JP2003229584A - Glass substrate for photoelectric converter and photoelectric converter using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a glass substrate for a photoelectric converter capable of simultaneously demonstrating a reflection reducing function and an antiglare function and performing lasting effects of the functions, and to provide the photoelectric converter in which photoelectric conversion efficiency is high due to the reflection reducing function and the antiglare function, and the high photoelectric conversion efficiency is maintained for a long time. <P>SOLUTION: In the glass substrate for the photoelectric converter, the glass substrate 5 is provided with a rough surface and a transparent conductive film 3 formed on the other surface. The average reflectance of a wavelength 400 to 1,100 nm measured from the side of the rough surface is ≤9% and 20-degree specular gloss, 45-degree specular gloss and 60-degree specular gloss on the rough surface are all ≤50. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric conversion device using a glass substrate that can simultaneously exhibit a reflection reducing function and an antiglare function.

[0002]

2. Description of the Related Art Due to an increasing awareness of environmental problems in recent years, photoelectric conversion devices such as solar cells are rapidly spreading. In recent years, in particular, thin-film photoelectric conversion devices using amorphous silicon for the photoelectric conversion layer have become the mainstream. The thin-film photoelectric conversion device has a low manufacturing cost, and it is considered that the recent remarkable technological development has brought about a photoelectric conversion efficiency substantially comparable to that of the crystal type. The basic structure of an amorphous silicon solar cell, which is a thin-film photoelectric conversion device, consists of a transparent conductive film made of tin oxide, a photoelectric conversion layer made of amorphous silicon, and a back electrode made of a silver thin film on a transparent substrate such as glass. Are laminated in this order. Then, light enters the photoelectric conversion layer from the transparent substrate side. The photoelectric conversion efficiency of the photoelectric conversion device is proportional to the amount of light guided to the photoelectric conversion layer and the path length of incident light in the photoelectric conversion layer, except for the physical properties of the photoelectric conversion layer. Therefore, the transparent substrate is required to have a high transmittance and a function of appropriately scattering incident light. This is because if the transmittance is high, the amount of light incident on the photoelectric conversion layer increases, and if the incident light is appropriately scattered, the path length of the incident light in the photoelectric conversion layer is extended. As a means for increasing the transmittance, a method of reducing the absorbance by thinning the transparent substrate or changing the composition,
Alternatively, a method of adjusting the surface condition of the transparent substrate to reduce the surface reflectance (so-called AR processing) is generally used.
For example, Japanese Patent Application No. 2000-385093 describes an antireflection film in which fine particles having a particle size of about 100 nm are adhered to the surface of a glass plate by a sol-gel method. As a means for scattering the incident light, a method of intentionally roughening the surface of the transparent substrate or the surface of the transparent conductive film so that the incident light is scattered to increase the haze ratio is often used. For example, Japanese Unexamined Patent Publication No. 6-244444 discloses a method of forming irregularities having a repeating width from infrared to visible light wavelength or less on the surface of a transparent substrate.

Further, since the photoelectric conversion device, particularly a solar cell, is generally attached to the outer wall of a building or the roof of a house, it is easily noticeable and may cause so-called reflection pollution that reflects sunlight glaringly. As a means for reducing reflection pollution, a method of intentionally roughening the surface of the transparent substrate so that reflected light is scattered there (so-called antiglare processing) is generally used. For example, Japanese Patent Application Laid-Open No. 2
JP-A-001-168360 describes a solar cell in which organic material particles or inorganic material particles are applied to the surface of a glass plate.

Further, the solar cell is required to have durability so that AR processing or anti-glare processing does not deteriorate even in such a bad environment because the solar cell is constantly exposed to sunlight and exposed to wind and rain.

[0005]

However, the conventional AR
In the processing, silica fine particles of an appropriate size are bonded using a binder so that irregularities having a size of a fraction of the visible light wavelength are formed on the surface of the transparent substrate. On the other hand, in anti-glare processing, it is found in commercially available template glass (glass plate with a continuous geometric pattern on the surface) or frosted glass (glass plate whose surface is polished with gold sand and a gold brush). As described above, it is common to provide the surface of the transparent substrate with irregularities that are several hundred times the wavelength of visible light. As described above, in the AR processing and the antiglare processing, since the size of the unevenness provided on the surface of the transparent substrate has a significant difference, it is conventionally considered that there is a surface state of the transparent substrate capable of simultaneously satisfying these effects. There wasn't.

Further, an AR having the above silica fine particles attached thereto
In the processing, although the silica fine particles were bonded to the transparent substrate with the binder, the peeling could not be completely prevented during long-term use.

