JP2001060707A - Photoelectric transfer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve photoelectric transfer efficiency of a photoelectric transfer device by a film construction in which intermediate films are formed between a transparent substrate and a transparent conductive film. SOLUTION: A transparent substrate 39, a transparent conductive film 33, a photoelectric transfer units 37 and 38 and a rear side electrode 35 are layered in sequence starting from the side on which luminous rays are incident and intermediate films 31 and 32 are further formed between the transparent substrate and the transparent conductive film. The intermediate films are formed in such a way that the relationship between the average reflectivity R1 in a wavelength range between (λ-50)-(λ+50) and the average reflectivity R2 in the above wavelength range when no intermediate film is formed is R1<=R2×0.8 letting the wavelength of the luminous rays with which spectral-response characteristic of the photoelectric transfer unit becomes maximum is λ nm. Also in the case of a tandem device including a plurality of photoelectric transfer units, intermediate films are formed in such a way that the average reflectivity of each photoelectric transfer unit is decreased in the above wavelength range.

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 such as a solar cell, and more specifically, to improve the photoelectric conversion efficiency of a photoelectric conversion device around a wavelength at which the spectral sensitivity characteristic of the photoelectric conversion unit is maximized. The present invention relates to a photoelectric conversion device having a low light reflectance for incident light.

[0002]

2. Description of the Related Art In a thin film photoelectric conversion device such as a thin film solar cell, a glass plate provided with a transparent conductive film (transparent electrode) is sometimes used. This thin-film photoelectric conversion device is manufactured by forming a transparent conductive film containing tin oxide as a main component, a photoelectric conversion unit including a photoelectric conversion layer, and a back electrode made of aluminum or the like in this order on a glass plate.

As a transparent conductive film, a fluorine-doped tin oxide (hereinafter, referred to as “SnO ₂ : F”) film is frequently used. This film is made of tin-doped indium oxide (I
It has better chemical stability, such as plasma resistance, than the (TO) film, and has little deterioration even when the photoelectric conversion layer is formed by the plasma CVD method. There is also known a thin film photoelectric conversion device in which a base film is formed between a transparent conductive film and a glass plate.
This base film functions as a barrier film for preventing diffusion of an alkali component from the glass plate to the transparent conductive film. As the barrier film, a silicon oxide film is frequently used.

A glass plate provided with a transparent conductive film is also used for a window glass of a building. The glass plate on which the transparent conductive film is formed suppresses the outflow of heat from the opening of the building as so-called Low-E glass. In this application field, it is important to have a natural appearance as a window glass. The tin oxide film is one of the representative transparent conductive films in this field. However, if the tin oxide film is formed to a thickness effective for suppressing the heat loss from the opening, the interference color (glow) of transmitted light may cause a problem. Become. For this reason, Japanese Patent Publication No. 3-72586 discloses that two intermediate layers are formed between a glass plate and a transparent conductive film. Specifically, in this publication, a tin oxide film having a thickness of about 18 nm and a silicon-silicon oxide mixed film having a thickness of about 28 nm are formed in this order from the glass plate side, and a transparent film is formed on these films. A film configuration in which a SnO ₂ : F film having a thickness of about 200 nm is formed as a conductive film is disclosed.

On the other hand, a transparent conductive film used in a thin-film photoelectric conversion device is required to have both high light transmittance and high conductivity, but these two characteristics tend to contradict each other, and it is not easy to achieve both. . For this reason, a thin film photoelectric conversion device using the transparent conductive film itself as an anti-reflection film by adjusting the thickness of the transparent conductive film so that a large amount of light reaches the photoelectric conversion layer has also been proposed (for example, Kiyoshi Takahashi, Makoto Konagai, Amorphous Solar Cell, Shokodo).

[0006]

However, when the transparent conductive film itself is used as an anti-reflection film, the thickness of the transparent conductive film is limited, and it becomes difficult to control the conductivity.
The improvement of the characteristics as the whole photoelectric conversion device cannot be expected. In a photoelectric conversion device including a plurality of photoelectric conversion layers having different spectral sensitivity characteristics, it is difficult to exert an antireflection effect on the plurality of photoelectric conversion layers only by adjusting the thickness of the transparent conductive film.

As described in Japanese Patent Publication No. 3-72586, it has been proposed in the field of architectural window glass to sandwich a plurality of films between a glass plate and a transparent conductive film. However, improvement of the characteristics of the photoelectric conversion device by an intermediate film between the glass plate and the transparent conductive film has not yet been studied. In order to improve the characteristics of the photoelectric conversion device, it is necessary to consider the spectral sensitivity characteristics of the photoelectric conversion layer.

