Type‑I heterostructure based on ReSe2/PtS2 for self-powered and broadband UV–NIR photodetectors

Immense potential has been demonstrated by photodetectors based on two-dimensional (2D) van der Waals heterostructures (vdWHs), positioning them as a transformative technology for numerous applications in modern nanotechnology. However, 2D vdWHs photodetectors based on photoconductive effects require an external power input and are often accompanied by a large dark current, which hinders the development of miniaturization and portability of devices and greatly limits the application of devices in complex environments. In this paper, a type-Ι self-powered polarization-sensitive photodetector based on ReSe₂/PtS₂ van der Waals heterojunction is constructed, which has excellent photovoltaic characteristics. The type-I band alignment facilitates the collection of photogenerated holes from the ReSe₂ layer by the PtS₂ layer, thereby inhibiting carrier recombination. Enabled by the strong built-in electric field, a self-powered photoresponse with a wide spectrum from 365 to 1064 nm is realized. At zero bias voltage, the device achieves a high detectivity of 1.96 × 10¹¹ Jones and a high light on/off ratio of over 10⁴ under the irradiation of 685 nm light. It also has a fast response speed of 4/4 ms and the photocurrent anisotropy ratio reaches 1.2 at 638 nm light. In addition, we verified the device’s polarization imaging capability. This work paves the way for the development of high-performance type-Ι photodetectors with self-powered polarization-sensitive light detection and polarization imaging capabilities.