JP3618986B2 - Photovoltaic element manufacturing method - Google Patents

Description

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【発明の効果】
本発明の光起電力素子製造方法によれば、光閉込め効果に優れた凹凸を有する酸化亜鉛層を形成することが出来るので、光起電力素子の光電変換効率、短絡光電流、リーク電流といった光導電特性を向上できる。また屋外暴露試験、機械的強度、ＨＨ（高温高湿環境）試験、長時間光照射における耐久性を向上できる。さらに光起電力素子のコストを大幅に低減できる。
【図面の簡単な説明】
【図１】本発明の光起電力素子を示す図
【図２】本発明の酸化亜鉛の製造装置を示す図
【図３】本発明の酸化亜鉛層の断面図
【図４】本発明の酸化亜鉛の連続製造装置を示す図
【図５】水溶液中のサッカロースの含有量と光電変換効率の関係を示す図
【図６】酸化亜鉛層の層厚と光電変換効率の関係を示す図
【図７】酸化亜鉛層の下部層の層厚と光電変換効率の関係を示す図
【図８】酸化亜鉛層の上部層の層厚と光電変換効率の関係を示す図
【図９】水溶液中のデキストリンの含有量と光電変換効率の関係を示す図
【図１０】水溶液中のサッカロースの含有量と光電変換効率の関係を示す図
【図１１】水溶液中のデキストリンの含有量と光電変換効率の関係を示す図
【符号の説明】
１０１ 導電性基板
１０２ 裏面反射層
１０３（ａ） 上部層
１０４（ａ） 下部層
１０３（ｂ） 第１の酸化亜鉛層
１０４（ｂ） 第２の酸化亜鉛層
１０５ 半導体層
１１０ 酸化亜鉛層
２０１ 導電性基板
２０２ 対向電極
２０３ 水溶液
２０５ 電源
２０８ ヒーター
３２０ 鋭い穴
３２１ 緩い穴
３２３ エッチング前の酸化亜鉛層の表面
３２４ エッチング後の酸化亜鉛層の表面
３２５ 第２の酸化亜鉛層堆積後の表面
３２７ エッチング後も残った鋭い穴
４０１ 基板
４０２ 洗浄槽１
４０３ 超音波振動板
４０４ 循環装置
４０５ ヒーター
４０６ 電析槽１
４０７ 循環装置
４０８ 亜鉛電極
４０９ ヒーター
４１０ 定電流電源
４１１ 洗浄槽２
４１２ 循環装置
４１３ 超音波振動板
４１４ ヒーター
４１５ エッチング槽
４１６ 循環装置
４１７ ヒーター
４１８ 洗浄槽３
４１９ 循環装置
４２０ 超音波振動板
４２１ ヒーター
４２２ 電析槽２
４２３ ヒーター
４２４ 循環装置
４２５ 亜鉛電極
４２６ 定電流電源
４２７ 洗浄槽４
４２８ 超音波振動板
４２９ ヒーター
４３０ 循環装置
４３１ 乾燥室
４３２ 搬送ロール
４３３ 送り出しロール
４３４ 巻き取りロール[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for producing a photovoltaic device having a step of forming a zinc oxide layer by electrodeposition.
[0002]
[Prior art]
Conventionally, in order to improve the collection efficiency at a long wavelength of the photovoltaic element, it is known to provide a reflective layer made of metal or the like on the back surface of the semiconductor layer. In addition, by providing an uneven zinc oxide layer between the reflective layer and the semiconductor layer, an optical confinement effect that extends the optical path length of the reflected light and an effect that suppresses excessive current flow during shunting are obtained. It is known that ZnO formed by sputtering is widely used for the zinc oxide layer. Since ZnO is not reduced by hydrogen even when exposed to plasma containing hydrogen such as tin oxide and indium oxide, it is suitable when a semiconductor layer is deposited thereon by CVD.
[0003]
For example, “Optical confinement effect in a-SiGe solar cell on 29p-MF-22 stainless steel substrate” (Autumn 1990), p747 of the 51st Japan Society of Applied Physics Academic Lecture Proceedings, or “a-SiC / a-Si / a-SiGe Multi-Bandgap Stacked Solar Cells With Bandgap Profiling, "Sannomiya et al. , Technical Digest of the International PVSEC-5, Kyoto, Japan, p381, 1990, describes that a short-circuit current increase due to a light confinement effect was achieved by a combination of a reflective layer and a zinc oxide layer.
[0004]
On the other hand, “Electrolyte Optimization for Cathodic Growth of Zinc Oxide Films” Izaki and T.I. Omi, J .; Electrochem. Soc. , Vol. 143, no. 3, March 1996, Japanese Patent Laid-Open No. 8-217443, and the like have reported methods for producing a zinc oxide layer by electrolysis from an aqueous solution containing zinc ions and nitrate ions.
[0005]
[Problems to be solved by the invention]
However, a conventional layer having a light confinement effect is generally formed by resistance heating, electron beam vacuum deposition, sputtering, ion plating, CVD, or the like. For this reason, there are problems such as a high production cost of the target material, a vacuum process, a high depreciation cost of the vacuum apparatus, and a low material utilization efficiency. Therefore, when these technologies are used, the cost of the photovoltaic device becomes extremely high, and this is a great barrier to industrial application of solar cells.
[0006]
Moreover, although the zinc oxide layer formed by electrolysis from the aqueous solution containing the zinc ions and acetate ions can be formed at a low cost, it has the following problems.
[0007]
(1) In particular, when the current density is increased or the concentration of the solution is increased, abnormal growth having a shape such as a needle shape, a spherical shape, or a resin shape exceeding micron order is easily generated on the deposited film. When this zinc oxide layer is used as a part of the photovoltaic device, these abnormal growths cause a shunt path of the photovoltaic device.
[0008]
(2) The size of the zinc oxide crystal grains tends to vary, and there is a problem in uniformity when the area is increased.
[0009]
(3) Adhesion on the substrate was inferior to those formed by resistance heating, electron beam vacuum deposition, sputtering, ion plating, CVD, or the like.
[0010]
(4) Only a thin film having a smooth film thickness was formed, and a method for forming a zinc oxide film having an uneven shape with a light confinement effect was unknown.
[0011]
The present invention provides a method of forming a zinc oxide layer suitable for application to a light confinement layer of a photovoltaic device by electrodeposition.
[0012]
[Means for Solving the Problems]
A method for manufacturing a photovoltaic device for solving the above-described problem is to supply current between a conductive substrate immersed in an aqueous solution containing at least nitrate ions and zinc ions, and an electrode immersed in the solution. A step of forming a zinc oxide layer (first zinc oxide layer) on the conductive substrate, a step of etching the zinc oxide layer, and a step of forming a semiconductor layer. And the first aqueous solution contains carbohydrates Manufacturing method.
[0013]
You may have the process of forming a 2nd zinc oxide layer similarly to the said zinc oxide layer between the process of etching and the process of forming the said semiconductor layer.
[0014]
By containing carbohydrate in the aqueous solution, abnormal growth of zinc oxide crystal grains can be suppressed, so that leakage current of the element can be reduced and photoelectric conversion efficiency and yield can be improved.
[0015]
By providing a metal layer made of a metal having a high reflectance on the support, the reflectance as a substrate can be increased, and a photovoltaic element having a higher light conversion efficiency can be produced.
[0016]
As the metal layer, Au, Ag, Cu, CuMg (an alloy of Cu and Mg), Al, or the like can be used. Al is suitable for the metal layer because it is inexpensive, but since Al dissolves in an aqueous solution containing nitrate ions and zinc ions, it is difficult to deposit zinc oxide on Al. In this case, it is preferable to previously form a transparent and conductive intermediate layer on Al.
[0017]
It is desirable to use acetic acid or an acetic acid aqueous solution for etching.
[0018]
The zinc oxide layer formed on the substrate consists of a fine crystal, smooth surface, a lower layer with excellent adhesion to the substrate, and an upper layer with a large crystal grain and uneven surface and a large light confinement effect. It is preferable to have a laminated structure. Such a zinc oxide layer can achieve both adhesion to the substrate and effective light confinement. These layers can be formed by making the formation temperature, current density, or aqueous solution concentration different from each other.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
(Configuration of photovoltaic element)
FIG. 1 is a schematic cross-sectional view of the photovoltaic device of the present invention. On the conductive substrate 101, a back reflective layer 102 mainly composed of gold, silver, copper, copper magnesium, or aluminum, a zinc oxide layer 110 made of zinc oxide, a semiconductor layer 105, an upper transparent electrode 106, and a collecting electrode 107 are stacked.
[0020]
The zinc oxide layer 110 in FIG. 1A includes a lower layer 103 (a) and an upper layer 104 (a). The surface of the upper layer 104 (a) is etched to form irregularities. The upper layer is preferably formed at a temperature of 80 ° C. or higher. Further, it is desirable that the current density for forming the lower layer is higher than that of the upper layer. Further, it is desirable that the concentration of nitrate ions and zinc ions for forming the lower layer is higher than that of the upper layer.
[0021]
The zinc oxide layer 110 in FIG. 1B includes a zinc oxide layer 103 (b) and a second zinc oxide layer 104 (b). Others are the same as in FIG. The surface of the zinc oxide layer 103 (b) is etched to form irregularities. Thereafter, a second zinc oxide layer 104 (b) is formed. The zinc oxide layer 103 (b) may have a two-layer structure as shown in FIG.
[0022]
(Method for forming zinc oxide layer)
Next, a method for forming a zinc oxide layer made of zinc oxide in the photovoltaic element of the present invention is shown in FIG.
