JP2007095941A - Photovoltaic device and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photovoltaic device which can suppress a separation of a collector from a photoelectrically converter and can suppress an increase of an output loss. <P>SOLUTION: The photovoltaic device comprises a photoelectrically converter 1, a collector 2 which is attached onto an upper face (main face) of the photoelectrically converter 1 and is composed of a copper line (metal wire) 2b, and a conductive adhering layer 3 for adhering the collector 2 to the upper face (main face) of the photoelectrically converter 1. In an area on at least the adhering layer 3 of the collector 2, an uneven shape having a recess 2a is formed. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photovoltaic device and a manufacturing method thereof, and more particularly, to a photovoltaic device in which a collector electrode made of a metal wire is attached to a main surface of a photoelectric conversion unit and a manufacturing method thereof.

  Conventionally, various photovoltaic devices are known in which a collector electrode made of a metal wire is attached to the main surface of a photoelectric conversion unit (see, for example, Patent Document 1). A conventional photovoltaic device having the same configuration as the photovoltaic device disclosed in Patent Document 1 will be described below.

  FIG. 14 is a top view showing the configuration of the above-described conventional photovoltaic device. 15 is a cross-sectional view taken along line 400-400 in FIG.

  As shown in FIGS. 14 and 15, in the photovoltaic device according to the conventional example, the collector electrode 102 made of a metal wire having a diameter of about 50 μm is formed on the upper surface of the photoelectric conversion unit 101 by the conductive adhesive layer 103. It is glued. As shown in FIG. 14, a plurality of the collector electrode 102 and the adhesive layer 103 are provided on the upper surface of the photoelectric conversion unit 101 so as to extend in parallel to each other with a predetermined interval. Further, on the upper surface of the photoelectric conversion unit 101, the two bus bar electrodes 104 extend in parallel at a predetermined interval so as to extend in a direction orthogonal to the extending direction of the collector electrode 102 and the adhesive layer 103. Is formed.

  In the photoelectric conversion unit 101, as shown in FIG. 15, a substantially intrinsic i-type amorphous material is formed on the upper surface of an n-type single crystal silicon substrate 105 having a texture structure (uneven shape) formed on the upper and lower surfaces. A porous silicon layer 106, a p-type amorphous silicon layer 107, and a transparent conductive film 108 are sequentially formed. On the upper surface of the transparent conductive film 108, the collector electrode 102 is bonded via the adhesive layer 103, and the bus bar electrode 104 (see FIG. 14) is formed. A substantially intrinsic i-type amorphous silicon layer 109, an n-type amorphous silicon layer 110, and a transparent conductive film 111 are sequentially formed on the lower surface of the n-type single crystal silicon substrate 105. Yes. Further, on the lower surface of the transparent conductive film 111, a plurality of finger electrode portions 112a formed to extend in parallel to each other with a predetermined interval, and a bus bar that collects current collected by the finger electrode portions 112a A back electrode 112 including an electrode portion (not shown) is formed.

Japanese Patent Laid-Open No. 3-6867

  However, in the photovoltaic device according to the conventional example shown in FIGS. 14 and 15, in order to increase the amount of light incident from the upper surface of the photoelectric conversion unit 101 and increase the light emission efficiency, it has an extremely large diameter of about 50 μm. Since a thin metal wire is used as the collector electrode 102, the adhesion area between the collector electrode 102 and the adhesive layer 103 is reduced. Thereby, since the adhesive strength of the collector electrode 102 to the adhesive layer 103 is reduced, there is an inconvenience that the collector electrode 102 is easily peeled off from the adhesive layer 103. As a result, there is a problem that the collector electrode 102 is easily peeled off from the photoelectric conversion unit 101. In addition, since the adhesion area between the collector electrode 102 and the adhesive layer 103 is reduced, the contact resistance between the collector electrode 102 and the adhesive layer 103 increases. Thereby, there also exists a problem that the output loss of a photovoltaic apparatus increases.

  The present invention has been made to solve the above-described problems, and one object of the present invention is to suppress the separation of the collector electrode from the photoelectric conversion unit and to increase the output loss. It is to provide a photovoltaic device capable of being suppressed.

Means for Solving the Problems and Effects of the Invention

  In order to achieve the above object, a photovoltaic device according to a first aspect of the present invention includes a photoelectric conversion unit, a collector electrode attached to the main surface of the photoelectric conversion unit, and a photoelectric conversion of the collector electrode. And an electrically conductive adhesive layer for adhering to the main surface of the portion, and at least a region of the collector electrode in contact with the adhesive layer has an uneven shape.

  In the photovoltaic device according to the first aspect, as described above, the surface area of the region in contact with the adhesive layer of the collector electrode is increased by forming an uneven shape in the region of the collector electrode in contact with the adhesive layer. Therefore, the adhesion area between the collector electrode and the adhesive layer can be increased. Thereby, since the adhesive strength with respect to the contact bonding layer of a collector electrode can be enlarged, it can suppress that a collector electrode peels from an contact bond layer. As a result, it can suppress that a collector electrode peels from a photoelectric conversion part. Further, since the adhesion area between the collector electrode and the adhesive layer can be increased, it is possible to suppress an increase in contact resistance between the collector electrode and the conductive adhesive layer. Thereby, it can suppress that the output loss of a photovoltaic apparatus increases.

  In the photovoltaic device according to the first aspect, preferably, the concave and convex shape of the collector electrode is provided with a plurality of concave portions. If comprised in this way, since the surface area of the area | region which contact | connects the adhesion layer of a collector electrode can be enlarged, the adhesion area of a collector electrode and an adhesion layer can be enlarged more. Thereby, since the adhesive strength with respect to the contact bonding layer of a collector electrode can be enlarged, it can suppress more that a collector electrode peels from an adhesive layer. As a result, it can suppress more that a collector electrode peels from a photoelectric conversion part.

