Electrically conductive polymeric compositions, contacts, assemblies, and methods
View Patent ↗Electrically conductive polymeric compositions adapted for use in forming electronic devices are disclosed. The compositions are thermally curable at temperatures less than about 250° C. Compositions are provided which may be solvent-free and so can be used in processing or manufacturing operations without solvent recovery concerns. The compositions utilize (i) fatty acid modified epoxy acrylate and/or methacrylate monomer(s) and/or oligomer(s), (ii) fatty acid modified polyester acrylate and/or methacrylate monomer(s) and/or oligomer(s), or combinations of (i) and (ii). Also described are electronic assemblies such as solar cells using the various compositions and related methods.
1. A photovoltaic device comprising a plurality of layers, and an electrically conductive member, the electrically conductive member formed from a composition comprising:
(a) from about 70% to about 90% by weight of electrically conductive silver particles; and
(b) from about 0.1% to about 30% by weight of a selection from the group consisting of
(i) fatty acid modified epoxy acrylate and/or methacrylate monomer(s) or oligomer(s),
(ii) fatty acid modified polyester acrylate and/or methacrylate monomer(s) or oligomer(s), and
(iii) combination of (i) and (ii) wherein the composition is solvent-free and in the form of a paste that can be screen printed onto a substrate and thereafter cured at a temperature of less than 250° C. to form an electrically conductive contact, trace, circuit and/or other electrically conductive region.
2. The device of claim 1 wherein the plurality of layers comprises a layer of a transparent conductive oxide, a layer of indium tin oxide, a layer of aluminum, a layer of copper indium gallium (di)selenide (CIGS), a layer of amorphous silicon and a layer of a crystalline silicon material, or any combination of the layers.
3. The photovoltaic device of claim 1 , wherein the composition further comprises an effective amount of a reactive diluent.
4. The photovoltaic device of claim 3 , wherein the reactive diluent is hexane diol diacrylate.
5. The photovoltaic device of claim 4 , wherein the hexane diol diacrylate is used at a concentration of from about 1% to about 10%.
6. The photovoltaic device of claim 1 , wherein the composition further comprises an effective amount of a free radical initiator.
7. The photovoltaic device of claim 6 , wherein the free radical initiator is selected from the group consisting of (i) 2,5-dimethyl-2,5-di(t-butylperoxy)-3-hexyne, (ii) dicumyl peroxide, and (iii) combinations thereof.
8. The photovoltaic device of claim 6 , wherein the free radical initiator is at a concentration of from about 0.01% to about 2%.
9. The photovoltaic device of claim 1 , wherein the fatty acid modified epoxy acrylate and/or methacrylate monomer(s) or oligomer(s) are used at a concentration of from about 0.1% to about 30%.
10. The photovoltaic device of claim 1 , wherein the fatty acid modified polyester acrylate and/or methacrylate monomer(s) or oligomer(s) are used at a concentration of from about 0.1% to about 30%.
11. The photovoltaic device of claim 1 , wherein the combination of (i) fatty acid modified epoxy acrylate and/or methacrylate monomer(s) or oligomer(s), and (ii) fatty acid modified polyester acrylate and/or methacrylate monomer(s) or oligomer(s) are used at a concentration of from about 0.1% to about 30%.
12. The photovoltaic device of claim 1 , wherein the composition further comprises an epoxy triacrylate oligomer.
13. The photovoltaic device of claim 12 , wherein the epoxy triacrylate oligomer is aliphatic.
14. The photovoltaic device of claim 12 , wherein the epoxy triacrylate oligomer is used at a concentration of from about 0.1% to about 25%.
15. The photovoltaic device of claim 1 , wherein the silver particles comprise flakes.
16. The photovoltaic device of claim 1 , wherein the silver particles have a particle size of about 0.1 to about 20 microns.
17. The photovoltaic device of claim 1 , wherein the composition is solvent-free.
18. The photovoltaic device of claim 1 , wherein the photovoltaic device is formed of a silicon substrate having a front side and a backside, and the plurality of layers are deposited on at least one of the front side or backside.
19. The photovoltaic device of claim 18 , wherein the front side of the silicon substrate has a layer formed of a p-type/i-type material and the electrically conductive member is disposed on the layer.
20. The photovoltaic device of claim 18 , wherein the front side of the silicon substrate has an anti-reflective coating between the layer and the electrically conductive member.
21. The photovoltaic device of claim 18 , wherein the backside of the silicon substrate has a layer formed of an n-type or i-type material and the electrically conductive member is disposed on the layer.
22. The photovoltaic device of claim 19 , wherein the backside of the silicon substrate has a back contact layer formed of aluminum applied between the layer and the electrically conductive member.
23. The device of claim 1 wherein the electrically conductive member exhibits a contact resistivity of less than 20 ohm·cm 2 .