Multilayer thin film structures for multifunctional glass: Self-cleaning, antireflective and energy-saving properties

In recent years, the search for sustainable development and environmental comfort has fueled exponential growth in the demand of smart glass for several applications including building and car windows, facades, computer displays, health care. Smart windows are meant to progressively replace traditional windows, considered as a less energy-efficient building envelope with a larger maintenance requirement. In this context, glass functionalization by multilayer coatings has received considerable research interest because of the potential to adjust glass properties to specific performance requirements. This review firstly reports on the main deposition methods and characterization strategies for multilayer coatings on glass. Then, the basic principles of antireflection, self-cleaning and energy efficiency are briefly discussed from the perspective of the functionalized glass. For each application, advances in multilayer structures are reviewed in detail, highlighting the reasons behind the choice of the wide range of materials forming the stratified layers of the coatings. Finally, the challenges and prospects for future development are discussed to help overcome existing limitations. This review shows how multilayer structures are the preferred choice for advanced glazing systems. They can rely on the synergic interaction between different films, able to ensure a multifunctional character, thus offering a clear added value over the traditional single-layer configuration. It is hoped that this review will support a better awareness of the advantages of using multilayer coatings, which will contribute to finding new pathways to the design of increasingly efficient smart glass.