TWM462446U - Electrode structure and solar cell using the same - Google Patents

Abstract

A solar cell including a substrate, a plurality of first electrodes, a second electrode, and a third electrode is provided. A first surface of the substrate has an edge region extending along a first direction. The first electrodes disposed over the first surface are spaced and arranged in parallel along a second direction, wherein a part of the first electrodes is disposed within the edge region. The first direction and the second direction are not parallel. The second electrode, extending along the second direction over the first surface, has a top end disposed between two of the first electrodes within the edge region. The third electrode, extending alone a third direction over the first surface, connects the top end of the second electrode and the farthest first electrode within the edge region away from the top end of the second electrode, wherein the third direction and the first direction are not parallel. An electrode structure of the solar cell is also provided.

Description

Electrode structure and solar cell suitable for the same

This creation relates to an electrode structure, and more particularly to an electrode structure that can be applied to a solar cell.

Energy depletion is becoming more and more serious, and the environmental awareness of various countries is rising. We do not pay much attention to the development of renewable energy, especially the problem that solar energy has no energy exhaustion. Therefore, solar cells have received great attention, and in pursuit of photoelectric conversion efficiency, the cost is also reduced. Become an important goal of research and development.

Referring to FIG. 1, FIG. 1 is a cross-sectional view of a conventional solar cell 100. The conventional solar cell 100 includes a semiconductor substrate 10 having a PN junction region 15 therein. When light is irradiated to the front surface 10a of the substrate 10, the semiconductor element For example, electrons and holes of the germanium atom are separated from each other, and an internal electric field is formed in the PN junction region 15 to generate a drift current. In order to conduct the current into which the solar light energy is converted, the electrode main gate line 12 and the electrode sub-gate line 11 are disposed as anode electrodes on the front surface 10a of the semiconductor substrate 10, and the cathode electrode 14 is disposed on the back surface 10b of the substrate 10. The sub-gate line 11 is densely distributed above the front surface 10a, and is therefore also referred to as a finger electrode, and the main gate line 12 serves as a bus bar for conducting currents of the sub-gate line 11. However, the area where the densely distributed sub-gate lines 11 are located causes the light-shielding rate of the solar cell 100 to rise. Therefore, the finer the line width of the sub-gate line 11 is, the more the light-shielding rate can be lowered, and the main gate line 12 is a collecting current whose line width is larger than that of the sub-gate. Line 11 is wide.

The prior art uses a screen printing technique to print an electrode material to the front surface 10a of the substrate 10 in accordance with a designed printing pattern, and uses high temperature sintering to form a good ohmic contact between the electrode material and the semiconductor substrate 10. Since metal has good electrical conductivity, it is widely used as an electrode material of a solar cell, particularly silver, and the content of silver is usually 90% of the electrode material. However, if the main gate line 12 and the thin sub-gate line 11 having a large line width are composed of the same proportion of silver content, the cost is too high. Therefore, the current technology has evolved from one printing to the second printing, and the silver of the sub-gate line 11 The content is constant, and the silver content of the main grid line 12 can be reduced to 60%, and the electrode materials of different silver contents are printed onto the front surface 10a of the substrate 10 through the first screen printing process S1 and the second screen printing process S2, respectively. As shown in Figure 2, the cost can be greatly reduced accordingly.

However, the Applicant has found that the screen used for printing is gradually deformed after about 5,000 printings, so when performing secondary printing, it is highly likely that the joint of the sub-gate line 11 of the edge and the main gate line 12 is as shown in FIG. An abnormality occurs, as indicated by a broken line B1, the main gate line 12 protrudes from the edge of the sub-gate line 11, and the main gate line 12 shown by the broken line B2 is not bonded to the sub-gate line 11 of the edge, not only the edge pair The current of the gate line 11 is turned on, and the problem of misalignment of the joint is also detrimental to the aesthetics. Therefore, only a new screen can be replaced to improve the problem, but it is costly. In addition, if the offset of the screen printing is offset, an abnormality may occur in the joint. In view of this, how to effectively solve the appearance of the abnormal electrode bonding of the front side of the solar cell under the condition of reducing the cost is the development of the present invention.

