JP2014011320A - Solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin-film solar cell module which less deteriorates during manufacture thereof.SOLUTION: The solar cell module includes a solar cell comprising: a solar cell element in which a photoelectric conversion layer 7, a substrate 1 for supporting the photoelectric conversion layer 7, and at least one pair of electrodes 2 and 6 connected to the photoelectric conversion layer 7 at the light receiving surface side and the non-light receiving surface side of the photoelectric conversion layer 7 are laminated; and at least one pair of current collecting wires 8 connected to the electrodes 2 and 6. The current collecting wires 8 are connected to the electrodes 2 and 6 via a conductive adhesive 9.

Description

  The present invention relates to a solar cell module.

  A thin-film solar cell module manufactures a thin-film solar cell element including a photoelectric conversion layer, and an upper electrode and a lower electrode, and connects each electrode of the thin-film solar cell element and a collector wire for sealing. Manufactured by. In general, the thin-film solar cell element has a monolithic structure in which a plurality of solar cells are connected in series in order to adjust a necessary potential and improve manufacturing efficiency.

  In order to take out electricity from the thin film solar cell element, usually, each solar battery cell forming the thin film solar cell element is used for taking out electricity at a portion that does not overlap the photoelectric conversion layer, particularly at both ends of the thin film solar cell element. An electrode is installed, and the electrode and a collector line are connected (for example, see Patent Documents 1 and 2). On the other hand, since the thin film solar cell element is vulnerable to water and oxygen, a material having a high gas barrier property is used as a material for protecting the organic layer.

JP 2011-124582 A JP 2011-171707 A

  When the present inventors examined a method of connecting the electrode and the current collector, when a connection with a thermosetting conductive adhesive was tried, the power generation layer deteriorated due to the heat applied during curing, and the solar The power generation efficiency of the battery is lowered, and further, the shrinkage when the thermosetting adhesive is cured, stress is applied to the solar cell, the power generation layer is deformed, the module performance is deteriorated due to damage, It was also discovered that the module performance deteriorates by destroying the electrode of the organic thin film solar cell.

  This invention solves such a subject, and makes it a subject to provide a thin film solar cell module with little deterioration of the module at the time of solar cell module manufacture.

  Therefore, as a result of intensive studies to solve the above problems, the present inventors have at least a photoelectric conversion layer, a substrate supporting the photoelectric conversion layer, a light receiving surface side and a non-light receiving surface of the photoelectric conversion layer. In a solar cell module comprising a solar cell having a solar cell element in which at least a pair of electrodes connected to the photoelectric conversion layer on the side is laminated, and at least a pair of current collectors connected to the electrodes, the current collector is The inventors have found that the above problem can be solved by connecting to the electrode via a conductive adhesive, and completed the present invention. The outline of the present invention is as follows.

  The present invention relates to a solar cell in which at least a photoelectric conversion layer, a substrate that supports the photoelectric conversion layer, and at least a pair of electrodes that are connected to the photoelectric conversion layer on a light receiving surface side and a non-light receiving surface side of the photoelectric conversion layer are stacked. In a solar cell module comprising a solar cell having a battery element and at least a pair of current collectors connected to the electrodes, the current collectors are connected to the electrodes via a conductive adhesive. It is a solar cell module.

  Moreover, it is preferable that the thickness of the said current collection line is 200 micrometers or less.

  ADVANTAGE OF THE INVENTION According to this invention, the thin film solar cell module with little deterioration of the module at the time of solar cell module manufacture can be obtained.

It is a figure for demonstrating the monolithic structure of a solar cell. It is the conceptual diagram shown about the one aspect | mode of the solar cell module of this invention.

The present invention will be specifically described below.
The present invention includes at least a photoelectric conversion layer, a substrate supporting the photoelectric conversion layer, and at least a pair of electrodes (an upper electrode and a lower electrode) connected to the photoelectric conversion layer on a light receiving surface side and a non-light receiving surface side of the photoelectric conversion layer. In a solar cell module comprising a solar cell having a solar cell element on which an electrode) is stacked and at least a pair of current collectors connected to the electrode, the current collector is connected to the electrode via a conductive adhesive. It is connected.

<Solar cell element>
As the solar cell element used in the solar cell module of the present invention, any element may be used as long as the effect of the present invention is not impaired, but thin film single crystal silicon, thin film polycrystalline silicon, amorphous silicon, It is preferable to use silicon-based semiconductor materials such as microcrystalline silicon and spherical silicon, compound semiconductor materials such as CIS, CIGS, and GaAs, organic dye materials, and organic semiconductor materials. Among these, it is particularly preferable to use an organic semiconductor material because it is particularly excellent in productivity and meets the object of the present invention. Hereinafter, the case of an organic thin film solar cell element using an organic semiconductor material will be described.

