Enhanced multiphoton emission from CdTe/ZnS quantum dots decorated on single-layer graphene

Time-resolved single-molecule spectroscopy of individual colloidal CdTe/ZnS quantum dots (QDs) decorated on single-layer graphene (SLG) demonstrates significantly enhanced probability of multiphoton emission, accompanied by reduced fluorescence intensity and decreased lifetime. A rigorous analysis of time-resolved spectroscopy on individual QDs on SLG reveals a decrease in radiative decay rate and a significant enhancement (12.6 times) in nonradiative decay rate. The enhanced multiphoton emission of QDs on SLG is a consequence of the competition between the enhanced nonradiative decay and fast Auger process, as suggested by the dominant fast decay (<0.8 ns) of QDs on SLG. Our findings provide important information on the emission behavior of QDs coupled with carbon nanomaterials, such as graphene and carbon nanotubes, and will assist in the creation of effective single-photon or multiphoton sources and devices. Furthermore, this is also a possible pathway for suppressing the Auger recombination of QDs while enhancing the generation of multicarriers, which has significant implications for light harvesting.