JP2000349318A - Solar battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery cell at a low cost, which has a structure wherein a metal substrate is used and generated power is led out from the back of the substrate, and is easily manufactured. SOLUTION: A lower electrode 4, a photoelectric converting layer 5 and a transparent electrode 6 are arranged in this order on the surface of a substrate 2 formed of metal. One lead-out electrode connected electrically with the transparent electrode 6, and the other lead-out electrode connected electrically with the lower electrode 4, are used. An insulating layer 3 exists between the substrate 2 and the lower electrode 4, and a penetrating hole 40A exists in a region in the substrate 2 on which region the lower electrode 4, photoelectric converting layer 5 and transparent electrode 6 are not present. A conductor rod 50A having flange parts on both sides exists in the penetrating hole 40A, and insulating coating 60A exists between the conductor rod and the substrate. The one flange part 51A is exposed to the surface side of the substrate 2 and connected with the transparent electrode 6, the other side flange part 52A is exposed to the back side of the substrate 2, and the conductor rod 50A functions as the one leading-out electrode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a solar cell.

[0002]

2. Description of the Related Art Solar cells are used in various electronic devices as a power source replacing dry cells and the like. In particular, low power electronic devices such as electronic desk calculators, clocks, portable electronic devices (cameras, mobile phones, consumer radar detectors), remote controllers, etc., can be sufficiently driven by the electromotive force of the solar cell. It has attracted attention because it does not require replacement and can be operated semi-permanently and is environmentally clean. Generally, an amorphous silicon (a-Si) layer or a microcrystalline S
An Si layer such as an i (μc-Si) layer is used.

[0003] A solar cell is constituted by laminating a lower electrode made of metal, a photoelectric conversion layer, and a transparent electrode on a surface of a rigid or flexible substrate. As the substrate, workability,
From the viewpoint of workability and the like, an organic flexible substrate which has flexibility and can be wound up and developed is often used. Usually, a Si layer formed by a plasma CVD method is used as the photoelectric conversion layer.

However, when a pattern is formed using a mask when a plasma CVD film is formed on an organic flexible substrate, the thermal contraction rate at the time of film formation differs due to the difference in expansion coefficient between the substrate and the plasma CVD film. Because of slip deformation
There is a problem that only the patterning portion swells like a drum. Such swelling tends to be more remarkable when a polymer material having a glass transition point (Tg) is used for the substrate. If the patterning portion swells, it becomes difficult to perform positioning, and it becomes difficult to form a multilayer using a mask. In addition, there is also an aesthetic problem that the appearance is poor when applied to a clock or a remote control when there is a climax. Incidentally, if a plasma CVD film is formed on the entire surface of the substrate without performing patterning, such a problem can be avoided.
Since it is necessary to perform patterning by laser processing or the like after the film is formed, the productivity is lower than in the case where patterning is performed simultaneously with the film formation by masking or the like, and the integration processing cost is increased.

[0005] Substrates used for solar cells include metal substrates in addition to organic flexible substrates. Since the metal substrate has better heat resistance than the organic flexible substrate, the temperature of the substrate can be increased when the plasma CVD film is formed. Therefore, the film formation rate and film characteristics are improved. Also, there is no occurrence of “warpage” or the like on the substrate. Further, even if the film is patterned during the plasma CVD, a drum-shaped swell does not occur.

[0006] However, since the metal substrate is conductive, if the lower electrode of each cell is directly provided thereon, the two are short-circuited, making it impossible to integrate a plurality of cells in series. Therefore, it is necessary to form an insulating layer between the lower electrode and the metal substrate.

[0007]

In a solar cell, it is necessary to provide a plus side extraction electrode and a minus side extraction electrode in order to extract generated power. In a small or portable electric / electronic device, for example, a remote controller, a calculator, a telephone, a clock, etc., it is necessary to take out electric power from the back side of the substrate for the convenience of mounting a solar cell.

When both of the pair of extraction electrodes are provided on the rear surface of the substrate, it is necessary to draw conductive paths from the transparent electrode and the lower electrode existing on the front surface of the substrate to the rear surface through the substrate, respectively, and to connect them to the extraction electrodes. is there. When using an organic flexible substrate that is an insulator, when forming one extraction electrode that is electrically connected to the transparent electrode, a through hole is simultaneously formed in the photoelectric conversion layer, the lower electrode, and the substrate by laser processing, and the through hole is formed. A conductive path can be easily formed by pouring a conductive paste into the hole from the transparent electrode surface side. In this case, the lower electrode in the through hole formation region is electrically insulated from the lower electrode in the power generation region. Also, for the other extraction electrode electrically connected to the lower electrode, a conductive path can be formed by similarly providing a through hole in the substrate.

On the other hand, when a metal substrate is used, if a conductive path is formed through the substrate, the transparent electrode and the lower electrode are short-circuited via the substrate. Further, in order to prevent such a short circuit, it is possible to insulate the inside of the through-hole and further form a conductive path with a conductive paste inside the through-hole. Ii) If the diameter of the through-hole is too small, a conduction failure occurs.iii) If the diameter of the through-hole is too large, the conductive paste leaks and spreads over the main surface of the substrate, which may cause a short circuit with the substrate. Problems arise. That is, in this method, the determination of the diameter of the through hole and the determination of the conductive paste injection condition are critical, and are not suitable for mass production.

