The electronic structure and thermoelectric properties of Bi2Te3 single crystals and graphene-doped Bi2Te3 polycrystalline samples were investigated with the aid of first-principles calculations, X-ray diffraction, scanning electron microscopy, Rietveld refinement, and thermal and transport measurements. It was found that the p electrons from the Bi and Te atoms are responsible for the density of states near the Fermi level. Experimental results show that the graphene-doped Bi2Te3 exhibits lower thermal conductivity and has a higher figure-of-merit than the single crystals. (C) 2010 Elsevier B.V. All rights reserved.