JPH11298021A - Substrate for photovoltaic element, photovoltaic element using the same, integrated photovoltaic element, and method of manufacturing integrated photovoltaic element - Google Patents

Abstract

(57) [Problem] To provide a photovoltaic element which does not deteriorate its function even when a reverse bias is applied in a high humidity environment, while using a metal having a high reflectivity in a visible light region as a back reflection layer. provide. SOLUTION: A transparent conductive layer 205, a semiconductor layer 206, a transparent electrode layer 207, and a current collecting electrode 208 are sequentially stacked on a substrate in which a light reflection layer 202 and a transparent insulating layer 203 are sequentially stacked on a support 201. A photovoltaic element characterized by comprising:

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a photovoltaic device, and more particularly to a photovoltaic device made of a silicon-based non-single-crystal semiconductor material.

[0002]

2. Description of the Related Art At least one p-i-layer made of a non-single-crystal silicon material such as an amorphous Si solar cell.
The back reflection layer of a photovoltaic element such as a solar cell having a semiconductor layer having an n-junction uses a metal having a high reflectance in the visible light region, such as Ag, Cu, or Al, to improve the photoelectric conversion efficiency. Improvements have been implemented. But A
Metals having high reflectivity in the visible light region, such as g and Cu, are known as metals that cause a migration phenomenon in the presence of moisture and an electric field. When the migration phenomenon occurs, metal dendrite is generated, and finally, the metal is connected to the counter electrode, and a short circuit occurs.

[0003] In order to suppress the intrusion of moisture into the solar cell, the light receiving surface is usually sealed with a fluororesin or the like, but the intrusion of moisture can be completely prevented. Absent. In addition, if the light receiving surface is sealed with glass or the like, it is possible to completely prevent intrusion of moisture, but the weight of the solar cell module becomes heavy and handling becomes difficult, which is not preferable.

[0004] In addition, studies have been conducted to suppress the migration of Ag, Cu and the like. The relationship between the Pd concentration and the migration resistance of the Pd alloy was investigated, and the migration mechanism of the Ag-based metal was considered.

[0005] Further, "Brightening Technology Research Journal Vol. 30,
page. 124-130, 1991, "The Ch
arcartistics of Electroc
chemical / Migration / in / Copp
er-Base Alloy. In "Tomio Higashie, Masahiro Tsuji, Hidehiko Mune", we investigated the types and amounts of alloying elements with regard to the migration resistance of copper alloys to improve the reliability of electrical equipment. As a result, Si was the most remarkable. The effect of improving the resilience is recognized, and when Zn is added, the effect is 29.4 at%.
It has been reported that the aging treatment is further improved by adding i.

Thus, Ag, Cu, In, Sn, P
When d or the like is added, or when Ni or Si is added to Cu, migration can be suppressed to some extent, but in any case, the reflectance in the visible light region can be reduced by adding another metal. Will drop. Therefore, when comprehensively judged, a thin film layer made of a material containing aluminum as a main component is advantageous as the back reflection layer.

On the other hand, when a transparent conductive layer made of zinc oxide is formed by a sputtering method, it is formed at a relatively high temperature,
There is known a technique for improving the light collection efficiency by making the surface shape have an uneven structure (texture structure).

For example, see “Y. Hamagawa, et.
al, Appl. Phys. Lett. , 43 (198
3) In p644 ″, by interposing a transparent conductive layer of TiO ₂ between the back electrode of Ag and the semiconductor layer of amorphous silicon, the spectral sensitivity of the solar cell in the long wavelength region is increased. Have been reported.
Also, “T. Tiedje, et. Al, Proc.
6th ・ IEEE ・ Photovoltaic ・ Spe
cialist Conf. (1982) p1423 "
And "H. Deckman, et. Al, Pro.
c. 16th ・ IEEE ・ Photovoltaic ・
Specialist Conf. (1982) p14
In the case of 25 ", the shape of the back electrode is made uneven (texture structure) having a size approximately equal to the wavelength of light that scatters light, so that long-wavelength light that cannot be completely absorbed by the semiconductor layer is scattered. A technique has been disclosed in which the optical path length in a photovoltaic device is extended, the long-wavelength sensitivity of the photovoltaic element is improved, the short-circuit photocurrent is increased, and the photoelectric conversion efficiency is improved.

