JPH07193264A - Solar cell - Google Patents

Abstract

PURPOSE:To restrain impurities diffusion from a substrate at the time of manufacturing or impurities diffusion between semiconductors, by forming a tetrahedral amorphous carbon layer, a photoelectric conversion layer, and a photo detection surface electrode in order on a substrate. CONSTITUTION:On a metal electrode substrate 11 composed of stainless, the following are laminated in order; an N-type tetrahedral amorphous carbon layer 12, a photoelectric conversion layer, i.e., an N-type amorphous semiconductor layer 14, an I-type amorphous semiconductor layer 15, a P-type amorphous semiconductor layer 16, and a transparent conductive film electrode 11, on which a collector electrode 18 is formed. Since the tetrahedral amorphous carbon film 12 does not form grain boundary, diffusion of impurities can be more effectively blocked. A photoelectric conversion layer of excellent quality can be formed by laminating amorphous semiconductor layers in the order of the N-layer, the I-layer, and the P-layer. Ohmic contact can be obtained by putting a P<+> type amorphous semiconductor between the P-type carbon thin film and the N-type photoelectric conversion layer.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to the structure of solar cells.

[0002]

2. Description of the Related Art There are solar cells in which a photoelectric conversion layer is formed by a pn junction and those in which a photoelectric conversion layer is formed by a pin junction. The pn junction is a crystalline system and the pin junction is an amorphous system. In an amorphous solar cell, a transparent conductive film electrode such as SnO ₂ or ITO is formed on a transparent insulating substrate such as glass, and an amorphous semiconductor p layer, i
A layer and an n layer are laminated in this order to form a photoelectric conversion layer,
A structure in which a metal thin film back electrode is laminated on it, or an amorphous semiconductor n layer, i layer, and p layer are laminated in this order on a metal substrate electrode to form a photoelectric conversion layer, on which a photoelectric conversion layer is formed. There is a structure in which transparent conductive film electrodes are laminated.

The photoelectric conversion layer is made of Si, GaAs, S.
It can be formed of various materials such as an inorganic material such as iC or an organic compound, and two or more kinds may be combined depending on the case in consideration of characteristics such as photoelectric conversion efficiency. For example, the p-layer on the light-receiving surface side of an amorphous solar cell having a pin junction or the n-layer in contact with the back electrode may be formed of carbon and the other layers may be formed of silicon (see, for example, Japanese Patent Laid-Open No. 1-212478, Kaihei 1-212479), in which the p-layer and the i-layer on the light-receiving surface side are formed of carbon, and the n-layer is formed of silicon carbide (for example, JP-A-2-34975). In these materials, the properties of the carbon film, that is, that the diffusion of impurities from the electrode film can be prevented and that the film has good light transmittance, are utilized.

[0004]

In the conventional solar cell,
It was not sufficient in terms of characteristics such as photoelectric conversion efficiency and light deterioration, and price. In particular, in a solar cell manufactured by depositing a photoelectric conversion layer on a substrate, diffusion of impurities into the photoelectric conversion layer during manufacturing has been a factor that hinders improvement in characteristics and cost reduction. For example, in order to produce a highly efficient amorphous silicon semiconductor photoelectric conversion layer with little photodegradation, the i layer is 300 to 4
It is preferable to control the amount of hydrogen in the a-Si: H thin film produced at a high temperature of 00 ° C. Further, as a result, the optical band gap Eg ^opt also becomes a narrow band gap from 1.75 eV to 1.65 eV due to the high temperature film formation, the short-circuit current increases, and the photoelectric conversion efficiency is improved. Incidentally, a-SiC and amorphous silicon alloys are other examples that can improve the characteristics by changing the band gap at such a high temperature. However, if a p-i-n layer is laminated in this order on the transparent conductive film electrode, i
When the layers are stacked, boron in the p-layer diffuses as an impurity into the i-layer, or the impurities diffuse from the transparent conductive electrode film to the p-layer to damage the light incident side of the photoelectric conversion layer to cause photoelectric conversion. There is a problem that the conversion characteristics are deteriorated. Further, when the n-i-p layers are laminated in this order on the metal film electrode, there is a problem that impurities are thermally diffused from the metal film electrode to the n layer, which also deteriorates the characteristics. Also, when a polycrystalline silicon thin film is formed on an inexpensive substrate such as a metal-grade silicon substrate to obtain a photoelectric conversion layer, impurities are diffused from the substrate into the polycrystalline silicon thin film, and a similar problem occurs. .

