Picoseconds time resolved photoinduced absorption by infrared active vibrations as a probe for charge photogeneration in MEH-PPV/C60 composites

We have applied a visible pump mid-infrared probe picosecond time resolved technique, in order to study the photogeneration of charges in MEH-PPV/C60 composites. The photoinduced infrared active vibrations on the polymer chains have been used as a direct measure for the photogenerated charges. We have found that, within our time resolution of ⋍60 ps, polarons are photogenerated on the MEH-PPV chains with a quantum yield of the order of 5%.