With scientific and technological advances, Titanium dioxide (TiO 2 ) has attracted great research interest in the field of Dye Sensitized Solar cells (DSSC) with an aim to improve its efficiency. In this study, transparent semiconducting titanium dioxide thin films were deposited on glass substrate coated with fluorine tin IV oxide (SnO 2 : F) film by sol gel technique. The films were then annealed in air up to 450°C at different annealing rates. Optical reflectance was measured using UV-Vis-NIR spectrophotometer and optical parameters such as refractive index, extinction coefficient and dielectric constants were modelled using SCOUT software. Average refractive indices in the visible region ranged between 1.95 and 1.56. Porosity for as deposited, 1 step, 2°C/min and1°C/min were found to be 48%, 73%, 61% and 53% respectively. Refractive index dispersion was investigated using Wemple -Di-Domenico single oscillator model. Dispersion energy of annealed films increased from 5.90 eV to 11.30 eV. Surface and volume energy loss were computed from dielectric constants and correlated with porosity and dispersion energy as function of the heat treatment. Optical parameters were found to highly depend on the annealing the thin films. Annealing rate influenced a decrease in porosity and an increase in dispersion energy due to film densification and pore filling as the crystallinity is improved by heat treatment.

Increase in world population has led to more energy demand. Therefore, there is need for utilization of green and renewable energy. Dye sensitized solar cells (DSSCs) based on TiO 2 have attracted a lot of attention as an alternative source as compared to current silicon technology. In this study, TiO 2 thin films were deposited on doped fluorine tin oxide layer (FTO) glass substrates using sol-gel doctor blading technique. The films were annealed at different rates (1step, 2°C/min and 1°C/min) up to a temperature of 450°C followed by sintering at this temperature for 30 minutes. UV-VIS spectrophotometry was employed to probe the absorbance and reflectance of the films. It was found that, the optical parameters, such as the reflectance, the real (ε 1 ) and imaginary (ε 2 ) parts of dielectric constant, skin depth, Urbach energy and the energy gap; all depend on the annealing rate. The skin depth for the samples in visible region were found to increase from 6.319 x 10 -5 to 11.968 x 10 -5 cm -1 due to annealing. The Optical band energy (Eg) decreased from 5.04eV for as deposited film to 4.35eV at annealing rate of 1°C/min for direct allowed and from 2.76 to 2.56 eV for indirect transitions. Urbach tails in weak absorption region decreased with annealing rate. Urbach energies (Eu) were in the range of 432-505 meV for as deposited and annealed films. This was used to account for the disorder of the films. An inverse relation between Urbach energy and optical band energy as result of annealing rate was reported.