Abstract: The disclosure relates to a novel polymer which is made up of repeating units of N,N,N'N'-tetrapheny-p-phenylenediamine. This polymer is thermoplastic and is soluble in industrially usable organic solvents. The polymer acquires high conductivity by doping with an electron acceptor. The polymer becomes insoluble in organic solvents when it is once doped with an electron acceptor and then dedoped, so that the polymer can be used as an active electrode material in electrolytic devices using an organic solvent. The polymer has electrochromic properties and undergoes two-stage oxidation and two-stage reduction to assume three differently stable states. The polymer exhibits pale yellow color in its reduced state, green color in the first-stage oxidized state and dark blue color in the second-stage oxidized state.

Abstract: The invention relates to an electrochromic (EC) device having oppositely arranged two substrates at least one of which is transparent and each of which is coated with an electrode film on the inside surface, a first EC layer which is formed on the electrode film of one substrate and is formed of a transition metal oxide that takes on color in its electrochemically reduced state, such as WO.sub.3, an opposite EC layer which is formed on the electrode film of the other substrate and is formed of another EC material, such as a polytriphenylamine that takes on color in its electrochemically oxidized state, and an electrolyte solution which uses a nonaqueous solvent and occupies the space between the two substrates. According to the invention, the transition metal oxide layer contains such an amount of adsorption water that the concentration of water in the electrolyte solution in the device becomes more than 0% and not more than 0.3% by weight.

Abstract: A method of electrodepositing a hexacyano-cobalt iron complex of the general formula Fe.sub.x [Co(CN).sub.6 ].sub.y, where 3.ltoreq.x.ltoreq.4 and 2.ltoreq.y.ltoreq.3, which serves as an electrochromic material high in memory effects and quick in response. A film of the cyano-complex is electrodeposited from an aqueous mixed solution of K.sub.3 [Co(CN).sub.6 ] and an iron(III) salt such as FeCl.sub.3. During the electrolytic reduction process the cathode potential is periodically increased and decreased over a predetermined range, preferably from -0.2 to +1.2 V, to stably accomplish electrodeposition to thereby obtain an electrochromic film which is uniform in physical properties and even in the tone and tint of the color. The sweep of the cathode potential may be made in the manner of a saw-tooth wave, rectangular wave or sinusoidal wave.