Defect study of TiO2 nanorods grown by a hydrothermal method through photoluminescence spectroscopy

This paper describes the photoluminescence study of titanium dioxide (TiO2) nanorods grown by a hydrothermal synthesis method on the surface of fluorine doped tin oxide (FTO) coated glass. The effects of growth conditions including: reaction time, precursor concentration and adding NaCl to hydrothermal solution on the structural and optical properties of productions are examined by using SEM, XRD, TEM and room temperature photoluminescence measurements. Also, the performance of the TiO2 nanorods as a photoanode of dye sensitized solar cells is investigated. The different excitation energies and intensities are chosen to verify the discrete electronic state of radiative recombination centers in nanorods. The photoluminescence studies show the profound effect of the excitation light energy and intensity on the emission spectra. The nanorods have extended emission spectra from UV to visible region. The near band edge emission is observed at 3.04±0.01 eV. Also, the spectra consist of high emission peaks around at 3.44 and 3.14 eV and other emissions at 2.90±0.01, 2.83±0.02, 2.70±0.01, 2.56, 2.36±0.03, 2.30±0.02, 2.03, and 1.66 eV. The photoluminescence study of TiO2 nanorods and photoconversion efficiency of dye sensitized solar cells indicate a correlation among some PL emission peaks, the aspect ratio and efficiency of photoanode based solar cells.