[0009] Zinc oxide has higher resistance to plasma than tin oxide and indium oxide, and is not reduced by hydrogen even when exposed to plasma containing hydrogen. When a semiconductor layer made of amorphous silicon is formed thereon by a plasma CVD method, zinc oxide is actively used as a transparent conductive layer.

[0010]

Conventionally, a photovoltaic element made of a non-single-crystal silicon-based material has a low photoelectric conversion efficiency, and is difficult to apply to photovoltaic power generation such as a solar cell. there were.

Therefore, a metal having high reflectivity in the visible light region, such as Cu and Ag, is used for the back surface reflection layer to improve the photoelectric conversion efficiency. However, since a non-single-crystal silicon-based semiconductor containing hydrogen is usually used in a thickness of several microns or less, it is at most 0.4 (V) to 0.8 (V).
An electric field of about several thousand (V / cm) is applied to the semiconductor layer even with a reverse bias of the order. Therefore, if the photovoltaic element is exposed to a state where a reverse bias is applied to the element for a long time, such as a partial shade state, in an environment with a relatively high humidity, metals such as Ag and Cu cause migration, and the element is short-circuited. Have done
There is a problem that the function of the element is reduced.

Further, as described above, Ag, Cu, In,
Add Sn, Pd, etc., or add Mg, Ni, Si
In some cases, the addition of other metals can suppress migration, but in any case, the addition of another metal decreases the reflectance in the visible light region, and lowers the photoelectric conversion efficiency. There was a problem.

Al is a metal having a high reflectance instead of Ag and Cu. However, in order to form a zinc oxide thin film having a texture structure with high light collection efficiency on Al, it is necessary to increase the thickness of the thin film (3 μm).
m) ”or“ When performing the sputtering method, A
a mixed gas of r and H ₂ O ”. However, in the former case, the problem of "increase the cost" of the photovoltaic element is caused. In the latter case, the deposition rate is reduced and the reflectance (the composition of zinc oxide thin film / aluminum) is reduced. There has been a problem that the conductive properties, especially the fill factor, are reduced.

An object of the present invention is to solve the above-mentioned problems and to provide a high-quality photovoltaic element. That is, it is an object of the present invention to provide a photovoltaic element in which the function of the element does not deteriorate even when a reverse bias is applied in a high humidity environment while using a metal having a high reflectance in the visible light region as a back reflection layer. . It is another object of the present invention to provide a solar cell that is lightweight, flexible, generates stable power for a long period of time, and has a low power cost. In addition, the purpose is to install solar cells on the roof of a house to carry out solar power generation, and to function as night lighting, guide lights, and ventilation equipment in public facilities such as parks and road signs.

[0015]

Means for solving the above problems are as follows: (1) A photovoltaic device characterized in that a light reflecting layer and a transparent insulating layer are sequentially laminated on a support. A power element substrate and a photovoltaic element using the substrate.

In a conventional photovoltaic device using a substrate in which a transparent conductive layer is directly laminated on a light reflecting layer, Ag used as a light reflecting layer is applied by applying a reverse bias under a high temperature and high humidity environment. Since Cu and the like cause migration, the photoelectric characteristics of the photovoltaic element have been reduced. Therefore, a metal such as Al that does not cause migration is used as the light reflection layer, but the light reflectance is lower than that of Ag and Cu, and the photoelectric characteristics are deteriorated.

However, in the present invention, a reverse bias is not applied to the light reflecting layer by providing the transparent insulating layer between the light reflecting layer and the transparent conductive layer, and the light reflecting layer has a high reflectance of Ag, Cu or the like. Can now use a tired metal as a migration-inducing metal.

Further, by using the substrate for a photovoltaic element of the present invention, the uniformity of the transparent conductive layer is improved. When the surface of a single layer of zinc oxide (transparent conductive layer) formed on an aluminum thin film (light reflecting layer) is carefully observed with an electron microscope, a pinhole having a diameter of about 1000 mm may be generated. However, it was found that the transparent conductive layer formed on the substrate for a photovoltaic element of the present invention had a pinhole generation rate of 5% or less of the single layer. By reducing the number of pinholes in the transparent conductive layer, the yield of the photovoltaic element can be significantly improved. Further, since the leak current is small, the open-circuit voltage is high.

(2) A substrate for a photovoltaic element, further comprising a second current collecting electrode on the transparent insulating layer, and a photovoltaic element using the substrate.

