Nanostructured composites of one-dimensional TiO2 and reduced graphene oxide for efficient dye-sensitized solar cells

Abstract

An effective photoanode is essential for an efficient dye-sensitized solar cell (DSSC). In this paper, composites of TiO2 nanotubes (or nanowires) and reduced graphene oxide (RGO) with different RGO contents are prepared through a hydrothermal method and applied as the photoanode for DSSCs. The composition, morphology, and photovoltaic performance of the composites were evaluated in detail. We show that the RGO content in the composite is a critical factor for the photovoltaic properties of devices constructed from these composites. The DSSC performance initially increases and then decreases with increasing RGO content of the composites. The morphology of the TiO2 nanostructure also has a profound impact on the DSSC performance. TiO2 nanotubes are more favorable than TiO2 nanowires for the construction of the composites in terms of DSSC performance. The DSSC based on the RGO- TiO2 nanotubes with 2% of RGO exhibits optimal performance with an overall energy conversion efficiency of 5.33%. The enhanced DSSC performance of the RGO- TiO2 nanotubes results from the facilitated electron transport at the RGO- TiO2/dye|electrolyte interface and improved dye adsorption on the photoanode.