JP2013179217A - Solar cell and manufacturing method for the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar cell which can reduce reflection of light from an interface between a photoelectric conversion layer and a transparent conductive layer by forming a moth eye structure of conductive material on the transparent conductive layer having a texture structure.SOLUTION: There are provided a solar cell comprising: a transparent substrate; a first transparent conductive layer having a texture structure; a second transparent conductive layer having a moth eye structure; and a photoelectric conversion layer, in this order from the light incident side, and a method for manufacturing a solar cell comprising: a transparent substrate; a first transparent conductive layer having a texture structure; a second transparent conductive layer having a moth eye structure; and a photoelectric conversion layer, in this order from the light incident side. The method comprises the step of depositing the second transparent conductive layer in a precursor solution containing metal source and hexamethylene where the temperature is maintained at 50 to 100°C.

Description

  The present invention provides means capable of improving the conversion efficiency of a solar cell, and particularly relates to an improvement of a transparent conductive layer in a solar cell.

Currently, many thin film solar cells are fabricated on a transparent conductive layer. The transparent conductive layer ITO, SnO 2, _ZnO or _the like is present, the surface structure to those having a textured structure from flat or a variety according to the use purpose. In order to improve the performance of these solar cells, it is necessary to reduce losses such as light loss due to light reflection, loss due to charge recombination, loss due to incomplete use of energy, and electrical loss due to resistance.

  The photoelectric conversion layer of a solar cell has a large refractive index, and there is a concern that light loss due to light reflection at the interface between the transparent conductive layer and the antireflection technology at the interface between the transparent conductive layer and the photoelectric conversion layer is required. Yes.

  On the other hand, as a technique for preventing reflection on a transparent substrate such as glass, for example, JP-T-2001-517319 (Patent Document 1), JP-A-2004-205990 (Patent Document 2), JP-A-2004-287238 ( Patent Document 3), Japanese Patent Application Laid-Open No. 2001-272505 (Patent Document 4), Japanese Patent Application Laid-Open No. 2002-286906 (Patent Document 5), and the like have a period of unevenness of about 100 nm controlled to be equal to or less than the wavelength of visible light. A technique for preventing reflection by forming a fine uneven pattern on the surface is disclosed. Such a method uses the principle of a so-called moth eye structure, and continuously changes the refractive index for light incident on the substrate, thereby eliminating the discontinuous interface of the refractive index. This prevents light reflection. Such a moth-eye structure is generally manufactured by transferring the irregularities to an arbitrary flat resin layer using a mold (stamper or mold) having a shape obtained by inverting the fine irregularities. Is.

JP-T-2001-517319 JP 2004-205990 A JP 2004-287238 A JP 2001-272505 A JP 2002-286906 A

  However, in order to apply to the interface between the photoelectric conversion layer and the transparent conductive layer of a solar cell, the material having a moth-eye structure must have high transparency and conductivity in order not to deteriorate the characteristics of the transparent conductive layer. Insulators such as resins have a problem that electrons cannot be taken out when operated as a solar cell. In addition, the moth-eye structure can be formed mainly on a flat surface, and it is difficult to form the moth-eye structure without depending on the properties and structure of the transparent conductive layer.

  In addition, in order to scatter light and confine light in the photoelectric conversion layer (light confinement effect), a texture structure having pyramidal irregularities is generally formed on the transparent conductive layer for solar cells. . In order to maintain this light confinement effect, a moth-eye structure has to be formed on the texture structure, and the conventional technique cannot be applied as it is.

  As described above, it is desired that the transparent conductive layer has higher transmittance and lower resistance. Although the moth-eye structure is effective for increasing the transmittance of the transparent conductive layer, the transparent conductive layer has a moth-eye structure. In order to give, the technique in which a material has transparency and electroconductivity, and it can produce without depending on the structure of a transparent conductive layer is needed.

  The present invention has been made in order to solve the above-described problems. The object of the present invention is to form a moth-eye structure with a transparent conductive material on a transparent conductive layer having a textured structure. It is an object of the present invention to provide a solar cell that can reduce the light reflection at the interface between the conversion layer and the transparent conductive layer.

  The solar cell of the present invention includes a transparent substrate, a first transparent conductive layer, a second transparent conductive layer, and a photoelectric conversion layer in this order from the light incident side, and the first transparent conductive layer has a texture structure. The second transparent conductive layer has a moth-eye structure.

