JP2008147230A - Substrate for solar cell, solar cell module and solar cell device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a substrate for solar cell which has a transparent electrode with a low resistance and a micro-texture structure to the extent of demonstrating grating effect, and to provide a solar cell module with high photoelectric conversion efficiency by using the same, as well as to provide a solar cell device. <P>SOLUTION: A diffraction grating layer, made mainly of translucent insulating resin, is provided between a transparent insulating substrate and a translucent electrode, and as the translucent insulating resin, a resin made mainly of ionizing radiation curing resin, thermocuring resin or cast resin has a glass transition point (Tg) of 240°C or higher. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a solar cell substrate installed outside a solar cell unit (incident light side), and more specifically, has a texture structure for effectively using light incident on a solar cell module for power generation. It relates to a solar cell substrate.

The “texture” described in this specification is an industry term for “fine irregularities” whose contour can be confirmed with an electron microscope.
In addition, “microcrystalline” described in the present specification includes a case where it partially contains amorphous.
In addition, the “main component” described in the specification of the present application refers to a main component among the constituent components, and specifically refers to a component constituting 50% by mass or more.

Solar-powered solar cells use fossil fuels that are feared to run out of resources (crude oil availability: about 30 years, natural gas availability: about 40 years, uranium availability: about 45 years) It is attracting attention as a power generation system that does not have to be.

As the structure of the solar cell module, a transparent electrode made of SnO ₂ , ITO or ZnO, a solar cell unit layer having a photoelectric conversion function, a back surface made of Ag, Al or the like on a transparent insulating substrate made of glass or plastic A structure in which electrode layers are stacked in this order is well known.

As a material for the solar cell unit, attention has been focused on amorphous silicon that can be formed at a relatively low temperature of about 100 to 200 ° C.

However, a solar cell unit made of amorphous silicon has a problem that the photoelectric conversion efficiency is low.

As an attempt to increase the photoelectric conversion efficiency, a texture structure is formed on the surface of the transparent electrode by an etching method, and light to be dissipated from the solar cell unit is enclosed in the solar cell unit by the texture structure. A method has been proposed in which incident light to the unit is diffusely reflected by a texture structure to increase the optical path length of the incident light in the solar cell unit. (For example, see Patent Document 1)

Further, as an attempt to increase the photoelectric conversion efficiency, a method of forming a texture structure on the surface of a transparent insulating substrate by a sand blast method has been proposed. (For example, see Patent Document 2)

JP-A-61-288473 Japanese Patent Laid-Open No. 1-219043

However, when a texture structure is formed on the surface of the transparent electrode by an etching method, a crack occurs in the transparent electrode, and as a result, the resistance value of the transparent electrode becomes high.

Further, even if a texture structure is formed on the surface of the transparent insulating substrate by the sand blast method, a fine texture structure that can exhibit a diffraction effect cannot be obtained.

An object of the present invention is to provide a solar cell substrate having a low texture of a transparent electrode and a fine texture structure capable of exhibiting a diffraction grating effect, a solar cell module and a solar cell using the same It is to provide a battery device.

The invention according to claim 1 is a solar cell substrate comprising a transparent insulating substrate and a diffraction grating layer formed on the transparent insulating substrate and having a textured structure on the surface,
The said diffraction grating layer is a board | substrate for solar cells characterized by having translucent insulating resin as a main component.

The transparent insulating substrate serves to prevent moisture from entering the solar cell unit, to block ultraviolet rays, and to protect the solar cell module from external forces.

The diffraction grating layer diffuses and reflects the incident light to the solar cell unit, increases the optical path length of the incident light in the solar cell unit, and the light to be dissipated from the solar cell unit in the texture structure. It plays a role of containment in the battery unit.

The translucent insulating resin is a material for forming a fine texture structure.

According to a second aspect of the present invention, the translucent insulating resin has a glass transition point (Tg) of 240 ° C. or higher, and an ionizing radiation curable resin, a thermosetting resin, or a cast resin as a main component. It is a board | substrate for solar cells of Claim 1 characterized by these.

An ionizing radiation curable resin, a thermosetting resin, or a cast resin has a role of facilitating fine processing of a texture layer of several tens of nm level.

When the glass transition point (Tg) of the ionizing radiation curable resin, thermosetting resin or cast resin is in the range of 240 ° C. or higher, the glass of the resin during the high temperature (about 100 to 200 ° C.) treatment in the solar cell unit forming step. No metastasis occurs.