[0023]
First, a zinc nitrate aqueous solution 203 having a predetermined concentration is prepared in a container 204, the aqueous solution is thoroughly stirred using a magnetic stirring bar 209, and the aqueous solution is heated to a predetermined temperature using a heater 208. Next, the conductive substrate 201 to which the counter electrode 202 and the insulating tape 206 are attached is connected to a power source 205 and a load resistor 207 to form a circuit through an aqueous solution, and a voltage is applied to the circuit in a constant current mode. Then, a transparent zinc oxide thin film is deposited on the conductive substrate surface on the negative electrode side.
[0024]
When the zinc oxide layer having a predetermined thickness is formed, voltage application is interrupted, and the conductive substrate on which the zinc oxide layer has been formed is taken out and washed thoroughly with pure water.
[0025]
Here, when zinc nitrate is used as a supply source of nitrate ions and zinc ions, the concentration of the aqueous zinc nitrate solution is preferably 0.05 mol / l or more and 1.0 mol / l or less. The temperature is preferably 50 ° C. or higher. Furthermore, the current density on the surface of the conductive substrate is 0.1 mA / cm. ² 100 mA / cm ² The following is desirable.
[0026]
These formation conditions differ depending on the type, cross-sectional shape, and crystal state of the back reflective layer, and cannot be determined uniquely.However, in general, the higher the zinc nitrate concentration, the larger the zinc oxide crystal grains and the unevenness on the surface. Easy to do. Also, the lower the formation temperature, the larger the zinc oxide crystal grains. Furthermore, the surface current unevenness tends to decrease as the current density increases, but the formation speed increases.
[0027]
(etching)
FIG. 2B shows an apparatus for etching the surface of the zinc oxide layer. Since zinc oxide is an amphoteric oxide, it is soluble in both acids and alkalis. First, an acidic aqueous solution such as acetic acid or an alkaline aqueous solution 213 such as aqueous ammonia is put in a container 214, and the conductive substrate 212 on which the zinc oxide layer is formed is immersed in this aqueous solution, and the zinc oxide layer made of zinc oxide is etched.
[0028]
As the solution for etching, an acidic aqueous solution or an alkaline aqueous solution can be used. A weak acid such as acetic acid, a weak alkali such as ammonia water, a strong acid such as nitric acid, or a strong alkali such as potassium hydroxide is sufficient with water. It is desirable to use it diluted. The acidic aqueous solution preferably has a hydrogen ion concentration pH of 2 or more and 5 or less, and the alkaline aqueous solution preferably has a hydrogen ion concentration pH of 9 or more and 12 or less. The temperature during etching is preferably from room temperature to 50 ° C. The etching time is preferably 5 to 30 seconds when acetic acid is used.
[0029]
In an aqueous solution containing a large amount of sulfate ion, sulfide ion, or hydroxide ion in the etching solution, zinc sulfate, zinc sulfide, zinc hydroxide, or the like may precipitate in the zinc oxide layer and cause a decrease in yield. The inventors have found that acetic acid or an aqueous acetic acid solution is particularly suitable as an etching solution. By using acetic acid, irregularities suitable for light confinement can be easily formed, and it is not necessary to take special acid resistance measures for the apparatus.
[0030]
(Cross sectional shape of zinc oxide layer)
FIG. 3A shows a cross-sectional shape of a zinc oxide layer made of zinc oxide before etching, in which relatively sharp holes 320 and loose holes 321 are formed. In this state, the cross-sectional shape is not suitable for the optical confinement layer of the photovoltaic element. Also, the sharp hole 320 is not desirable because it causes a short circuit of the element. In the present invention, on the contrary, this sharp hole is actively used to obtain a cross-sectional shape suitable for the optical confinement layer. That is, when a zinc oxide layer having a sharp hole is etched, the periphery of the sharp hole is eroded and a suitable unevenness as shown in FIG. 3B can be obtained. Here, the hole refers to a region where the angle formed by the surface of the zinc oxide layer and the horizontal plane is 70 ° or more.
[0031]
The diameter of the hole before etching is preferably about 0.05 to 0.3 μm. Hole density is 100μm ² 100 to 1000 per piece is preferable.
[0032]
Etching can still leave a sharp hole 327. Therefore, as described above, the second zinc oxide layer 304 may be formed on the first zinc oxide layer 303 by electrodeposition to fill the sharp hole 327 (FIG. 3C). The current density for forming the second zinc oxide layer can be deposited so as to fill the sharp hole 327 more effectively by increasing the current density than that of the first zinc oxide layer. This is because film deposition is made more uniform as the current density increases. The surface roughness Ra before etching is 50 to 300 mm, and Ra after etching is 600 mm or more.
[0033]
The second zinc oxide layer 304 may be formed by a conventional sputtering method.
[0034]
(Conditions for forming the zinc oxide layer)
The hole in the zinc oxide layer can be suitably obtained by laminating a layer formed at a temperature of about 85 ° C. on a layer formed at a temperature of about 65 ° C. Alternatively, it can be obtained by forming a layer on a layer formed under certain conditions by reducing the current density and decreasing the zinc nitrate concentration.
[0035]
Since zinc oxide formed at a low temperature (70 ° C. or lower) is dense, etching occurs only uniformly, and the uneven shape of the formation surface does not change greatly. However, zinc oxide formed at a high temperature (80 ° C. or higher) is rough because the crystal grows in a direction perpendicular to the surface of the conductive substrate, and thus non-uniform etching is likely to occur. The surface shape as shown in FIG. It is thought that it becomes.
[0036]
Further, by controlling the layer thickness of the upper layer, it is possible to control the depth of the surface irregularities after etching. By this manufacturing method, the surface unevenness shape of the zinc oxide layer made of zinc oxide can be further optimized, so that light confinement or light scattering is further improved. Therefore, the quality of the photovoltaic element can be further improved.
[0037]
Further, by forming the lower layer at a high current density, the surface to be formed becomes almost flat, crystals grow in the horizontal direction with respect to the surface of the conductive substrate, and deep and large holes are controlled with relatively few. By forming the upper layer at a low current density and a low solution concentration, the crystal grows in a direction perpendicular to the surface of the conductive substrate and is rough, so uneven etching is likely to occur, as shown in FIG. It becomes a surface shape.
[0038]
(Addition of carbohydrates)
In the production method of the present invention, abnormal growth of crystals can be suppressed by adding a carbohydrate to an aqueous solution. If there is a plate-like abnormal growth, the semiconductor layer formed at the location where the abnormal growth occurs is locally thin, an excessive leakage current is generated, and the function as an element cannot be performed.
[0039]
Examples of the carbohydrate include monosaccharides such as glucose (glucose) and fructose (fructose), disaccharides such as maltose (malt sugar) and saccharose (sucrose), polysaccharides such as dextrin and starch, or mixtures thereof. I can do it.
[0040]
When sucrose is added, 1 to 300 g / l, or when dextrin is added, 0.001 to 10 g / l is desirable. If it is below the desired range, the effect of suppressing abnormal growth is small. Conversely, if it exceeds the desired range, the formed zinc oxide film becomes almost flat, so the number of holes necessary to create irregularities is reduced.
[0041]
Industrially, it is advantageous to increase the current density, but the current density is 5 mA / cm. ² When the zinc oxide layer is formed by increasing the above, standing abnormal plate-like growth having a size of 10 μm or more becomes conspicuous. However, such abnormal growth can be almost eliminated by adding carbohydrate to the aqueous solution. This manufacturing method can improve the yield of photovoltaic elements.