(Photoelectric conversion layer)
The photoelectric conversion layer is formed of an organic semiconductor. Organic semiconductors are classified into p-type and n-type depending on semiconductor characteristics. The p-type and n-type indicate whether it is a hole or an electron that contributes to electrical conduction, and depends on the electronic state, doping state, and trap state of the material. Therefore, there are cases where p-type and n-type cannot always be clearly classified, and there are cases where the same substance exhibits both p-type and n-type characteristics.

  Examples of p-type semiconductors include porphyrin compounds such as tetrabenzoporphyrin, tetrabenzocopper porphyrin, tetrabenzozinc porphyrin; phthalocyanine compounds such as phthalocyanine, copper phthalocyanine, zinc phthalocyanine; naphthalocyanine compounds; polyacenes of tetracene and pentacene; Examples thereof include oligothiophene and derivatives containing these compounds as a skeleton. Furthermore, polymers such as polythiophene, polyfluorene, polyphenylene vinylene, polytriallylamine, polyacetylene, polyaniline, polypyrrole and the like including poly (3-alkylthiophene) are exemplified.

  Examples of n-type semiconductors include fullerene (C60, C70, C76); octaazaporphyrin; perfluoro compound of the above p-type semiconductor; naphthalenetetracarboxylic acid anhydride, naphthalenetetracarboxylic acid diimide, perylenetetracarboxylic acid anhydride, perylene. And aromatic carboxylic acid anhydrides such as tetracarboxylic acid diimide and imidized products thereof; and derivatives containing these compounds as a skeleton.

The specific structure of the photoelectric conversion layer is arbitrary as long as at least a p-type semiconductor and an n-type semiconductor are contained. The photoelectric conversion layer may be constituted only by a single layer film or may be constituted by two or more laminated films. For example, an n-type semiconductor and a p-type semiconductor may be contained in separate films, or an n-type semiconductor and a p-type semiconductor may be contained in the same film. In addition, each of the n-type semiconductor and the p-type semiconductor may be used alone or in combination of two or more in any combination and ratio.

  As a specific configuration example of the photoelectric conversion layer, a bulk heterojunction type having a layer (i layer) in which a p-type semiconductor and an n-type semiconductor are phase-separated in the layer, a layer containing a p-type semiconductor (p layer) and n, respectively. Examples include a stacked type (hetero pn junction type) in which a layer containing a type semiconductor (n layer) has an interface, a Schottky type, and a combination thereof. Among these, a bulk heterojunction type and a combination of a bulk heterojunction type and a stacked type (p-i-n junction type) are preferable because they exhibit high performance.

  The thickness of each layer of the p-layer, i-layer, and n-layer of the photoelectric conversion layer is usually 3 nm or more, preferably 10 nm or more, and usually 500 nm or less, preferably 50 to 300 nm. Increasing the thickness tends to increase the photocurrent, and decreasing the thickness tends to decrease the series resistance.

(electrode)
The lower electrode and the upper electrode can be formed of a conductive material, for example, a metal such as platinum, gold, silver, aluminum, chromium, nickel, copper, titanium, magnesium, calcium, barium, sodium, or the like Alloys thereof; metal oxides such as indium oxide, tungsten oxide, and tin oxide, or composite oxides thereof (ITO, IWO, IZO, etc.); conductive polymers such as polyaniline, polypyrrole, polythiophene, and polyacetylene; Molecules containing dopants such as acids such as hydrochloric acid, sulfuric acid, sulfonic acid, Lewis acids such as FeCl ₃ , halogen atoms such as iodine, metal atoms such as sodium and potassium; metal particles, carbon black, fullerene, Conductive particles such as carbon nanotubes and polymer binders And conductive composite materials dispersed in the matrix.
Among these, a material having a deep work function such as Au or ITO is preferable for the electrode for collecting holes. On the other hand, for the electrode for collecting electrons, a material having a shallow work function such as Al is preferable. By optimizing the work function, there is an advantage of favorably collecting holes and electrons generated by light absorption.

  At least the electrode on the light-receiving surface side has optical transparency and is preferably transparent. However, the electrode is not necessarily transparent if it does not significantly adversely affect the power generation performance. Examples of transparent electrode materials include oxides such as ITO and indium zinc oxide (IZO); and metal thin films. The light transmittance of the upper electrode is preferably 80% or more except for the loss due to partial reflection at the optical interface, considering the power generation efficiency of the solar cell element.

  The materials for the lower electrode and the upper electrode may be used alone or in combination of two or more in any combination and ratio.

  There is no restriction | limiting in the formation method of a lower electrode and an upper electrode. For example, it can be formed by a dry process such as vacuum deposition or sputtering. It can also be formed by a wet process using conductive ink or the like. As this conductive ink, for example, a conductive polymer, a metal particle dispersion, or the like can be used. Furthermore, two or more electrodes may be laminated, and characteristics (electric characteristics, wetting characteristics, etc.) due to surface treatment may be improved.