  In the photovoltaic device according to the first aspect, preferably, the adhesive layer contains metal particles, and the concave and convex portions of the collector electrode are filled with the metal particles of the adhesive layer. If comprised in this way, since the contact area of a collector electrode and the metal particle of an contact bonding layer can be enlarged, it can suppress more that the contact resistance between a collector electrode and a contact bonding layer becomes large. Thereby, it can suppress more that the output loss of a photovoltaic apparatus increases.

  In the photovoltaic device in which the adhesive layer contains metal particles, the opening width of the concave and convex portions of the collector electrode is preferably larger than the particle diameter of the metal particles in the adhesive layer. With this configuration, the concave and convex portions of the collector electrode can be easily filled with the metal particles of the adhesive layer, so that the contact area between the collector electrode and the metal particles of the adhesive layer can be easily increased. can do.

  In the photovoltaic device according to the first aspect, preferably, the collector electrode has a substantially circular cross-sectional shape, and an uneven shape is formed on the entire circumferential surface of the collector electrode. With this configuration, even when a collector electrode having a substantially circular cross-sectional shape is attached to the main surface of the photoelectric conversion unit in a twisted state, unevenness is easily formed in the region in contact with the adhesive layer of the collector electrode. Since the shape can be arranged, the adhesion area between the collector electrode and the adhesive layer can be easily increased.

  In the photovoltaic device according to the first aspect, preferably, a plurality of concave and convex concave portions of the collector electrode are provided at predetermined intervals along an outer periphery of a cross section that intersects with a direction in which the collector electrode extends. A plurality of electrodes are provided at predetermined intervals along the direction in which the electrodes extend. If comprised in this way, since the surface area of the area | region which contact | connects the adhesion layer of a collector electrode can be enlarged, the adhesion area of a collector electrode and an adhesion layer can be enlarged more.

  According to a second aspect of the present invention, there is provided a method for manufacturing a photovoltaic device comprising: a step of forming a concavo-convex shape by a sandblast method in a predetermined region of a metal wire; and a region in which the concavo-convex shape of the metal wire is formed. And a step of forming a collecting electrode by adhering to the main surface of the photoelectric conversion portion with the adhesive layer.

  In the method for producing a photovoltaic device according to the second aspect, as described above, the region where the metal wire irregularities are formed is adhered to the main surface of the photoelectric conversion layer by the adhesive layer, whereby the collector electrode is formed. By providing the forming step, the surface area of the region in contact with the adhesive layer of the collector electrode can be increased, so that the adhesive area between the collector electrode and the adhesive layer can be increased. Thereby, since the adhesive strength with respect to the contact bonding layer of a collector electrode can be enlarged, it can suppress that a collector electrode peels from an contact bond layer. As a result, it can suppress that a collector electrode peels from a photoelectric conversion part. Further, since the adhesion area between the collector electrode and the adhesive layer can be increased, it is possible to suppress an increase in contact resistance between the collector electrode and the conductive adhesive layer. Thereby, it can suppress that the output loss of a photovoltaic apparatus increases. In addition, by providing a step of forming a concavo-convex shape by a sandblast method in a predetermined region of the metal wire, the concavo-convex shape can be easily formed on the metal wire.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a top view showing a configuration of a photovoltaic device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line 100-100 in FIG. FIG. 3 is an enlarged cross-sectional view of the vicinity of the adhesive layer of the photovoltaic device according to the embodiment shown in FIG. 4 is a cross-sectional view taken along line 200-200 in FIG. FIG. 5 is a cross-sectional view taken along line 300-300 in FIG. First, with reference to FIGS. 1-5, the structure of the photovoltaic apparatus by one Embodiment of this invention is demonstrated.

  In the photovoltaic device according to one embodiment of the present invention, as shown in FIG. 1, a collector electrode 2 made of a copper wire (metal wire) is formed on an upper surface (main surface) of the photoelectric conversion unit 1 with an epoxy-based heat. It is adhered by a conductive adhesive layer 3 made of a curable conductive paste (silver (Ag) paste). The collector electrode 2 and the adhesive layer 3 are arranged on the upper surface of the photoelectric conversion unit 1 at a pitch (inter-center distance) of about 2 mm in the A direction of FIG. 1 and extend in parallel to the B direction of FIG. A plurality are provided.

  Here, in the present embodiment, the collector electrode 2 is formed to have a substantially circular cross-sectional shape having a diameter of about 50 μm. Moreover, in the area | region which contact | connects the contact bonding layer 3 of the collector electrode 2, as shown in FIG.2 and FIG.4, the uneven | corrugated shape which has several recessed part 2a is formed. A plurality of the concave and convex concave portions 2a are provided at predetermined intervals along the outer periphery of the cross section intersecting with the extending direction of the collecting electrode 2, and along the extending direction of the collecting electrode 2 (the B direction in FIG. 4). Are also provided at predetermined intervals. Further, as shown in FIG. 3, the depth of the recess 2a is the recess depth (H), the distance between the valleys (bottoms) of the adjacent recesses 2a is the recess pitch (P), and the opening width of the recess 2a is the recess Assuming the opening width (W), the recess 2a of the collector electrode 2 has a recess depth (H) of about 2 μm to about 15 μm, a recess pitch (P) of about 2 μm to about 15 μm, and about 1.8 μm to about 13 μm. The recess opening width (W) is formed. And this recessed part 2a has the granular filler 3a which consists of silver (Ag) which has the average diameter (particle diameter) of about 1.1 micrometer contained in the contact bonding layer 3, and has the maximum length (particle diameter) of about 6 micrometers. A flaky filler 3b made of silver (Ag) is filled. The granular filler 3a and the flaky filler 3b are examples of the “metal particles” in the present invention.

  Moreover, as shown in FIG. 1, it extends in a direction (A direction) orthogonal to the direction in which the collector electrode 2 extends, at a position about 25 mm inside from both ends of the adhesive layer 3 on the photoelectric conversion unit 1. Two bus bar electrodes 4 are formed. The bus bar electrode 4 is made of an epoxy-based thermosetting conductive paste (silver (Ag) paste) and has a width of about 1.5 mm. Further, in the region where the collector electrode 2 and the adhesive layer 3 intersect with the bus bar electrode 4, the bus bar electrode 4 is formed so as to cover the collector electrode 2 and the adhesive layer 3 as shown in FIG. A plurality of collector electrodes 2 are electrically connected to each other by the bus bar electrode 4.