[0042]
(Aluminum reflective layer)
Aluminum is the most promising metal for the back reflective layer of photovoltaic elements because it has a high reflectivity in light with a wavelength of 600 nm-1000 nm and does not cause electrochemical migration. However, as described above, it is difficult to electrochemically grow (electroplate) zinc oxide directly on aluminum in an aqueous solution.
[0043]
Therefore, it is preferable to provide an extremely thin intermediate layer (preferably having a thickness of 0.01 μm or more) on aluminum. This intermediate layer is transparent in light having a wavelength of 600 nm to 1000 nm and has a certain level of (10 ^-8 It must be conductive (approximately Ωcm or higher). For example, tin oxide (SnO ₂ ), Indium oxide (In ₂ O ₃ ), ITO (SnO ₂ + In ₂ O ₃ ), Zinc oxide (ZnO), indium zinc oxide, tin zinc oxide and the like.
[0044]
These oxides are formed by sputtering, CVD, or vacuum deposition. A zinc oxide layer made of zinc oxide can be formed on these intermediate layers by the method of the present invention. Since the concavo-convex shape is optimized by the etching process, light confinement or light scattering is sufficiently performed even with light having a wavelength of 600 nm to 1000 nm. Therefore, the photovoltaic device of the present invention has high quality and low power cost.
[0045]
(Zinc oxide layer thickness)
The total thickness of the zinc oxide layer is preferably 0.7 μm or more and 3 μm or less. When the lower layer and the upper layer are formed, the lower layer is preferably 0.5 μm or more, and the upper layer is preferably 0.2 μm or more.
[0046]
This is because if the thickness of the zinc oxide layer is 0.7 μm or less, the generation density of holes required for the etching process becomes extremely small. Moreover, it is because it does not contribute much to the confinement effect and scattering of light having a wavelength of 600 nm to 1000 nm.
[0047]
If the lower layer is 0.5 μm or less, the denseness is insufficient, and unnecessary holes are easily formed during the etching process. If the upper layer is 0.2 μm or less, the generation density of the holes necessary for the etching process is extremely high. It is small, and the depth of the surface unevenness after the etching process becomes insufficient.
[0048]
When the thickness of the zinc oxide layer is 3 μm or more, the density of occurrence of abnormal plate-like growth increases. Moreover, it is disadvantageous in terms of industrial and cost to make the film thicker than necessary.
[0049]
When the first and second zinc oxide layers are formed, the thickness of the first zinc oxide layer is 0.5 μm or more, the second is 0.05 μm or more, and the two layers together are 0.7 μm or more and 3 μm or less. Is desirable. If the thickness of the second zinc oxide layer is 0.05 μm or less, the deep hole cannot be completely filled.
[0050]
Hereinafter, other components of the present invention will be described.
[0051]
(Conductive substrate)
The conductive substrate used in the present invention may be a single substrate, or may be a single substrate or a plurality of thin films formed on the substrate. The substrate may be electrically insulating as long as one surface of the substrate has conductivity.
[0052]
Examples of the conductive material include metals such as Cu, Ni, Cr, Fe, Al, Cr, Mo, Nb, Ta, V, Ti, and Rh, or alloys thereof, and these can be used alone as a substrate. In particular, stainless steel, Fe, and the like are suitable from the viewpoint of processability, strength, chemical stability, and price.
[0053]
Examples of the insulating base material include polyester, polyethylene, polycarbonate, cellulose acetate, polypropylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyamide, and other synthetic resins, or glass and ceramics. The thin film which consists of said electroconductive material is formed in at least one surface.
[0054]
In order to use these materials as a substrate, a sheet shape or a roll shape in which a belt is wound around a cylindrical body is desirable. When a substrate is formed by forming a thin film on a substrate, it is formed by a vacuum deposition method, a sputtering method, a screen printing method, a dipping method, a plasma CVD method, an electroplating method, an electroless plating method, or the like.
[0055]
Also, HNO is used to form irregularities on the substrate surface. ₃ , HF, HCl, H ₂ SO ₄ The substrate surface may be etched or rubbed using an acidic solution such as.
[0056]
Further, it is desirable that the surface is cleaned with a surface active agent or an organic substance in order to prevent peeling of the back reflective layer and the zinc oxide layer.
[0057]
(Back reflective layer)
The back reflective layer used in the present invention may be composed of a single layer or a plurality of layers. Mainly composed of gold, silver, copper, copper magnesium, or aluminum. In any case, the film thickness is preferably 0.05 μm or more and 0.5 μm or less. A film thickness of 0.05 μm or less is disadvantageous because the reflectance decreases. Further, if the film thickness is 0.5 μm or more, it is disadvantageous in terms of cost.
[0058]
As the method for forming the back reflective layer, it is desirable to use a vacuum deposition method, a sputtering method, or a method of electrochemical deposition from an aqueous solution (plating method). The surface of the back reflective layer may be smooth or uneven. When the back surface reflection layer is formed by sputtering, the adhesion with the conductive substrate is improved by making the substrate temperature 150 ° C. or higher and making it uneven.
[0059]
(Middle layer)
When aluminum is used for the back reflective layer used in the present invention, since the zinc oxide layer of the present invention cannot be directly formed thereon, a transparent and conductive layer as an intermediate layer is formed on the aluminum layer. To form. As the intermediate layer, zinc oxide, tin oxide, indium oxide, ITO or the like is suitable.
[0060]
In any case, the film thickness is preferably 0.01 μm or more. This is because if the film thickness is 0.01 μm or less, the film may have an island shape. As the method for forming the back reflective layer, it is desirable to use a vacuum deposition method, a sputtering method, or a method of electrochemical deposition from an aqueous solution (plating method).
[0061]
(Semiconductor layer)
Examples of the semiconductor layer material include a pn junction, a pin junction, a Schottky junction, and a heterojunction. Examples of the semiconductor material include hydrogenated amorphous silicon, hydrogenated amorphous silicon germanium, and hydrogenated amorphous silicon. Carbide, microcrystalline silicon or polycrystalline silicon can be used.
[0062]
In particular, amorphous or microcrystalline Si, C, Ge, or alloys thereof are suitable for continuous formation on a long substrate. At the same time, hydrogen and / or halogen atoms are contained. Its preferred content is 0.1 to 40 atomic%. Further, oxygen, nitrogen, etc. may be contained. These impurity concentrations are 5 × 10 ¹⁹ cm ^-3 The following is desirable. Furthermore, a p-type semiconductor contains a group III element, and a n-type semiconductor contains a group V element.
[0063]
In the case of the stack cell, the pin junction i-type semiconductor layer close to the light incident side has a wide band gap, and the band gap is preferably narrowed as the far pin junction is formed. In addition, it is preferable that the minimum value of the band gap be closer to the p layer than the center of the film thickness inside the i layer.
[0064]
As the doped layer on the light incident side, a crystalline semiconductor with little light absorption or a semiconductor with a wide band gap is suitable.
[0065]
In order to form the semiconductor layer, a microwave (MW) plasma CVD method or a radio frequency (RF) plasma CVD method is suitable.
[0066]
(Transparent electrode)
The transparent electrode can also serve as an antireflection film by appropriately setting its film thickness.
[0067]
Transparent electrodes are ITO, ZnO, InO ₃ A material such as vapor deposition, CVD, spraying, spin-on, and immersion are formed. You may contain the substance which changes electrical conductivity in these compounds.
[0068]
(Collector electrode)
The current collecting electrode is provided to improve current collecting efficiency. As the manufacturing method, there are a method of forming a metal of an electrode pattern by sputtering using a mask, a method of printing a conductive paste or a solder paste, and a method of fixing a metal wire with a conductive paste.
