The surface energy-dictated initial growth of a pentacene film on a polymeric adhesion layer for field-effect transistors

We describe how the surface energy of a polymeric adhesion layer affects the initial growth of a pentacene film for field-effect transistors (FETs). Three types of adhesion layers having different surface energies and morphologies were produced with varying the composition ratio of two different polyimides. For the pentacene film of 0.4 nm thick, the monolayer coverage of pentacene grains increases from 26.3% to 64.9% with increasing the surface energy of the underlying adhesion layer from 12.9 to 25.8 mJ/m2. The surface energy of the adhesion layer is found to play a more dominant role on the initial growth of a pentacene film than the surface roughness. The field-effect mobility in the pentacene FET depends strongly on the monolayer growth of pentacene grains.