An object of the present invention is to provide a solar cell having a metal substrate, having a structure for extracting generated power from the back side of the substrate, and being easy to manufacture and inexpensive.

[0011]

This and other objects are achieved by the present invention which is defined below as (1) to (6). (1) A lower electrode, a photoelectric conversion layer, and a transparent electrode are provided in this order on a surface of a substrate, and one extraction electrode electrically connected to the transparent electrode and the other extraction electrode electrically connected to the lower electrode. A solar cell having an extraction electrode,
The substrate is made of metal, and an insulating layer exists between the substrate and the lower electrode. In the substrate, the insulating layer exists, and the lower electrode, the photoelectric conversion layer, and the transparent electrode do not exist. A through hole exists in the region, a conductor bar having a flange at both ends is present in the through hole, an insulating coating exists between the conductor bar and the substrate, and one flange of the conductor bar is provided. Exposed on the front side of the substrate and electrically connected to the transparent electrode, the other flange of the conductor bar is exposed on the back side of the substrate, and the conductor bar is A solar cell that functions as an extraction electrode. (2) The solar cell according to the above (1), wherein the conductor bar is made of a metal, and at least one of the flanges is formed by crushing an end of the conductor bar. (3) The solar cell according to the above (1), wherein the conductor bar is made of metal, and at least one of the flanges is formed by expanding a cut provided at an end of the conductor bar. (4) A second conductor having a second through-hole in a region where the insulating layer is present and the lower electrode, the photoelectric conversion layer, and the transparent electrode are not present on the substrate, and a flange is provided at both ends. A rod is present in the second through-hole and the second
There is an insulating coating between the conductor bar and the substrate, one flange of the second conductor bar is exposed on the surface side of the substrate and is electrically connected to the lower electrode, A solar cell in which the other flange portion of the second conductor bar is exposed on the back side of the substrate, and the second conductor bar functions as the other extraction electrode. (5) the second conductor bar is made of metal;
The solar cell according to the above (4), wherein at least one of the flanges is formed by crushing an end of the second conductor bar. (6) the second conductor bar is made of metal;
(4) The solar cell according to the above (4), wherein at least one of the flange portions is formed by expanding a notch provided at an end of the second conductor bar.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a cross-sectional view mainly showing both ends of a solar cell according to the present invention.

The solar cell shown in FIG. 1 has a laminate in which a lower electrode 4, a photoelectric conversion layer 5 and a transparent electrode 6 are laminated in this order on the surface side of a substrate 2. The substrate 2 is made of a metal. Therefore, the insulating layer 3 is provided between the substrate 2 and the lower electrode 4. On one end side (left side in the figure) of the laminate, an interlayer insulating layer 9A exists between the photoelectric conversion layer 5 and the transparent electrode 6, and the separator insulating layer 10
A exists. The separator insulating layer 10A on the one end side
Has a separator 101A penetrating through the transparent electrode 6, the interlayer insulating layer 9A, the photoelectric conversion layer 5, and the lower electrode 4. One end of the laminate is insulated from the power generation region by the separator portion 101A.

On one end side of the substrate 2, a through hole 40A is provided in a region where only the insulating layer 3 is present, that is, in a region where the laminated body including the lower electrode 4, the photoelectric conversion layer 5 and the transparent electrode 6 is not present. Have been. This through hole 40A
Inside, a conductor rod 50A made of metal is inserted.
The conductor rod 50A has a flange 51A at one end and a flange 52A at the other end. An insulating coating 60A exists between the conductor bar 50A and the substrate 2. One flange 51A is exposed on the front surface side (upper side in the figure) of the substrate 2. The exposed portion and the transparent electrode 6 at the end of the power generation region are electrically connected by a conductive pad 7A. Conductor bar 50
The other flange 52A of A is exposed on the back side of the substrate 2. In this configuration, the conductor bar 50A functions as a plus-side extraction electrode.

On the other hand, at the other end of the solar cell, an interlayer insulating layer 9B exists between the photoelectric conversion layer 5 and the transparent electrode 6,
The separator insulating layer 10B exists on the transparent electrode 6. The separator insulating layer 10B on the other end side includes a separator portion 1 penetrating the transparent electrode 6, the interlayer insulating layer 9B and the photoelectric conversion layer 5.
01B. Except for the lower electrode 4, the other end of the stacked body is insulated from the power generation region by the separator 101B. The conductive pad 7B exists on the transparent electrode 6 on the end side of the separator portion 101B. The conductive pad 7B and the lower electrode 4 are electrically connected by a connection conductor 12B penetrating the photoelectric conversion layer 5 and the transparent electrode 6.

On the other end side of the substrate 2, a region where only the insulating layer 3 exists, that is, a region where the laminated body composed of the lower electrode 4, the photoelectric conversion layer 5 and the transparent electrode 6 does not exist, Through-hole (hereinafter simply referred to as through-hole)
40B are provided. In this through hole 40B, a second conductor bar (hereinafter simply referred to as a conductor bar) 5 made of metal is provided.
0B is inserted. The conductor bar 50B has a flange 51B at one end and a flange 52B at the other end. An insulating coating 60B is provided between the conductor bar 50B and the substrate 2.
Exists. One flange 51B is exposed on the front side (upper side in the figure) of the substrate 2. The exposed portion and the lower electrode 4 are electrically connected via the connection conductor 12B and the conductive pad 7B. The other flange 52 </ b> B of the conductor bar 50 </ b> B is exposed on the back side of the substrate 2. In this configuration, the conductor bar 50B functions as a minus extraction electrode.

