Optical device fabrication
Transparent conductive coatings are polished using particle slurries in combination with mechanical shearing force, such as a polishing pad. Substrates having transparent conductive coatings that are too rough and/or have too much haze, such that the substrate would not produce a suitable optical device, are polished using methods described herein. The substrate may be tempered prior to, or after, polishing. The polished substrates have low haze and sufficient smoothness to make high-quality optical devices.
1 . A method comprising:
(a) polishing a surface of a first transparent conducting oxide layer disposed on a glass substrate, a time and amount of the polishing having been determined by periodically measuring, during a prior polishing operation of a sample, a sheet resistance of the sample, the determined time and amount of the polishing the surface providing a resulting sheet resistance of the first transparent conducting oxide layer within or below the range of 5 to 30 ohms per square;
(b) cleaning the polished surface and depositing an electrochromic layer in one or more portions on the cleaned polished surface, the electrochromic layer comprising tungsten oxide or doped tungsten oxide, wherein the electrochromic layer comprises a region comprising a greater than stoichiometric amount of oxygen;
(c) depositing a counter electrode layer on the region to form a device stack, wherein the counter electrode layer comprises nickel oxide or nickel tungsten oxide, each optionally doped, the region being located at an interface between the electrochromic layer and the counter electrode layer;
(d) applying lithium to the counter electrode layer; and
(e) heating the device stack to convert the region to an ion conducting and electrically insulating region between the electrochromic layer and the counter electrode layer.
2 . The method of claim 1 , wherein (e) comprises, in order:
(i) heating the device stack in an inert atmosphere;
(ii) heating the device stack in O 2 ; and
(iii) heating the device stack in air.
3 . The method of claim 2 , wherein heating the device stack in air comprises heating the device stack in air at a temperature between about 250° C. to about 350° C. for about 20 minutes to about 40 minutes.
4 . The method of claim 2 , wherein heating the device stack in air at a temperature at about 300° C. for about 30 minutes.
5 . The method of claim 1 , wherein (e) comprises heating the device stack at a temperature between about 150° C. to about 450° C. for about 10 minutes to about 30 minutes in an inert atmosphere and for about 1 minute to about 15 minutes in O 2 .
6 . The method of claim 5 , wherein (e) further comprises heating the device stack in air.
7 . The method of claim 6 , wherein heating the device stack in air comprises heating the device stack in air at a temperature between about 250° C. to about 350° C. for about 20 minutes to about 40 minutes.
8 . The method of claim 6 , wherein heating the device stack in air at a temperature at about 300° C. for about 30 minutes.
9 . The method of claim 1 , wherein (e) comprises heating the device stack at a temperature of about 250° C. for about 15 minutes in an inert atmosphere and for about 1 minute to about 15 minutes in O 2 .
10 . The method of claim 9 , wherein (e) further comprises heating the device stack in air.
11 . The method of claim 10 , wherein heating the device stack in air comprises heating the device stack in air at a temperature between about 250° C. to about 350° C. for about 20 minutes to about 40 minutes.
12 . The method of claim 10 , wherein heating the device stack in air at a temperature at about 300° C. for about 30 minutes.
13 . The method of claim 1 , wherein (c) includes heating the device stack with radiant heat energy or ultraviolet radiation.
14 . The method of claim 1 , wherein the ion conducting and electrically insulating region comprises lithium tungstate.
15 . The method of claim 1 , wherein the ion conducting and electrically insulating region is:
(i) about 10 nm to about 150 nm thick; or
(ii) about 20 nm to about 100 nm thick; or)
(iii) about 30 nm to about 50 nm thick.
16 . The method of claim 1 , wherein the polishing in (a) comprises using an automated polishing apparatus to control polishing the first transparent conducting oxide layer to a surface roughness between 1 nm and 10 nm.
17 . The method of claim 1 , wherein the polishing in (a) of the surface of the first transparent conducting oxide layer further comprises periodically measuring sheet resistance of the first transparent conducting oxide layer during polishing of the first transparent conducting oxide layer.
18 . The method of claim 1 , wherein the ion conducting and electrically insulating region comprises a metal oxide material.
19 . The method of claim 18 , wherein the metal oxide material comprises one of tungsten oxide, molybdenum oxide, niobium oxide, titanium oxide, tantalum oxide, zirconium oxide, and cerium oxide.
20 . The method of claim 1 , wherein the ion conducting and electrically insulating region comprises one of lithium tungstate, lithium molybdate, lithium niobate, lithium tantalite, lithium titanate, and lithium zirconate.
21 . The method of claim 1 , further comprising, after (d) and before (e), depositing a transparent conductive oxide layer on the counter electrode layer.
22 . A method comprising:
(a) polishing a surface of a first transparent conducting oxide layer disposed on a glass substrate, a time and amount of the polishing having been determined by periodically measuring, during a prior polishing operation of a sample, a sheet resistance of the sample, the determined time and amount of the polishing the surface providing a resulting sheet resistance of the first transparent conducting oxide layer within or below the range of 5 to 30 ohms per square;
(b) cleaning the polished surface and depositing an electrochromic layer in one or more portions on the cleaned polished surface, the electrochromic layer comprising tungsten oxide or doped tungsten oxide, wherein the electrochromic layer comprises a region comprising a greater than stoichiometric amount of oxygen;
(c) depositing a counter electrode layer on the region to form a device stack, wherein the counter electrode layer comprises nickel oxide or nickel tungsten oxide, each optionally doped, the region being located at an interface between the electrochromic layer and the counter electrode layer;
(d) applying lithium to the counter electrode layer; and
(e) heating the device stack to convert the region to an ion conducting and electrically insulating region between the electrochromic layer and the counter electrode layer,
wherein the sample is a sample of the first transparent conducting oxide layer.
23 . The method of claim 1 , wherein the determined time and the determined amount of polishing are respectively a remaining time and a remaining amount of polishing.