Investigation of low thermal reduction of graphene oxide for dye-sensitized solar cell counter electrode

Flake-type graphite was used for synthesizing graphene oxide (GO), which was then reduced to a few layers of graphene sheets by using a chemical or thermal reduction method. The surface morphology, phase crystallization, and defect states of the reduced graphene were determined using electron microscopy and X-ray diffraction and by using Raman and infrared spectra. Dye-sensitized solar cells with the synthesized graphene as the counter electrode were fabricated to evaluate the electrolyte activity and charge transport performance. Intercalated defects that are generally formed during the thermal reduction of GO were eliminated by increasing the reduction temperature. Furthermore, the product of the chemical reduction of GO was in the amorphous phase because substitutional Ti+ ions disrupted the graphene order. Electrochemical impedance spectra showed that increasing the thermal reduction temperature could yield thermally reduced GO with a lower charge transfer resistance, increase the electron lifetime, and result in an energy conversion efficiency of approximately 3.2%. (C) 2015 Elsevier B.V. All rights reserved.