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.