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.