Electrochromic window

Jelle and Hagen have recently developed an electrochromic window for solar... 

Figure 1.36 Cross section through an electrochromic window.

Metal-oxide-based electrochromic systems are especially interesting for the development of electrochromic windows because they mostly switch from a transparent state to a dark colored state [38,39]. In addition, their relatively slow response times are acceptable for this kind of application, possibly even preferable from an aesthetic point of view. Again, W03 has seen the most use in the development of actual devices. Several different deposition techniques have been applied. For example, a prototype electrochromic window based on W03 with reasonable dimensions (0.7 X 1 m) has been assembled that reduces light transmission by a factor of 4 in its colored state [28]. 

Figure 6.38 Electron flow diagram of the switching processes that take place for an electrochromic window based on viologen/Ti02 and phenothiazine/Sn02-Sb modified electrodes. Reprinted with permission from D. Cummins, G. Boschloo, M. Ryan, D. Corr, S. N. Rao and D. Fitzmaurice, /. Phys. Chem., B, 104, 11449 (2000). Copyright (2000) American Chemical Society...

Optical quality thin films of metallic polymers are useful, therefore, as transparent electrodes [68]. For example, polyaniline [69], polypyrrole [70] and PEDOT [71] have been used as transparent hole-injecting electrodes in polymer LEDs (the initial demonstration of mechanically flexible polymer LEDs utilized PANl as the anode [69]). Transparent conducting films can be used for a variety of purposes for example, as antistatic coatings on CRT screens, as electrodes in liquid crystal display cells, or for fabricating electrochromic windows. 

R. Cinnsealach G. Boschloo S. N. Rao D. Fitzmaurice, Colored electrochromic windows based on nanostructured Ti02 films modified by adsorbed redox chromophores. Sol. Energy Mater. Sol. Cells 1999, 57, 107-125. 

Polarization cell Measurement of kinetic data by polarization Electrochemical composition actors (electrolyzers, pumps, electrochromic windows), electrochemical composition sensors (amperometric, conductometric)... 

High-resolution circuitry and active devices employing Langmuir-Blodgett film techniques or polymer-based transistors are being considered for the sophisticated electronics required in future vehicles. Temperature or energy balance in the vehicle could be controlled through conductive polymers or semiconductor deposits on electrochromic windows. Electroluminescent liquid crystals and fluorescent and electrochromic materials used for visual displays show promise for future development. 

Figure 14.39 Schematic drawing of a PANI/PAMPS/WO3 electrochromic window. Reprinted from ref 96 with kind permission from Elsevier Science Ltd.

Many electrochemically dopant-induced structure-property changes in conducting polymers have been described for use in, for example, electrochromic windows and displays, electrochemically controlled chemical separation and delivery systems, redox capacitors, electromechanical actuators, etc.,32. Some of these are apparently close to commercial application. Polypyrrole capacitors are already in conunercial production,27. 

As naturally abundant and low-cost semiconductor, NiO is widely used in electrochromic windows [20], batteries [21], supercapacitors [22], and sensors [23], While all these applications benefit from an interconnected, three-dimensional NiO nanostructure that combines a high specific surface area with a good electric conductivity, the performance enhancement becomes vividly evident as an increased coloration contrast and improved switching behavior when applied in electrochromic devices. NiO nanomaterials recently employed in electrochromic studies include nanocomposites [24], inverse opals [25], macroporous [26] and mesoporous films [27-29],... 

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