JP2006270024A - Covering stainless foil and silicon film solar battery - Google Patents
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本発明は、シリカ系無機ポリマー膜で被覆したステンレス箔及びシリコン薄膜太陽電池に関するものである。 The present invention relates to a stainless steel foil and a silicon thin film solar cell coated with a silica-based inorganic polymer film.
太陽光発電は、新しいエネルギー源の1つとして注目されている。太陽電池としては、単結晶Si又は多結晶Siのバルク型太陽電池が主流であるが、軽量化・大面積化・量産による低価格化等、薄膜太陽電池の方が有利と考えられる点も多い。 Solar power generation is attracting attention as one of the new energy sources. As solar cells, bulk solar cells of single crystal Si or polycrystal Si are the mainstream, but there are many points where thin film solar cells are considered to be more advantageous, such as weight reduction, large area, and cost reduction by mass production. .
薄膜太陽電池の基板としては、ガラスが用いられているが、軽量化・フレキシビリティの観点から、樹脂基板も検討されている。しかしながら、樹脂は耐熱性が低いため、薄膜太陽電池の製造プロセス温度が制限される。このため、表面に絶縁膜をつけたステンレス箔基板が提案されている(特許文献1)。太陽電池基板としては、複数のセルを配列して一定の性能が得られるように、少なくともMΩ・cm2オーダーの絶縁性が求められるので、ステンレス箔上の膜にもこのレベルの絶縁性が求められる。金属箔の上に、絶縁性の高いポリイミド塗料等の有機樹脂塗料を塗布したものを使用する例がある(特許文献2)が、有機樹脂は、太陽電池セル形成時の200〜350℃の熱処理で劣化するものが多い。 Glass is used as the substrate of the thin film solar cell, but a resin substrate is also being studied from the viewpoint of weight reduction and flexibility. However, since the resin has low heat resistance, the manufacturing process temperature of the thin film solar cell is limited. For this reason, a stainless steel foil substrate with an insulating film on the surface has been proposed (Patent Document 1). As a solar cell substrate, insulation of at least MΩ · cm 2 order is required so that a certain performance can be obtained by arranging a plurality of cells. Therefore, this level of insulation is also required for the film on the stainless steel foil. It is done. There is an example using a metal foil coated with an organic resin paint such as a highly insulating polyimide paint (Patent Document 2), but the organic resin is a heat treatment at 200 to 350 ° C. during the formation of solar cells. There are many things that deteriorate.
薄膜太陽電池の中でも、高い変換効率が期待される結晶系Si薄膜太陽電池が、最近、注目されている。従来、この材料は、可視域での吸収係数が小さいので、薄膜材料には適さないと考えられていたが、結晶系Siにおいても、長い光路長を得られるよう、結晶系Si層の裏面及び表面に光を反射させて、中に閉じ込めることにより、高い変換効率を実現することが判ってきた。例えば、ガラス基板の上に、凹凸テクスチャ構造を有する裏面反射層としてSnO2を設け、その上にn型Si層、活性層となるi層、p型Si層、ITO膜を順次積層し、セルを作製している。裏面反射層は、電極も兼ねた構造になっている(非特許文献1)。また、アモルファスSiにおいても、変換効率を上げるために、アモルファスSi層の表面、裏面のそれぞれに凹凸テクスチャ構造を持たせて、光路長を稼いだ場合についてシミュレーションした結果、凹凸テクスチャ構造の有効性が示されている(非特許文献2)。 Among thin film solar cells, crystalline Si thin film solar cells that are expected to have high conversion efficiency have recently attracted attention. Conventionally, this material has been considered to be unsuitable for thin film materials because of its small absorption coefficient in the visible region. However, in order to obtain a long optical path length even in crystalline Si, the backside of the crystalline Si layer and It has been found that high conversion efficiency is achieved by reflecting light on the surface and confining it inside. For example, SnO 2 is provided on a glass substrate as a back reflective layer having an uneven texture structure, and an n-type Si layer, an i layer serving as an active layer, a p-type Si layer, and an ITO film are sequentially stacked on the glass substrate. Is making. The back reflective layer has a structure that also serves as an electrode (Non-Patent Document 1). In addition, in order to increase the conversion efficiency in amorphous Si, as a result of simulating the case where the surface of the amorphous Si layer has an uneven texture structure on each of the front and back surfaces to increase the optical path length, the effectiveness of the uneven texture structure is confirmed. (Non-Patent Document 2).
