Solar cell and method of manufacturing the same
A solar cell and a method of manufacturing the same are disclosed. The solar cell includes a substrate of a first conductive type; an emitter layer of a second conductive type opposite the first conductive type on the substrate; a first electrode electrically connected to the emitter layer; a passivation layer on the substrate; a second electrode conductive layer on the passivation layer, the second electrode conductive layer including at least one second electrode electrically connected to the substrate through the passivation layer; and a second electrode current collector electrically connected to the second electrode conductive layer.
1 . A method of manufacturing a solar cell, comprising:
providing a substrate of a first conductive type;
forming an emitter layer of a second conductive type opposite the first conductive type on a front surface and a rear surface of the substrate and removing the emitter layer on the rear surface of the substrate;
forming an anti-reflection layer on the emitter layer on the front surface;
forming a rear passivation layer on the rear surface of the substrate;
coating a first paste on the anti-reflection layer to form a front electrode and front electrode current collector pattern;
coating a second paste that includes a metal on the rear passivation layer to form a rear electrode conductive pattern having a plurality of openings on the rear passivation layer, wherein the plurality of openings expose the rear passivation layer;
coating a third paste on the rear passivation layer that is exposed by the plurality of openings of the rear electrode conductive pattern to form a plurality of rear electrode current collector patterns;
irradiating a laser beam onto one or more portions of the rear electrode conductive pattern to form a molten mixture of material of the second paste that includes a metal, material of the rear passivation layer, and material of the substrate at the one or more portions of the rear electrode conductive pattern, wherein, in a plan view, the one or more portions of the rear electrode conductive pattern that is irradiated do not overlap the plurality of rear electrode current collector patterns; and
performing a firing process on the front electrode and front electrode current collector pattern, the rear electrode conductive pattern, the molten mixture, and the plurality of rear electrode current collector patterns,
wherein, as a result of the firing process, the front electrode and front electrode current collector pattern are converted to a plurality of first electrodes and a plurality of front electrode current collectors, the rear electrode conductive pattern is converted to a rear electrode conductive layer, the molten mixture is converted to a plurality of rear electrodes and a plurality of back surface field layers, the plurality of rear electrodes are located between the rear electrode conductive layer and the plurality of back surface field layers, and the plurality of rear electrode current collector patterns are converted to a plurality of rear electrode current collectors, and wherein the firing process simultaneously forms the rear electrode conductive layer, the plurality of rear electrodes, the plurality of back surface field layers, and the plurality of rear electrode current collectors.
2 . The method of claim 1 , wherein the first paste and the third paste both contain silver (Ag), and the second paste contains aluminum (Al).
3 . The method of claim 2 , wherein the front electrode and front electrode current collector pattern further contains lead (Pb), whereas the rear electrode conductive pattern and the plurality of rear electrode current collector patterns do not contain Pb.
4 . The method of claim 1 , wherein the first paste, the second paste, and the third paste are coated using a screen printing method and then are dried to form the front electrode and front electrode current collector pattern, the rear electrode conductive pattern, and the plurality of rear electrode current collector patterns, respectively.
5 . The method of claim 4 , wherein the first paste, the second paste, and the third paste are dried at a temperature lower than a temperature of the firing process.
6 . The method of claim 1 , wherein a temperature of the firing process is about 750° C. to 800° C.
7 . The method of claim 1 , wherein the front electrode and front electrode current collector pattern is spaced apart from the emitter layer by the anti-reflection layer before the firing process, and the plurality of first electrodes and the plurality of front electrode current collectors pass through the anti-reflection layer and in direct contact with the emitter layer after the firing process.
8 . The method of claim 7 , wherein the plurality of rear electrode current collector patterns are spaced apart from the substrate by the rear passivation layer before the firing process, and the plurality of rear electrode current collectors are spaced apart from the substrate by the rear passivation layer after the firing process.
9 . The method of claim 7 , wherein a portion of the rear electrode conductive pattern that excludes the molten mixture is spaced apart from the substrate by the rear passivation layer before the firing process, and a portion of the rear electrode conductive layer that excludes the plurality of rear electrodes is spaced apart from the substrate by the rear passivation layer after the firing process.
10 . The method of claim 1 , wherein an entire front surface of the plurality of rear electrode current collectors are in direct contact with a rear surface of the rear passivation layer.
11 . The method of claim 1 , wherein the third paste is further coated on a portion of the rear electrode conductive pattern, and, after the firing process, an overlapped width of the rear electrode conductive layer and each rear electrode current collector of the plurality of rear electrode current collectors is approximately 0.1 mm to 1 mm.
12 . The method of claim 1 , wherein the plurality of back surface field layers are spaced apart from each other, and the plurality of rear electrodes are spaced apart from each other and the plurality of rear electrodes are physically connected to the rear electrode conductive layer.
13 . The method of claim 12 , wherein the plurality of rear electrodes are arranged in rows, and each first electrode has a stripe shape and overlaps a row of rear electrodes.
14 . The method of claim 1 , wherein, in the plan view, the plurality of rear electrodes do not overlap the plurality of rear electrode current collectors.