The present invention has been completed in view of such problems. The purpose is AR
It is an object of the present invention to provide a glass substrate for a photoelectric conversion device, which can exhibit the function and the antiglare function at the same time and can permanently exhibit the effect based on the function. Further, it is to provide a photoelectric conversion device having a high photoelectric conversion efficiency based on the AR function and the antiglare function, and the high photoelectric conversion efficiency is permanently maintained.

[0008]

In order to solve the above-mentioned problems, the glass substrate for a photoelectric conversion device according to the present invention comprises an uneven surface and a transparent conductive film formed on the opposite surface thereof. A glass substrate provided, having an average reflectance of 9% or less at a wavelength of 400 to 1,100 nm measured from the uneven surface side, and having a 20-degree specular gloss, a 45-degree specular gloss and a 60-degree specular gloss on the irregular surface. Are all 50 or less.

The glass substrate for a photoelectric conversion device according to a second aspect of the present invention is the glass substrate for a photoelectric conversion device according to the first aspect of the present invention, with respect to the uneven surface, the height of the protrusion has a mode value of 100 to 1,000.
nm, 70% or more are distributed in the range of 50 to 5,000 nm, and the width of the convex portion has a mode value of 200 to
70 at 1,200 nm in the range of 50 to 5,000 nm
% Or more are distributed.

A glass substrate for a photoelectric conversion device according to a third aspect of the present invention is the glass substrate for a photoelectric conversion device according to the first or second aspect,
Regarding the light transmitted from the uneven surface side to the transparent conductive film side, the haze ratio of the transparent conductive film is 10% or more.

A glass substrate for a photoelectric conversion device according to a fourth aspect of the present invention is the glass substrate for a photoelectric conversion device according to any one of the first to third aspects, in which a refractive index of 1. 6 to 2.5 and a first layer having a thickness of 5 to 100 nm, a refractive index of 1.4 to 2.0, and a thickness of 5 to 100 nm
A second layer of the undercoat film.

According to a fifth aspect of the invention, there is provided a photoelectric conversion device comprising:
The glass substrate according to any one of claims 1 to 4 is used.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. However, it is not limited to the following embodiments.

In the present invention, a glass substrate is used as the transparent substrate, and the surface of the glass substrate itself is made uneven so that the AR function and the antiglare function are simultaneously exhibited.
For example, the surface of the glass substrate can be made uneven by using an extraneous substance other than the glass substrate, such as attaching silica fine particles. Further, there is an advantage that the AR function can be improved by selecting and using an extraneous substance having a refractive index different from that of the glass substrate. However, when foreign matter is used, even if it is adhered to the glass substrate with a binder, it cannot be denied that it lacks in integrity and is inferior in durability as compared with the case where the surface of the glass substrate itself is made uneven. Further, a step of manufacturing / adjusting the foreign matter and a step of adhering the foreign matter to the glass substrate are separately required, which causes a problem that the manufacturing process of the glass substrate is complicated and the manufacturing cost is increased. Therefore, the present invention has been studied on the premise that the surface of the glass substrate itself is made uneven.

The glass substrate that exhibits the antiglare function and the AR function at the same time can be specified by the following characteristics.
That is, for the glass substrate provided with the transparent conductive film on the surface facing the uneven surface, the wavelength 40 measured from the uneven surface side.
The average reflectance at 0 to 1,100 nm is 9% or less, and the 20-degree specular gloss, 45-degree specular gloss and 60-degree specular gloss on the uneven surface are all 50 or less. The average reflectance is a value measured in the state where the photoelectric conversion layer is not provided on the transparent conductive film, and the 20-degree specular gloss, 45-degree specular gloss and 60-degree specular gloss are as follows.
It is a value measured according to the specular glossiness measuring method of JIS Z 8741-1983.

This average reflectance is an index for evaluating the AR function. The average reflectance of the conventional template glass is somewhat different depending on the shape of the mold or the glass composition,
When a transparent conductive film is provided on this, at least 9.3%
That is all. On the other hand, the indexes for evaluating the antiglare function are three glossinesses of 20 degree specular glossiness, 45 degree specular glossiness and 60 degree specular glossiness. By using the values measured at three different angles for evaluation, the reliability as an index is secured. By the way, the specular gloss of a glass substrate (having a conventional glass substrate having an AR function, a base film and a transparent conductive film described below) to which silica fine particles having a particle diameter of about 100 nm are bonded with a binder containing a silane coupling agent is as follows.
Both are about 120.

Further, the present inventors have found that wavelengths of 400 to 1,1
We have succeeded in producing a glass substrate with an average reflectance at 00 nm of 8.5% or less, and 20 or less specular gloss, 45 or 60 degree specular gloss on an uneven surface. .