The invention according to claim 3 is the solar cell substrate according to claim 1, wherein the transparent insulating substrate is chemically tempered glass or physical tempered glass. It is.

Chemically tempered glass or physically tempered glass plays a role as a protective material for a small and light solar cell module as compared with conventional soda-lime glass.

The invention described in claim 4 is characterized in that the transparent insulating substrate is a single plastic film or a laminated plastic film having a glass transition point (Tg) of 240 ° C. or higher. 2. The solar cell substrate according to 2.

The plastic film plays a role of facilitating mass production by a roll-to-roll method while serving as a solar cell module protective material.

When the glass transition point (Tg) of the plastic film is in the range of 240 ° C. or higher, the glass transition of the plastic film does not occur during the high temperature (about 100 to 200 ° C.) treatment in the solar cell unit forming step.

In the invention according to claim 5, the diffraction grating layer has a honeycomb structure, and the length of one side (L in FIG. 1) constituting the honeycomb structure is 100 to 10,000 nm,
The cell partition wall thickness (W in FIG. 1) is 10 to 300 nm,
The ratio of the cell partition wall height (H in FIG. 1) to the cell partition wall thickness (W in FIG. 1) is in the range of 1/8 to 5/4. It is a substrate for solar cells of any one.

When it is within this range, the photoelectric conversion efficiency of sunlight near 500 nm at which the energy intensity in the total wavelength region of sunlight is maximized is maximized.

According to a sixth aspect of the present invention, the diffraction grating layer has a structure in which convex portions and concave portions are periodically arranged two-dimensionally, and the shape of the convex portion viewed from the thickness direction of the diffraction grating is circular. The solar cell substrate according to any one of claims 1 to 4, wherein the substrate is a solar cell substrate.

When the diffraction grating layer is formed in this way, the photoelectric conversion efficiency of sunlight around 500 nm at which the energy intensity in the entire wavelength region of sunlight is maximized is maximized.

The invention according to claim 7 is a solar cell substrate, wherein a transparent electrode is formed on the diffraction grating layer of the solar cell substrate according to any one of claims 1 to 6. It is.

The transparent electrode serves as an electrode for the solar cell module.

The invention according to claim 8 is a solar cell unit formed on the transparent electrode,
A back electrode formed on the solar cell unit;
It is a solar cell module which has.

The solar cell unit plays a role of converting light incident on the solar cell module into electricity.

The back electrode serves as an electrode for the solar cell module.

The invention according to claim 9 is a solar cell device characterized in that the solar cell module is surrounded by a light reflecting material having a light incident surface of the solar cell module as an opening.

The light reflecting material plays a role of reflecting light leaking from the solar cell module on the surface of the light reflecting material and re-entering the solar cell module.

The invention according to claim 1 is a solar cell substrate comprising a transparent insulating substrate and a diffraction grating layer formed on the transparent insulating substrate and having a textured structure on the surface,
The said diffraction grating layer is a board | substrate for solar cells characterized by having translucent insulating resin as a main component.

By providing a diffraction grating layer mainly composed of a translucent insulating resin between the transparent insulating base material and the transparent electrode, the transparent electrode has a low resistance value and a fine texture capable of exhibiting a diffraction effect. A solar cell substrate having a structure can be obtained.

According to a second aspect of the present invention, the translucent insulating resin has a glass transition point (Tg) of 240 ° C. or higher, and an ionizing radiation curable resin, a thermosetting resin, or a cast resin as a main component. It is a board | substrate for solar cells of Claim 1 characterized by these.

By using an ionizing radiation curable resin, a thermosetting resin or a cast resin as the material of the texture layer, the texture layer can be made finer, and thus a small and lightweight solar cell substrate can be obtained. .

The invention according to claim 3 is the solar cell substrate according to claim 1, wherein the transparent insulating substrate is chemically tempered glass or physical tempered glass. It is.

By making the transparent base material chemically tempered glass or physical tempered glass, the solar cell module can be reduced in size and weight.

The invention described in claim 4 is characterized in that the transparent insulating substrate is a single plastic film or a laminated plastic film having a glass transition point (Tg) of 240 ° C. or higher. 2. The solar cell substrate according to 2.

