JP2014013783A - Method of manufacturing solar cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of manufacturing a solar cell having highly accurate shape of electrodes.SOLUTION: A downstream-side end portion 21a1 of a first opening 21, which is a second opening-side end portion located closer to the other side of one direction y than to a second opening 22a, includes a first portion 23 and a second portion 24. The first portion 23 is tapered toward a second primary surface 20b side of a photoelectric conversion portion 10 side from a first primary surface 20a at the opposite side of the photoelectric conversion 10 of a printing plate 20. The second portion 24 is located closer to the photoelectric conversion portion 10 side than to the first portion 23. The second portion 24 has the same opening area as that at an apex of the first portion 23 at the photoelectric conversion portion 10 side.

Description

  The present invention relates to a method for manufacturing a solar cell.

  In recent years, solar cells have attracted a great deal of attention as an energy source with a low environmental load. A solar cell has a photoelectric conversion unit that generates carriers such as electrons and holes by receiving light, and an electrode that collects carriers generated in the photoelectric conversion unit. As an electrode for collecting the carrier, an electrode having a plurality of finger electrode portions and a bus bar that intersects with the plurality of finger electrode portions and electrically connects the plurality of finger electrode portions (hereinafter referred to as the electrodes) , "Comb-shaped electrode") is widely used.

  As a method for forming a comb-type electrode, for example, the following Patent Document 1 proposes a method of forming by screen printing. In Patent Document 1, as a screen printing plate for forming a comb-shaped electrode, among the openings for forming the finger electrodes, the width of one side portion of the connecting portion to the opening for forming the bus bar portion is larger than the width of the other side portion. A small screen printing version has been proposed. By using this screen printing plate to move the squeegee from the other side to the one side to perform electrode printing, it is possible to prevent the connection portion between the finger electrode portion and the bus bar portion from becoming thicker than the other portions. Is described in Patent Document 1.

Japanese Patent No. 4391803

  However, in the screen printing plate described in Patent Document 1, it is necessary to make a part of the opening for forming the finger electrode part narrower than the other part. The width of the narrow part becomes too small. For this reason, the paste does not pass through the narrow portion. Therefore, when the screen printing plate described in Patent Document 1 is used, there is a problem that it is not possible to suitably manufacture a solar cell in which the finger electrode portions are thinned in order to increase the photoelectric conversion efficiency.

  This invention is made | formed in view of this point, The objective is to provide the method which can manufacture a solar cell with the high shape precision of an electrode.

  The method for manufacturing a solar cell according to the present invention includes a photoelectric conversion unit and an electrode disposed on one main surface of the photoelectric conversion unit, the electrode extending in one direction, and the finger electrode unit electrically The present invention relates to a method of manufacturing a solar cell having a bus bar portion that is connected to the finger electrode portion and intersects the finger electrode portion. The method for manufacturing a solar cell according to the present invention includes a step of placing a printing plate on one main surface of a photoelectric conversion unit, a conductive paste on the printing plate, and a squeegee on the printing plate. Forming an electrode by moving from one side of the direction toward the other side. The printing plate has a first opening and a second opening. The first opening is an opening for forming the finger electrode portion. The second opening is an opening for forming the bus bar portion. The second opening intersects the first opening. The downstream end, which is the second opening side end of the downstream portion located on the other side in the one direction from the second opening of the first opening, includes the first portion and the second portion. Including. The first portion tapers from the first main surface opposite to the photoelectric conversion unit of the printing plate toward the second main surface side on the photoelectric conversion unit side. The second part is located closer to the photoelectric conversion unit than the first part. The second portion has an opening area equal to the opening area at the tip of the first portion on the photoelectric conversion unit side.

  ADVANTAGE OF THE INVENTION According to this invention, the method which can manufacture a solar cell with the high shape precision of an electrode can be provided.

1 is a schematic plan view of a solar cell according to an embodiment of the present invention. It is a schematic side view showing the process of printing an electrode. It is a schematic plan view of a printing plate. FIG. 4 is a schematic plan view in which a portion IV in FIG. 3 is enlarged. FIG. 5 is a schematic cross-sectional view taken along line VV in FIG. 4. FIG. 5 is a schematic cross-sectional view taken along line VI-VI in FIG. 4. FIG. 5 is a schematic cross-sectional view taken along line VII-VII in FIG. 4. It is a typical top view showing the structure of the electrode formed in a comparative example. It is a schematic plan view showing a part of a printing plate according to a first modification. It is a schematic plan view showing a part of a printing plate according to a second modification. It is a schematic sectional drawing showing a part of printing plate concerning the 3rd modification. It is a schematic sectional drawing showing a part of printing plate concerning the 4th modification. It is a schematic sectional drawing showing a part of printing plate concerning the 5th modification. It is a schematic sectional drawing showing a part of printing plate concerning the 6th modification. It is a schematic sectional drawing showing a part of printing plate concerning the 7th modification.