By providing the second current collecting electrode, the current collecting capacity can be increased and the photoelectric conversion efficiency can be improved.

(3) The transparent insulating layer comprises at least one of aluminum oxide, magnesium fluoride, silicon oxide, silicon nitride, titanium oxide, zinc sulfide, cesium fluoride, zirconium oxide, or a composite oxide thereof. A substrate for a photovoltaic element and a photovoltaic element using the substrate.

For this reason, wavelengths of 300 nm or more and 1000
It has high sensitivity to ultraviolet light, visible light and infrared light of nm or less. Further, the transparent insulating layer can prevent water, which is one of the causes of migration, from entering the light reflecting layer.

(4) The transparent conductive layer comprises at least one of indium oxide, tin oxide, indium tin oxide, zinc oxide, cadmium oxide, cadmium tin oxide, bismuth oxide, molybdenum oxide or a composite oxide thereof. Is a photovoltaic element characterized by the following.

For this reason, wavelengths of 300 nm or more and 1000
It has high sensitivity to ultraviolet light, visible light and infrared light of nm or less.

(5) A plurality of photovoltaic elements comprising a transparent conductive layer, a semiconductor layer, a transparent electrode layer, and a collecting electrode sequentially laminated on the photovoltaic element substrate. Stacking a transparent conductive layer, a semiconductor layer, a transparent electrode layer, and a collecting electrode on the integrated photovoltaic device and the substrate for the photovoltaic device, and dividing the photovoltaic device into a plurality of photovoltaic devices by a laser. And a method of manufacturing an integrated photovoltaic device.

By integration, a high voltage and a high current can be obtained, and power loss due to the resistance of the transparent electrode layer can be suppressed.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic sectional view showing an example of the substrate for a photovoltaic element of the present invention. The substrate for a photovoltaic element of the present invention comprises a support 101, a light reflecting layer 102, a transparent insulating layer 10.
3 are sequentially laminated. In FIG. 1, a transparent conductive layer 105 is laminated thereon.

(Support 101) The support may be any type of conductive material or insulating material. Examples of the conductive material include a plated steel sheet, NiCr, stainless steel, Al, Cr,
Mo, Au, Nb, Ta, V, Ti, Pt, Pb, Sn
Metals such as, or their alloys, and insulating materials include polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, and other synthetic resins, or glass, ceramics, paper, etc. Is mentioned.

The surface shape of the support is smooth or irregularities having a peak height of at most 0.1 to 1.0 μm (texture).
Desirably. For example, as one method of texturing the surface of a stainless steel substrate, there is an etching treatment on a substrate to be processed using an acidic solution.

The thickness of the support is appropriately determined so that a desired photovoltaic element can be formed. However, when flexibility as the photovoltaic element is required, the function as the support is sufficiently exhibited. As thin as possible.
However, the thickness is usually 10 μm from the viewpoint of mechanical strength in production and handling of the support.

(Light Reflecting Layer 102) A light reflecting layer is formed on at least one surface of the support 101. The light reflecting layer is
For example, a metal having a high reflectance from visible light to near infrared, such as Au, Ag, Al, Cu, AlSi, and CuMg, is used.
Of these, gold, silver, copper, or aluminum,
Alternatively, alloys containing these metals as main components are preferable.

The light reflecting layer is suitably formed by an electrolytic deposition method from an aqueous solution such as a vacuum evaporation method and a sputtering method. The layer thickness of these metals as a light reflecting layer is 10
A suitable layer thickness is from nm to 5000 nm.

(Transparent insulating layer 103) On the light reflecting layer 102, Al ₂ O ₃ , MgF ₂ , SiO ₂ , Si ₃ N ₄ , TiO ₂ , Z
A transparent insulating layer made of nS, CeF ₃ , ZrO ₂ or the like is formed.

As a method for forming the transparent insulating layer, a vacuum deposition method, a sputtering method, an electrolytic deposition method, a CVD method, a spray method, a spin-on method, a dipping method and the like are mentioned as suitable methods. Although the optimum layer thickness varies depending on the refractive index of the layer, a preferable range of the layer thickness is 50.
nm to 10 μm. Further, in order to texture the transparent insulating layer, for example, in a sputtering method, the formation temperature of the layer may be set to 200 ° C. or higher.

Next, the photovoltaic device of the present invention will be described.

