Preferred orientation of thin layers of conjugated polymers

By application of grazing incidence surface diffraction with synchrotron X-rays we have revealed that orientational anisotropy is ususally present in spin-coated and solution cast thin layers of conjugated polymers, an effect which is of great concequences for the use of such materials in light-emitting diodes. The kind and degree of preferred orientation depends upon factors like solvents used, the casting method and the degree of stereoregularity. Also thin layers deposited on top of water shows strong preferred orientation.