Study of solvent-conjugated polymer interactions by polarized spectroscopy: MEH-PPV and Poly(9,9′-dioctylfluorene-2,7-diyl)

Absorption, emission, and anisotropy measurements were performed on poly-[2-methoxy-5(2′-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) and poly-(9,9′-dioctylfluorene-2,7-diyl) (PF) solutions of various solvents, and in thin films deposited from them. The good correlation of MEH-PPV absorption and emission energy with Hildebrandt's dispersive parameter indicate that dispersive forces regulate the effective extent of the luminophore. The excitation and the emission spectra of α and β chains can be distinguished in PF solutions using the steady-state anisotropy. PF films show greater memory effect from the solutions from which they were spun than MEH-PPV. Anisotropy of MEH-PPV is very low, both in solutions and in films reflecting efficient energy migration. Anisotropy of PF in solutions and films demonstrates great differences in energy transfer efficiency within the α and β phases, while there is no energy transfer between these chain conformations.