By doing so, the solar cell module can be reduced in size and weight, and the roll-to-roll method with excellent productivity can be used. As a result, the solar cell module can be reduced in size and weight without increasing the manufacturing cost. A battery substrate can be obtained.

In the invention according to claim 5, the diffraction grating layer has a honeycomb structure, and the length of one side (L in FIG. 1) constituting the honeycomb structure is 100 to 10,000 nm,
The cell partition wall thickness (W in FIG. 1) is 10 to 300 nm,
The ratio of the cell partition wall height (H in FIG. 1) to the cell partition wall thickness (W in FIG. 1) is in the range of 1/8 to 5/4. It is a substrate for solar cells of any one.

By making the diffraction grating layer in this way, a solar cell module with good photoelectric conversion efficiency can be obtained.

According to a sixth aspect of the present invention, the diffraction grating layer has a structure in which convex portions and concave portions are periodically arranged two-dimensionally, and the shape of the convex portion viewed from the thickness direction of the diffraction grating is circular. The solar cell substrate according to any one of claims 1 to 4, wherein the substrate is a solar cell substrate.

By making the diffraction grating layer in this way, a solar cell module with good photoelectric conversion efficiency can be obtained.

The invention according to claim 7 is a solar cell substrate, wherein a transparent electrode is formed on the diffraction grating layer of the solar cell substrate according to any one of claims 1 to 5. It is.

By forming a transparent electrode, it can be used as a component of a solar cell module.

The invention according to claim 8 is a solar cell unit formed on the transparent electrode,
A back electrode formed on the solar cell unit;
It is a solar cell module which has.

By forming the solar cell unit and the back electrode in this order on the transparent electrode of the solar cell substrate, a solar cell with high photoelectric conversion efficiency can be obtained.

The invention according to claim 9 is a solar cell device characterized in that the solar cell module is surrounded by a light reflecting material having a light incident surface of the solar cell module as an opening.

By surrounding the solar cell module with the light reflecting material, a solar cell module with high photoelectric conversion efficiency can be obtained.

Hereinafter, based on FIG. 2, FIG. 3, FIG. 4, and FIG. 5 of the present invention, a method for manufacturing a solar cell substrate, a solar cell module, and a solar cell device of the present invention will be described.

(Preparation of diffraction grating shape transfer stamper)
First, a photoresist 200 is applied on the stamper substrate 100. (See Fig. 3 (a))

The material that can be used as the stamper substrate 100 may be either opaque or transparent as long as it has dimensional stability and low thermal expansibility. For example, aluminum, glass, crystal, copper, brass, Steel, magnesium, cadmium, silver, gold, polyester film, polyamide film, and polycarbonate, or a composite material composed of the above materials can be used, and it is chemically inert and inexpensive during the optical component manufacturing process. From the viewpoint, glass is preferable.

The material that can be used as the photoresist 200 is not particularly limited as long as it is a composition that forms a cross-linked or high-molecular-weight polymer by exposure to ionizing radiation and has reduced solubility in a solvent. From this point of view, a naphthoquinonediazide-novolak positive resist is preferred.

The material that can be used as the stamper substrate 100 may be either opaque or transparent as long as it has dimensional stability and low thermal expansibility. For example, aluminum, glass, crystal, copper, brass, Steel, magnesium, cadmium, silver, gold, polyester film, polyamide film, and polycarbonate, or composite materials composed of the above materials can be used. From the viewpoint of chemical inertness during the optical component manufacturing process, glass Is preferred.

The material that can be used as the photoresist 200 is not particularly limited as long as it is a composition that forms a cross-linked or high-molecular-weight polymer by exposure to ionizing radiation and has reduced solubility in a solvent. From this point of view, a naphthoquinonediazide-novolak positive resist is preferred.

In order to improve the adhesion between the naphthoquinonediazide-novolak positive resist (photoresist 200) and the glass plate (stamper substrate 100), the surface of the glass plate (stamper substrate 100) is vaporized with HMDS (hexamethyldisilazane). Processing may be performed.

As a method for applying the photoresist 200 onto the stamper substrate 100, a roll coating method, a curtain flow coating method, a screen printing method, a spray coater method, a spin coating method, or the like can be used. From the viewpoint that the thickness of the thin film can be made uniform, the spin coating method is preferable.

