Thermo-optical properties of conducted polythiophene polymer films used in electroluminescent devices

In this paper we present results of ellipsometric studies of thin organic poly-3hexylthiophene–(P3HT) and poly-3octylthiophene ( P3OT) films performed in temperature range 20–300 °C. The optical dispersion spectra of refractive and extinction indices of presented organic films was determined in wavelength range 190–1700 nm for temperatures within in a given range. Also thermo-ellipsometric investigations allowed to find temperature dependence on film thickness. The determination of thermal changes of thickness and refractive index allowed us to calculate thermo-optical coefficients (TOC) for P3HT and P3OT layers for many wavelengths in measured spectral range. The obtained values of thermo-optical coefficients of thin P3HT layers, determined from combined ellipsometric and spectro-photometric investigations, are negative in visible part of spectral range of the order of 10 −4 [1/K] .