Particle removal during fabrication of electrochromic devices

Abstract

Electrochromic devices are fabricated using a particle removal operation that reduces the occurrence of electronically conducting layers and/or electrochromically active layers from contacting layers of the opposite polarity and creating a short circuit in regions where defects form. In some embodiments, the particle removal operation is not a lithiation operation. In some embodiments, the particle removal operation is performed at an intermediate stage during the deposition of either an electrochromic layer or a counter electrode layer.

1 . A method of fabricating an electrochromic device, the method comprising:
 providing a substrate having a first transparent electronically conductive layer comprising a first transparent electronically conductive material;   forming an electrochromic stack over the substrate having the first transparent electronically conductive layer, wherein forming the stack comprises:
 forming an electrochromic layer comprising an electrochromic material; and 
 forming a counter electrode layer comprising a counter electrode material; 
   forming a second transparent electronically conductive layer over the electrochromic stack, the second transparent electronically conductive layer comprising a second transparent electronically conductive material, whereby the first and second transparent electronically conductive layers sandwich the electrochromic stack; and   performing a particle-removal operation to reduce the number of defects in the formed electrochromic device, wherein the particle-removal operation is performed at any time before both the electrochromic layer and the counter electrode layer are fully-formed.   
     
     
         2 . The method of  claim 1 , wherein the particle removal operation reduces the number of visible short-related pinhole in the formed electrochromic device. 
     
     
         3 . The method of  claim 1 , wherein:
 the first transparent electronically conductive material is selected from the group consisting of fluorinated tin oxide and indium-doped tin oxide; and   the second transparent electronically conductive material is indium-doped tin oxide.   
     
     
         4 . The method of  claim 1 , wherein the particle-removal operation is performed before starting to form either the electrochromic or counter electrode layers. 
     
     
         5 . The method of  claim 1 , wherein the particle-removal operation is performed after the electrochromic layer is formed but before starting to form the counter electrode layer. 
     
     
         6 . The method of  claim 1 , wherein the particle-removal operation is performed after the counter electrode layer is formed but before starting to form the electrochromic layer. 
     
     
         7 . The method of  claim 1 , wherein the particle-removal operation is performed after starting to form the electrochromic layer but before the electrochromic layer is fully formed. 
     
     
         8 . The method of  claim 1 , wherein the particle-removal operation is performed after starting to form the counter electrode layer but before the counter electrode layer is fully formed. 
     
     
         9 . The method of  claim 1 , wherein the particle-removal operation comprises a technique selected from the group consisting of contact cleaning, irradiation, heat treatment, plasma treatment, contact with supercritical fluid, acoustic vibration, and contact with flowing ionized air. 
     
     
         10 . The method of  claim 1 , wherein the particle-removal operation comprises contact cleaning, and wherein the contact cleaning removes particles from the surface of the partially-formed electrochromic device by static electricity and/or adhesion. 
     
     
         11 . The method of  claim 10 , wherein the contact cleaning comprises contacting the surface of the partially-formed electrochromic device with one or more rollers, strips, or brushes. 
     
     
         12 . The method of  claim 1 , wherein the particle-removal operation comprises irradiating the surface of the partially-formed electrochemical device, and wherein the irradiation produces a volumetric expansion of the particles to be removed relative to the surrounding portions of the partially-formed electrochromic device such that these particles are ejected from the surface of the partially-formed electrochromic device. 
     
     
         13 . The method of  claim 1 , wherein the particle-removal operation comprises contacting the surface of the partially-formed electrochromic device with a plasma. 
     
     
         14 . The method of  claim 13 :
 wherein the plasma contact produces a build-up of electrical charge in the particles to be removed; and   wherein the particle-removal operation further comprises applying a voltage to an outer surface of the partially-formed electrochromic device such that the charged particles to be removed are ejected from the surface by repulsive electrostatic forces.   
     
     
         15 . The method of  claim 13 , wherein the plasma is a fluorine and/or oxygen plasma which etches away a film from the surface of the partially-formed electrochromic device such that particles are dislodged and/or removed with the film. 
     
     
         16 . The method of  claim 1 , wherein the particle-removal operation comprises a heat treatment of the partially-formed electrochromic device. 
     
     
         17 . The method of  claim 16 , wherein the heat treatment comprises heating the particles to be removed so as to cause the particles to volumetrically expand relative to the surrounding portions of the partially-formed electrochromic device such that the particles are ejected from the surface of the partially-formed electrochromic device. 
     