In addition, as shown in FIG. 2, the photoelectric conversion unit 1 has a resistivity of about 1 Ω · cm, a size of about 104 mm (vertical) × about 104 mm (horizontal), and a thickness of about 300 μm, and (100 The texture structure (uneven shape) is formed on the upper surface and the lower surface of the n-type single crystal silicon substrate 5 having a surface. A substantially intrinsic i-type amorphous silicon layer 6 having a thickness of about 5 nm is formed on the upper surface of the n-type single crystal silicon substrate 5. A p-type amorphous silicon layer 7 having a thickness of about 5 nm and a transparent conductive film 8 having a thickness of about 80 nm to about 100 nm are sequentially formed on the upper surface of the i-type amorphous silicon layer 6. ing. The transparent conductive film 8 is constituted by about 5 wt% ITO consisting InO ₂ containing SnO ₂ of (Indium Tin Oxide) film.

  Further, on the lower surface of the n-type single crystal silicon substrate 5, a substantially intrinsic i-type amorphous silicon layer 9 having a thickness of about 5 nm and an n-type amorphous silicon layer 10 having a thickness of about 5 nm are formed. The transparent conductive film 11 having a thickness of about 80 nm to about 100 nm is sequentially formed. Also, on the lower surface of the transparent conductive film 11, a plurality of finger electrode portions 12a formed so as to extend in parallel with each other at a predetermined interval, and a bus bar that collects current collected by the finger electrode portions 12a A back electrode 12 including an electrode portion (not shown) is formed. The back electrode 12 is formed of an epoxy thermosetting conductive paste (silver (Ag) paste).

  6-8 is a figure for demonstrating the attachment process of the copper wire to the photoelectric conversion part of the photovoltaic apparatus by this embodiment. Next, with reference to FIGS. 1-8, the manufacturing process of the photovoltaic apparatus by one Embodiment of this invention is demonstrated.

  First, the manufacturing process of the photoelectric conversion unit 1 will be described with reference to FIGS.

2 and 4, n having a resistivity of about 1 Ω · cm, a size of about 104 mm (vertical) × about 104 mm (horizontal), a thickness of about 300 μm, and a (100) plane The textured structure (uneven shape) is formed on the upper and lower surfaces of the n-type single crystal silicon substrate 5 by etching the single crystal silicon substrate 5 with an alkaline aqueous solution. Thereafter, impurities are removed by washing. And using RF plasma CVD method, frequency: about 13.56 MHz, formation temperature: about 100 ° C. to about 300 ° C., reaction pressure: about 5 Pa to about 100 Pa, RF power: about 1 mW / cm ² to about 500 mW / cm Under the condition ² , an i-type amorphous silicon layer 6 having a thickness of about 5 nm and a p-type amorphous silicon layer 7 having a thickness of about 5 nm are formed on the upper surface of the n-type single crystal silicon substrate 5. Sequentially formed. Note that p-type dopants for forming the p-type amorphous silicon layer 7 include group III elements B, Al, Ga, and In. When the p-type amorphous silicon layer 7 is formed, a compound gas containing at least one of the above-described p-type dopants is mixed with a source gas such as SiH ₄ (silane) gas to thereby form a p-type amorphous silicon layer. 7 can be formed.

  Next, an i-type amorphous having a thickness of about 5 nm is formed on the lower surface of the n-type single crystal silicon substrate 5 by the same formation process as the i-type amorphous silicon layer 6 and the p-type amorphous silicon layer 7. A silicon layer 9 and an n-type amorphous silicon layer 10 having a thickness of about 5 nm are sequentially formed. The n-type dopant used when forming the n-type amorphous silicon layer 10 includes P, N, As, and Sb, which are group 5 elements. When the n-type amorphous silicon layer 10 is formed, the n-type amorphous silicon layer 10 can be formed by mixing a compound gas containing at least one of the above-described n-type dopants into the source gas. .

Next, transparent conductive films 8 and 11 made of an ITO film are formed on the upper surface of the p-type amorphous silicon layer 7 and the lower surface of the n-type amorphous silicon layer 10 by sputtering, respectively. . Specifically, when the transparent conductive films 8 and 11 are formed, a target made of a sintered body of In ₂ O ₃ powder containing about 5% by mass of SnO ₂ powder is used as a chamber (see FIG. It installs in the cathode (not shown) in a not shown. In this case, it is possible to change the amount of Sn in the ITO film by changing the amount of SnO ₂ powder. The amount of Sn with respect to In is preferably about 1% by mass to about 10% by mass.

Then, the n-type single crystal silicon substrate 5 on which the p-type amorphous silicon layer 7 and the n-type amorphous silicon layer 10 are formed is disposed in parallel with the cathode. Then, after evacuating the chamber (not shown), the substrate is heated using a heater (not shown) until the substrate temperature reaches about 200 ° C. Then, in a state where the substrate temperature is about 200 ° C., a mixed gas of Ar gas and O ₂ gas is flowed to maintain the pressure at about 0.4 Pa to about 1.3 Pa, and at the cathode, about 0.5 kW to about Discharging is started by applying DC power of 2 kW. In this manner, the transparent conductive films 8 and 11 are formed on the upper surface of the p-type amorphous silicon layer 7 and the lower surface of the n-type amorphous silicon layer 10, respectively, to a thickness of about 80 nm to about 100 nm. To do.

  Next, with reference to FIG. 3 and FIGS. 6-8, the attachment process of the copper wire to the photoelectric conversion part 1 is demonstrated.

