Surface-induced alignment of pentacene by photo-alignment technology for organic thin film transistors

A series of highly soluble maleimide-based polymers with photoreactive pendant group were synthesized and used as a gate dielectric insulator for organic thin film transistors. Photoalignment properties were characterized by UV-visible spectroscopy and the alignment of liquid crystals. Photopolymerization of polymer-coated organic thin film transistors with linearly polarized UV light induces anisotropy in field-effect mobility. The gate dielectric insulator based on the photoalignable maleimide shows higher field-effect mobility and on/off current ratio than those from a SiO2 gate dielectric insulator with the values of 0.3 cm2 V−1 s−1 and 104, respectively. Our results demonstrate that the photo-induced anisotropy of alignment films to control the molecular order of semiconducting pentacene is a promising technology for improving the performance of organic thin film transistors.