Strong polarization sensitivity in a two-dimensional MoS2/WSe2 heterojunction for self-powered photodetection

Polarization-sensitive photodetectors have received considerable attention for their exceptional optoelectronic properties that depend on polarization. It is an excellent method to reduce energy consumption, system's sizes, and cost by constructing self-powered heterojunctions using the two-dimensional materials with asymmetry structure. In this report, we present a self-powered MoS2/WSe2 heterojunction capable of polarized photodetection. The heterojunction exhibits both photovoltaic and pyroelectric effects, which are correlated with the polarized signals. Interestingly, there is a 90° polarization angle between the photovoltaic and pyroelectric effects due to the introduction of in-plane structural polarization. The photovoltaic effect achieves the highest specific detectivity (D*) of about 5 × 1012 Jones when the light polarization is parallel to the in-plane structural polarization. Conversely, the pyroelectric effect dominates and yields the highest D* of about 6 × 109 Jones when the light polarization is perpendicular to the in-plane structural polarization. These findings demonstrate that the specific detectivity of the heterojunction can vary based on the orientation of the light polarization relative to the in-plane structural polarization due to distinct physical mechanisms. Moreover, the self-powered MoS2/WSe2 heterojunction enables simultaneous detection of optical power density and its change rate for polarized light. This study highlights the potential application of two-dimensional heterojunctions for polarization-sensitive self-powered photodetection in the future.