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

BiS 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 BiS intrinsic defects. In this work, a simple and rapid method for the preparation of bismuth sulfide thin films and successfully prepare BiS with sulfur vacancies (S) (LA-BiS) and oxygen passivated (S) (AP-BiS) 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-BiS photodetectors exhibit responsivities of up to 2250 and 3.6 mA/W and detectivities of 1.69 × 10 and 2.6 × 10 cm·Hz W, while the AP-BiS photodetectors have ultra-fast on/off speeds of 1 ms and 8 ms, and on/off ratio up to 3 × 10. 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.