Effect of vacancy defect on optoelectronic properties of monolayer tungsten diselenide

Optoelectronic properties of pristine and vacancy defect monolayer tungsten diselenide (WSe2) have been investigated by the first principles calculations. The results predicate that Se defect monolayer WSe2 is direct semiconductor whereas the W defect monolayer WSe2 is metallic. The Se defect can decrease the work function for monolayer WSe2, however, the W defect can increase the work function for monolayer WSe2. The absorption edge for defect monolayer WSe2 occurs obviously red-shift, and the energy loss of electron transmitting in defect monolayer WSe2 is faster than pristine monolayer WSe2. The work gives a theoretical guidance for the fabrication of monolayer WSe2 optoelectronic nanodevices.