Examples of Actual, Functional Devices

We may now briefly discuss some studies of actual, fully fabricated, CP-based electrochromic devices. 

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). 

20-4 Electrochromic data for solid state P(ANi) device. After Refer- 

Several devices incorporating P(ANi) as a dispersion in a polymer matrix have been described [908]. Several reflectance-mode devices incorporating CPs have also been described, some even including such environmentally unstable CPs as poly (acetylene) and reductively coloring ones such as poly(isothianaphthene) [909-911]. Nissan Motor Co. and several other manufacturers have described electrochromic devices capable of being incorporated into automobiles in rear view mirrors, displays, or windshields [912]. 

In early work, Corradini et al. [913] described ca. 2 cm X 1 cm devices based on P(3MT) in which the liquid electrolyte (2 mm thickness) was LiC104/PC and the counter electrode reaction wa presumed to involve Li ion insertion. Charge capacities of ca. 7.5 mC/cm were reported. Arbizzani et al. [914] described a similar device, with Li ion insertion into Li/NiO/ITO as the counter electrode reaction. Color changes of purple to very pale blue were claimed. Fig. 20-6 fa.bl show, respectively, the spectroelectrochemical characterization of one of their devices and its chronovoltabsorptometry at 530 nm. 

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