As one form that embodies the characteristics of this glass substrate, the uneven surface of the glass substrate is set to the following state. That is, regarding the height of the convex portion, the mode value is 1
70-70% or more is distributed in the range of 50 to 5,000 nm in the range of 00 to 1,000 nm, and the mode of the width of the convex portion is 200 to 1,200 nm and 50 to 5,000 nm.
70% or more is distributed in the range. Here, a method of measuring the height of the convex portion and the width of the convex portion will be described.
The height of the convex portion is calculated based on a scanning electron microscope (SEM) photograph taken from above with an elevation angle of 30 ° at a magnification of 45,000. Specifically, regarding the convex part where the full shadow appears in the SEM photograph, the line connecting the points where the protrusion of each convex part starts (usually the apex of the concave part) is taken as the baseline, and the base from the top of the convex part A vertical line is drawn on the line, and the length of the vertical line is regarded as the height. In addition, the width of the convex portion is obtained by calculating the distance between the crown of a certain convex portion and the crown of the convex portion closest to the convex portion in which the full shadow appears in the SEM photograph, based on the SEM photograph.

The height of the convex portion and the width of the convex portion are distributed according to a normal distribution function, and there is almost no convex portion having a protruding size with some variation. The phrase “follows a normal distribution function” means that the mode value and the average value can be identified with each other, and the graph of the distribution function is substantially bilaterally symmetric with respect to the mode value.

As described above, the size of the irregularities on the surface of the glass substrate must be smaller than the visible light wavelength in order to exert the AR function, while the visible light wavelength is required in order to exert the antiglare function. Larger and some variation is required. Further, if there are too many large convex portions, the reflectance increases due to irregular reflection, while if there are too many small convex portions, the light almost goes straight and the antiglare function is not exerted. The present inventors carried out many experiments in consideration of such conditions and, as a result, found a preferable state regarding the above-mentioned uneven surface.

The method of embodying the above-mentioned uneven surface state is as follows:
It is not particularly limited. For example, a method of performing dry etching after pattern formation by interference exposure, a scribe method using a laser, or a blast method in which the grain size of abrasive grains is adjusted can be cited.

The type of glass substrate is not limited, and commercially available glass such as soda lime glass, borosilicate glass, aluminosilicate glass or silica glass can be used as it is. Among them, soda lime glass produced in large quantities by the float method is preferable in terms of easy availability and cost. It should be noted that soda lime glass of various colors containing trace elements may be used, but if high transmittance in a wide wavelength range is expected, the iron content should be 0.
It is desirable to set it to 03% or less.

A transparent conductive film is provided on the surface of the glass substrate facing the uneven surface. This transparent conductive film functions as a transparent electrode in the photoelectric conversion device. It is preferable that the transparent conductive film contains tin oxide, titanium oxide, zinc oxide, or tin oxide doped with indium (ITO) as a main component. Among them, the transparent conductive film containing tin oxide as a main component is advantageous in that it can be formed into a large area in a short time by a chemical vapor deposition method (CVD method) using an inexpensive raw material. Especially,
In the glass manufacturing process by the float method, the heat of the glass ribbon in a molten state is used to advance the thermal decomposition reaction C
If the VD method is used, the molding cost of the transparent conductive film can be significantly reduced. The transparent conductive film containing tin oxide as the main component should be doped with fluorine or antimony in order to increase the conductivity. The preferable fluorine concentration in the transparent conductive film is 0.4% by weight or less, and the refractive index at this time is about 1.9. Also, silicon, aluminum, zinc,
A small amount of copper, indium, bismuth, gallium, boron, vanadium, manganese, zirconium, or the like may be doped. However, these concentrations are 0.02% by weight
The following are preferred. Specifically, the sheet resistance value of the transparent conductive film is preferably 3 to 30 Ω / □ (square). Considering this value, the preferable thickness of the transparent conductive film is 500 to 1,
It becomes 500 nm. In each of the above applications, the glass substrate is arranged so that the uneven surface is on the incident light side.

When a transparent conductive film containing tin oxide as a main component is formed by the CVD method, the tin raw material may be tin tetrachloride, dimethyltin dichloride, dibutyltin dichloride, tetramethyltin, tetrabutyltin, dioctyltin dichloride or monobutyltin. Examples thereof include trichloride, and tin tetrachloride or organotin chloride such as dimethyltin dichloride or monobutyltin trichloride is particularly preferable. The oxidizing raw material used for converting the tin raw material into tin oxide may be oxygen, water vapor, dry air, or the like. Examples of the fluorine raw material include hydrogen fluoride, trifluoroacetic acid, bromotrifluoromethane, chlorodifluoromethane and the like. When antimony is added, antimony pentachloride or antimony trichloride may be used.