[0069]
In addition, a protective layer may be formed on both surfaces of the photovoltaic element as necessary. At the same time, a reinforcing material such as a steel plate may be used in combination.
[0070]
【Example】
(Example 1)
0.8 μm of Ag was vapor-deposited on a stainless steel substrate (SUS430 10 × 10 cm, thickness 0.2 mm), a zinc oxide layer was formed under the conditions shown in Table 1, and etched with acetic acid. Three pin junctions were formed as semiconductor layers, the lower two pin junctions were formed by microwave CVD, and the uppermost pin junction was formed by high-frequency CVD. The lower two pin junctions were a-SiGe, and the i layer of the uppermost pin junction was a-Si. The p layer of the lower two pin junctions was μc-Si. The semiconductor layer was formed under the conditions shown in Table 6.
[0071]
Furthermore, ITO was formed as an upper transparent electrode layer by sputtering with a thickness of 0.08 μm, and a silver-coated copper wire as a collecting electrode was heat-pressed on the ITO with a carbon paste.
[0072]
(Comparative Example 1a)
A zinc oxide layer was formed in the same manner as in Example 1 except that a conventional sputtering method was used.
[0073]
(Comparative Example 1b)
It was produced in the same manner as in Example 1 except that etching was not performed.
[0074]
(Evaluation)
The initial photoelectric conversion efficiency and the initial short circuit current were measured using a solar simulator (AM1.5, 100 mW / cm 2, surface temperature 25 ° C.).
[0075]
An HH test (high temperature and high humidity test) was performed as an acceleration test. The photovoltaic device was put into an environmental test box and left at a temperature of 86 ° C. and a humidity of 85% for 150 hours. Next, the environmental test box was set at a temperature of 25 ° C. and a humidity of 50% and left for 1 hour to take out. . Similarly, the photoelectric conversion efficiency and short circuit current of the photovoltaic device were measured.
[0076]
As a light irradiation test, it was exposed to a simulator (AM 1.5, 100 mW / cm 2, surface temperature 50 ° C.) for 800 hours, and the photoelectric conversion efficiency and the short-circuit photocurrent were measured.
[0077]
The evaluation results of Example 1 with reference to Comparative Examples 1a and 1b are the initial photoelectric conversion efficiency of 1.14 times and 1.07 times, the initial short circuit current of 1.15 times and 1.13 times, respectively. Photoelectric conversion efficiency after high temperature and high humidity test 1.08 times, 1.06 times, short circuit current 1.12 times, 1.10 times, photoelectric conversion efficiency after light irradiation test 1.04 times, 1.03 It was found to be twice as good.
[0078]
(Example 2)
The photovoltaic element shown in FIG. 1 (a) in which the zinc oxide layer was composed of two layers, an upper layer and a lower layer, was prepared. The conditions for forming the zinc oxide layer were the same as in Example 1 except that the conditions were as shown in Table 2.
[0079]
When the same evaluation as in Example 1 was performed, it was found that the element of Example 2 was superior to the element of Comparative Example 1. Further, after the high temperature and humidity test and the light irradiation test, the photovoltaic device was placed in a dark place, a reverse bias of 1.1 V was applied, and the leakage current was measured. In Example 2, the leakage current was about 1/10 compared to Comparative Example 1.
[0080]
(Example 3)
A long sheet was used as a substrate, and a zinc oxide layer was formed on the substrate by a roll-to-roll method. Prior to that, an intermediate layer of 0.05 μm of aluminum and 0.1 μm of zinc oxide was formed on a long SUS430BA (thickness of 0.15 mm) by sputtering using a Roll-to-Roll method.
[0081]
Subsequently, a zinc oxide layer was formed using the apparatus shown in FIG. The apparatus will now be described. Reference numeral 401 denotes a long substrate having flexibility such as stainless steel, and an insulating tape (not shown) is pasted on the back surface. Reference numeral 433 denotes a feed roll in which the substrate is wound in a roll shape, and reference numeral 434 denotes a take-up roll for winding the substrate. The substrate is wound from the feed roll through the respective tanks through a number of transport rollers 432 to the take-up roll. It will be. In this embodiment, each roller has a diameter of 40 cm or more in order to prevent plastic deformation of the substrate.
[0082]
Reference numeral 402 denotes a cleaning tank that performs ultrasonic organic cleaning, to which a circulation device 404 including a filter for removing dust is connected. Inside the bathtub, there is an ultrasonic vibration plate 403 and a heater 405.
[0083]
Reference numeral 406 denotes an electrodeposition tank 1 for forming a first zinc oxide layer, to which a circulation device 407 having a filter for removing dust is also connected. A zinc electrode 408 and a heater 409 are provided inside the bathtub, and a fixed electrode is provided outside. The current power supply is connected. The electrodeposition tank 1 is filled with a zinc nitrate aqueous solution to which 13 g / l of sucrose is added, and the circulation device 407 has a system for monitoring the concentration of the zinc nitrate aqueous solution and adding zinc nitrate as needed when the concentration decreases.
[0084]
Reference numeral 411 denotes a cleaning tank 2 that performs ultrasonic pure water cleaning, to which a circulation device 412 having a built-in filter for removing dust is connected, and an ultrasonic diaphragm 413 and a heater 414 are provided inside the bathtub.
[0085]
Reference numeral 415 denotes an etching tank for etching the surface of the first zinc oxide layer, which is connected to a circulation device 416 having a filter for removing dust, and has a heater 417. The inside of the etching tank 415 is filled with 0.008 mol / l acetic acid aqueous solution, and the circulation device 416 has a function of monitoring the concentration of the acetic acid aqueous solution and has a system for adding acetic acid when the concentration decreases. .
[0086]
Reference numeral 418 denotes the same washing tank 3 as 411. Reference numeral 422 denotes a washing tank 4 that replaces pure water with alcohol or the like, to which a circulation device 424 that also contains a filter for removing dust is connected, and an ultrasonic diaphragm 423 is provided inside the bathtub. Reference numeral 431 denotes a drying chamber for performing hot air drying.
[0087]
The method of using this apparatus will be described below. First, each tank is filled with a predetermined solution, and a circulation device, a heater, and ultrasonic vibration are made to function. The heater is set so that the temperature of the cleaning tank 1 is the temperature of the electrodeposition tank 1, the temperature of the cleaning tank 2 is the temperature of the etching tank, and the temperature of the cleaning tank 3 is about 80 ° C.
[0088]
The substrate fed from the feed roll is wound on the take-up roll through the cleaning tank 1, the electrodeposition tank 1, the cleaning tank 2, the etching tank, the cleaning tank 3, the cleaning tank 4, and the drying chamber via each transport roller. It is done.
[0089]
The constant current power supply 410 is set to have a predetermined current density, and continuous formation of the zinc oxide layer is started. When the formation of the zinc oxide layer on the 800 m substrate is completed, the conveyance is stopped, the constant current power source, the heater, and the ultrasonic vibration are turned off, and the substrate on which the zinc oxide layer is formed is taken out. Table 3 shows the conditions for forming the zinc oxide layer.
[0090]
Next, using the Roll-to-Roll method, a semiconductor layer is formed on the zinc oxide layer by a CVD method, and ITO is formed by a 0.08 μm sputtering method. Under the conditions shown in Table 6, three pin junctions were formed.
[0091]
Rolled solar cell taken out 30x30cm ² Next, a collector electrode similar to that of Example 1 was attached, and four solar cells were connected in series via a bus bar, and a bypass diode was connected in parallel with each solar cell. Next, EVA, nylon resin, EVA, glass nonwoven fabric, serialized solar cell, glass nonwoven fabric, EVA, glass nonwoven fabric, EVA, glass nonwoven fabric, and fluororesin are superimposed and heated on a support substrate having a thickness of 0.3 mm. Vacuum sealed (lamination).