First, after forming a concavo-convex shape by a sandblast method in a predetermined region of a copper wire 2b having a diameter of about 50 μm (see FIG. 6), the copper wire 2b having the concavo-convex shape formed thereon is formed into a bobbin 21 (see FIG. 6) Take up around. Specifically, alumina particles having an average particle size of about 1.8 μm to about 13 μm are sprayed at a spray pressure of about 49 × 10 ⁴ N / m ² to about 29.4 × 10 ⁴ N / m ² by sandblasting. It is made to collide with the copper wire 2b (refer FIG. 6). Accordingly, the copper wire 2b has an average recess depth (H) (see FIG. 3) of about 2 μm to about 15 μm, an average recess pitch (P) of about 2 μm to about 15 μm, and an average of about 1.8 μm to about 13 μm. A concave-convex shape having a concave opening width (W) is formed. The copper wire 2b is an example of the “metal wire” in the present invention. The concave / convex shape is formed so that the concave portion depth (H) and the concave portion pitch (P) have a size of about 16 μm or more, which is about 30% or more of the diameter (about 50 μm) of the copper wire 2b. In this case, since the strength of the copper wire 2b itself is reduced, the copper wire 2b is easily broken in the step of attaching the copper wire 2b to the photoelectric conversion unit 1 described later. For this reason, the recess depth (H) and the recess pitch (P) are preferably formed to a size of less than about 16 μm.

  Next, as shown in FIG. 6, the winding member 22 having four cylindrical portions 22a arranged in parallel is rotated at a constant speed so that the copper wire 2b drawn from the bobbin 21 does not break or bend. At the same time, while applying a predetermined tension (about 0.196 N) to the copper wire 2b, the copper wire 2b is wound around the cylindrical portion 22a of the winding member 22 so as to be arranged in parallel at a pitch of about 2 mm. At this time, the copper wire 2b is wound so that the uneven shape is directed outward with respect to the rotation center O1 of the winding member 22.

  Then, as shown in FIG. 7, an epoxy-based thermosetting conductive paste (silver (Ag) paste) 3c having a thickness of about 50 μm is applied to the region where the concavo-convex shape of the copper wire 2b is formed. Specifically, the thickness adjusting roller 24 is arranged at a predetermined distance from the cylindrical roller 23, and the roller 23 is rotated to apply the conductive paste 3c having a thickness of about 50 μm to the surface of the roller 23. To do. Thereafter, while applying a predetermined tension (about 0.196 N) to the copper wire 2b, the conductive paste 3c is rotated by rotating the roller 23 in a state where the conductive paste 3c of the roller 23 is in contact with the copper wire 2b. Is transferred to the copper wire 2b. At this time, the roller 23 is translated at the same size as the transfer speed of the conductive paste 3a. In this case, the contact area between the copper wire 2b and the conductive paste 3c can be reduced. As a result, the stress applied to the copper wire 2b when the conductive paste 3c is pulled away from the copper wire 2b can be reduced, so that the copper wire 2b can be prevented from being broken or bent. In the present embodiment, the conductive paste 3c has a granular filler 3a made of silver (Ag) having an average diameter (particle diameter) of about 1.1 μm and a maximum length (particle diameter) of about 6 μm. And flaky filler 3b made of silver (Ag).

  Thereafter, as shown in FIG. 8, the photoelectric conversion unit 1 is fixed to the fixed base 25. Then, the copper wires 2b, which are arranged in parallel at a pitch of about 2 mm and coated with the conductive paste 3c, are arranged in a predetermined region of the photoelectric conversion unit 1. Then, with the thermosetting conductive paste 3c in contact with the upper surface of the photoelectric conversion unit 1, a heat treatment is performed at a temperature of about 200 ° C. for about 30 minutes by a lamp heater (not shown), thereby forming the conductive paste. The adhesive layer 3 is formed by curing 3c. Thereby, the collector electrode 2 made of the copper wire 2 b is formed on the upper surface of the photoelectric conversion unit 1. That is, in the present embodiment, the copper wire 2b drawn from one bobbin 21 is wound in parallel with the cylindrical portion 22a of the winding member 22 and bonded to the photoelectric conversion portion 1, thereby forming the collecting electrode 2. The number of bobbins 21 can be reduced as compared with the conventional method in which copper wires 2b drawn from the same number of bobbins 21 as the collecting electrodes 2 are arranged in parallel and bonded to the photoelectric conversion unit 1. Thereby, it is possible to save the space for arranging the bobbin 21. In the present embodiment, as shown in FIG. 3, the collector electrode 2 is formed in a state where the granular filler 3 a and the flaky filler 3 b included in the adhesive layer 3 are filled in the recess 2 a.

  Next, a manufacturing process of the bus bar electrode 4 and the back electrode 12 will be described with reference to FIGS.

  First, as shown in FIG. 1, the screen printing method is used, and at a position approximately 25 mm inside from both ends of the adhesive layer 3 on the photoelectric conversion unit 1, orthogonal to the extending direction of the collector electrode 2 and the adhesive layer 3. The conductive paste is transferred so as to extend in the direction of the movement. As this conductive paste, an epoxy-based thermosetting conductive paste (silver (Ag) paste) is used. Thereafter, the conductive paste is cured by heating at about 200 ° C. for about 1 hour in a heating furnace. Thereby, a bus bar electrode 4 for connecting the plurality of collector electrodes 2 to each other is formed in a predetermined region of the adhesive layer 3 on the photoelectric conversion unit 1. At this time, at a position where the bus bar electrode 4 intersects the collector electrode 2 and the adhesive layer 3, the bus bar electrode 4 is formed so as to cover the collector electrode 2 and the adhesive layer 3, as shown in FIG.

  Thereafter, using a screen printing method, an epoxy thermosetting conductive paste (silver (Ag) paste) is transferred onto a predetermined region of the transparent conductive film 11 on the back surface side, and then is transferred to about 200 in a heating furnace. The back surface electrode 12 is formed by curing the conductive paste by heating at a temperature of about 1 hour. As a result, a plurality of finger electrode portions 12a formed on the lower surface of the transparent conductive film 11 so as to extend in parallel with each other at a predetermined interval, and a bus bar electrode portion that collects the current collected by the finger electrode portions 12a ( A back electrode 12 made of (not shown) is formed. In this way, the photovoltaic device according to the embodiment of the present invention shown in FIG. 1 is manufactured.

