Anisotropic field-effect mobility of pentacene thin-film transistor: Effect of rubbed self-assembled monolayer

Enhanced and anisotropic field-effect mobility of thin-film transistors based on pentacene was obtained on a substrate covered with a prerubbed, self-assembled monolayer (SAM) of n-alkyltrichlorosilane. The field-effect mobility along the rubbing direction increased by a factor of ∼15 on rubbed n-nonyltrichlorosilane-modified surface, whereas on n-octadecyltrichlorosilane-modified surface, an increase by a factor of 2–4 was observed. The structures of pentacene films deposited on the SAM/rubbed SAM were characterized by powder x-ray diffraction, atomic force microscopy, and carbon K-edge near edge x-ray fine structure spectroscopy. An in-plane alignment effect on the pentacene packing and film morphology is proposed.