Optically tailored nanovoid coatings

Kurzfassung

A Spanish public research organization has patented a new coating containing nanovoids of 1-50 nm (nano meters) diameters, whose manufacture control determines the refractive index, color, density, mechanical and other coating properties. The process is easy to implement at industrial scale. Main applications are tunable filters, reflectors and color coatings, heat accumulators and efficiency enhancer of solar cells. They are looking for partners for Licensing Agreement

Details

A Spanish Research organization has developed a new coating containing nanovoids. The Nanovoid coating process makes a specific use under controlled conditions of reactive magnetron sputtering technology to prepare tailored closed porosity coatings by controlling the gases composition, the sputtering power or the target distance.

The nanovoid (closed porosity) are formed directly during the film growth, therefore coatings are produced with no limit of thickness, even in the range of several microns. The microstructure is formed when the sputtering process is conducted in an atmosphere rich in gases like nitrogen or helium. This type of closed porosity modifies the refractive index of the deposited layers in a wide range of values, without a significant change in the chemical or mechanical stability of the deposited material. Therefore, manipulating the presence of such nanovoids specific microstructures can be produced, leading to the desired optical characteristics. Additionally, the conditions can be changed throughout the manufacturing process in order to create coatings consisting of different microstructured layers.

The manufacturing method is based on a fully operational technology easily implemented in the current processing lines in industrial scale.

This possibility opens the way to produce optical devices with accurate tailored characteristics.

Innovative Aspects:
• The main innovation provided by this system is the possibility of obtaining porous coatings with the peculiarity that the pores do not have an exit to the surface as those made so far. This peculiarity eliminates the limits of the layer thickness, which can be produced up to microns.
• The nanovoids fabricated can vary the coating refractive index within a wide range of values, without changing the chemical composition or mechanical and chemical stability.
• The procedure is based on the reactive magnetron sputtering technology, fully implemented in the industry, thus directly applicable to mass production.
• The procedure provides complete control over the coating microstructure, as well as a total homogeneity throughout the coating thickness. This redounds into a precise control of the optical and mechanical properties of the coating.