THE INHOMOGENEITY IN CONJUGATED POLYMER BLEND FILMS

Conjugated polymer blend films are studied by time-resolved fluorescen ce and near-field scanning optical microscopy. Phase separations were directly observed by NSOM. The domains are found to be composed of dif ferent fractions of the two constituent polymers. The composition of t he domains and the domain structure alter as a function of blend ratio , Surface roughness and optical contrast exhibit similar trend at the change of blend ratio. At 4:1 ratio, both have higher contrasts. For l ow PdOPV ratio, the two polymers are mixed homogeneously. As the conce ntration of PdOPV increases, condensed phase of PdOPV is formed. (C) 1 998 Elsevier Science B.V. All rights reserved.