Regensburg 2013 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 24: Organic Semiconductors
CPP 24.6: Vortrag
Mittwoch, 13. März 2013, 11:00–11:15, H40
Unraveling the structure/function-relationship of poly(3-hexyl thiophene) by single-molecule spectroscopy — •Florian Steiner1, Jan Vogelsang1,3, and John Lupton1,2 — 1Universität Regensburg — 2University of Utah — 3University of Texas at Austin
Poly(3-hexyl thiophene) (P3HT) has been used for many years for organic solar cells and field-effect transistors due to effective intermolecular selforganization in bulk films. It has been shown that the optical properties strongly depend on the processing conditions. Using single-molecule spectroscopic techniques we are able to link the conformation of the P3HT chains embedded in a host matrix with their photophysical properties. We show that the conformation of a single polymer chain can be influenced by the polarity of the environment, which has been identified by measuring the excitation polarization dependence by wide-field fluorescence microscopy. Additionally, by performing confocal microscopy we could relate the conformation to specific fluorescence characteristics: an ordered conformation leads to a large red-shift of the fluorescence emission of more than 100 nm, accompanied by strong photon anti-bunching, longer fluorescence lifetime and a decrease of the fluorescence quantum yield as compared to a disordered conformation. The data clearly exemplifies the large conformational and spectroscopic variability of P3HT at the single molecule level. We propose that the vast unprecedented variability in single-chromophore transition energies actually drives selforganization in the solid, offering a challenge for future materials and device optimization.