High-performance and broadband 2D ReS2/MoS2 semivertical heterojunction photodiodes

The emergence of two-dimensional van der Waals heterostructures has overcome the limitations of conventional heterostructure lattices and materials, opening new possibilities for the development of micro- and nanoscale photodiodes. To achieve a balance between the response speed and sensitivity in two-dimensional photodetectors, we designed a 2D ReS2/MoS2 semivertical heterojunction photodiode with a unilateral depletion region. This photodiode exhibits excellent self-powered capability, a broadband photovoltaic response of 532-785 nm, high responsivity (0.197A/W), power conversion efficiency (2.1%) and detectivity (10⩍12 Jones). In particular, the photodiode achieves an ultra-fast response time of 13/15 μs, enabling a detectable signal cut-off frequency of over 45 kHz. To further enhance the sensitivity of the photodiode under photovoltaic operation, we applied a layer of photosensitive PbS quantum dots (QDs) to the heterojunction and observed an approximately 21% improvement in device responsivity under 532 nm illumination. These findings highlight the potential of ReS2/MoS2 heterostructures for applications in high-performance photodiodes as well as solar cells.