  In the present embodiment, as described above, the surface area of the region in contact with the adhesive layer 3 of the collector electrode 2 can be increased by forming an uneven shape in the region of the collector electrode 2 in contact with the adhesive layer 3. The adhesion area between the collector electrode 2 and the adhesive layer 3 can be increased. Thereby, since the adhesive strength with respect to the adhesive layer 3 of the collector electrode 2 can be enlarged, it can suppress that the collector electrode 2 peels from the adhesive layer 3. FIG. As a result, it is possible to suppress the collector electrode 2 from peeling from the photoelectric conversion unit 1. Moreover, since the adhesion area of the collector electrode 2 and the contact bonding layer 3 can be enlarged, it can suppress that the contact resistance between the collector electrode 2 and the electroconductive contact bonding layer 3 becomes large. Thereby, it can suppress that the output loss of a photovoltaic apparatus increases.

  Moreover, in this embodiment, since the surface area of the area | region which contact | connects the contact bonding layer 3 of the collector electrode 2 can be enlarged by providing several uneven | corrugated 2a in the uneven | corrugated shape of the collector electrode 2, it adheres to the collector electrode 2 The adhesion area with the layer 3 can be further increased. Thereby, since the adhesive strength with respect to the contact bonding layer 3 of the collector electrode 2 can be enlarged more, it can suppress more that the collector electrode 2 peels from the contact bonding layer 3. FIG. As a result, the collector electrode 2 can be further prevented from peeling from the photoelectric conversion unit 1.

  Moreover, in this embodiment, the collector electrode 2 and the adhesive layer 3 are filled by filling the concave and convex concave portion 2 a of the collector electrode 2 with the granular filler 3 a and the flaky filler 3 b made of silver (Ag) of the adhesive layer 3. Since the contact area between the granular filler 3a and the flaky filler 3b can be increased, the contact resistance between the collector electrode 2 and the adhesive layer 3 can be further suppressed. Thereby, it can suppress more that the output loss of a photovoltaic apparatus increases.

  In the present embodiment, the collector opening 2 is formed such that the recess opening width (W) of the concave-convex recess 2 a is larger than the particle diameters of the granular filler 3 a and the flaky filler 3 b of the adhesive layer 3. 2 can be easily filled with the granular filler 3a and flaky filler 3b of the adhesive layer 3, so that the collector electrode 2 and the granular filler 3a and flaky filler 3b of the adhesive layer 3 The contact area can be easily increased.

  Further, in the present embodiment, a plurality of concave and convex concave portions 2 a of the collector electrode 2 are provided at predetermined intervals along the outer periphery of the cross section intersecting with the direction in which the collector electrode 2 extends, and along the direction in which the collector electrode 2 extends. In addition, by providing a plurality at predetermined intervals, the surface area of the region in contact with the adhesive layer 3 of the collector electrode 2 can be increased, so that the adhesive area between the collector electrode 2 and the adhesive layer 3 can be increased.

  Moreover, in this embodiment, an uneven | corrugated shape can be easily formed in the copper wire 2b by forming an uneven | corrugated shape in the predetermined area | region of the copper wire 2b by the sandblasting method.

  FIG. 9 is a diagram for explaining an experiment conducted for confirming the effect according to the embodiment of the present invention. Next, an experiment conducted to confirm the effect of the above-described embodiment of the present invention will be described. In this experiment, the size of the concavo-convex shape of the copper wire 2b was changed, and the photovoltaic devices according to Examples 1-1 to 1-5 and Comparative Example 1-1 were manufactured. The peel strength of the collecting electrode 2 and the output of the electromotive force device were measured.

(Example 1-1)
In Example 1-1, by using a sandblasting method, alumina particles having an average particle diameter of about 1.8 μm were made to collide with the copper wire 2b with an injection pressure of about 49 × 10 ⁴ N / m ² , thereby producing a copper Concave and convex shapes having an average concave depth (H) of about 2 μm, an average concave pitch (P) of about 2 μm, and an average concave opening width (W) of about 1.8 μm were formed on the line 2b. Except for this, a photovoltaic device according to Example 1-1 was fabricated in the same manner as in the above embodiment.

(Example 1-2)
In Example 1-2, by using the sandblasting method, alumina particles having an average particle diameter of about 4 μm were made to collide with the copper wire 2b at an injection pressure of about 39.2 × 10 ⁴ N / m ² , thereby producing a copper Concave and convex shapes having an average recess depth (H) of about 5 μm, an average recess pitch (P) of about 5 μm and an average aperture width (W) of about 4 μm were formed on the line 2b. Except for this, a photovoltaic device according to Example 1-2 was fabricated in the same manner as in the above embodiment.

(Example 1-3)
In Example 1-3, by using the sandblasting method, alumina particles having an average particle diameter of about 6 μm are made to collide with the copper wire 2b with an injection pressure of about 35.3 × 10 ⁴ N / m ² , thereby producing a copper Concave and convex shapes having an average recess depth (H) of about 8 μm, an average recess pitch (P) of about 8 μm and an average aperture width (W) of about 6 μm were formed on the line 2b. Except for this, a photovoltaic device according to Example 1-3 was fabricated in the same manner as in the above embodiment.

(Example 1-4)
In Example 1-4, by using a sandblasting method, alumina particles having an average particle diameter of about 10 μm are made to collide with the copper wire 2b at an injection pressure of about 31.4 × 10 ⁴ N / m ² , thereby producing copper. Concave and convex shapes having an average concave depth (H) of about 12 μm, an average concave pitch (P) of about 12 μm, and an average concave opening width (W) of about 10 μm were formed on the line 2b. Except for this, a photovoltaic device according to Example 1-4 was fabricated in the same manner as in the above embodiment.

