Poly(3-hexylthiophene) (P3HT) was for covalently grafted on the graphene (GN) surface to form polymer brushes (P3HT-GN) via combining diazonium addition with Kumada catalysis-transfer polycondensation (KCTP).GNs was prepared according to the well-established oxidization-reduction method where the surfactant was used to prevent the reduced GNs from aggregation.The bromobenzene molecules were then grafted onto the GN surface through the diazonium addition at the presence of surfactant

which allowed immobilization of the initiator Ni(PPh3)4 on GNs and subsequent growth of P3HT following the KCTP mechanism.Atomic force microscopy and thermogravimetric analysis results indicate that the thickness and weight percentage of P3HT brushes grafted on GNs are 5 nm and 20.1 wt%

respectively.When assuming these P3HT chains were grafted on GNs in fully extended configurations

the grafting density was estimated to be one P3HT chain/6.53 nm2 with an average inter-chain distance of 2.556 nm.There is no visible characteristic X-ray diffraction peak in the scanning range of 3~60

indicating that these P3HT-grafted GNs are well exfoliated.UV-Vis spectra revealed that P3HT-GN had a weaker absorption peak than the pristine P3HT in the wavelength range of 300~500 nm

suggesting a significant interaction between P3HT and GN.This is consistent with the increased content of oxidized thiophene units observed in the X-ray photoelectron spectroscopy of P3HT-GN relative to that of the pristine P3HT.The strong interaction between P3HT and GN made the photo-induced fluorescence nearly quenched completely.The obtained quantum yield for P3HT-GN is 0.042% (only an eightieth of the pristine P3HT quantum yield)

exhibiting an extraordinary charge transfer efficiency between P3HT and GN.This opens up a new pathway for developing novel

high-efficient graphene-based functional materials.