Ultrafast-Speed, High-Response, and Broadband WSe₂-Based Photodetector Achieved by Integrating Activated ZnO QDs

The two-dimensional/zero-dimensional (2D/0D) hybrid heterojunctions, based on transition-metal dichalcogenides (TMDCs), have attracted increasing attention in broadband photodetectors. As efficient light absorbers, the ultraviolet/near-infrared (UV/NIR)-absorbing quantum dots (QDs) can inject photocarriers into TMDCs, thereby extending the detection range of the photodetector. However, the QDs intended to broaden the spectral detection range do not effectively enhance the visible-light detection capabilities of TMDCs, resulting in a remaining deficient performance in the broadband photodetectors. Herein, we used activated ZnO QDs rich in surface oxygen vacancy defects to construct a high-performance broadband photodetector. By introducing surface oxygen vacancy defects as “self-doping” to adjust the band levels of ZnO, we achieved the heterojunction interface with efficient carrier separation. The photodetector exhibited a high responsivity of 1055.5 A/W and a high detectivity of 1.98 × 1011 Jones. In particular, the photodetector demonstrated an ultrafast response time of 50 ns, surpassing that of most other 2D/0D hybrid photodetectors based on TMDCs. The innovative device design can provide an avenue for promoting the evolution of high-performance broadband devices based on 2D/0D hybrid heterojunctions.