SOLAR CELL AND METHOD FOR MANUFACTURING THE SAME
A solar cell includes a substrate, an emitter region including a lightly doped emitter region having a first sheet resistance and a heavily doped emitter region having a second sheet resistance less than the first sheet resistance, a first dielectric layer positioned on the emitter region, a first electrode including a first finger electrode positioned on the heavily doped emitter region in a first direction and a first bus bar electrode positioned on the lightly doped emitter region in a second direction, and a second electrode positioned on the substrate. The first finger electrode includes a seed layer contacting the heavily doped emitter region and a conductive metal layer formed on the seed layer, and the first bus bar electrode includes electrically conductive metal particles and a thermosetting resin.
1 . A solar cell comprising:
a substrate containing impurities of a first conductive type;
an emitter region positioned at a first surface of the substrate, the emitter region containing impurities of a second conductive type opposite the first conductive type and including a lightly doped emitter region having a first sheet resistance and a heavily doped emitter region having a second sheet resistance less than the first sheet resistance;
a first dielectric layer positioned on the emitter region;
a first electrode including a first finger electrode which is positioned on the heavily doped emitter region in a first direction, and a first bus bar electrode which is positioned on the lightly doped emitter region in a second direction; and
a second electrode which is positioned on a second surface of the substrate and is connected to the substrate,
wherein the first finger electrode includes a seed layer contacting the heavily doped emitter region and a conductive metal layer formed on the seed layer, and the first bus bar electrode includes electrically conductive metal particles and a thermosetting resin.
2 . The solar cell of claim 1 , wherein the first dielectric layer is positioned between the first bus bar electrode and the lightly doped emitter region.
3 . The solar cell of claim 1 , wherein the electrically conductive metal particles contain silver (Ag).
4 . The solar cell of claim 1 , wherein a size of each of the electrically conductive metal particles is equal to or less than about 1 μm.
5 . The solar cell of claim 1 , wherein the first bus bar electrode lacks a glass frit or includes a glass frit equal to or less than about 10% per unit volume of the first bus bar electrode.
6 . The solar cell of claim 1 , wherein the first bus bar electrode lacks a metal layer recrystallized at an interface between the first bus bar electrode and the emitter region.
7 . The solar cell of claim 1 , wherein the thermosetting resin includes a monomer-based epoxy resin or an acrylic resin.
8 . The solar cell of claim 1 , wherein the first finger electrode is a plated structure.
9 . The solar cell of claim 1 , wherein the seed layer contains a nickel-silicide of nickel (Ni) and silicon (Si), and the conductive metal layer contains at least one of tin (Sn), copper (Cu), and silver (Ag).
10 . The solar cell of claim 1 , wherein the lightly doped emitter region directly contacts the first dielectric layer, and the first bus bar electrode directly contacts the first dielectric layer.
11 . The solar cell of claim 1 , wherein the second electrode includes a second finger electrode positioned in the first direction and a second bus bar electrode positioned in the second direction crossing the first direction.
12 . The solar cell of claim 11 , wherein the second finger electrode includes a seed layer and a conductive metal layer formed on the seed layer.
13 . The solar cell of claim 11 , wherein the second bus bar electrode includes electrically conductive metal particles and a thermosetting resin.
14 . A method for manufacturing a solar cell comprising:
forming a lightly doped emitter region having a first sheet resistance at a first surface of a substrate;
forming a first dielectric layer on the lightly doped emitter region;
coating a dopant paste on the first dielectric layer and irradiating a laser beam onto the dopant paste to form a heavily doped emitter region having a second sheet resistance less than the first sheet resistance;
forming a first finger electrode on the heavily doped emitter region in a first direction and forming a first bus bar electrode on the lightly doped emitter region in a second direction to form a first electrode; and
forming a second electrode on a second surface of the substrate,
wherein the first finger electrode of the first electrode is formed using a plating method,
wherein the forming of the first bus bar electrode of the first electrode includes coating a bus bar paste including electrically conductive metal particles and a thermosetting resin and performing a predetermined temperature process on the bus bar paste.
15 . The method of claim 14 , wherein the predetermined temperature process of the bus bar paste is performed at about 300° C. to 350° C.
16 . The method of claim 14 , wherein when the predetermined temperature process is performed on the bus bar paste, the bus bar paste does not pass through the first dielectric layer.
17 . The method of claim 14 , wherein when the predetermined temperature process is performed on the bus bar paste, a recrystallized metal layer is not formed at an interface between the bus bar paste and the emitter region.
18 . The method of claim 14 , wherein a shape of the electrically conductive metal particles after performing the predetermined temperature process is the same as a shape of the electrically conductive metal particles before performing predetermined low temperature process.
19 . The method of claim 14 , wherein the bus bar paste lacks a glass frit or includes a glass frit equal to or less than about 10% per unit volume of the bus bar paste.
20 . The method of claim 14 , wherein the thermosetting resin includes a monomer-based epoxy resin or an acrylic resin.
21 . The method of claim 14 , wherein the first finger electrode includes a seed layer containing nickel (Ni) formed on the heavily doped emitter region and a conductive metal layer formed on the seed layer,
wherein when the predetermined temperature process is performed on the bus bar paste, a nickel-silicide layer generated by chemical bonding between nickel (Ni) and silicon (Si) of the heavily doped emitter region is formed on the seed layer of the first finger electrode.