In the configuration shown, the conductor bar 50A functions as one extraction electrode, and the conductor bar 50B functions as the other extraction electrode. Therefore, in this configuration, electric power can be extracted from the back surface side of the substrate 2. Moreover, as will be described later, the conductor bar can be easily fixed to the substrate in the same manner as the rivet, and it is easy to provide an insulating coating between the conductor bar and the substrate, which is excellent in mass productivity.

In the illustrated solar cell, light enters from the substrate surface side. The photoelectric conversion layer 5 is preferably a pin junction in which a p-type semiconductor layer, a photovoltaic layer (i-layer), and an n-type semiconductor layer are arranged in this order from the light incident side from the viewpoint of power generation efficiency. The rod 50A is taken out on the plus side,
The conductor bar 50B is shown as a minus extraction electrode. However, in the present invention, the order of lamination in the photoelectric conversion layer is not limited.

In the present invention, the other (minus side)
It is preferable that the extraction electrode is configured as in the illustrated example. However, the configuration is not limited to the illustrated example as long as power can be taken out from the rear surface side of the substrate, and another configuration may be used.
For example, by patterning when forming the photoelectric conversion layer 5 and the transparent electrode 6, the lower electrode 4 is exposed from the laminate on the right side in the figure, and the exposed lower electrode 4 is not directly connected to the conductor rod 50B. A configuration in which the connection is made indirectly via a conductive pad or the like may be adopted. Further, by exposing the surface of the substrate 2 on the end side from the exposed lower electrode 4 and providing a conductive pad covering the exposed portion and the lower electrode 4, the substrate 2 and the lower electrode 4 are electrically connected. Therefore, the substrate 2 itself can be used as the other extraction electrode. However, in this case, when mounting the solar cell, it is necessary to consider insulation between the circuit board and other electronic components.

Next, the configuration related to the extraction electrode will be described in detail.

The through holes 40A and 40B can be formed, for example, by mechanical processing of the substrate. The diameter of the through hole may be appropriately determined according to the diameter of the conductor rod and the thickness of the insulating coating.

It is preferable to use a metal as a constituent material of the conductor rods 50A and 50B, because it has good conductivity, is inexpensive, and can easily form a flange after being inserted into the through hole of the substrate. . In that case, after inserting the conductor bar having a flange at one end into the through hole of the substrate, the other end is crushed, whereby the flange can be easily formed at the other end. That is, the conductor bar can be fixed in the same manner as riveting.
In addition, as shown in FIG. 2, a flange 52A is provided at one end,
Conductor rod 5 provided with a longitudinal cut 55 at the other end
After inserting 0A into the through-hole 40A of the board 2, the notch 55 is pushed and widened, so that the flange 51A can be easily formed at the other end. In FIG. 2, the insulating layer 3
The illustration of the insulating coating 60A is omitted. Collar 52
A is preferably formed in advance as shown in the figure, but may be formed in the same manner as the flange 51A after the conductor bar is inserted. As the metal that constitutes the conductor bar,
For example, stainless steel, steel, copper, brass, and Al can be used. When made of metal, the diameter of the conductor bar is preferably 0.1 to 2 mm, more preferably 0.2 to 0.5 mm. If the conductor rod is too thin, sufficient conduction cannot be ensured, and the mechanical strength may be insufficient to cause disconnection, and it is difficult to form a flange. On the other hand, if the conductor bar is too thick, the substrate is likely to be deformed when the conductor bar is inserted to form a flange. In addition, when the flange is formed by crushing the end of the conductor bar, the flange becomes too thick.

The insulating coatings 60A and 60B may be formed near the outer peripheral surface of the conductor bar and / or near the inner peripheral surface of the through hole. Among them, the method of forming an insulating coating near the outer peripheral surface of the conductor bar is easy, and the increase in cost can be suppressed. The region where the insulating coating is formed may be appropriately determined so that the substrate and the conductive bar do not conduct. In addition, the constituent material of the insulating coating, the forming method, and the like are described later.
The same may be applied.

Next, a preferred configuration of each part other than the extraction electrode will be described with reference to FIG. FIG. 3 is a cross-sectional view mainly illustrating a central portion of the solar cell of the present invention.

In the solar cell shown in FIG. 1, an insulating layer 3, a lower electrode 4, a photoelectric conversion layer 5
And the transparent electrode 6 in this order.

The illustrated solar cell has a configuration in which a plurality of solar cells each having a light receiving surface are connected in series.
A collecting / wiring electrode 11 is provided on the transparent electrode 6 of each cell. The illustrated collecting / wiring electrode 11 is a connecting portion between the collecting electrode and the wiring electrode. The collecting electrode is an electrode for collecting the electric power generated in each cell from the surface of the transparent electrode 6 having a relatively high specific resistance. The wiring electrode is an electrode for connecting the collection electrode of each cell to the lower electrode of an adjacent cell. In the illustrated example, the collecting / wiring electrode 11
, A connection conductor 12 extends through the transparent electrode 6 and the photoelectric conversion layer 5 and is connected to the lower electrode 4 of an adjacent cell, whereby the adjacent cells are connected in series. An interlayer insulating layer 9 exists between the transparent electrode 6 and the collecting / wiring electrode 11, and the transparent electrode 6 is provided on the interlayer insulating layer 9.
The separator insulating layer 10 exists between the two. In the illustrated example, the separator portion 101 of the separator insulating layer 10 extends through the transparent electrode 6, the photoelectric conversion layer 5, and the lower electrode 4, and insulates the lower electrodes of adjacent cells. The separator part 101 is a wall-shaped body that also extends in the depth direction in the figure.

