High-performance Bi₂S₃ photodetector based on oxygen-mediated defect engineering and its wafer-scale fast fabrication

Bi₂S₃ with a 2D van der Waals structure has attracted much attention due to its high conductivity, large absorption coefficient, and environmental friendliness. The preparation of tunable optoelectronic devices can be realized by exploiting and tuning Bi₂S₃ intrinsic defects. In this work, a simple and rapid method for the preparation of bismuth sulfide thin films and successfully prepare Bi₂S₃ with sulfur vacancies (S_vac) (LA-Bi₂S₃) and oxygen passivated (S_vac) (AP-Bi₂S₃) was presented. The defect state difference of the two devices leads to exhibit different optoelectronic properties. Under 638 nm and 1310 nm illuminations, the LA-Bi₂S₃ photodetectors exhibit responsivities of up to 2250 and 3.6 mA/W and detectivities of 1.69 × 10¹² and 2.6 × 10⁹ cm·Hz^1/2 W^-1, while the AP-Bi₂S₃ photodetectors have ultra-fast on/off speeds of 1 ms and 8 ms, and on/off ratio up to 3 × 10³. The preparation method of the tunable optoelectronic devices gives a new avenue for defect tuning in metal sulfides and for the preparation and application of optoelectronic devices.