(Example 1-5)
In Example 1-5, by using a sandblasting method, alumina particles having an average particle diameter of about 13 μm are made to collide with the copper wire 2b at an injection pressure of about 29.4 × 10 ⁴ N / m ² , thereby producing a copper Concave and convex shapes having an average recess depth (H) of approximately 15 μm, an average recess pitch (P) of approximately 15 μm, and an aperture width (W) of approximately 13 μm on the average were formed on the line 2b. Except for this, a photovoltaic device according to Example 1-5 was fabricated in the same manner as in the above embodiment.

(Comparative Example 1-1)
In Comparative Example 1-1, a copper wire having no uneven shape was used as a collector electrode. Except for this, a photovoltaic device according to Comparative Example 1-1 was produced in the same manner as in the above embodiment.

  Next, the peel strength of the collector electrode 2 was measured for the photovoltaic devices according to Examples 1-1 to 1-5 and Comparative Example 1-1 manufactured as described above. Specifically, as shown in FIG. 9, the photoelectric conversion unit 1 was fixed, one end of the collector electrode 2 was peeled off, and the photoelectric conversion unit 1 was bent in a direction perpendicular to the upper surface of the photoelectric conversion unit 1. Then, the one end of the bent collector electrode 2 is sandwiched between the clips 26a of the measuring device 26, and the collector electrode 2 is pulled upward to measure the peak intensity when the collector electrode 2 peels from the photoelectric conversion unit 1. 26.

Moreover, the output was measured with the solar simulator about the photovoltaic apparatus by Example 1-1-Example 1-5 and Comparative Example 1-1 which were produced as mentioned above. The air permeation amount (Air Mass) was 1.5, the irradiance was 100 mW / cm ² , and the temperature was 25 ° C.

  Table 1 below shows the measurement results of the peel strength of the collector electrode 2 and the output of the photovoltaic device. Table 1 shows the normalized peel strength normalized by the peel strength according to Comparative Example 1-1 and the normalized output normalized by the output of the photovoltaic device according to Comparative Example 1-1. .

上記表１の結果から、実施例１−１〜１−５の規格化剥離強度（実施例１−１：１．０８、実施例１−２：１．１、実施例１−３：１．０８、実施例１−４：１．０８、実施例１−５：１．０６）は、凹凸形状を有しない銅線を集電極として用いた従来構造による比較例１−１の規格化剥離強度（比較例１−１：１）に比べて大きいことがわかる。すなわち、実施例１−１〜１−５では、比較例１−１に比べて、集電極２の剥離を抑制することができることがわかった。これは、凹凸形状が形成されていない従来構造による比較例１−１の集電極と異なり、凹凸形状が形成されている実施例１−１〜１−５による集電極２では、集電極２と接着層３との接触面積が大きいことにより、集電極２と接着層３との接着強度が大きくなったことによると考えられる。これにより、集電極２が光電変換部１から剥離するのを抑制するためには、集電極２に凹凸形状を形成することが好ましいことが判明した。

From the results of Table 1 above, the normalized peel strengths of Examples 1-1 to 1-5 (Example 1-1: 1.08, Example 1-2: 1.1, Example 1-3: 1. 08, Examples 1-4: 1.08, and Examples 1-5: 1.06) are normalized peel strengths of Comparative Example 1-1 with a conventional structure using a copper wire having no uneven shape as a collecting electrode. It can be seen that it is larger than (Comparative Example 1-1: 1). That is, in Examples 1-1 to 1-5, it was found that peeling of the collector electrode 2 can be suppressed as compared with Comparative Example 1-1. This is different from the collector electrode of Comparative Example 1-1 having a conventional structure in which the concavo-convex shape is not formed, and in the collector electrode 2 according to Examples 1-1 to 1-5 in which the concavo-convex shape is formed, This is considered to be due to the fact that the adhesive strength between the collector electrode 2 and the adhesive layer 3 is increased due to the large contact area with the adhesive layer 3. Thereby, in order to suppress that the collector electrode 2 peels from the photoelectric conversion part 1, it turned out that forming uneven | corrugated shape in the collector electrode 2 is preferable.

  Further, from the results of Table 1 above, the normalized outputs of Examples 1-2 to 1-5 (Example 1-2: 1.002, Example 1-3: 1.008, Example 1-4: 1) .009, Example 1-5: 1.007) is a normalized output (Comparative Example 1-1: 1) of Comparative Example 1-1 by a conventional structure using a copper wire having no uneven shape as a collector electrode. It can be seen that it is large. That is, in Examples 1-2 to 1-5, it was found that the output of the photovoltaic device can be improved as compared with Comparative Example 1-1. This is different from the collector electrode of Comparative Example 1-1 having a conventional structure in which the concavo-convex shape is not formed, and in the collector electrode 2 according to Examples 1-2 to 1-5 in which the concavo-convex shape is formed, Since the contact area with the adhesive layer 3 is large, the contact area between the collector electrode 2 and the granular filler 3a and flaky filler 3b of the adhesive layer 3 is increased, and the collector electrode 2, the granular filler 3a of the adhesive layer 3 and It is considered that the contact resistance with the flaky filler 3b was reduced. The output of the photovoltaic device according to Example 1-1 was not improved as compared with the output of the photovoltaic device according to Comparative Example 1-1. (W) was not formed sufficiently larger than the particle diameter of the flaky filler 3b of the adhesive layer 3, so that the flaky filler 3b of the adhesive layer 3 was sufficiently placed in the concave and convex portion 2a of the uneven electrode 2 This is considered to be because it could not be filled.

  Further, the output of the photovoltaic device according to Examples 1-3 to 1-5 was particularly improved because the concave opening width (W) of the concave-convex concave portion 2a of the collector electrode 2 was the granular filler 3a of the adhesive layer 3 In addition, the concave and convex portions 2a of the collector electrode 2 can be sufficiently filled with the granular filler 3a and the flaky filler 3b of the adhesive layer 3 by being formed sufficiently larger than the particle size of the flaky filler 3b. It is thought that it was because it was made.

  The embodiments and examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments and examples but by the scope of claims for patent, and includes all modifications within the meaning and scope equivalent to the scope of claims for patent.

