Two-step surface modification for bottom-contact structured pentacene thin-film transistors

Abstract

We investigated surface treatment effects of hexamethyldisilazane (HMDS), poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS) and l-cysteine on gold source/drain electrodes in bottom-contact structured pentacene thin-film transistors (TFTs). The treatment methods include spin coating and immersing. We have also researched on two-step treatment based on the combination of each treatment methods. The highest device performance was achieved by treating gold S/D electrodes with l-cysteine first and PEDOT:PSS afterwards, showing field effect mobility up to 0.35 cm2/V·s. l-cysteine can reduce the contact resistance between metal and semiconductor layer, and PEDOT:PSS acted as a hole transporting layer while HMDS decreased the surface energy, which enlarged the grain size of pentacene on it.