Behavior of pentacene molecules deposited onto roughness-controlled polymer dielectrics films and its effect on FET performance

We describe the effects of the polymer dielectric surface roughness on the nucleation and initial island growth of pentacene films in the submonolayer regime using poly(methylmethacrylate) and polystyrene films with highly controlled surface roughness value. The pentacene film structures were found to significantly affect the performances of pentacene field-effect transistors (FETs). As the dielectric surface roughness increased, the activation energies for pentacene island nucleation and molecule reevaporation from the surface were dramatically reduced. A high surface roughness greater than 0.9 nm was found to limit the degree to which the FET performances could be improved. These results suggest a means for optimizing the nanostructural surfaces of polymer dielectrics by engineering OFET interfaces in an effort to improve device performance.