The Influence of Different Annealing Temperatures on Graphene-Modified TiO2 for Dye-Sensitized Solar Cell

In this study, graphene/TiO 2 composite films at different annealing temperatures from 450 to 650 °C acted as photoelectrode of dye-sensitized solar cell (DSSC). The graphene/TiO 2 composite films were characterized by scanning electronic microscopy, X-ray diffractometer, and electrochemical impedance spectroscopy. The Nyquist plot is built to simulate the redox reaction of internal device at the heterojunction by an equivalent circuit model. It is useful to analyze the component structure and promote photovoltaic conversion efficiency of DSSC. According to the experiment results, the optimal annealing temperature of graphene/TiO 2 composite film was 550 °C, where the open-circuit voltage was 0.74 ± 0.01 V, the short-circuit current density was 14.17 ± 0.32 mA/cm 2 , the fill factor was 51.00 ± 1.95%, and the photovoltaic conversion efficiency was 5.34 ± 0.12%.