Electrochromic folis for energy efficient buildings: Test methodology based on impedance spectroscopy

Time period: 2008-07-01 to 2010-12-31

Project leader: Gunnar Niklasson

Other personnel: Claes-Gö Granqvist, Claes-Göran Granqvist, Peter Georen

Funder: Formas

Type of award: Unclassified

Total fundning: 1 903 000 SEK

This application regards development of electrochromic (EC) foil for uses in windows and glass façades. Research and development will be based at Uppsala University (UU) and will be conducted in close collaboration with ChromoGenics AB (ChG); this company co-finances the project by its own work. Research on EC materials and devices has been carried out at UU for a number of years, and has led to a novel concept, namely EC devices based on coated polymer foils laminated by a polymer electrolyte. In order for the EC technology to be of practical interest, it is a must that it is durable at least for several years, which leads to a need for reliable techniques to assess what happens during natural and accelerated ageing. Impedance spectroscopy (IS) is an established method for this, which makes it possible to document even minor changes. It also, via circuit models, opens possibilities to interpret changes in physical and chemical properties of the device and hence pinpoint the source of the degradation. The goal of this application thus is to introduce IS as an industrially viable testing technique for developing a durable EC foil. Ultimately this research will contribute to the establishment of this foil as a new Swedish environmental technology.