Determination of the optical constants of a vacuum evaporated polythiophene thin film

This paper reports the optical properties of polythiophene thin films prepared by a vacuum evaporation technique on a glass substrate. The structural properties, surface morphology and wettability of the thin films were studied. Polythiophene thin films show a porous surface morphology and a hydrophobic nature. The refractive index and extinction coefficient of these thin films were studied by using the well-known envelope method from the transmittance spectra. The transmittance and extinction coefficient increase with an increase in wavelength, whereas the refractive index decreases in the visible region and remains nearly constant in the infrared region. The calculated optical band of the polythiophene thin film is 2.75 eV.