Self-Organization Characteristics of Soluble Pentacene on Wettability-Controlled Patterned Substrate for Organic Field-Effect Transistors

Solution-processed self-patterning of 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS_PEN) has been achieved by wettability control on a dielectric surface. This is useful for the fabrication of arrayed patterns due to the exactness and simplicity of the patterns. Especially, we systematically studied the dependence of the self-organization behavior of soluble TIPS_PEN on pattern size and solvent evaporation rate using a circular geometry. With fast evaporation rates during solution-casting, the patterned deposits developed a low degree of crystalline microstructure and ringlike morphological (coffee-staining) structures, which were induced when evaporation-driven flow in a solution droplet was dominant. In contrast, long evaporation times produced TIPS_PEN deposits with well-ordered crystalline and dotlike morphological structures resulting from dominant diffusion-driven flow. Solvents with moderate evaporation rates allowed control over the conditions in which the morphological and crystalline structures of the semiconductor deposit formed, producing enhanced control over the electrical performance of organic field-effect transistors.