Formation of aligned periodic patterns during the crystallization of organic semiconductor thin films

Abstract

We report an approach to form periodic patterns in single layers of organic semiconductors by a simple annealing process. When heated, a crystallization front propagates across the film, producing a sinusoidal surface structure with wavelengths comparable to that of near-infrared light. These surface features initially form in the amorphous region within a micrometer of the crystal growth front, probably due to competition between crystal growth and surface mass transport. We demonstrate control over these patterns by varying processing conditions and substrate properties. This phenomenon could be exploited for the self-assembly of microstructured organic optoelectronic devices.