Laser patterning of silver nanowire-based transparent electrically conducting coatings
A transparent electrical conductor ( 10; 20 ), comprising a transparent substrate ( 14; 201 ); a composite layer ( 18; 28 ) comprising an electrically conductive layer ( 12 ) disposed on at least a portion of a major surface of the transparent substrate ( 14; 201 ) and comprising a plurality of interconnecting metallic nanowires, and a polymeric overcoat layer ( 16 ) disposed on at least a portion of the electrically conductive layer ( 12 ); wherein a pattern in the composite layer includes an x-axis and a y-axis of an x-y plane of the composite layer and a z-axis into the x-y plane of the composite layer, and the pattern defines a plurality of electrically conductive regions ( 24, 24′ ) in the x-y plane of the composite layer ( 18; 28 ), wherein the electrically conductive regions ( 24, 24′ ) are separated from each other by electrically insulative traces ( 21 ), each of which defines a valley into the z-axis of the x-y plane of the composite layer ( 18; 28 ), the valley having a maximum depth ( 27 ) in a range from 50 nanometers to 100 nanometers relative to the x-y plane of the composite layer ( 18; 28 ), wherein the valley has a cross-sectional width (M 1 ) in a range from 10 micrometers to 1000 micrometers, and wherein the valley further comprises a plurality of crevices ( 22 ) having a depth ( 23 ) in a range from 50 nanometers to 100 nanometers further into the z-axis of the x-y plane of the composite layer ( 18; 28 ). Methods for patternwise irradiating transparent electrodes ( 10; 20 ) to generate electrically insulating traces ( 21 ) are also described.
1. A transparent electrical conductor, comprising:
a transparent substrate;
a composite layer comprising:
an electrically conductive layer disposed on at least a portion of a major surface of the transparent substrate and comprising a plurality of interconnecting metallic nanowires; and
a polymeric overcoat layer disposed on at least a portion of the electrically conductive layer;
wherein a pattern in the composite layer includes an x-axis and a y-axis of an x-y plane of the composite layer and a z-axis into the x-y plane of the composite layer, and the pattern defines a plurality of electrically conductive regions in the x-y plane of the composite layer, wherein the electrically conductive regions are separated from each other by electrically insulative traces, each of which defines a valley into the z-axis of the x-y plane of the composite layer, the valley having a maximum depth in a range from 10 nanometers to 100 nanometers relative to the x-y plane of the composite layer, wherein the valley has a cross-sectional width in a range from 10 micrometers to 1000 micrometers, and wherein the valley further comprises a plurality of crevices having a depth in a range from 50 nanometers to 100 nanometers further into the z-axis of the x-y plane of the composite layer.
2. The transparent electrical conductor of claim 1 , wherein a depth of at least some of the crevices is at least 100 nanometers into the z-axis of the x-y plane of the composite layer, relative to the x-y plane of the composite layer.
3. The transparent electrical conductor of claim 1 , wherein the valley has a lateral ridge along an edge of the valley, wherein the lateral ridge rises no more than 1% along the z-axis above the surface plane relative to the maximum depth of the valley.
4. The transparent electrical conductor of claim 1 , wherein the polymeric overcoat layer comprises a reaction product of at least one multifunctional (meth)acrylate.
5. The transparent electrical conductor of claim 1 , wherein the polymeric overcoat layer comprises metal oxide nanoparticles.
6. The transparent electrical conductor of claim 1 , wherein the polymeric overcoat layer comprises an electroactive polymer.
7. The transparent electrical conductor of claim 1 , wherein the plurality of interconnecting metal nanowires comprises silver.
8. The transparent electrical conductor of claim 1 , wherein the transparent substrate is a layer having a thickness in a range from about 5 micrometers to about 1000 micrometers.
9. The transparent electrical conductor of claim 1 , wherein the electrically conductive layer has a thickness in a range from about 50 nanometers to about 1 micrometer.
10. The transparent electrical conductor of claim 1 , wherein the composite layer has a thickness in a range from about 50 nanometers to about 1 micrometer.
11. The transparent electrical conductor of claim 1 , wherein the electrically insulative trace provides an electrical resistance of greater than 1 megaohm between the electrically conductive regions in the plurality of electrically conductive regions.
12. An article comprising the transparent electrical conductor of claim 1 .
13. A method for making the transparent electrode of claim 1 , the method comprising:
providing a transparent electrically conductive film comprising:
a transparent substrate;
a composite layer comprising:
an electrically conductive layer disposed on at least a portion of a major surface of the transparent substrate and comprising a plurality of interconnecting metallic nanowires; and
a polymeric overcoat layer disposed on at least a portion of the electrically conductive layer; and
patternwise irradiating the transparent electrically conductive film according to a pattern to provide the transparent electrode.
14. The method of claim 13 , wherein the patternwise irradiating comprises irradiation with a laser.
15. The method of claim 14 , wherein the laser is a pulsed UV laser.
16. The method of claim 14 , wherein the laser is a continuous wave UV laser.
17. The method of claim 13 , wherein the patternwise irradiating comprises a roll-to-roll processing of the transparent electrically conductive film.
18. The method of claim 13 , wherein the patternwise irradiating comprises severing at least some of the plurality of interconnecting metallic nanowires.
19. The method of claim 13 , wherein the patternwise irradiating comprises disrupting of at least some of the plurality of interconnecting metallic nanowires within an irradiated area and redistributing metal from the metallic nanowires into a nonconducting, non-nanowire layer within the irradiated area.