  Hereinafter, the preferable form which implemented this invention is described, taking the solar cell 1 shown in FIG. 1 as an example. However, the solar cell 1 is merely an example. The present invention is not limited to the solar cell 1 at all.

  Moreover, in each drawing referred in embodiment etc., the member which has a substantially the same function shall be referred with the same code | symbol. The drawings referred to in the embodiments and the like are schematically described, and the ratio of the dimensions of the objects drawn in the drawings may be different from the ratio of the dimensions of the actual objects. The dimensional ratio of the object may be different between the drawings. The specific dimensional ratio of the object should be determined in consideration of the following description.

(Configuration of solar cell 1)
As shown in FIG. 1, the solar cell 1 has a photoelectric conversion unit 10. The photoelectric conversion unit 10 is a member that generates carriers such as electrons and holes by receiving light. For example, the photoelectric conversion unit 10 may include a crystalline semiconductor substrate having one conductivity type. In addition, the photoelectric conversion unit 10 is arranged on one main surface of a crystalline semiconductor substrate having one conductivity type, and a first amorphous semiconductor layer having another conductivity type. And a second amorphous semiconductor layer having one conductivity type disposed on the other main surface of the crystalline semiconductor substrate. Moreover, the photoelectric conversion part 10 may have a semiconductor substrate in which the n-type dopant diffusion region and the p-type dopant diffusion region are exposed on the surface.

  The photoelectric conversion unit 10 has a light receiving surface 10a and a back surface 10b. An electrode 11 is formed on the light receiving surface 10a. Although illustration is omitted, electrodes are similarly formed on the back surface 10b. The shape of the electrode formed on the back surface 10b is not particularly limited. For example, the electrode formed on the back surface 10b may have substantially the same shape as the electrode 11 or may be formed in a planar shape.

  The material of the electrode is not particularly limited as long as it is a conductive material. The electrode can be formed of, for example, a metal such as silver, copper, aluminum, titanium, nickel, or chromium, or an alloy containing one or more of these metals. Moreover, the electrode may be comprised by the laminated body of the some conductive layer which consists of the said metal and alloy, for example.

  The electrode 11 has a plurality of finger electrode portions 12 and a plurality of bus bar portions 13a and 13b. Each of the plurality of finger electrode portions 12 extends along the y direction. The plurality of finger electrode portions 12 are arranged along the x direction perpendicular to the y direction. The bus bar portions 13 a and 13 b are electrically connected to the plurality of finger electrode portions 12. The bus bar portions 13 a and 13 b intersect with the plurality of finger electrode portions 12. Specifically, in the present embodiment, each of the bus bar portions 13a and 13b extends along the x direction.

(Manufacturing method of solar cell 1)
Next, the manufacturing method of the solar cell 1 is demonstrated.

  First, the photoelectric conversion unit 10 is prepared. Next, as illustrated in FIG. 2, the printing plate 20 is disposed on the light receiving surface 10 a of the photoelectric conversion unit 10. The conductive paste 31 is supplied onto the printing plate 20, and the conductive paste 31 is printed on the printing plate 20 by moving the squeegee 30 from the y2 side to the y1 side along the movement direction F. Thus, the electrode 11 is formed. Similarly, an electrode formed on the back surface is also formed. The solar cell 1 is completed by the above.

  Note that the conductive paste used for forming the electrode is not particularly limited as long as it includes a conductive material for forming the electrode. For example, the conductive paste may be made of a resin in which conductive particles are dispersed.

  Next, the configuration of the printing plate 20 used in the printing process of the electrode 11 will be described in detail with reference to FIGS.

  As shown in FIG. 3, the printing plate 20 has first and second openings 21, 22a, and 22b. The first opening 21 is an opening for forming the finger electrode portion 12. Therefore, a plurality of first openings 21 are formed so as to extend along the y direction. On the other hand, the second openings 22a and 22b are openings for forming the bus bar portions 13a and 13b. Therefore, the second openings 22 a and 22 b extend along the x direction and are orthogonal to the plurality of first openings 21.