By thus forming the surface irregularities on one main surface of the glass substrate and forming the transparent conductive film on the opposite surface thereof, the glass substrate can be used for a photoelectric conversion device. Then, a large amount of light is guided to the photoelectric conversion layer based on the AR function derived from the surface irregularities, the photoelectric conversion efficiency of the photoelectric conversion device is increased, and reflection pollution by the solar cell is suppressed based on the antiglare function. Further, the AR function and the antiglare function are permanently exhibited based on the fact that the surface irregularities are the surface shape of the glass substrate itself.

A thickness of 5 is provided between the glass substrate and the transparent conductive film.
It is desirable to provide a base film mainly composed of silica or aluminum oxide having a thickness of 150 nm. By providing the base film, it is possible to reduce interference of reflected light and further reduce the average reflectance. The base film is not limited to one layer and may be two layers. In the case of two layers, the preferable film thickness of the first layer is 5 to 100 nm, and the preferable refractive index is 1.6 to 2.5. The first layer is preferably composed of at least one selected from tin oxide, titanium oxide and aluminum oxide. The preferable film thickness of the second layer is 5 to 100 nm, and the preferable refractive index is 1.4 to 2.
It is 0. The second layer is preferably composed of at least one selected from silica, aluminum oxide and tin oxide. Further, the refractive index of the first layer is preferably higher than the refractive index of the second layer. The base film is not limited to a one-layer or two-layer structure, and may have three or more layers.

When silica, which is suitable as the base film, is formed by the CVD method, monosilane,
Disilane, trisilane, monochlorosilane, dichlorosilane, 1,2 dimethylsilane, 1,1,2 trimethyldisilane,
Examples include 1,1,2,2 tetramethyldisilane, tetramethylorthosilicate, tetraethylorthosilicate and the like. Further, as the oxidizing raw material in this case, oxygen,
Examples thereof include steam, dry air, carbon dioxide, carbon monoxide, nitrogen dioxide or ozone. When using silane, an unsaturated hydrocarbon gas such as ethylene, acetylene, or toluene may be used in combination for the purpose of preventing the reaction of silane until it reaches the surface of the glass substrate.
Similarly, when forming an aluminum oxide film, examples of the aluminum raw material include trimethylaluminum, aluminum triisopopropoxide, diethylaluminum chloride, aluminum acetylacetonate, and aluminum chloride. The oxidizing raw material in this case may be oxygen steam or dry air.

Since the surface irregularities of this glass substrate are dispersed appropriately, the transmitted light is scattered on the surface of the irregularities so that the so-called optical confinement effect in which the optical path in the photoelectric conversion layer is lengthened is effectively exhibited. become. If the distribution of the height of the convex portion and the width of the convex portion is as described above, there is almost no convex and large convex portion even though the size of the convex portion has some variation. In order for the light confinement effect to be effectively exhibited, both the height of the convex portion and the width of the convex portion must be about the visible light wavelength, while in order to cause light scattering at various wavelengths, the convex portion Both the height and the width of the convex portions need to be distributed with appropriate variations. However, if there are too many large convex portions, the reflectance increases due to irregular reflection, and the amount of light incident on the photoelectric conversion layer decreases. If there are too many small convex portions, the light confining effect cannot be obtained because the transmitted light is not sufficiently scattered, and further, the reflected light is not sufficiently scattered and the antiglare function is not exhibited. Therefore, it can be said that the ideal state is the state in which the heights of the protrusions and the widths of the protrusions are both distributed according to the normal distribution function, like the uneven surface of the glass substrate. Further, when there are many convex portions having a height or width of less than 50 nm, the transmitted light is not scattered, so that the light trapping effect is not sufficiently exhibited. on the other hand,
Convex portion with a height exceeding 1,000 nm or 1,200 n
If there are many convex portions having a width exceeding m, the average reflectance does not decrease, and therefore the amount of light incident on the photoelectric conversion layer does not increase.

By the way, when the above-mentioned average reflectance is measured after the underlying film and / or the transparent conductive film is provided, the loss of light from the end face of the glass cannot be ignored and accurate measurement may be difficult. The reduction in reflectance may be replaced with the increase in transmittance for evaluation. Specifically, in order to eliminate the influence of the surface irregularities of the transparent conductive film, a transparent methylene iodide solution having a refractive index close to that of the transparent conductive film and having no absorption in the visible light range is applied to the surface of the transparent conductive film. Then, a cover glass is attached on it, and the "immersion liquid permeability" is measured. When evaluated by this immersion liquid transmittance, the presence of the uneven surface of the glass substrate improves the average immersion liquid transmittance at wavelengths of 400 to 1,100 nm by 0.5% or more (the average reflectance decreases by this improvement). Is preferable), and 1.0 is more preferable.
% Or more is preferable.

