Thermal Localization Enhanced Fast Photothermoelectric Response in a Quasi-one-dimensional Flexible NbS3 Photodetector.

Ultra-broadband photodetection is crucial for various applications like imaging and sensing, and has become a hot research topic in recent years. However, most of the reported ultra-broadband photodetectors can only cover the range from ultraviolet to infrared, which is insufficient. Herein, a photothermoelectric (PTE) detector made of NbS3 is reported. The device shows a considerable performance from ultraviolet to terahertz. For all examined wavelengths, the photoresponsivities are all larger than 1 VW-1 while the response time is less than 10 ms, much shorter than the reported ultra-broadband photodetectors made of millimetric scale graphene, ternary chalcogenide single crystal and other materials. The extraordinary performance is fully discussed and can be attributed to the thermal localization enhanced PTE effect. Due to the short thermal decay length and low thermal loss, the heat generated by the illumination is localized in only a micrometer scale along the channel and thus a strong PTE response is produced. In addition, the fabricated device also demonstrates robust flexibility and stability. Thanks to the quasi-one-dimensional structure, the NbS3 crystal is easy to be scaled down and thus intrinsically facilitate the integration of detectors. With these favorable merits, the quasi-one-dimensional NbS3 crystal holds promising potential in high-performance, ultra-broadband photodetectors.