FIG. 2 is a schematic sectional view showing an example of the photovoltaic device of the present invention. In FIG. 2, a transparent conductive layer 205, a semiconductor layer 206, a transparent electrode layer 207, a transparent conductive layer 205, a transparent electrode layer 207, and a support 201, a light reflecting layer 202, and a transparent insulating layer 203 are formed on a substrate.
The collecting electrode 208 is stacked.

(Transparent conductive layer 205) The transparent conductive layer is formed on the transparent insulating layer 203 of the substrate.

As the transparent conductive layer, for example, ZnO, Sn
O ₂ , In ₂ O ₃ , ITO, CdO, Cd ₂ SnO ₄ , Bi ₂
O ₃ , MoO ₃ , Na _x WO _{3 and the} like can be mentioned.

Suitable methods for forming the transparent conductive layer include vacuum deposition, sputtering, electrolytic deposition, CVD, spraying, spin-on, and dipping. Although the optimum layer thickness varies depending on the refractive index of the layer, a preferable range of the layer thickness is 50.
nm to 10 μm.

Further, in order to texture the transparent conductive layer, for example, in a sputtering method, the formation temperature of the layer may be set to 200 ° C. or higher. In any of the formation methods, etching the surface with a weak acid or weak alkali after the formation of the layer is also effective in enhancing the texture effect.

(Semiconductor Layer 206) The semiconductor layer is not particularly limited, but at least one of a non-single-crystal n-type layer or a p-type layer containing silicon atoms, a non-single-crystal i-type layer, and a non-single-crystal p formed by laminating a p-type layer or an n-type layer
Preferably, it has an in structure.

<Doping Layer (n-layer, p-layer)> The base material of the doping layer is composed of an amorphous silicon-based or microcrystalline silicon-based semiconductor. As amorphous (abbreviated as a-) silicon-based semiconductor, a-si, a-SiC, a-
SiO, a-SiN, a-SiCO, a-SiON, a
-SiNC, a-SiCON and the like. The base material may be an amorphous silicon-based semiconductor containing microcrystalline silicon.

The amount of the valence electron controlling agent introduced to make the conductivity type p-type or n-type is 1000 ppm to 10 ppm.
% Is mentioned as a preferable range. Hydrogen (H, D) and fluorine work to compensate for dangling bonds and improve doping efficiency. The optimum value of the hydrogen and fluorine content is 0.1 to 30 at%. Especially when the doping layer contains microcrystalline silicon,
-10 atm% is mentioned as the optimum amount. The suitable amount of carbon, oxygen and nitrogen atoms to be introduced is 0.1 ppm to 20%.

As for the electrical characteristics, those having an activation energy of 0.2 eV or less are preferable, and the specific resistance is 1 eV.
It is preferably at most 00 Ωcm, most preferably at most 1 Ωcm.

<I-layer> The i-layer is the most important layer for generating and transporting photoexcited carriers. Preferably, microcrystalline silicon is used. Microcrystalline silicon is formed by a high-frequency plasma CVD method in the range of 13.56 MHz to 2.45 GHz, and the photon energy dependence of the extinction coefficient is close to that of amorphous silicon on the high energy side and low on the low energy side. And is close to crystalline silicon. It is preferable that the i-layer is composed of a plurality of types of microcrystalline silicon having substantially different average grain sizes in the thickness direction.

As for the method for forming the i-layer, the formation temperature is preferably in the range of 200 to 500 ° C. The forming pressure is preferably in the range of 10 to 100 mTorr. Further, a high frequency in the range of 100 to 2.45 GHz and a high frequency of 13.56 MHz are superimposed, and the applied power density is respectively 0.01 to 1.0 W / c.
m ³ , preferably in the range of 0.001 to 0.1 W / cm ³ .

(Transparent electrode layer 207) Indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), ITO (In ₂
O ₃ —SnO ₃ ) is a suitable material, and these materials may contain fluorine. For the deposition of the transparent electrode layer, a sputtering method or a vacuum evaporation method is the most suitable deposition method.

