Proton insertion in polycrystalline WO3 studied with electron spectroscopy and semi-empirical calculations

Proton insertion in polycryst. tungsten oxide has been studied with photoelectron spectroscopy and semi-empirical calcns. The W 4f spectra show growth of W5+ and W4+ oxidn. states as a function of inserted proton content in the crystal lattice. A concomitant growth of bandgap structure displays two sep. peaks. Semi-empirical calcns. using the periodic large unit cell (LUC) method suggest the growth of W4+ states based on the total energy variation with respect to the no. of protons/unit cell. At this stage the general picture of insertion is that of a multiphase system contg. regions of different x values

High Light-to-Energy Conversion Efficiencies for Solar Cells Based on Nanostructured ZnO Electrodes

Photoelectrochem. properties of nanostructured ZnO thin film electrodes have been investigated in the UV and visible regions. For films consisting of 15 nm large undoped crystallites a max. monochromatic current conversion efficiency of 58% was obtained in the visible using a ruthenium-based dye as a sensitizer. The overall solar energy conversion efficiencies for this film was 2%. In comparison, sensitized films consisting of 150 nm large Al-doped crystallites yield a monochromatic current conversion efficiency of 31% and an overall solar energy conversion efficiency of 0.5%. The study also shows that nanostructured ZnO may give high efficiencies in the UV region, approaching unity for the Al-doped films

The electronic structure of the cis-bis(4,4'-dicarboxy-2,2'-bipyridine)-bis(isothiocyanato)ruthenium(II) complex and its ligand 2,2'-bipyridyl-4,4'-dicarboxylic acid studied with electron spectroscopy

The electronic structure of cis-bis(4,4'-dicarboxy-2,2'-bipyridine)bis(isothiocyanato)ruthenium(II) and of its ligand 2,2'-bipyridine-4,4'-dicarboxylic acid was studied with electron spectroscopy. Valence level spectra were studied with respect to photoelectron angular distributions and photon energy dependence. The exptl. information coupled with semi-empirical INDO/S calcns. provides a mapping of the orbital parentage of the dye complex and its ligands. The energy levels of the dye complex in the context of a sensitized semiconductor (nanostructured TiO2) surface are related to the bands of the semiconductor

Charge Transport in Solid-State Dye-Sensitized Solar Cells

A new model based on detailed numerical simulations is proposed to show how the doping of the electron transport material in solid-state dye-sensitized solar cells (ss-DSCs) changes the nature of carrier transport in the device. Differently from standard DSCs, where charge transport is fundamentally diffusive, in n-doped ss-DSCs, it becomes drift driven. The relevance of the internal electric field of the cell casts light on the influence of trap states within ss-DSCs