Photophysics of a Ruthenium 4H‐Imidazole Panchromatic Dye in Interaction with Titanium Dioxide |
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| Authors: | Julian Schindler Dr Stephan Kupfer Dr Maria Wächtler Dr Julien Guthmuller Prof Dr Sven Rau Prof Dr Benjamin Dietzek |
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| Institution: | 1. Institute of Physical Chemistry and Abbe Center of Photonics, Friedrich Schiller University Jena, Helmholtzweg 4, 07743 Jena (Germany);2. Leibniz Institute of Photonic Technology (IPHT), Albert‐Einstein‐Strasse 9, 07745 Jena (Germany);3. Department of Theoretical Physics and Quantum Informatics, Gdansk University of Technology, Narutowicza 11/12, 80‐233 Gdansk (Poland);4. Institute of Inorganic Chemistry I, University Ulm, Albert‐Einstein‐Allee 11, 89081 Ulm (Germany);5. Jena Center for Soft Matter (JCSM), Philosophenweg 7, 07743 Jena (Germany) |
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| Abstract: | The photophysics of bis(4,4′‐di‐tert‐butyl‐2,2′‐bipyridine‐κ2N,N′)2‐(4‐carboxyphenyl)‐4,5‐bis(p‐tolylimino‐κN)imidazolato]ruthenium(II) hexafluorophosphate is investigated, both in solution and attached to a nanocrystalline TiO2 film. The studied substitution pattern of the 4H‐imidazole ligand is observed to block a photoinduced structural reorganization pathway within the 4H‐imidazole ligand that has been previously investigated. Protonation at the 4H‐imidazole ring decreases the excited‐state lifetime in solution. When the unprotonated dye is anchored to TiO2, photoinduced electron injection occurs from thermally nonrelaxed triplet metal‐to‐ligand charge transfer (3MLCT) states with a characteristic time constant of 0.5 ps and an injection efficiency of roughly 25 %. Electron injection from the subsequently populated thermalized 3MLCT state of the dye does not take place. The energy of this state seems to be lower than the conduction band edge of TiO2. |
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| Keywords: | charge carrier injection dyes/pigments photophysics ruthenium time‐resolved spectroscopy |
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