Next, the positive photoresist 200 is solubilized by exposing the photoresist 200 at the diffraction limit using actinic radiation and an optical system mask. (See Fig. 3 (b))

As the active light source, HeCd laser, excimer laser, low pressure mercury lamp, high pressure mercury lamp, ultra high pressure mercury lamp, arc lamp, xenon lamp, X-ray, electron beam, etc. can be used. When a positive resist is used, a HeCd laser is preferable from the viewpoint of resolution.

As an exposure method, a method using a reduced projection exposure apparatus or a mirror type projection exposure apparatus can be used in addition to a method of irradiating active rays after an optical mask is brought into close contact with the photoresist 200. From this point of view, a method of irradiating the active ray after the optical mask is brought into close contact with the photoresist 200 is preferable.

Next, the solubilized photoresist 200 ′ is removed (developed) using a developer. (See Fig. 3 (c))

As the developing solution, sodium silicate-based, sodium phosphate-based, or an alkaline solution such as a buffer solution or quaternary alkyl ammonium hydroxide can be used, and among them, a tetramethylammonium aqueous solution that hardly causes development fogging is preferable.

As the removal (development) method, a spray method or a dipping method can be used, but the spray method is preferable from the viewpoint of continuous productivity.

A surfactant may be added to the developer to improve development uniformity.
As the surfactant to be added, an anionic surfactant (for example, N-acylamino acid and its salt, alkylsulfocarboxylate, α-olefinsulfone, which has little development inhibitory effect and has good compatibility with a developer (alkaline solution)). Acid salt, polyoxyethylene alkyl ether acetate, N-acylmethyl taurate, alkyl sulfate polyoxyalkyl ether sulfate, alkyl sulfate polyoxyethylene alkyl ether phosphate, rosin acid soap, castor oil sulfate ester, lauryl Alcohol sulfate salts, alkylphenol phosphates, alkyl phosphates, alkyl allyl sulfonates, etc.) can be used.

Among the anionic surfactants, alkylsulfocarboxylates having a relatively large molecular weight and high permeability are preferable from the viewpoint of compatibility with a developer and stability.

Next, a conductive layer 300 is formed over the photoresist 200 ″. (See Fig. 3 (d))

Nickel or silver can be used as the material of the conductive layer 300, but nickel is preferable from the viewpoint of cost.

As a formation method, an electroless plating method and a sputtering method can be used. From the viewpoint of adhesion between the photoresist 200 ″ and the conductive layer 300, a sputtering method is preferable.

Next, the metal layer 400 is formed on the conductive layer 300 by electroforming using the conductive layer 300 as an electrode. (See Fig. 3 (e))

Nickel or copper can be used as the material of the metal layer 400, but nickel is preferable from the viewpoint of dimensional stability during the optical component manufacturing process.

Next, the stamper 500 is obtained by removing the stamper substrate 100 and the photoresist 200 ″. (See Fig. 3 (f))

(Preparation of solar cell substrate)
Next, the diffraction grating precursor layer 2 is laminated on one surface of the transparent substrate 1. (See Fig. 4 (a))

As a material of the transparent substrate 1, a single plastic film or laminated plastic film having a glass transition point of 240 ° C. or higher, chemically tempered glass, or physically tempered glass can be used.

As a plastic film material having a glass transition point (Tg) of 240 ° C. or higher, a polyimide resin (glass transition point (Tg); about 260 ° C.) or an aramid resin (glass transition point (Tg); about 355 ° C.) should be used. However, a polyimide resin is preferable from the viewpoint of transparency.

Chemically strengthened glass is chemically strengthened in soda glass, lime glass, silicate glass, etc. (alkaline salts such as nitrates and sulfates are heated and melted, and the glass to be treated is immersed in the melt for several hours to several tens of hours. However, from the viewpoint of high mechanical strength, a product obtained by subjecting alumina silicate glass to chemical strengthening treatment is preferable.

The alumina silicate glass, preferably those _Al 2 _{O 3} content of not less than 10 wt%, still more preferably as long as it contains the _A1 2 _{O 3} of 15 to 30 wt%.

As the physically tempered glass, a material obtained by subjecting soda glass, lime glass, silicate glass or the like to physical tempering treatment (air cooling or liquid cooling treatment) can be used. From the viewpoint of high mechanical strength, alumina silica The thing which gave the physical strengthening process to the acid glass is preferable.

