Photo-assisted molecular engineering in solution-processed organic thin-film transistors with a blended semiconductor for high mobility anisotropy

This paper reports a viable method for enhancing mobility anisotropy in solution-processed organic thin-film transistors (TFTs) by irradiating linearly polarized ultraviolet (LPUV) light onto a 6,13-bis(triisopropylsilylethynyl)- pentacene (TIPS-pentacene)/poly (vinyl cinnamate) (PVCi) blended semiconductor film. The needle-like crystalline domains in the blended semiconductor film were aligned along the polarization direction of the LPUV light, suggesting that TIPS-pentacene molecules are oriented anisotropically due to an intermolecular interaction and aggregation with the photo-aligned PVCi molecules. The mobility anisotropy reached up to about 50, which is the highest value achieved in solution-processed organic TFTs with a polymeric insulator.