Enhanced Thermopower of Graphene Films with Oxygen Plasma Treatment

In this work, we show that the maximum thermopower of few layers graphene (FIG) films could be greatly enhanced up to similar to 700 mu V/K after oxygen plasma treatment. The electrical conductivities of these plasma treated FIG films remain high, for example, similar to 10(4) S/m, which results in power factors as high as similar to 4.5 x 10(-3) W K(-2) m(-1). In comparison, the pristine FLG films show a maximum thermopower of similar to 80 mu V/K with an electrical conductivity of similar to 5 x 10(4) S/m. The proposed mechanism Is due to generation of local disordered carbon that opens the band gap. Measured thermopowers of single-layer graphene (SLG) films and reduced graphene oxide (rGO) films were in the range of -40 to 50 and -10 to 20 mu V/K, respectively. However, such oxygen plasma treatment is not suitable for SLG and rGO films. The SIG films were easily destroyed during the treatment while the electrical conductivity of rGO films is too low.