  The first opening 21 includes downstream end portions 21a1, 21a2 located on the y1 side of the bus bar portions 13a, 13b, upstream end portions 21b1, 21b2 located on the y2 side of the bus bar portions 13a, 13b, and other portions. 21c. In the present embodiment, the downstream end portions 21a1, 21a2, the upstream end portions 21b1, 21b2, and the other portions 21c have different shapes. The downstream end 21a1 and the downstream end 21a2 have substantially the same shape. Therefore, here, the shape of the downstream end 21a1 is shown in FIG. 6, and FIG. 6 is used for the downstream end 21a2. The upstream end 21b1 and the upstream end 21b2 have substantially the same shape. For this reason, the shape of the upstream end 21b1 is shown in FIG. 7, and FIG. 7 is used for the upstream end 21b2.

  As shown in FIG. 5, the other part 21c is formed so that the width is constant in the z direction. That is, in the other portion 21c, the width is W1 in any portion in the z direction. The width of the other portion 21c is constant in the y direction.

  On the other hand, the downstream end portions 21 a 1 and 21 a 2 have a first portion 23 and a second portion 24. The first portion 23 is provided in a portion of the printing plate 20 on the first main surface 20a side opposite to the photoelectric conversion unit 10. The first portion 23 tapers from the first main surface 20a toward the second main surface 20b side on the photoelectric conversion unit 10 side. That is, the width of the first portion 23 decreases from the first main surface 20a toward the second main surface 20b. Specifically, in the present embodiment, the width of the first portion 23 decreases monotonically in a linear function from the first main surface 20a toward the second main surface 20b.

  The second portion 24 is located closer to the second main surface 20b than the first portion 23 is. In the present embodiment, the second portion 24 extends from the tip of the first portion 23 on the second main surface 20b side to the second main surface 20b. The width of the second portion 24 is constant in the z direction. The width of the second portion 24 is equal to the width at the tip of the first portion 23 on the second main surface 20b side. For this reason, the opening area of the second portion 24 is equal to the opening area at the tip of the first portion 23 on the second main surface 20b side. In the present embodiment, the width W2 of the first main surface 20a of the first portion 23 is equal to the width W1 of the first main surface 20a of the other portion 21c.

  The length along the z direction of the first portion 23 is preferably 0.1 to 0.6 times the thickness of the printing plate 20. The length along the z direction of the second portion 24 is preferably 0.4 to 0.9 times the thickness of the printing plate 20. The length of the second portion 24 along the z direction is preferably 0.8 to 1.0 times the length of the first portion 23 along the z direction.

  In the present embodiment, the width of the downstream end 21a1 is constant in the y direction.

  The upstream end 21b1 has a portion that tapers from the first main surface 20a side toward the second main surface 20b side. In the present embodiment, the entire upstream end 21b1 tapers from the first main surface 20a side toward the second main surface 20b side. That is, the width of the upstream end 21b1 is narrowed from the first main surface 20a toward the second main surface 20b. In the present embodiment, the width W5 of the second main surface 20b of the upstream end 21b1 is equal to the width W1 of the other portion 21c. The width W4 of the first main surface 20a of the upstream end 21b1 is wider than the width W1 of the other portion 21c. In the present embodiment, the width of the upstream end 21b1 is constant in the y direction.

  The length of the upstream end 21b1 along the y direction is shorter than the length of the downstream end 21a1 along the y direction.

  By the way, it is also conceivable to perform electrode printing using a printing plate in which the entire width of the first opening is constant in the z direction. However, in that case, the amount of paste passing through each of the upstream end and the downstream end of the first opening is different from the amount of paste passing through the other portions. Specifically, the amount of paste passing through the downstream end is greater than the amount of paste passing through other portions. Further, the amount of paste passing through the downstream end increases as it approaches the second opening. On the other hand, the passage amount of the paste at the upstream end is smaller than the passage amount of the paste at the other portions. Further, the amount of paste passing through the upstream end portion decreases as the second opening is approached. Therefore, as shown in FIG. 8, the width of the portion 112b1 located on the upstream side of the bus bar portion of the finger electrode portion 112 becomes narrower as it approaches the bus bar portion, while located on the downstream side of the bus bar portion. The width of the portion 112a1 becomes thicker as it approaches the bus bar portion. Therefore, the finger electrode portion cannot be formed with a uniform width and high accuracy.

  For example, when the printing plate described in Patent Document 1 is used, the amount of paste passing through the upstream end of the printing plate can be increased, and the amount of paste passing through the downstream end can be reduced. For this reason, the uniformity of the width | variety of the finger electrode part formed can be improved. However, when the width of the finger electrode portion is thin, it is necessary to make the width of the downstream end portion very thin. For this reason, the passing amount of the paste at the downstream end is undesirably too small, or in an extreme case, the paste may not pass. For this reason, when a printing plate described in Patent Document 1 is used in the manufacture of a solar cell having a narrow finger electrode portion, disconnection of the finger electrode portion and an increase in electrical resistance may occur.

