Aggregation quenching in thin films of MEH-PPV studied by near-field scanning optical microscopy and spectroscopy

Aggregates in thin films of conjugated polymers form excimer states and significantly reduce the photo- and electroluminescence efficiency in devices produced from these materials. We have studied the aggregate formation in thin films of poly(2-methoxy,5-(2′-ethyl-hexyloxy)-p-phenylene-vinylene) (MEH-PPV) by near-field scanning optical microscopy and spectroscopy. Local photoluminescence spectroscopy and photo-bleaching experiments have been used to show that thin films of MEH-PPV are homogeneously aggregated and do not form aggregated domains.