Ruthenium Sensitizer Functionalized by Acetylacetone Anchoring Groups for Dye-Sensitized Solar Cells

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• 作者：Julien Warnan ; Victoire-Marie Guerin ; Fr茅d茅ric B. Anne ; Yann Pellegrin ; Errol Blart ; Denis Jacquemin ; Thierry Pauport茅 ; Fabrice Odobel
• 刊名：The Journal of Physical Chemistry C
• 出版年：2013
• 出版时间：May 2, 2013
• 年：2013
• 卷：117
• 期：17
• 页码：8652-8660
• 全文大小：386K
• 年卷期：v.117,no.17(May 2, 2013)
• ISSN：1932-7455

文摘

A new ruthenium sensitizer Ru-acac (cis-bis(thiocyanato)(2,2鈥?bipyridyl-4,4鈥?di(3-pentane-2,4-dione)(4,4鈥?dinonyl-2鈥?bipyridyl)ruthenium(II)) functionalized by acetylacetone (acac) anchoring groups was synthesized and studied in ZnO-based dye-sensitized solar cells (DSCs). In comparison with the parent ruthenium complex bearing classical carboxylic acid groups (coded Z907), Ru-acac exhibits blue-shifted metal-to-ligand charge transfer (MLCT) absorption and emission bands as well as a cathodic shifted oxidation potential (E(Ru^III/II)). Quantum chemistry time-dependent density functional theory (TD-DFT) calculations revealed that the acac groups are less conjugated with the pyridine units than carboxylic acid groups, entailing a lower electronic coupling with the semiconductor (SC) conduction band. Finally, the photovoltaic performances of both ruthenium complexes were investigated in DSCs by recording the J/V characteristics under solar spectrum simulation (AM1.5), the photoaction spectra, and by electrochemical impedance measurements. We showed that Z907 display higher photoconversion efficiency than Ru-acac owing to a lower electronic coupling with the SC and a different bending of the conduction band. Interestingly, the acac group provides a covalent binding to the ZnO surface but does not etch the structure as carboxylic acid usually does.