Chemically Synthesized Mesoporous Nitrogen-Doped TiO2 and its Application to High Efficiency Dye- Sensitized Solar Cells

Abstract

Nanosize mesoporous nitrogen-doped TiO2 (N-doped TiO2) has been synthesized by the sol gel method. The Hydrolysis approach for N-substituted titanium isopropoxide precursors has been proved with incorporation of nitrogen into the TiO2 matrix, which involves the direct binding of N to the central Ti ion. The light absorption onset shifts to the visible region at 550 nm with N-doped TiO2. The substitution of oxygen sites with nitrogen atoms in the titania structure was confirmed by X-ray photoemission spectroscopy (XPS). A clear decrease in the band gap of N-doped TiO2 (compared to Degussa P25) is deduced from the optical absorption spectroscopy results. Application of synthesized nanocrystalline Ndoped TiO2 to dye-sensitized solar cells resulted in 7.5% overall conversion efficiency, which was higher than the Degussa P25.