title: Two-dimensional electronic excitations in self-assembled conjugated polymer nanocrystals
abstract: Several spectroscopic methods were applied to study the characteristic properties of the electronic excitations in thin films of regioregular and regiorandom polythiophene polymers. In the regioregular polymers, which form two-dimensional lamellar structures, increased interchain coupling strongly influences the traditional one-dimensional electronic properties of the polymer chains. The photogenerated charge excitations (polarons) show two-dimensional delocalization that results in a relatively small polaronic energy, multiple absorption bands in the gap where the lowest energy band becomes dominant, and associated infrared active vibrations with reverse absorption bands caused by electron-vibration interferences. The relatively weak absorption bands of the delocalized polaron in the visible and near-infrared spectral ranges may help to achieve laser action in nanocrystalline polymer devices using current injection.
authors.affiliation: Physics Department, University of Utah, Salt Lake City, UT 84112, USA.
authors.initials: R
authors.lastname: Osterbacka
authors.initials: CP
authors.lastname: An
authors.initials: XM
authors.lastname: Jiang
authors.initials: ZV
authors.lastname: Vardeny