  In the solar cell of the present invention, it is preferable that the concavo-convex convex portion of the moth-eye structure in the second transparent conductive layer has a height in the range of 10 to 300 nm and a diameter in the range of 10 to 100 nm.

  In the solar cell of the present invention, it is preferable that the second transparent conductive layer contains zinc oxide, and in this case, it is more preferable that the first transparent conductive layer contains tin oxide.

  In the solar cell of the present invention, the third transparent conductive layer is formed of the same material as the second transparent conductive layer between the first transparent conductive layer and the second transparent conductive layer, and has no moth-eye structure. The transparent conductive layer is preferably formed.

  The present invention also comprises a transparent base material, a first transparent conductive layer, a second transparent conductive layer, and a photoelectric conversion layer in this order from the light incident side, the first transparent conductive layer having a texture structure, The second transparent conductive layer is a method for producing a solar cell having a moth-eye structure, and the second transparent conductive layer is maintained by holding a precursor aqueous solution containing a metal source and hexamethylenetetramine at 50 to 100 ° C. A method for producing a solar cell including a step of depositing a layer is also provided.

  In the method for manufacturing a solar cell of the present invention, the first transparent conductive layer is formed of tin oxide, the second transparent conductive layer is formed of zinc oxide, and the second transparent conductive layer is formed. It is preferable to include a step of performing heat treatment at ˜300 ° C.

  According to the present invention, the refractive index between the first transparent conductive layer and the photoelectric conversion layer can be continuously changed, and reflection of light is prevented by eliminating the discontinuous interface of the refractive index. Can do. Thereby, the number of photons which penetrate | invade into a photoelectric converting layer can be increased, and a highly efficient solar cell is provided.

It is sectional drawing which shows typically the solar cell 1 of a preferable example of this invention. 4 is a SEM photograph showing the texture structure of the surface of the first transparent conductive layer 3 in the solar cell 1 used in Experimental Example 1. 4 is an SEM photograph showing a moth-eye structure on the surface of a second transparent conductive layer 4 in the solar cell 1 produced in Experimental Example 1. It is the graph which showed the transmittance | permeability improvement by having formed the 2nd transparent conductive layer. It is the graph which showed the reflectance fall of the solar cell by having formed the 2nd transparent conductive layer.

  FIG. 1 is a cross-sectional view schematically showing a preferred example solar cell 1 of the present invention. As shown in FIG. 1, the solar cell 1 of the present invention includes a transparent substrate 2, a first transparent conductive layer 3, a second transparent conductive layer 4, and a photoelectric conversion layer 5 in this order from the light incident side, The first transparent conductive layer 3 has a texture structure, and the second transparent conductive layer 4 has a moth-eye structure. With such a structure, between the first transparent conductive layer 3 and the photoelectric conversion layer 5 (second transparent conductive layer, the second transparent conductive layer 4 and the third transparent conductive layer in the example shown in FIG. 1). The refractive index of the conductive layer 6) can be continuously changed, and light reflection can be prevented by eliminating the portion where the refractive index is discontinuous. Thereby, the number of photons that enter the photoelectric conversion layer can be increased.

  As the transparent substrate 2 in the solar cell 1 of the present invention, a heat-transmitting translucent resin such as polyimide and polyvinyl, glass, or a laminate of these can be used as appropriate. It is not particularly limited as long as it is high and can structurally support the entire solar cell.

The first transparent conductive layer 3 in the solar cell 1 of the present invention may be formed of a conventionally known appropriate transparent conductive material. Examples of such a material include tin oxide (SnO ₂ ) and zinc oxide ( ZnO), indium oxide and the like can be mentioned, but are not particularly limited. Especially, it is preferable that the 1st transparent conductive layer 3 is formed with the tin oxide from a viewpoint of the high electrical conductivity by the heat processing of 100-300 degreeC mentioned later. In addition to the transparent conductive material described above, the first transparent conductive layer 3 includes, for example, tin and fluorine for indium oxide, fluorine and antimony for tin oxide, and the like, as long as the effects of the present invention are not impaired. Zinc oxide may be added with a small amount of impurities such as indium, gallium, aluminum, and boron.

  The average thickness of the first transparent conductive layer 3 in the present invention is not particularly limited, but from the viewpoint of securing conductivity while suppressing absorption of infrared light as much as possible, it is in the range of 100 to 3000 nm. Is preferable, and it is more preferable to be in the range of 500 to 1500 nm.