Accordingly, the present invention provides a photoelectric conversion device which adopts a film configuration in which an intermediate film is formed between a transparent substrate and a transparent conductive film, and which improves the photoelectric conversion efficiency by this film configuration. Aim.

[0009]

In order to achieve the above object, a first photoelectric conversion device of the present invention comprises a photoelectric conversion device including a transparent substrate, a transparent conductive film, and a photoelectric conversion layer in order from a light incident side. A photoelectric conversion device in which a unit and a back electrode are stacked, wherein an intermediate film is further formed between the transparent substrate and the transparent conductive film, and a wavelength of the light beam at which a spectral sensitivity characteristic of the photoelectric conversion layer is maximized. Is λ [nm], and (λ
The average reflectance R ₁ in the wavelength range of −50) nm or more and (λ + 50) nm or less and the average reflectance R ₂ in the wavelength range where the intermediate film is not formed are R ₁ <R ₂ × 0.
8 is satisfied.

In a second photoelectric conversion device of the present invention, a transparent substrate, a transparent conductive film, two or more photoelectric conversion units, and a back electrode are laminated in this order from the side where light rays enter, and the two or more photoelectric conversion units are stacked. The unit is a photoelectric conversion device that includes two photoelectric conversion layers in which the wavelength λ of the light beam at which the spectral sensitivity characteristic is maximized is different from each other, further comprising an intermediate film between the transparent substrate and the transparent conductive film. And the wavelengths λ in the two photoelectric conversion layers are respectively λ ₁ [nm],
As λ ₂ [nm], (λ ₁ −50) nm or more and (λ ₁ +5)
0) an average reflectance R ₁₁ in a first wavelength range of not more than nm,
The average reflectance R ₁₂ in the first wavelength band in a state where the intermediate film is not formed satisfies R ₁₁ <R ₁₂ , and (λ ₂
The average reflectance R ₂₁ in the second wavelength range from −50) nm to (λ ₂ +50) nm and the average reflectance R ₂₂ in the second wavelength range in a state where the intermediate film is not formed are R _21.
<And satisfies the R _22.

According to the photoelectric conversion device of the present invention, since the average reflectance is low in a wavelength region where the spectral sensitivity characteristics of the photoelectric conversion unit are high, the photoelectric conversion efficiency of the photoelectric conversion device is improved. In addition, since the reflection in the above wavelength range is suppressed by forming the intermediate film, the thickness of the transparent conductive film is limited for preventing reflection, so that the conductivity is not impaired. Furthermore, corresponding to a plurality of types of photoelectric conversion layers,
The average reflectance in a plurality of wavelength ranges can also be reduced. The average reflectances R ₁ , R ₂ , R ₁₁ , R ₁₂ , R _21, and R ₂₂ have little effect on the relative relationship of the photoelectric conversion unit. It suffices to adopt a value measured in a state where no photoelectric conversion unit is formed on the film.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of one embodiment of the photoelectric conversion device of the present invention. In this thin-film photoelectric conversion device, the first intermediate layer 1 and the second
Intermediate layer 2, transparent conductive film 3, photoelectric conversion unit 4 and back electrode 5 are formed in this order. In this thin-film photoelectric conversion device, the transparent substrate side is the light incident side.

As the photoelectric conversion unit, a unit using an amorphous silicon-based thin film or a crystalline silicon-based thin film as a photoelectric conversion layer (hereinafter, each unit is referred to as an “amorphous silicon-based thin film photoelectric conversion unit”, Such as "system thin film photoelectric conversion unit". The photoelectric conversion unit may be a single layer, or a plurality of layers may be stacked as shown in FIG.

In the thin-film photoelectric conversion device shown in FIG.
A first photoelectric conversion unit 37 and a second photoelectric conversion unit 38 are formed on a photoelectric conversion device substrate 30 on which first and second intermediate layers 31 and 32 and a transparent conductive film 33 are formed in this order on the substrate 9. It is formed in this order, and the back electrode 35
Are formed.

