Oligothiophene-containing coumarin dyes for efficient dye-sensitized solar cells.

We have developed oligothiophene-containing coumarin dyes fully functionalized for dye-sensitized nanocrystalline TiO(2) solar cells (DSSCs). DSSCs based on the dyes gave good performance in terms of incident photon-to-current conversion efficiency (IPCE) in the range of 400-800 nm. A solar energy-to-electricity conversion efficiency (eta) of 7.

Photophysical and (photo)electrochemical properties of a coumarin dye.

A new coumarin dye, cyano-{5,5-dimethyl-3-[2-(1,1,6,6-tetramethyl-10-oxo-2,3,5,6-tetrahydro-1H,4H,10H-11-oxa-3a-aza-benzo[de]anthracen-9-yl)vinyl]cyclohex-2-enylidene}-acetic acid (NKX-2753), was prepared and characterized with respect to photophysical and electrochemical properties. It was employed as a dye sensitizer in dye-sensitized solar cells and showed efficient photon-to-electron conversion properties. The photocurrent action spectrum exhibited a broad feature with a maximum incident photon-to-electron conversion efficiency (IPCE) of 84% at 540 nm, which is comparable to that for the famous red dye RuL2(NCS)2 (known as N3), where L stands for 2,2'-bipyridyl-4,4'-dicarboxylic acid.

Effect of additives on the photovoltaic performance of coumarin-dye-sensitized nanocrystalline TiO2 solar cells.

The effects of deoxycholic acid (DCA) and 4-tert-butylpyridine (TBP) as additives on the photovoltaic performance of coumarin-dye-sensitized nanocrystalline TiO2 solar cells were investigated. DCA coadsorption improved both the photocurrent and photovoltage of the solar cells, even though it decreased the amount of dye adsorbed on the TiO2 electrode. The improved photocurrent may arise from suppression of the deactivation of the excited state via quenching processes between dye molecules or a more negative LUMO level of the dye in the presence of DCA, resulting in a high electron-injection yield from the dye into TiO2.