[0092]
35x130cm created as above ² When the solar cell module of the size was measured and tested in the same manner as in Example 1, the initial characteristics, high temperature and high humidity test, and light irradiation test were excellent characteristics.
[0093]
Furthermore, the torsion test of the solar cell JIS C 8917 was performed. “Torsion”, in which three corners were fixed and one corner was displaced by 3 cm, was repeated 50 times for each corner. A similar “twist” was performed on all corners. When photoelectric conversion efficiency, short-circuit photocurrent, leakage current, and low illuminance open voltage were measured, there was almost no deterioration due to the torsion test.
[0094]
(Example 4)
The zinc oxide layer consists of two layers, an upper layer and a lower layer. The current density for forming the upper layer is lower than the current density for forming the lower layer, and the upper layer is formed. The photovoltaic element was prepared by lowering the concentrations of nitrate ions and zinc ions of each of the lower concentrations than the concentrations in forming the lower layer. A photovoltaic element similar to that in Example 1 was prepared except that the conditions for forming the zinc oxide layer in Example 1 were as shown in Table 4. When the same measurement and test as in Example 1 were performed, it was found that the photovoltaic element of Example 4 was superior to the photovoltaic element of Example 1.
[0095]
(Example 5)
A photovoltaic device was prepared in the same manner as in Example 3 using the apparatus shown in FIG. The zinc oxide layer consists of two layers, an upper layer and a lower layer. The current density for forming the upper layer is lower than the current density for forming the lower layer, and the upper layer is formed. The photovoltaic element was made by making the concentration of nitrate ion and zinc ion lower than the concentration at the time of forming the lower layer. A photovoltaic device example 5 similar to that of example 3 was prepared except that the conditions for forming the zinc oxide layer in Example 3 were as shown in Table 5. When the same measurement and test as in Example 3 were performed, it was found that the photovoltaic element of Example 5 was as excellent as the photovoltaic element of Example 3.
[0096]
(Example 6)
A photovoltaic device was prepared and tested and evaluated in the same manner as in Example 1 except that a 0.0005 mol / l nitric acid aqueous solution was used as the aqueous solution 2 to be etched. Was found to be as excellent as the photovoltaic element of Example 1.
[0097]
(Example 7)
A photovoltaic device was prepared and tested and evaluated in the same manner as in Example 1 except that 0.005 mol / l hydrochloric acid aqueous solution was used as the aqueous solution 2 to be etched. Was found to be as excellent as the photovoltaic element of Example 1.
[0098]
(Example 8)
A photovoltaic device was prepared and tested and evaluated in the same manner as in Example 1 except that 0.1 mol / l sodium acetate aqueous solution was used as the aqueous solution 2 to be etched. The device was found to be as good as the photovoltaic device of Example 1.
[0099]
Example 9
An experiment was conducted in which the saccharose content in the aqueous solution was changed. In Example 2, the saccharose content in the aqueous solution was changed from 0 to 800 g / l to produce a photovoltaic device similar to that in Example 2, and the photoelectric conversion efficiency (initial value) was measured. The results are shown in FIG. As shown in FIG. 5, the photoelectric conversion efficiency was maximized when the saccharose content was 1 g / l or more and 300 g / l or less.
[0100]
When the cross section of the zinc oxide layer was observed with an SEM (magnification 1000 times), there were many abnormal plate-like growths at sucrose of 1 g / l or less. The leakage current was increased and the photoelectric conversion efficiency was lowered. Conversely, when the saccharose was 300 g / l or more, the shape obtained by etching the zinc oxide layer was too flat to perform light confinement or light diffusion, and the photoelectric conversion efficiency was lowered.
[0101]
(Example 10)
An experiment was conducted in which the thickness of the zinc oxide layer was changed. When a photovoltaic element similar to that of Example 1 was prepared by changing the thickness of the zinc oxide layer from 0.2 μm to 3.7 μm in Example 1, the thickness of the zinc oxide layer was 0 as shown in FIG. The photoelectric conversion efficiency was maximized when the thickness was 7 μm or more and 3 μm or less.
[0102]
When the cross section of the zinc oxide layer was observed with an SEM, when the thickness of the zinc oxide layer was 0.7 μm or less, the generation density of deep holes necessary for the etching treatment was extremely small, and the number of irregularities was small. The short circuit current was reduced and the photoelectric conversion efficiency was lowered. On the contrary, when the thickness of the zinc oxide layer is 3 μm or more, the occurrence density of standing abnormal plate-like growth is increased, the leakage current is increased, and the photoelectric conversion efficiency is lowered.
[0103]
(Example 11)
An experiment was conducted in which the thickness of the lower layer of the zinc oxide layer was changed. A photovoltaic device similar to that of Example 2 was prepared by changing the thickness of the upper layer in Example 2 to 0.2 μm and changing the thickness of the lower layer from 0.2 μm to 1.2 μm. Thus, when the film thickness of the lower layer of the zinc oxide layer is 0.5 μm or more, the photoelectric conversion efficiency is maximized.
[0104]
When the cross section of the zinc oxide layer was observed with an SEM, if the thickness of the lower layer of the zinc oxide layer was 0.5 μm or less, the denseness was insufficient, and unnecessary deep holes were likely to occur during the etching process, resulting in leakage current. It became large and the photoelectric conversion efficiency fell.
[0105]
(Example 12)
An experiment was conducted in which the thickness of the upper layer of the zinc oxide layer was changed. A photovoltaic element similar to that of Example 2 was prepared by changing the thickness of the lower layer in Example 2 to 0.5 μm and changing the thickness of the upper layer from 0.05 μm to 0.75 μm. Thus, when the layer thickness of the upper layer of the zinc oxide layer was 0.2 μm or more, the photoelectric conversion efficiency was maximized.
[0106]
When the cross section of the zinc oxide layer was observed with an SEM, if the thickness of the upper layer of the transparent conductive layer was 0.2 μm or less, the generation density of deep holes necessary for the etching process was extremely small, and after the etching process, The depth of the surface unevenness became insufficient, and the photoelectric conversion efficiency was lowered because the short-circuit current was reduced because it did not contribute much to the confinement effect and scattering of light having a wavelength of 600 nm to 1000 nm.
[0107]
(Example 13)
An experiment was conducted in which the dextrin content in the aqueous solution was changed. In Example 2, the dextrin content in the aqueous solution was changed from 0 to 100 g / l to produce a photovoltaic device similar to that in Example 2. As shown in FIG. 9, the dextrin content was 0.001 g / l or more. Photoelectric conversion efficiency was maximized at 10 g / l or less.
[0108]
When the cross section of the zinc oxide layer was observed with an SEM, there were many abnormal plate-like growths when the dextrin was 0.001 g / l or less. The leakage current was increased and the photoelectric conversion efficiency was lowered. On the other hand, when the dextrin was 10 g / l or more, the shape obtained by etching the zinc oxide layer was too flat to perform light confinement or light diffusion, so that the photoelectric conversion efficiency was lowered.
[0109]
(Example 14)
In Example 3, a photovoltaic element having an intermediate layer made of tin oxide was produced. A photovoltaic device was produced by the same method as in Example 3 except that an intermediate layer having a thickness of 0.12 μm was formed by sputtering. The photovoltaic device had excellent characteristics as in the photovoltaic device of Example 3. It was.
[0110]
(Example 15)