現在のところ、凹凸テクスチャ構造は、ガラス基板上に透明電極としてSnO2又はZnOをCVD又はスパッタリングで作製後、酸によるウエットエッチングで得ているものが主流である。しかしながら、軽量化・フレキシビリティ・耐熱性等の観点から金属箔基板の採用を考えた場合、SnO2やZnOの酸によるウエットエッチングプロセスでは、金属自体の腐食が問題になるため、凹凸テクスチャ構造を作ることができなかった。裏面電極として、Al等の金属を凹凸テクスチャ構造を有する形に成膜することも考えられるが、現実には、光閉じ込め効果が発現するようなサブミクロンレベルの凹凸を有する電極膜をAl等で成膜する技術は確立していない。 At present, the uneven texture structure is mainly obtained by producing SnO 2 or ZnO as a transparent electrode on a glass substrate by CVD or sputtering and then wet etching with acid. However, when considering the use of metal foil substrates from the viewpoint of weight reduction, flexibility, heat resistance, etc., the wet etching process with SnO 2 or ZnO acid causes a problem of corrosion of the metal itself, so that an uneven texture structure is used. I couldn't make it. Although it is conceivable to form a metal such as Al in a shape having a concavo-convex texture structure as the back electrode, in reality, an electrode film having concavo-convex of submicron level that exhibits a light confinement effect is formed of Al or the like. The technology for film formation has not been established.
本発明は、1MΩ・cm2オーダー以上の絶縁性、熱安定性、及び、薄膜太陽電池として凹凸テクスチャ構造を有する裏面反射層が作製可能な、シリカ系無機ポリマー膜で被覆されたステンレス箔及びシリコン薄膜太陽電池を提供するものである。 The present invention relates to a stainless steel foil and silicon coated with a silica-based inorganic polymer film, capable of producing a back-reflection layer having an uneven texture structure as a thin film solar cell, with an insulation property of 1 MΩ · cm 2 order or more, thermal stability, and A thin film solar cell is provided.
前記課題は、上記目的を達成するために以下のような手段を用いる。
(1) ステンレス箔表面に、Si-R結合(Rは有機基又は水素)を含むシロキサン結合を主体とする無機ポリマーから成る下地膜と、その上に、シロキサン結合を主体とする無機ポリマー中に、粒径50nm以上5000nm以下の球状フィラーを膜中に15質量%以上90質量%以下含む凹凸膜を有することを特徴とする被覆ステンレス箔。
(2) ステンレス箔表面に、Si-R結合(Rは有機基又は水素)を含むシロキサン結合を主体とする無機ポリマーから成る下地膜と、その上に、シロキサン結合を主体とする無機ポリマー中に、粒径50nm以上1000nm以下の球状フィラーを膜中に15質量%以上50質量%以下含む凹凸膜を有することを特徴とする被覆ステンレス箔。
(3) 前記球状フィラーによるオーバーハング領域が全基板面積の3%以下である凹凸膜を有することを特徴とする(1)又は(2)に記載の被覆ステンレス箔。
(4) 前記下地膜の膜厚が4μm以上200μm以下である(1)又は(2)に記載の被覆ステンレス箔。
(5) 前記下地膜の膜厚が4μm以上20μm以下である(1)又は(2)に記載の被覆ステンレス箔。
(6) 前記凹凸膜の膜厚が0.2μm以上3μm以下である(1)、(2)又は(3)に記載の被覆ステンレス箔。
(7) 前記球状フィラーによる凹凸の凸部高さが30nm以上3000nm以下のものが全凸部の70%以上である(1)、(2)、(3)又は(6)に記載の被覆ステンレス箔。
(8) 前記球状フィラーによる凹凸の凸部高さが30nm以上1000nm以下のものが全凸部の70%以上である(1)、(2)、(3)又は(6)に記載の被覆ステンレス箔。
(9) 前記球状フィラーによる凹凸の凸部径が30nm以上3000nm以下のものが全凸部の70%以上である(1)、(2)、(3)又は(6)に記載の被覆ステンレス箔。
(10) 前記球状フィラーによる凹凸の凸部径が30nm以上1000nm以下のものが全凸部の70%以上である(1)、(2)、(3)又は(6)に記載の被覆ステンレス箔。
(11) 前記球状フィラーによる凹凸の凸部面積が全基板面積の10%以上90％以下である (1)、(2)、(3)又は(6)に記載の被覆ステンレス箔。
(12) 前記下地膜を構成する無機ポリマーのシロキサン骨格を修飾する有機基がメチル基又はフェニル基の一方又は両方であり、かつ、前記有機基のSiに対するモル比が1以上2.2以下である(1)、(2)、(4)又は(5)に記載の被覆ステンレス箔。
(13) 前記球状フィラーがコロイダルシリカである(1)〜(3)、(7)〜(11)のいずれかに記載の被覆ステンレス箔。
(14) 前記凹凸膜のマトリックス部分が、全Siに対してエポキシ基を0.2以上0.7以下含むシリカ系無機ポリマーである(1)、(2)、(3)又は(6)に記載の被覆ステンレス箔。
(15) (1)〜(14)のいずれかに記載の被覆ステンレス箔を基板に用いてなることを特徴とするシリコン薄膜太陽電池。
The above object uses the following means in order to achieve the above object.