In view of the above, it is an object of the present invention to provide an inexpensive solar cell having high conversion efficiency by suppressing the impurity diffusion from the substrate or the impurity diffusion between the semiconductors during manufacturing.

[0006]

A solar cell according to the present invention comprises a substrate on which a carbon thin film having tetrahedral carbon bonds as a main component is formed, a photoelectric conversion layer formed on the carbon thin film, and the photoelectric conversion layer formed on the photoelectric conversion layer. It is characterized in that a light-receiving surface electrode is formed.

As the above-mentioned substrate, for example, a metal substrate such as stainless steel, an insulating substrate such as glass, a carbon substrate, a silicon substrate or the like can be used, and they are appropriately selected and used. For example, when the substrate has a role of a back electrode, it is preferable to use a metal substrate, a metal grade silicon substrate, or the like.

The carbon thin film mainly composed of the tetrahedral carbon bond is typically a thin diamond film,
There is a tetrahedral amorphous carbon (ta-C) film or the like, and a tetrahedral amorphous carbon film is particularly suitable for the present invention.

The carbon thin film is preferably p-type or n-type by adding impurities.

As the photoelectric conversion layer, a pin junction structure made of an amorphous semiconductor, a pn junction structure made of a polycrystalline semiconductor, or the like can be used, and the material is Si, GaAs, Si.
C or the like can be used and is appropriately selected. For example, as an amorphous semiconductor material, amorphous silicon (a-Si:
H), amorphous silicon germanium (a-SiGe:
H), amorphous silicon carbide (a-SiC: H),
A-Si such as amorphous silicon tin (a-SiSn: H)
There are system semiconductors, and it is easy to obtain relatively good characteristics.

When using a pin junction structure made of an amorphous semiconductor, an n layer, an i layer, and
It is preferable to stack the amorphous semiconductor layers in order of the p-layer to form a photoelectric conversion layer.

Further, in this case, the carbon thin film is of p-type, and a p ⁺ -type amorphous semiconductor layer is formed on the carbon thin film,
It is preferable to stack an amorphous semiconductor layer on the semiconductor layer in the order of n layer, i layer, and p layer to form a photoelectric conversion layer.

As the light-receiving surface electrode, a material such as metal or metal oxide can be used and is formed on the whole surface or a part of the photoelectric conversion layer. Then, the solar cell of the present invention is used such that light is incident from the side opposite to the substrate.

[0014]

In the solar cell of the present invention, since the carbon thin film having mainly tetrahedral carbon bond is provided between the substrate and the photoelectric conversion layer, the strong and short cc bond of the tetrahedral carbon causes the carbon thin film. Impurity diffusion from the substrate is prevented. Therefore, the structure is such that impurities can be prevented from entering from the substrate when the photoelectric conversion layer is formed. Since the tetrahedral carbon bond plays such a role, it is preferable that the tetrahedral carbon bond is the main component with respect to other bonds, and the ratio of the tetrahedral carbon bond is preferably high and the density thereof is also high.

Further, since the tetrahedral amorphous carbon film does not form grain boundaries unlike the thin diamond film, the diffusion of impurities can be prevented more effectively.

Further, the carbon thin film is doped with impurities to obtain p
If it is of the n-type or n-type, the conductivity is improved, and the generated current is easily extracted. Further, ohmic contact is easily obtained, and in particular, the carbon thin film and the photoelectric conversion layer are p-type.
Combining with p and n-n in succession is preferable because ohmic contact can be easily obtained.

Further, when the amorphous semiconductor layers are laminated in this order from the carbon thin film side, the n layer, the i layer and the p layer, the n layer, the i layer and the p layer can be laminated in this order at the time of manufacturing. Therefore, a photoelectric conversion layer of higher quality than that of p layer, i layer, and n layer stacked in this order is formed. This is because, for example, in an a-Si-based semiconductor, it is possible to avoid that boron, which is a doping material in the p-layer, is diffused and mixed into the i-layer, the influence of the impurity diffusion at the pi interface is eliminated, and the light incident side is eliminated. It is unavoidable that the photoelectric conversion efficiency is significantly affected if the p-layer side is damaged. However, in the case of the n-layer side, the p-layer and the i-layer have already been damaged in the process of incident light with p-i-n. This is because most of the incident light required for photoelectric conversion is absorbed, and the light required for photoelectric conversion that reaches the n-layer is essentially small, and the influence of impurities mixed in the ni interface is substantially reduced.