A photovoltaic device having a back reflective layer made of copper was produced. A photovoltaic device similar to that of Example 2 was prepared except that the back surface reflective layer made of copper was prepared by an electrodeposition method. As a result, it was found that the photovoltaic device was as excellent as the photovoltaic device of Example 2.
[0111]
(Example 16)
Ag was vapor-deposited on a stainless steel substrate (SUS430 10 × 10 cm, thickness 0.2 mm), a first zinc oxide layer was formed under the conditions in Table 7, etched with acetic acid, and a second zinc oxide layer was further formed. . Three pin junctions were formed as semiconductor layers, the lower two pin junctions were formed by microwave CVD, and the uppermost pin junction was formed by high-frequency CVD. The lower two pin junctions were a-SiGe, and the i layer of the uppermost pin junction was a-Si. The p layer of the lower two pin junctions was μc-Si. The semiconductor layer was formed under the conditions shown in Table 11.
[0112]
Furthermore, ITO was formed as an upper transparent electrode layer by sputtering with a thickness of 0.08 μm, and a silver-coated copper wire as a collecting electrode was heat-pressed on the ITO with a carbon paste.
[0113]
(Comparative Example 2)
It was prepared in the same manner as in Example 16 except that the zinc oxide layer was formed by a conventional sputtering method.
[0114]
The evaluation result of Example 16 with reference to Comparative Example 2 is that the initial photoelectric conversion efficiency is 1.15 times, the initial short circuit current is 1.16 times, and the photoelectric conversion efficiency after the high temperature and high humidity test is 1.07 times. It was found that the short circuit current was 1.10 times and the photoelectric conversion efficiency after the light irradiation test was 1.02 times better.
[0115]
(Example 17)
The first zinc oxide layer was composed of two layers, an upper layer and a lower layer, and a photovoltaic device having a second zinc oxide layer was produced. The conditions for forming the zinc oxide layer were the same as in Example 16 except that the conditions were as shown in Table 8.
[0116]
When the same evaluation as in Example 1 was performed, it was found that the element of Example 2 was superior to the element of Comparative Example 1. Further, after the high temperature and humidity test and the light irradiation test, the photovoltaic device was placed in a dark place, a reverse bias of 1.1 V was applied, and the leakage current was measured. In Example 2, the leakage current was about 1/10 compared to Comparative Example 1. Further, the uniformity of the zinc oxide film was superior to that of Example 16, and the long wavelength sensitivity as a photovoltaic element was excellent.
[0117]
(Example 18)
A long sheet was used for the substrate, and it was formed by the Roll-to-Roll method. First, an intermediate layer of 0.05 μm aluminum and 0.1 μm zinc was formed on a long SUS430BA (thickness 0.15 mm) by sputtering using a roll-to-roll method.
[0118]
Subsequently, after the first zinc oxide layer was formed and etched using the apparatus of FIG. 4C, a second zinc oxide layer was further formed under the conditions shown in Table 9. The semiconductor layer was formed under the conditions shown in Table 11. When a solar cell module having a size of 35 × 130 cm 2 prepared in the same manner as in Example 16 was measured and tested in the same manner as in Example 16, the initial characteristics, high temperature and high humidity test, and light irradiation test were all excellent characteristics.
[0119]
Furthermore, the torsion test of the solar cell JIS C 8917 was performed. “Torsion”, in which three corners were fixed and one corner was displaced by 3 cm, was repeated 50 times for each corner. A similar “twist” was performed on all corners. When the photoconductive characteristics, leakage current, and low illuminance open-circuit voltage were measured, there was little deterioration.
[0120]
(Example 19)
The zinc oxide layer consists of two layers, an upper layer and a lower layer. The current density for forming the upper layer is lower than the current density for forming the lower layer, and the upper layer is formed. The photovoltaic element was prepared by lowering the concentrations of nitrate ions and zinc ions of each of the lower concentrations than the concentrations in forming the lower layer. A photovoltaic element similar to that of Example 1 was prepared except that the conditions for forming the zinc oxide layer in Example 16 were as shown in Table 10. When the same measurement and test as in Example 1 were performed, it was found that the photovoltaic element of Example 19 was superior to the photovoltaic element of Example 16.
[0121]
(Example 20)
A photovoltaic device was prepared and tested and evaluated in the same manner as in Example 16 except that a 0.0005 mol / l nitric acid aqueous solution was used as the aqueous solution 2 to be etched. The photovoltaic device of Example 20 was tested and evaluated. Was found to be as excellent as the photovoltaic element of Example 16.
[0122]
(Example 21)
A photovoltaic device was prepared and tested and evaluated in the same manner as in Example 16 except that a 0.005 mol / l hydrochloric acid aqueous solution was used as the aqueous solution 2 to be etched. Was found to be as excellent as the photovoltaic element of Example 16.
[0123]
(Example 22)
A photovoltaic device was prepared and tested and evaluated in the same manner as in Example 16 except that a 0.1 mol / l sodium acetate aqueous solution was used as the aqueous solution 2 to be etched. The device was found to be as good as the photovoltaic device of Example 17.
[0124]
(Example 23)
An experiment was conducted in which the saccharose content in the aqueous solution for forming the first zinc oxide layer was changed. When a photovoltaic device similar to that of Example 17 was prepared by changing the saccharose content in the aqueous solution from 0 to 800 g / l in Example 17, the saccharose content was 1 g / l or more, 300 as shown in FIG. Photoelectric conversion efficiency was maximized when g / l or less.
[0125]
When the cross section of the zinc oxide layer was observed with an SEM, there were many abnormal plate-like growths when the saccharose was 1 g / l or less. The leakage current was increased and the photoelectric conversion efficiency was lowered. Conversely, when the saccharose was 300 g / l or more, the shape obtained by etching the zinc oxide layer was too flat to perform light confinement or light diffusion, and the photoelectric conversion efficiency was lowered.
[0126]
The same was found with respect to the sucrose content of the aqueous solution for forming the second zinc oxide layer.
[0127]
(Example 24)
In Example 18, a photovoltaic device in which the intermediate layer was made of tin oxide was produced. A photovoltaic device was prepared, measured and evaluated in the same manner as in Example 18 except that an intermediate layer made of tin oxide having a thickness of 0.1 μm was formed by sputtering. As a result, the same excellent characteristics as in Example 18 were obtained. Had.
[0128]
(Example 25)
A photovoltaic device having a back reflective layer made of copper was produced. A photovoltaic device similar to that of Example 17 was prepared except that the back surface reflective layer made of copper was prepared by an electrodeposition method. As a result, it was found that the photovoltaic device was as excellent as the photovoltaic device of Example 17.
[0129]
(Example 26)
When the first transparent conductive layer and the second transparent conductive layer are formed by the electrodeposition method, dextrin is added to the first aqueous solution and the second aqueous solution at a rate of 0.1 (g / l), and the photovoltaic A power device was created. Measurement and evaluation were performed in the same manner as in Example 16 except that the additive was dextrin. As a result, it was found that the solar cell of Example 26 was superior to the solar cell of Example 16.
[0130]
(Example 27)
An experiment was conducted in which the dextrin content in the aqueous solution was changed. In Example 26, the dextrin content in the aqueous solution was changed from 0 to 100 g / l to produce a photovoltaic device similar to that in Example 26. As shown in FIG. 11, the dextrin content was 0.001 g / l or more. When it is 10 g / l or less, the photoelectric conversion efficiency becomes maximum. The same was found regarding the dextrin content of the aqueous solution for forming the second zinc oxide layer.
[0131]
[Table 1]

