Electrochromic device, definition

All the electrochromic performance parameters cited earlier in Chapter 3 are valid equally for electrochromic devices as for laboratory-cell electrochromic systems Dynamic range switching time cyclability open circuit memory. The reader is referred to this chapter for further reference and definitions. 

Akhtar et al. [902(a)] were one of the first to describe completely assembled, sealed, solid-state electrochromic devices based on CPs. In one set of devices, the fairly common Li-triflate/Poly(ethylene oxide) (PEO)/acetonitrile formulation for nonaqueous solid electrolytes was used. However, in another set, the unique combination of poly(ethyleneimines) of different MWt and protonic acids such as hydrochloric, sulfuric, phosphoric, acetic and poly(styrene sulfonic) was used. Additionally, the films of the CP, P(ANi), were prepared electrochemically as well as by sublimation, and in one set of devices Fe-tungstate was used as a counter electrode to provide a definitive counter electrode reaction (Lithiation). While cyclabilities to several thousand cycles were claimed, the electrochromic dynamic range and other parameters were fairly poor, as seen in Figs. 20-3. Very rapid switching times have been claimed for many P(ANi)- or P(ANi)-derivative based devices. For example. Ram et al. [902(b)] claimed a 143 ms switching time for liquid-electrolyte devices based on poly(aniline-co-o-anisidine). 

Electrochromism is the reversible change in optical properties that occurs when a material is electrochemically oxidized or reduced [224], This working definition includes a change in optical properties anywhere in the solar (and even in some cases the microwave) range. In addition to the active electrochromic layer, a device consists of an electrolyte and a counter electrode, which may or may not be electrochromic. The electrolyte should be a good ionic conductor and electrically insulating in order to be nonvolatile. 

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