Photoinduced Charge Transfer Properties of Donor and Acceptor substituted Iridium(III)-complexes
Efficient charge separation (CS) is one of the key steps in natural photosynthesis as well as in model systems and artificial photovoltaic devices.[1-4] Recently, we observed emission quenching when a cyclometalated iridium(III)-complex was substituted by two triarylamine (TAA) donors in the periphery of the phenylpyrazolyl ligands.[5,6] This is explained by the formation of an equilibrium of singulet and triplet charge separated state which result in a biexponential decay as proved by transient absorption spectroscopy.
Chart 1. Upper right: complexes under investigation; upper left: typical tansient absorption spetra of complex (1A_X) and bottom: energy state diagram of the complexes 1A_X.
[1] Balzani, V.; Credi, A.; Venturi, M. ChemSusChem 2008, 1, 26-58.
[2] Guldi, D. M. Chem. Soc. Rev. 2002, 22-36.
[3] Gust, D.; Moore, T. A.; Moore, A. L. Acc. Chem. Res. 2001, 34, 40-48.
[4] Wasielewski, M. R. Chem. Rev. 1992, 92, 435-461.
[5] Geiß, B.; Lambert, C. Chem. Commun. 2009, 1670-1672.
[6] Geiß, B.; Klein, J. H., Lambert, C.; Hrobárik, P.; Hrobáriková, V.; Kaupp, M. submitted.
