  The thermal deposition and transfer Printing method had been used to produce
pentacene thin-films on SiO2/Si and plastic substrates (PMMA and PVP),
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 15.4 A.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 15.4 A phase towards 14.4 A phase was also observed with
increasing film thickness. An increase in the c-axis correlation length of
approximately 12% ~16% was observed for Pn films transfer printed onto a PMMA
coated PET substrate at 100~120 C as compared to as-grown Pn films on SiO2/Si
substrates. The transfer printing method is shown to be an attractive for the
fabrication of pentacene thin-film transistors on flexible substrates partly
because of the resulting improvement in the quality of the pentacene film.
