The effect of transfer printing on pentacene thin-film crystal structure

The thermal deposition and transfer printing method had been used to produce pentacene thin films on SiO2∕Si and plastic substrates poly(methyl methacrylate) (PMMA) and poly(vinyl pyridine), respectively. X-ray diffraction patterns of pentacene thin films showed reflections associated with highly ordered polycrystalline films and a coexistence of two polymorph phases classified by their d spacing, d(001): 14.4 and 15.4A. The dependence of the c-axis correlation length and the phase fraction on the film thickness and printing temperature were measured. A transition from the 15.4A phase towards 14.4A phase was also observed with increasing film thickness. An increase in the c-axis correlation length of approximately 12%–16% was observed for pentacene (Pn) films transfer printed onto a PMMA coated poly(ethylene terephthalate) substrate at 100–120°C as compared to as-grown Pn films on SiO2∕Si substrates. The transfer printing method is shown to be attractive for the fabrication of pentacene thin-film transist...