Aline ROUGIER

Abstract:

Smart materials are the salient feature of our modern e-connected society. Among them, optical materials are continuously evolving and finding more areas of application, such as the electrochromic windows in the Boeing 787 Dreamliner and Gentex Corporation’s antiglare mirrors. Electrochromic smart windows can be used in cars or buildings to adjust brightness or in spacecraft to moderate the intense thermal fluctuations by switching between light/infrared transmission and reflection. Electrochromic materials and devices change their optical properties in a reversible and persistent way under an applied voltage¹. The most frequently used electrochromic compounds include transition metal oxides, such as WO₃, MoO₃, TiO₂, IrO₂, V₂O₅, NiO, Prussian blue (iron ferrocyanide) analogues and organic polymers, such as polyaniline, polypyrrole, and polythiophen. Inorganic electrochromic materials are stable and WO₃ is central to most applications, however their range of available colors and brightness are limited. On the contrary, organic polymers show high color efficiency and a huge range of colors but suffer from limited stability-particularly when exposed to the ambient environment.
Aiming at improving EC properties for displays applications, our approach combines hybrid materials and novel design for ambient air and room temperature fabrication. In this presentation, focusing in particular on enlarging the palette of color, the advantage of mixing oxides and polymers will be demonstrated. As an example, the addition of iron oxide on poly(3,4-ethylenedioxythiophen), allows to switch not only from light to deep blue but also from blue to red². An additional step towards multichromism can be achieved by using vanadium oxides based devices reaching color modulation from orange to green and blue³.
Acknowledments : This activity included in the SUPERSMART project has received funding from the European Institute of Innovation and Technology (EIT). This body of the European Union receives support from the European Union’s Horizon 2020 research and innovation program.

[1] C. G. Granqvist, Handbook of Inorganic Materials, 1995.
[2] D. Levasseur, I. Mjejri, T. Rolland, A. Rougier, Polymers 11(1) (2019) 179.
[3] I. Mjejri, M. Gaudon, G. Song, C. Labrugère, A . Rougier ACS Applied Energy Materials, 1(6) (2018) 2721-2729.