At both ends of the series connection, as shown in FIG. 1, plus and minus extraction electrodes are provided, respectively.

Although not shown, it is preferable to provide a sealing member on at least the surface on the transparent electrode 6 forming side of the illustrated solar cell in order to suppress mechanical damage, oxidation, corrosion and the like of the solar cell. Further, such a sealing member is preferably provided also on the back surface side of the substrate 2.

Hereinafter, the configuration of each section will be described in detail.

Substrate The substrate 2 is made of metal. The material for forming the substrate is not particularly limited. For example, Cu, Al or Ni, or an alloy containing at least two of these, stainless steel (for example, SUS301, SUS304,
SUS430), an Fe-Ni alloy, an Fe-Ni-Cr alloy, or the like can be used. Among these, SU
It is preferable to use S304 or SUS430.

The thickness of the substrate is not particularly limited.
It is about 20 to 150 μm.

The insulating layer and the insulating coating insulating layer 3 are provided to insulate the substrate and the lower electrode.

The material constituting the insulating layer 3 and the insulating coatings 60A and 60B is not particularly limited as long as it has electrical insulation, and may be any of an inorganic material and an organic material.

Examples of the inorganic material include, for example, any one of silicon oxide, silicon nitride, silicon carbide, and aluminum oxide, or a compound containing two or more of these components. And / or those containing silicon nitride as a main component are preferred. When composed of an inorganic material, the thickness of the insulating layer and the insulating coating is preferably from 0.1 nm to 5 μm, more preferably from 0.5 nm to 3 μm. The insulating layer and the insulating coating made of an inorganic material can be formed by, for example, a sol-gel method,
It can be formed by any of the VD method, the sputtering method, and the like.

As the organic material, various resins, in particular,
A resin having high heat resistance is preferable, and specifically, for example, polyimide, polybenzimidazole, and polyamideimide are preferable, and among these, polyimide is particularly preferable. When composed of an organic material, the thickness of the insulating layer and the insulating layer is preferably 0.1 to 20 μm, more preferably 1 to 10 μm. The insulating layer and insulating coating made of an organic material can be formed by vapor deposition, but are preferably formed by coating, and then dried and cured as necessary.

It is not necessary that the insulating layer and the insulating coating are made of the same material.

Lower Electrode The lower electrode 4 is made of metal. The material for the lower electrode is not particularly limited. For example, Al or stainless steel may be used, but Al is preferably used. Since Al has a low specific resistance, deterioration due to energy loss and heat generation is small. By the way, in the solar cell, the light reflected by the lower electrode through the photoelectric conversion layer enters the photoelectric conversion layer again, and this reflected light is also converted into electric energy. Therefore, it is preferable that the lower electrode has a high reflectance, but Al having a high light reflectance is also excellent in this respect. Further, Al has high thermal conductivity, good corrosion resistance, and is inexpensive.

The thickness of the lower electrode is not particularly limited, but is preferably 0.01 to 10 μm. The lower electrode is preferably formed by a vapor deposition method such as a sputtering method.

A diffusion preventing layer is provided between the lower electrode 4 and the photoelectric conversion layer 5 to prevent the constituent components of the lower electrode from diffusing into the photoelectric conversion layer. It is preferable to provide a diffusion prevention layer made of a metal such as Ti or Cr. The thickness of the diffusion preventing layer is preferably 3 to 5 nm. The diffusion preventing layer may be usually formed by a vapor deposition method such as a sputtering method.

Photoelectric Conversion Layer The photoelectric conversion layer 5 is preferably made of single crystal silicon, microcrystalline silicon or amorphous silicon having a pn junction or a pin junction, preferably a pin junction. A pn junction or a pin junction can be formed by adding a predetermined impurity when forming the photoelectric conversion layer.

Hereinafter, a photoelectric conversion layer in which an n-type semiconductor layer made of amorphous silicon or microcrystalline silicon, a photovoltaic layer (i-layer), and a p-type semiconductor layer are stacked will be described.

B is preferably an impurity for forming a p-type semiconductor layer.
Preferably, its content is 10¹⁷-10 ²⁰atoms / cm^ThreeIs
Is preferred. Impurity content too low or too high
Also, the energy conversion efficiency is reduced.

P is preferably an impurity for forming an n-type semiconductor layer.
Preferably, its content is 10¹⁷-10 ²⁰atoms / cm^ThreeIs
Is preferred. Impurity content too low or too high
Also, the energy conversion efficiency is reduced.

The thickness of each layer is not particularly limited, but is preferably 5 to 40 nm for a p-type semiconductor layer, preferably 100 to 20 μm for an i-layer, and preferably 5 to 40 nm for an n-type semiconductor layer.

