Solar cell and method for manufacturing the same
A solar cell includes a substrate of a first conductive type, a first doped region positioned at a first surface of the substrate and contains impurities of a second conductive type different from the first conductive type, and a first electrode part electrically connected to the first doped region. The first electrode part includes a thermosetting resin, and first and second conductive particles distributed in the thermosetting resin. The second conductive particles have a work function greater than the first conductive particles and form silicide at an interface contacting the first doped region.
1. A solar cell comprising:
a substrate of a first conductive type;
a first doped region positioned at a first surface of the substrate and contains impurities of a second conductive type different from the first conductive type;
a first dielectric layer formed on the first doped region and having a plurality of first openings;
a first electrode part electrically connected to the first doped region through the plurality of first openings of the first dielectric layer and formed by performing a thermal process on an electrode paste including a thermosetting resin, which is cured at a temperature of 230° C. to 260° C. to act as a binder, and silver (Ag) and nickel (Ni) particles distributed in the thermosetting resin,
wherein, after curing, both silver and nickel particles are present at an interface portion of the first electrode part; and
a nickel silicide positioned at an interface of the first doped region in contact with the nickel particles present at the interface portion of the first electrode part,
wherein the nickel silicide is formed by heating the substrate at a temperature of 350° C. to 400° C. in an atmosphere of an inert gas,
wherein the nickel particles are 15 wt % to 25 wt % based on the total weight of the silver particles and the nickel particles, and
wherein the thermosetting resin includes a monomer-based epoxy resin or an acrylic resin.
2. The solar cell of claim 1 , wherein a size of a nickel particle is about 2 μm to 10 μm.
3. The solar cell of claim 1 , wherein the first doped region is formed as an emitter region.
4. The solar cell of claim 1 , wherein the first electrode part includes a plurality of first finger electrodes extending in a first direction and a plurality of first bus bar electrodes extending in a second direction crossing the first finger electrodes.
5. The solar cell of claim 1 , further comprising:
a second doped region positioned at a second surface opposite the first surface of the substrate and contains impurities of the first conductive type at a concentration higher than the substrate;
a second dielectric layer formed on the second doped region and having a plurality of second openings; and
a second electrode part electrically connected to the second doped region through the plurality of second openings of the second dielectric layer,
wherein the second electrode part includes the Ag particles, the Ni particles, and the thermosetting resin, and
a nickel silicide is positioned at the second doped region in contact with the nickel particles.
6. The solar cell of claim 5 , wherein the second doped region is formed as a back surface field region.
7. The solar cell of claim 5 , wherein the second electrode part includes a plurality of second finger electrodes extending in a first direction and a plurality of second bus bar electrodes extending in a second direction crossing the second finger electrodes.