Investigating the effect of conjugation in MEH-PPV

Solution state absorption and fluorescence of samples of fully and partiall y conjugated MEH-PPV at 77K and 300K have been measured to probe the distri bution of conjugated segments within the polymer. The absorption of the par tially conjugated polymer is at shorter wavelength and has a larger full wi dth at half maximum at all temperatures than that of the fully conjugated p olymer. The spectra are analysed by considering the polymer chain to be mad e up of a number of non interacting conjugated segments. Using this approac h it is possible to explain all the features seen in the spectra.