Usually, such a photoelectric conversion layer is preferably formed by a plasma CVD method. Plasma CV
The plasma in the method D may be either DC or AC, but AC plasma is preferably used. The AC plasma can be used at a frequency of several hertz to several gigahertz.

The p-type semiconductor layer is made of SiH ₄ , H ₂ , B
_{Using 2} H ₆ or the like, the flow rate ratio B ₂ H ₆ / SiH ₄ is determined according to the target impurity content, and the substrate temperature is changed from room temperature to 450 ° C.
° C, preferably 200-300 ° C, operating pressure of 0.01
10 to Torr, input power 10 to 2000 W (frequency 10 ⁶
To 10 ⁹ Hz) may be formed as a.

The i-layer is formed by using SiH ₄ , H ₂ or the like as a raw material, at a flow rate of 1 to 2000 sccm, and at a substrate temperature of room temperature to 45 ° C.
0 ° C., preferably 260-380 ° C., operating pressure of 0.0
What is necessary is just to form it at 1-10 Torr and input electric power at 10-2000 W.

The n-type semiconductor layer is made of SiH ₄ , H ₂ , P
Using H ₃ or the like, the flow rate ratio PH ₃ / SiH ₄ is determined according to the target impurity content, and the substrate temperature is changed from room temperature to 450 ° C.
Preferably at 250-350 ° C, operating pressure 0.01-1.
What is necessary is just to form it as 0 Torr and input power 10-2000W.

The constituent material of the transparent electrode transparent electrode 6 is not particularly limited, transparency,
Good conductivity, tin oxide, ITO
(Indium tin oxide) and ZnO are preferred. The thickness of the transparent electrode is not particularly limited, but is usually preferably 10 to 100 nm. The transparent electrode made of the above material is usually formed by a vapor phase growth method such as a sputtering method.

Interlayer insulating layer, separator insulating layer Interlayer insulating layer 9 and separator insulating layer 1 in the illustrated example
The material constituting 0 is not particularly limited as long as it has an insulating property and can form the structure shown in the figure, but it is usually preferable to use an insulating resin. As the insulating resin, for example, a urethane resin, a phenoxy resin, or the like is preferable. The interlayer insulating layer 9 and the separator insulating layer 10
May be composed of the same material or different materials.

The thickness of the interlayer insulating layer 9 is preferably 5 to 40 μm, and the thickness of the flat portion of the separator insulating layer 10 is preferably 5 to 10 μm.

The interlayer insulating layer and the separator insulating layer may be usually formed by a coating method such as screen printing.
Interlayer insulating layer 9 and separator insulating layer 1 in the illustrated example
0 is usually formed by the following procedure. First, after forming the photoelectric conversion layer 5, the interlayer insulating layer 9 is formed in a predetermined pattern by screen printing or the like. Next, the interlayer insulating layer 9
After the transparent electrode 6 is formed thereon, a groove penetrating the transparent electrode 6, the interlayer insulating layer 9, the photoelectric conversion layer 5, and the lower electrode 4 is formed by, for example, laser processing. The laminated body from the lower electrode 4 to the transparent electrode 6 is divided by the groove and separated into cells. Next, the separator insulating layer 1 is formed on the transparent electrode 6.
0 is formed in a predetermined pattern by screen printing or the like. At this time, the insulating material penetrates into the groove, and the separator part 101 is formed.

The interlayer insulating layer 9 is provided to prevent a short circuit between the transparent electrode 6 and the lower electrode 4 at the time of forming the separator portion 101. In addition, the interlayer insulating layer 9 also has a function of improving the breakdown voltage of the solar cell. For example, if a minute defect or inhomogeneity exists in the photoelectric conversion layer 5, the lower electrode 4 is located at that position.
Although a short circuit may occur between the first electrode and the transparent electrode 6, the provision of the interlayer insulating layer 9 forms a capacitor having a relatively high capacitance, so that occurrence of such dielectric breakdown can be prevented.

The interlayer insulating layers 9A and 9B and the separator insulating layers 10A and 10B shown in FIG. 1 are formed in the same thickness as the interlayer insulating layer 9 and the separator insulating layer 10 shown in FIG. I just need.

The constituent materials of the collecting / wiring electrode, the connecting conductor, and the conductive pad collecting / wiring electrode 11 are not particularly limited.
Usually, it is preferable to use Ag. The thickness of the collecting / wiring electrode is preferably 5 to 10 μm.

The collecting / wiring electrodes may be usually formed by a coating method such as screen printing. In the illustrated example, the collecting / wiring electrode 11 is usually formed in the following procedure. First, after forming the separator insulating layer 10, the collecting / wiring electrode 11 is formed in a predetermined pattern by screen printing or the like. Next, in a region where the interlayer insulating layer 9 does not exist, the collecting / wiring electrode 11 is pierced by, for example, laser processing, and the lower electrode 4 penetrates the transparent electrode 6 and the photoelectric conversion layer 5.
To form holes. At the time of this perforation, the constituent material of the collecting / wiring electrode 11 is melted and penetrates into the hole, and the connection conductor 12 is formed.

The connection conductor 12B shown in FIG.
Can be formed in the same manner as the connection conductor 12 shown in FIG. The conductive pads 7A and 7B shown in FIG. 1 can be formed in a predetermined pattern by screen printing or the like, similarly to the collecting / wiring electrode 11. The thickness of the conductive pads 7A and 7B is preferably 5 to 10 μm.

