Electrochromic polymers spectroelectrochemical

Pelous, Y., G. Froyer, D. Ades, C. Chevrot, and A. Siove. 1990. Spectroelectrochemical studies of electrochromic poly(JV-butyl-3,6-carbazolediyl) films. Polym Commun 31 341-342. 

Desbene-Monvemay, A., P.C. Lacaze, J.E. DuBois, and P.L. Desbene. 1983. Polymer-modified electrodes as electrochromic material. Part IV. Spectroelectrochemical properties of poly-N-vinyl-carbazole films. / Electroanal Chem 152 87-96. 

We describe die moiphologicai, electrochemical, spectroelectrochemical characterization, and electrochromic device properties of several polymer films ladder poly(benzobisiniidazobenzophenandiroline) (BBL),... 

We report here morphological, electrochemical and spectroelectrochemical studies of semiladder poly(benzobisimidazobenzophenanthroline) (BBB), ladder poly(benzobisimidazobenzophenanthroline) (BBL) and poly(2,2 -[10-mediyl-3,7-phcnothiazylene]-6,6 -bis[4-phenylquinoline]) (PPTZPQ) e structures are shown in Figure 2. We also describe the construction and characterization of die electro-optical properties of all-polymer electrochromic devices using PPTZPQ as one electrode and BBL, BBB or V2O5 as die counter electrode. 

Spectroelectrochemical analyses of the BBB, BBL, and PPTZPQ polymer films were performed to study the electronic structure and to examine the spectral changes that occur during redox switching both are inportant for electrochromic applications. BBL spectra showed an increase in absorbance at 524 nm, a decrease at 583 nm, and two not well-defined isosbestic points at 375 and 550 nm BBB spectra did not show clear isosbestic points. For die reduced form of BBB, the maximum peak was at 503 nm, and as die lied potential passed over the first voltammetric feature, the film exhibited an absorption peak at 576 nm These electrochromic effects were stable and reversible under anaerobic and anhydrous conditions die BBL and BBB films continued to exhibit strong color changes after more dian 500 successive cycles in MeCN (24). 

The simplest spectroelectrochemical measurement which yields information on electrochromic properties of CPs is the UV-Vis-NIR spectroelectrochemical curve, an in-situ or sometimes ex-situ measurement of the transmission-mode UV-Vis-NIR spectrum of the CP at various applied potentials. Such a measurement, which we shall hereinafter abbreviate as a SPEL curve (or just SPEL), is depicted in Fig. 3-1 this figure is a re-representation of the optical spectra of poly(pyrrole) (P(Py)) discussed in Chapter 2, with an abscissa in terms of wavelength, and represents a particularly well-behaved CP system. To recap again here, the single, prominent valence conduction (tt tt ) band transition in the pristine polymer (at ca. 388 nm) is accompanied by three additional polaron based transitions at low doping level (ca. 590 nm, 885 nm, 1,771 nm), which finally evolve into two bipolaron based bands (ca. 459 nm, 1,240 nm). 

Demonstrating that these low oxidation potential aromatic amines are very easy to polymerize, the Dao group subsequently reported [410] chemical polymerization with Cu(Bp4)2 xH20 oxidant/dopant for a series of Poly(N-alkyl-Diphenylamine) s. A 4-4 C-C (phenyl-phenyl) coupling mechanism was claimed for tWs polymerization. These CPs showed poor conductivities (10 S/cm) and a yellow-to-violet electrochromism. In a variant of diis syntliesis, Poly(N-alkyl-diaryl amines), i.e. with a naphthalene group replacing one of the phenyls in DPA, were chemically synthesized by Dao et al. [586]. These polymers however showed poor conductivity (10 S/cm) even in their highly doped form. The spectroelectrochemical characterization of these (see Chapter 3) showed broad-band responses characteristic of P(DPA) and its derivatives. 

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