Synthesis and characterization of Nb doped titania for dye sensitized solar cells

We report to reduce the recombination rate and photocatalytic activity in dye-sensitized solar cells (DSSCs) by doping titania with a transition metal, niobium (Nb). Nb doped titania (anatase) was synthesized by hydrothermal method. The synthesized powders were characterized by thermogravimetric analysis (TGA), X-ray diffraction (XRD), and finally they were used as photoanodes in DSSCs. TGA analysis reveals the presence of negligible amount of organics along with moisture. XRD analysis confirms the anatase phase with the presence of very small amount of brookite but free from rutile. It also confirms the inclusion of niobium in anatase structure. Fullprof profile matching was carried out to determine unit cell parameters, cell volume and amount of impurities. UV-Vis absorption spectra of the thin films were found to redshift in 10% Nb doping samples compared to the undoped and 20% doped TiO₂. DSSC devices using undoped TiO₂, 10% doped TiO₂ and 20% doped TiO₂ was fabricated and tested respectively. The results showed that Nb doped TiO₂ leads to higher device efficiency than the undoped TiO₂.