Hereinafter, an organic thin film solar cell element (hereinafter, also referred to as a solar cell element) having a monolithic structure in which organic thin film solar cells (hereinafter also referred to as solar cells) having a photoelectric conversion layer, an upper electrode, and a lower electrode are connected in series. Will be described with reference to FIG. Although the case where the photoelectric conversion layer is a pin junction type will be described as an example with reference to FIG. 1, known organic photoelectric conversion layers such as a bulk heterojunction type, a hetero pn junction type, and a Schottky type are also similar. It can be manufactured by the method.

(substrate)
A solar cell element is usually manufactured by forming a plurality of solar cells on a substrate. As the substrate 1, a known substrate can be used. Specifically, for example, glass having a thickness of about 0.05 to 1 mm, metal foil, polyethylene naphthalate, polyethylene terephthalate, poly (meth) acrylic resin film, or the like, a heat resistant polymer. A film etc. are mentioned. When the light receiving surface of the solar cell module is on the substrate 1 side, it is preferable to use a transparent substrate. When the light receiving surface is on the upper electrode 8 side, the substrate 1 may be transparent or opaque. (A) As shown in the figure, a lower electrode 2 having an open groove 11 is formed on a substrate 1. The electrode may be formed by either a dry method or a wet method. Examples of the dry method include known methods such as sputtering, vapor deposition, and CVD. Examples of the wet method include screen printing and die coating. The width of the first groove 11 is preferably about 50 to 1000 μm, particularly about 100 to 500 μm.

  Next, a p layer 3 is formed on the lower electrode 2 as shown in FIG. When the p layer 3 is formed on the entire surface of the lower electrode 2, the first groove 11 is filled with the material of the p layer 3. When the p layer 3 is formed with a pattern on the lower electrode 2, the first groove 11 may not be filled with the material of the p layer 3.

  Next, as shown in (c), an i layer 4 and an n layer 5 are sequentially formed on the lower electrode 2 and the p layer 3. Next, as shown in (d), the i layer 4 and the n layer 5 formed on the p layer 3 are separated by several 10 to 100 μm in the vicinity so as not to overlap the first groove 11. A second groove 12 reaching the electrode 2 is formed by laser scribing. The width of the second groove is preferably about 50 to 1000 μm, particularly about 100 to 500 μm. The wavelength of the laser for forming the second open groove 12 is 200 to 1200 nm, preferably about 250 to 900 nm, particularly about 250 to 600 nm. Thereby, the p layer 3, the i layer 4, and the n layer 5 are separated into strips.

  Next, the upper electrode 6 is formed as shown in FIG. The second open groove 12 is filled with the material of the upper electrode 6. Since the second groove 12 is for connecting the upper electrode of the unit cell to the lower electrode 2 on the light receiving surface of the adjacent unit cell, it must reach the lower electrode 2.

  Thereafter, as shown in FIG. 5F, the upper electrode 6, the n layer 5, the i layer 4 and the p layer 3 are laser-scribed to form a third open groove 13 and divided into unit cells. Since the open groove 13 divides the upper electrode 6 of the adjacent unit cell, it may stop in the middle of the i layer 4 without penetrating the i layer 4, and further penetrate the p layer 3 from the i layer 4 to the lower part. It may enter the electrode 2. The wavelength of the laser forming the third groove 13 is 200 to 1200 nm, and preferably 250 to 900 nm, particularly about 250 to 600 nm. Since the upper electrode 6 of each unit cell is electrically connected to the lower electrode 2 of the adjacent unit cell by the material of the upper electrode 6 filling the open groove 12, a solar cell in which the unit cells are connected in series is obtained. .

  The material constituting the photoelectric conversion layer (in this embodiment, the p layer 3, the i layer 4, and the n layer 5) has a good absorption of light having a wavelength of 200 to 1200 nm, particularly 250 to 900 nm, and particularly 250 to 600 nm. The conversion layer is efficiently cut (scribed). The material constituting the upper electrode 6 may or may not absorb light having this wavelength. Even when the constituent material of the upper electrode 6 does not absorb light of this wavelength, when the underlying photoelectric conversion layer is removed by laser scribing, the upper electrode constituent material above the upper electrode 6 is removed together. 3 open grooves 13 are formed. Since the constituent material of the upper electrode 6 is not limited to the light absorbing material, options for the constituent material of the upper electrode are expanded.

<Collector>
In order to take out an electric current from a solar cell element, an electrode and a current collector are connected. In the present invention, the current collector is connected to the electrode via a conductive adhesive. Usually, the current collector and the electrode are connected at a place where the photoelectric conversion layer is not laminated. This is because if a physical action is applied to the photoelectric conversion layer during the connection, the photovoltaic cell may lose its electromotive ability.

