Ultrafast Charge Transfer and Valley Dynamics in WSe2/MoSe2 Heterostructure

Single layer (1L) transition metal dichalcogenides (TMDs) have attracted huge interest because of their peculiar optoelectronic properties and strong excitonic effects[1]. Van der Waals heterostructures, obtained by stacking two 1L-TMDs on top of each other, have been intensively investigated because of their possible applications in electronics and optoelectronics[2]. Of particular interest are type II TMDs heterostructures where the peculiar band alignment leads to a staggered gap (the valence band maximum and the conduction band minumum are in the same layer). The main reason is due to the fact that this kind of band alignment allows an efficient charge separation which is particularly beneficial for photovoltaics and solar cell technology based on atomically thick materials.