Abstract
A high molar extinction coefficient charge transfer ruthenium sensitizer [Ru(4,-carboxylic acid-4′-carboxylate-2,2′-bipyridine)(4,4′-di-(2-(3,6-dimethoxyphenyl)ethenyl)-2,2′-bipyridine)(NCS)
2] anchored onto a nanocrystalline TiO
2 films achieve very efficient sensitization in the visible region yielding under AM 1.5 sunlight a short-circuit photocurrent density of 18.84
mA/cm
2, the open-circuit voltage was 783
mV and a fill factor of 0.73, corresponding to an overall conversion efficiency of 10.82%.
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A high molar extinction coefficient charge transfer sensitizer tetrabutylammonium [Ru(4,-carboxylic acid-4′-carboxylate-2,2′-bipyridine)(4,4′-di-(2-(3,6-dimethoxyphenyl)ethenyl)-2,2′-bipyridine)(NCS)
2], is developed which upon anchoring onto nanocrystalline TiO
2 films exhibit superior power conversion efficiency compared to the standard sensitizer bistetrabutylammonium
cis-dithiocyanatobis(4,4′-dicarboxylic acid-2,2′-bipyridine)ruthenium(II) (N719). The new sensitizer anchored TiO
2 films harvest visible light very efficiently over a large spectral range and produce a short-circuit photocurrent density of 18.84
mA/cm
2, open-circuit voltage 783
mV and fill factor 0.73, resulting remarkable solar-to-electric energy conversion efficiency (
η) 10.82, under Air Mass (AM) 1.5 sunlight. The Time Dependent Density Functional Theory (TDDFT) excited state calculations of the new sensitizer show that the first three HOMOs have ruthenium t
2g character with sizable contribution coming from the NCS ligands and the π-bonding orbitals of the 4,4′-di-(2-(3,6-dimethoxyphenyl)ethenyl)-2,2′-bipyridine. The LUMO is a π
* orbital localized on the 4,4′-dicarboxylic acid-2,2′-bipyridine ligand.