Tunable Polarity Behavior and Self-Driven Photoswitching in p-WSe2/n-WS2 Heterojunctions

Van der Waals (vdW) p–n heterojunctions consisting of various 2D layer compounds are fascinating new artificial materials that can possess novel physics and functionalities enabling the next‐generation of electronics and optoelectronics devices. Here, it is reported that the WSe2/WS2 p–n heterojunctions perform novel electrical transport properties such as distinct rectifying, ambipolar, and hysteresis characteristics. Intriguingly, the novel tunable polarity transition along a route of n‐“anti‐bipolar”–p‐ambipolar is observed in the WSe2/WS2 heterojunctions owing to the successive work of conducting channels of junctions, p‐WSe2 and n‐WS2 on the electrical transport of the whole systems. The type‐II band alignment obtained from first principle calculations and built‐in potential in this vdW heterojunction can also facilitate the efficient electron–hole separation, thus enabling the significant photovoltaic effect and a much enhanced self‐driven photoswitching response in this system. Van der Waals p–n heterojunctions consisting of WSe2 and WS2 layers exhibit a tunable polarity transition along a route of n‐“anti‐bipolar”–p‐ambipolar behaviors, owing to the successive work of conducting channels in the systems. Type‐II band alignment and built‐in potential also facilitate efficient electron–hole separation, thus enabling significant photovoltaic effect and much enhanced self‐driven photoswitching response.