For example, as shown in FIG. 2, a portion that is laminated with the photoelectric conversion layer 7 and a portion that is not laminated with the photoelectric conversion layer 7 are provided on the lower electrode 2 of the solar battery cell, and a portion that is laminated with the photoelectric conversion layer 7 on the upper electrode 6 A portion not laminated with the photoelectric conversion layer 7 is provided. And in the part which is not laminated | stacked with the photoelectric converting layer of each of the lower electrode 2 and the upper electrode 6 (both ends of FIG. 2), a collector wire is connected via the contact bonding layer 9, and two collector wires are made into a photovoltaic cell. Connecting.
In FIG. 2, at both ends of the solar battery cell, for example, a conductive material is laminated between the lower electrode and the current collector, or a material that does not affect current collection is laminated under the upper electrode. You may make it easy to install the current collector by flattening the upper and lower surfaces of the cell.

  Generally, in a solar cell module, electricity is taken out by connecting the current collector to the upper electrode and lower electrode of the solar cell element. However, even if the current collector is connected to only a plurality of upper electrodes, It can be taken out. This is because electricity flows through the photoelectric conversion layer between the upper electrode and the lower electrode of the solar battery cells forming the solar battery element, and the cells are connected in series, so the upper electrodes are connected to each other. This is because even electricity can be taken out.

Moreover, the photovoltaic cell which has the upper electrode connected with the current collection line may be short-circuited by the connection with a current collection line, and does not need to be short-circuited. In the case where the solar cell is short-circuited, electricity can be reliably flowed, so that stable electricity can be taken out. In order to ensure such a short circuit, for example, the current collector may be brought into contact with the other electrode by controlling the surface roughness of the current collector.
On the other hand, when not short-circuited, even a solar battery cell having an upper electrode to which the current collector is connected can generate power, and the power generation amount per area of the solar battery module can be increased.

As a material for the current collector, metals, alloys, and the like are often used, and among them, it is preferable to use copper, aluminum, silver, gold, nickel, or the like having a low resistivity. Among these, copper and aluminum are particularly preferable because they are inexpensive. In order to prevent rust, the current collector may be plated with tin, silver or the like, the surface may be coated with resin, or a film may be laminated. As the shape of the current collecting wire, there are a rectangular wire, foil, flat plate, and wire shape, but for reasons such as securing a bonding area, it is preferable to use a flat wire, foil, or flat plate shape.
In the present invention, the “foil” refers to one having a thickness of less than 100 μm, and the “plate” refers to a thickness of 100 μm or more. Further, the “flat wire” refers to a wire whose cross section is rolled to make the cross section into a quadrangle.

The current collector is not particularly limited as long as it has conductivity, but preferably has a lower resistance value than the upper electrode and lower electrode to be connected. In particular, by increasing the thickness of the upper electrode and lower electrode, resistance is increased. It is preferable to reduce the value. The thickness of the current collector is preferably 5 μm or more, more preferably 10 μm or more. Moreover, it is preferable that it is 2 mm or less, More preferably, it is 1 mm or less, More preferably, it is 300 micrometers or less, Most preferably, it is 200 micrometers or less. If the thickness is thinner than the above range, the resistance value of the current collector increases, and the generated power may not be efficiently taken out to the outside. Further, if the thickness is larger than the above range, there is a risk that the solar cell module will increase in weight and the flexibility will decrease, the surface of the module will easily become uneven, and the production cost will increase. is there.

  The width of the current collector is preferably 0.5 mm or more, more preferably 1 mm or more, and particularly preferably 2 mm or more. Moreover, it is preferable that the width | variety of a current collection line is 50 mm or less, More preferably, it is 20 mm or less, Most preferably, it is 10 mm or less. If the width of the current collection line is narrower than the above range, the resistance value of the current collection line will increase, and the generated power may not be taken out efficiently. In addition, the mechanical strength of the current collector decreases, which may cause breakage and the like. Moreover, when the width | variety of a current collection line is wider than the said range, the aperture ratio in the whole module will reduce, and there exists a possibility of leading to the fall of the power generation amount of a module.

In addition, the shape of the current collector line can be embossed. The embossed shape means a shape formed by embossing some uneven shape. By forming the current collector in an embossed shape, even if an adhesive layer is used, a portion of the embossed unevenness can be in direct contact with or very close to the electrode, so that conductivity is increased.
The embossing depth is usually 5 to 100 μm, and preferably 10 to 50 μm. The embossing depth means the height of the convex portion formed by embossing, and is specifically a value obtained by subtracting the thickness of the current collector from the thickness including the convex portion. Such an embossing depth is preferable because the embossed convex portion can directly contact the electrode.

<Adhesive layer>
The present invention is characterized in that the current collector is connected to the electrode via a conductive adhesive (adhesive layer 9 in FIG. 2). Another layer may be laminated as long as the effect of the present invention is not impaired. By using a conductive adhesive, since it is not necessary to apply heat during processing, deterioration of the photoelectric conversion layer due to heat can be prevented. In addition, unlike adhesives such as thermosetting adhesives and photo-curable adhesives, conductive adhesives hardly cure or shrink, so that no stress is generated during bonding or is extremely small. Therefore, the use of the conductive pressure-sensitive adhesive can prevent damage to the photoelectric conversion layer due to stress generated during bonding.

