Fabrication of Large-scale Drop-cast Films of π-conjugated Polymers with Floating-film Transfer Method

Abstract

Large-scale drop-cast films of π-conjugated polymers such as polythiophene derivatives and polyfluorene-based copolymers have been formed on a liquid-substrate with one-step deposition of Floating-film Transfer Method (FTM). Centimeter-scale uniform cast films could be obtained. Relative sharp vibronic structure was found in the Absorption spectra of FTM films as compared to those in spin-coated ones. FTM provides concentrically oriented films of a polymer having thermotropic liquid crystal characteristics. Comparative study of AFM topography with absorption spectra revealed that the origin of the optical anisotropic absorption was in the uniaxial orientation of nano-scale fibrils. This indicates that the oriented FTM films possess extremely large domains extended over 5 orders from micrometer to 10 centimeter scale. The findings represent that FTM is a simple and effective casting method to provide large-scale and uniform drop-cast films.