If a p ⁺ amorphous semiconductor layer is sandwiched between the p-type carbon thin film and the n layer of the photoelectric conversion layer, ohmic contact is obtained.

[0019]

EXAMPLES The present invention will be described in more detail below with reference to examples. Example 1 FIG. 1 is a schematic structural diagram of a solar cell of this example. The solar cell of the present embodiment has a metal electrode substrate 1 made of stainless steel.
A p-type thin film diamond layer 2, an amorphous semiconductor p ⁺ layer 3, an amorphous semiconductor n layer 4, an amorphous semiconductor i layer 5, an amorphous semiconductor p layer 6, and a transparent conductive film electrode 7 are formed on the Stack in this order,
It has a structure in which a collecting electrode 8 is formed on the transparent conductive film electrode 7.

The solar cell of this example is manufactured as follows. A p-type thin film diamond layer 2 doped with boron is formed on a stainless metal electrode substrate 1 by a microwave plasma CVD method. CH ₄ / H ₂ concentration 1 vol%, flow rate 250 sccm, doping gas 1
Flow rate of diborane gas diluted with hydrogen of 3%, gas pressure of 20 Torr, substrate temperature of 500 ° C., microwave power of 30
Deposition is performed to 150 nm with 0 W and a reaction time of 10 min. This thin-film diamond layer 2 has a texture structure, and can improve the efficiency of collecting light reflected from the back surface. As described above, the thin diamond film is preferable because the film itself can have a texture structure (not shown).

Next, the metal electrode substrate 1 is taken out from the microwave plasma CVD apparatus, the metal electrode substrate 1 is placed in the plasma CVD apparatus, and the substrate temperature is raised to 200.degree. The reaction gas is monosilane gas at a flow rate of 32 sccm, and the doping gas is diborane gas diluted with 5% hydrogen at a flow rate of 3
Flowing at 2 sccm to form an amorphous semiconductor p ⁺ layer 3 of a-Si: H. Even if the P ⁺ layer is formed on the surface of the n layer opposite to the contact surface with the i layer in this way, since it is far from the light incident surface, the influence of the photoelectric conversion efficiency reduction due to boron diffusion can be ignored. .

Subsequently, an amorphous semiconductor n layer 4 of a-Si: H is laminated to a thickness of 100 nm. The reaction gas is monosilane gas at a flow rate of 60 sccm, and hydrogen gas is at a flow rate of 3 sccc.
As the doping gas, a phosphine gas diluted with 0.3% hydrogen is flowed at a flow rate of 18 sccm. The amorphous semiconductor p ⁺ layer 3 and the amorphous semiconductor n layer 4 thus formed are in ohmic contact, and the thin film diamond layer 2 and the amorphous semiconductor p ⁺ layer 4 are formed.
Layer 3 is also in ohmic contact. Thus, it is preferable that the carbon thin film and the photoelectric conversion layer make ohmic contact.

Then, an amorphous semiconductor i layer 5 of a-Si: H is formed.
Are laminated to a thickness of 400 nm. At this time, the substrate temperature is 3
The temperature is raised to 50 ° C., and the reaction gas is monosilane gas at a flow rate of 60.
sccm, carrier gas is hydrogen gas at a flow rate of 20 sccm
Flush with. Even if the substrate is heated to such a high temperature, impurity diffusion from the metal electrode substrate to the amorphous semiconductor layer is blocked by the p-type thin film diamond layer.

Subsequently, an amorphous semiconductor p layer 6 of a-SiC: H is laminated to a thickness of 12 nm. In this case, the substrate temperature is lowered to 200 ° C., the reaction gas is a monosilane gas flow rate of 30 sccm, the methane gas flow rate is 89 sccm, the carrier gas is a hydrogen gas flow rate of 150 sccm, and the doping gas is a diborane gas diluted with 1% flow rate of 10 sccm.
Flush with.

After stacking the amorphous semiconductor photoelectric conversion layer in this way, 60 n of ITO as a transparent conductive film electrode is formed thereon.
The thickness of m is laminated by the DC magnetron sputtering method. Then, a collecting electrode 8 is formed on the electrode so as to partially cover the surface. The same applies to the following examples, but SnO ₂ , In ₂ O ₃ , ZnO, or the like can also be used as the transparent conductive film.

The characteristics of the thin film solar cell of this embodiment are AM
Isc: 20 at 1.5 (100 mW / cm ² ).
6 mA / cm ² , Voc: 0.87 V, F.I. F. : 0.
74, Pmax: 13.3 mW / cm ² .