Note that the term “conductive” means that at least electrical connection is possible, but the volume resistivity at room temperature (25 ° C.) is usually 10 Ωcm or less and 10 ⁻⁶ Ωcm or more.

  The adhesive is a substance that has adhesiveness at room temperature and adheres to the adherend at a light pressure as defined in JISK6800, for example. Pressure sensitive adhesives) are also included. It means a material that is bonded by pressure and does not involve hardening of the bonded portion. Those which cause an adhesive action with curing are not included in the pressure-sensitive adhesive of the present invention.

  As the conductive adhesive, for example, a material in which conductive particles are dispersed in an acrylic, rubber, silicone, or urethane resin can be used. Among these, those using an acrylic resin are preferable because they have high weather resistance and heat resistance, and there are few restrictions on the adherend.

  As the acrylic resin, for example, one obtained by solution polymerization of one or more (meth) acrylic acid esters in an organic solvent can be used. In order to exert a cohesive force, isocyanate, butylated melamine or the like may be used in combination as a crosslinking agent. Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, and the like.

Examples of rubbers include natural rubber, polybutadiene rubber, styrene-butadiene rubber, polyisobutylene rubber, isoprene rubber, and butyl rubber.
In the silicone system, any polymer containing a polysiloxane skeleton having a siloxane bond can be used, and various modified silicones such as vinyl silicone rubber, phenylmethyl silicone rubber, phenyl vinyl silicone rubber, epoxy-modified silicone and polyimide-modified silicone can be used. .

  As a weight average molecular weight of resin used for an electroconductive adhesive, it is 50,000-2 million normally, and 100,000-1 million are preferable from the balance of adhesiveness and durability. The weight average molecular weight can be measured by gel permeation chromatography (GPC) using polystyrene as a standard substance. Moreover, the glass transition temperature (Tg) measured by DSC measurement is -80 degreeC-100 degreeC normally, and -60-50 degreeC is preferable from the balance of adhesiveness and durability.

  Conductive particles include metal particles such as gold, nickel, copper, silver, platinum, solder, palladium, aluminum, or alloys thereof, carbon-based particles such as carbon black, carbon tube, and carbon fiber, and gold-plated nickel particles. And metal coated resin particles such as gold / nickel plated resin particles, copper plated resin particles, nickel plated resin particles, etc. From the viewpoint of conductivity, metal particles, composite metal particles, metal coated resins Particles are preferred. Such a conductive particle is used in the above-mentioned resin, usually containing 0.01 to 50% by volume, preferably 0.1 to 20% by volume. If the content of the conductive particles is less than 0.1% by volume, the connection stability due to the conductive particles may not be sufficiently exerted, and the conductivity may be lowered, and the content of the conductive particles is 20 When it exceeds volume%, the moldability of the resin layer is lowered, and the adhesive strength may be lowered.

  The shape of the conductive particles is not particularly limited, and examples thereof include a spherical shape, a needle shape, a fiber shape, a flake shape, a spike shape, and a coil shape. Although it does not specifically limit as a magnitude | size of an electroconductive particle, For example, a particle size is 1-50 micrometers, Preferably it is 2-20 micrometers. The particle size is a value measured by the BET method.

  When the conductivity of the conductive adhesive is low, a part of the electrode and the current collector may be fixed with the conductive adhesive, and the electrode and the current collector may be installed in direct contact with the remaining part.

  The conductive pressure-sensitive adhesive used in the present invention can contain a filler such as silica and mica, a pigment, an antistatic agent, and the like, if necessary. Coloring agents, preservatives, polyisocyanate crosslinking agents, silane coupling agents, and the like can also be blended.

<Encapsulant>
In the present invention, the solar cell module is manufactured by connecting the solar cell element and the collector wire, but at least the solar cell element is preferably sealed. The solar cell element is sealed in order to reinforce the solar cell element and increase impact resistance.
The sealing material used for sealing preferably has high strength from the viewpoint of maintaining the strength of the solar cell module. The specific strength is related to the strength of the layers other than the sealing material, and it is difficult to define in general. However, the entire solar cell module has good bending workability so that peeling of the bent portion does not occur. It is desirable to have sufficient strength.

  Further, when the sealing material is used on the light receiving surface side of the solar battery cell, it is preferable to transmit visible light from the viewpoint of preventing light absorption. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 75% or more, preferably 80% or more, more preferably 85% or more, further preferably 90% or more, and particularly preferably 95% or more. Particularly preferably, it is 97% or more. This is to convert more sunlight into electrical energy.