The amorphous silicon thin film photoelectric conversion unit is formed by depositing each semiconductor layer by a plasma CVD method in the order of a pin type. Specifically, for example, a p-type microcrystalline silicon-based layer doped with boron, which is a conductivity type determining impurity atom, in an amount of 0.01 atomic% or more, an intrinsic amorphous silicon layer serving as a photoelectric conversion unit, and a conductivity type determining impurity An n-type microcrystalline silicon-based layer doped with 0.01% or more of phosphorus as an atom may be deposited in this order. However, these layers are not limited to those described above. For example, the impurity atoms may be aluminum in the p-type microcrystalline silicon-based layer, 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 (p-type, n-type) microcrystalline silicon-based layer is preferably 3 nm to 100 nm, more preferably 5 nm to 50 nm.

The intrinsic amorphous silicon layer is formed by plasma CVD.
It is preferable that the base temperature is set to 450 ° C. or lower by a method. This layer is formed as a thin film that is substantially an intrinsic semiconductor in which the density of impurity atoms for determining the conductivity type is 1 × 10 ¹⁸ cm ⁻³ or less. The thickness of the intrinsic amorphous silicon layer is preferably 0.05 μm or more and 0.5 μm or less. However,
In the amorphous silicon-based thin film photoelectric conversion unit, an amorphous silicon carbide layer as an alloy material (for example, amorphous silicon made of amorphous silicon containing 10 atomic% or less of carbon) is used instead of the intrinsic amorphous silicon layer. Quality silicon carbide layer)
Alternatively, an amorphous silicon germanium layer (eg, an amorphous silicon germanium layer made of amorphous silicon containing 30 atomic% or less of germanium) may be formed.

The crystalline silicon-based thin film photoelectric conversion unit can also be formed by depositing pin type semiconductor layers in this order by a plasma CVD method in the same procedure as the amorphous silicon based thin film photoelectric conversion unit.

The photoelectric conversion device of the present invention preferably includes a crystalline silicon-based thin film photoelectric conversion unit. This unit has a lower open-circuit voltage and a higher short-circuit current density than the amorphous silicon-based photoelectric conversion unit, and therefore has a light transmittance higher than the sheet resistance of the conductive film on the glass plate. This is because it greatly contributes to the conversion efficiency. However, in the present invention, a compound semiconductor thin film photoelectric conversion unit using a compound semiconductor material such as GaAs, CdTe, or CIS may be used in addition to the amorphous silicon thin film photoelectric conversion unit.

FIG. 3 shows examples of spectral sensitivity characteristics of the amorphous silicon photoelectric conversion layer and the crystalline silicon photoelectric conversion layer. In the case of amorphous silicon, the spectral sensitivity curve 21 is approximately 500 n
It is maximum at m. On the other hand, in the case of crystalline silicon, the spectral sensitivity curve 22 has a maximum at approximately 750 nm.

In the present specification, the term “crystalline” refers to a “crystalline” material having a volume crystallization fraction of 50% or more even if it contains a partly amorphous material in addition to a polycrystalline material. ". Further, the “silicon-based” material includes a semiconductor material containing 50 atomic% or more of silicon, such as amorphous silicon germanium, in addition to amorphous or crystalline silicon.

As the transparent conductive films 3 and 33, a film containing tin oxide as a main component, specifically, a tin oxide film doped with an impurity such as fluorine is preferable. However, an ITO film or a zinc oxide film may be used as the transparent conductive film, or a multilayer film of these conductive films may be used. The thickness of the transparent conductive film is appropriately determined based on the photoelectric conversion unit to be used and the conductivity required according to the desired photoelectric conversion efficiency.

The first intermediate layers 1 and 31 are preferably formed as high refractive index films having a higher refractive index than the second intermediate layers 2 and 32. As a material of the high refractive index film, at least one selected from tin oxide, titanium oxide, zinc oxide, tantalum oxide, niobium oxide, cerium oxide, zirconium oxide, silicon nitride, silicon oxynitride (SiON), and a mixture thereof is used. preferable. The preferable range of the thickness of the first intermediate layer is 5 nm or more and 100 nm or less, but the lower limit of the above range is more preferably 20 nm, particularly 25 nm, and the upper limit is more preferably 70 nm, particularly 60 nm. The refractive index of the first intermediate layer is preferably 1.7 or more and 2.7 or less.

On the other hand, the second intermediate layers 2 and 32 are preferably formed as low refractive index films having a relatively lower refractive index than the first intermediate layers 1 and 31. The material of the low refractive index film is preferably at least one selected from silicon oxide, aluminum oxide, silicon oxide containing carbon (SiOC), and a mixture thereof. The thickness of the second intermediate layer is 1n
m or more, and preferably 60 nm or less. The refractive index of the second intermediate layer is preferably from 1.4 to 1.8.

