Ricerc@Sapienza

High-performance dyes routinely employed in TiO2-based dye-sensitized solar
cells (DSSCs) were tested in cells assembled using Nb2O5 nanostructure-based photoanodes.
The sensitizers were chosen among both metal-complex (two Ru-based, N749 and C106, and one
Zn-based dye, DNF12) and metal-free organic dyes (DNF01, DNF11 and DNF15). Two different
sensitization processes were performed: the one commonly used for TiO2 photoanodes, and a new
process relying on high pressure by autoclavation. The assembled cells were characterized by current

X-ray photoelectron spectroscopy is a powerful tool for the characterization of molecular and hybrid solar cells. This technique allows for atomic-level characterization of their components as well as for the determination of the electronic structure that governs the key conversion processes. In this chapter, we introduce the basic concepts of electronic structure in molecules and semiconducting materials followed by a description of the concepts of photoelectron spectroscopy and how they relate to electronic structure.

We report here on the synthesis of four novel pyran-based DSSC photosensitizers. The dyes are constituted of a pyran core functionalized with different electron acceptor groups and with peripheral cyano-acrylic groups. The molecules were carefully characterized for what concerns optical and electrochemical properties and a clear dependence from the strength of the electron-acceptor group functionalizing the pyran core was observed. A detailed DFT analysis on the dyes gave a better insight of the electronic properties and showed a good accord with the experimental properties.

Screen-printed NiO electrodes were sensitized with 11 different dyes and the respective
electrochemical properties were analyzed in a three-electrode cell with the techniques of cyclic
voltammetry and electrochemical impedance spectroscopy. The dye sensitizers of NiO were organic
molecules of different types (e.g., squaraines, coumarins, and derivatives of triphenyl-amines and
erythrosine B), which were previously employed as sensitizers of the same oxide in dye-sensitized

Mesoporous submicrometric particles of orthorhombic Nb2O5 were prepared by a very simple route
consisting in the hydrolysis of niobium ethoxide Nb(OEt)5 in an alcoholic medium containing 1-
hexadecylamine as structure-directing agent followed by a hydrothermal treatment. The effects
related to the variation of the length of the aliphatic chain of the alcohol solvent (C2 to C4) and the
ramification of the alcohol (primary, secondary and tertiary), as well as the reactants to solvent ratio

In this work we present the electrochemical and photoelectrochemical characterization of NiO thin films [thickness (l) range: 2 <= l <= 4 mu m], which have been obtained from screen-printing of three precursor-pastes. All three pastes contained preformed NiO nanoparticles [diameter ((MT SET)) range: 20 < ((MT SET)) < 50 nm], but differed for the content and nature of the acidic component. The resulting NiO samples were employed as photoactive cathodes of p-type dye-sensitized solar cells (p-DSCs).