[0058] The sealing member mechanical damage, oxide, as the sealing member for suppressing corrosion, the resin film is preferable. The resin film may be formed by coating or sticking. The sealing member is preferably provided at least on the surface on the transparent electrode 6 side, more preferably on the back surface side of the substrate 2.

Hereinafter, an example of a method for forming a resin film by sticking will be described. In this example, a sealing member in which a buffer adhesive layer containing a thermosetting resin is provided on at least one surface of a resin base material having a light transmitting property and a heat resistance property is used.

The glass substrate has a glass transition point Tg of 65 ° C.
Or the heat-resistant temperature (or continuous use temperature) is 80
C. or higher, or a resin film that satisfies both of these conditions and has translucency. Such a resin film does not deteriorate in performance even when it is directly exposed to a light source such as sunlight and heated.

As a resin base material having a glass transition point Tg of 65 ° C. or higher and / or a heat-resistant temperature of 80 ° C. or higher, a polyethylene terephthalate film (Tg6
9 ° C), polyethylene naphthalate heat-resistant film (Tg
113 ° C.); ethylene trifluorochloride resin [PCTFE:
NEOFLON CTFE (manufactured by Daikin Industries, Ltd.)] (heat-resistant temperature 150 ° C.), polyvinylidene fluoride [PVDF:
Denka DX film (manufactured by Denki Kagaku Kogyo Co., Ltd.)] (heat-resistant temperature 150 ° C .: Tg 50 ° C.), polyvinyl fluoride [P
VF: Tedlar PVF film (manufactured by DuPont)] (heat-resistant temperature: 100 ° C.) or a fluoride homopolymer or ethylene tetrafluoride-perfluorovinyl ether copolymer [P
FA: Neoflon: PFA film (manufactured by Daikin Industries, Ltd.)] (heat resistant temperature: 260 ° C.), ethylene tetrafluoride-hexafluoropropylene copolymer [FEP: Toyofuron film FEP type (manufactured by Toray Industries, Inc.)] ° C), tetrafluoroethylene-ethylene copolymer [ETFE: Tefzel ETFE film (manufactured by DuPont) (heat resistant temperature 150
° C), AFLEX film (manufactured by Asahi Glass Co., Ltd .: Tg83)
℃)] or other fluorine-based film; aromatic dicarboxylic acid-bisphenol copolymerized aromatic polyester [PAR: casting (ELMEC manufactured by Kaneka Chemical Co., Ltd.)] (heat-resistant temperature: 290 ° C .: Tg 215 ° C.) Acrylate film; polysulfone [PSF:
Sumilite FS-1200 (Sumitomo Bakelite)
(Tg 190 ° C.), polyether sulfone [PES: Sumilite FS-1300 (Sumitomo Bakelite)] (Tg
Polycarbonate film [PC: Panlite (manufactured by Teijin Chemicals Ltd.)]
(Tg 150 ° C); functional norbornene resin [ARTON (manufactured by JSR)] (heat-resistant temperature 164 ° C:
Tg 171 ° C.); polymethyl methacrylate (PMM
A) (Tg 93 ° C); olefin-maleimide copolymer [TI-160 (manufactured by Tosoh Corporation)] (Tg 150 ° C or more), para-aramid [Aramica R: manufactured by Asahi Kasei Corporation] (heat-resistant temperature 200 ° C), fluorinated polyimide (heat-resistant) Temperature 200 ° C
Above), polystyrene (Tg 90 ° C), polyvinyl chloride (Tg 70-80 ° C), cellulose triacetate (Tg
g 107 ° C).

Among these, the polyethylene naphthalate heat-resistant film (Tg 113 ° C.) has a higher heat resistance (Tg), heat resistance during long-term use, Young's modulus (stiffness), breaking strength, and heat shrinkage rate than the polyethylene terephthalate film. , Low oligomers, excellent gas barrier properties, hydrolysis resistance, water vapor transmission rate, thermal expansion coefficient, physical property deterioration due to light, etc., and breaking strength compared to other polymers , Heat resistance, dimensional stability, moisture permeability,
Because it is excellent in terms of total balance such as cost,
preferable.

The glass transition point Tg of the resin substrate is preferably at least 65 ° C., more preferably at least 70 ° C., further preferably at least 80 ° C., particularly preferably at least 110 ° C. Although the upper limit of Tg is not particularly limited, it is usually 130 ° C.
It is about. Further, the heat resistant temperature or the continuous use temperature is preferably 80 ° C. or more, more preferably 100 ° C. or more, and further preferably 110 ° C. or more. The higher the heat resistance temperature or the continuous use temperature, the better, and the upper limit is not particularly limited, but is usually about 250 ° C.

The thickness of the resin substrate may be appropriately determined according to the structure of the solar cell, the strength and bending rigidity required of the resin substrate, etc., and is usually 5 to 100 μm.

The transmissivity of the resin substrate is preferably such that 70% or more, particularly 80% or more of the light in the visible light region is transmitted.

The buffer adhesive layer preferably contains a thermosetting resin component and an organic peroxide before thermocompression bonding.

As the thermosetting resin component, ethylene-vinyl acetate copolymer [EVA (vinyl acetate content of 15 to
About 50%)].

