title: Structure of P3HT crystals, thin films, and solutions by UV/Vis spectral analysis.
abstract: Optical absorption spectra of poly(3-hexylthiophene) (P3HT) are calculated in solution, spin-coated thin films, and the bulk crystal using a multiscale simulation approach. The structure of the amorphous thin film is obtained from coarse grained molecular dynamics (MD) simulations and subsequent back-mapping onto an atomistic force field representation. The absorption spectra are computed using TDDFT by statistically averaging over an ensemble of molecules taken from the MD simulations. Experimental UV/Vis spectra of spin-coated thin films and solutions are recorded with varying ratios of 'good' versus 'poor' solvent. The theoretical approach is able to faithfully predict the spectral position in the various phases and offers fundamental insight into the cause of any spectral shifts. The position of the main absorption peak is found to be chiefly determined by the level of torsion between the thiophene rings inside each molecule, while intermolecular effects are less important. Hence, optical absorption spectra hold valuable clues about the microscopic structure of disordered P3HT phases.
authors.affiliation: Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster and Center for Multiscale Theory & Computation, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany. marcus.boeckmann@uni-muenster.de.
authors.forename: Marcus
authors.initials: M
authors.lastname: Böckmann
authors.affiliation: Institut für Angewandte Physik, Westfälische Wilhelms-Universität Münster, Corrensstr. 2/4, 48149 Münster, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Schemme
authors.affiliation: Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster and Center for Multiscale Theory & Computation, Corrensstr. 28/30, 48149 Münster, Germany.
authors.forename: Djurre H
authors.initials: DH
authors.lastname: de Jong
authors.affiliation: Institut für Angewandte Physik, Westfälische Wilhelms-Universität Münster, Corrensstr. 2/4, 48149 Münster, Germany.
authors.forename: Cornelia
authors.initials: C
authors.lastname: Denz
authors.affiliation: Institut für Physikalische Chemie, Westfälische Wilhelms-Universität Münster and Center for Multiscale Theory & Computation, Corrensstr. 28/30, 48149 Münster, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Heuer
authors.affiliation: Institut für Festkörpertheorie, Westfälische Wilhelms-Universität Münster and Center for Multiscale Theory & Computation, Wilhelm-Klemm-Str. 10, 48149 Münster, Germany. marcus.boeckmann@uni-muenster.de.
authors.forename: Nikos L
authors.initials: NL
authors.lastname: Doltsinis