T. Gao, B.P. Jelle
Norwegian University of Science and Technology,
Keywords: electrochromic material, nanomaterial, smart window, energy efficiency
Summary:Abstract By actively regulating the solar radiation (both visible and near infrared part) passing through the window aperture, electrochromic (EC) smart windows can improve both the energy efficiency and the user comfort of windows. Thus, these EC windows show a promising potential in energy efficient buildings [1, 2]. However, the success of EC windows in the building sector will depend on not only the potential benefit that will be realized by the end user, but also a sophisticated design and selection of materials (e.g., EC materials, transparent conductive coatings, and ionic conductors) to make the EC windows durable and affordable. The recent development has shown that high performance EC devices can be achieved by using nanostructured EC materials and/or nanoassemblies, hence denoted hereafter as nanoelectrochromics [3-6]. The application of nanoelectrochromics usually leads to high coloration efficiency, high color contrast, and fast switching, which are important properties for EC windows. Obviously, a combination of size, morphology, and composition at nanometer scale will lead to a myriad of possibilities towards high performance EC devices, whereas it may also result in complexities and uncertainties with respect to mechanism, stability, durability, and so on. Therefore, systemic studies on nanoelectrochromics will still be essential. In this study, challenges and opportunities of nanoelectrochromics for large-area and large-scale window applications have been discussed. References  Baetens, R.; Jelle, B.P. and Gustavsen, A. (2010): Properties, requirements and possibilities of smart windows for dynamic daylight and solar energy control in buildings: A state-of-the-art review. Solar Energy Materials and Solar Cells, 94, 87–105.  Jelle, B. P. and Gao, T. (2015): The utilization of electrochromic materials for smart window applications in energy-efficient buildings. Proceedings of TechConnect World Innovation Conference 2015, Washington DC, USA, pp. 226–229.  Gao, T.; Gustavsen, A. and Jelle, B.P. (2010): Nanoelectrochromics with applied materials and methodologies. Zero Emission Buildings – Proceedings of the Renewable Energy Research Conference, Trondheim, Norway, pp. 61–71. [4 Gao, T. and Jelle, B. P. (2013): Paraotwayite-type α-Ni(OH)2 nanowires: Structural, optical and electrochemical properties. Journal of Physical Chemistry C, 117, 17294–17302.  Gao, T. and Jelle, B. P. (2013): Visible-light driven photochromism of hexagonal sodium tungsten bronze nanorods. Journal of Physical Chemistry C, 117, 13753–13761.  Gao, T.; Jelle, B. P. and Gustavsen, A. (2013): Synthesis and characterization of sodium tungsten bronze nanorods for electrochromic smart window applications. Proceedings of the 13th IEEE International Conference on Nanotechnology, Beijing, China, pp. 1093–1096.