Influence of Yb-Doped Nanoporous TiO₂ Films on Photovoltaic Performance of Dye-Sensitized Solar Cells

Yb-doped TiO₂ pastes with different Yb/TiO₂ weight ratios are prepared in the sol-gel process to obtain dye-sensitized solar cells (DSCs). The nanocrystalline size of Yb-TiO₂ becomes smaller and the lattice parameters change. Lattice distortion is observed and dark current is detected. It is found that a part of Yb existing as insulating oxide Yb₂O₃ state acts as barrier layers at the electrode--electrolyte interface to suppress charge recombination. A Yb-doped TiO₂ electrode applied in DSCs leads to a higher open-circuit voltage and a higher fill factor. How the Yb-doped TiO₂ films affect the photovoltaic response of DSCs is discussed.