A Bifunctional Tunneling Device for Photodetection and Electroluminescence Using van der Waals Heterostructure

Abstract

Two-dimensional (2D) materials are widely used in various optical, electronic, and optoelectronic devices. However, the realization of visible light emission and near-infrared photodetection functions in a single device remains a challenge. Here, an integrated dual-functional device is developed by manipulating the excitons of WS₂ within a graphene/hBN/WS₂/graphene heterostructure. When operating as a photodetector at low external bias, the dark current is well suppressed by the hBN layer. With the excellent two-photon absorption (TPA) property of monolayer WS₂, the photoresponse range of the photodetector can be extended to the near-infrared region, achieving a responsivity of up to 0.19 mA/W at 1145 nm. At high external bias, the device can work in light-emitting mode, in which the electroluminescence (EL) wavelength can be tuned via gate voltage. This atomically thin device opens up possibilities for applications in miniaturized display, sensing, and monitoring systems.