Solid electrochromic devices

US4298250A · kind A · utility

Assignee

• Bell Telephone Laboratories, Inc. · US

Inventors

• Gary D. Boyd · Rumson, US
• Sarat K. Mohapatra · Woodbury, US
• Benjamin Tell · Matawan, US
• Sigurd Wagner · Princeton, US
• Fred Wudl · Lompoc, US

Key dates

• Filing date: Oct 31, 1978
• Grant date: Nov 3, 1981
• Expiry date: Oct 31, 1998

Classification

• Technology area (CPC G): Physics
• CPC primary: G02F1/1524
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

Solid state electrochromic devices are fabricated using, as the electrochromic material, ionic conductors such as heteropoly acids. The properties of the ionic conductors permit construction of a device having only two electrodes and the electrochromic material. In operation, low voltages impressed between the electrodes induce a color change. For example, when phosphotungstic acid is employed, the color change is from white to dark blue. Cycle times as low as 100 msec are achievable and the devices exhibit memory properties.