Ion implanted substitutionally dispersed Au in TiO2 nanostructures for efficient and stable dye sensitized solar cells

Various optical and electrical properties of noble metal doped TiO2 nanomaterials are found to vary remarkably with change in concentration and nature of doping. In the present work, ion implantation technique has been employed for generating substitutional and interstitial Au doping in TiO2 nanoparticle-nanofiber (NP-NF) composites. Experimentally, the presence of Au at substitutional and interstitial sites of TiO2 was detected through X-ray photoelectron spectroscopy. Depth profiling of implanted Au ions confirmed the presence of Au upto 70 nm. From the theoretical simulations, it was realized that substitutional Au doping results in higher strain and lower band gap contrary to pristine TiO2 and interstitial Au doped TiO2. Finally, the Dye sensitized solar cell (DSSC) prepared with substitutional doping was found to be 23.9% more efficient than interstitial Au based DSSC owing to enhanced light harvesting, higher fermi level and minimal recombinations as corroborated from current density-voltage and electrochemical impedance spectroscopy studies.