Variable transmission optical device

A variable transition optical device comprising a first layer of a transparent electrically conductive material,

• a first layer of an electrochromic material comprising a metal-sensitive compound which is capable of dissolving guest metal atoms and which changes colour in doing so,
• a layer of a transparent, solid electrolyte, the solid electrolyte being a fast ion conductor in which a fast ion is an ion of the metal which dissolves in the said metal-sensitive compound to change the colour thereof,
• a transparent guest metal sink comprising a solid solution of MoO.sub.3 and V.sub.2 O.sub.5 which is capable of dissolving the same metal atoms as the first electrochromic layer,
• a second layer of transparent electrically conductive material,
• the said layers being positioned in the order specified, the said layer of solid electrolyte being in contact with the layer of electrochromic material and the guest metal sink layer, and the said first and second conductive layers being in contact with the electrochromic layer and the guest metal sink layer respectively,
• there being provided in the device a quantity of the said metal colouration atoms which may be transferred reversibly from the guest metal sink layer to the electrochromic layer by application of a potential difference between the said first and second electrically conductive layers.

A method for producing a variable transmission optical device comprising a first layer of a transparent electrically conductive material, a first layer of an electrochromic material comprising a metal-sensitive compound which is capable of dissolving guest metal atoms and which changes colour in so doing, a layer of transparent, solid electrolyte, the solid electrolyte being a fast ion conductor in which a fast ion is an ion of the metal which dissolves in the said metal-sensitive compound to change the colour thereof, a discontinuous transparent guest metal sink layer comprising a compound which is capable of dissolving the same metal atoms as the first electrochromic layer which guest metal sink layer comprises a distributed multitude of small areas at least substantially free of said compound, a second layer of transparent electrically conductive material, the said layers being positioned in the order specified, the said layer of solid electrolyte being in contact with the layer of electrochromic material and the guest metal sink layer, and the said first and second conductive layers begin in contact with the electrochromic layer and the guest metal sink layer respectively, there being provided in the device a quantity of the said guest metal colouration atoms which may be transferred reversibly to the electrochromic layer by application of a potential difference between the said first and second electrically conductive layers, the layer of electrochromic material and the guest metal sink layer being chosen such that a given quantity of metal colouration atoms produces a colouration of greater density when dissolved in the electrochromic layer than when dissolved in the discontinuous guest metal sink layer, whereby the overall optical absorption property of the device can be varied by transfer of metal atoms between the layer of electrochromic material and the guest metal sink layer, wherein an insulating layer is provided between the solid electrolyte and the electrically conductive material having a pattern complimentary to that of the layer of the guest metal sink material, so that the guest metal sink material occupies spaces in the layer of insulating material, which method comprises:

• providing over a respective surface of electrically conductive material a layer of photo-resist;
• exposing the photo-resist with a pattern the negative of the desired insulating layered pattern;
• developing the photo-resist to leave a said negative pattern of photo-resist;
• depositing the insulating layer over the electrically conductive material and the photo-resist;
• stripping off the photo-resist to leave the positive pattern of insulating material;
• depositing the desired guest metal sink material over the remaining area of the electrically conductive material;
• and
• depositing or otherwise providing the remaining layers of the device.