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 wi th increasing dilution, especially in PS blends, and new peaks appear in th e blends at higher energy. The lower energy peaks decrease in efficiency wi th pressure, The behavior of the higher energy bands is more complex. The d ecay rate is very rapid in the neat polymer. In general the decays in the b lends are multiexponential. The differences in behavior in PS and PMMA blen ds 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 wit h the medium, leading to dissipation of energy by long-range intramolecular electron transfer.