  For example, in the above embodiment, a photovoltaic device in which a p-type amorphous silicon layer is formed on an n-type single crystal silicon substrate via an i-type amorphous silicon layer has been described as an example. Any photovoltaic device having a structure using a collector electrode made of a metal wire, such as a single crystal silicon system, a polycrystalline silicon system, a thin film silicon system, a compound semiconductor system, a dye sensitizing system, an organic system, etc. The present invention can be applied to various photovoltaic devices.

  In the above embodiment, an epoxy-based thermosetting conductive paste is used as the material for the adhesive layer, bus bar electrode, and back electrode. However, the present invention is not limited to this, and the adhesive layer, bus bar electrode, and back electrode are used. As the material, a conductive paste containing a resin material other than an epoxy resin may be used. For example, a conductive paste containing a resin material such as polyester, acrylic, polyvinyl, polyurethane, and phenol may be used. However, in this case, it is necessary to cure the conductive paste by using curing conditions suitable for each resin.

  In the above-described embodiment, the example in which the concavo-convex shape is formed only in the region in contact with the adhesive layer of the collector electrode is described. However, the present invention is not limited to this, and the first modification example of the present embodiment shown in FIG. As described above, an uneven shape may be formed on the entire circumferential surface of the collector electrode 31 having a substantially circular cross-sectional shape. In this case, even when the collector electrode 31 having a circular cross-sectional shape is attached on the upper surface of the photoelectric conversion unit 1 in a twisted state, the uneven shape is easily arranged in the region of the collector electrode 31 that is in contact with the adhesive layer 3. Therefore, the adhesion area between the collecting electrode 31 and the adhesive layer 3 can be easily increased.

  In the above embodiment, the copper wire drawn out from the bobbin has been shown to be wound on the photoelectric conversion unit in parallel with the four cylindrical portions of the winding member. However, the present invention is not limited to this, and the winding is not limited thereto. In addition to providing two or more cylindrical portions of the take-up member, the copper wire drawn out from the bobbin may be wound in parallel to the two or more cylindrical portions of the take-up member and bonded to the photoelectric conversion portion, One column portion having a rectangular cylindrical shape or a rectangular column shape may be provided, and the copper wire drawn out from the bobbin may be wound in parallel with the one column portion of the winding member and bonded to the photoelectric conversion unit.

  Moreover, although this embodiment demonstrated the example which formed the uneven | corrugated shape of the copper wire by the sandblast method, this invention is not restricted to this, By pressing the type | mold with which the uneven | corrugated shape was formed on a copper wire, An uneven shape may be formed, or the uneven shape may be formed on the copper wire by irradiating the surface of the copper wire with a laser.

  Moreover, although the said embodiment demonstrated the example which formed the collector electrode so that it had a substantially circular cross-sectional shape, this invention is not limited to this, The 2nd modification of this embodiment shown in FIG. As described above, the collector electrode 32 may have a rectangular cross-sectional shape, and a concave / convex shape having a concave portion 32 a may be formed on the surface of the collector electrode 32 bonded to the adhesive layer 3. In this case, the contact area between the collector electrode 32 and the adhesive layer 3 can be increased.

  Moreover, in the said embodiment, although the example which used silver as a metal particle of an electrically conductive paste was shown, this invention is not limited to this as long as it has electroconductivity not only this but electroconductivity. As the metal particles of the paste, for example, a metal such as gold, copper, nickel, or aluminum may be used, or an alloy thereof may be used. It is also possible to use a mixture of two or more metals.

  In the above embodiment, an example in which a granular filler having an average diameter of about 1.1 μm and a flaky filler having a maximum length of about 6 μm is used as the metal particles of the conductive paste is described. However, the present invention is not limited to this, and as the metal particles of the conductive paste, fillers having various shapes and sizes may be used in combination, or as in the third modification of the present embodiment shown in FIG. Only a filler may be used or only a flaky filler may be used.

  In the above embodiment, the texture structure is formed on the upper and lower surfaces of the n-type single crystal silicon substrate. However, the present invention is not limited to this, and the texture structure is formed on the upper and lower surfaces of the n-type single crystal silicon substrate. (Uneven shape) may not be formed.

  Moreover, although the said embodiment demonstrated the example which produced the photovoltaic device using one photoelectric conversion part, this invention is not limited to this, A photovoltaic device is used using two or more photoelectric conversion parts. May be produced. In this case, as in the fourth modification of the present embodiment shown in FIG. 13, the collector electrode 33 made of a copper wire (metal wire) formed with an uneven shape (not shown) is connected to the adjacent photoelectric conversion unit 1. It may be used as a back electrode. A bus bar electrode (not shown) may be provided to connect the plurality of collector electrodes 33 to each other.

  Moreover, in the said embodiment, although the copper wire of the circular cross section which has a diameter of about 50 micrometers was used as a collector electrode, this invention is not restricted to this, The metal wire of various structures can be used as a collector electrode. For example, a metal wire having a diameter other than about 50 μm, a metal wire made of a metal or an alloy other than a copper wire, or a metal wire obtained by plating a metal or alloy on a part or all of the surface is used as a collecting electrode. be able to. Various configurations can also be applied to the number and interval of collecting electrodes.

  In the above embodiment, the two bus bar electrodes having a width of about 1.5 mm are formed so as to extend in parallel to each other at positions of about 25 mm from the end portions on both sides of the photoelectric conversion unit. However, the present invention is not limited to this, and various configurations other than the above can be applied to the number, width, and formation position of the bus bar electrodes.

  In the above embodiment, the bus bar electrode covers the collector electrode in the region where the bus bar electrode and the collector electrode intersect. However, the present invention is not limited to this, and the bus bar electrode and the collector electrode are electrically connected. The bus bar electrode does not need to be formed so as to cover the entire area on the upper surface of the collector electrode in the region where the bus bar electrode and the collector electrode intersect, but a part of the upper surface of the collector electrode A bus bar electrode may be provided so as to cover only.

