Nanowires-based transparent conductors
View Patent ↗A method for forming a transparent conductor including a conductive layer coated on a substrate is described. The method comprises depositing a plurality of metal nanowires on a surface of a substrate, the metal nanowires being dispersed in a liquid; and forming a metal nanowire network layer on the substrate by allowing the liquid to dry.
1. A method of fabricating a transparent conductor comprising:
depositing a coating composition on a surface of a substrate, the coating composition comprising: a liquid and a plurality of conductive nanostructures consisting of silver nanowires, wherein the silver nanowires are 0.05% to 1.4% of a total weight of the coating composition;
forming a silver nanowire network layer on the substrate by allowing the liquid to dry, wherein the silver nanowires intersect to provide the silver nanowire network layer;
providing a corrosion inhibitor;
forming a matrix material layer on the silver nanowire network layer, wherein the matrix material layer is conductive; and
defining a pattern with a first region and a second region, wherein the silver nanowire network layer is located in the first region to form a conductive region, the matrix material layer in the second region is totally removed and the silver nanowires in the second region are partially removed to reduce a concentration of the silver nanowires in the second region to a level below a percolation threshold so that the second region defines a non-conductive region.
2. The method of claim 1 wherein the coating composition further comprises an additive selected from carboxy methyl cellulose, 2-hydroxy ethyl cellulose, hydroxy propyl methyl cellulose, methyl cellulose, poly vinyl alcohol, tripropylene gylcol, and xanthan gum.
3. The method of claim 1 further comprising pre-treating the surface of the substrate prior to depositing the coating composition.
4. The method of claim 3 wherein pre-treating the surface of the substrate creates a pattern comprising at least one pre-treated region and at least one untreated region.
5. The method of claim 4 wherein the silver nanowire network layer is only formed on the pre-treated region.
6. The method of claim 3 wherein pre-treating the surface of the substrate comprises depositing an intermediate layer on the surface of the substrate, performing a plasma treatment to the surface of the substrate, performing an UV-ozone treatment to the surface of the substrate, or performing a corona discharge treatment to the surface of the substrate.
7. The method of claim 1 further comprising applying pressure, heat or a combination thereof to the silver nanowire network layer.
8. The method of claim 1 wherein forming the matrix material layer on the silver nanowire network layer comprises:
depositing a matrix material on the silver nanowire network layer; and
curing the matrix material to form the matrix material layer, wherein the silver nanowires are dispersed or embedded in the matrix material layer to form a conductive layer.
9. The method of claim 8 further comprising:
causing at least a section of each of the silver nanowires to protrude above a surface of the matrix material layer to provide a conducting surface of the conductive layer.
10. The method of claim 8 wherein the matrix material comprises a polymer dispersed in a solvent or a prepolymer.
11. The method of claim 10 wherein the prepolymer is photo-curable.
12. The method of claim 8 wherein the matrix material layer is formed into a patterned matrix material layer.
13. The method of claim 8 wherein the substrate is flexible.
14. The method of claim 13 wherein curing the matrix material comprises continuously exposing the matrix material to light irradiation, and the light irradiation is projected to the matrix material according to a pattern.
15. The method of claim 8 wherein the substrate is a flexible donor substrate.
16. The method of claim 15 wherein the flexible donor substrate is coated with a release layer.
17. The method of claim 15 further comprising detaching the conductive layer from the flexible donor substrate and applying the conductive layer to a substrate of choice.
18. The method of claim 1 wherein each of the silver nanowires has an aspect ratio of about 50 or more.
19. The method of claim 1 wherein each of the silver nanowires has an aspect ratio of about 100 or more.
20. The method of claim 1 wherein the liquid is water, an alcohol, a ketone, an ether, a hydrocarbon or an aromatic solvent.
21. The method of claim 1 wherein the coating composition further comprises one or more surfactants.
22. The method of claim 21 wherein the one or more surfactants are fluorinated alkyl ester, polyoxyethylene octyl phenyl ether, 2,5,8,11-tetraethyl-6-dodecyn-5,8-diol ethoxylate, or n-Dodecyl-β-D-maltoside.
23. The method of claim 1 wherein a portion of the silver nanowire network layer extending through the matrix material layer has a threshold surface loading level of about 0.05 μg/cm 2 to about 10 μg/cm 2 .
24. The method of claim 23 wherein the threshold surface loading level is about 0.1 μg/cm 2 to about 5 μg/cm 2 .
25. The method of claim 24 wherein the threshold surface loading level is about 0.8 μg/cm 2 to about 3 μg/cm 2 .
26. The method of claim 1 wherein the matrix material layer comprises a conductive polymer.
27. The method of claim 26 wherein the conductive polymer comprises poly(3,4-ethylenedioxythiophene), polyanilines, polythiophenes, or polydiacetylenes.
28. The method of claim 1 wherein the silver nanowires are embedded in a portion of the matrix material layer.
29. The method of claim 1 wherein the silver nanowires are alloyed or plated with another metal.
30. The method of claim 29 wherein the silver nanowires are plated with gold.
31. The method of claim 1 wherein the corrosion inhibitor binds to the silver nanowires to form a protective film on the silver nanowire network layer.
32. The method of claim 1 wherein the silver nanowire network layer further comprises a plurality of reservoirs each containing the corrosion inhibitor.
33. The method of claim 1 wherein the liquid comprises solvents that are 94.5% to 99.0% of the total weight of the coating composition; and wherein the coating composition further comprises:
a surfactant that is 0.0025% to 0.1% of the total weight of the coating composition; and
a viscosity modifier that is 0.02% to 4% of the total weight of the coating composition.
34. The method of claim 1 wherein providing the corrosion inhibitor comprises dipping the silver nanowire network layer in a solution of the corrosion inhibitor.
35. The method of claim 1 wherein providing the corrosion inhibitor comprises coating a layer of the corrosion inhibitor on the silver nanowire network layer.
36. The method of claim 1 wherein providing the corrosion inhibitor comprises incorporating the corrosion inhibitor in the matrix material layer.
37. The method of claim 1 wherein forming the matrix material layer on the silver nanowire network layer comprises:
coating a prepolymer on the silver nanowire network layer;
curing the prepolymer in the first region; and
totally removing the prepolymer in the second region.
38. The method of claim 1 further comprising:
exposing the silver nanowire network layer in a reducing agent.
39. The method of claim 38 wherein the reducing agent comprises borohydrides, boron nitrogen compounds, or hydrogen gas.