Capillary force induced phase separation in P3HT: PCBM thin films during selective solvent vapor annealing

In this paper, we report an efficient method for the phase separation of thin films composed of organic semiconductors. The phase behaviors of P3HT and PCBM blended films in confined geometries have been investigated under solvent selective vapor annealing. Anisole was used to generate the solvent vapor due to its differential activation of P3HT and PCBM. After the anisole vapor interacted with the mixed film, the molecular chains of the PCBM preferentially diffused and aggregated as a result of the capillary forces to form an ordered arrangement on the films surface. Ordered micron- and nano-scale phase separation structures were obtained using this methodology.