Photoluminescence and Raman studies of graphene thin films prepared by reduction of graphene oxide

Photoluminescence (PL) and Raman studies have been performed to investigate the optical properties of graphene thin films prepared by chemical and thermal reductions of graphene oxide (GO). The G peak in Raman spectra red-shifted after reduction of GO. Thermal reduction resulted in a more red-shift of the G peak than chemical reduction. A strong intensity of the D peak indicated that the prepared graphene films have significant structural disorders. A blue-shifted emission in PL spectra suggested that sp(2) clusters are embedded in a sp(3) matrix that acts as a tunnel barrier, causing a strong fluctuation in the local band gap. (C) 2009 Elsevier B.V. All rights reserved.