Embodiment 2 FIG. 2 is a schematic structural diagram of a solar cell of the second embodiment. The solar cell according to the present embodiment includes an n-type tetrahedral amorphous carbon layer 12 on a metal electrode substrate 11 made of stainless steel,
An amorphous semiconductor n layer 14, an amorphous semiconductor i layer 15, an amorphous semiconductor p layer 16, and a transparent conductive film electrode 17 are laminated in this order, and a collector electrode 18 is formed on the transparent conductive film electrode 17. It has a structure.

The solar cell of this example is manufactured as follows. First, the n-type tetrahedral amorphous carbon layer 12 is formed on the metal electrode substrate 11. Non-doped tetrahedral amorphous carbon (ta-C) is sp
80% or more of ³ hybrid orbital bonds and the rest of sp ² hybrid orbital bonds and a structure of amorphous carbon, optical band gap: 1.8 to 2.2 eV, density of states near Fermi level: 10 ¹⁸ cm ^-3 eV ^-1 , wavelength quantum light of 450 to 800 nm, external quantum efficiency: 10%, conductivity: 10 ^-7 to 10 ^-8 Sc
m ^-1 , a slightly brown transparent film. This film is FCVA
It can be formed by a (filtered cathodic vacuum arc) method, and a high-purity carbon disk of the cathode is ionized by arc discharge, and this plasma beam is passed through a magnetic field filter to be deposited as a thin film. Since it is produced in this manner, the tetrahedral amorphous carbon does not contain hydrogen in its structure. In the present embodiment, this is doped with phosphorus ions to obtain n.
Use as a mold. This was done by using a phosphorus-containing carbon disk for the cathode, with n containing 0.1-1% phosphorus.
Type tetrahedral amorphous carbon (n-type ta)
-C) is formed. Conductivity: 10 ^-3 ~ due to phosphorus doping
10 ⁻⁴ Scm ⁻¹ , but the optical bandgap and sp
^{The three-} hybrid orbital coupling is the same as in the undoped state. The deposition rate is 150 nm / min, and 100 nm is deposited.

Next, an a-Si: H amorphous semiconductor n layer 14 is formed.
Are laminated to a thickness of 100 nm. The substrate is placed in a plasma CVD apparatus and the substrate temperature is raised to 200 ° C. The reaction gas is a monosilane gas at a flow rate of 60 sccm, the hydrogen gas is at a flow rate of 3 sccm, and the doping gas is a phosphine gas diluted with 0.3% hydrogen at a flow rate of 18 sccm. With such a structure, the n-type tetrahedral amorphous carbon layer 12 and the amorphous semiconductor n layer 14 are in ohmic contact.

Next, an amorphous semiconductor i layer 1 of a-Si: H
5 is laminated to a thickness of 500 nm. At this time, the substrate temperature is raised to 350 ° C., and the reaction gas is monosilane gas at a flow rate of 6
0 sccm, hydrogen gas is flown at a flow rate of 20 sccm.

Subsequently, an amorphous semiconductor p layer 16 of a-SiC: H is laminated to a thickness of 12 nm. In this case, the substrate temperature is lowered to 200 ° C., the reaction gas is monosilane gas at a flow rate of 30 sccm, the methane gas is at a flow rate of 89 sccm, the carrier gas is hydrogen gas at a flow rate of 150 sccm, and the doping gas is 1% dilute diborane gas at a flow rate of 10 sccc.
Flow at m.

After laminating the amorphous semiconductor layer in this manner, ITO having a thickness of 60 nm is laminated thereon as the transparent conductive film electrode 17 by the DC magnetron sputtering method. Then, a collector electrode 18 is formed on this so as to partially cover the surface.

The characteristics of the single-layer thin-film solar cell manufactured according to this example are as follows: AMc (100 mW / cm ² ) Isc: 20.3 mA / cm ² , Voc: 0.88
V, F. F. : 0.74, Pmax: 13.2 mW / c
It was m ² . In this example, the characteristics equivalent to those of the solar cell of Example 1 were obtained even though no texture structure was provided. This is because the tetrahedral amorphous carbon layer has a high efficiency of blocking impurities.

