Optical and electrical studies of modified conjugated polymer films

A thin film preparation technique leading to reduced polaron formation in thin films of the polymer poly(m-phenylenevinylene-co-2,5-dioctyloxy-p-phenylenevinylene) [PmPV] was used to prepare thin films with significantly improved photoluminescence efficiency. This was achieved through increased interchain separation in films prepared using this technique. Photoinduced absorption measurements were performed to study the nature of the increased photoluminescence efficiency. The electrical transport properties of PmPV films prepared using this preparation technique were measured using both direct and alternating current measurement techniques and found to be improved for positive charge carriers and unchanged for negative charge carriers relative to conventional preparation techniques. The relative permittivity was shown to be greater in this film type, due to the longer delocalisation lengths resulting from increased interchain separation in these films. Fabrication of single layer light emitting devices utilising PmPV prepared using this technique were found to be significantly brighter and to have longer device operating lifetimes.