Lewis acid-doped transition metal dichalcogenides for ultraviolet–visible photodetectors

Ultraviolet photodetectors (UV PDs) are widely used in civilian, scientific, and military fields due to their high sensitivity and low false alarm rates. We present a temperature-dependent Lewis acid p-type doping method for transition metal dichalcogenides (TMDs), which can effectively be used to extend the optical response range. The p-type doping based on surface charge transfer involves the chemical adsorption of the Lewis acid SnCl4 as a light absorption layer on the surface of WS2, significantly enhancing its UV photodetection performance. Under 365 nm laser irradiation, WS2 PDs exhibit response speed of 24 ms/20 ms, responsivity of 660 mA/W, detectivity of 3.3 × 1011 Jones, and external quantum efficiency of 226%. Moreover, we successfully apply this doping method to other TMDs materials (such as MoS2, MoSe2, and WSe2) and fabricate WS2 lateral p–n heterojunction PDs.