WS2/Bi2O2Se van der Waals Heterostructure with Straddling Band Configuration for High Performances and Broadband Photodetector

Abstract 2D bismuth oxyselenide (Bi 2 O 2 Se) nanosheets have received increasing attention in the field of electronics and optoelectronics due to their high‐mobility, moderate energy bandgap, and air‐stability. However, due to the intrinsic high mobility, the photodetectors based on 2D Bi 2 O 2 Se have an inevitable high dark current, leading to high power consumption and limiting its potential application in photodetection. Herein, a novel highly sensitive WS 2 /Bi 2 O 2 Se van der Walls (vdWs) heterostructure with straddling band configuration is assembled on fluorophlogopite substrate. Owing to the effective separation of photogenerated electron–hole pairs and the quantum tunneling effect, the responsivity and external quantum efficiency of the WS 2 /Bi 2 O 2 Se heterostructure are 628 mA W −1 and 147.6% under 532 nm illumination, respectively. The I photo / I dark ratio with more than two orders of magnitude can be obtained, and the rise time is ≈33 ms, while the fall time is 38 ms. Furthermore, the heterostructure achieves a broadband photodetection capability from visible to near infrared (532–1450 nm). The results suggest that the WS 2 /Bi 2 O 2 Se vdWs heterostructure possesses a promising potential application prospect in high performance and broadband photodetectors.