Sensitiser dye

Fig. 2. The effect of a sensitising dye (lT -Tieth5i-2,2 -cyariiQe iodide) on the absorption spectra of (a) AgCl, (b) AgBr, and (c) Ag(Br,I) crystals...

Nanoparticles of Ti02 are deposited on to a glass support covered with a transparent conducting layer of tin-doped indium oxide (ITO). Each nanoparticle is coated with a monolayer of sensitising dye based on Ru(II). Photoexcitation of the dye results in the injection of an electron into the CB of the semiconductor. 

In order to regenerate the sensitising dye from its oxidised form, a mediator is employed. An organic solvent containing the iodide/triiodide couple is used as the mediator, by which the electron flow at the platinum counter-electrode reduces triiodide to iodide, which in turn reduces Ru(III) to Ru(II). 

The dyes that perform this function are called spectral sensitisers because they are used to sensitise the photographic emulsion to light across the whole visible spectrum and beyond. Since silver halides are naturally blue sensitive, the green and red spectral sensitiser dyes must also be able to reduce the natural sensitivity of the silver halide emulsion to blue light. The most important class of compounds used in this... 

Many dienes and simple olefins are auto-oxidised in the presence of a sensitising dye such as haematoporphyrin, eosin, or methylene blue / 5,dS], The dye first suffers photo-excitation by light in the visible region, and two mechanisms have been considered for the subsequent activation of molecular oxygen by the excited dye. These may be represented schematically as ... 

The high surface area of the mesoporous metal oxide film is critical to efficient device performance as it allows strong absorption of solar irradiation to be achieved by only a monolayer of adsorbed sensitiser dye. Whereas a dye monolayer absorbed on a flat interface exhibits only negligible light absorption (the optical absorption... 

Figure 8.1 Schematic of a liquid electrolyte dye-sensitised solar cell. Photoexcitation of the sensitiser dye is followed by electron injection into the conduction band of the mesoporous oxide semiconductor, and electron transport through the metal oxide film to the TCO-coated glass working electrode. The dye molecule is regenerated by the redox system, which is itself regenerated at the platinised counter electrode...

A chain (Sj, ) mechanism is proposed for the light initiated substitution of halogen by sulphite in halo-substituted naphthols. The reaction is initiated by electron transfer from sulphite to an excited sensitiser dye. The sulphite anion radical produced then attacks the halonaphthol loss of halide from this species to give the product is coupled with electron transfer from a second sulphite, so propagating the chain. 

Merocyanine based spectral sensitising dye for photographic material... 

Blue organic sensitiser dye for DSCs. Device efficiencies of ca. 4.5 % have been achieved in a single dye system has shown promise for use in co-sensitised DSC devices with 1/ 8 % in combination with the Ru dye N719 [160). 

Solid-state redox mediators or hole conductor materials would make it possible to construct completely solid-state DSSCs that will probably have considerable added commercial value. One of the main difficulties in substituting liquid electrolytes is the need for an interpenetration of the sensitised metal oxide by the electrolyte, in order to have efficient contact between the sensitiser cation (the hole) and the mediator. Additionally, prospective solid hole collectors should have the following properties the valence band of the hole collector material must be located above the bottom of the sensitiser dye ground state it must be transparent throughout the visible spectrum, where the dye absorbs fight and the deposition of the solid material should be done without degrading the monolayer of sensitiser dye adsorbed on Ti02. 

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