  Moreover, in the said embodiment, although the back surface electrode was formed after forming the contact bonding layer of the surface side of a photoelectric conversion part, this invention is not restricted to this, Before forming an contact bonding layer after forming a transparent conductive film A back electrode may be formed. Further, the back electrode may be formed after bringing the collector electrode into contact with the adhesive layer.

  Moreover, in the said embodiment, although a back surface electrode is formed by heating and hardening an electrically conductive paste (silver (Ag) paste), this invention is not limited to this, A back surface electrode is formed by methods other than the above. It may be formed. For example, the back electrode may be formed by evaporating Al or the like, or the back electrode may be formed by adhering a metal wire with an adhesive layer in the same manner as the collector electrode on the front surface side.

  Moreover, in the said embodiment, although the back surface electrode which consists of a bus-bar electrode part and a finger electrode part was formed on the lower surface of the transparent conductive film of a back surface side, this invention is not limited to this, The lower surface of the transparent conductive film of a back surface side A back electrode may be formed so as to cover the entire top.

  Moreover, in the said embodiment, although silicon (Si) was used as a semiconductor material, this invention is not restricted to this, SiGe, SiGeC, SiC, SiN, SiGeN, SiSn, SiSnN, SiSnO, SiO, Ge, GeC, Any semiconductor of GeN may be used. In this case, these semiconductors may be crystalline or amorphous or microcrystalline containing at least one of hydrogen and fluorine.

Moreover, in the said embodiment, although the indium oxide (ITO) which doped Sn was used as a material which comprises a transparent conductive film, this invention is not restricted to this, The transparent conductive film which consists of materials other than ITO film | membrane is used. May be. For example, it was prepared by mixing an appropriate amount of at least one of Zn, As, Ca, Cu, F, Ge, Mg, S, Si and Te as a compound powder with indium oxide powder (In ₂ O ₃ ) and sintering. A transparent conductive film formed using a target may be used.

  Moreover, in the said embodiment, although the amorphous silicon layer was formed using RF plasma CVD method, this invention is not limited to this, Vapor deposition method, sputtering method, microwave plasma CVD method, ECR method, thermal CVD method The amorphous silicon layer may be formed using other methods such as LPCVD (low pressure CVD).

  Moreover, in the said embodiment, Ar gas was used at the time of sputtering of the ITO film | membrane which comprises a transparent conductive film, However, this invention is not restricted to this, He, Ne, Kr, other inert gas of Xe, or these It is also possible to use a mixed gas.

  Moreover, in the said embodiment, although the discharge operation | movement at the time of sputtering was performed using DC electric power, this invention is not limited to this, Pulse modulation DC discharge, RF discharge, VHF discharge, microwave discharge etc. are used. Also good.

It is the top view which showed the structure of the photovoltaic apparatus by one Embodiment of this invention. It is sectional drawing along the 100-100 line of FIG. It is an expanded sectional view of the adhesive layer vicinity of the photovoltaic device by one Embodiment shown in FIG. It is sectional drawing along the 200-200 line | wire of FIG. It is sectional drawing along the 300-300 line | wire of FIG. It is a figure for demonstrating the attachment process of the copper wire to the photoelectric conversion part of the photovoltaic apparatus by this embodiment. It is a figure for demonstrating the attachment process of the copper wire to the photoelectric conversion part of the photovoltaic apparatus by this embodiment. It is a figure for demonstrating the attachment process of the copper wire to the photoelectric conversion part of the photovoltaic apparatus by this embodiment. It is a figure for demonstrating the experiment conducted in order to confirm the effect by one Embodiment of this invention. It is sectional drawing for demonstrating the collector electrode of the photovoltaic apparatus by the 1st modification of one Embodiment of this invention. It is sectional drawing for demonstrating the collector electrode of the photovoltaic apparatus by the 2nd modification of one Embodiment of this invention. It is sectional drawing for demonstrating the contact bonding layer of the photovoltaic apparatus by the 3rd modification of one Embodiment of this invention. It is a figure for demonstrating the collector electrode of the photovoltaic apparatus by the 4th modification of one Embodiment of this invention. It is the top view which showed the structure of the photovoltaic apparatus by an example of the past. It is sectional drawing along the 400-400 line of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoelectric conversion part 2 Collector electrode 2a Recessed part 2b Copper wire (metal wire)
3 Adhesive layer 3a Granular filler (metal particles)
3b Flaky filler (metal particles)

Claims (7)

A photoelectric conversion unit;
A collector electrode attached to the main surface of the photoelectric conversion unit and made of a metal wire;
A conductive adhesive layer for adhering the collector electrode to the main surface of the photoelectric conversion unit;
A photovoltaic device, wherein an uneven shape is formed in at least a region of the collector electrode that is in contact with the adhesive layer.   The photovoltaic device according to claim 1, wherein the concave-convex shape of the collector electrode is provided with a plurality of concave portions. The adhesive layer contains metal particles,
3. The photovoltaic device according to claim 1, wherein the concave and convex portions of the collector electrode are filled with the metal particles of the adhesive layer.   The photovoltaic device according to claim 3, wherein an opening width of the concave portion of the concave-convex shape of the collector electrode is larger than a particle diameter of the metal particles of the adhesive layer. The collector electrode has a substantially circular cross-sectional shape;
The photovoltaic device of any one of Claims 1-4 in which the said uneven | corrugated shape is formed in the whole circumferential surface of the said collector electrode.   A plurality of the concave and convex concave portions of the collector electrode are provided at predetermined intervals along the outer periphery of a cross section intersecting with the extending direction of the collector electrode, and at predetermined intervals along the extending direction of the collector electrode. The photovoltaic device according to claim 1, wherein a plurality of the photovoltaic devices are provided. Forming a concavo-convex shape by a sandblasting method in a predetermined region of the metal wire;
A method of manufacturing a photovoltaic device, comprising: a step of forming a collector electrode by adhering a region of the metal wire with the uneven shape formed thereon to a main surface of a photoelectric conversion unit with a conductive adhesive layer. .

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