The alumina silicate glass, preferably those _Al 2 _{O 3} content of not less than 10 wt%, still more preferably as long as it contains the _A1 2 _{O 3} of 15 to 30 wt%.

As a material for the diffraction grating precursor layer 2, an ionizing radiation curable resin, thermosetting resin or cast resin having a glass transition point (Tg) of 240 ° C. or higher and transparency can be used. From the viewpoint that it is not necessary to apply a thermal load to the transparent substrate 1 when forming the layer, ionizing radiation curable resins are preferred.

The ionizing radiation curable resin is not particularly limited as long as it is a resin that is cured by irradiation with ionizing radiation. For example, a γ ray curable resin, an ultraviolet curable resin, and an electron beam curable resin can be used. From the viewpoint of extremely small volume shrinkage, an ultraviolet curable resin is preferable.

As an ultraviolet curable resin, a prepolymer of a polyimide resin (glass transition point (Tg); about 260 ° C.) or an aramid resin (glass transition point (Tg); about 355 ° C.) is used for adjusting the viscosity or the crosslinking density. A resin to which a polyfunctional or monofunctional monomer, a photoinitiator and a sensitizer are added can be used.

Thermosetting resins include polyimide resins (glass transition point (Tg); about 260 ° C.) and aramid resins (glass transition point (Tg); about 355 ° C.) as main components, and curing of crosslinking agents, polymerization initiators, etc. A resin to which an agent or a polymerization accelerator is added can be used, but a resin containing a polyimide resin as a main component is preferable from the viewpoint of a low curing temperature.

The cast resin is mainly composed of a reactive mixed resin containing one or more aliphatic isocyanate prepolymers and one or more polyether polyols, and promotes adhesion between the transparent substrate 1 and the diffraction grating layer 2. For this purpose, a resin added with an adhesion promoter and a curing reaction promoting catalyst can be used.

As the adhesion promoter, silane, aminosilane, or the like can be used, but aminosilane is preferable from the viewpoint of a high adhesion reaction rate.

Dibutyltin dilaurate can be used as the catalyst for accelerating the curing reaction.

As a method for laminating the diffraction grating precursor layer 2, the UV curable polyimide resin is diluted with a solvent (for example, when an ultraviolet curable resin (ionizing radiation curable polyimide resin) is used as the material of the diffraction grating precursor layer 2). A paste that is applied to the transparent substrate 1 by a die coating method, a spin coating method, a screen printing method, a bar coating method, a gravure coating method, or a dip coating method, and then dried. However, the dip coating method is preferable from the viewpoint of yield of the paste (expensive) used.

The solvent is not particularly limited as long as it has an appropriate boiling point. For example, methyl ethyl ketone (MEK), acetone, methyl isobutyl ketone, methanol, ethanol, isopropanol, butanol, tetrahydrofuran, dioxane, dimethylformamide, dimethylacetamide, N-methylpyrrolidone can be used. For example, when dissolving an ultraviolet curable polyimide resin, methyl ethyl ketone (MEK) is preferable from the viewpoint of solubility.

Next, the stamper 500 is pressed against the diffraction grating precursor layer 2 to form a diffraction grating pattern 2 ′. (See Fig. 4 (b))

Next, the diffraction grating layer 2 ″ is formed by curing the diffraction grating pattern 2 ′. (See Fig. 4 (c))

As a method of curing, use a method of heating and a method of irradiating ionizing radiation such as γ-ray irradiation, ultraviolet irradiation, electron beam irradiation (selecting in consideration of the diffraction grating pattern 2 ′ constituent resin). Can do.

When irradiating ultraviolet rays, it is preferable to irradiate ultraviolet rays in a wavelength region of 100 to 380 nm using a carbon arc, a metal halide lamp, an ultra-high pressure mercury lamp, a high-pressure mercury lamp, a low-pressure mercury lamp, etc. (Diffraction having a fine pattern of nm level) From the viewpoint that the lattice layer can be manufactured inexpensively in a short time), it is more preferable to irradiate ultraviolet rays in a wavelength region of 200 to 300 nm.

When irradiating an electron beam, use various electron beam accelerators such as a dynamitron type, a linear type, a cockroft Walton type, a bandegraph type, a resonant transformer type, an insulated core transformer type, a high frequency type, etc., and a wavelength region of 100 nm or less However, it is more preferable to irradiate an electron beam in a wavelength region of 50 nm or less (from the viewpoint that a structure layer having a fine pattern of nm level can be manufactured at a low cost in a short time).

