Molecular and electronic structures of black dye; an efficient sensitizing dye for nanocrystalline TiO2 solar cells

One of the most efficient sensitizing dye called black dye for the dye-sensitized nanocrystalline TiO2 solar cells have been investigated by the density functional theory study. The microscopic mechanism of electron injection into TiO2 through the excited state(s) of the dye and electron acceptance from the redox system such as iodide by the oxidized dye molecule has been proposed. The excited electron, which is localized on the terpyridine ligand, can be efficiently injected into TiO2. The generated hole, which is localized on the S atom of NCS ligand, can be efficiently filled with the electron from the redox systems. These are the key reason why the sensitization of the black dye is remarkably efficient. (C) 2003 Elsevier B.V. All rights reserved.