On the other hand, when a sealing material is used on the side opposite to the light receiving surface of the solar cell element, it is not always necessary to transmit visible light and may be opaque.
Furthermore, since the solar cell module is often heated by receiving light, it is preferable that the sealing material also has heat resistance. From this viewpoint, the melting point of the constituent material of the sealing material is usually 100 ° C. or higher, preferably 120 ° C. or higher, more preferably 130 ° C. or higher, and usually 350 ° C. or lower, preferably 320 ° C. or lower, more preferably It is 300 degrees C or less. By increasing the melting point, it is possible to prevent the sealing material from melting and deteriorating when the solar cell module is used.

  The thickness of the sealing material is not particularly defined, but is usually 5 μm or more, preferably 10 μm or more, more preferably 30 μm or more, and usually 1000 μm or less, preferably 800 μm or less, more preferably 600 μm or less. Increasing the thickness tends to increase the strength of the entire solar cell module, and decreasing the thickness tends to increase flexibility and improve the visible light transmittance. For this reason, it is desirable to set it as the said range as a range which has both advantages.

As a material which comprises a sealing material, what used the ethylene-vinyl acetate copolymer (EVA) resin composition for the film (EVA film) etc. can be used, for example.
However, since the EVA resin cross-linking process requires a relatively long time, it may cause a reduction in the production speed and production efficiency of the solar cell module. In addition, when used for a long time, the decomposition gas (acetic acid gas) of the EVA resin composition or the vinyl acetate group of the EVA resin itself may adversely affect the solar cell element and reduce the power generation efficiency. Therefore, as the sealing material, a copolymer film made of a propylene / ethylene / α-olefin copolymer can be used in addition to the EVA film.

Note that the sealing material may be formed of one kind of material or may be formed of two or more kinds of materials. Moreover, although the sealing material may be formed with the single layer film, the laminated | multilayer film provided with the film of two or more layers may be sufficient as it.
The sealing material is usually provided so as to sandwich the solar cell element.
In addition, the sealing material may be provided with functions such as ultraviolet blocking, heat blocking, conductivity, antireflection, antiglare, light diffusion, light scattering, wavelength conversion, and gas barrier properties. In particular, in the case of a solar cell, it is vulnerable to water and oxygen and is exposed to strong ultraviolet rays from sunlight, and therefore preferably has a gas barrier property and an ultraviolet blocking function.
As a method of imparting such a function, a layer having a function may be laminated on the sealing material by coating film formation or the like, or a material that exhibits the function is dissolved and dispersed in the sealing material. You may make it contain.

Examples of the gas barrier property include those satisfying the following water vapor permeability and oxygen permeability.
As the water vapor transmission rate, the water vapor transmission rate Pd at a sealing material thickness of 100 μm is usually 10 ⁻¹ g / m ² / day or less, preferably 10 ⁻² g / m ² / day in a 40 ° C. and 90% RH environment. Hereinafter, it is more preferably 10 ⁻³ g / m ² / day or less, and further preferably 10 ⁻⁴ g / m ² / day or less. The water vapor transmission rate is measured in an environment of 40 ° C. and 90% RH by a measurement using an apparatus equipped with a humidity sensor, an infrared sensor, and a gas chromatograph according to JIS K7129, or by a cup method (JIS Z0208).

As the oxygen permeability, for example, generally, the oxygen permeability per day of a unit area (1 m ² ) at a thickness of 100 μm in a 25 ° C. environment is usually 1 cc / m ² / day / atm or less. , 1 is preferably × ¹⁰ -1 or less ^{cc / m 2 / day / atm} , more preferably not more than ^{1 × 10 -2 cc / m 2} / day / atm, 1 × 10 -3 cc / m ² / day / atm or less is more preferable, 1 × 10 ⁻⁴ cc / m ² / day / atm or less is particularly preferable, and 1 × 10 ⁻⁵ cc / m ² / day / atm or less. It is particularly preferred. There is an advantage that the deterioration due to the oxidation of the element can be suppressed as the oxygen does not permeate. The oxygen permeability can be measured with an apparatus based on a differential pressure method according to JIS K7126A, or an apparatus equipped with an infrared sensor and a gas chromatograph based on an isobaric method according to JIS K7126B.

The sealing step of sealing the solar cell element with the sealing material may be performed after the step of connecting the upper electrode and the current collector, or may be performed before the step of connecting the upper electrode and the current collector.
When the solar cell module is further sealed after the step of connecting the upper electrode and the current collector, the entire solar cell module including the current collector is sealed, and then the solar cell module sealing material is sealed. Of these, it is also possible to form a slit at a location where a current collector line from which electricity is to be taken is present, and to take out the current collector line from the slit.
In this case, the number of connection points of the collector line to the upper electrode is arbitrary as long as it is one or more, and the collector line may be connected to a position where a desired potential can be taken out.

  If there is a step of sealing the solar cell module before the step of connecting the upper electrode and the current collector, a slit is formed at the position where the current collector is connected to the sealing material after sealing. Thus, the upper electrode is exposed on the surface of the solar cell module. And what is necessary is just to connect the upper electrode and collector wire of the position of a slit. Moreover, by providing a slit at a specific position in advance in the sealing material before sealing, the labor of forming the slit after sealing can be saved. By providing the slit in advance in this way, it is possible to eliminate the possibility of damage to the solar battery cell that occurs when the slit is formed after sealing.

