Flexible short-wavelength infrared photodetector based on extrinsic Sb2Se3

One-dimensional antimony selenide (Sb₂Se₃), enjoying intriguing optoelectronic properties, has drawn extensive attention in solar cells and broadband photodetection. Limited by the bandgap, the reported Sb₂Se₃ photodetectors always focus on the detection of visible and near-infrared (<1050 nm). Extending the detection waveband can greatly enrich the applications of Sb₂Se₃ photodetectors. Extrinsic photoconduction is an attractive strategy for extending the detection waveband, for example, the extrinsic Si detector for short-wavelength or long-wavelength infrared detection. However, Sb₂Se₃ extrinsic photoconduction has not been reported yet. Herein, the extrinsic photoconduction, attributed to the intrinsic point defects, is observed in Sb₂Se₃ for the first time, which induced a broadened short-wavelength infrared detection of 1650 nm at room temperature. Furthermore, the Sb₂Se₃ photodetector is fabricated on a flexible polyimide substrate. Meanwhile, the Sb₂Se₃ photodetectors also demonstrate a fast response speed (rise of 9 µs and fall of 11 µs), a high linear dynamic range of 98 dB, and wide -3dB bandwidth of 163 kHz at 1300 nm. This extrinsic-photoconduction provides feasible design strategies to broaden the detection waveband of the Sb₂Se₃ photodetectors and can be extended to other chalcogenides.