Method for forming tungsten oxide films

• US 5,034,246 A
• Filed: 08/15/1990
• Issued: 07/23/1991
• Est. Priority Date: 08/15/1990
• Status: Expired due to Fees

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Maheswari, Shyam P., Habib, Mohammad A., Mance, Andrew M., Micheli, Adolph L.
• Primary Examiner(s): BELL, JANYCE A
• Application Number:
  US07/568,293
• Time in Patent Office: 342 Days
• Field of Search: 426/226, 426/380, 426/106, 426/108, 426/126.3, 426/126.1, 426/165
• US Class Current: 427/126.3
• CPC Class Codes: C23C 18/06 Coating on selected surface areas, e.g. using masks
• CPC Class Codes: C23C 18/1216 Metal oxides C23C18/1212 takes precedence
• CPC Class Codes: C23C 18/1279 performed under reactive atmosphere, e.g. oxidising or reducing atmospheres

Abstract

A method is disclosed for forming a tungsten oxide film on a substrate by applying an alkyl amine tungstate compound thereon and removing at least a portion of the alkyl amine tungstate compound to form a tungsten oxide film.

In a preferred embodiment, a solution of alkyl amine tungstate compound is formed in a solvent to uniformly apply the alkyl amine tungstate compound; the solvent is removed by evaporation thereby forming a deposit; the deposit is heated for a time and at a temperature sufficient to at least partially pyrolyze the alkyl amine tungstate compound.

The alkyl amine tungstate compound desirably may be selected from the group consisting of bis (di-n-octylammonium) tetratungstate, and di (n-octadecylammonium) tetratungstate. Preferably, bis (di-n-octylammonium) tetratungstate is used.

The invention also provides tungsten oxide films which include suboxides of tungsten oxides (WO₃); which have an average ratio of oxygen atoms to tungsten atoms equal to or less than 3:1; which are denser than films produced from currently known MOD precursor compounds; which have a color gradient, that is, regions of different color; and wherein the regions of color are electrochromic.

Claims

1. A method for forming a tungsten oxide film comprising the steps of:

a) applying onto a substrate a solution containing an alkyl amine tungstate compound,

b) drying said solution to form a deposit, and

c) heating said deposit for a time and at a temperature sufficient to pyrolyze at least a portion of said alkyl amine tungstate compound to form a tungsten oxide film.

2. A method according to claim 1 wherein said alkyl amine tungstate compound comprises an alkyl amine tetratungstate compound.

3. A method according to claim 1 wherein said alkyl amine tungstate compound is selected from the group consisting of bis (di-n-octylammonium) tetratungstate, and di (n-octadecylammonium) tetratungstate.

4. A method according to claim 1 wherein said solution comprises a vaporizable organic solvent.

5. A method according to claim 4 wherein said solvent is a mixture of 2-propanol and xylene.

6. A method according to claim 1 wherein regions of said deposit are heated while varying said time for each respective one of said regions.

7. A method according to claim 1 wherein regions of said deposit are heated while varying said temperature for each respective one of said regions.

8. A method according to claim 1 wherein said solution consists of an organic compound which includes one of the group of boron, silicon, phosphorus, lithium, tantalum, and palladium.

9. A method for forming a tungsten oxide film comprising the steps of:

a) applying onto a substrate a solution containing an alkyl amine tungstate compound dissolved in a vaporizable organic solvent,

b) vaporizing said solvent from the applied solution to produce a deposit on said substrate composed predominantly of said alkyl amine tungstate compound, and

c) heating the deposit in the presence of an oxygen containing atmosphere for a time greater than 5 minutes and at a temperature greater than 450°

C. to decompose said alkyl amine tungstate compound to produce a tungsten oxide film having electrochromic characteristics.

10. The method according to claim 9 wherein said temperature is between about 450°

C. and 550°

C. and said time is between about 5 and 10 minutes, thereby forming a brown tungsten oxide film.

11. The method according to claim 9 wherein said temperature is between about 550°

C. and 700°

C. and said time is about 5 minutes, thereby forming a faint yellow to white tungsten oxide film which has a percentage by weight of tungsten and oxygen greater than 99 percent.

12. The method according to claim 9 wherein said temperature is between about 450°

C. and 550°

C. and said time is between about 15 and 25 minutes, thereby forming a faint yellow to white tungsten oxide film which as a percentage by weight of tungsten and oxygen greater than 99 percent.

13. A method for forming a tungsten oxide film comprising the steps of:

a) applying onto an ITO coated substrate a solution containing an alkyl amine tungstate compound dissolved in 50;

50 2-propanol;

xylene solvent,

b) vaporizing said 50;

50 2-propanol;

xylene solvent from the applied solution to produce a deposit on said ITO coated substrate composed predominately of said alkyl amine tungstate compound, and

c) heating the deposit in the presence of an oxygen containing atmosphere for a time between about 20 and 25 minutes and at a temperature between about 450°

C. and 510°

C. to decompose said alkyl amine tungstate compound to produce a tungsten oxide film which in a reduced state has a transmittance between 800-1200 nm which is less than 25 percent and which in an oxidized state has a transmittance between 400-1200 nm which is greater than 80 percent.