Solar cell and method for manufacturing the same, and solar cell panel
Discussed is a solar cell including a semiconductor substrate, a conductive region disposed in the semiconductor substrate or over the semiconductor substrate, and an electrode electrically connected to the conductive region. The electrode includes a first electrode part and a second electrode part disposed over the first electrode part. The second electrode part includes a particle connection layer formed by connecting a plurality of particles including a first metal and a cover layer including a second metal different from the first metal and covering at least the outside surface of the particle connection layer.
1. A solar cell comprising:
a semiconductor substrate;
a conductive region provided in the semiconductor substrate or on the semiconductor substrate; and
an electrode electrically connected to the conductive region,
wherein the electrode comprises a first electrode part and a second electrode part, the second electrode part being provided over the first electrode part, and
wherein the second electrode part comprises:
a particle connection layer formed by connecting a plurality of particles, each particle including a first metal, and
a cover layer including a second metal different from the first metal and covering at least an outside surface of the particle connection layer,
wherein the first electrode part comprises:
a first electrode layer including a refractory metal;
a second electrode layer provided on the first electrode layer and having lower resistance than the first electrode layer;
a third electrode layer formed on the second electrode layer and acting as a diffusion barrier; and
a fourth electrode layer provided on the third electrode layer and including tin or a nickel-vanadium alloy, and
wherein the second electrode part is provided to contact the fourth electrode layer.
2. The solar cell of claim 1 , wherein the first metal has a resistance equal to or lower than a material of the first electrode part, and
wherein the second metal has a smaller ionization energy than the first metal or a lower reactivity of a metal than the first metal to prevent an oxidization of the first metal.
3. The solar cell of claim 2 , wherein the second metal comprises a solder material having a lower melting point than the first metal.
4. The solar cell of claim 1 , wherein the first metal comprises at least one of copper, silver, aluminum, or gold, and
wherein the second metal comprises at least one of tin, chrome, manganese, molybdenum or nickel.
5. The solar cell of claim 4 , wherein the first metal comprises copper, and
wherein the second metal comprises tin.
6. The solar cell of claim 1 , wherein the second electrode part configures an outermost layer of the electrode, and
wherein the second electrode part has lower density than the first electrode part.
7. The solar cell of claim 1 , wherein a ratio of a thickness of the second electrode part to a thickness of the first electrode part is about 10 or more.
8. The solar cell of claim 7 , wherein a first thickness of the particle connection layer is greater than a second thickness of the cover layer in a portion provided on the outside surface of the particle connection layer.
9. The solar cell of claim 8 , wherein a ratio of the second thickness to the first thickness is 0.04 to 0.2.
10. The solar cell of claim 1 , wherein a thickness of the cover layer is greater than a surface roughness of the outside surface of the particle connection layer.
11. The solar cell of claim 1 , wherein a surface roughness of an outside surface of the cover layer is smaller than a surface roughness of the outside surface of the particle connection layer.
12. The solar cell of claim 1 , wherein a width of the second electrode part is equal to or smaller than a width of the first electrode part.
13. The solar cell of claim 12 , wherein the second electrode part is formed on a surface of the first electrode part provided opposite the semiconductor substrate and is not formed on a side of the first electrode part in a direction intersecting the semiconductor substrate.
14. The solar cell of claim 1 , wherein the first electrode layer includes titanium,
wherein the second electrode layer includes aluminum,
wherein the third electrode layer includes titanium, and
wherein the fourth electrode layer includes the nickel-vanadium alloy.
15. The solar cell of claim 1 , wherein the conductive region comprises:
a first conductive region provided on one surface of the semiconductor substrate and having a first conductive type, and a second conductive region provided in a position different from a position of the first conductive region on the one surface of the semiconductor substrate, the second conductive region having a second conductive type,
wherein the electrode comprises a first electrode connected to the first conductive region and a second electrode connected to the second conductive region, and
wherein at least one of the first electrode and the second electrode comprises the first electrode part and the second electrode part.