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.