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Novel Electrochromic Device Controlled by Sunlight

Lawrence Berkeley National Laboratory

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Technology Marketing SummaryFrank McLarnon and Robert Kostecki at Berkeley Lab have designed a two-component electrode, fabricated with titanium and nickel oxides, reacts to both light and electricity. DescriptionDirect exposure to natural sunlight transforms exposed areas of the electrode from transparent to gray. Nonuniform illumination produces patterned optical states that can be stored or erased using optical read/write capability. Berkeley Lab's new electrode is ideal for 'smart windows' that can use either an external power source or incident sunlight to modify light transmission. Other potential applications include photochromic ophthalmic lenses; tunable neutral density filters; photosensitive mirrors, displays, light detectors, optical switches, light-intensity meters, near-UV radiation detectors, and low-cost optical computer memories. Use of inexpensive components combined with simple construction (only 3 layers compared to 5 in competing electrodes) widens the applicability of such devices, and significantly reduces the cost, compared with related technologies. Benefits
  • Uses inexpensive components
  • Simplier construction than competing solutions
  • Reacts in sunlight
Applications and Industries
  • 'Smart' windows
  • Photochromic ophthalmic lenses
  • Tunable neutral density filters
  • Photosensitive mirrors
  • Displays
  • Light detectors
* Optical switches
* Light-intensity meters
* Near-UV radiation detectors
* Low-cost optical computer memories
More InformationR. Kostecki, T. Richardson, and F. McLarnon, "Photochemical and Photoelectrochemical Behavior of a Novel TiO2/Ni(OH)2 Electrode," J. Electrochem. Soc., Vol. 145, No. 7, July 1998 Patents and Patent Applications
ID Number
Title and Abstract
Primary Lab
Patent 6,118,572
Photochromic, electrochromic, photoelectrochromic and photovoltaic devices
A light activated photoelectrochromic device is formed of a two-component system formed of a photoactive charge carrier generating material and electrochromic material (plus an elecrolyte). Light interacts with a semiconductive material to generate hole-electron charge carriers which cause a redox reaction in the electrochromic material. One device is formed of hydrated nickel oxide as the electrochromic layer and polycrystalline titanium dioxide as the charge generating material. The materials may be formed as discrete layers or mixed together. Because of the direct charge transfer between the layers, a circuit to apply a voltage to drive the electrochromic reaction is not required, although one can be used to enhance the reaction. The hydrated nickel oxide-titanium dioxide materials can also be used to form a photovoltaic device for generating electricity.
Lawrence Berkeley National Laboratory 09/12/2000
Technology Status
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