  In the solar cell module of the present invention, a weatherproof protective sheet can be further provided on the outermost surface after sealing. The weather-resistant protective sheet is a sheet and film that protects the solar cell module from a device installation environment such as temperature change, humidity change, light, and wind and rain. By covering the device surface with a weather-resistant protective sheet, there is an advantage that a solar cell module constituent material, particularly a solar cell element, is protected and high power generation capability can be obtained without deterioration.

Since the weatherproof protective sheet is located on the outermost layer of the solar cell element, it has suitable performance as a surface covering material for solar cells, such as weather resistance, heat resistance, transparency, water repellency, stain resistance, mechanical strength, etc. It is preferable to have such a property that it is provided and is maintained for a long period of time in outdoor exposure.
In addition, when the weatherproof protective sheet is used on the light receiving surface side of the solar battery cell, it is preferable to transmit visible light from the viewpoint of preventing light absorption. For example, the transmittance of visible light (wavelength 360 to 830 nm) is usually 75% or more, preferably 80% or more, more preferably 85% or more, further preferably 90% or more, and particularly preferably 95% or more. Particularly preferably, it is 97% or more. This is to convert more sunlight into electrical energy.

On the other hand, when using a weatherproof protective sheet on the side opposite to the light receiving surface of the solar cell element, it is not always necessary to transmit visible light, and may be opaque.
Furthermore, since the solar cell element is often heated by receiving light, it is preferable that the weatherproof protective sheet also has heat resistance. From this viewpoint, the melting point of the constituent material of the weatherproof protective sheet is usually 100 ° C or higher, preferably 120 ° C or higher, more preferably 130 ° C or higher, and usually 350 ° C or lower, preferably 320 ° C or lower, more preferably. Is 300 ° C. or lower. By increasing the melting point, it is possible to reduce the possibility that the weatherproof protective sheet will melt and deteriorate when the solar cell element is used.

The material which comprises a weather-resistant protective sheet is arbitrary as long as it can protect a solar cell module. Examples of the material include polyethylene resin, polypropylene resin, cyclic polyolefin resin, AS (acrylonitrile-styrene) resin, ABS (acrylonitrile-butadiene-styrene) resin, polyvinyl chloride resin, fluorine resin, polyethylene terephthalate, polyethylene Examples thereof include polyester resins such as naphthalate, phenol resins, polyacrylic resins, polyamide resins such as various nylons, polyimide resins, polyamide-imide resins, polyurethane resins, cellulose resins, silicone resins, and polycarbonate resins.

  Among them, fluorine resin is preferable, and specific examples thereof include polytetrafluoroethylene (PTFE), 4-fluoroethylene-perchloroalkoxy copolymer (PFA), 4-fluoroethylene-6-fluoride. Propylene copolymer (FEP), 2-ethylene-4-fluoroethylene copolymer (ETFE), poly-3-fluoroethylene chloride (PCTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), etc. Can be mentioned.

In addition, the weather-resistant protective sheet may be formed of one type of material or may be formed of two or more types of materials. Moreover, the weather-resistant protective sheet may be formed of a single layer film, but may be a laminated film including two or more layers.
The thickness of the weatherproof protective sheet is not particularly defined, but is usually 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and usually 200 μm or less, preferably 180 μm or less, more preferably 150 μm or less. Increasing the thickness tends to increase mechanical strength, and decreasing the thickness tends to increase flexibility. For this reason, it is desirable to set it as the said range as a range which has both advantages.

Moreover, you may perform surface treatments, such as a corona treatment and a plasma treatment, in order to improve the adhesiveness with another film to a weather-resistant protective sheet.
The weatherproof protective sheet is preferably provided on the outer side as much as possible in the solar cell module. This is because more device components can be protected.
In addition, UV protection, heat ray blocking, antifouling properties, hydrophilicity, hydrophobicity, antifogging properties, abrasion resistance, conductivity, antireflection, antiglare properties, light diffusion, light scattering, wavelength conversion, Functions such as gas barrier properties may be imparted. In particular, in the case of a solar cell, it is preferable to have an ultraviolet blocking function because it is exposed to strong ultraviolet rays from sunlight.

  As a method for imparting such a function, a layer having a function may be laminated on a weather-resistant protective sheet by coating film formation or the like, or a weather-resistant protection is achieved by dissolving or dispersing a material exhibiting the function. You may make it contain in a sheet | seat.

  The manufacturing method of the solar cell module of the present invention is not particularly limited, and a known method may be applied. Specifically, necessary layers can be laminated, and a heat laminating method using a vacuum laminator or a roll laminator can be used.