When depositing by a sputtering method, a target such as a metal target or an oxide target is appropriately used in combination. When depositing by the sputtering method, the substrate temperature is an important factor.
00 ° C. is mentioned as a preferable temperature range. In addition, as a gas for sputtering when the transparent electrode layer is deposited by a sputtering method, an inert gas such as an argon gas (Ar) can be given. It is also preferable to add oxygen gas (O ₂ ) to the inert gas as needed. Particularly when a metal is targeted, oxygen gas (O ₂ ) is essential. Further, when the target is sputtered by the inert gas or the like, the pressure in the discharge space is 0.1 to 50 m in order to effectively perform sputtering.
Torr is mentioned as a preferable range. The deposition rate of the transparent electrode layer depends on the pressure in the discharge space and the discharge pressure,
The optimum deposition rate is 0.01 to 10 nm / sec.
Range.

As a deposition source suitable for depositing the transparent electrode layer in the vacuum deposition method, there are metal tin, metal indium tin, indium-tin alloy and the like. The substrate temperature for depositing the transparent electrode layer is 25 ° C. to 600 ° C.
The range of ° C. is a suitable range. Further, oxygen gas (O ₂ ) is introduced, and the pressure is 5 × 10 ⁻⁵ Torr to 9 × 1.
It is preferable to deposit in the range of 0 ^-4 Torr. By introducing oxygen in this range, the metal vaporized from the evaporation source reacts with oxygen in the gas phase to deposit a good transparent electrode. The preferable range of the deposition rate of the transparent electrode layer under the above conditions is 0.01 to 10 nm / sec.
When the deposition rate is less than 0.01 nm / sec, the productivity is reduced, and when the deposition rate is more than 10 nm / sec, the film becomes coarse, which is not preferable from the viewpoint of transmittance, conductivity and adhesion.

It is preferable that the thickness of the transparent electrode layer is deposited so as to satisfy the conditions of the antireflection film.
As a specific layer thickness, a preferable range is 50 to 500 nm.

(Current Collector Electrode 208) In order to make more light incident on the i-layer, which is a photovoltaic layer, and to efficiently collect generated carriers at the electrode, the shape of the current collector electrode (as viewed from the light incident direction). Shape) and material are important. Usually, the shape of the collecting electrode is a comb shape, and the line width, the number of lines, and the like are determined by the shape and size of the photovoltaic element viewed from the light incident direction, the material of the collecting electrode, and the like. Line width is usually 0.1
mm to about 5 mm.

The material of the collecting electrode may be Fe, Cr, N
i, Au, Ti, Pd, Ag, Al, Cu, AlSi,
C (graphite) or the like is used, and usually, a metal such as Ag, Cu, Al, Cr, or C having a small specific resistance, or an alloy thereof is suitable. The layer structure of the collecting electrode may be composed of a single layer, or may be composed of a plurality of layers. These metals are preferably formed by a vacuum deposition method, a sputtering method, a plating method, a printing method, or the like. 10 nm to 0.5 m as layer thickness
m is suitable.

In the case of forming by a vacuum deposition method, a mask having a shape of a collecting electrode is brought into close contact with the transparent electrode layer 207, and a desired metal deposition source is evaporated in a vacuum with an electron beam or resistance heating. A collector electrode having a desired shape is formed thereon. When formed by a sputtering method, a mask having a shape of a collecting electrode is closely attached to the transparent electrode layer 207, an Ar gas is introduced into a vacuum, DC is applied to a desired metal sputtering target, and a glow discharge is generated. Thereby, the metal is sputtered and the transparent electrode layer 20
On 7, a collecting electrode having a desired shape is formed.

When forming by a printing method, an Ag paste, an Al paste, or a carbon paste is printed by a screen printing machine.

FIG. 3 is a schematic sectional view showing another example of the photovoltaic element of the present invention, which differs from FIG. 2 in that a second current collecting electrode 304 is provided on a transparent insulating layer 303.

(Second current collecting electrode 304) In order to allow more light to enter the i-layer, which is a photovoltaic layer, and to efficiently collect generated carriers at the electrode, the shape of the current collecting electrode (light incidence) The shape viewed from the direction) and the material are important. Usually, the shape of the collecting electrode is a comb shape, and its line width, number of lines, etc.
Shape and size of the photovoltaic element viewed from the light incident direction,
It is determined by the material of the collecting electrode and the like. Line width is usually
It is about 0.1 mm to 5 mm.

The material of the current collecting electrode is Fe, Cr, N
i, Au, Ti, Pd, Ag, Al, Cu, AlSi,
C (graphite) or the like is used, and usually, a metal such as Ag, Cu, Al, Cr, or C having a small specific resistance, or an alloy thereof is suitable. The layer structure of the collecting electrode may be composed of a single layer, or may be composed of a plurality of layers. These metals are preferably formed by a vacuum deposition method, a sputtering method, a plating method, a printing method, or the like. 10 nm to 0.5 m as layer thickness
m is suitable.

