UV ‐aided graphene oxide reduction by TiO 2 towards TiO 2 /reduced graphene oxide composites for dye‐sensitized solar cells

Abstract

Electron transport layer is one of the important layer in the dye-sensitized solar cells (DSSCs) which is responsible for the transport of photo-generated electrons by the dye to the outer circuit. TiO2 has been widely used as electron transport material in DSSCs. However, improving the electrical conductivity of TiO2 without sacrificing the surface area is one of the important strategies to improve the efficiency of the DSSCs. Here graphene oxide (GO) is added as an additive into the TiO2 network towards the preparation of TiO2/reduced graphene oxide (RGO) composites by UV assisted photocatalytic reduction method. The RGO/TiO2 composites with different compositions of RGO were characterized and the performance of DSSCs using the prepared material as photoanode was studied. Furthermore, through the D and G band Raman peaks, the reduction of GO to RGO was confirmed. The optical properties of the prepared material were analyzed using UV-visible spectroscopy and photoluminescence analysis, respectively. The carrier lifetime of the TiO2 and TiO2/RGO composites was studied using time resolved photoluminescence studies. The high-resolution transmission electron microscope images of prepared TiO2/RGO composites were found to have sheet-like structure surrounding the near spherical nanoparticles, which could be attributed to that of RGO and TiO2, respectively. The binding energy states of the prepared material were studied using X-ray photoelectron spectroscopy (XPS) spectra. The incorporation of RGO in TiO2 was found to improve the Brunauer–Emmett–Teller (BET) surface area of TiO2 and distribution of pores in TiO2 and TiO2/RGO composites was found to be uniform. The DSSCs were fabricated using the prepared TiO2 and TiO2/RGO composites as photoanodes and their power conversion efficiencies were analyzed.