[0132]
[Table 2]

[0133]
[Table 3]

[0134]
[Table 4]

[0135]
[Table 5]

[0136]
[Table 6]

[0137]
[Table 7]

[0138]
[Table 8]

[0139]
[Table 9]

[0140]
[Table 10]

[0141]
[Table 11]

[0142]
【The invention's effect】
According to the photovoltaic device manufacturing method of the present invention, a zinc oxide layer having unevenness with excellent light confinement effect can be formed, so that the photoelectric conversion efficiency, short-circuit photocurrent, leakage current, etc. of the photovoltaic device The photoconductive property can be improved. Moreover, durability in outdoor exposure test, mechanical strength, HH (high temperature and high humidity environment) test, and long-time light irradiation can be improved. Furthermore, the cost of the photovoltaic element can be greatly reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a photovoltaic element of the present invention.
FIG. 2 is a diagram showing an apparatus for producing zinc oxide according to the present invention.
FIG. 3 is a sectional view of the zinc oxide layer of the present invention.
FIG. 4 is a diagram showing an apparatus for continuously producing zinc oxide according to the present invention.
FIG. 5 is a graph showing the relationship between the sucrose content in an aqueous solution and the photoelectric conversion efficiency.
FIG. 6 is a graph showing the relationship between the thickness of a zinc oxide layer and photoelectric conversion efficiency.
FIG. 7 is a graph showing the relationship between the layer thickness of the lower layer of the zinc oxide layer and the photoelectric conversion efficiency.
FIG. 8 is a graph showing the relationship between the layer thickness of the upper layer of the zinc oxide layer and the photoelectric conversion efficiency.
FIG. 9 is a graph showing the relationship between dextrin content in an aqueous solution and photoelectric conversion efficiency.
FIG. 10 is a graph showing the relationship between the sucrose content in an aqueous solution and the photoelectric conversion efficiency.
FIG. 11 is a graph showing the relationship between dextrin content in aqueous solution and photoelectric conversion efficiency.
[Explanation of symbols]
101 conductive substrate
102 Back reflective layer
103 (a) Upper layer
104 (a) Lower layer
103 (b) First zinc oxide layer
104 (b) Second zinc oxide layer
105 Semiconductor layer
110 Zinc oxide layer
201 conductive substrate
202 Counter electrode
203 Aqueous solution
205 power supply
208 heater
320 sharp hole
321 Loose hole
323 Surface of zinc oxide layer before etching
324 Surface of zinc oxide layer after etching
325 Surface after deposition of second zinc oxide layer
327 Sharp hole left after etching
401 substrate
402 Washing tank 1
403 Ultrasonic diaphragm
404 Circulator
405 heater
406 Electrodeposition tank 1
407 Circulator
408 Zinc electrode
409 Heater
410 constant current power supply
411 Washing tank 2
412 Circulator
413 Ultrasonic vibration plate
414 heater
415 Etching tank
416 Circulator
417 Heater
418 Washing tank 3
419 Circulator
420 Ultrasonic vibration plate
421 heater
422 Electrodeposition tank 2
423 Heater
424 Circulator
425 Zinc electrode
426 constant current power supply
427 Washing tank 4
428 Ultrasonic vibration plate
429 heater
430 Circulator
431 Drying room
432 Transport roll
433 Delivery roll
434 Winding roll

Claims (48)

