Ricerc@Sapienza

Mesoporous NiO films were deposited by means of a screen printing technique onto fluorine-doped tin oxide transparent electrodes and consequently sensitized with Erythrosin B (EryB) dye. The obtained colored NiO material was used as a working electrode in a three-electrode cell to study the evolution of the triple semiconductor/dye/electrolyte interface upon electrochemical polarization in dark conditions. The electrolyte was a solution of I3 -/I- in acetonitrile, with the redox couple representing the typical redox shuttle of dye-sensitized solar cells (DSCs).

The cost-effective production of chemicals in electrolytic cells and the conversion of the radiation energy into electrical energy in photoelectrochemical cells (PECs) require the use of electrodes with large surface area, which possess either electrocatalytic or photoelectrocatalytic properties. In this context nanostructured semiconductors are electrodic materials of great relevance because of the possibility of varying their photoelectrocatalytic properties in a controlled fashion via doping, dye-sensitization or modification of the conditions of deposition.

A new series of KuQuinones (KuQs) have been synthesized and employed as dye-sensitizers for NiO-based p-type dye-sensitized solar cells (p-DSSCs). KuQs are pentacyclic quinoid compounds which are characterized by a fully conjugated structure that is responsible for the strong and broad absorption in the visible spectrum. The HOMO/LUMO states of KuQs considered here have matching energy levels with the upper edge of the NiO valence band and I?/I3 ? redox potential energy. These features render such compounds suitable for NiO sensitization in p-DSSCs.

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).