  The first transparent conductive layer 3 in the present invention has a texture structure on the surface in order to have light scattering properties. The first transparent conductive layer 3 is formed by sputtering, atmospheric pressure CVD (Chemical Vapor Deposition), low pressure CVD, MOCVD (Metal Organic Chemical Vapor Deposition), electron beam evaporation, sol-gel method, electrodeposition, spraying. It can be formed by a conventionally known appropriate method such as a method. In addition, the texture structure may be formed when the first transparent conductive layer 3 is formed. However, after the first transparent conductive layer 3 is formed, a conventionally known appropriate structure such as dry etching or wet etching may be used. It can also be formed by a method.

  The second transparent conductive layer 4 in the present invention may also be formed of a conventionally known appropriate transparent conductive material as described above for the first transparent conductive layer 3. Especially, when amorphous silicon or the like is formed by the CVD method when the photoelectric conversion layer 5 is formed, it is exposed to H plasma, and thus is formed of zinc oxide having excellent H plasma resistance. It is preferable. As in the first transparent conductive layer 3 described above, the second transparent conductive layer 4 has a range that does not impair the effects of the present invention. For example, indium oxide has tin, fluorine, etc. A trace amount of impurities such as indium, gallium, aluminum, and boron may be added to zinc oxide such as fluorine and antimony.

  In order to take out electrons from the photoelectric conversion layer 5, the material forming the second transparent conductive layer 4 having a moth-eye structure must exhibit conductivity. In the conventional technology for forming a moth-eye structure, the material is generally an insulator. However, in the present invention, a material having transparent conductivity (for example, zinc oxide, tin oxide, etc. described above) is used. A moth-eye structure is formed. For example, zinc oxide can precipitate a crystal having a cylindrical one-dimensional nanostructure on the first transparent conductive layer 3 or the third transparent conductive layer 6 (described later) by chemical solution deposition, A desired moth-eye structure can be obtained by controlling the deposition conditions. Thereby, reflection can be prevented without impairing conductivity.

  The second transparent conductive layer 4 in the present invention has a moth-eye structure. In the moth-eye structure of the second transparent conductive layer 4, the height of the concavo-convex convex portion is preferably in the range of 10 to 300 nm, and more preferably in the range of 50 to 200 nm. This is because when the height of the convex portion of the moth-eye structure is less than 10 nm, the anti-reflection effect due to the moth-eye structure tends to be difficult to obtain, and when it exceeds 300 nm, light loss due to backscattering occurs. This is because it tends to increase.

  In addition, the moth-eye structure is the diameter of the concavo-convex convex portion (where the diameter refers to the maximum length of the length in any direction of the cross section when the convex sectional shape is not round) In the case of a cone, the diameter is the largest part.) Is preferably in the range of 10 to 100 nm, and more preferably in the range of 20 to 80 nm. When the diameter of the convex part of the moth-eye structure is less than 10 nm, it tends to be difficult to form the photoelectric conversion layer 5 in the gap of the moth-eye structure, and when it exceeds 100 nm, This is because light loss due to scattering tends to increase.

  In addition, the height and diameter of the convex part of the moth-eye structure of the second transparent conductive layer 4 described above were observed by using, for example, a field emission scanning electron microscope (XL30FEG) (manufactured by PHILIPS). The value calculated using the magnification at the time of observation from the cross-section and surface image of the transparent conductive layer.

  A method for forming the second transparent conductive layer 4 having such a moth-eye structure is not particularly limited, but a chemical solution deposition method is suitable. This is a structure in which a first transparent conductive layer 3 is formed on a transparent substrate 2 in a precursor solution containing a crystal raw material to be deposited later, or a first transparent conductive layer on a transparent substrate 2 Crystals are deposited on the first transparent conductive layer 3 or the third transparent conductive layer 6 by immersing the structure in which the third and third transparent conductive layers 6 (described later) are immersed and changing the temperature. It is a method to make it. By utilizing this chemical solution deposition method, crystals having various structures can be deposited by controlling the material, concentration, temperature, etc. of the precursor solution. A cylindrical or pyramidal structure that becomes a moth-eye structure can also be formed by this method. Furthermore, by this chemical solution deposition method, crystals can be deposited without depending on the shape of the first transparent conductive layer 3 or the third transparent conductive layer 6, and the first transparent conductive layer having a texture structure can be obtained. Even if it is above 3, it is possible to form a moth-eye structure. Thereby, both the light scattering by a texture and the reflection prevention by a moth eye can be made compatible, and the characteristic of a solar cell can be improved.