The intermediate film uses the light interference effect to suppress light reflection in a wavelength region where the spectral sensitivity characteristics of the photoelectric conversion unit are high. In the present invention, the material constituting the intermediate film, the film thickness of each layer, and the relationship between the layers (when there are multiple layers) are set so that the suppression of reflection greatly contributes to the photoelectric conversion efficiency. On the other hand, since the conventional intermediate film has been simply used as a barrier film or an anti-glossy film, no consideration is given to its relationship with the spectral sensitivity characteristics of the photoelectric conversion unit.

The intermediate film is not limited to the two-layer structure as shown, and may be a single layer or a structure having three or more layers.

As the back electrodes 5, 35, Al, Ag,
At least one selected from Au, Cu, Pt and Cr
It is preferable to form at least one metal layer made of two materials by a sputtering method or an evaporation method. Further, between the photoelectric conversion unit and the metal electrode, ITO, S
A layer made of a conductive oxide such as nO ₂ or ZnO may be formed. In order to obtain a so-called see-through type solar cell, only a conductive oxide having light transmittance as exemplified above may be used.

The transparent substrates 9 and 39 are not particularly limited as long as they are transparent at wavelengths effective for the spectral sensitivity characteristics of the photoelectric conversion unit to be used, but a resin substrate such as plastic or a glass plate is used. . As the transparent substrate, soda lime silica glass (refractive index: about 1.5), which is inexpensive and supplied in large quantities, is preferable. This glass plate is
Manufactured by the float process and has a very smooth surface. The thickness is not particularly limited, but preferably is not more than 0.1.
5 mm or more and 5 mm or less.

For forming the intermediate film and the transparent conductive film, a so-called physical vapor deposition method such as a sputtering method, an ion plating method and a vacuum vapor deposition method may be used. It is preferable to use a so-called chemical vapor deposition method such as a spray method or the like. The physical vapor deposition method is excellent in the uniformity of the film thickness, but the chemical vapor deposition method involving the thermal decomposition oxidation reaction of the raw material is excellent in consideration of the production efficiency in mass production and the durability of the film.

As the spraying method, a solution spraying method in which a solution containing a metal compound is sprayed on a high-temperature glass plate, a dispersion spraying method using a dispersion in which fine particles of a metal compound are dispersed in a liquid instead of the above solution, A powder spray method using a powder of a metal compound instead of the above solution may be used. On the other hand, in the CVD method, steam for forming a film is used.

The spray method has the advantage that it can be carried out with a relatively simple apparatus, but it is difficult to control the droplets and the products to be evacuated (reaction products, undecomposed products, etc.), so that the spray method is uniform. It is difficult to obtain a proper film thickness. Also, the distortion of the glass increases. Therefore, as a method of forming each of the above films, the CVD method is generally superior.

The formation of the intermediate film and the conductive film by the CVD method
It can be performed by cutting into a predetermined size and spraying a gaseous raw material on a heated glass plate. For example,
If the raw material is supplied while the glass plate is placed on a mesh belt and passed through a heating furnace, and the raw material is reacted on the surface of the high-temperature glass plate, an intermediate film or a conductive film can be formed.

However, in the film formation by the CVD method, it is preferable to form a film on a high-temperature glass ribbon in a glass manufacturing process by a float method and use heat energy at the time of glass forming. This preferred production method is advantageous for forming a large-area thin film, and is particularly suitable for the production of a photoelectric conversion unit that also requires film formation on a large-area glass plate for roofing or the like. Further, if the CVD method is performed in a tin float bath space, a film can be formed on a glass surface having a temperature equal to or higher than the softening point, so that the film performance, the film formation reaction speed, and the film formation reaction efficiency can be improved. Further, defects such as pinholes (film loss) are also suppressed.

CV on the glass ribbon in the float method
One embodiment of an apparatus for forming a film by the method D is shown in FIG.
As shown in FIG. 4, in this apparatus, a glass ribbon 10 which flows out of a melting furnace (float kiln) 11 into a tin float bath (float bath) 12 and moves on a tin bath 15 in a strip shape.
A predetermined number of coaters 16 (three coaters 16a, 16b, 16c in the illustrated embodiment) at a predetermined distance from the surface of
Is arranged. The number and arrangement of the coaters are appropriately selected according to the type and thickness of the film to be formed. From these coaters, gaseous raw materials are supplied, and a film is continuously formed on the glass ribbon 10. As described above, if a plurality of coaters are used, an intermediate film and a transparent conductive film can be continuously formed on the glass ribbon 10 by the CVD method. The glass ribbon 10 on which each film is formed is pulled up by the roller 17 and sent to the annealing furnace 13. The glass ribbon that has been gradually cooled in the annealing furnace 13 is cut by a cutting device (not shown) into a glass plate having a predetermined size.

