A high-performance and self-powered polarization-sensitive photoelectrochemical-type Bi 2 O 2 Te photodetector based on a quasi-solid-state gel electrolyte

Among the two-dimensional (2D) Bi O X (X = S, Se, and Te) series, Bi O Te has the smallest effective mass and the highest carrier mobility. However, Bi O Te has rarely been investigated, most likely due to the lack of feasible methods to synthesize 2D Bi O Te. Herein, 2D Bi O Te nanosheets are successfully synthesized by low-temperature oxidation of Bi Te nanosheets synthesized using a solvothermal method. The performance of a quasi-solid-state photoelectrochemical-type (PEC-type) photodetector based on 2D Bi O Te nanosheets is systematically investigated. Remarkably, the device has a high responsivity of 20.5 mA W (zero bias) and fast rise/fall times of 6/90 ms under 365 nm illumination, which is superior to the majority of PEC-type photodetectors based on bismuth-based compounds. More importantly, due to the strong anisotropy of 2D Bi O Te nanosheets, the device achieves a dichroic ratio as high as 52, which belongs to the state-of-the-art polarized photodetectors. Besides, the capacity of 2D Bi O Te for high-resolution polarization imaging is demonstrated. This work provides a promising strategy for the synthesis of 2D Bi O Te nanosheets to fabricate a high-performance and polarization-sensitive photodetector.