High Performance of Broadband Photodetection via Topological PbBi ₂ Se ₄ Single Crystal

Abstract 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 PbBi ₂ Se ₄ 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 PbBi ₂ Se ₄ ‐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 × 10 ⁷ 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 PbBi ₂ Se ₄ crystal has great potential for applications in the next generation of optoelectronic devices.