Examples of the organic peroxide include 2,5-dimethylhexane-2,5-dihydroperoxide;
2,5-dimethyl-2,5-di (t-butylperoxy) hexane-3; di-t-butyl peroxide;
2,5-dimethyl-2,5-di (t-butylperoxy) hexane; dicumyl peroxide; α, α′-bis (t-butylperoxyisopropyl) benzene; n
-Butyl-4,4-bis (t-butylperoxy) valerate; 2,2-bis (t-butylperoxy) butane; 1,1-bis (t-butylperoxy) -3,3
5-trimethylcyclohexane; t-butylperoxybenzate; benzoyl peroxide can be used. These may be used alone or in combination of two or more, and the combination ratio when using in combination is arbitrary. The amount of the organic peroxide to be used per 100 parts by weight of the thermosetting resin component is preferably 10 parts by weight or less, more preferably 0.5 to 6 parts by weight.

The thickness of the buffer adhesive layer may be appropriately determined according to the structure of the solar cell, the use environment, and the like, but is preferably 3 to 500 μm, more preferably 3 to 50 μm, and still more preferably 10 to 40 μm. . If the buffer adhesive layer is too thin, the buffer effect will be insufficient. On the other hand, when the buffer adhesive layer is too thick, the light transmittance is reduced, and burrs are easily generated at the time of punching or the like. However, since the buffer adhesive layer has much better light transmittance than the resin base material, when used under high illuminance such as outdoors, there may be no problem even if the thickness is increased to about 10 mm.

As means for providing the buffer adhesive layer on the resin substrate, known means such as coating or extrusion coating can be used.

The buffer adhesive layer may be embossed. When laminating the sealing member to the solar cell,
If embossing is performed so that a passage for bubbles is formed, mixing of bubbles is reduced.

Next, an example of a method for forming a resin film by coating will be described.

The resin film formed by the coating method is slightly inferior in flatness, weather resistance and the like as compared with the above-mentioned resin film formed by sticking. However, the resin film is used by being incorporated in equipment or used mainly for indoor use. If you do, there is no problem. In the application method,
Since the laminating step and the subsequent flattening step required in the above-mentioned attaching method can be omitted, the manufacturing cost can be reduced.

The resin used in this case has excellent transparency,
It is preferable that there is little discoloration due to aging and light deterioration, and particularly preferable is a thermosetting resin. As the thermosetting resin, for example, a fluorine resin, polyurethane, polyester, epoxy resin, and phenoxy resin can be used.

The resin coating may be formed by a screen printing method, a spin coating method, or the like.

[0076]

EXAMPLE A solar cell having the structure shown in FIGS. 1 and 3 was manufactured by the following procedure.

A metal substrate 2 (230 mm in length, 360 mm in width, and 50 μm in thickness) made of SUS430 was prepared, and through holes 40 A and 40 B having a diameter of 0.5 μm were formed in this substrate by machining.

Next, a polyimide coating agent (U-imide type B manufactured by Unitika) is applied to the entire surface of one surface of the substrate by a roll coating method, and is kept at 170 ° C. for 10 minutes and then at 350 ° C. for 60 minutes. Thus, the coating film was cured, and an insulating layer 3 having a thickness of 6 μm was obtained.

Next, as the conductor rods 50A and 50B, straight Al rods (diameter 0.4 mm) having a flange (diameter 1.2 mm) at one end were prepared. Then, except for the top surface of the flange portion of these conductor rods, as shown in FIG.
0A and 60B were formed. The insulating coating was formed by dipping a conductor bar in a polyimide coating agent. Next, as shown in FIG.
The top surface of the other end was exposed by cutting the end portion on the other end side (upper side in the figure) of 0B. Next, after inserting these conductor rods into the through holes 40A and 40B from the back side of the substrate 2, the other end side was crushed to form the other flange (about 1.0 mm in diameter).

Next, a lower electrode 4 made of Al and having a thickness of 0.3 μm was formed on the insulating layer 3 by sputtering, and a diffusion preventing layer made of stainless steel and having a thickness of 5 nm was formed thereon. . When forming the lower electrode 4 and each layer above it, patterning was performed so as not to cover the through holes 40A and 40B.

Next, a photoelectric conversion layer 5 was formed on the diffusion preventing layer by the following procedure. First, an n-type microcrystalline silicon layer was formed to a thickness of 20 nm by a plasma CVD method. At this time, the raw material gas and its flow rate were: PH ₃ + H ₂ mixed gas (PH ₃ / H ₂ = 0.2%): 30 sc
cm, SiH ₄ : 4 sccm, H ₂ : 750 sccm, and other conditions were as follows: substrate temperature: 300 ° C., operating pressure: 1 Torr, input power: 100 W (13.56 MHz). Subsequently, the i-type amorphous silicon layer is
It was formed to a thickness of 0 nm by a plasma CVD method. At that time, the source gas and its flow rate were SiH ₄ : 50 sccm, H ₂ : 500 sccm, and other conditions were: substrate temperature: 260 ° C., operating pressure: 1 Torr, input power: 100 W (13.56 MHz). Subsequently, a p-type microcrystalline silicon layer was formed to a thickness of 20 nm by a plasma CVD method. At this time, the raw material gas and the flow rate thereof are B ₂ H ₆ + H ₂ mixed gas (B ₂ H ₆ / H ₂ = 0.2%): 30
sccm, SiH ₄ : 5 sccm, H ₂ : 950 sccm, and other conditions were: substrate temperature: 280 ° C., operating pressure: 1 Torr, input power: 200 W (13.56 MHz).