When this glass substrate is used, not only when the photoelectric conversion layer is amorphous silicon but also in the case of amorphous silicon germanium or thin film polycrystalline silicon, which is the mainstream of the next generation, such as thin film type solar cells and crystalline silicon solar cell covers. Even when it is used for glass, it is expected that the AR function and the antiglare function will be exhibited and the conversion efficiency of the photoelectric conversion device will be improved.

FIG. 1 is a sectional view of one form of this photoelectric conversion device. In this photoelectric conversion device, the base films 1 and 2, the transparent conductive film 3, the photoelectric conversion layer 7, and the back surface electrode 8 are formed in this order on the opposite surface of the uneven surface.

The amorphous silicon layer is formed by, for example, a vapor deposition method or a plasma CVD method using glow discharge using a raw material of monosilane diluted with hydrogen gas or a thermal CVD method. The amorphous silicon layer is usually p-
methane, diborane, as appropriate to form an in junction.
It is formed by forming a p-layer, an i-layer, and an n-layer in order from the transparent conductive film side while adding phosphine or the like. However, instead of amorphous silicon, amorphous silicon germanium, microcrystalline silicon, polycrystalline silicon, crystalline silicon, or a compound semiconductor thin film such as CdTe or CuInSe ₂ may be formed as the photoelectric conversion layer. Before forming the back surface electrode, a thin film of zinc oxide may be formed in advance for the purpose of improving reflectance and preventing diffusion of impurities.

The surface irregularities of the photoelectric conversion layer depend on the surface shape of the transparent conductive film. Further, by utilizing an etching method, a blast method, a stamping method, or the like, the surface uneven shape of the photoelectric conversion layer can be controlled. Further, a back electrode made of the same material as the transparent conductive film or a silver film, an aluminum film, or the like is formed on the photoelectric conversion layer.

The photoelectric conversion layer may be a single layer as shown in FIG. 1 or may be a plurality of layers. As the photoelectric conversion layer, a unit composed of an amorphous silicon-based thin film or a crystalline silicon-based thin film (hereinafter, each unit is referred to as an “amorphous silicon-based thin film photoelectric conversion unit” or a “crystalline silicon-based thin film photoelectric conversion unit”). The type of photoelectric conversion layer is quoted as shown below)
Is mentioned.

The amorphous silicon type thin film photoelectric conversion unit is formed by depositing the respective semiconductor layers by the plasma CVD method in the order of pin type. Specifically, for example, a p-type microcrystalline silicon-based layer doped with 0.01 atom% or more of boron, which is a conductivity-type determining impurity atom, an intrinsic amorphous silicon layer that serves as a photoelectric conversion layer, and a conductivity-type determining impurity atom. The n-type microcrystalline silicon-based layer doped with 0.01% or more of phosphorus may be deposited in this order. However, each of these layers is not limited to the above, for example, the impurity atoms in the p-type microcrystalline silicon-based layer may be aluminum or the like, and an amorphous silicon-based layer may be used as the p-type layer.
Alternatively, an alloy material such as amorphous or microcrystalline silicon carbide or silicon germanium may be used for the p-type layer. The thickness of the conductive type (p type, n type) microcrystalline silicon-based layer is preferably 3 to 100 nm, and 5 to 5
0 nm is more preferable.

The intrinsic amorphous silicon layer is formed by plasma CVD.
It is preferable to form a film at 450 ° C. or lower by the method. This layer is formed as a thin film which is a substantially intrinsic semiconductor having a density of conductivity determining impurity atoms of 1 × 10 ¹⁸ cm ⁻³ or less. The thickness of the intrinsic amorphous silicon layer is 0.05 to 0.5 μ.
m is preferred. However, in the amorphous silicon-based thin film photoelectric conversion unit, instead of the intrinsic amorphous silicon layer, an amorphous silicon carbide layer which is an alloy material (for example, amorphous silicon containing 10 atomic% or less of carbon is used). An amorphous silicon carbide layer) or an amorphous silicon germanium layer (for example, an amorphous silicon germanium layer made of amorphous silicon containing 30 atomic% or less germanium) may be used.

Also in the crystalline silicon-based thin film photoelectric conversion unit, the p-i-n type semiconductor layers are subjected to plasma CVD in this order in the same procedure as the amorphous silicon-based thin film photoelectric conversion unit.
It can be formed by deposition by a method.

