An Orientation‐Controlled Pentacene Film Aligned by Photoaligned Polyimide for Organic Thin‐Film Transistor Applications

Abstract We have demonstrated that the photoalignment method could be used to control the structural anisotropy of pentacene films, an active semiconducting layer, in thin‐film transistors (TFTs) with conspicuously anisotropic electrical characteristics. The photoaligned pentacene films were characterized with respect to structure and morphology using X‐ray diffraction and atomic force microscopy. Compared to the pentacene films that are not controlled, a maximal 25‐times increase in field‐effect mobility (up to 0.75 cm V^–1 s^–1) has been achieved in the photoaligned pentacene‐based TFTs by aligning pentacene orientation parallel to the direction of current flow with the help of a photoaligned polyimide layer. Mobility anisotropic ratio in the range of 2.7–8.3 for the current flow parallel and perpendicular to the alignment of the photoaligned pentacene films have been observed for photoaligned pentacene‐based TFTs.