(1) A base film made of an inorganic polymer mainly composed of siloxane bonds containing Si-R bonds (R is an organic group or hydrogen) on the surface of the stainless steel foil, and an inorganic polymer mainly composed of siloxane bonds thereon. A coated stainless steel foil characterized by having a concavo-convex film containing a spherical filler having a particle size of 50 nm or more and 5000 nm or less in a film of 15% by mass or more and 90% by mass or less.
(2) On the surface of the stainless steel foil, a base film made of an inorganic polymer mainly composed of siloxane bonds containing Si-R bonds (R is an organic group or hydrogen), and an inorganic polymer mainly composed of siloxane bonds A coated stainless steel foil comprising a concavo-convex film containing a spherical filler having a particle size of 50 nm or more and 1000 nm or less in a film of 15 mass% or more and 50 mass% or less.
(3) The coated stainless steel foil according to (1) or (2), wherein the overhang region formed by the spherical filler has a concavo-convex film having 3% or less of the total substrate area.
(4) The coated stainless steel foil according to (1) or (2), wherein a film thickness of the base film is 4 μm or more and 200 μm or less.
(5) The coated stainless steel foil according to (1) or (2), wherein the film thickness of the base film is 4 μm or more and 20 μm or less.
(6) The coated stainless steel foil according to (1), (2) or (3), wherein the uneven film has a thickness of 0.2 μm or more and 3 μm or less.
(7) The coated stainless steel according to (1), (2), (3) or (6), wherein the height of the convex portions of the concave and convex portions by the spherical filler is 70% or more of the total convex portions. Foil.
(8) The coated stainless steel according to (1), (2), (3), or (6), wherein the height of the convex portion of the concave and convex portions by the spherical filler is not less than 70% of the total convex portion. Foil.
(9) The coated stainless steel foil according to (1), (2), (3) or (6), wherein the convex portion diameter of the concave and convex portions by the spherical filler is 70% or more of the total convex portion. .
(10) The coated stainless steel foil according to (1), (2), (3) or (6), wherein the convex portion diameter of the concave and convex portions by the spherical filler is 70% or more of the total convex portion .
(11) The coated stainless steel foil according to (1), (2), (3) or (6), wherein the convex and concave portions of the spherical filler have an area of 10% to 90% of the total substrate area.
(12) The organic group modifying the siloxane skeleton of the inorganic polymer constituting the base film is one or both of a methyl group and a phenyl group, and the molar ratio of the organic group to Si is 1 or more and 2.2 or less ( The coated stainless steel foil according to 1), (2), (4) or (5).
(13) The coated stainless steel foil according to any one of (1) to (3) and (7) to (11), wherein the spherical filler is colloidal silica.
(14) The coated stainless steel according to (1), (2), (3) or (6), wherein the matrix portion of the concavo-convex film is a silica-based inorganic polymer containing an epoxy group of 0.2 to 0.7 with respect to all Si Foil.
(15) A silicon thin film solar cell comprising the coated stainless steel foil according to any one of (1) to (14) as a substrate.