The back electrode 8 is made of aluminum, silver,
It is preferable to form at least one metal layer made of at least one material selected from gold, copper, platinum and chromium by a sputtering method or a vapor deposition method. In addition, tin oxide, between the photoelectric conversion unit and the back electrode,
A layer made of a conductive oxide such as zinc oxide or ITO may be formed.

This photoelectric conversion device preferably includes a crystalline silicon-based thin film photoelectric conversion unit. Compared with the amorphous silicon thin film photoelectric conversion unit, this unit has a lower open-circuit voltage and a higher short-circuit current density, so its light transmittance is higher than the sheet resistance of the conductive film on the glass plate. This is because it contributes significantly to the photoelectric conversion efficiency.

In the present invention, the "main component" means that the content of the constituent components is 50% by weight or more according to the conventional practice. Further, even if the amorphous part is partially included, if the volume crystallization fraction is 50% or more, it is regarded as “crystalline”. Furthermore, in addition to amorphous or crystalline silicon, “silicon-based” materials also include semiconductor materials such as amorphous silicon germanium containing 50 atomic% or more of silicon.

[0041]

The present invention will be described in more detail with reference to the following examples. However, the present invention is not limited to the following examples.

Example 1 A soda lime glass having a total iron concentration of 0.02% and a thickness of 4 mm was produced by the float method. In a bath filled with molten tin (hereinafter referred to as "molding bath") that molds a molten glass ribbon to an appropriate thickness, a base film and a transparent conductive film are continuously formed on the glass ribbon by the CVD method. It was molded. 98% by volume of nitrogen and 2% by volume of hydrogen are continuously supplied to the molding bath so that the inside of the molding bath is maintained at a slightly higher pressure than the outside of the tank, and the molding bath is kept in a non-oxidizing atmosphere. The film was formed while With the first coater located on the most upstream side stopped, from the second coater immediately behind it, monosilane, ethylene,
A mixed gas consisting of oxygen and nitrogen is supplied and the thickness is 40n.
A base film made of silicon oxide of m was formed. Then, a mixed gas composed of dimethyltin dichloride (vapor), oxygen, water vapor, nitrogen, helium and hydrogen fluoride was supplied from the third coater, and a thickness of 850 nm was formed on the base film.
A transparent conductive film made of fluorine-doped tin oxide was molded.

The glass provided with the transparent conductive film was cut into an appropriate size to form a glass substrate, and then patterning was formed by interference exposure on the bottom surface of the glass (the surface that was in contact with molten tin at the time of manufacturing). A dry etching process was performed. The heights of the convex portions of the glass substrate are distributed according to a normal distribution function, the mode value is 600 nm, and 5
90% was from 0 to 5,000 nm. The width of the convex portion is also distributed according to the normal distribution function, and the mode value is 800
95% of those having a wavelength of 50 to 5,000 nm.

Next, on the uneven surface side of this glass substrate, a reflectance spectrum having a wavelength of 400 to 1,100 nm was measured using a spectrophotometer, and the values were averaged by sampling at wavelength intervals of 10 nm. The average reflectance was 8.6%. By the way, the reflectance of the glass substrate provided with the transparent conductive film before the patterning and the dry etching treatment was 9.3%. Subsequently, using a gonio-gloss meter, specular gloss at angles of 20, 45 and 60 degrees was measured. These glossinesses are all 50
The following values were low. Therefore, it can be said that this glass substrate scatters the reflected light well and the anti-glare function is effectively exhibited. Further, the light was incident from the uneven surface side, and the haze ratio of the transparent conductive film on the glass substrate was measured and found to be 18%. Further, a methylene iodide solution was applied to the transparent conductive film, and a cover glass was attached. Wavelength 4
A transmittance spectrum from 00 to 1,100 nm was measured by a spectrophotometer, sampled at wavelength intervals of 10 nm and averaged to calculate an average immersion liquid transmittance.

Further, the durability of the glass substrate (chemical resistance)
In order to confirm the above, this glass substrate was immersed in a 1N sulfuric acid aqueous solution at 23 ° C. for 240 hours, and subsequently immersed in a 1N sodium hydroxide aqueous solution for 240 hours. About the glass substrate after this durability test, by the same means as above,
The average reflectance, specular gloss and immersion liquid transmittance were measured.
The condition and characteristics of the uneven surface of these glass substrates are summarized in "Table 1" below.

[Manufacturing Example 1] A photoelectric conversion device having an amorphous silicon thin film as a photoelectric conversion layer is produced using a glass substrate provided with the above-mentioned transparent conductive film and a glass substrate that has been subjected to the above durability test. did. First, an amorphous silicon thin film having a thickness of 0.3 μm was formed on the transparent conductive film by the plasma CVD method using monosilane and hydrogen as raw materials. Then, a silver thin film (back surface electrode) having a thickness of 300 nm was formed by electron beam evaporation. The photoelectric conversion efficiency of this photoelectric conversion device was measured by a known means. The results are also shown in "Table 1" below.

