Electrochromism

About: Electrochromism is a research topic. Over the lifetime, 13097 publications have been published within this topic receiving 294637 citations.

Conjugated Polyelectrolyte Blends for Electrochromic and Electrochemical Transistor Devices

Abstract: Two self-doped conjugated polyelectrolytes, having semiconducting and metallic behaviors, respectively, have been blended from aqueous solutions in order to produce materials with enhanced optical and electrical properties. The intimate blend of two anionic conjugated polyelectrolytes combine the electrical and optical properties of these, and can be tuned by blend stoichiometry. In situ conductance measurements have been done during doping of the blends, while UV–vis and EPR spectroelectrochemistry allowed the study of the nature of the involved redox species. We have constructed an accumulation/depletion mode organic electrochemical transistor whose characteristics can be tuned by balancing the stoichiometry of the active material.

Complementary hybrid electrodes for high contrast electrochromic devices with fast response.

Abstract: Fast switching ‘transparent-to-black’ electrochromic devices are currently under investigation as potential candidates in modern applications like e-papers or with additional functionality as ultracompact iris or switchable neutral filter in camera systems. However, recent electrochromic devices show either a lack of contrast or slow response times. To overcome these deficiencies we focus on a careful material composition of the colouring hybrid electrodes in our device. We have established a nanoporous Sb-doped SnO $${}_{2}$$ electrode as supporting electrode for chemisorbed electrochromic tetraphenylbenzidine molecules due to its good conductivity in the redox potential range of the molecule. This hybrid electrode was combined with a modified nanoporous TiO $${}_{2}$$ / viologen electrode to realize a high performance, complementary electrochromic device. Fast switching time constants of 0.5 s and concurrently high change in optical density $$\Delta$$ OD = 2.04 at 605 nm confirm our successful concept. The achieved colouration efficiency of 440 cm $${}^{2}$$ C $${}^{-1}$$ exceeds every high contrast device presented so far. Electrochromic devices have a range of applications as switchable shutters. Here the authors report a hybrid device that uses complementary electrochromic molecules immobilized on nanoporous electrodes to concurrently achieve fast colouration and bleaching with high contrast over a broad spectral range.

Permanently doped polyaniline and method thereof

Abstract: The present invention relates to an electrically conducting polymer, the water-insoluble polymer having essentially permanent self-doping properties, and the polynmer comprises: (a) electrically polymerized polyaniline in covalent combination with (b) an organic dopant having at least one sulfonic acid functional group. The electrically conducting polymer-dopant is preferred wherein the organic dopant is selected from benzenesulfonic acid, toluenesulfonic acid, benzenesulfonyl chloride, dodecylbenzenesulfonic acid, poly(vinylsulfonic) acid, trifluoromethanesulfonic acid, 1-butanesulfonic acid, modified NAFION, 2,3,5-trichlorobenzenesulfonic acid, vinylphenylsulfonic acid, or the alkali metal salts thereof. In another aspect, the present invention discloses a method to produce a water-insoluble polyaniline in which an aromatic organic dopant is covalently bonded to the polyaniline, which method comprises (a) electropolymerizing aniline in an aqueous solvent which contains the organic dopant. These permanently doped polyanilines are useful as films for electric battery electrodes, and for electrochromic applications.

Electronic display element

Abstract: An electronic display device having a polyaniline film coated on a transparent electrode. The film has electrochromic properties and will display at least three distinct reproducible color changes.