Ferrocene as a rapid charge regenerator in dye-sensitized solar cells
By Ahmed M. El-Zohry and Jiayan Cong and Martin Karlsson and Lars Kloo and Burkhard Zietz
Published in Dyes and Pigments
2016
Abstract
Using the reductive power of the ferrocene moiety (Fc), an ultrafast regeneration step via a covalent attachment of a Fc moiety to an organic triphenylamine-based dye (L1) when adsorbed on TiO2 is highlighted. Two modified dyes with one and two Fc moieties attached (L1Fc, and L1Fc2), respectively, were synthesized by addition to the \L1\ dye. These dyes have been studied spectroscopically using ultrafast transient absorption spectroscopy in the visible and the infrared (IR) regions. In acetonitrile, the results show an ultrafast excited state quenching of the modified dyes due to an expected electron transfer process from the Fc(s) to L1. Adsorbed onto TiO2, an electron transfer process is also detected from Fc to the oxidized dye (L1+). Despite the occurrence of an ultrafast regeneration step, the solar cell performance does not improve by the attachment of Fc(s) to the dye L1. Transient absorption measurements in the \IR\ region revealed a fast electron recombination process to the Fc+ moiety on an average time scale of ca. 300