Thermochromic composite coatings show unrivalled optical properties

Brightlands Materials Center is developing innovative thermochromic coatings for energy-efficient smart windows. Within lab scale research activities ground breaking new results have been achieved. Cindy Yeung is reporting in her first scientific publication about this break through in the Journal Solar Energy Materials and Solar Cells.

Solution processed single layer coatings

The break through was achieved via solution processed single layer coatings on float glass based on vanadium dioxide as functional material. By carefully integrating the material in the correct crystal structure in a silica matrix, Yeung and colleagues realized a combination of visible transmission above 60% with a solar modulation of over 10% for a coated glass plate. Such high thermochromic performance has only been achieved at much lower transparency in previous studies.

Additional impact of coating matrix

Furthermore, the coating matrix could be used to increase the stability and robustness of the thermochromic VO2 coating. Yeung and colleagues were able to prepare non-scattering coatings with low surface roughness which exceed the scratch resistance of regular energy-efficient window coatings. Additionally, due to the matrix the coatings are robust and stable for up to one year under atmospheric conditions and for more than 10 years within an insulating glass unit, which is essential both for processing of the coated glass plates and for application in smart windows.

Positive impact on energy savings in the Netherlands

For thermochromic smart windows a high visible transmission in combination with high solar modulation is essential for the performance in smart windows. Only this combination allows maximum energy savings for both heating in winter and cooling in summer via an optimized use of solar heat. Yeung and colleagues have shown via building energy simulations that the new hybrid coating can yield up to 24% energy savings for building operations, when applied as smart window in a regular Dutch building.

Interested in the scientific article and the research activities within Brightlands Materials Center? Contact Eugene Veerkamp or read the publication.