  Formation of the 2nd transparent conductive layer 4 provided with the moth eye structure using a chemical solution deposition method can be performed in the following procedures, for example. First, a precursor aqueous solution prepared by dissolving a metal source (acetate, hydrochloride, nitrate, sulfate, etc.) and hexamethylenetetramine (hereinafter “hexamine”) in water is prepared. Next, a structure in which the first transparent conductive layer 3 is formed on the transparent substrate 2, or a structure in which the first transparent conductive layer 3 and the third transparent conductive layer 6 are formed on the transparent substrate 2. Is immersed in the aqueous precursor solution described above, and the temperature of the solution is maintained at 50 to 100 ° C. As a result, the second transparent conductive layer 4 having a moth-eye structure is deposited on the first transparent conductive layer 3 or the third transparent conductive layer 6.

  As described above, the present invention includes the transparent substrate 2, the first transparent conductive layer 3, the second transparent conductive layer 4, and the photoelectric conversion layer 5 in this order from the light incident side, and the first transparent conductive layer 3. Has a texture structure, and the second transparent conductive layer 4 is a method of manufacturing a solar cell 1 having a moth-eye structure, and holds a precursor aqueous solution containing a metal source and hexamethylenetetramine at 50 to 100 ° C. Thus, a method for manufacturing the solar cell 1 including the step of depositing the second transparent conductive layer 4 is also provided. In addition, when the holding temperature of the precursor aqueous solution after immersing the structure is less than 50 ° C., there is a problem that the second transparent conductive layer 4 does not precipitate, and when it exceeds 100 ° C., There is a problem that the reaction is too fast and difficult to control, and the generated bubbles adhere to the first transparent conductive layer 3 and inhibit the uniform formation of the second transparent conductive layer 4. For these reasons, the holding temperature of the precursor aqueous solution after immersing the structure is preferably in the range of 50 to 100 ° C, more preferably in the range of 60 to 85 ° C. The formation of the second transparent conductive layer 4 can be performed by using a conventionally known appropriate apparatus / equipment. For example, a commercially available product such as a mantle heater (manufactured by Taishin Denki Co., Ltd.) is preferably used. Can be used.

  In such a method for manufacturing a solar cell of the present invention, when the first transparent conductive layer 3 is formed of tin oxide and the second transparent conductive layer 4 is formed of zinc oxide as described above, After forming the transparent conductive layer 4, it is preferable to perform heat treatment at 100 to 300 ° C. By performing such a heat treatment, the first transparent conductive layer and the second transparent conductive layer with improved conductivity can be manufactured, thereby suppressing not only light loss but also electrical loss. In addition, it is possible to manufacture a solar cell with further improved characteristics. When the heat treatment temperature is less than 100 ° C., the conductivity tends not to be improved, and when it exceeds 300 ° C., the conductivity tends to decrease. For these reasons, the heat treatment temperature after forming the second transparent conductive layer 4 is preferably in the range of 100 to 300 ° C, and more preferably in the range of 200 to 280 ° C. Such heat treatment can also be performed by using a conventionally known appropriate apparatus / equipment. For example, a commercially available product such as a constant temperature dryer (DR-22) (manufactured by Yamato Scientific Co., Ltd.) can be suitably used. .

  In the solar cell 1 of the present invention, the photoelectric conversion layer 5 is formed on the second transparent conductive layer 4 having the moth-eye structure described above. As a material of the photoelectric conversion layer 5, for example, a silicon-based material (amorphous, microcrystalline, polycrystalline), a CIGS-based material, a II-VI group-based material, a dye-sensitized metal oxide material, or the like can be used.