One of the aims of the present invention is to provide a solar cell which can save the manufacturing cost and effectively solve the appearance of abnormality of the front electrode of the solar cell. To achieve the foregoing objective, a solar cell according to an embodiment of the present invention includes a semiconductor substrate having a first surface and a second surface opposite to the first surface, wherein the first surface has a side region extending along the first direction; The first electrodes are disposed above the first surface and electrically connected to the semiconductor substrate. The first electrodes are arranged in parallel along the second direction, wherein some of the first electrodes are located in the side regions, and the first The direction intersects with the second direction; the second electrode extends above the first surface in the second direction, Electrically contacting the first electrodes, and the top end of the second electrode is located between any two first electrodes in the side region; and the third electrode extends above the first surface in the third direction and is connected a first electrode of the second electrode and a first electrode of the side region farthest from the top end of the second electrode, wherein the third direction intersects the first direction, and the width of the second electrode is greater than the width of the first electrode.

In a solar cell according to an embodiment of the present invention, the width of the third electrode is larger than the width of the first electrodes.

In a solar cell according to an embodiment of the present invention, the width of the second electrode is greater than the width of the third electrode.

In a solar cell according to an embodiment of the present invention, the semiconductor substrate includes: an anti-reflection layer disposed on the first surface; a PN junction region disposed between the first surface and the second surface; and a fourth electrode disposed on the first surface On both sides, it is electrically connected to the semiconductor substrate.

In a solar cell according to an embodiment of the present invention, the first direction and the second direction are substantially perpendicular.

In a solar cell according to an embodiment of the present invention, the third direction and the second direction are substantially parallel.

The solar cell of one embodiment of the present invention further includes another third electrode extending above the first surface in the fourth direction and connecting the top end of the second electrode to the farthest side of the side electrode from the top end of the second electrode a first electrode, wherein the fourth direction intersects the first direction.

In a solar cell according to an embodiment of the present invention, the fourth direction is substantially parallel to the second direction or the third direction.

In a solar cell according to an embodiment of the present invention, the three or four of the first electrodes are located in the side regions.

One of the aims of the present invention is to provide an electrode structure which can save the manufacturing cost and effectively solve the appearance of abnormality of the front electrode of the solar cell. In order to achieve the above purpose, the electrode structure is suitable for a solar cell, the solar cell has a substrate, and the electrode structure is disposed on the base. Above the light receiving surface of the board, the light receiving surface has a side area extending along the first direction, and the electrode structure comprises a plurality of first electrodes arranged in parallel according to the second direction, wherein some of the first electrodes are located in the side area, And the first direction intersects with the second direction; the second electrode extends in the second direction and is electrically connected to the first electrodes, and the top end of the second electrode is located between any two first electrodes in the side region And at least one third electrode extending in a third direction, connecting the top end of the second electrode and the first electrode in the side region farthest from the top end of the second electrode, wherein the third direction intersects the first direction, and The width of the second electrode is greater than the width of the third electrode, and the width of the third electrode is greater than the width of the first electrodes.

10‧‧‧Semiconductor substrate

10a‧‧‧Semiconductor substrate front

10b‧‧‧Back of semiconductor substrate

100, 200‧‧‧ solar cells

11, 21‧‧‧electrode sub-gate line

12, 22‧‧‧electrode main grid line

14‧‧‧Cathode electrode

15‧‧‧P-N junction area

16‧‧‧Anti-reflective layer

31‧‧‧First electrode

32‧‧‧second electrode

33, 33a‧‧‧ third electrode

A1‧‧‧Side area

B1, B2, C1, C2, D1, D2‧‧‧ joints

S1, S2‧‧‧ screen printing program

X1, X2, X3, X4‧‧‧ directions

Figure 1 is a cross-sectional view of a conventional solar cell.

2 is an exploded top view of a front electrode structure of a conventional solar cell.

3 is a top view of a front electrode structure of a conventional solar cell.

Fig. 4 is an exploded top plan view showing the front electrode structure of the solar cell in the first embodiment of the present invention.

Figure 5 is a top plan view of the front electrode structure of the solar cell in the first embodiment of the present invention.

Fig. 6 is an exploded top plan view showing the front electrode structure of the solar cell in the second embodiment of the present invention.

Figure 7 is a top plan view of the front electrode structure of the solar cell in the second embodiment of the present invention.

Figure 8 is a top plan view of the front electrode structure of the solar cell in the third embodiment of the present invention.

Figure 9 is a cross-sectional view of a solar cell of a second embodiment of the present invention.