Embodiment 3 FIG. 3 is a schematic structural diagram of a solar cell of the third embodiment. The solar cell of this example comprises an n-type tetrahedral amorphous carbon layer 22 on a metal electrode substrate 21 made of stainless steel,
Amorphous semiconductor n layer 24, amorphous semiconductor i layer 25, amorphous semiconductor p layer 26, amorphous semiconductor n layer 34, amorphous semiconductor i layer 35, amorphous semiconductor p layer 36, transparent conductivity Membrane electrode 2
7 is laminated in this order, and a collecting electrode 28 is formed on the transparent conductive film electrode 27. The solar cell of this example is a tandem structure solar cell in which two photoelectric conversion layers of Example 2 are laminated.

The solar cell of this example is manufactured as follows. First, the n-type tetrahedral amorphous carbon layer 22 is formed on the metal electrode substrate 21. The manufacturing method is F
A CVA (filtered cathodic vacuum arc) method is used to ionize a cathode-containing carbon disk containing phosphorus by arc discharge, deposit a plasma beam as a thin film through a magnetic field filter, and then deposit 0.1 to 1% phosphorus-containing n-type tetrahedral Amorphous carbon (n-type ta-C) is formed. The deposition rate is 150 nm / min, and 100 nm is deposited. Conductivity: 10 ^-3 to 10 ^-4 S due to phosphorus doping
It becomes cm ^-1 .

Next, the first-stage amorphous semiconductor n layer 24 of a-Si: H is laminated to a thickness of 100 nm. Plasma C
The substrate is placed in the VD apparatus and the substrate temperature is raised to 200 ° C. The reaction gas is a monosilane gas at a flow rate of 60 sccm, the hydrogen gas is at a flow rate of 20 sccm, and the doping gas is a 2% phosphine gas at a flow rate of 0.35 sccm. The reaction pressure is 0.12 torr. The n-type tetrahedral amorphous carbon layer 22 and the amorphous semiconductor n layer 24 are in ohmic contact. Then, an amorphous semiconductor i layer 25 of a-Si: H is laminated to a thickness of 200 nm. At this time, the substrate temperature is increased to 350 ° C., the reaction gas is monosilane gas at a flow rate of 60 sccm, and the hydrogen gas is at a flow rate of 20 sccc.
The reaction is carried out at a reaction pressure of 12 torr. Subsequently, an amorphous semiconductor p-layer 26 of a-SiC: H is stacked to a thickness of 10 nm. In this case, the substrate temperature is lowered to 200 ° C., and the reaction gas is monosilane gas at a flow rate of 30 ml / mi.
n, a flow rate of methane gas is 35.6 sccm, a carrier gas is hydrogen gas at a flow rate of 160 sccm, and a doping gas is 0.6% diborane gas at a flow rate of 0.06 sccm, and the reaction is performed at a reaction pressure of 0.32 torr.

Subsequently, a second-stage a-Si: H amorphous semiconductor n ⁺ layer 34 is deposited to a thickness of 5 nm. The substrate temperature is 200 ° C., and the n ⁺ layer makes ohmic contact with the underlying p layer, so the doping amount is doubled. The reaction gas is monosilane gas at a flow rate of 60 sccm and hydrogen gas at a flow rate of 20 sc
m, doping gas is 2% phosphine gas for 2s
Flow at ccm and react at a reaction pressure of 0.12 torr. Subsequently, the second-stage amorphous semiconductor i layer 35 of a-Si: H is deposited to a thickness of 150 nm. Substrate temperature is 200
The reaction gas is monosilane gas at a flow rate of 60 sccm,
Hydrogen gas was flown at a flow rate of 20 sccm, and the reaction pressure was 0.12.
React at torr. Then, the second stage a-SiC:
An amorphous semiconductor p layer 36 of H is deposited to a thickness of 10 nm. The substrate temperature is 200 ° C., the reaction gas is monosilane gas at a flow rate of 30 sccm, and methane gas is at a flow rate of 35.6 scc.
m, hydrogen gas at a flow rate of 160 sccm, and 0.6% diborane gas as a doping gas at a flow rate of 0.06 sccm, and the reaction is performed at a reaction pressure of 0.32 torr.

After the amorphous semiconductor photoelectric conversion layer is formed in this way, ITO is used as the transparent conductive film electrode 27 on the amorphous semiconductor photoelectric conversion layer.
The layers are stacked with a thickness of 0 nm by the DC magnetron sputtering method. Then, a collector electrode 28 is formed on this so as to partially cover the surface. In this way, the two-stage dandem
Metal electrode / n-type ta-C / n (a-Si: H) / i (a-Si: H) / p (aS
A thin film solar cell of iC: H) / n (a-Si: H) / i (a-Si: H) / p (a-SiC: H) / ITO structure is produced.

