Multilayer thin-film back contact system for flexible photovoltaic devices on polymer substrates
View Patent ↗A polymer substrate and back contact structure for a photovoltaic element, and a photovoltaic element include a CIGS photovoltaic structure, a polymer substrate having a device side at which the photovoltaic element can be located and a back side opposite the device side. A layer of dielectric is optionally formed at the back side of the polymer substrate. A metal structure is formed at the device side of the polymer substrate.
1. A photovoltaic element, comprising:
a polymer substrate having opposing a device and a back side;
at least one stress-matching layer disposed on the back side of the polymer substrate, wherein said stress-matching layer comprises a dielectric layer;
a metal structure disposed on the device side of the polymer substrate, the metal structure comprising:
a copper-based layer disposed on the device side of the polymer substrate, and
a molybdenum-based cap layer disposed on the copper-based layer;
a Copper-Indium-Gallium-Selenide (CIGS) photovoltaic structure disposed on the molybdenum-based cap layer.
2. The photovoltaic element of claim 1 , the molybdenum-based cap layer comprising molybdenum having a density of at least 85% of bulk density of molybdenum.
3. The photovoltaic element of claim 1 , the molybdenum-based cap layer comprising molybdenum nitride, molybdenum oxide, or molybdenum oxynitride.
4. The photovoltaic element of claim 1 , the molybdenum-based cap layer comprising a molybdenum nitride, a molybdenum oxide, or a molybdenum oxynitride sublayer disposed on the copper-based layer, and a molybdenum sublayer disposed on the molybdenum nitride, molybdenum oxide, or molybdenum oxynitride sublayer.
5. The photovoltaic element of claim 1 , the metal structure further including an aluminum-based barrier layer disposed on the copper-based layer, such that the aluminum-based barrier layer is disposed between the copper-based layer and the molybdenum-based cap layer.
6. The photovoltaic element of claim 5 , the copper-based layer having a thickness of at least 50 nanometers.
7. The photovoltaic element of claim 6 , the aluminum-based barrier layer having a thickness of at least 10 nanometers.
8. The photovoltaic element of claim 5 , a combined thickness of the copper-based layer and the aluminum-based barrier layer being at least 100 nanometers.
9. The photovoltaic element of claim 5 , the molybdenum-based cap layer having a thickness of at least 20 nanometers but less than 200 nanometers.
10. The photovoltaic element of claim 5 , the aluminum-based barrier layer comprising aluminum and copper.
11. The photovoltaic element of claim 10 , the molybdenum-based cap layer comprising a molybdenum nitride, molybdenum oxide, or molybdenum oxynitride sublayer disposed on the aluminum-based barrier layer, and a molybdenum sublayer disposed on the molybdenum nitride, molybdenum oxide, or molybdenum oxynitride sublayer.
12. The photovoltaic element of claim 5 , the copper-based layer being formed of copper.
13. The photovoltaic element of claim 1 , the copper-based layer being formed of copper.
14. The photovoltaic element of claim 1 , the copper-based layer being formed of brass.
15. The photovoltaic element of claim 14 , the brass of the copper-based layer being a copper-aluminum alloy.
16. The photovoltaic element of claim 14 , the brass of the copper-based layer being a copper-manganese alloy.
17. The photovoltaic element of claim 14 , the molybdenum-based cap layer comprising molybdenum having a density of at least 85% of bulk density of molybdenum.
18. The photovoltaic element of claim 14 , the molybdenum-based cap layer comprising molybdenum oxynitride.
19. The photovoltaic element of claim 14 , molybdenum-based cap layer comprising a molybdenum oxynitride sublayer disposed on the copper-based layer, and a molybdenum sublayer disposed on the molybdenum oxynitride sublayer.
20. A method for forming a photovoltaic element, comprising:
disposing a dielectric layer on a back side of a polymer substrate;
disposing a copper-based layer on a device side of the polymer substrate, the device side being opposite of the back side;
disposing a molybdenum-based cap layer on the copper-based layer; and
disposing a CIGS photovoltaic structure on the molybdenum-based cap layer.
