Thermochromic Materials for Solar Degradation Resistance and Energy Efficiency

Thermochromic materials (TCMs) possess reversible color changes with respect to the variation of temperature. TCMs have two apparent phases: a light phase upon heating, reflecting more radiation, and a dark phase upon cooling, absorbing more radiation. Their color change properties can be used to vary the throughput of visible light and solar energy for applications in windows and building surfaces. However, due to being partly organic, when exposed to sunlight with a wide range of wavelengths from UV to near IR, TCMs often degrade. This degradation limits TCM’s potential applications, such as coating building exteriors and energy storage. As the TCMs degrade, there’s an observable change in both phases, gradually becoming less distinct and effective as separate light and dark phases. Microencapsulation of TCMs by inorganic metal oxides, such as TiO₂, can potentially prevent this degradation. This project aims to develop a combined solar simulator and environmentally controlled chamber to obtain realistic TCM degradation data and its dependence on irradiation wavelength and environmental conditions like ambient temperature or humidity. Under conditions, data points will be tracked throughout the degradation by characterizing both phases before and after exposure for each testing cycle in the apparatus. The data presented focuses on the degradation of metal oxide encapsulated and pristine TCMs with various optical filters and the associated techniques, instrumentation, and characterization.