     
         18 . The method of  claim 17 , wherein the heat-treatment comprises a heating technique selected from: irradiation with UV light, proximity to a resistive heating element, and exposure to a heated gas. 
     
     
         19 . The method of  claim 1 , wherein the particle-removal operation comprises dislodging or burning away particles from the surface of the partially-formed electrochromic device with laser radiation. 
     
     
         20 . The method of  claim 19 , wherein the laser radiation is collimated into a flat beam which grazes the surface of the partially-formed electrochromic device. 
     
     
         21 . The method of  claim 20 , wherein the laser radiation is raster-scanned over the surface of the partially-formed electrochromic device. 
     
     
         22 . The method of  claim 1 , wherein the electrochromic material of the electrochromic layer is cathodically-coloring, wherein the counter electrode material of the counter electrode layer is anodically-coloring, and wherein the electrochromic layer is formed before forming the counter electrode layer. 
     
     
         23 . The method of  claim 22 , wherein the cathodically-coloring electrochromic material comprises a tungsten oxide, and the anodically-coloring electrochromic material comprises a nickel tungsten oxide. 
     
     
         24 . The method of  claim 23 , wherein forming the electrochromic stack further comprises forming an additional layer comprising tungsten oxide having a different tungsten to oxygen ratio than the tungsten oxide comprising the other cathodically-coloring electrochromic material. 
     
     
         25 . The method of  claim 1 , further comprising depositing lithium into the electrochromic stack. 
     
     
         26 . The method of  claim 1 , wherein the electrochromic stack is formed on the substrate while the substrate is oriented vertically. 
     
     
         27 . The method of  claim 1 , wherein the electrochromic stack is formed on the substrate while the substrate is oriented horizontally. 
     
     
         28 . An apparatus for fabricating an electrochromic device, the apparatus comprising:
 (a) an integrated deposition system for forming an electrochromic stack on a substrate, the system comprising:
 (i) a first deposition station containing a first target comprising a first material for depositing a layer of an electrochromic material on a substrate when the substrate is positioned in the first deposition station; 
 (ii) a second deposition station containing a second target comprising a second material for depositing a layer of a counter electrode material on the substrate when the substrate is positioned in the second deposition station; and 
 (iii) a particle-removal device for removing particles from the surface of the substrate and/or the surface of the electrochromic stack before it is fully-formed; and 
   (b) a controller comprising:
 program instructions for passing the substrate through the first and second deposition stations in a manner that sequentially deposits a stack on the substrate, the stack comprising the layer of electrochromic material and the layer of counter electrode material; and 
 program instructions for operating the particle-removal device to remove particles from the surface of the substrate and/or the surface of the electrochromic stack before it is fully-formed. 
   
     
     
         29 . The apparatus of  claim 28 , wherein the program instructions comprise instructions for operating the particle-removal device to remove particles before the layer of electrochromic material is fully-formed. 
     
     
         30 . The apparatus of  claim 28 , wherein the program instructions comprise instructions for operating the particle-removal device to remove particles before the counter electrode layer is fully formed. 
     
     
         31 . The apparatus of  claim 28 , wherein operation of the particle-removal device reduces the number of visible short-related pinhole defects in the fabricated electrochromic device to a level no greater than about 0.005 per square centimeter. 
     
     
         32 . The apparatus of  claim 28 , wherein the integrated deposition system further comprises:
 (iv) a third deposition station containing a third target comprising a third material, wherein the third deposition station is configured to deposit an electrode layer on the electrochromic stack when the substrate having the electrochromic stack is positioned in the third deposition station, and wherein the electrode layer comprises a transparent electronically conductive material.   
     
     
         33 . The apparatus of  claim 28 , further comprising a substrate holder configured to provide the substrate in a vertical orientation when positioned for deposition in the first and second deposition stations. 
     
     
         34 . The apparatus of  claim 33 , wherein the apparatus is further configured to provide the substrate in a vertical orientation when positioned at the particle-removal device. 
     
     
         35 . The apparatus of  claim 28 , further comprising a substrate holder configured to provide the substrate in a horizontal orientation when positioned for deposition in the first and second deposition stations. 
     
     
         36 . The apparatus of  claim 35 , wherein the apparatus is further configured to provide the substrate in a horizontal orientation when positioned at the particle-removal device.