The inhomogeneity in conjugated polymer blend films

Conjugated polymer blend films are studied by time-resolved fluorescence and near-field scanning optical microscopy. Phase separations were directly observed by NSOM. The domains are found to be composed of different fractions of the two constituent polymers. The composition of the 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 low PdOPV ratio, the two polymers are mixed homogeneously. As the concentration of PdOPV increases, condensed phase of PdOPV is formed.