Next, a urethane-based insulating resin composition was printed in a predetermined pattern on the photoelectric conversion layer 5 by a screen printing method, and then left standing in an oven at 160 ° C. for 10 minutes to be cured, and the thickness was 20 μm. Interlayer insulating layers 9, 9A, 9B
And

Next, a transparent electrode 6 having a thickness of 60 nm was formed by sputtering in an Ar atmosphere using ITO (indium tin oxide) as a target.

Then, grooves are formed by laser scribing, and a urethane insulating resin composition is screen-printed thereon to thereby form separator insulating layers 10, 10A and 10B having a thickness of 10 μm and having separator portions 101, 101A and 101B, respectively. Was formed.

Next, the silver paste is screen-printed and cured to form a collecting / wiring electrode 11 (6 μm thick).
), Connection conductors 12 and 12B, conductive pads 7A and 7B
(Thickness: 6 μm) to obtain a solar cell sample.

The sample was irradiated with 100 mW / cm ² light by a solar simulator. As a result, no short circuit was observed inside the sample, a photocurrent of 13.2 mA / cm ² was obtained, and it was confirmed that sufficient characteristics as a solar cell were obtained.

As the conductor rods 50A and 50B, a straight Al rod (0.4 m in diameter) having a flange (diameter 1.2 mm) at one end and one notch crossing the radial direction at the other end.
m) was prepared. Then, a solar cell sample was obtained in the same manner as in the above sample, except that the notch was spread out by using the conductor bar and swaging to form the flange at the other end. When the photocurrent of this sample was measured in the same manner as in the above sample, no short circuit was observed inside the sample, and a photocurrent of 13.2 mA / cm ² was obtained.
It was confirmed that sufficient characteristics were obtained as a solar cell.

[0088]

According to the present invention, a solar cell having a metal substrate and having a structure in which generated power is extracted from the back side of the substrate can be obtained easily and at low cost.

[Brief description of the drawings]

FIG. 1 is a sectional view showing the vicinity of both ends of a solar cell of the present invention.

FIG. 2 is a diagram illustrating a method of forming a flange on a conductor bar.

FIG. 3 is a sectional view showing the vicinity of the center of the solar cell of the present invention.

FIG. 4 is a cross-sectional view for explaining a step of forming an insulating coating on a conductor bar.

[Explanation of symbols]

 2 Substrate 3 Insulating layer 4 Lower electrode 5 Photoelectric conversion layer 6 Transparent electrode 7A, 7B Conductive pad 9, 9A, 9B Interlayer insulating layer 10, 10A, 10B Separator insulating layer 101, 101A, 101B Separator section 11 Collection / wiring electrode 12, 12B Connection conductor 40A, 40B Through hole 50A, 50B Conductor rod 51A, 51B, 52A, 52B Flange 55 Cut 60A, 60B Insulation coating

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toru Kineri 1-13-1 Nihombashi, Chuo-ku, Tokyo TDC Corporation F-term (reference) 5F051 EA01 EA17 FA13 FA14 FA15 FA17 FA30 GA02 GA06

Claims (6)

[Claims] 1. A lower electrode, a photoelectric conversion layer, and a transparent electrode are provided in this order on a surface of a substrate, and one extraction electrode electrically connected to the transparent electrode is electrically connected to the lower electrode. A solar cell having the other extraction electrode, wherein the substrate is made of metal, an insulating layer is present between the substrate and the lower electrode, and the insulating layer is present on the substrate, and A through hole exists in a region where the lower electrode, the photoelectric conversion layer and the transparent electrode do not exist, and a conductor rod having a flange at both ends exists in the through hole, and an insulating coating is provided between the conductor rod and the substrate. Is present, one of the flanges of the conductor bar is exposed on the front side of the substrate and is electrically connected to the transparent electrode, and the other flange of the conductor bar is on the back side of the substrate. And the conductor bar is exposed to the one Solar cells, which functions as an electrode Eject and. 2. The conductor rod is made of metal,
The solar cell according to claim 1, wherein at least one of the flanges is formed by crushing an end of a conductor bar. 3. The conductor rod is made of metal,
The solar cell according to claim 1, wherein at least one of the flange portions is formed by pushing out a cut provided at an end of the conductor bar. 4. A second through hole having a second through hole in a region where the insulating layer is present and the lower electrode, the photoelectric conversion layer and the transparent electrode are not present on the substrate, and a second through hole is provided at both ends. Conductor rod is present in the second through-hole, an insulating coating exists between the second conductor rod and the substrate, and one flange of the second conductor rod is Exposed on the surface side and electrically connected to the lower electrode,
A solar cell in which the other flange of the second conductor bar is exposed on the back side of the substrate, and the second conductor bar functions as the other extraction electrode. 5. The second conductor bar is made of a metal, and at least one of the flanges is formed by crushing an end of the second conductor bar.
Solar cell. 6. The second conductor bar is made of metal, and at least one of the flanges is formed by pushing out a notch provided at an end of the second conductor bar. The solar cell according to claim 4.