Excited state biexcitons in monolayer WSe2 driven by vertically grown graphene nanosheets with high-density electron trapping edges.

Interface engineering in atomically thin transition metal dichalcogenides (TMDs) is becoming an important and powerful technique to alter their properties, enabling new optoelectronic applications and quantum devices. Interface engineering in a monolayer WSe₂ sample via introduction of high-density edges of standing structured graphene nanosheets (GNs) is realized. A strong photoluminescence (PL) emission peak from intravalley and intervalley trions at about 750 nm is observed at the room temperature, which indicated the heavily p-type doping of the monolayer WSe₂/thin graphene nanosheet-embedded carbon (TGNEC) film heterostructure. We also successfully triggered the emission of biexcitons (excited state biexciton) in a monolayer WSe₂, via the electron trapping centers of edge quantum wells of a TGNEC film. The PL emission of a monolayer WSe₂/GNEC film is quenched by capturing the photoexcited electrons to reduce the electron-hole recombination rate. This study can be an important benchmark for the extensive understanding of light—matter interaction in TMDs, and their dynamics. [ABSTRACT FROM AUTHOR]