Metal nanowire inks for the formation of transparent conductive films with fused networks
Fusing nanowire inks are described that can also comprise a hydrophilic polymer binder, such as a cellulose based binder. The fusing nanowire inks can be deposited onto a substrate surface and dried to drive the fusing process. Transparent conductive films can be formed with desirable properties.
1. A method for forming a transparent conductive network, the method comprising;
depositing a fusing metal nanowire ink onto a substrate surface, wherein the metal nanowire ink comprises from about 0.001 wt % to about 4 wt % metal nanowires, from about 0.05 wt % to about 5 wt % hydrophilic polymer binder, and from about 0.00025 wt % to about 0.5 wt % metal ions; and
drying the metal nanowire ink to form a transparent conductive film comprising fused metal nanowires in the form of a fused metal nanostructured network, the transparent conductive film having a sheet resistance no more than about 250 ohms/sq.
2. The method of claim 1 wherein the metal nanowires comprise silver nanowires and the metal ions comprise silver ions, and wherein the depositing is performed to cover all or a portion of the substrate surface at a metal loading at covered locations from about 0.1 mg/m 2 to about 300 mg/m 2 .
3. The method of claim 1 wherein the hydrophilic polymer binder comprises a polymeric polyol.
4. The method of claim 1 wherein the hydrophilic polymer binder comprises a polysaccharide.
5. The method of claim 1 wherein the hydrophilic polymer binder comprises a cellulose based polymer or chitosan based polymer.
6. The method of claim I wherein the metal nanowires comprise silver nanowires, and wherein the metal nanowire ink comprises from about 0.1 wt % to about 2 wt % polysaccharide polymer binder, and from about 0.001 to about 0.2 wt % metal ions selected from the groups consisting of silver, gold, platinum, palladium, zinc, nickel and combinations thereof.
7. The method of claim 1 wherein the metal nanowire ink further comprises from about 5 wt % to about 60 wt % liquid alcohol.
8. The method of claim 1 wherein the drying is performed by heating to a temperature from about 50° C. to about 150° C. for no more than about 2 hours.
9. The method of claim 1 wherein the drying is performed by heating to a temperature from about 65° C. to about 135° C. for about 30 seconds to about 20 minutes.
10. The method of claim 1 wherein the metal nanowire ink further comprises a curable polymer binder and the method further comprising curing the binder.
11. The method of claim I wherein the transparent conductive film has a sheet resistance of no more than about 100 ohms/sq.
12. The method of claim 1 wherein the transparent conductive film has a transparency of at least about 90%.
13. The method of claim 1 wherein the transparent conductive film has a sheet resistance of no more than about 140 ohms/sq, a % TT of at least about 95% and a haze of no more than about 1.2%, wherein the metal nanostructured network comprises silver.
14. The method of claim 1 wherein the dried film is washed with alcohol.
15. A method for sintering an as deposited metal nanowire ink with metal ions, the method comprising:
drying a metal nanowire film at a temperature from about 60° C. to about 99° C. at a relative humidity of at least about 40% for at least about 1 minute, wherein the metal nanowire film is formed through the deposition of a metal nanowire ink comprising from about 0.001 wt % to about 4 wt % metal nanowires, from about 0.05 wt % to about 5 wt % hydrophilic polymer binder, and from about 0.00025 wt % to about 0.5 wt % metal ions.
16. The method of claim 15 wherein the drying is performed at a relative humidity of no more than about 70% and at a temperature from about 65° C. to about 90° C.
17. The method of claim 15 wherein the hydrophilic polymer binder comprises a cellulose based polymer or chitosan based polymer.
18. The method of claim 15 wherein the metal nanowires comprise silver nanowires and the metal ions comprise silver ions, and wherein the depositing is performed to cover all or a portion of the substrate surface at a metal loading at covered locations from about 0.1 mg/m 2 to about 300 mg/m 2 .
19. The method of claim 15 wherein the metal nanowire ink further comprises from about 5 wt % to about 60 wt % liquid alcohol.
20. The method of claim 15 wherein the dried metal nanowire film has a sheet resistance of no more than about 140 ohms/sq, a % TT of at least about 95% and a haze of no more than about 1.2%, wherein the metal nanowire film comprises silver.