Temperature-Dependent Spectroscopic Ellipsometry of Thin Polymer Films

Abstract

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.

Impact of bottlebrush chain architecture on Tg‐confinement and fragility‐confinement effects enabled by thermo‐cleavable bottlebrush polymers synthesized by radical coupling and atom transfer radical polymerization

“…In comparison with bulk films of the same polymer, thin films of linear, freely deposited polymers that are a few tens of nanometers thick may exhibit significantly different properties, for example, glass transition temperature ( T g ), fragility, and stiffness among others. [ 1–48 ] For instance, in comparison with a bulk polystyrene (PS) film and as measured by ellipsometry, a 21‐nm‐thick, substrate‐supported high molecular weight (MW) PS film exhibits a T g reduction of 10°C. [ 18 ] Understanding such nanoscale T g ‐confinement effects in polymers is important for many advanced technological applications, for example, thin films used in nanolithography processes for microchip manufacturing.…”

Strain–Microstructure–Optoelectronic Inter-Relationship toward Engineering Mechano-Optoelectronic Conjugated Polymer Thin Films

“…The glass transition temperature of P3HT samples has been determined by differential scanning calorimetry (DSC) [ 42 , 43 ]. Glass transition in P3HT thin films can be determined by monitoring changes in the polarization state (e.g., amplitude ratio and phase shift) or film thickness as a function of temperature using in-situ ellipsometry [ 44 , 45 ]. However, reported values of the glass transition temperature of P3HT vary substantially [ 43 , 45 , 46 , 47 , 48 , 49 ].…”

Towards Real-Time In-Situ Mid-Infrared Spectroscopic Ellipsometry in Polymer Processing

“…Further, reported contributions not only cover a wide range of polymer systems but also sophisticated analytical methods for the extraction of thermodynamic parameters [ 17 , 18 , 19 ]. The benefits of UV-VIS ellipsometric in-situ measurements were impressively demonstrated by evaluating dynamic processes, for example, the aging of polymer thin films monitored in a streamlined ellipsometry procedure and phase transitions in polymer thin films monitored by means of temperature-dependent spectroscopic ellipsometry [ 20 , 21 ]. However, since the UV-VIS is just sensitive to electronic states and excitons, measurements in the infrared spectral range (IR)—in which molecular vibrations, free-charge-carrier and phonon absorptions are probed—can provide valuable and diverse information.…”