When using the method of irradiating ionizing radiation, the ionizing radiation is irradiated from the opposite side of the stamper 500.

Next, the stamper 500 is removed. (See Fig. 4 (d))

Next, the transparent electrode 3 is formed on the diffraction grating layer 2 ″. (See Fig. 5 (a))

The material of the transparent electrode 3 is a good conductor and has a transparency with a light transmittance of 70% or more in order to efficiently absorb the light from the sun or white fluorescent lamp into the solar cell unit. is not particularly limited as long as, for example, ITO (indium tin oxide) (indium tin oxide), CdO, formula ZnOx (0.8 ≦ x <1) , a metal oxide such as SnO ₂ and _Cd 2 SnO ₄ Ya A metal thin film formed by depositing a metal such as Au, Al, Cu or the like in an extremely thin and translucent form can be used, but ITO is preferable from the viewpoint of low resistance and high transparency.

Although the thickness of the transparent electrode 3 can be selected from the range of 10 nm-300 nm, 20-200 nm is preferable.

When the thickness of the transparent electrode 3 exceeds 200 nm, particularly when it exceeds 300 nm, cracks and the like are likely to occur in the transparent electrode 6.

Moreover, when the thickness of the transparent electrode 3 is less than 20 nm, particularly less than 10 nm, the transparent electrode 3 does not form a continuous film (island-like) and has good conductivity (surface resistance of 10 ³ Ω). / □ or less) is a concern.

As a method for forming the transparent electrode 3, for example, a vacuum deposition method, a sputtering method, an ion plating method, a CVD (Chemical Vapor Deposition) method, a DC magnetron sputtering method, or the like can be used. From this viewpoint, the DC magnetron sputtering method is preferable.

(Production of solar cell module)
First, the solar cell unit 4 is formed on the transparent electrode 3. (See FIG. 5 (b))

The thickness of the p layer can be selected from a range of 1 nm to 10 nm, but 4 to 6 nm is preferable from the viewpoint of pinholeless and low cost.

Although the thickness of i layer can be selected from the range of 280 nm-320 nm, 290-310 nm is preferable.

Although the thickness of n layer can be selected from the range of 30 nm-70 nm, 40-60 nm is preferable.

As a method for forming the solar cell unit 4, for example, a vacuum deposition method, a sputtering method, an ion plating method, a CVD (Chemical Vapor Deposition) method, and a PCVD (Plasma CVD) method can be used. From the viewpoint of being fast, the PCVD method is preferable.

Finally, the solar cell module is obtained by laminating the back electrode 5 on the solar cell unit 4. (See Fig. 5 (c))

The material of the back electrode 5 is not particularly limited as long as it is a good conductor with high light reflectivity. For example, silver, copper, or aluminum can be used, but a long wavelength (wavelength of about 600 nm) transmitted through the solar cell unit 4 can be used. From the viewpoint of high light reflectance, silver is preferable.

As a method for laminating the back electrode 5, for example, a vacuum deposition method or a sputtering method can be used. From the viewpoint that the back electrode 5 having excellent surface specularity (smoothness) can be formed, the sputtering method is preferable.

Although the thickness of the back electrode 5 can be selected from the range of 220 nm-330 nm, 240-310 nm is preferable.

Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.

Moreover, the evaluation (measurement) of the solar cell produced in the following example is based on JIS C8934, using simulated sunlight (spectrum: AM1.5, irradiation intensity: 100 mW / cm ² ), irradiation temperature: 25 It carried out on the conditions of (degreeC).

<Example 1>
(Preparation of diffraction grating shape transfer stamper)
First, the surface of a glass plate (manufactured by Corning, 1737 (trade name)) was cleaned with an automatic cleaning device manufactured by Shimada Rika Co., Ltd., and then this glass plate was HMDS (hexamethyldisilazane) (Tokyo) A vapor treatment was performed for 2 minutes at 90 ° C. using steam produced by Oka Kogyo Co., Ltd. (OAP (trade name)).