The characteristics of the solar cell of this embodiment are AM1.5.
Isc: 10.1 mA at (100 mW / cm ² ).
/ Cm ² , Voc: 1.78V, F.I. F. : 0.75,
The Pmax was 13.4 mW / cm ² .

In the above embodiments, since the film is formed by the CVD method, it is suitable for a large area solar cell. As described above, when an amorphous semiconductor is used, vapor phase growth by plasma CVD method or photo CVD method by glow discharge decomposition of a raw material is possible, and it is suitable for forming a thin film on a large area. Further, in the case of an amorphous semiconductor, since the light absorption efficiency is generally poor, it is preferable to make the carbon thin film transparent so that the light is reflected on the substrate surface. In this case, the structure is simplified if the substrate itself has a reflection characteristic as in the present embodiment.
It is not necessary to make it transparent when light is sufficiently absorbed as in the case of using a silicon polycrystalline semiconductor. Further, the carbon thin film itself may have a reflection characteristic.

[0041]

According to the solar cell of the present invention, since the carbon thin film mainly containing tetrahedral carbon bonds is provided between the substrate and the photoelectric conversion layer, diffusion of impurities from the substrate is prevented, and This makes it possible to use an inexpensive substrate containing impurities. Further, when an amorphous semiconductor is used, it is possible to use a high-efficiency or low-degradation a-Si: H film or the like that can raise the temperature of the substrate at the time of laminating the i-layer and can be formed by the high-temperature laminating as compared with the conventional case. It will be possible.

If a tetrahedral amorphous carbon film is used, the diffusion of impurities can be prevented more effectively.

When the carbon thin film is added with impurities to be p-type or n-type, the conductivity is improved and the generated current can be efficiently taken out.

Further, when the amorphous semiconductor layer is laminated in the order of the n layer, the i layer, and the p layer from the carbon thin film side, it is possible to prevent adverse effects due to impurity diffusion between the semiconductor layers.

Furthermore, if a p ⁺ semiconductor layer is sandwiched between the p-type carbon thin film and the n layer of the photoelectric conversion layer, ohmic contact can be obtained even if a p-type carbon thin film is used, and the generated current is generated. Can be taken out efficiently.

From the above, according to the present invention, it is possible to manufacture a solar cell with high efficiency, low deterioration or low cost.

[Brief description of drawings]

FIG. 1 is a schematic structural diagram of a solar cell using a p-type thin film diamond layer of a first embodiment.

FIG. 2 is a schematic structural diagram of a solar cell using an n-type tetrahedral amorphous carbon layer of a second embodiment.

FIG. 3 is a schematic structural diagram of a tandem solar cell using an n-type tetrahedral amorphous carbon layer of a third embodiment.

[Explanation of symbols]

1,11,21 metal electrode substrate 2 p-type thin film diamond layer 12,22 n-type tetrahedral amorphous carbon layer 3 amorphous semiconductor p ⁺ layer (a-Si: H) 4,14,24 amorphous semiconductor n Layer (a-Si: H) 34 Amorphous semiconductor n ⁺ layer (a-Si: H) 5,15,25,35 Amorphous semiconductor i layer (a-Si: H) 6,16,26,36 Amorphous semiconductor p layer (a-SiC: H) 7,17,27 Transparent conductive film electrode 8,18,28 Collection electrode

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Koji Tomita 22-22 Nagaike-cho, Abeno-ku, Osaka-shi, Osaka

Claims (5)

[Claims] 1. A carbon thin film mainly containing tetrahedral carbon bonds is formed on a substrate, a photoelectric conversion layer is formed on the carbon thin film, and a light-receiving surface electrode is formed on the photoelectric conversion layer. And solar cells. 2. The solar cell according to claim 1, wherein the carbon thin film is tetrahedral amorphous carbon. 3. The solar cell according to claim 1, wherein the carbon thin film is p-type or n-type by adding impurities. 4. The solar cell according to claim 3, wherein an amorphous semiconductor layer is laminated in this order from the carbon thin film side to an n layer, an i layer, and ap layer to form a photoelectric conversion layer. 5. The carbon thin film is a p-type, a p ⁺ -type amorphous semiconductor layer is formed on the carbon thin film, and an n-layer, an i-layer, and a p-layer are amorphous in this order on the semiconductor layer. 5. The photoelectric conversion layer is formed by stacking semiconductor layers.
Solar cells.