In the case of thermal lamination, it is preferably performed under vacuum conditions, and the degree of vacuum is usually 10 Pa or more, preferably 20 Pa or more, more preferably 30 Pa or more. On the other hand, the upper limit is usually 150 Pa or less, preferably 120 Pa or less, more preferably 100 Pa or less. By setting it as the said range, since generation | occurrence | production of a bubble can be suppressed in each layer in a module, and productivity improves, it is preferable.
The vacuum time is usually 1 minute or longer, preferably 2 minutes or longer, more preferably 3 minutes or longer. On the other hand, the upper limit is usually 20 minutes or less, preferably 18 minutes or less, more preferably 15 minutes or less. Setting the vacuum time in the above range is preferable because the appearance of the solar cell module after heat lamination becomes good and generation of bubbles due to heat lamination conditions can be suppressed in each layer in the module.

The pressurizing condition of the thermal laminate is usually a pressure of 50 kPa or more, preferably 70 kPa or more, more preferably 90 kPa or more. On the other hand, the upper limit value is preferably 101 kPa or less. By setting it as the pressurization conditions of the said range, since moderate adhesiveness can be acquired, without damaging a solar cell module, it is preferable also from a durable viewpoint.
The holding time of the pressure is usually 1 minute or longer, preferably 3 minutes or longer, more preferably 5 minutes or longer. On the other hand, the upper limit is usually 50 minutes or less, preferably 40 minutes or less, more preferably 30 minutes or less. By setting it as the said holding time, since the gelling rate of a sealing material can be made appropriate, sufficient adhesive strength can be obtained.

The temperature condition of the thermal laminate is usually 115 ° C. or higher, preferably 120 ° C. or higher, more preferably 125 ° C. or higher. On the other hand, the upper limit is usually 180 ° C. or lower, preferably 165 ° C. or lower, more preferably 155 ° C. or lower. By setting the temperature range, sufficient adhesive strength can be obtained.
The temperature holding time is usually 1 minute or longer, preferably 3 minutes or longer, more preferably 5 minutes or longer. On the other hand, the upper limit is 50 minutes or less, preferably 40 minutes or less, more preferably 30 minutes or less. By setting it as the said holding time, since crosslinking of a sealing material is performed moderately, durability performance improves and it can have moderate softness | flexibility, and is preferable.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, it cannot be overemphasized that this invention is not limited only to a following example.

<Example 1>
Thickness 180μm, width 5mm on solar cell (stacked with PEN, zinc oxide, P3HT: C60 bisindene adduct, PEDOT: PSS and using ITO / Ag / ITO, Ag respectively as upper electrode and lower electrode) The current collectors made by Hitachi Cable are connected with a conductive adhesive CN4490 made by Sumitomo 3M. The solar battery cell connected with the current collector is heat-pressed at 140 ° C. using a sealing material EVA and a laminator manufactured by NPC (vacuum degree 80 Pa, vacuum time 2 minutes, pressurization time 2 minutes, holding 16 minutes) ) To obtain the solar cell module 1. Appearance and photoelectric conversion efficiency are evaluated as shown in Table 1.

<Comparative Example 1>
In Example 1, the solar cell module 2 is obtained in the same manner except that the conductive adhesive is replaced with a thermosetting conductive adhesive CP-300 manufactured by Hitachi Chemical Co., Ltd. and heated and connected at 120 ° C. for 20 minutes. Appearance and photoelectric conversion efficiency are evaluated as shown in Table 1.

<Comparative example 2>
The solar cell module 2 is obtained in the same manner as in Example 1 except that the conductive adhesive is replaced with solder. Appearance and photoelectric conversion efficiency are evaluated as shown in Table 1.

<Comparative Example 3>
In Example 1, the solar cell module 2 is obtained in the same manner except that the conductive adhesive is replaced with silver paste. Appearance and photoelectric conversion efficiency are evaluated as shown in Table 1.
As mentioned above, according to this invention, it turns out that the organic thin-film solar cell module with little deterioration of a module at the time of solar cell module manufacture is obtained.

In the appearance evaluation, a case where deformation, burnt, wrinkle, floating, and / or warping of the module is observed is evaluated as x, and a case where the module is not observed is evaluated as good.

1 translucent substrate 2 lower electrode 3 p layer 4 i layer 5 n layer 6 upper electrode 7 photoelectric conversion layer 8 current collector 9 adhesive layer 11 first groove 12 second groove 13 third groove

Claims (2)

A solar cell element in which at least a photoelectric conversion layer, a substrate that supports the photoelectric conversion layer, and at least a pair of electrodes that are connected to the photoelectric conversion layer on a light-receiving surface side and a non-light-receiving surface side of the photoelectric conversion layer;
In a solar cell module comprising a solar cell having at least a pair of current collectors connected to the electrodes,
The said collector wire is connected to the said electrode through the electroconductive adhesive, The solar cell module characterized by the above-mentioned.   The solar cell module according to claim 1, wherein the current collector has a thickness of 200 μm or less.