Thin polymer films have found many important applications in organic electronics, such as active layers, protective layers, or antistatic layers. Among the various experimental methods suitable for studying the thermo-optical properties of thin polymer films, temperature-dependent spectroscopic ellipsometry plays a special role as a nondestructive and very sensitive optical technique. In this Review Article, issues related to the physical origin of the dependence of ellipsometric angles on temperature are surveyed. In addition, the Review Article discusses the use of temperature-dependent spectroscopic ellipsometry for studying phase transitions in thin polymer films. The benefits of studying thermal transitions using different cooling/heating speeds are also discussed. Furthermore, it is shown how the analysis and modeling of raw ellipsometric data can be used to determine the thermal properties of thin polymer films.

The article presents the thermal and physical properties of PMMA composite films with the addition of Nb₂O₅ nanoparticles. The addition of nanoparticles to PMMA mainly influenced the optical transmission and glass transition temperature of composite films compared to pure PMMA. It is clearly visible in the results of the conducted ellipsometric and differential scanning calorimetry tests. X-ray studies showed that the heat treatment of the samples resulted in the ordering of the polymer structure (flattening of the polymer chains). Examining the surface of the samples with scanning electron microscopy, it can be seen that Nb₂O₅ nanoparticles formed unusual, branched formations resembling "snowflakes".

The important research direction in surface engineering and photovoltaics is the development of new materials that can replace the previously used expensive films. A prospective compound is zinc oxide (ZnO), characterized by optical and electrical properties similar to ITO and a lower production cost. One of the key factors influencing the properties of the ZnO thin films is the technique and parameters of their production. The comprehensive investigation results of the influence of ZnO thin-films deposition process temperature on their structure, optical properties, and adhesion are presented in the paper. ZnO films were deposited by the magnetron sputtering method. The structural characteristics of the tested films were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray diffractometry (XRD) and Raman spectroscopy, while the optical properties of the films were studied by the UV/VIS spectroscopy. Thickness and adhesion measurements of the obtained films were performed using the spectroscopic ellipsometry technique and the scratch test, respectively. The obtained research results showed the influence of the deposition process temperature on the morphology, crystallite size and adhesion of the thin films to the substrate. The effect of process temperature on optical properties, the value of the optical bandgap and crystal structures were analyzed and described. The results of this work have a meaning for the development of surface engineering and may serve as a clue in future studies in the field of modern photovoltaic structures.

In this work we present an in-depth study of the how the composition of poly(3-hexylthiophene) (P3HT):[6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) blend films influences their phase transitions using variable-temperature spectroscopic ellipsometry. We demonstrate that this non-destructive method is a very sensitive optical technique to investigate the phase transitions and to determine the glass transition temperatures and melting crystallization points of the P3HT:PCBM blend films. By analyzing the influence of the temperature T on the raw ellipsometric data, we have identified a high sensitivity of the ellipsometric angle Δ at a wavelength of 280 nm to temperature changes. Characteristic temperatures determined from the slope changes of the Δ(T) plot appeared to be very good guess values for the phase transition temperatures.

The aim of this study was to produce nanocomposite polymer fibres, consisting of a matrix of polyacrylonitrile (PAN) and a reinforcing phase in the form of SiO₂/TiO₂/Bi₂O₃nanoparticles, by electrospinning the solution. The effect of the nanoparticles and the electrospinning process parameters on the morphology and physical properties of the obtained composite nanofibres was then examined. The morphology of the fibres and the dispersion of nanoparticles in their volume were examined using scanning electron microscopy (SEM). All of the physical properties, which included the band gap width, dielectric constant and refractive index, were tested and plotted against the concentration by weight of the used reinforcing phase, which was as follows: 0%, 4%, 8% and 12% for each type of nanoparticles. The width of the band gap was determined on the basis of the absorption spectra of radiation (UV–vis) and ellipsometry methods. Spectroscopic ellipsometry has been used in order to determine the dielectric constant, refractive index and the thickness of the obtained fibrous mats.