[Production Example 2] A photoelectric conversion device having a crystalline silicon thin film as a photoelectric conversion layer was prepared by using a glass substrate provided with a transparent conductive film and a glass substrate that has been subjected to the above durability test. . First, a crystalline silicon thin film having a thickness of 2 μm was formed on a transparent conductive film by a plasma CVD method using monosilane and hydrogen as raw materials. Then, a silver thin film (back surface electrode) having a thickness of 300 nm was formed by electron beam evaporation. The photoelectric conversion efficiency of this photoelectric conversion device was measured by a known means. The results are also shown in "Table 1" below.

(Embodiment 2) to (Embodiment 4) In Embodiment 1, a mixed gas composed of dimethyltin dichloride (steam), oxygen, nitrogen and helium was supplied from the stopped first coater, and the mixture was placed on the glass ribbon. A base film (first layer) made of tin oxide having a thickness of 35 nm was formed. Continuing,
A mixed gas composed of monosilane, ethylene, oxygen and nitrogen was supplied from the second coater to form a base film (second layer) composed of silicon oxide having a thickness of 25 nm. Further, a mixed gas composed of dimethyltin dichloride (vapor), oxygen, water vapor, nitrogen, helium and hydrogen fluoride is supplied from the third coater, and transparent conductive film made of tin oxide doped with fluorine having a thickness of 850 nm is formed on the underlying film. The membrane was molded. here,
In each example, by appropriately changing the thickness of the transparent conductive film,
The haze rate was adjusted. Except for this, the uneven surface of the glass substrate was formed in the same manner as in Example 1, and the characteristics thereof were investigated. The constitution and characteristics of the glass substrate in each of these examples and the photoelectric conversion efficiency of the photoelectric conversion device using the same are summarized in "Table 1" below.

(Comparative Example 1) In Example 1, instead of subjecting the bottom surface of the glass substrate to the patterning formation by interference exposure and the dry etching treatment, a frosted glass-like processing treatment was performed using gold sand and a metal brush. Except for this, the characteristics of the glass substrate were investigated in the same manner as in Example 1 to fabricate a photoelectric conversion device. The configuration and characteristics of this glass substrate and the photoelectric conversion efficiency of the photoelectric conversion device are summarized in "Table 1" below. Note that the haze ratio of this glass substrate is different from that of Example 1 in that the transparent conductive film is brought into contact with a jig of a processing device during processing to form a frosted glass, and a convex portion on the surface thereof is formed. It is thought that this is due to some collapse.

(Comparative Example 2) In Example 1, instead of subjecting the bottom surface of the glass substrate to the patterning formation by interference exposure and the dry etching treatment, silica fine particles having an average particle diameter of about 100 nm were applied to the glass substrate surface by the sol-gel method. Then, they were adhered so as to have a closest packing structure. Except for this, the characteristics of the glass substrate were investigated in the same manner as in Example 1 to fabricate a photoelectric conversion device. The structure and characteristics of this glass substrate,
The photoelectric conversion efficiency of the photoelectric conversion device is summarized in "Table 1" below. It is difficult to clarify the technical reason why the haze ratio of this glass substrate is different from that of Example 1, but the present inventors found that It is considered that some kind of interaction is exerted on the irregularities of the film made of silica fine particles, and that the transparent conductive film has a variation due to the measuring point, which is a complex combination.

(Comparative Example 3) In Example 2, instead of subjecting the bottom surface of the glass substrate to the patterning formation by interference exposure and the dry etching treatment, it was processed into a frosted glass using a hard sand and a metal brush. Except for this, the characteristics of the glass substrate were investigated in the same manner as in Example 2 to fabricate a photoelectric conversion device. The configuration and characteristics of this glass substrate and the photoelectric conversion efficiency of the photoelectric conversion device are summarized in "Table 1" below. Note that the haze ratio of this glass substrate is different from that of Example 2 in that, when the glass substrate is processed into a frosted glass, the transparent conductive film comes into contact with a jig of a processing device and a convex portion on the surface thereof. It is thought that this is due to some collapse.

