Graphene oxide nanosheet wrapped white-emissive conjugated polymer nanoparticles.

We have demonstrated the preparation of white-emissive conjugated polymer nanoparticles wrapped with graphene oxide (GO) nanosheets. Highly stable, GO-wrapped, poly(9,9-di-n-octylfluorenyl-2,7-diyl) nanoparticles (GO-PFO NPs) with diameters in the range 30-150 nm were successfully obtained by utilizing the GO nanosheets as an interface stabilizer in an emulsification process. The synthesized GO-PFO NPs exhibited unique white-emitting photoluminescence with a characteristic green-emissive broad band above 500 nm, which was distinct from the photoluminescent behavior of PFO NPs without GO. This green emission was deduced to originate from the presence of the GO nanosheet shell surrounding the PFO NPs, rather than from luminescence of GO itself or formation of keto defects in the PFO chain. PL decay analysis showed that the GO-wrapped PFO NPs had a longer luminescence lifetime in comparison to PFO NPs without GO, and highly efficient energy transfer to lower energy state induced by the GO occurred.