In the present invention, the method for forming the photoelectric conversion layer 5 is not particularly limited, and can be formed by appropriately combining conventionally known methods as necessary. For example, in the case of amorphous silicon, a case where the photoelectric conversion layer 5 is formed under the following conditions using a commercial product such as a plasma CVD apparatus (ACV-T440L type) (manufactured by Shinko Seiki Co., Ltd.) is exemplified. The
(P layer (10 nm))
Source gas and source gas flow rate: SiH ₄ : 6 sccm, CH ₄ : 10 sccm, H ₂ : 22 sccm, H ₂ (containing B ₂ H ₆ 0.1%): 18 sccm
・ Pressure: 30Pa
-Substrate temperature: 180 ° C
・ Distance between electrodes: 40mm
・ Power: 70W
(I layer (300 nm))
Source gas and source gas flow rate: SiH ₄ : 20 sccm, H ₂ : 50 sccm
・ Pressure: 30Pa
-Substrate temperature: 200 ° C
・ Distance between electrodes: 45mm
・ Power: 35W
(N layer (20 nm))
Source gas and source gas flow rate: SiH ₄ : 20 sccm, H ₂ : 25 sccm, H ₂ (including 0.2% PH ₃ ): 25 sccm
・ Pressure: 30Pa
-Substrate temperature: 200 ° C
・ Distance between electrodes: 45mm
・ Power: 35W
Moreover, the solar cell 1 of this invention is the same material as the 2nd transparent conductive layer 4 between the 1st transparent conductive layer 3 and the 2nd transparent conductive layer 4 like the example shown in FIG. A third transparent conductive layer 6 that is formed and does not have a moth-eye structure may be formed. By further including the third transparent conductive layer 6 as described above, the moth-eye structure of the second transparent conductive layer 4 becomes a denser and more homogeneous structure, and the antireflection effect can be increased.

  The average thickness of the third transparent conductive layer 6 in the present invention is not particularly limited, but the absorption of infrared light is suppressed as much as possible, and the second transparent conductive layer 4 to be formed later has a dense and uniform structure. Therefore, it is preferably in the range of 10 to 2000 nm, and more preferably in the range of 20 to 100 nm.

The method for forming the third transparent conductive layer 6 is not particularly limited, and a conventionally known method is appropriately combined as necessary to form a sputtering method, a vacuum deposition method, an ion plating method, a pulse laser deposition method. , A sol-gel method, a CVD method, or the like. For example, in the case of sputtering, the third transparent conductive layer 6 is formed on the first transparent conductive layer 3 under the following conditions using a commercially available product such as a sputtering apparatus (manufactured by Hirano Kotone Co., Ltd.). Is exemplified.
(Sputtering conditions)
・ Target: ZnO
・ Sputtering gas: Ar
Gas pressure: 4.0 mTorr
・ Input power: 1.5 kW
Hereinafter, although an example of an experiment is given and the present invention is explained in detail, the present invention is not limited to these.

<Experimental example 1>
First, a substrate (Asahi-U) having a texture structure and a transparent conductive layer (first transparent conductive layer 3) formed of SnO ₂ containing fluorine as an impurity on a glass substrate (transparent substrate 2). : Asahi Glass Co., Ltd.) FIG. 2 is an SEM photograph (magnified 80000 times) of the surface having the texture structure of the formed first transparent conductive layer 3. Next, a sputtering apparatus (manufactured by Hirano Kotone Co., Ltd.) was used to form a film for 3 minutes under the above-described conditions. On the first transparent conductive layer 3, a transparent conductive layer (third transparent film) made of ZnO and having a thickness of 50 nm was formed. A conductive layer 6) was formed.

  A precursor aqueous solution containing 0.025 mol / L zinc nitrate and 0.025 mol / L hexamine is prepared, and the first transparent conductive layer is formed on the transparent substrate 2 formed as described above in this precursor aqueous solution. The structure in which the third and third transparent conductive layers 6 were formed was immersed. By holding the temperature of the precursor aqueous solution at 80 ° C. for 30 minutes, columnar zinc oxide crystals having a convex portion height in the range of 30 to 150 nm and a diameter in the range of 15 to 80 nm are precipitated. did. In this way, the second transparent conductive layer 4 having a moth-eye structure was formed on the third transparent conductive layer 6. FIG. 3 is an SEM photograph (magnified 80000 times) of the surface of the formed second transparent conductive layer 4 having a moth-eye structure.

Here, FIG. 4 is a graph showing the improvement of the transmittance of the transparent conductive layer by the second transparent conductive layer produced according to the present invention, where the vertical axis represents the transmittance (%) and the horizontal axis represents the wavelength (nm). is there. FIG. 4 shows a measurement result of transmittance at a wavelength in the range of 300 to 1100 nm using a spectrophotometer (UV-3150) (manufactured by Shimadzu Corporation). In the graph, the solid line is the second line. As a result of the sample (glass / SnO ₂ / moth eye ZnO) after forming the transparent conductive layer 4, the result of the sample (glass / SnO ₂ ) before forming the second transparent conductive layer 4 for reference as a broken line Respectively. Note that the reference sample does not have the third transparent conductive layer 6 described above. FIG. 4 shows that the transmittance in the visible light region (400 to 1000 nm) is increased by 8.5% at the maximum by forming the second transparent conductive layer 4 having the moth-eye structure.

