Programmed Design of Highly Crystalline Organic Semiconductor Patterns with Uniaxial Alignment via Blade Coating for High-Performance Organic Field-Effect Transistors.

Abstract

A solution-printing technique that enables the patterning and aligning of organic semiconducting crystals is necessary for their practical application. Here, we report the facile growth of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-PEN) semiconducting crystal patterns via a novel blade-coating technique. Defining low/high shearing-speed regions alternatively in a programmed manner enables the growth of TIPS-PEN crystals in low-speed regions and their patterning in high-speed regions. Various crystal-analysis tools, including polarized UV-vis absorption spectroscopy, grazing-incidence wide-angle X-ray scattering, and near-edge X-ray absorption fine structure, reveal that a crystal grown at an optimum shearing speed is highly oriented along the shearing direction with high crystallinity, and its molecules have a more edge-on orientation for efficient lateral-charge transport. As a result, organic field-effect transistors comprised of these crystals show a high field-effect mobility of up to 1.74 cm2/(V s). In addition, various crystal patterns can be created by simply changing the programming parameters, suggesting the broad utility of the crystal patterns and printing technique.