Nissan Motor Company Limited

Yoshiko Maeda

Takeshi Miyamoto

Shigenori Kazama

Mikio Ura

Takao Kase

An electrochromic device having two electrochromic layers respectively formed on oppositely arranged two electrodes and containing an electrolyte such as a solution of an alkali metal salt in an organic solvent which fills up the gap between the two electrodes. The electrochromic layers are formed of an electrochromic material which can alternately and stably exist in three different oxidation states and assumes three different colors in its respective oxidation states such that there is a clear contrast between the color of this material in its normal or intermediate oxidation state and a composite color given by superposition of the color in the highest oxidation state on the color in the lowest oxidation state. Prussian blue is a preferred example of such an electrochromic material, on condition that an adequate amount of water be present in the electrolyte solution or, alternatively, that the Prussian blue layers be pretreated to substitute alkali metal cation for Fe.sup.3+ interstitially existing in the crystal lattice of Prussian blue.

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Yokohama, Japan

Yoshiko Maeda