(Comparative Example 4) In Example 2, instead of subjecting the bottom surface of the glass substrate to patterning formation by interference exposure and dry etching treatment, silica fine particles having an average particle diameter of about 100 nm were applied to the glass substrate surface by the sol-gel method. Then, they were adhered so as to have a closest packing structure. Example 2 was changed except that the conditions for performing patterning formation by interference exposure and dry etching treatment on the bottom surface of the glass substrate were changed.
Similarly, the characteristics of the glass substrate were investigated and a photoelectric conversion device was produced. The configuration and characteristics of this glass substrate and the photoelectric conversion efficiency of the photoelectric conversion device are summarized in "Table 1" below. It is difficult to clarify the technical reason why the haze ratio of this glass substrate is different from that of Example 2, but the present inventors found that It is considered that some kind of interaction is exerted on the irregularities of the film made of silica fine particles, and that the transparent conductive film has a variation due to the measuring point, which is a complex combination.

Comparative Example 5 A glass substrate was prepared in the same manner as in Comparative Example 4 except that the thickness of the transparent conductive film was 350 nm, and its characteristics were investigated to prepare a photoelectric conversion device. The configuration and characteristics of this glass substrate and the photoelectric conversion efficiency of the photoelectric conversion device are summarized in "Table 1" below.

[0054]

[Table 1]

By comparing each example and comparative example, the following can be understood. Taking Examples 1 to 4 as a whole,
It can be seen that the average reflectance measured from the uneven surface side and the three specular glosses also change due to changes in the constitution of the underlayer film and the thickness of the transparent conductive film. However, the magnitude of the change is limited, and the characteristics of the glass substrate of the present invention are not lost.

By comparing Examples 1 to 4 with Comparative Examples 2, 4 and 5, when a film made of foreign matter such as silica fine particles is formed on the surface of a glass substrate, even if a foreign matter is used by using a binder, It can be seen that even if it is adhered to the surface of the glass substrate, its durability does not reach that of the glass substrate whose surface itself is uneven.

By comparing Examples 1 to 4 with Comparative Examples 1 and 3, it can be seen that the frosted glass exhibits the anti-glare function but does not exhibit the AR function at all.

On the other hand, by comparing Examples 1 to 4 with Comparative Examples 2, 4 and 5, it can be seen that the film made of silica fine particles can exhibit the AR function but not the antiglare function at all. .

[0059]

Since the present invention is constructed as described above, it has the following effects. According to this invention, since the surface itself of the glass substrate is formed into an appropriate uneven shape, the AR function and the antiglare function are simultaneously exhibited, and the photoelectric conversion device using this glass substrate is high in function based on the function. Photoelectric conversion efficiency can be achieved. Furthermore, these functions are permanently exerted even in a bad environment where the sun is constantly exposed to sunlight and wind and rain.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of one form of a photoelectric conversion element of the present invention.

FIG. 2 is a schematic diagram of an apparatus used for an online CVD method.

[Explanation of symbols]

1 First underlayer 2 Second underlayer 3 Transparent conductive film 4 Convex part of glass substrate surface 5 glass plates 7 Photoelectric conversion layer 8 Back electrode 10 glass ribbon 11 melting furnace 12 tin float tank 13 Annealing furnace 15 Molten tin 16 coater 17 Laura

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshifumi Tsujino             7-28 Kitahama 4-28, Chuo-ku, Osaka City, Osaka Prefecture             Within Nippon Sheet Glass Co., Ltd. (72) Inventor Yasunori Seto             7-28 Kitahama 4-28, Chuo-ku, Osaka City, Osaka Prefecture             Within Nippon Sheet Glass Co., Ltd. F-term (reference) 5F051 AA05 FA02 GA03 GA14

Claims (5)

[Claims] 1. A glass substrate comprising a textured surface and a transparent conductive film formed on a surface facing the textured surface, wherein the average reflectance at a wavelength of 400 to 1,100 nm measured from the textured surface side is 9% or less. A glass substrate for a photoelectric conversion device in which the 20-degree specular gloss, the 45-degree specular gloss, and the 60-degree specular gloss on the uneven surface are all 50 or less. 2. With respect to the uneven surface, the height of the convex portion has a mode value of 100 to 1,000 nm and is 5
70% or more is distributed in the range of 0 to 5,000 nm, and the width of the convex portion has a mode value of 200 to 1,200 nm and is 50
The glass substrate for a photoelectric conversion device according to claim 1, wherein 70% or more is distributed in the range of ˜5,000 nm. 3. The glass substrate for a photoelectric conversion device according to claim 1, wherein the transparent conductive film has a haze ratio of 10% or more with respect to light transmitted from the uneven surface side to the transparent conductive film side. 4. A first layer having a refractive index of 1.6 to 2.5 and a thickness of 5 to 100 nm under the transparent conductive film and a refractive index of 1.4 to 2.0 from the glass substrate side. And thickness 5-10
4. A base film comprising a 0 nm second layer.
The glass substrate for a photoelectric conversion device according to any one of 1. 5. A photoelectric conversion device using the glass substrate according to claim 1.