COMPOSITION FOR FORMING ELECTRODE FOR SOLAR CELL INCLUDING NANOTEXTURED SUBSTRATE, ELECTRODE PREPARED USING THE SAME AND SOLAR CELL INCLUDING ELECTRODE PREPARED USING THE SAME
A composition for electrodes of solar cells that include a nano-textured substrate and a solar cell including the electrode, the composition including a conductive powder; a glass frit; and an organic vehicle, wherein, when a particle size distribution curve is plotted in a graph with particle size of the conductive powder on the x-axis and fraction of conductive powder particles of corresponding diameter on the y-axis, the conductive powder satisfies Equations 1, 2, and 3.
1 . A composition for electrodes of solar cells that include a nano-textured substrate, the composition comprising:
a conductive powder;
a glass frit; and
an organic vehicle,
wherein, when a particle size distribution curve is plotted in a graph with particle size of the conductive powder on the x-axis and fraction of conductive powder particles of corresponding diameter on the y-axis, the conductive powder satisfies Equations 1, 2, and 3:
about 5%≤( S 2/ S 1)×100≤ about 65% [1]
about 1%≤( S 3/ S 1)×100≤ about 55% [2]
about 0.4%≤( S 4/ S 1)×100≤ about 45% [3]
wherein S 1 is a total area enclosed by the particle size distribution curve and the x-axis, S 2 is an area enclosed by the particle size distribution curve and the x-axis within the particle diameter range of greater than 0 μm and less than or equal to about 2.0 μm, S 3 is an area enclosed by the particle size distribution curve and the x-axis within the particle diameter range of greater than 0 μm and less than or equal to about 1.7 μm, and S 4 is an area enclosed by the particle size distribution curve and the x-axis within the particle diameter range of greater than 0 μm and less than or equal to about 1.3 μm.
2 . The composition as claimed in claim 1 , wherein the conductive powder satisfies Equation 4:
about 5%≤( S 5/ S 1)×100≤ about 40% [4]
wherein S 1 is the total area enclosed by the particle size distribution curve and the x-axis, and S 5 is an area enclosed by the particle size distribution curve and the x-axis within the particle diameter range of greater than about 1.3 μm and less than or equal to about 1.7 μm.
3 . The composition as claimed in claim 1 , wherein the conductive powder satisfies Equation 5:
about 5%≤( S 6/ S 1)×100≤ about 50% [5]
wherein S 1 is the total area enclosed by the particle size distribution curve and the x-axis, and S 6 is an area enclosed by the particle size distribution curve and the x-axis within the particle diameter range of greater than about 1.7 μm and less than or equal to about 2.0 μm.
4 . The composition as claimed in claim 1 , wherein the conductive powder satisfies Equation 6:
about 35%≤( S 7/ S 1)×100≤ about 95% [6]
wherein S 1 is the total area enclosed by the particle size distribution curve and the x-axis, and S 7 is an area enclosed by the particle size distribution curve and the x-axis within the particle diameter range of greater than about 2.0 μm.
5 . The composition as claimed in claim 1 , wherein the conductive powder includes silver powder.
6 . The composition as claimed in claim 1 , wherein the composition includes:
about 60 wt % to about 95 wt % of the conductive powder;
about 0.1 wt % to about 20 wt % of the glass frit; and
the organic vehicle.
7 . The composition as claimed in claim 1 , further comprising a dispersant, a thixotropic agent, a plasticizer, a viscosity stabilizer, an anti-foaming agent, a pigment, a UV stabilizer, an antioxidant, or a coupling agent.
8 . A solar cell, comprising:
a nano-textured substrate; and
an electrode on the nano-textured substrate,
wherein:
the nano-textured substrate includes a substrate having an average of 5 or more bumps having a height of about 50 nm or more per about 5 μm length in vertical section, and
the electrode is prepared from the composition as claimed in claim 1 .
9 . The solar cell as claimed in claim 8 , wherein an average maximum distance between a pair of adjacent bumps each having the height of about 50 nm or more per about 5 μm length in vertical section of the nano-textured substrate is greater than or equal to about 100 nm.
10 . The solar cell as claimed in claim 8 , wherein the conductive powder satisfies Equation 4:
about 5%≤( S 5/ S 1)×100≤ about 40% [4]
wherein S 1 is the total area enclosed by the particle size distribution curve and the x-axis, and S 5 is an area enclosed by the particle size distribution curve and the x-axis within the particle diameter range of greater than about 1.3 μm and less than or equal to about 1.7 μm.
11 . The solar cell as claimed in claim 8 , wherein the conductive powder satisfies Equation 5:
about 5%≤( S 6/ S 1)×100≤ about 50% [5]
wherein S 1 is the total area enclosed by the particle size distribution curve and the x-axis, and S 6 is an area enclosed by the particle size distribution curve and the x-axis within the particle diameter range of greater than about 1.7 μm and less than or equal to about 2.0 μm.
12 . The solar cell as claimed in claim 8 , wherein the conductive powder satisfies Equation 6:
about 35%≤( S 7/ S 1)×100≤ about 95% [6]
wherein S 1 is the total area enclosed by the particle size distribution curve and the x-axis, and S 7 is an area enclosed by the particle size distribution curve and the x-axis within the particle diameter range of greater than about 2.0 μm.
13 . The solar cell as claimed in claim 8 , wherein the conductive powder includes silver powder.
14 . The solar cell as claimed in claim 8 , wherein the composition includes:
about 60 wt % to about 95 wt % of the conductive powder;
about 0.1 wt % to about 20 wt % of the glass frit; and
the organic vehicle.
15 . The solar cell as claimed in claim 8 , wherein the composition further includes a dispersant, a thixotropic agent, a plasticizer, a viscosity stabilizer, an anti-foaming agent, a pigment, a UV stabilizer, an antioxidant, or a coupling agent.