Enhanced Hot-Carrier Luminescence in Multilayer Reduced Graphene Oxide Nanospheres

摘要

We report a method to promote photoluminescence emission in graphenematerials by enhancing carrier scattering instead of directly modifying bandstructure in multilayer reduced graphene oxide (rGO) nanospheres. Weintentionally curl graphene layers to form nanospheres by reducing grapheneoxide with spherical polymer templates to manipulate the carrier scattering.These nanospheres produce hot-carrier luminescence with more than ten-foldimprovement of emission efficiency as compared to planar nanosheets. Withincreasing excitation power, hot-carrier luminescence from nanospheres exhibitsabnormal spectral redshift with dynamic feature associated to the strengthenedelectron-phonon coupling. These experimental results can be well understood byconsidering the screened Coulomb interactions. With increasing carrier density,the reduced screening effect promotes carrier scattering which enhanceshot-carrier emission from such multilayer rGO nanospheres. Thiscarrier-scattering scenario is further confirmed by pump-probe measurements.