4. Conclusion
TiO2 thin films were fabricated to optimize the parameters for
good quality thin films for photo-degradation of dye. It was
found that 1a showed 95% degradation of methylene blue
under UV irradiation followed by 2c, 1c, 1d, 2a, 2b and 2d with
92–88% degradation while 1f and 2f degraded only 75% and
73% of the methylene blue. Transformation of phase from
anatase to rutile and increase in average crystallite size from
11.3 nm to 17.6 nm for films 1a–2f were observed as a function
of thickness (160.3 nm for 1a to 112.8 for 2f) and calcination
temperature. Refractive indices for samples were found to be
in the range of 2.49–3.45 with lowest extinction coefficient values.
All the films were highly transparent with transmittance
up to 85% in the visible region. The indirect band gap energy
for all samples was found to be in the range of 3.00–3.97 eV.
Moreover, Eg for samples showing good photocatalytic activity
were observed to be in the range of 3.25–3.65 eV.
Therefore, on the account of above studies it can be inferred
that these films are potential candidates for applications in
waste water treatment plants, anti reflective coatings and other
photo-induced catalytic reactions.