  On the other hand, in the present embodiment, the downstream end portion 21a1 includes the first portion 23 that becomes narrower from the first main surface 20a toward the second main surface 20b side, and the second portion having a small opening area. Part 24. For this reason, the amount of paste passing through the downstream end 21a1 can be reduced by making the second portion 24 thinner. Further, the paste at the downstream end 21a1 is provided by providing the second portion 24 at a position away from the first main surface 20a and providing the first portion 23 having a large opening area on the first main surface 20a. Even when the passage amount is reduced, it is difficult for the passage amount of the paste to become undesirably too small or the downstream end 21a1 is clogged. In particular, when the width W2 of the first main surface 20a of the first portion 23 is equal to the width W1 of the other portion 21c, the amount of paste passing is undesirably reduced or the downstream end 21a1. Becomes clogged or even harder. Therefore, by using the printing plate 20 of the present embodiment, even when the finger electrode portion 12 is thin, the finger electrode portion 12 can be formed with high shape accuracy.

  In the present embodiment, the upstream end portion 21b1 has a portion that tapers from the first main surface 20a side toward the second main surface 20b side, and the upstream end portion 21b1 The width W4 of the second main surface 20b is larger than the width W1 of the other portion 21c. For this reason, the passage amount of the paste at the upstream end 21b1 is increased. Therefore, it can suppress that the upstream connection part with respect to the bus-bar parts 13a and 13b of the finger electrode part 12 becomes thin. Therefore, the finger electrode portion 12 can be formed with higher shape accuracy. In addition, the length of the upstream side connection part with respect to the bus-bar part of a finger electrode part which tends to become narrow is shorter than the length of the downstream side connection part with respect to the bus-bar part of a finger electrode part which tends to become wide. For this reason, it is preferable that the length of the upstream end 21b1 is shorter than the length of the downstream end 21a1.

  Hereinafter, modifications of the embodiment will be described. In the following description, members having substantially the same functions as those of the above embodiment are referred to by the same reference numerals, and description thereof is omitted.

  The features described in the following first to seventh modifications may be implemented singly or in combination of two or more. For example, the solar cell may satisfy both the characteristics of the first modification and the characteristics of the second modification.

(First modification)
In the above embodiment, the case where the width W2 of the first main surface 20a of the downstream end portion 21a1 is equal to the width W1 of the other portion 21c has been described. However, as shown in FIG. It may be narrowed. By doing so, it can suppress more effectively that the width | variety of the upstream connection part with respect to the bus-bar part of a finger electrode part becomes thick.

(Second modification)
In the above-described embodiment, the example in which the width is constant in the y direction at each of the upstream end portions 21b1 and 21b2 and the downstream end portions 21a1 and 21a2 has been described. However, the present invention is not limited to this configuration. For example, as shown in FIG. 10, the width W2 at the downstream end portions 21a1, 21a2 may be narrowed toward the second openings 22a, 22b. By doing so, the width | variety of the upstream connection part with respect to the bus-bar part of a finger electrode part can be made more uniform.

  Further, the width W4 at the upstream end portions 21b1 and 21b2 may be increased toward the second openings 22a and 22b. By doing so, the width | variety of the downstream connection part with respect to the bus-bar part of a finger electrode part can be made more uniform.

(Third Modification)
In the above embodiment, the example in which the length in the z direction of the second portion 24 is constant in the y direction has been described. However, the present invention is not limited to this configuration. For example, as shown in FIG. 11, the length in the z direction of the second portion 24 may be increased toward the second openings 22a and 22b. By doing so, the width | variety of the upstream connection part with respect to the bus-bar part of a finger electrode part can be made more uniform.

(Fourth modification)
In the above-described embodiment, the example in which the entire upstream end portions 21b1 and 21b2 are formed in a tapered shape toward the second main surface 20b side in the z direction has been described. However, the present invention is not limited to this configuration. For example, as shown in FIG. 12, the upstream end portions 21b1 and 21b2 also have a first portion 23 tapered toward the second main surface 20b side and a second portion 24 having a constant width. You may do it.

(Fifth modification)
In the above embodiment, an example in which the downstream end portions 21a1 and 21a2 are configured by the first and second portions 23 and 24 has been described. However, the present invention is not limited to this configuration. For example, as shown in FIG. 13, a third portion 25 that is wider toward the second main surface 20 b side than the second portion 24 may be provided on the second main surface 20 b side. .

