Synergistic effect of interface engineering and bulk photovoltaic effect enhanced self-powered Ta2NiS5/<bold>α</bold>-In2Se3/WSe2 van der Waals heterojunction for photodetection

The discovery of van der Waals ferroelectric materials with narrow bandgaps has opened up opportunities for the extensive adoption of self-powered ferroelectric devices that rely on the bulk photovoltaic effect. However, it still needs to overcome the challenges related to the weak ferroelectric polarization and bulk photovoltaic effect in ultrathin van der Waals ferroelectric materials. In this report, we present a synergistic effect of interface engineering and bulk photovoltaic effect in the Ta2NiS5/alpha-In2Se3/WSe2 van der Waals heterojunction for photodetection. The heterojunction can detect the light with a wide range of wavelengths from near-ultraviolet to near-infrared without requiring external power sources. The output current density of the self-powered heterojunction shows a linear relationship with the optical power intensity at a specific wavelength. Moreover, it accurately identifies the wavelength of light at the same optical power intensity. The on/off ratio is 1.1 x 10(4), 3.9 x 10(4), 1 x 10(4), and 17, respectively, when the optical power density is 100 mW/cm(2) for 405, 660, 808, and 1064 nm light. The self-powered Ta2NiS5/alpha-In2Se3/WSe2 van der Waals photodetector exhibits high specific detectivity of 1.56 x 10(11), 1.79 x 10(12), 9.16 x 10(10), and 1.26 x 10(5) Jones for wavelengths of 405, 660, 808, and 1064 nm, respectively. These results validate our strategy for enhancing the detection performance in self-powered ferroelectric van der Waals photodetectors, thus opening up possibilities for future self-powered photodetection technologies.