Next, a photoresist (positive type photoresist) (manufactured by Tokyo Ohka Kogyo Co., Ltd., OFPR-800 (trade name)) is applied to the vapor treated surface of the glass plate at 4000 rpm for 30 seconds using a spin coater manufactured by Yuasa. The film was applied so that the film thickness was in the range of 3 ± 1 μm under the above spin coating conditions, and then pre-baked for 50 minutes at 90 ° C. in a clean oven manufactured by DAITRON.

Next, the laser interference exposure apparatus is used to enter the pre-baked photoresist from three directions through an optical mask (NA (numerical aperture) 0.90) having a pattern for forming a diffraction grating layer. Exposure was performed by irradiating a HeCd laser having a wavelength of 442 nm at an angle of 40 degrees.

Next, using a 0.3% tetramethylammonium aqueous solution, development processing was performed at 25 ° C. for 60 seconds, and then rinse treatment with ultrapure water was performed for 25 seconds, followed by drying.

Next, in a DC parallel plate type magnetron sputtering apparatus (XM-8 (trade name), manufactured by Va-Rian Co., Ltd.), a Ni target is used as a sputtering target, and an Ar gas having a pressure of 0.3 Pa is used as a sputtering gas. A Ni conductive layer having a thickness of 600 mm was formed on the photoresist by sputtering Ni at a temperature of 5 × 10 ⁻³ Pa and an RF power of 300 W.

Next, the following Ni plating solution was produced.
Nickel sulfamate tetrahydrate ... 500g / L
Boric acid ... 37g / L
pH ... 3.8

Next, the Ni conductive layer is dipped in the Ni plating solution kept at 40 ° C., and plated under the condition of an energization current time integral value of 300 AH, whereby a thickness of 300 μm is formed on the Ni conductive layer. A nickel plating film was formed.

Finally, the diffraction grating shape transfer stamper 500 was obtained by peeling the glass plate (diffraction grating shape transfer stamper substrate) and the photoresist.

(Preparation of solar cell substrate)
First, a paste obtained by diluting an ultraviolet curable polyimide monomer to a solid content of 45% by mass using methyl ethyl ketone (MEK) is coated with a polyimide resin film (product name: Ube Industries, Ltd. (trade name; The film was applied on Iupirex S)) to a film thickness of 3 ± 1 μm, and then preliminarily dried at 60 ° C.

Next, after applying pressure of 1 MPa to the coated surface and pressing the diffraction grating shape transfer stamper for 1 minute, the ultraviolet curable type is irradiated with ultraviolet light having a wavelength of 250 nm from the polyimide resin film side at an energy of 750 mJ / cm ^2. The diffraction grating layer was formed by curing the polyimide resin, and then the diffraction grating forming stamper was removed.

A solar cell substrate on which a diffraction grating layer is formed and an ITO target are mounted on a DC magnetron sputtering apparatus, the temperature in the deposition chamber is 25 ° C., the argon partial pressure is 6 × 10 ⁻³ Torr, and the oxygen partial pressure is 1 ×. A transparent electrode having a thickness of 280 nm was formed by discharging the ITO target at 10 ⁻⁴ Torr and discharging at a discharge power of 200 W.

(Production of solar cell module)
Next, the solar cell substrate is mounted on the plasma CVD apparatus so that the transparent substrate surface is in contact with the heater, and then vacuum is applied using a vacuum pump until the pressure in the film formation chamber becomes 4 × 10 ⁻⁷ Torr. After exhausting, the solar cell substrate was heated to 190 ± 1 ° C. using a heater.

Next, as source gases, silane (SiH ₄ ) (1.2 sccm), tetramethylsilane ((CH ₃ ) ₄ Si) (2 sccm), hydrogen (H ₂ ) (600 sccm), diborane (B ₂ H ₆ ) (0.02 sccm) was introduced.

After introducing the source gas, the pressure in the film forming chamber was controlled to 1.0 ± 0.1 Torr using a pressure controller.

Next, plasma was generated by supplying 100 MHz high frequency power to the discharge electrode from the high frequency power source via the impedance matching unit, and a 5 nm thick p layer was formed.

Next, the temperature in the film formation chamber was set to 110 ± 1 ° C., the pressure was set to 5 × 10 ⁻⁸ Torr, and then silane (SiH ₄ ) (100 sccm) was introduced as a source gas into the film formation chamber.

After introducing the source gas, the pressure in the film forming chamber was controlled to 75 ± 1 mTorr using a pressure control device.