21. The method of claim 20 , disposing the molybdenum-based cap layer comprising disposing molybdenum on the copper-based layer using a vacuum-based sputter deposition process at a pressure of less than 20 millitorr.
22. The method of claim 20 , disposing the molybdenum-based cap layer comprising:
disposing a molybdenum nitride, molybdenum oxide, or molybdenum oxynitride sublayer on the copper-based layer; and
disposing a molybdenum sublayer on the molybdenum nitride, molybdenum oxide, or molybdenum oxynitride sublayer.
23. The method of claim 20 , further comprising disposing an aluminum-based barrier layer on the copper-based layer before disposing the molybdenum-based cap layer, such that the aluminum-based barrier layer is disposed between the copper-based layer and the molybdenum-based cap layer.
24. The method of claim 23 , disposing the aluminum-based barrier layer comprising disposing aluminum and copper on the copper-based layer.
25. The method of claim 23 , disposing the molybdenum-based cap layer comprising:
disposing a molybdenum oxynitride sublayer on the aluminum-based barrier layer; and
disposing a molybdenum sublayer on the molybdenum oxynitride sublayer.
26. The method of claim 23 , further comprising, before disposing the CIGS photovoltaic structure on the molybdenum-based cap layer, thermally annealing the copper-based layer, the aluminum-based barrier layer, and the molybdenum-based cap layer;
disposing the molybdenum-based cap layer comprising:
disposing a first cap sublayer comprising: molybdenum nitride, molybdenum oxide, or molybdenum oxynitride sublayer on the copper-based layer; and
disposing a molybdenum sublayer on said first cap sublayer.
27. The method of claim 26 , thermally annealing being performed in an inert atmosphere and/or in a vacuum.
28. The method of claim 20 , disposing the copper-based layer comprising disposing brass on the device side of the polymer substrate.
29. The method of claim 28 , disposing brass on the device side of the polymer substrate comprising disposing a copper-aluminum alloy on the device side of the polymer substrate.
30. The method of claim 28 , disposing brass on the device side of the polymer substrate comprising disposing a copper-manganese alloy.
31. The method of claim 28 , disposing the molybdenum-based cap layer comprising disposing molybdenum on the copper-based layer using a vacuum-based sputter deposition process at a pressure of less than 20 millitorr.
32. The method of claim 28 , disposing the molybdenum-based cap layer comprising disposing molybdenum and oxygen on the copper-based layer.
33. The method of claim 32 , further comprising, before disposing the CIGS photovoltaic structure on the molybdenum-based cap layer, thermally annealing the copper-based layer and the molybdenum-based cap layer in an inert atmosphere and/or in a vacuum.
34. The method of claim 28 , disposing the molybdenum-based cap layer comprising:
disposing a molybdenum oxynitride sublayer on the copper-based layer; and
disposing a molybdenum sublayer on the molybdenum oxynitride sublayer.
35. The method of claim 34 , further comprising, before disposing the CIGS photovoltaic structure on the molybdenum-based cap layer, thermally annealing the copper-based layer and the molybdenum-based cap layer in an inert atmosphere and/or in a vacuum.
36. The method of claim 28 , further comprising, before disposing the CIGS photovoltaic structure on the molybdenum-based cap layer, thermally annealing the copper-based layer and the molybdenum-based cap layer.
37. The method of claim 36 , thermally annealing being performed in an atmosphere including oxygen.
38. A photovoltaic element, comprising:
a polymer substrate having opposing a device and a back side;
a metal structure disposed on the device side of the polymer substrate, the metal structure comprising:
a copper-based layer disposed on the device side of the polymer substrate, and
a molybdenum-based cap layer disposed on the copper-based layer;
a Copper-Indium-Gallium-Selenide (CIGS) photovoltaic structure disposed on the molybdenum-based cap layer.
39. The photovoltaic element of claim 38 , further comprising:
at least one stress-matching layer disposed on the back side of the polymer substrate.
