High-performance ReSe2/PdSe2 polarized photodetectors with an ultrafast and broadband photoresponse

van der Waals heterostructures (vdWHs) fabricated by the stacking of transition-metal dichalcogenides (TMDCs) with different properties possess more significant properties beyond its individual materials, which allow them to provide excellent architectures for the optoelectronic devices. In this work, a novel polarized photodetector based on the ReSe2/PdSe2 heterostructure is constructed and explored thoroughly. The type-II band alignment is investigated by ultraviolet photoelectron spectroscopy (UPS), which facilitates the separation and transition of carriers. The device not only achieves a broadband response covering from near-ultraviolet to near-infrared, a high responsivity of 313 mA/W, but also a rapid photoswitching speed with rise/fall times about 70/82 & mu;s owing to the built-in electric field at the heterointerface, which is further confirmed by the large 3 dB frequency over 66.4 kHz. The main advantage offered by highly asymmetric crystal structure of ReSe2 and PdSe2 is the polarization detection. Therefore, the photodetector exhibits remarkable polarization performance with a dichroism ratio as high as 1.42 by tuning the bias voltage, which is capable of extracting polarized information, and improves the ability to operate in complex situations. These results reveal the great potential of the ReSe2/PdSe2 heterostructure for ultrafast, broadband and high-performance polarized detection, promising for military and civil applications.