Next, plasma was generated by supplying 100 MHz high frequency power to the discharge electrode from the high frequency power source via the impedance matching unit, and an i layer having a thickness of 300 nm was formed.

Next, the temperature in the film forming chamber is set to 180 ± 1 ° C., the pressure is set to 6.8 × 10 ⁻⁹ Torr, and then silane (SiH ₄ ) (100 sccm), hydrogen (H ₂ ) (1600 sccm), PH ₃ (67 sccm) was introduced into the deposition chamber.

After introducing the source gas, the pressure in the film forming chamber was controlled to 75 ± 1 mTorr using a pressure control device.

Next, plasma was generated by supplying 100 MHz high frequency power to the discharge electrode from a high frequency power source via an impedance matching unit, and an n layer having a thickness of 50 ± 1 nm was formed.

Finally, the substrate on which the n-layer is formed and the Ag target are mounted on a magnetron sputtering apparatus, the temperature in the film forming chamber is 25 ° C., the pressure is 2 mTorr, and RF discharge is performed with a discharge power of 200 W to sputter the Ag target. Thus, a solar cell module was obtained by forming a back electrode having a thickness of 280 nm.

A substrate for a solar cell, a solar cell module, and a solar cell device of the present invention are a portable small electric device such as a camera, a mobile phone, a notebook computer, a PDA (Personal Digital Assistant), a navigation system, and a portable music player, and It can be used as a power source for electric vehicles, vending machines, spacecrafts, etc.

It is a figure for demonstrating the dimension of the honeycomb structure of the board | substrate for solar cells of this invention. It is sectional drawing which looked at the diffraction grating layer of the board | substrate for solar cells of this invention from the thickness direction of the board | substrate for solar cells. It is sectional drawing for demonstrating the manufacturing method of the stamper used for preparation of the board | substrate for solar cells of this invention. It is a figure for demonstrating the manufacturing method of the board | substrate for solar cells of this invention. It is a figure for demonstrating the manufacturing method of the board | substrate for solar cells of this invention, and a solar cell module. It is a schematic diagram of the solar cell apparatus of this invention.

Explanation of symbols

1 .... Transparent insulating substrate 2 ... Diffraction grating precursor layer 2 '... Diffraction grating pattern 2 "... Diffraction grating layer 3 ... ·········································································· Reflector 100 .... Photoresist 200 '... Solubilized photoresist 200 "... Photoresist 300 ... Conductive layer 400 ... Metal layer 500 ... Diffraction Lattice shape transfer stamper

Claims (9)

A substrate for a solar cell comprising a transparent insulating substrate and a diffraction grating layer formed on the transparent insulating substrate and having a texture structure on the surface,
The substrate for a solar cell, wherein the diffraction grating layer contains a light-transmitting insulating resin as a main component. 2. The translucent insulating resin has a glass transition point (Tg) of 240 ° C. or higher and contains an ionizing radiation curable resin, a thermosetting resin, or a cast resin as a main component. Solar cell substrate. The solar cell substrate according to claim 1, wherein the transparent insulating substrate is chemically tempered glass or physical tempered glass. The solar cell substrate according to claim 1 or 2, wherein the transparent insulating substrate is a single plastic film or a laminated plastic film having a glass transition point (Tg) of 240 ° C or higher. The diffraction grating layer has a honeycomb structure, and the length of one side (L in FIG. 1) constituting the honeycomb structure is 100 to 10,000 nm,
The cell partition wall thickness (W in FIG. 1) is 10 to 300 nm,
The ratio of the cell partition wall height (H in FIG. 1) to the cell partition wall thickness (W in FIG. 1) is in the range of 1/8 to 5/4. The solar cell substrate according to any one of the preceding claims. The diffraction grating layer has a structure in which convex portions and concave portions are periodically arranged two-dimensionally, and the shape of the convex portion viewed from the thickness direction of the diffraction grating is circular. The board | substrate for solar cells of any one of Claim 4. A solar cell substrate, wherein a transparent electrode is formed on the diffraction grating layer of the solar cell substrate according to any one of claims 1 to 6. A solar cell unit formed on the transparent electrode;
A back electrode formed on the solar cell unit;
A solar cell module. A solar cell device, wherein the solar cell module is surrounded by a light reflecting material having a light incident surface of the solar cell module as an opening.