Photovoltaic devices with electroplated metal grids
One embodiment of the present invention provides a solar cell. The solar cell includes a photovoltaic structure and a front-side metal grid situated above the photovoltaic structure. The front-side metal grid also includes one or more electroplated metal layers. The front-side metal grid includes one or more finger lines, and each end of a respective finger line is coupled to a corresponding end of an adjacent finger line via an additional metal line, thus ensuring that the respective finger line has no open end.
1. A metallic grid positioned on a photovoltaic structure, the metallic grid comprising:
a first finger line positioned on a first surface of the photovoltaic structure;
a second finger line positioned on the first surface of the photovoltaic structure, wherein the second finger line is substantially parallel to the first finger line; and
a metallic line connecting an end of the first finger line to an adjacent end of the second finger line;
wherein a portion of the first finger line in a vicinity of an intersection between the first finger line and the metallic line is wider than a center portion of the first finger line.
2. The metallic grid of claim 1 , wherein the metallic line is wider than at least a portion of the first or second finger line.
3. The metallic grid of claim 1 , wherein the intersection between the metallic line and the first finger line is rounded or chamfered.
4. The metallic grid of claim 1 , wherein the first finger line comprises a metallic adhesive layer in direct contact with the photovoltaic structure, and wherein the metal adhesive layer comprises at least one of: Cu, Al, Co, W, Cr, Mo, Ni, Ti, Ta, titanium nitride, titanium tungsten, titanium silicide, titanium silicon nitride, tantalum nitride, tantalum silicon nitride, nickel vanadium, tungsten nitride, or their combinations.
5. The metallic grid of claim 4 , wherein the metallic adhesive layer is formed using a physical vapor deposition technique directly onto a transparent conductive oxide layer of the photovoltaic structure.
6. The metallic grid of claim 4 , wherein the first finger line further comprises an electroplated metallic layer and a metallic seed layer, wherein the metallic seed layer is positioned between the electroplated metallic layer and the metallic adhesive layer.
7. The metallic grid of claim 1 , wherein the first finger line comprises at least one of:
a Cu layer;
an Ag layer; or
a Sn layer.
8. The metallic grid of claim 1 , wherein the portion of the first finger line in the vicinity of the intersection is at least 20% wider than the center portion of the first finger line.
9. The metallic grid of claim 1 , wherein a length of the widened portion of the first finger line is between 1 and 30 mm.
10. The metallic grid of claim 1 , wherein a width of the intersection is 0.2 mm or less.
11. A metal grid on a surface of a photovoltaic structure, the grid comprising:
a busbar positioned on the surface of the photovoltaic structure;
a first finger line on the surface of the photovoltaic structure and substantially orthogonal to the busbar;
a second finger line on the surface of the photovoltaic structure and substantially orthogonal to the busbar;
a third finger line on the surface of the photovoltaic structure and substantially orthogonal to the busbar; and
a connecting metal line, wherein the connecting metal line electrically connects the first, second and the third finger lines, and wherein a portion of the first finger line in a vicinity of an intersection between the first finger line and the connecting metal line is wider than a center portion of the first finger line.
12. The metal grid of claim 11 , wherein the connecting metal line is wider than at least a portion of the first finger line.
13. The metal grid of claim 11 , wherein the intersection between the connecting metal line and the first finger line is rounded or chamfered.
14. The metal grid of claim 11 , wherein the first finger line comprises at least one of:
a Cu layer;
an Ag layer; or
a Sn layer.
15. The metal grid of claim 11 , wherein the first finger line comprises a metallic adhesive layer in direct contact with the photovoltaic structure, and wherein the metal adhesive layer comprises at least one of: Cu, Al, Co, W, Cr, Mo, Ni, Ti, Ta, titanium nitride, titanium tungsten, titanium silicide, titanium silicon nitride, tantalum nitride, tantalum silicon nitride, nickel vanadium, tungsten nitride, or their combinations.
16. The metal grid of claim 15 , wherein the metallic adhesive layer is formed using a physical vapor deposition technique directly onto a transparent conductive oxide layer of the photovoltaic structure.
17. The metal grid of claim 15 , wherein the first finger line further comprises an electroplated metallic layer and a metallic seed layer, wherein the metallic seed layer is positioned between the electroplated metallic layer and the metallic adhesive layer.
18. The metal grid of claim 11 , wherein the portion of the first finger line in the vicinity of the intersection is at least 20% wider than the center portion of the first finger line.
19. The metal grid of claim 11 , wherein a length of the widened portion of the first finger line is between 1 and 30 mm.
20. The metal grid of claim 11 , wherein a width of the intersection is 0.2 mm or less.