Please refer to FIG. 4. FIG. 4 is an exploded top view of the front electrode structure of the solar cell in the first embodiment of the present invention. In this embodiment, the applicant designs the top end of the main grid line 22 to be thin. When the long tip is joined to the edge sub-grid line 21, even if the alignment is not correct or the screen is deformed, the joints C1 and C2 are uneven, and the naked eye is observed with the conventional B1 and B2. Compared, it becomes less obvious (as shown in Figure 5).

In addition, the applicant provides a second embodiment of the present invention. Please refer to FIG. 6. FIG. 6 is an exploded top view of the front electrode structure of the solar cell in the second embodiment of the present invention. In the present embodiment, the front surface 10a of the semiconductor substrate 10, that is, the light receiving surface, has a side area A1 extending in the first direction X1. The first screen printing process S1 is performed, and the first conductive material is printed on the front surface 10a of the substrate 10 through the first screen pattern (not shown) to form a plurality of first electrodes 31 and third electrodes 33, wherein each The first electrodes 31 are all arranged along the first direction X1, and the first electrodes 31 are arranged in parallel along the second direction X2. The distance between the first electrodes 31 may be between 1300 micrometers and 2500 micrometers. A part of the first electrode 31 in the side area A1, for example, three or four first electrodes 31 are arranged in the side area A1. It is to be noted that the third electrode 33 is connected to the first electrode 31 of the edge of the side edge area A1 at one end, and the other end of the third electrode 33 is connected to any two of the first electrodes 31 of the side area A1. The first direction X1 intersects with the third direction X3, and may be substantially perpendicularly intersected. Therefore, the third electrode 33 is in direct contact with a portion of the first electrode 31 extending through the side area A1.

Next, the second screen printing process S2 is performed, and the second conductive material is printed to the front surface 10a of the substrate 10 through the second screen pattern (not shown) for forming the second electrode 32 extending in the second direction X2. The top end of the second electrode 32 is joined to the third electrode 33 between any two of the first electrodes 31 in the side area A1, and the second direction X2 intersects with the first direction X1, which may be vertically intersected in a solid state. The second electrode 32 is electrically connected to the semiconductor substrate 10 and electrically connected to a portion of the first electrode 31 in the side edge region A1 through the third electrode 33, thereby collecting a portion of the first electrode 31 in the side edge region A1. The current is while the second electrode 32 is in direct contact with the other first electrodes 31. It should be noted that the sequential relationship between the first screen printing program S1 and the second screen printing program S2 may be replaced. For example, after the second screen printing program S2 is performed, the first screen printing program S1 is performed. Additionally, alignment marks can be utilized to assist in the bonding of the second electrode 32 to the third electrode 33.

The first conductive material may be an electrode material containing a metal content of 90%. The first electrode 31 formed by screen printing may be a sub-gate line in the front electrode structure of the solar cell, and the second conductive material may be 60%. The metal content electrode material, the second electrode 32 formed by screen printing may be a main gate line in the front electrode structure, and the third electrode 33 formed by the first conductive material screen printing may be connected to the main gate line and the sub-gate line An area that is not in direct contact, which serves as a busbar for the side area A1. The metal used for the first conductive material and the second conductive material may be silver or copper. In addition, the width of the second electrode 32 may be greater than the width of the first electrode 31. For example, the width of the former may be 1500 micrometers, and the width of the latter may be 50 micrometers; and the width of the third electrode 33 may be between the first electrode 31 and the second electrode 32. Between the widths, for example 300 microns to 500 microns. Accordingly, the solar cell 200 of the second embodiment of the present invention is completed (as shown in FIG. 9). However, the relationship between the width of the first electrode 31, the second electrode 32, and the third electrode 33 is not limited to the above, as long as the effect of the effective on current can be achieved.

It should be noted that in this embodiment, the second direction X2 and the third direction X3 may be substantially parallel (as shown in FIG. 6), and one end of the third electrode 33 extends to the side area A1 according to the third direction X3. In the interval between any two of the first electrodes 31, according to this, even if the screen is deformed or the alignment is offset, the second electrode 32 and the third electrode 33 are aligned, and the upper and lower sides are offset within a reasonable range, as shown in the figure. 7 is shown by the broken lines D1 and D2, but the junction of the second electrode 32 and the third electrode 33 can still be located between the two first electrodes 31 in the side area A1, according to which the second electrode 32 is not caused. There is a convex or concave surface on the most edge first electrode 31, and it is difficult for the naked eye to recognize that the joint of D1 and D2 is not uniform in the interval of the first electrode 31, and the number of times of use of the screen can be increased. For example, more than 10,000 to 20,000 times, the alignment offset caused by the deformation may exceed a reasonable range. Accordingly, the second embodiment of the present invention can not only effectively solve the problem of appearance defects of the front electrode structure of the solar cell caused by the conventional secondary printing, but also avoid the cost of consuming too much screen. In addition, the third direction X3 may also slightly intersect with the second direction X2. As long as the second electrode 32 is aligned with the third electrode 33, it may be vertically and horizontally offset within a reasonable range, and may be joined.