The film formation on the glass ribbon is performed by CVD.
It may be carried out using a combination of the spray method and the spray method. For example, C
By performing the VD method and the spray method in this order (for example, film formation is performed by the CVD method in the tin float tank space, and film formation is performed by the spray method on the downstream side of the tin float tank space in the glass ribbon advancing direction). Then, a predetermined laminated structure may be realized.

As the tin raw material when using the CVD method,
Examples include tin tetrachloride, dimethyltin dichloride, dibutyltin dichloride, tetramethyltin, tetrabutyltin, dioctyltin dichloride, monobutyltin trichloride and the like, and particularly preferred are organic tin chlorides such as dimethyltin dichloride and monobutyltin trichloride. Examples of the oxidizing raw material used to obtain tin oxide from the tin raw material include oxygen, steam, and dry air. Also,
Hydrogen fluoride, trifluoroacetic acid,
Bromotrifluoromethane, chlorodifluoromethane and the like can be mentioned. When antimony is added, antimony pentachloride, antimony trichloride, or the like may be used.

When a silicon oxide film suitable as a low refractive index film is formed by a CVD method, silicon raw materials include monosilane, disilane, trisilane, monochlorosilane, dichlorosilane, 1,2-dimethylsilane, 1,1,1 2-
Examples include trimethyldisilane, 1,1,2,2-tetramethyldisilane, tetramethylorthosilicate, tetraethylorthosilicate, and the like. In this case, examples of the oxidizing material include oxygen, steam, dry air, carbon dioxide, carbon monoxide, nitrogen dioxide, and ozone. When silane is used, an unsaturated hydrocarbon gas such as ethylene, acetylene or toluene may be used in combination for the purpose of preventing the reaction of the silane before reaching the glass surface.

Similarly, when an aluminum oxide film suitable as a low refractive index film is formed by a CVD method, aluminum raw materials include trimethylaluminum, aluminum triisopropoxide, diethylaluminum chloride, aluminum acetylacetonate, and aluminum chloride. No. In this case, examples of the oxidizing material include oxygen, steam, and dry air.

The intermediate film and the transparent conductive film thus formed are laminated on the top surface of the glass plate (the surface formed without contacting tin in the float bath). On these films, various photoelectric conversion layers are formed by a method corresponding to the type, and further, a back electrode is formed by a sputtering method or the like.

[0040]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited by the following examples. (Example 1) A float glass (soda lime silica glass) plate having a thickness of 3 mm, which was cut so as to form a square having a side of 10 cm, was washed and dried. On one surface of this glass plate, a base film and a transparent conductive film were sequentially formed by a CVD method using an open-air transfer furnace. The base film is composed of a high refractive index film and a low refractive index film in order from the glass plate side.
A layer structure was adopted. In addition, the glass plate was conveyed in a furnace using a mesh belt, and heated to about 570 ° C. in the furnace before forming each of the above films. The film forming conditions for each film are shown below.

Formation of Tin Oxide Film (High Refractive Index Film) A mixed gas consisting of monobutyltin trichloride (steam), oxygen and nitrogen is supplied, and a film thickness of 68 n is formed on a glass plate.
m of tin oxide film was formed. Formation of Silicon Oxide Film (Low Refractive Index Film) A mixed gas containing monosilane, ethylene, oxygen and nitrogen was supplied to form a silicon oxide film with a thickness of 3 nm on the tin oxide film. -SnO ₂ : Film formation of F film (transparent conductive film) A mixed gas composed of monobutyltin trichloride (steam), oxygen, nitrogen and hydrogen fluoride (steam) is supplied, and the film thickness is 200 nm on the silicon oxide film. Of a SnO ₂ : F film was formed. Table 1 shows the composition of the mixed gas used for forming each film.
Shown in

(Table 1) ―――――――――――――――――――――――――――― Type of film Composition of mixed gas (volume ratio) N ₂ / O ₂ / HF / Sn / Si / C ₂ H ₄ ―――――――――――――――――――――――――― Tin oxide film 640 100 0 silicon oxide film 200 4 00 16 SnO ₂ : F film 6 410 0 0 ――――――――――――――――――――――――――― --- In Table 1, monobutyltin chloride is abbreviated as Sn and monosilane is abbreviated as Si.

