Photophysical Study of Perylene/TiO2 and Perylene/ZnO Varying Interfacial Couplings and the Chemical Environment

• Published in: Journal of physical chemistry. C Vol. 115; no. 13; pp. 5683 - 5691
• Main Authors: Neubauer, Antje, Szarko, Jodi M, Bartelt, Andreas F, Eichberger, Rainer, Hannappel, Thomas
• Format: Journal Article
• Language: English
• Published: American Chemical Society 07.04.2011
• Subjects: C: Surfaces, Interfaces, Catalysis
• ISSN: 1932-7447; 1932-7455
• DOI: 10.1021/jp109615b

The impact of the chemical environment on heterogeneous electron transfer processes of two perylene derivatives chemically bound to ZnO or TiO2 colloids in a film was investigated by means of absorption and fluorescence spectroscopy. The perylene molecules varied in their electronic coupling between the perylene moiety and a carboxylic acid group, which also bound the perylene dyes to the semiconductor surface. Significantly different excited state dipole moments for the two perylene derivatives were found for certain perylene−solvent interactions and were attributed to different intramolecular charge transfer characters of the excited state. It is concluded that lifetime broadening due to ultrafast electron injection plays only a minor role in explaining the observed strong broadening of the absorption spectra for the hybrid systems with strong electronic coupling. Rather, a strong environmental effect of the colloidal semiconductor has to be taken into account for the hybrid systems with strong interfacial couplings.