本発明によれば、表面に凹凸構造を有するシロキサン結合を主体とする無機ポリマー膜で被覆されたステンレス箔が得られ、太陽電池をはじめ各種電気・電子部品用に軽量で可とう性を備えた絶縁基板を提供することができる。本発明のステンレス箔は、特に、シリコン薄膜太陽電池基板として用いた場合、凹凸構造を有する裏面反射層が得られるので光路長を稼ぐことができる。したがって、本発明のステンレス箔により、シリコン薄膜太陽電池の電流密度が上がり、太陽電池としての変換効率を向上させることができる。 According to the present invention, a stainless steel foil coated with an inorganic polymer film mainly composed of a siloxane bond having a concavo-convex structure on its surface is obtained, and it is lightweight and flexible for various electric and electronic parts including solar cells. An insulating substrate can be provided. Especially when the stainless steel foil of the present invention is used as a silicon thin film solar cell substrate, a back surface reflecting layer having a concavo-convex structure can be obtained, so that the optical path length can be increased. Therefore, with the stainless steel foil of the present invention, the current density of the silicon thin film solar cell is increased, and the conversion efficiency as the solar cell can be improved.
無機ポリマーは、M(金属又は半金属)-O(酸素)-Mの無機結合で骨格が主骨格が構成されているポリマーである。特に、MがSiの場合は、シロキサン結合と呼ばれる。Siの4つの結合手の内の全てがSi-O-Si結合でつながっている場合は、SiO2ガラスになる。 SiO2ガラスは硬く、クラックが入り易い。一般に、ステンレス箔表面の表面粗さは、Ra=0.03〜0.6μm、Rmax=0.35〜3.0μmであるため、数μm以上の膜厚がなければ、絶縁性を維持することができない。スパッタ法、CVD法、ゾルゲル法等いずれの成膜方法においても、クラックなく1μm近い厚さのSiO2膜を成膜することは困難である。 The inorganic polymer is a polymer whose main skeleton is composed of inorganic bonds of M (metal or metalloid) -O (oxygen) -M. In particular, when M is Si, it is called a siloxane bond. When all of the four bonds of Si are connected by Si-O-Si bonds, it becomes SiO 2 glass. SiO 2 glass is hard and easily cracked. In general, the surface roughness of the stainless steel foil surface is Ra = 0.03 to 0.6 μm and R max = 0.35 to 3.0 μm. Therefore, the insulation cannot be maintained without a film thickness of several μm or more. In any film formation method such as sputtering, CVD, or sol-gel, it is difficult to form a SiO 2 film having a thickness of nearly 1 μm without cracks.
SiO2ガラスの硬さを緩和するために、Si-R(Rは有機基又は水素)結合を導入したシロキサン結合を主体とする無機ポリマー膜にすると、膜に柔軟性が付与されるので、厚膜にしてもクラックが入り難くなり、1MΩ・cm2以上の絶縁抵抗値を得ることが可能になる。シロキサン結合を主体とする無機ポリマー膜とは、無機ポリマー膜を形成しているM-O-Mの無機結合の内、Si-O-Si結合が90%以上を占めているものを指す。Si-O-Si結合以外の無機結合としては、例えば、Si-O-Ti、Ti-O-Ti、Al-O-Ti等の結合が挙げられる。Si-R結合は、シロキサン骨格を修飾して無機ポリマー膜に柔軟性を付与する効果がある。Si-R結合を含みシロキサン結合を主体とする無機ポリマー膜は、高い絶縁抵抗値が得られるが、一般に平滑な面となり凹凸表面は得られないので、本発明においては、この無機ポリマー膜を下地膜として用いる。Rとしては、水素の他に、メチル基、エチル基、プロピル基、フェニル基、グリシドキシプロピル基、アミノ基、トリフルオロプロピル基等が挙げられる。R(有機基又は水素)とSiのモル比は、1以上2.2以下であることが望ましい。 In order to reduce the hardness of the SiO 2 glass, an inorganic polymer film mainly composed of siloxane bonds with Si-R (R is an organic group or hydrogen) bond is used to give flexibility to the film. Even if it is a film, cracks are difficult to occur, and an insulation resistance value of 1 MΩ · cm 2 or more can be obtained. The inorganic polymer film mainly composed of siloxane bonds refers to those in which 90% or more of Si-O-Si bonds occupy the inorganic bonds of the MOM forming the inorganic polymer film. Examples of the inorganic bond other than the Si—O—Si bond include bonds such as Si—O—Ti, Ti—O—Ti, and Al—O—Ti. The Si-R bond has an effect of modifying the siloxane skeleton and imparting flexibility to the inorganic polymer film. An inorganic polymer film containing a Si-R bond and mainly having a siloxane bond can provide a high insulation resistance value, but generally has a smooth surface and an uneven surface cannot be obtained. Used as a base film. Examples of R include, in addition to hydrogen, a methyl group, an ethyl group, a propyl group, a phenyl group, a glycidoxypropyl group, an amino group, and a trifluoropropyl group. The molar ratio of R (organic group or hydrogen) and Si is preferably 1 or more and 2.2 or less.
