Effect of pressure on the fluorescence of poly[2-methoxy-5-(2′-ethylhexoxy)-p-phenylenevinylene]

The effect of pressure on both the steady state intensity and the lifetime of poly[2-methoxy-5-(2'-ethylhexoxy)p-phenylenevinylene] (MEH-PPV) has been measured for the neat polymer and at various dilutions in polystyrene (PS) and poly(methyl methacrylate) (PMMA). At 1 atm the efficiency increases with increasing dilution, especially in PS blends, and new peaks appear in the blends at higher energy. The lower energy peaks decrease in efficiency with pressure, The behavior of the higher energy bands is more complex. The decay rate is very rapid in the neat polymer. In general the decays in the blends are multiexponential. The differences in behavior in PS and PMMA blends can be explained by the greater compatibility of MEH-PPV in PS. In PMMA the MEH-PPV apparently tends to curl up to minimize the area of contact with the medium, leading to dissipation of energy by long-range intramolecular electron transfer.