Efficient and economical dye-sensitized solar cells based on graphene/TiO2 nanocomposite as a photoanode and graphene as a Pt-free catalyst for counter electrode

Abstract

Dye-sensitized solar cells have been fabricated by employing graphene/TiO2 nanocomposites as photoanodes and graphene as a counter electrode. The mixing technique is used to prepare graphene/TiO2 nanocomposites. The dispersion of graphene in TiO2 is affirmed by transmission electron microscopy analysis. X-ray photoelectron spectroscopy is carried out to confirm the interstitial incorporation of carbon atoms in the TiO2 matrix through O TiC and TiOC surface states. The electrochemical activity and stability of graphene as a catalyst for counter electrode are investigated by cyclic voltammetry and chronoamperometry measurements. Solar cells fabricated are characterized by photocurrent–voltage characteristic, Incident photon-to-current efficiency, and electrochemical impedance spectroscopy analyses. The solar cell assembled with 0.08%GR-TiO2/N3/GR shows power conversion efficiency of 7.70%. This efficiency is superior to that of TiO2/N3/Pt based solar cell (7.28%). The improvement in efficiency can be attributed to a fast electron transport, improved light harvesting efficiency, and enhanced electron collection at photoanodes.