Surface morphology and optical properties of thin films of thiophene-based binary blends

We report on the relationship between optical and morphological properties of thin films of a blend of thiophene-based monomer and a diamine derivative. This system is of interest as it gives rise to white emission, due to the formation of exciplex energy levels in the solid state. The photoluminescence emission has been collected for different relative concentrations of the two blend components, and the film topography has been mapped correspondingly by means of atomic force microscopy. Along with a complex evolution of the film surface morphology, a significant variation of the emission properties has been observed upon change of the blend composition. In particular, the intensity of the broad low-energy exciplex band turns out to be affected by a balance of two factors, namely, the extension of homogeneous blend film areas, and their effective concentration. (c) 2005 American Institute of Physics.