Dresden 2014 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 54: Poster Session 3
CPP 54.69: Poster
Donnerstag, 3. April 2014, 15:00–19:00, P2
Whispering gallery modes in spherical copolymers — •Daniel Braam1, Kenichi Tabata2, Günther M. Prinz1, Yohei Yamamoto2, and Axel Lorke1 — 1Experimentalphysik und CENIDE, Universität Duisburg-Essen — 2Faculty of Pure and Applied Sciences, University of Tsukuba, Japan
Copolymers are promising candidates for use in optoelectronic devices because of their cost efficiency and superior optical properties.
By combining polymers to π-conjugated alternating copolymers (e.g. F8TMT2 with fluorene and tiophene in the repeating units [1]), isotropic microspheres can be fabricated. By adjusting the formation parameters, their size can be tuned from some hundred nanometers to several micrometers. Laser excitation of a single sphere leads to a broad photoluminescence spectrum with superimposed narrow peaks. The number of observed peaks is dependent on the sphere diameter and they are attributed to standing waves on the inside of the sphere, known as whispering gallery modes (WGMs). The measured peak positions are in good agreement with theoretical calculations of TM- and TE-WGMs. This allows us to determine the copolymer’s relative permittivity.
The investigated π-conjugated alternating polymer particles combine the properties of a dye, a dielectric and a resonator. This opens up the possibility to build photonic crystals by arranging spheres with a distinct and narrow size distribution to match and amplify certain WGMs, aiming for novel optoelectronic properties.
[1] Taeko Adachi et al., J. Am. Chem. Soc. 135, 870 (2013)