The effect of UV-Irradiation (under Short-Circuit Condition) on dye-sensitized solar cells sensitized with a Ru-complex dye functionalized with a (diphenylamino)styryl-thiophen group

Abstract

A new ruthenium complex, cis-di(thiocyanato)(2, 2 ′ -bipyridine-4, 4 ′ -dicarboxylic acid)(4, 4 ′ -bis(2-(5-(2-(4-diphenylaminophenyl) ethenyl)-thiophen-2-yl)ethenyl)-2, 2 ′ -bipyridine)ruthenium(II) (named E322) has been synthesized for use in dye-sensitized solar cells (DSCs). Higher extinction coefficient and a broader absorption compared to the standard Ru-dye, N719, were aimed. DSCs were fabricated with E322, and the efficiency was 0.12 initially. (4.06 for N719, as reference). The efficiency was enhanced to 1.83 by exposing the cell under simulated sunlight containing UV-irradiation at short-circuit condition. The reasons of this enhancement are (1) enhanceing electron injection from sensitizer to TiO2 following a shift toward positive potentials of the conduction band of TiO2 by the adsorption of protons or cations from the sensitizer, or from the redox electrolyte and (2) improving the regeneration reaction of the oxidized dye by the redox electrolyte by the dissolution of aggregated dye from the surface of TiO 2 following the treatment. © 2009 Kazuteru Nonomura et al.