In Situ Spectroelectrochemical and Theoretical Study on the Oxidation of a 4H-Imidazole-Ruthenium Dye Adsorbed on Nanocrystalline TiO₂ Thin Film Electrodes

Title data

Zhang, Ying ; Kupfer, Stephan ; Zedler, Linda ; Bocklitz, Thomas ; Guthmuller, Julien ; Rau, Sven ; Dietzek, Benjamin:
In Situ Spectroelectrochemical and Theoretical Study on the Oxidation of a 4H-Imidazole-Ruthenium Dye Adsorbed on Nanocrystalline TiO₂ Thin Film Electrodes.
In: Physical Chemistry Chemical Physics. Vol. 17 (2015) Issue 44 . - pp. 29637-29646.
ISSN 1463-9084
DOI: https://doi.org/10.1039/C5CP04484G

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Abstract in another language

Terpyridine 4H-imidazole-ruthenium(ii) complexes are considered promising candidates for use as sensitizers in dye sensitized solar cells (DSSCs) by displaying broad absorption in the visible range, where the dominant absorption features are due to metal-to-ligand charge transfer (MLCT) transitions. The ruthenium(iii) intermediates resulting from photoinduced MLCT transitions are essential intermediates in the photoredox-cycle of the DSSC. However, their photophysics is much less studied compared to the ruthenium(ii) parent systems. To this end, the structural alterations accompanying one-electron oxidation of the RuIm dye series (including a non-carboxylic RuIm precursor, and, carboxylic RuImCOO in solution and anchored to a nanocrystalline TiO2 film) are investigated via in situ experimental and theoretical UV-Vis absorption and resonance Raman (RR) spectroelectrochemistry. The excellent agreement between the experimental and the TDDFT spectra derived in this work allows for an in-depth assignment of UV-Vis and RR spectral features of the dyes. A concordant pronounced wavelength dependence with respect to the charge transfer character has been observed for the model system RuIm, and both RuImCOO in solution and attached on the TiO2 surface. Excitation at long wavelengths leads to the population of ligand-to-metal charge transfer states, i.e. photoreduction of the central ruthenium(iii) ion, while high-energy excitation features an intra-ligand charge transfer state localized on the 4H-imidazole moiety. Therefore, these 4H-imidazole ruthenium complexes investigated here are potential multi-photoelectron donors. One electron is donated from MLCT states, and additionally, the 4H-imidazole ligand reveals electron-donating character with a significant contribution to the excited states of the ruthenium(iii) complexes upon blue-light irradiation.

Further data

Item Type:	Article in a journal
Refereed:	Yes
Institutions of the University:	Faculties > Faculty of Mathematics, Physics und Computer Science > Department of Computer Science > Lehrstuhl Künstliche Intelligenz in der Mikroskopie und Spektroskopie > Lehrstuhl Künstliche Intelligenz in der Mikroskopie und Spektroskopie - Univ.-Prof. Dr. Thomas Wilhelm Bocklitz
Result of work at the UBT:	No
DDC Subjects:	500 Science > 530 Physics
Date Deposited:	12 May 2023 07:28
Last Modified:	12 May 2023 07:28
URI:	https://eref.uni-bayreuth.de/id/eprint/76386