Static and ultrafast time-resolved fluorescent anisotropy in oriented Poly(3-hexylthiophene) films

We prepared highly oriented Poly(3-hexylthiophene) (P3HT) films by rubbing the surface of spin-coated polymer film. The polymer chains parallel to rubbing direction are in improved aggregation towards isotropic film, while the perpendicular ones have only weak aggregation. By supposing the Gaussian line shape angular distribution of aggregations, the distribution width is ∼0.305. Large inter-polarization energy difference suggests the possibility for energy transfer, which is found for tens of femtosecond. It is also found that the perpendicular excitation produces slower ground state recovery and longer exciton lifetime than parallel excitation.