Melt Molding of Uniaxially-Oriented Crystal Domains onto a Substrate

Abstract

We have fabricated semiconducting oligomer films composed of uniaxially-oriented crystal domains by melt molding. It is highly important to generate a temperature gradient in the lateral direction parallel to the substrate on which the said oligomer films are fabricated. As a result, the melted oligomer layer starts to solidify from parts of lower temperatures to end up as a uniaxially aligned film. The uniaxial alignment is further promoted by slowly cooling that oligomer layer. In the present studies, the temperature gradient was set at ∼0.06–0.4 °C/mm. From the polarizing microscope observations, we confirm that within this range the temperature gradient efficiently produces the uniaxial orientation. This method has been applied to fabricating organic field-effect transistors. Those devices show an effective modulation of the drain current with varying gate voltage.