In the case of forming by a vacuum evaporation method, a mask having a shape of a collecting electrode is closely adhered onto the transparent insulating layer 303, and a desired metal evaporation source is evaporated in a vacuum with an electron beam or resistance heating to form a transparent insulating layer. A current collecting electrode having a desired shape is formed on 303. In the case of forming by a sputtering method, a mask having a shape of a collecting electrode is closely attached to the transparent insulating layer 303, an Ar gas is introduced into a vacuum, DC is applied to a desired metal sputtering target, and a glow discharge is generated. Thereby, metal is sputtered, and the transparent insulating layer 30
A collector electrode having a desired shape is formed on 3.

When forming by a printing method, an Ag paste, an Al paste, or a carbon paste is printed by a screen printing machine.

Next, the integrated photovoltaic device of the present invention will be described.

FIG. 4 is a schematic sectional view showing an example of the integrated photovoltaic device of the present invention.
02, a plurality of photoelectric conversion regions in which a transparent conductive layer 405, a semiconductor layer 406, a transparent electrode layer 407, and a collecting electrode 408 are stacked over a substrate formed of a transparent insulating layer 403. Then, the transparent conductive layer 405 of one photovoltaic element (collecting electrode 4
08) and the transparent electrode layer 407 of another photovoltaic element are connected in series. The connection method of the photovoltaic element is not particularly limited, and the transparent conductive layers 405 and the transparent electrode layers 407 of the photovoltaic element may be connected in parallel.

The method of manufacturing the integrated photovoltaic element is not particularly limited, but the transparent conductive layer 405 and the semiconductor layer 4
06, the transparent electrode layer 407, and the current collecting electrode 408, and then a laser is used to divide the photovoltaic elements into a plurality of photovoltaic elements.

The laser used to divide the photoelectric conversion region on the transparent insulating layer 403 into small-area photovoltaic elements is:
A YAG laser, a CO ₂ laser, an excimer laser, or the like can be used, but a YAG laser is particularly preferably used. In addition to the fundamental wavelength of 1.06 μm, light of 0.53 μm of the second harmonic obtained by using a nonlinear optical element together can also be used. The YAG laser can perform a continuous transmission operation, but is often used in a Q-switch pulse transmission operation to obtain a high peak power. The frequency of Q switch pulse transmission is usually about several kHz to several tens kHz, and the duration of one pulse is about 100 nsec.

[0065]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below by taking a solar cell as an example of a photovoltaic element, but the present invention is not limited to this.

Example 1 A substrate for a photovoltaic element shown in FIG. 1 was manufactured by the following procedure.

5 × 5 cm ² SU as the support 101
On the S304 substrate, Ag was deposited as the light reflecting layer 102 by 8000 ° by sputtering, aluminum oxide was deposited by vacuum deposition as the transparent insulating layer 103, aluminum oxide was 1 μm, and indium tin oxide and zinc oxide were deposited as the transparent conductive layer 105 by 200 °, 1 μm by sputtering. Was.

Comparative Example 1 A substrate for a photovoltaic element shown in FIG. 6 was manufactured in the following procedure.

5 × 5 cm ² SU as the support 601
Ag was deposited on the S304 substrate as the light reflection layer 602 by sputtering at 8000 ° and zinc oxide as the transparent conductive layer 605 was deposited by sputtering at 1 μm.

The substrates of Example 1 and Comparative Example 1 were measured for direct reflection and diffuse reflection. Table 1 shows the results. The result is a value when the reflection of 800 nm wavelength Ag is set to 100.

[0071]

[Table 1]

The direct reflection of the substrate of Example 1 can obtain a good value, and is equivalent to that of Comparative Example 1. In Example 1, the irregular reflection showed better results.

Example 2 A photovoltaic element shown in FIG. 2 was manufactured in the following procedure.

5 × 5 cm ² SU as support 201
S304: Ag on the substrate as the light reflection layer 202, 5000 ° of Ag by sputtering, 5000 mm of aluminum oxide on the transparent insulating layer 203 by vacuum evaporation, transparent conductive layer 205
Indium tin oxide and zinc oxide were deposited by sputtering at 2000 .ANG. And 1.3 .mu.m, respectively.

