Van der Waals Photodetector with an Integrated WS₂ Light-Harvesting Antenna

The responsivity of graphene-based photodetectors can be improved by forming heterostructures with other 2D materials and by further coupling to nanoparticles or quantum dots. In this study, we demonstrate that the photoresponse of a Graphene/MoSe₂/Graphene photodetector can be further enhanced by an external WS₂ bilayer acting as a light-harvesting antenna. The WS₂ bilayer is positioned outside the electronic pathway; thus, it does not directly contribute any photoexcited carriers. However, we observe a responsivity enhancement of up to 18 times, which can be explained by energy transfer from WS₂ to graphene and the MoSe₂ layer. Harnessing the excitonic properties of transition metal dichalcogenides (TMDs) as optical antennas defines a new strategy for photodetection.