Electrical and optical properties of conducting polymer-fullerene and conducting polymer-carbon nanotube composites

Various novel photo-physical properties such as a drastic photoluminescence quenching and photoconductivity enhancement and a photo-induced enhancement of low-field microwave absorption due to a highly effective photo-induced electron transfer have been observed in various conducting polymers doped with fullerenes and also acceptor-type molecules and conducting polymers. New types of junction devices utilizing effective charge separation at the interface of conducting polymer/C-60, C-60-doped conducting polymer/C-60 and acceptor type conducting polymer / donor type conducting polymer have been proposed and their novel characteristics have been demonstrated. Novel concepts such as an interpenetrating network, a condensed interface and the effect of introduction of photo-harvesting antenna molecule at the interface have been discussed. Nano-composite films of carbon nanotube (NT) and conducting polymer were prepared. With increasing the volume fraction of NT in conducting polymer the conductivity increases drastically at relatively low concentration of NT, which can be explained in terms of conduction by percolation process. Enhancement of photoconductivity of composite films has been found at near percolation threshold. Heterojunctions made of carbon NT and conducting polymer have also been found to be photosensitive.