Then, a pin is formed on the transparent conductive layer 205.
A semiconductor layer 206 having three junctions was manufactured. Specifically, the first doped layer n-type a-si: H: P / the first i-layer a-SiGe: H / the second doped layer p-type μc-Si:
H: B / third doped layer n-type a-si: H: P / second i-layer a-SiGe: H / fourth doped layer p-type μc-S
i: H: B / fifth doped layer n-type a-Si: H: P / first i-layer a-Si: H / sixth doped layer p-type μc-S
i: H: B.

Then, 700 ° of indium tin oxide was formed thereon as the transparent electrode layer 207, and Cu was formed as the current collecting electrode 208.
A wire / Ag / C was formed to obtain a solar cell.

Comparative Example 2 A solar cell was obtained in the same manner as in Example 2 except that the transparent insulating layer 203 was not formed.

For Example 2 and Comparative Example 2, the initial conversion efficiency, the initial series resistance, and the series resistance after 100 hours of high temperature and high humidity were measured. Table 2 shows the results.

[0079]

[Table 2]

As a result of the test, the series resistance after 0 hour and 100 hours in Example 2 did not change, whereas that in Comparative Example 2 decreased. This is considered to be due to the migration of Ag due to reverse bias and moisture. On the other hand, as in Example 1, the structure is such that an electric field is not directly applied to Ag and migration of water is prevented by the transparent insulating layer, so that migration does not occur.

Example 3 A photovoltaic element shown in FIG. 3 was manufactured by the following procedure.

5 × 5 cm ² SU as support 301
S304: Ag as the light reflection layer 302 on the substrate, 5000 ° by vacuum deposition, 8000 °, magnesium fluoride by vacuum deposition on the transparent insulating layer 303, the second current collecting electrode 304
Au was deposited at 2000 .ANG., And indium tin oxide and zinc oxide were deposited at 2000 .ANG. And 1.0 .mu.m as the transparent conductive layer 305 by sputtering, respectively.

Then, a pin is formed on the transparent conductive layer 305.
A semiconductor layer 306 having three junctions was manufactured. Specifically, the first doped layer n-type a-Si: H: P / first i-layer a-SiGe: H / second doped layer p-type μc-Si:
H: B / third doped layer n-type a-si: H: P / second i-layer a-SiGe: H / fourth doped layer p-type μc-S
i: H: B / fifth doped layer n-type a-si: H: P / first i-layer a-Si: H / sixth doped layer p-type μc-S
i: H: B.

Then, a first current collecting electrode 308 composed of indium tin oxide as a transparent electrode layer 307 made of indium tin oxide at a thickness of 600.degree. And Au8000 as a comb was formed thereon, thereby completing a solar cell.

As compared with the second embodiment, the light conversion efficiency of the third embodiment was as good as about 1.05 times.

(Example 4) A solar cell was manufactured in the same manner as in Example 3 except that only zinc oxide was used instead of indium tin oxide and zinc oxide as the transparent conductive layer 305.

Even when zinc oxide having relatively high resistance was used as the transparent conductive layer 305, good results could be obtained by providing the second current collecting electrode 305.

(Example 5) The laser scribing process was performed on the photovoltaic element manufactured in Example 2 to obtain FIG.
The integrated solar cell shown in the following was prepared. The laser scribe uses a YAG laser, one of which is 0.25 cm ²
Were produced and connected in series to form one module.

[0089] was carried out compared with the 2.5 cm ² module, integrated module exhibited open circuit voltage 10 times, short-circuit current 0.96 times and good results against the 2.5 cm ² module.

(Embodiment 6) By performing laser scribing on the photovoltaic element fabricated in Embodiment 3,
The integrated solar cell shown in the following was prepared. The laser scribe uses a YAG laser, one of which is 0.30 cm ²
Were produced and connected in series to form one module.

[0091] was carried out compared to 3.0cm ² of the module, 14.3 times the open-circuit voltage with respect to an integrated module of 3.0cm ² module, the short-circuit current 0.97
The result was twice as good.

[0092]

The substrate for a photovoltaic element of the present invention is made of Ag, C
Although the reflectance of u or the like is high but migration is caused by the light reflecting layer of the photovoltaic element, the migration can be suppressed while maintaining a high reflectance. In addition, by having the substrate structure of the present invention, irregular reflection of light can be promoted and the photoelectric conversion efficiency can be improved.