一方、薄膜太陽電池基板としては、表面に光を乱反射させるような凹凸形状を有することが望まれる。太陽電池セル形成時の200〜350℃の熱処理条件に耐えられ、かつ、凹凸形状を付与する方法として、無機ポリマー中に球状フィラーを分散させることが考えられる。 On the other hand, it is desired that the thin film solar cell substrate has a concavo-convex shape that diffusely reflects light on the surface. It is conceivable to disperse spherical fillers in the inorganic polymer as a method that can withstand the heat treatment conditions of 200 to 350 ° C. at the time of forming the solar battery cell and give the uneven shape.
凹凸形状を付与する際に用いる無機ポリマー膜は、シロキサン結合を主体とする無機ポリマー膜である。シロキサン結合を主体とする無機ポリマー膜とは、下地膜として用いる無機ポリマー膜同様、無機ポリマー膜を形成しているM-O-Mの無機結合の内、Si-O-Si結合が90%以上を占めているものを指す。凹凸形状を付与する際に用いる無機ポリマー膜は、Si-R結合を含んでいても、含んでいなくてもよい。凹凸を付与するのに適した球状フィラーの粒径は、50nm以上5000nm以下である。また50nm以上1000nm以下でもよい。粒径が50nmより小さいときは、凝集により二次粒子を生成し易く、一次粒子による凹凸に加えて、数μmレベルの二次粒子による凹凸が形成され易くなり、適切な光閉じ込め効果が得られない。粒径が5000nmより大きい場合は、凹凸が大きくなり過ぎるため、適切な光閉じ込め効果が得られない。粒径が1000nm以下であればサブミクロンレベルの凹凸を付与できる。凹凸を付与するのに適した球状フィラーの粒径のより好ましい範囲は、300nm以上3000nm以下である。無機ポリマー中の球状フィラーの含有率は、15質量%以上90質量%以下である。ここで、無機ポリマー中の球状フィラーの含有率は、球状フィラーの質量/(球状フィラーの質量+無機ポリマーの質量)で求められるものである。この含有率が15質量%より少ないときは、十分な凹凸が得られない。90質量%を超える場合は、粒子が凝集し易くなる。球状フィラーの含有率のより好ましい範囲は、30質量%以上75質量%以下である。なお、サブミクロンレベルの凹凸を形成する場合は50質量％以下が好ましい。 The inorganic polymer film used for imparting the uneven shape is an inorganic polymer film mainly composed of siloxane bonds. The inorganic polymer film mainly composed of siloxane bonds is 90% or more of the inorganic bonds of the MOM that forms the inorganic polymer film, like the inorganic polymer film used as the base film. Refers to things. The inorganic polymer film used for imparting the uneven shape may or may not contain Si-R bonds. The particle size of the spherical filler suitable for imparting unevenness is 50 nm or more and 5000 nm or less. Moreover, 50 nm or more and 1000 nm or less may be sufficient. When the particle size is smaller than 50 nm, secondary particles are likely to be generated by agglomeration, and in addition to irregularities due to primary particles, irregularities due to secondary particles of several μm level are likely to be formed, and an appropriate light confinement effect can be obtained. Absent. When the particle diameter is larger than 5000 nm, the unevenness becomes too large, so that an appropriate light confinement effect cannot be obtained. If the particle size is 1000 nm or less, irregularities on the submicron level can be provided. A more preferable range of the particle size of the spherical filler suitable for imparting unevenness is 300 nm or more and 3000 nm or less. The content of the spherical filler in the inorganic polymer is 15% by mass or more and 90% by mass or less. Here, the content of the spherical filler in the inorganic polymer is determined by the mass of the spherical filler / (the mass of the spherical filler + the mass of the inorganic polymer). When the content is less than 15% by mass, sufficient unevenness cannot be obtained. When it exceeds 90% by mass, the particles tend to aggregate. A more preferable range of the content of the spherical filler is 30% by mass or more and 75% by mass or less. In addition, when forming a submicron level unevenness | corrugation, 50 mass% or less is preferable.
