The ability to match two complementary polymers constitutes an important step forward in the design of electrochromic devices (ECDs). Here we show that the necessary control over the color, brightness, and environmental stability of an electrochromic window can be achieved through the careful design of anodically coloring polymers. For this purpose, we have constructed ECDs based on dimethyl substituted poly(3,4-propylenedioxythiophene) (PProDOT-Me 2 ) as a cathodically coloring layer, along with poly[3,6-bis(2-ethylenedioxythienyl)-N-methyl-carbazole] (PBEDOT-NMeCz) and N-propane sulfonated poly(3,4-propylenedioxypyrrole) (PProDOP-NPrS) as anodically coloring polymers. Comparison of the results shows that using PProDOP-NPrS as the high band gap polymer has several advantages over the carbazole counterpart. The main benefit is the opening of the transmissivity window throughout the entire visible spectrum by moving the π-π* transition of the neutral anodically coloring material into the ultraviolet region. Another advantage of the PProDOPNPrS based device is the noticeable increase in the optical contrast as evidenced by an increase in the transmittance change of the device (∆%T) from 56% to 68%, as measured at 580 nm. These devices exhibit a 60% change in luminance along with half-second switching times for full color change. Moreover, they were found to retain up to 86% of their optical response after 20 000 double potential steps, opening up new directions in optical technology.

A series of poly (3,4-alkylenedioxypyrrole)s are reported as a new class of electronically conducting polymers exhibiting especially low oxidation potentials from ca. -0.6 to -0.4 V vs Fc/Fc + (equivalent to -0.15 to +0.05 V vs SCE) as desired for ambient stability of the doped and conducting states. These polymers exhibit unique combinations of multicolor electrochromism, switching from a red or orange neutral state to a light blue/gray doped state, passing through a darker intermediate state (brown), as examined by in situ colorimetry. High spectral contrast ratios have been measured throughout the visible region with a maximum ∆%T ) 76% at 534 nm for poly[3,4-(2,2-dimethylpropylenedioxy)pyrrole) (PProDOP-(CH3)2). PProDOP-(CH3)2 exhibits outstanding redox switching stability, being able to undergo 40 000 deep double-potential switches between its doped and neutral states (1 s, ∆%Tmax ) 76%) while retaining more than 90% of its electroactivity. A high level of stability to overoxidation has also been observed as these materials show limited degradation of their electroactivity at potentials 2 V above their half-wave potential. Triflate-doped free-standing films of PEDOP and PProDOP, having high electrical conductivities of 83 and 95 S/cm, respectively, have been obtained by galvanostatic deposition at low temperature (-7 °C).

We report a colorimetric method for the in situ study of electrochromic polymers based on the CIE system of colorimetry. This method is useful for the comparison of the electrochemical and optical properties of conjugated polymers, and for gaining control of the color of dual polymer electrochromic devices. Twelve electrochromic polymers were investigated using in situ colorimetric analysis in order to define their CIE coordinates and electrochemical potential windows. By controlling the electron density and steric interactions along conjugated polymer backbones, we have developed a set of electrochromic polymers that provides colors throughout the full range of color space. The applicability of the method is illustrated with a model dual polymer device based on poly(2-(3,4-ethylenedioxy)thienyl(biphenyl)) (PBEDOT-BP) and poly(3,6-bis(3,4-ethylenedioxy)thienyl)-N-methylcarbazole) (PBEDOT-NMeCz). This device yields green/brown colors (L* = 48, a* = 0, b* = 20 and L* = 44, a* = 6, b* = 26) interesting for earthtone and natural vegetation chameleon materials when the charge states of the two polymers are reversed. This technique is a convenient method for reproducibly fine-tuning the color of electrochromic materials, while reducing trial and error in the process of electrochromic device development.

A series of electrochromic N-substituted poly(3,4-propylenedioxypyrrole)s (PProDOPs) are reported, which exhibit the combined properties of a high (>3 eV) electronic band gap, colored oxidatively doped forms, and easily accessible, low redox potentials. Utilizing methyl (Me), propyl (Pr), octyl (Oct), propanesulfonated (PrS), and ethoxyethoxyethanol (Gly) pendants, the absorbance of the π−π* transition of the resulting polymers is blue-shifted when compared to the nonderivatized parent. For example, in the case of poly(N-ethoxyethoxyethanol ProDOP) (N-Gly PProDOP), this transition displays a maximum at 306 nm (onset at 365 nm), providing a colorless and highly transparent neutral polymer with a luminous transmittance greater than 99% for a film thickness of about 200 nm. N-Substituted PProDOPs display very well-defined cyclic voltammograms, with E 1/2 < −0.1 V vs Fc/Fc+ (+0.2 V vs SCE), negative of the oxidation of water, as desired for materials having stable doped forms and long-lived redox switching properties. In addition, the presence of a sulfonate group at the end of the propyl chain in N-PrS PProDOP offers the possibility of self-doping along with water solubility of the polymer. As a result, N-PrS PProDOP exhibits a fast and regular growth even in the absence of supporting electrolyte. This new family of polymers has not only shown interesting electrochromic properties in the visible. Upon doping, a very strong absorption is observed in the near-infrared (NIR) with changes in transmittance up to 97%, extending the use of these polymers as the active layer in vis−NIR switchable devices.

