Orientation-controlled growth of pentacene single crystal films on an alignment layer using liquid crystal as solvent

We found that organic semiconductor pentacene is soluble in some liquid crystal materials with large pi-electron conjugated groups. The solubility of pentacene in the heated cyanoterphenyl liquid crystal reached 20 wt%. We considered that. both elongated molecular structures of pentacene and liquid crystal produce temporary molecular aggregates in the solution. We also clarified that a large molecular-alignment-controlled thin plate of single crystal pentacene up to 200 mum in length can be grown on a rubbed alignment layer of polyimide when the heated solution film was slowly cooled between glass substrates.