Further, the solar cell fabricated on this substrate is excellent in use as an integrated photovoltaic element by performing laser scribing or the like.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a substrate for a photovoltaic element of the present invention.

FIG. 2 is a schematic sectional view showing an example of the photovoltaic device of the present invention.

FIG. 3 is a schematic sectional view showing another example of the photovoltaic element of the present invention.

FIG. 4 is a schematic sectional view showing an example of the integrated photovoltaic device of the present invention.

FIG. 5 is a schematic sectional view showing another example of the integrated photovoltaic device of the present invention.

FIG. 6 is a schematic sectional view showing a substrate for a photovoltaic element of the present invention.

[Explanation of symbols]

101, 201, 301, 401, 501, 601 Support 102, 202, 302, 402, 502, 602 Light reflective layer 103, 203, 303, 403, 503 Transparent insulating layer 304, 504 Second current collecting electrode 105, 205, 305, 405, 505, 605 Transparent conductive layer 206, 306, 406, 506 Semiconductor layer 207, 307, 407, 507 Transparent electrode layer 208, 408 Collector electrode 308, 508 First collector electrode

Claims (15)

[Claims] 1. A substrate for a photovoltaic device, comprising: a light reflecting layer and a transparent insulating layer sequentially laminated on a support. 2. The substrate for a photovoltaic device according to claim 1, further comprising a current collecting electrode on the transparent insulating layer. 3. The substrate for a photovoltaic device according to claim 1, wherein the light reflecting layer is made of gold, silver, copper, aluminum, or an alloy containing these metals as a main component. . 4. The transparent insulating layer is made of aluminum oxide, magnesium fluoride, silicon oxide, silicon nitride, titanium oxide,
The substrate for a photovoltaic device according to any one of claims 1 to 3, comprising at least one layer made of zinc sulfide, cesium fluoride, zirconium oxide, or a composite oxide thereof. 5. A photovoltaic device comprising: a transparent electroconductive layer, a semiconductor layer, a transparent electrode layer, and a collecting electrode sequentially laminated on the photovoltaic element substrate according to claim 1. element. 6. The photovoltaic device according to claim 5, wherein the light reflection layer and the semiconductor layer are insulated. 7. The semiconductor layer is a stack of at least one non-single-crystal n-type or p-type layer containing silicon atoms, a non-single-crystal i-type layer, and a non-single-crystal p-type or n-type layer. 7. The photovoltaic device according to claim 5, wherein the photovoltaic device has a pin structure. 8. The transparent conductive layer comprises at least one of indium oxide, tin oxide, indium tin oxide, zinc oxide, cadmium oxide, cadmium tin oxide, bismuth oxide, molybdenum oxide or a composite oxide thereof. The photovoltaic element according to claim 5. 9. A plurality of photovoltaic elements formed by sequentially laminating a transparent conductive layer, a semiconductor layer, a transparent electrode layer, and a collecting electrode on the photovoltaic element substrate according to claim 1. An integrated photovoltaic device, characterized in that: 10. The integrated photovoltaic device according to claim 9, wherein the light reflection layer and the semiconductor layer are insulated. 11. A semiconductor layer comprising at least one non-single-crystal n-type or p-type layer containing silicon atoms, a non-single-crystal i-type layer, and a non-single-crystal p-type layer or n-type layer containing at least one structure 10. A pin structure comprising:
Or an integrated photovoltaic device according to item 10. 12. The transparent conductive layer comprises at least one of indium oxide, tin oxide, indium tin oxide, zinc oxide, cadmium oxide, cadmium tin oxide, bismuth oxide, molybdenum oxide or a composite oxide thereof. The integrated photovoltaic device according to claim 9. 13. The integrated type according to claim 9, wherein a transparent conductive layer of one photovoltaic element and a transparent electrode layer of another photovoltaic element are connected in series. Photovoltaic element. 14. The integrated photovoltaic device according to claim 9, wherein the transparent conductive layers and the transparent electrode layers of the photovoltaic device are connected in parallel. 15. A step of laminating a transparent conductive layer, a semiconductor layer, a transparent electrode layer, and a collector electrode on the substrate for a photovoltaic element according to claim 1 or 2, and a plurality of photovoltaic elements using a laser. And a method of manufacturing the integrated photovoltaic device.