A series of dual conducting polymer based type I supercapacitors were constructed using poly͑3,4-propylenedioxythiophene͒ and poly͑3,4-ethylenedioxythiophene͒ as electrode couples. The switching speeds and cycle lifetimes of these supercapacitors were compared using two types of supporting electrolytes; lithium bis͑trifluoromethanesulfonyl͒imide and 1-ethyl-3-methyl-1-Himidazolium bis͑trifluoromethanesulfonyl͒imide ͑a room temperature molten salt͒. The results indicate that supercapacitors using 1-ethyl-3-methyl-1-H-imidazolium bis͑trifluoromethanesulfonyl͒imide as the supporting electrolyte have cycle lifetimes superior to supercapacitors using lithium bis͑trifluoromethanesulfonyl͒imide as the supporting electrolyte.

A family of six donor-acceptor-donor monomers was synthesized using combinations of thiophene, 3,4-ethylenedioxythiophene and 3,4-ethylenedioxypyrrole as donor moieties, and cyanovinylene as the acceptor moiety, to understand the effects of modified donor ability on the optoelectronic and redox properties of the resulting electropolymerized materials. Spectroelectrochemistry, differential pulse voltammetry, and cyclic voltammetry results indicate band gaps ranging from 1.1 to 1.6 eV and suggest that these polymers can be both p-type and n-type doped at accessible potentials. In situ conductivity results indicate that the n-type conductivity magnitude is modest, and the conductivity profile indicates a redox conductivity mechanism as opposed to a delocalized electronic band mechanism as observed for p-type doping.

sulting mixture was stirred at room temperature for 12 h. From this mixture, polymer 7 was obtained as a bright yellow solid (1.20 g, 99 %) by suction filtration, followed by washing with a large volume of methanol and drying under vacuum at 50 C for 8 h. Anal. (calcd. Br± (C 17 Polymer 8: To a solution of polymer 7 (500 mg) in freshly distilled THF (50 mL) benzeneboronic acid (120 mg) was added and argon was bubbled through the mixture for 10 min. Pd(PPh 3 ) 4 (40 mg) and 1 M Na 2 CO 3 solution (2 mL) were added sequentially. The mixture was stirred and refluxed under argon for 90 h. THF was removed under vacuum and water (100 mL) was added to the flask. Suction filtration and washing with a large volume of water gave a light gray solid. The solid was dissolved in chloroform then filtered through Celite. The filtrate was precipitated in methanol followed by stirring for 24 h. Polymer 11: By analogy with the preparation and purification of polymer 7, 2,5-dibromo-4-hexylpyridine 6 (1.219 g, 3.797 mmol) and 2,5-dimethoxy-1,4-benzenediboronic acid 9 (0.857 g, 3.797 mmol) were polymerized to yield polymer 11 as a bright yellow solid (1.20 g, 90 % (m, 6 H, ±OMe); the aromatic proton signals have similar shapes to those of polymer 7, with five peaks at d 6.9, 7.3, 7.6, 8.0, and 8.6, with a total integral of 4.5 H.Polymer 12: By analogy with the preparation and purification of polymer 8, polymer 11 was treated with benzeneboronic acid (11.3 mg), Pd(PPh 3 ) 4 (2 mg), and 1 M Na 2 CO 3 solution (1 mL) in THF (10 mL) to yield polymer 12 as a light gray solid (85 mg Polymer 13: By analogy with the preparation of polymer 7, 2,5-dimethoxy-1,4-benzenediboronic acid 9 (0.565 g, 2.50 mmol) and 2,5-dibromopyridine (0.592 g, 2.50 mmol) were polymerized to yield polymer 13 (0.50 g, 94 %). Due to the low solubility of the polymer in ordinary organic solvents, further purification was not possible, apart from washing the solid with large volumes of water and methanol. Anal. (calcd. Br±(C 13 H 11 NO 2 ) 5 ± Br) C 63.03 (63.77), H 4.41 (4.53), N 4.67 (5.72), Br 11.17 (12.90). The polymer was essentially insoluble in standard NMR solvents, so no NMR data were recorded.Polymer 16: By analogy with the preparation of polymer 7, 1,4-benzenediboronic acid (0.416 g, 2.509 mmol) and the ditriflate 15 (1.150 g, 2.509 mmol) were polymerized to yield polymer 16 as a pale brown solid (0.41 g, 69 %). Attempted purification of the polymer involved dissolving the crude solid in hot o-dichlorobenzene and filtering through Celite under vacuum, then precipitating the polymer with ethanol, followed by suction filtration and washing the precipitate with a large volume of ethanol, and drying for 8 h at 50 C under vacuum.

No abstract