Example 2 The thickness of the tin oxide film (high refractive index film) was 31 nm, and the thickness of the silicon oxide film (low refractive index film) was 7 n.
An intermediate film having the two-layer structure and a SnO ₂ : F film (thickness: 200 nm) were formed on a glass plate in the same manner as in Example 1 except that m was used.

Comparative Example 1 A SnO ₂ : F film (200 nm thick) was formed directly on a glass plate in the same manner as in Example 1 except that the formation of two intermediate films was omitted. Filmed.

Comparative Example 2 A silicon oxide film (thickness: 30 nm) was formed on a glass plate in the same manner as in Example 1 except that the formation of the tin oxide film (high refractive index film) was omitted. And SnO
₂ : F films (thickness: 200 nm) were sequentially formed.

Comparative Example 3 The thickness of the tin oxide film (high refractive index film) was 18 nm, and the thickness of the silicon oxide film (low refractive index film) was 28
An intermediate film having the above two-layer structure and a SnO ₂ : F film (thickness: 200 nm) were formed on a glass plate in the same manner as in Example 1 except that the thickness was changed to nm.

With respect to the glass plate with a transparent conductive film obtained as described above, the spectral reflectance was measured in accordance with JIS R3106-1998, with the surface of the glass plate opposite to the surface on which each film was formed as the incident side. Table 2 shows the values of the average reflectance of each glass plate with a transparent conductive film in the wavelength range of 450 to 550 nm.

[0048]

The wavelength of 450 to 550 nm corresponds to a wavelength range of 500 nm ± 50 nm at which the spectral sensitivity of the amorphous silicon becomes maximum.

Table 3 shows the values of the average reflectance in the wavelength range of 450 to 550 nm and in the wavelength range of 700 to 800 nm for the glass plates with a transparent conductive film of Example 2 and Comparative Examples.

(Table 3) Average reflectance (%) 450 to 550 nm 700 to 800 nm ――――――――――――――――――――――――――――― Example 2 13.57 7.91 ―――――――――― ――――――――――――――――――――― Comparative Example 1 17.41 8.18 Comparative Example 2 17.91 8.38 Comparative Example 3 14.25 8.54 ― ―――――――――――――――――――――――――――――

The wavelength of 700 to 800 nm corresponds to a range of 750 nm ± 50 nm at which the spectral sensitivity of the crystalline silicon becomes maximum.

In Examples 1 and 2, the wavelengths of 450 to 55
The reflectance at 0 nm is 80% or less as compared with the case where no intermediate film is formed (Comparative Example 1) (improvement of about 7 points). Therefore, the film configurations described in Embodiments 1 and 2 are suitable when an amorphous silicon material is used as the photoelectric conversion layer. Further, in Example 2, the wavelength was 450 to 550 n compared to the case where the intermediate film was not formed (Comparative Example 1).
m and the wavelengths of 700 to 800 nm, the reflectance decreases (about 4 points in both wavelength ranges,
About 0.3 point improvement). Therefore, the film configuration described in Example 2 is suitable for a case where both a photoelectric conversion layer containing an amorphous silicon material and a photoelectric conversion layer containing a crystalline silicon material are used.

The thickness applied in Comparative Example 2 corresponds to the thickness of the silicon oxide film formed as the barrier film. The film thickness applied in Comparative Example 3 corresponds to the film thickness proposed in Japanese Patent Publication No. 3-72586 in order to eliminate the glitter of the transparent conductive film. In these conventional interlayer films, the reflectance cannot be reduced in the wavelength range where the sensitivity of the photoelectric conversion unit is high to the extent of Examples 1 and 2.

(Examples 3 to 5) Further, a glass plate with a transparent conductive film was produced by using the above-described apparatus for forming a film on a glass ribbon. A mixed gas composed of dimethyltin dichloride (DMT), oxygen, helium, and nitrogen was supplied from a coater located on the most upstream side. A mixed gas consisting of monosilane, ethylene, oxygen, and nitrogen was supplied from a coater on the downstream side. Subsequently, a mixed gas comprising dimethyltin dichloride, oxygen, steam, nitrogen, and hydrogen fluoride was supplied from a coater further downstream. In this way, a tin oxide film, a silicon oxide film,
A fluorine-containing tin oxide film (SnO ₂ : F film) was laminated in this order and cut to obtain a glass plate with a transparent conductive film.

