title: Solvent evaporation induced liquid crystalline phase in poly(3-hexylthiophene).
abstract: We report on the evolution of the chain orientation of a representative π-conjugated polymer, poly(3-hexylthiophene) (P3HT), during the solution-casting process, as monitored using polarized Raman spectroscopy. These measurements point to the formation of a liquid-crystalline phase of P3HT solutions within a specific time period during solvent evaporation, which leads to a conducting channel. These conclusions are based on the angular dependence of polarized Raman scattering peaks, the anisotropy in the fluorescence background signal, analysis of the scattering-peak shape, and direct observations of the three-phase contact line in an optical microscope under crossed polarizers. These results shed new light on the evolution of chain alignment and thus materials nanostructure, specifically in solution-processed P3HT and more generally in π-conjugated systems. They may further enable the design of improved materials and processes for this important class of polymers.
authors.affiliation: School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA.
authors.forename: Min S
authors.initials: MS
authors.lastname: Park
authors.forename: Avishek
authors.initials: A
authors.lastname: Aiyar
authors.forename: Jung O
authors.initials: JO
authors.lastname: Park
authors.forename: Elsa
authors.initials: E
authors.lastname: Reichmanis
authors.forename: Mohan
authors.initials: M
authors.lastname: Srinivasarao