40. The photovoltaic element of claim 39 , wherein said stress-matching layer comprises a dielectric layer.
41. A method for forming a photovoltaic element, comprising:
disposing a copper-based layer on a device side of the polymer substrate, the device side being opposite of a back side;
disposing a molybdenum-based cap layer on the copper-based layer; and
disposing a CIGS photovoltaic structure on the molybdenum-based cap layer.
42. The method of claim 41 , further comprising:
disposing at least one stress-matching layer disposed on the back side of the polymer substrate.
43. The photovoltaic element of claim 42 , wherein said stress-matching layer comprises a dielectric layer.
44. A method for forming a photovoltaic element, comprising:
disposing an aluminum-based layer on a device side of a flexible substrate, the device side being opposite of the back side;
disposing a molybdenum-based cap layer on the aluminum-based layer, disposing the molybdenum-based cap layer comprising:
disposing a molybdenum nitride, molybdenum oxide, or molybdenum oxynitride sublayer on the aluminum-based layer; and
disposing a Copper-Indium-Gallium-Selenide (CIGS) photovoltaic structure on the molybdenum-based cap layer.
45. The method of claim 44 , disposing the molybdenum-based cap layer comprising disposing molybdenum on the aluminum-based layer using a vacuum-based sputter deposition process at a pressure of less than 20 millitorr.
46. The method of claim 44 , further comprising disposing a molybdenum sublayer on the molybdenum nitride, molybdenum oxide, or molybdenum oxynitride sublayer.
47. The method of claim 44 , further comprising, before disposing the CIGS photovoltaic structure on the molybdenum-based cap layer, thermally annealing the aluminum-based layer and the molybdenum-based cap layer.
48. The method of claim 47 , thermally annealing being performed in an inert atmosphere and/or in a vacuum.
49. The method of claim 47 , thermally annealing being performed in an atmosphere including oxygen.
50. The method of claim 44 , further comprising:
disposing at least one stress-matching layer on the back side of the flexible substrate.
51. The method of claim 50 , wherein said stress-matching layer comprises a dielectric layer.
52. The method of claim 46 , the molybdenum sublayer comprising molybdenum having a density of at least 85% of bulk density of molybdenum.
53. A photovoltaic element, comprising:
a polymer substrate having opposing a device and a back side;
a metal structure disposed on the device side of the polymer substrate, the metal structure comprising:
an aluminum-based layer disposed on the device side of the polymer substrate, and
a molybdenum-based cap layer disposed on the aluminum-based layer, the molybdenum-based cap layer comprising:
a molybdenum nitride, molybdenum oxide, or molybdenum oxynitride sublayer on the aluminum-based layer; and
a Copper-Indium-Gallium-Selenide (CIGS) photovoltaic structure disposed on the molybdenum-based cap layer.
54. The photovoltaic element of claim 53 , further comprising:
at least one stress-matching layer disposed on the back side of the polymer substrate.
55. The photovoltaic element of claim 54 , wherein said stress-matching layer comprises a dielectric layer.
56. The photovoltaic element of claim 53 , further comprising a molybdenum sublayer disposed on the molybdenum nitride, molybdenum oxide, or molybdenum oxynitride sublayer.
57. The photovoltaic element of claim 56 , the molybdenum sublayer comprising molybdenum having a density of at least 85% of bulk density of molybdenum.
58. The photovoltaic element of claim 53 , the aluminum-based layer having a thickness of at least 50 nanometers.
59. The photovoltaic element of claim 53 , the molybdenum-based cap layer having a thickness of at least 20 nanometers but less than 200 nanometers.
60. The photovoltaic element of claim 53 , a combined thickness of the aluminum-based layer and the molybdenum-based cap layer being at least 70 nanometers but less than 700 nanometers.
61. The photovoltaic element of claim 57 , the aluminum-based layer comprising aluminum and copper.
62. The photovoltaic element of claim 61 , a combined thickness of the aluminum-based layer, the molybdenum-based cap layer, and the molybdenum sublayer being at least 70 nanometers but less than 700 nanometers.