Effect of temperature on emission of MEH-PPV/PS solid-state solution

The polymer-polymer interaction of poly[2-methoxy-5-(2′-ethylhexyloxy)-1,4-p-phenylenevinylene] (MEH-PPV) in blends with polystyrene (PS) was studied. Photoluminescence spectra of blend films present a new well-resolved peak at 10 K, which appears at lower wavelengths, being associated to an intrachain transition. The emission line shape of MEH-PPV/PS blends was analyzed using a molecular exciton theory, supposing two radiative processes, allied to non-localized (aggregate states) and localized (intrachain) transitions. The temperature dependence of the intrachain transition shows an energy transfer process from localized to non-localized state above 180 K. The electronic structure based on the experimental results is discussed and the electronic-vibrational coupling parameter (Huang-Rhys factor) of MEH-PPV/PS blend was obtained.