection with broadband capabilities and high performance is still limited by the unmatched bandgap and material quality. In this work, a high-quality PbBi₂Se₄ single crystal is successfully synthesized using an improved chemical vapor transport method and further achieve high-performance broadband photodetection from visible to terahertz regions. The fabricated photodetector enables infrared detection based on the photoexcited electron-hole pair transition, showing improvements in responsivity (≈1.16 A W⁻¹) and response speed (≈24 µs) by 1 and 3 orders of magnitude compared to the previously reported PbBi₂Se₄-based photodetector. It also achieves terahertz detection from 0.02 to 0.519 THz based on the EIW mechanism, with a high responsivity of 5.86 × 10⁷ V W⁻¹, a fast response speed of 6 µs, and the lowest noise equivalent power of 1.01 × 10⁻³ pW Hz^−1/2 among reported 2D materials at room temperature. Additionally, high-resolution terahertz transmission imaging is conducted to demonstrate the detector's excellent performance at room temperature. These results show that the PbBi₂Se₄ crystal has great potential for applications in the next generation of optoelectronic devices.