Please refer to FIG. 8. FIG. 8 is a positive view of a solar cell according to a third embodiment of the present invention. Top view of the surface electrode structure. The solar cell 200 may include two or more third electrodes, such as the first electrode 31 having the third electrodes 33 and 33a simultaneously connecting the second electrode 32 and the edge of the side edge area A1, and the third electrode 33a may be The four directions X4 extend above the front surface 10a of the substrate 10, wherein the fourth direction X4 intersects the first direction X1, and the fourth direction X4 may be substantially parallel with the second direction X2 or the third direction X3, or may be opposite to the second direction The X2 or the third direction X3 slightly intersects, and if the second electrode 32 and the third electrode 33 are aligned, they are shifted up, down, left, and right within a reasonable range, and can be joined. According to this, it is also possible to effectively solve the appearance defect of the front electrode structure of the conventional solar cell while saving the process cost.

Referring to FIG. 9, the semiconductor substrate 10 of the solar cell 200 may include an anti-reflection layer 16 disposed on the front surface 10a of the substrate 10 to reduce reflection of sunlight, thereby increasing the light absorption rate of the solar cell.

31‧‧‧First electrode

32‧‧‧second electrode

33‧‧‧ third electrode

A1‧‧‧Side area

S1, S2‧‧‧ screen printing program

X1, X2, X3‧‧‧ directions

Claims (11)

A solar cell comprising: a semiconductor substrate having a first surface and a second surface opposite the first surface, wherein the first surface has a side region extending along a first direction; An electrode is disposed above the first surface and electrically connected to the semiconductor substrate, wherein the first electrodes are arranged in parallel along a second direction, wherein a portion of the first electrodes are located in the side region, and The first direction intersects the second direction; a second electrode extends above the first surface in the second direction, and is electrically connected to the first electrodes, and the top end of the second electrode is located at the first surface Between any two of the first electrodes in the side region; and a third electrode extending above the first surface in a third direction and connecting the top end of the second electrode and the side region The first electrode furthest from the top of the two electrodes, wherein the third direction intersects the first direction. The solar cell of claim 1, wherein the width of the second electrode is greater than the width of the first electrode. The solar cell of claim 1, wherein the third electrode has a width greater than a width of the first electrodes. The solar cell of claim 1, wherein the width of the second electrode is greater than the width of the third electrode. The solar cell of claim 1, wherein the semiconductor substrate comprises: An anti-reflection layer disposed on the first surface; a PN junction region disposed between the first surface and the second surface; and a fourth electrode disposed on the second surface and electrically connected to the semiconductor substrate Docked. The solar cell of claim 1, wherein the first direction is substantially perpendicular to the second direction. The solar cell of claim 1, wherein the third direction is substantially parallel to the second direction. The solar cell of claim 1, further comprising another third electrode extending above the first surface in a fourth direction and connecting the top end of the second electrode to the side region The first electrode furthest from the top end of the second electrode, wherein the fourth direction intersects the first direction. The solar cell of claim 8, wherein the fourth direction is substantially parallel to the second direction or the third direction. The solar cell of claim 1, wherein three or four of the first electrodes are located in the side region. An electrode structure is suitable for a solar cell, the solar cell has a substrate, the electrode structure is disposed above a light receiving surface of the substrate, and the light receiving surface has a side region extending along a first direction, the electrode structure comprises The plurality of first electrodes are arranged in parallel along a second direction, wherein a portion of the first electrodes are located in the side regions, and the first direction intersects the second direction; a second electrode extending in the second direction and electrically contacting the first electrodes, and a top end of the second electrode is located between any two of the first electrodes in the side region; and at least one The third electrode extends in a third direction and connects the top end of the second electrode and the first electrode in the side region farthest from the top end of the second electrode, wherein the third direction and the first direction Intersecting, and the width of the second electrode is greater than the width of the third electrode, and the width of the third electrode is greater than the width of the first electrodes.