By energizing between a conductive substrate immersed in a first aqueous solution containing at least nitrate ions and zinc ions and an electrode immersed in the solution, the first zinc oxide layer is electrically conductive. And a step of etching the first zinc oxide layer and a step of forming a semiconductor layer, wherein the first aqueous solution contains a carbohydrate. Device manufacturing method. Between the step of etching and the step of forming a semiconductor layer, the conductive substrate on which the first zinc oxide layer is formed is immersed in a second aqueous solution containing at least nitrate ions and zinc ions, A step of forming a second zinc oxide layer on the first zinc oxide layer by energizing the electrode immersed in the solution, wherein the first or second aqueous solution is a carbohydrate The method for producing a photovoltaic element according to claim 1, comprising: It said carbohydrate is monosaccharide, disaccharide, or method of producing a photovoltaic element according to claim 1 or 2, characterized in that a polysaccharide. The method for producing a photovoltaic device according to claim 1 or 2, wherein the first aqueous solution contains 1 to 300 g / l of saccharose. The method for producing a photovoltaic device according to claim 1 or 2, wherein the first aqueous solution contains 0.001 to 10 g / l of dextrin. 3. The method of manufacturing a photovoltaic element according to claim 1, wherein the first zinc oxide layer is composed of two layers, an upper layer and a lower layer. The method for manufacturing a photovoltaic device according to claim 6, wherein the formation temperature of the upper layer is higher than the formation temperature of the lower layer. The photovoltaic element manufacturing method according to claim 7, wherein the formation temperature of the upper layer is 80 ° C. or more. The method for manufacturing a photovoltaic device according to claim 6, wherein a current density for forming the upper layer is lower than a current density for forming the lower layer. The photovoltaic element manufacturing method according to claim 6, wherein the concentration of nitrate ions and zinc ions when forming the upper layer is lower than each concentration when forming the lower layer. The photovoltaic device manufacturing method according to claim 1, wherein the etching is performed with acetic acid or an aqueous solution thereof. The method includes a step of washing before the step of forming the first zinc oxide layer, between the step of forming the first zinc oxide layer and the step of etching, or after the step of etching. The manufacturing method of the photovoltaic element of Claim 1. 2. The photovoltaic device according to claim 1, wherein the first zinc oxide layer has a hole on a surface thereof, and the diameter of the hole before the etching step is 0.05 to 0.3 μm. 3. Production method. 2. The method of manufacturing a photovoltaic element according to claim 1, wherein the first zinc oxide layer has a hole on a surface before the etching step and has no hole after the etching step. The method for producing a photovoltaic device according to claim 1, wherein the zinc oxide layer has holes on the surface, and the density of the holes is 100 to 1000 per 100 µm ² . 2. The method of manufacturing a photovoltaic element according to claim 1, wherein a second zinc oxide layer is formed on the first zinc oxide layer by sputtering. 2. The method for manufacturing a photovoltaic element according to claim 1, wherein the conductive substrate is a kind selected from a stainless steel plate, a steel plate, a copper plate, a brass plate, and an aluminum plate. The method for manufacturing a photovoltaic element according to claim 1, wherein a metal layer is formed on the conductive substrate. 2. The method of manufacturing a photovoltaic element according to claim 1, wherein the conductive substrate is formed by forming a metal layer on at least one surface selected from glass, ceramic, or resin. The method for manufacturing a photovoltaic device according to claim 18, wherein the metal layer is one type selected from Au, Ag, Cu, CuMg, or Al. The method for manufacturing a photovoltaic element according to claim 18, wherein the metal layer is Al, and includes a step of forming an intermediate layer before forming the zinc oxide layer. The method for manufacturing a photovoltaic element according to claim 21, wherein the intermediate layer is one kind selected from zinc oxide, tin oxide, indium oxide, or ITO. 2. The method of manufacturing a photovoltaic element according to claim 1, wherein the thickness of the first zinc oxide layer is 0.7 to 3 [mu] m. The method of manufacturing a photovoltaic element according to claim 6, wherein a thickness of a lower layer of the first zinc oxide layer is 0.5 μm or more. The method of manufacturing a photovoltaic element according to claim 6, wherein a layer thickness of an upper layer of the first zinc oxide layer is 0.2 μm or more. The thickness of the first zinc oxide layer is 0.5 μm or more, the layer thickness of the second zinc oxide layer is 0.05 μm or more, and the two layers together are 0.7 μm or more and 3 μm or less. The manufacturing method of the photovoltaic element of Claim 2. 27. The method for manufacturing a photovoltaic device according to claim 26, wherein the carbohydrate is a monosaccharide, a disaccharide, or a polysaccharide. The method for manufacturing a photovoltaic device according to claim 2, wherein the first or second aqueous solution contains 1 to 300 g / l of saccharose. The method for producing a photovoltaic device according to claim 2, wherein the first or second aqueous solution contains 0.001 to 10 g / l of dextrin. 3. The method of manufacturing a photovoltaic element according to claim 2, wherein the first zinc oxide layer is composed of two layers, an upper layer and a lower layer. The method for manufacturing a photovoltaic device according to claim 30, wherein the formation temperature of the upper layer is higher than the formation temperature of the lower layer. 32. The method of manufacturing a photovoltaic device according to claim 31, wherein the formation temperature of the upper layer is 80 [deg.] C. or higher. The method of manufacturing a photovoltaic element according to claim 30, wherein a current density for forming the upper layer is lower than a current density for forming the lower layer. 31. The method of manufacturing a photovoltaic device according to claim 30, wherein concentrations of nitrate ions and zinc ions when forming the upper layer are lower than respective concentrations when forming the lower layer. The method of manufacturing a photovoltaic device according to claim 2, wherein the etching is performed with acetic acid or an aqueous solution thereof. The method includes a step of washing before the step of forming the second zinc oxide layer, between the step of forming the second zinc oxide layer and the step of etching, or after the step of etching. The manufacturing method of the photovoltaic element of Claim 2. 3. The photovoltaic device according to claim 2, wherein the second zinc oxide layer has a hole on a surface thereof, and the diameter of the hole before the etching step is 0.05 to 0.3 [mu] m. Production method. 3. The method of manufacturing a photovoltaic element according to claim 2, wherein the second zinc oxide layer has a hole in the surface before the etching step and does not have a hole after the etching step. The method for producing a photovoltaic device according to claim 2, wherein the second zinc oxide layer has holes on the surface, and the density of the holes is 100 to 1000 per 100 µm ² . 3. The method of manufacturing a photovoltaic element according to claim 2, wherein the conductive substrate is a kind selected from a stainless steel plate, a steel plate, a copper plate, a brass plate, and an aluminum plate. 3. The method of manufacturing a photovoltaic element according to claim 2, wherein a metal layer is formed on the conductive substrate. 3. The method of manufacturing a photovoltaic element according to claim 2, wherein the conductive substrate is formed by forming a metal layer on at least one surface selected from glass, ceramic, or resin. 43. The method of manufacturing a photovoltaic element according to claim 41, wherein the metal layer is one kind selected from Au, Ag, Cu, CuMg, or Al. 43. The method of manufacturing a photovoltaic element according to claim 41, wherein the metal layer is Al and includes a step of forming an intermediate layer before forming the zinc oxide layer. 45. The method of manufacturing a photovoltaic element according to claim 44, wherein the intermediate layer is one kind selected from zinc oxide, tin oxide, indium oxide, or ITO. 3. The method of manufacturing a photovoltaic element according to claim 2, wherein the sum of the thickness of the first zinc oxide layer and the thickness of the second zinc oxide layer is 0.7 to 3 [mu] m. The method of manufacturing a photovoltaic element according to claim 30, wherein a thickness of a lower layer of the first zinc oxide layer is 0.5 µm or more. 31. The method of manufacturing a photovoltaic element according to claim 30, wherein a layer thickness of an upper layer of the first zinc oxide layer is 0.2 [mu] m or more.

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