(6th and 7th modification)
In the above-described embodiment, the example in which the width of the first portion 23 of the downstream end portions 21a1 and 21a2 is linearly narrowed toward the second main surface 20b side has been described. However, the present invention is not limited to this configuration. For example, as shown in FIGS. 14 and 15, the width of the first portion 23 of the downstream end portions 21a1 and 21a2 may be narrowed in a high-order function toward the second main surface 20b side. .

  Moreover, in the said embodiment, the bus bar parts 13a and 13b each demonstrated the example which is linear. However, in the present invention, the bus bar portion does not necessarily have to be linear. The bus bar portion may be formed in a zigzag shape, for example.

  In the above embodiment, the upstream end 21b1 is tapered toward the second main surface 20b. However, the upstream end is the same as the portion other than the upstream end and the downstream end. In addition, the width may be uniform in the z direction.

  In the above embodiment, the example in which the width W2 of the first main surface 20a of the first portion 23 is equal to the width W1 of the other portion 21c has been described, but the width W2 may be larger than the width W1. Even in such a case, since the second portion 24 is provided, it is possible to suppress an excessive amount of paste passing through the downstream end 21a1.

  In the above-described embodiment, an example in which the width of the other portion 21c is constant in the z direction has been described, but the present invention is not limited to this.

DESCRIPTION OF SYMBOLS 1 ... Solar cell 10 ... Photoelectric conversion part 10a ... Light-receiving surface 10b ... Back surface 11 ... Electrode 12 ... Finger electrode part 13a, 13b ... Bus-bar part 20 ... Printing plate 20a ... 1st main surface 20b ... 2nd main surface 21 ... 1st opening 21a1, 21a2 ... downstream end part 21b1, 21b2 ... upstream end part 22a, 22b ... 2nd opening 23 ... 1st part 24 ... 2nd part 25 ... 3rd part 30 ... Squeegee 31 ... Conductive paste

Claims (9)

A photoelectric conversion unit; and an electrode disposed on one main surface of the photoelectric conversion unit, the electrode extending in one direction, the electrode being electrically connected to the finger electrode unit, and the finger A method of manufacturing a solar cell having a bus bar portion intersecting with an electrode portion,
Placing a printing plate on one main surface of the photoelectric conversion unit;
Supplying a conductive paste on the printing plate, and forming the electrode on the printing plate by moving a squeegee from one side to the other side in the one direction;
With
The printing plate has a first opening for forming the finger electrode portion and a second opening for forming the bus bar portion and intersecting the first opening. And
The downstream end which is the second opening side end of the downstream portion located on the other side in the one direction with respect to the second opening of the first opening is the photoelectric conversion unit of the printing plate A first portion that tapers from a first main surface opposite to the second main surface side on the photoelectric conversion unit side, and is positioned closer to the photoelectric conversion unit side than the first portion And a second part having an opening area equal to the opening area at the tip of the first part on the photoelectric conversion part side.   2. The solar cell according to claim 1, wherein a width of the downstream end portion on the first main surface is equal to a width of the first main surface of a portion other than the downstream end portion of the downstream portion. Production method.   2. The solar cell according to claim 1, wherein a width of the downstream end portion on the first main surface is narrower than a width of the first main surface of a portion other than the downstream end portion of the downstream portion. Manufacturing method.   4. The method for manufacturing a solar cell according to claim 3, wherein a width of the downstream end portion on the first main surface becomes narrower toward the second opening side. 5.   5. The method for manufacturing a solar cell according to claim 1, wherein a length of the second portion in the thickness direction is longer as it goes toward the second opening.   6. The length in the thickness direction of the second portion is in a range of 0.1 to 0.6 times the length in the thickness direction of the printing plate. 6. Solar cell manufacturing method.   An upstream end which is the second opening side end of the upstream portion located on one side in the one direction from the second opening of the first opening is from the first main surface side. The first main surface of the upstream end portion has a portion that tapers toward the second main surface side, and the width of the first main surface of the upstream portion other than the upstream end portion is the first width of the upstream end portion. The manufacturing method of the solar cell as described in any one of Claims 1-6 wider than the width | variety in the main surface.   The method for manufacturing a solar cell according to claim 7, wherein a width of the upstream end portion on the first main surface becomes wider toward the second opening side.   The method for manufacturing a solar cell according to claim 7 or 8, wherein a length of the downstream portion along the one direction is longer than a length of the upstream end portion along the one direction.

Images