Multiply Colored Electrochromic Carbazole-Based Polymers

Abstract

We report the synthesis and electrochemical polymerization of a series of bisheterocycle-N-substituted carbazoles. These monomers exhibit low peak oxidation potentials (E p,m ) which range from 0.15 to 0.46 V vs Ag/Ag + , indicating facile polymerization. Repeated scan electrochemical polymerization for these monomers proceeds rapidly, relative to carbazole, to form stable electroactive films. Cyclic voltammetry of the polymers indicates that the films are well adhered to the electrode surface and that each of the polymers possess two distinct redox waves. At applied potentials greater than 1.15 V, a third irreversible oxidative process is observed, presumedly due to cross-linking. Optoelectrochemical analysis indicates that these polymers have an electronic bandgap (measured as the onset of the π-to-π* transition) between 2.4 and 2.5 eV. Three distinct colors are achievable by varying the redox state of the polymers suggesting potential use for multiply colored electrochromic displays. For the series of bis(ethylenedioxythiophene)-N-substituted carbazoles, the fully reduced form of the polymers are canary yellow. Upon mild oxidation, the films become green and in the fully oxidized form, blue.

Carbazole electrochemistry: a short review

“…For 3,6-disubstituted compounds, coupling can occur with an external aromatic via oxidation. This situation was reported by Sotzing et al for 3,6-bisheterocycle-N-substituted carbazoles [35]. The authors performed oxidative polymerization, which proceeds through the alpha-positions of the external heterocyclic rings, since the 3-, 6-, and 9-positions of the carbazole are blocked.…”

“…The authors performed oxidative polymerization, which proceeds through the alpha-positions of the external heterocyclic rings, since the 3-, 6-, and 9-positions of the carbazole are blocked. Moreover, in this case, the external rings exhibit high electron density, and oxidation occurs at quite low potentials-even lower than the potential for the oxidation of carbazole [35]. Fig.…”

Electrochromic organic and polymeric materials for display applications

“…Using a series of oxidatively polymerizable bisarylene EDOT monomers (figure 9), polymers with bandgaps ranging from 1.4 -2.5 eV have been prepared that exhibit two to three distinct colored states. 75,76,[95][96][97] FIGURE 9…”

Electrochemistry of Poly(3,4‐alkylenedioxythiophene) Derivatives

“…[54] cyanovinylene 26, [55] ethynylene 27, [56] furan 28 and thiophene 29, [57] bithiophene 30 and 5,5¢-bisvinylene-bithiophene 31, [58] benzene 32 and biphenyl 33, [57] dialkoxybenzenes 34, [59] pyridine 35 and bipyridine 36, [60,61] carbazoles 37, [57,62,63] fluorenes 38, [64] sillole 39, [65] benzothiadiazole 40, [66] and tetrathiafulvene 41.…”