  Moreover, when the haze rate was measured about the above-mentioned sample using the haze meter (NDH5000) (made by Nippon Denshoku Industries Co., Ltd.), in the structure before forming the 2nd transparent conductive layer 4, 16.6%, In the structure after forming the second transparent conductive layer 4, it was 16.7%. That is, even when the second transparent conductive layer 4 was formed, the transmittance could be improved with almost no change in light scattering properties.

In addition, the sample (glass / SnO ₂ ) before forming the second transparent conductive layer 4 (the above-described third transparent conductive layer 6 is not formed in the sample) and the second transparent conductive layer 4 are formed. In addition to the formed sample (glass / SnO ₂ / moth eye ZnO), a sample (glass / SnO ₂ / moth eye ZnO (heat treatment: 260 ° C.) subjected to heat treatment at 260 ° C. for 90 minutes after the formation of the second transparent conductive layer 4 was further formed. , 90 minutes), sheet resistance (Ω / □) was measured using a sheet resistance measuring device (RT-8A / RG-8) (manufactured by Napson Co., Ltd.) Table 1 shows the results. As can be seen, even when the second transparent conductive layer 4 is formed, the sheet resistance hardly increases, and by performing the heat treatment as described above, the resistance can be lowered and the conductivity can be improved. This It can be seen.

  A photoelectric conversion layer 5 is formed of amorphous silicon on the second transparent conductive layer 4, and a back electrode (not shown) is formed using zinc oxide (ZnO) and silver (Ag). A battery sample was obtained. On the other hand, a sample in which the photoelectric conversion layer 5 and the back electrode were formed on the first transparent conductive layer 3 in the same manner as described above without forming the second transparent conductive layer 4 was obtained.

For each sample, light is incident from the transparent substrate 2 side, and the result of measuring the total reflectance using a thin film layer evaluation apparatus (manufactured by Maki Seisakusho) is shown in FIG. In FIG. 5, the vertical axis represents total reflectance (%), and the horizontal axis represents wavelength (nm). In the graph, the solid line represents a sample (glass / SnO ₂ / moth eye) after the second transparent conductive layer 4 is formed. As a result of ZnO / a-Si / ZnO / Ag), a broken line indicates a result of a sample (glass / SnO ₂ / a-Si / ZnO / Ag) before forming the second transparent conductive layer 4 for reference. Respectively. In the reference sample, the above-described third transparent conductive layer 6 is not formed. As can be seen from FIG. 5, by forming the second transparent conductive layer 4 having a moth-eye structure, the reflectance is reduced in the visible light region, and more photons can be absorbed by the photovoltaic layer. I understand.

  The embodiments and experimental examples disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Solar cell, 2 Transparent base material, 3rd 1st transparent conductive layer, 4th 2nd transparent conductive layer, 5 photoelectric conversion layer, 6 3rd transparent conductive layer.

Claims (7)

  A transparent base material, a first transparent conductive layer, a second transparent conductive layer, and a photoelectric conversion layer are provided in this order from the light incident side, and the first transparent conductive layer has a texture structure, and the second transparent conductive layer The solar cell, wherein the layer has a moth-eye structure.   The solar cell according to claim 1, wherein the concavo-convex convex portion of the moth-eye structure in the second transparent conductive layer has a height in the range of 10 to 300 nm and a diameter in the range of 10 to 100 nm.   The solar cell according to claim 1, wherein the second transparent conductive layer contains zinc oxide.   The solar cell according to claim 1, wherein the first transparent conductive layer contains tin oxide.   A third transparent conductive layer that is formed of the same material as the second transparent conductive layer and does not have a moth-eye structure is formed between the first transparent conductive layer and the second transparent conductive layer. The solar cell according to any one of claims 1 to 4. A transparent base material, a first transparent conductive layer, a second transparent conductive layer, and a photoelectric conversion layer are provided in this order from the light incident side, and the first transparent conductive layer has a texture structure, and the second transparent conductive layer The layer is a method of manufacturing a solar cell having a moth-eye structure,
The manufacturing method of a solar cell including the process of depositing a said 2nd transparent conductive layer by hold | maintaining the precursor aqueous solution containing a metal source and hexamethylenetetramine at 50-100 degreeC. Forming the first transparent conductive layer with tin oxide, forming the second transparent conductive layer with zinc oxide, and forming the second transparent conductive layer, and then performing a heat treatment at 100 to 300 ° C. The manufacturing method of the solar cell of Claim 6.