Crystalline structure of solution-processed pentacene thin films

We report on the crystalline structure of solution-processed pentacene thin films, prepared without using any precursors or derivatives. In these films, two types of surface structure were observed: flat domains and rough domains. The flat domains exhibited higher field effect mobilities than the rough domains and were composed of two-dimensional plate-like domains of several hundred micrometers containing large crystallites. The in-plane structures of the solution-processed thin films were analyzed by grazing-incidence X-ray diffraction (GIXD). The in-plane two-dimensional mapping of the GIXD patterns reveals that the solution-processed pentacene thin films have a crystal structure similar to that reported by Campbell et al. [Acta Crystallogr. 15 (1962) 289].