(Comparative Examples 4 to 6) In Examples 3 and 5, the same mixed gas as described above was supplied only from the coater to which the mixed gas for forming the silicon oxide film and the SnO ₂ : F film was supplied. A glass plate with a transparent conductive film was obtained in which the same silicon oxide film and SnO ₂ : F film as in each example were formed in this order on a glass plate. However, the thickness of the silicon oxide film is all 3
It was set to 0 nm.

With respect to the glass plates with transparent conductive films obtained from Examples 3 to 5 and Comparative Examples 4 to 6, the average reflectance in the same wavelength range as described above was measured. Table 4 shows the measurement results of the average reflectance along with the thickness of each film.

(Table 4) Film formation on glass ribbon ―――――――――――――――――――――――――――――――― Tin oxide Silicon oxide SnO ₂ : F film Average reflectance (%) Film thickness (nm) Film thickness (nm) Film thickness (nm) 450 to 550 nm 700 to 800 nm ―――――――――――――――― ―――――――――――――――――― Example 3 45 15 460 9.84 10.31 Comparative Example 4 -30 460 14.3 10.87 ―――――――― ―――――――――――――――――――――――――― Example 4 29 33 600 9.21 10.95 Comparative Example 5-30 600 13.9 11.32 ―――――――――――――――――――――――――――――――――― Example 5 20 35 790 8.71 11.84 Comparative Example 6 − 30 790 8.78 11.97 ――――― ----------------------------

Also in Examples 3 to 5, the average reflectance in both the wavelength ranges was lower than that in the case where the undercoating film made of a 30-nm-thick silicon oxide film was formed. in this way,
According to the present invention, in which the sensitivity of the photoelectric conversion unit is improved in the wavelength range where the sensitivity of the photoelectric conversion unit is large by using the antireflection effect of the intermediate film, the light is transmitted to the photoelectric conversion unit without impairing the conductivity of the transparent conductive film. Incident can be increased.
In the present invention, as long as the refractive index of the intermediate film, the number of layers, and the film thickness are designed so as to obtain the antireflection effect described above,
The specific configuration of the intermediate film is not limited to the above example. In addition,
In each of the above embodiments, the optical characteristics were measured by omitting the photoelectric conversion unit. However, even if the photoelectric conversion unit was formed on each transparent conductive film, if the configuration and thickness of the photoelectric conversion unit were the same, a glass plate was used. It has been confirmed that the reflectance ratio of light rays incident from the side is not substantially affected.

Example 6 A thin film photoelectric conversion device comprising an amorphous silicon photoelectric conversion unit was formed on the glass plate with a transparent conductive film of Example 2 by a plasma CVD method. In the pin junction included in the amorphous silicon photoelectric conversion unit, the thickness of the p-type amorphous silicon carbide layer used was 15 nm, and the thickness of the n-type amorphous silicon layer was 30 nm. The intrinsic amorphous silicon layer (i-type) was formed by an RF plasma CVD method. The film forming conditions include a reaction gas of silane, a pressure in a reaction chamber of about 40 Pa, and 15 mW / c.
An RF power density of m ² and a deposition temperature of 150 ° C. were used. The dark conductivity of the intrinsic amorphous silicon film deposited directly to a thickness of 300 nm on the glass substrate under the same conditions as the film formation conditions was 5 × 10 ⁻¹⁰ S / cm. Note that the thickness of the intrinsic amorphous silicon layer was 300 nm.
Finally, an 80-nm-thick ITO film and a 300-nm-thick Ag film were deposited by sputtering in this order as a back electrode.

The light of AM 1.5 was incident on the thin film photoelectric conversion device (photoelectric conversion area 1 cm ² ) thus produced as incident light.
The output characteristics when irradiated with a light amount of 00 mW / cm ² were measured. As a result, the open-circuit voltage was 0.89 V, the short-circuit current density was 16.4 mW / cm ² , the fill factor was 72.0%,
And the conversion efficiency was 10.5%. Further, when a light deterioration test was performed by irradiating AM1.5 light at 48 ° C. with a light amount of 100 mW / cm ² , the conversion efficiency was reduced to 8.7% after irradiation for 550 hours.

