Solvent and concentration effects on fluorescence emission in MEH-PPV solution

We systematically studied the excitation and the fluorescence steady-state spectroscopy of poly[2-methoxy-5-(2′-ethylhexoxy)- p-phenylene vinylene] (MEH-PPV) in two solvents and several concentrations. Fluorescence spectra were recorded for solutions in several concentrations (10 −5 mg/ml to 10 −3 mg/ml), showing that tetrahydrofuran (THF) and toluene solvate the polymer chain differently. Dilute solution (10 −5 mg/ml) in THF exhibit broader fluorescence spectra due to greater conformation disorder. The degree of the aggregation depends on both the solvent and the polymer concentration. Aggregation is promoted in toluene solution and hindered in THF solvent.