| Abstract
| - We measured the molecular order of poly(3-alkylthiophene) chains in thin films before and after melting throughthe combination of several polarized photon spectroscopies: infrared (IR) absorption, variable angle spectroscopicellipsometry (SE), and near-edge X-ray absorption fine structure (NEXAFS). The data from the various techniquescan be uniformly treated in the context of the dielectric constant tensor ε for the film. The combined spectroscopiesallow determination of the orientation distribution of the main-chain axis (SE and IR), the conjugated π system normal(NEXAFS), and the side-chain axis (IR). We find significant improvement in the backbone order of the films afterrecrystallization of the material at temperatures just below the melting temperature. Less aggressive thermal treatmentsare less effective. IR studies show that the changes in backbone structure occur without significant alteration of thestructure of the alkyl side chains. The data indicate that the side chains exhibit significant disorder for all filmsregardless of the thermal history of the sample.
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