Flexible transparent electrodes via nanowires and sacrificial conductive layer
View Patent ↗A flexible, transparent electrode structure and a method of fabrication thereof are provided comprising a transparent electrode which may maintain electrical connectivity across a surface of a flexible substrate so that the substrate may flex without affecting the integrity of an electrical contact. The transparent electrode includes conductive nanowires that are coupled to the substrate through a conducting oxide layer. The conducting oxide layer effectively provides a template onto which the nanowires are deposited and serves to anchor the nanowires to the substrate surface.
1. A method of fabricating a patterned flexible substrate comprising:
providing a flexible substrate having a patterned layer comprising a conducting oxide layer formed over at least one surface of the substrate;
forming a second conductive layer comprising conductive nanowires directly on the conducting oxide layer wherein the patterned layer has a line spacing of less than about 25 μm, wherein forming the second conductive layer comprises one of the following:
(a) providing a medium comprising binding salts and the conductive nanowires;
immersing the flexible substrate in the medium; and
applying a voltage across the conducting oxide layer and a counter electrode; or
(b) providing a medium comprising the conductive nanowires;
immersing the flexible substrate in the medium; and
providing sonic waves or pressure waves to the medium and immersed substrate.
2. The method of claim 1 , wherein forming the second conductive layer comprises
providing a medium comprising binding salts and the conductive nanowires;
immersing the flexible substrate in the medium; and
applying a voltage across the conducting oxide layer and a counter electrode.
3. The method of claim 1 , wherein forming the second conductive layer comprises
providing a medium comprising the conductive nanowires;
immersing the flexible substrate in the medium; and
providing sonic waves or pressure waves to the medium and immersed substrate.
4. The method of claim 1 , wherein the conducting oxide layer has a thickness less than about 500 Å.
5. The method of claim 4 , wherein the conducting oxide layer has a thickness ranging from about 50 Å to about 200 Å.
6. The method of claim 1 , wherein the conducting oxide layer comprises a transparent conducting oxide.
7. The method of claim 6 , wherein the transparent conducting oxide comprises a doped indium oxide, a doped zinc oxide, antimony tin oxide, cadmium stannate, zinc stannate, or mixtures thereof.
8. The method of claim 7 , wherein the transparent conducting oxide comprises indium tin oxide.
9. The method of claim 1 , wherein the conductive nanowires comprise single-walled carbon nanotubes, multi-walled carbon nanotubes, or mixtures thereof.
10. The method of claim 1 , wherein the flexible substrate comprises polyethylene naphthalate, polyimide, polyethersulfone, polyurethane, polycarbonate, or mixtures thereof.
11. The method of claim 1 , where the flexible substrate is transparent.
12. A method of fabricating a patterned flexible substrate comprising:
providing a flexible substrate having a conducting layer formed over at least one surface of the substrate, wherein
the conducting layer comprises a conducting oxide layer formed over the flexible substrate and a second conductive layer comprising conductive nanowires formed directly on the conducting oxide layer,
forming a photoresist layer over the second conductive layer;
patterning and developing the photoresist layer to provide masked and unmasked portions of the conducting layer; and
etching the unmasked portions of the conducting layer to yield a patterned conducting layer comprising the conducting oxide layer and the second conductive layer and having a line spacing of less than about 25 nm.
13. The method of claim 12 , wherein the providing a flexible substrate having a conducting layer formed over at least one surface of the substrate comprises
providing a flexible substrate;
forming a conducting oxide layer over the flexible substrate; and
forming a second conductive layer comprising conductive nanowires directly on the conducting oxide layer.
14. The method of claim 13 , wherein the conducing oxide layer is formed by sputtering.
15. The method of claim 13 , wherein the second conductive layer is formed by electrophoretic deposition, spray-coating, dip-coating, ink-jet printing, or solution casting of the conductive nanowires from a medium comprising the conductive nanowires onto the conducting oxide layer.
16. The method of claim 12 , wherein the conducting oxide layer has a thickness less than about 500 Å.
17. The method of claim 16 , wherein the conducting oxide layer has a thickness ranging from about 50 Å to about 200 Å.
18. The method of claim 12 , wherein the conducting oxide layer comprises a transparent conducting oxide.
19. The method claim 18 , wherein the transparent conducting oxide comprises a doped indium oxide, a doped zinc oxide, antimony tin oxide, cadmium stannate, zinc stannate, or mixtures thereof.
20. The method of claim 19 , wherein the transparent conducting oxide comprises indium tin oxide.
21. The method of claim 12 , wherein the conductive nanowires comprise single-walled carbon nanotubes, multi-walled carbon nanotubes, or mixtures thereof.
22. The method of claim 12 , wherein the flexible substrate comprises polyethylene naphthalate, polyimide, polyethersulfone, polyurethane, polycarbonate, or mixtures thereof.
23. The method of claim 12 , where the flexible substrate is transparent.