[0062]

As described above, according to the present invention,
By disposing an intermediate film that reduces the reflectance of light incident from the transparent substrate side between the transparent substrate and the transparent conductive film,
It is possible to provide a photoelectric conversion device in which the ratio of light beams used for photoelectric conversion is improved and the photoelectric conversion efficiency is improved.

[Brief description of the drawings]

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

FIG. 2 is a cross-sectional view of another embodiment of the photoelectric conversion device of the present invention.

FIG. 3 is a diagram showing spectral sensitivity characteristics of amorphous silicon and crystalline silicon.

FIG. 4 is a diagram showing a configuration of a device which can be used for forming an intermediate film and a transparent conductive film on a glass plate as a part of the photoelectric conversion device of the present invention.

[Explanation of symbols]

 Reference Signs List 1, 31 First intermediate film (high refractive index film) 2, 32 Second intermediate film (low refractive index film) 3, 33 Transparent conductive film 4 Photoelectric conversion unit 5 Back electrode 9 Transparent substrate 10 Glass ribbon 11 Melting furnace DESCRIPTION OF SYMBOLS 12 Float bath (tin float tank) 13 Slow-cooling furnace 16 Coater 17 Roller 21 Spectral sensitivity curve of amorphous silicon 22 Spectral sensitivity curve of crystalline silicon 30 Substrate for photoelectric conversion device 35 Backside electrode 37 (First) photoelectric conversion unit 38 (Second) photoelectric conversion unit 39 glass plate

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Akira Fujisawa, 3-5-11 Doshomachi, Chuo-ku, Osaka-shi, Osaka Prefecture Inside Nippon Sheet Glass Co., Ltd. (72) Yukio Sueyoshi 3-chome, Doshucho, Chuo-ku, Osaka-shi, Osaka No. 5-11 F-term in Nippon Sheet Glass Co., Ltd. (reference) 5F051 AA03 AA04 AA05 CA02 CA03 CA04 CA15 DA04 DA15 FA03 FA04 HA03 HA06

Claims (7)

[Claims] 1. A transparent substrate, and
A transparent conductive film, a photoelectric conversion unit including a photoelectric conversion layer, and
A photoelectric conversion device having a back electrode laminated thereon, wherein an intermediate film is further provided between the transparent substrate and the transparent conductive film.
Of the light beam, wherein the spectral sensitivity characteristic of the photoelectric conversion layer is maximized.
When the wavelength is λ [nm], (λ−50) nm or more (λ +
50) Average reflectance R in a wavelength region of nm or less ₁And before
Average in the wavelength range in the state where the intermediate film is not formed
Reflectivity R_TwoAnd R₁<R_Two× 0.8
Characteristic photoelectric conversion device. 2. A transparent substrate, and
A transparent conductive film, two or more photoelectric conversion units and a back electrode are laminated, and the two or more photoelectric conversion units include two photoelectric conversion layers having different wavelengths λ of the light beams at which spectral sensitivity characteristics are maximized. A photoelectric conversion device, wherein an intermediate film is further formed between the transparent substrate and the transparent conductive film, and the wavelengths λ in the two photoelectric conversion layers are respectively set to λ.
₁ [nm], as λ ₂ [nm], the in a state that does not form an average reflectance R _11, the intermediate layer in the (lambda ₁ -50) nm or more (lambda ₁ +50) nm or less in the first wavelength band First
And the average reflectance R ₁₂ is an R ₁₁ <meet R _12, and (lambda ₂ -50) nm or more (lambda ₂ +50) average reflectance R ₂₁ in the second wavelength region nm or less in the wavelength range, the intermediate layer Wherein the average reflectance R ₂₂ in the second wavelength range in a state where no is formed satisfies R ₂₁ <R ₂₂ . 3. The photoelectric conversion device according to claim 2, wherein the two photoelectric conversion layers having different wavelengths λ include at least one selected from an amorphous silicon-based photoelectric conversion layer and a crystalline silicon-based photoelectric conversion layer. apparatus. 4. The photoelectric conversion device according to claim 1, wherein the intermediate film comprises two layers of a high refractive index film and a low refractive index film in order from the transparent substrate side. 5. The high refractive index film has a refractive index of 1.7 or more and 2.7.
5. The photoelectric conversion device according to claim 4, wherein the low refractive index film has a refractive index of 1.4 or more and 1.8 or less. 6. 6. The photoelectric conversion device according to claim 4, wherein the high refractive index film has a thickness of 20 nm or more. 7. The photoelectric conversion device according to claim 1, wherein the intermediate film includes a layer containing silicon oxide as a main component.