球状フィラーを分散させた無機ポリマー膜は、表面に凹凸構造を付与するのには適しているが、フィラーとマトリックスになる無機ポリマーの間に微細な空隙を含む場合が多く、この膜単独では、1MΩ・cm2以上の高い絶縁抵抗の膜を形成することは困難である。 An inorganic polymer film in which spherical fillers are dispersed is suitable for imparting a concavo-convex structure on the surface, but often contains fine voids between the filler and the inorganic polymer that becomes the matrix. It is difficult to form a film having a high insulation resistance of 1 MΩ · cm 2 or more.
本発明では、1MΩ・cm2以上の絶縁抵抗と、表面凹凸形状を両立させるため、ステンレス箔表面に、Si-R結合(Rは有機基又は水素)を含むシロキサン結合を主体とする無機ポリマーからなる下地膜と、その上に、シロキサン結合を主体とする無機ポリマー中に、粒径50nm以上5000nm以下の球状フィラーを膜中に15質量%以上90質量%以下含む凹凸膜を有することを特徴とする下地膜と凹凸膜の二層で、ステンレス箔を被覆することを見出した。 In the present invention, in order to achieve both an insulation resistance of 1 MΩ · cm 2 or more and an uneven surface shape, the surface of the stainless steel foil is made of an inorganic polymer mainly composed of siloxane bonds containing Si—R bonds (R is an organic group or hydrogen). And an uneven film containing a spherical filler having a particle size of 50 nm or more and 5000 nm or less in a film of 15% by mass or more and 90% by mass or less in an inorganic polymer mainly composed of a siloxane bond. It has been found that a stainless steel foil is coated with two layers of a base film and an uneven film.
本発明による凹凸膜の凸部は、球状フィラーの体積の過半が平滑面の外側に出ている場合でも、図1に示すように、凹凸膜のマトリックスがテールを引いて、オーバーハングしていない形状になることが望ましい。図2に示すような球状フィラーによるオーバーハングがある場合、平面図に示したようなオーバーハング領域は、全基板面積の3%以下であることが望ましい。オーバーハング領域では、薄膜太陽電池の各層が不連続に形成されることになる。したがって、オーバーハング領域が、全基板面積の3%を越えると、太陽電池の特性が著しく劣化する可能性がある。オーバーハング領域は、全基板面積に対して1%以下であることが、特に好ましい。 As shown in FIG. 1, the convex and concave portions of the concavo-convex film according to the present invention do not overhang as the concavo-convex film matrix has a tail as shown in FIG. 1, even when a majority of the volume of the spherical filler is outside the smooth surface. It is desirable to have a shape. When there is an overhang due to the spherical filler as shown in FIG. 2, the overhang region as shown in the plan view is desirably 3% or less of the total substrate area. In the overhang region, each layer of the thin film solar cell is formed discontinuously. Therefore, if the overhang region exceeds 3% of the total substrate area, the characteristics of the solar cell may be significantly deteriorated. The overhang region is particularly preferably 1% or less with respect to the total substrate area.
本発明の下地膜の厚さは、4μm以上200μm以下であることが望ましい。下地膜の厚さが4μmより薄い場合は、十分な絶縁性が得られ難く、200μmを超える場合は、膜の焼き付け時にクラックが入り易くなる。下地膜の厚さのより好ましい範囲は、4μm以上20μm以下、さらに好ましくは4μm以上13μm以下である。 The thickness of the base film of the present invention is preferably 4 μm or more and 200 μm or less. When the thickness of the underlying film is less than 4 μm, it is difficult to obtain sufficient insulation, and when it exceeds 200 μm, cracks are likely to occur when the film is baked. A more preferable range of the thickness of the base film is 4 μm or more and 20 μm or less, and more preferably 4 μm or more and 13 μm or less.
凹凸膜の膜厚は、0.2μm以上3μm以下であることが望ましい。本発明の凹凸膜は、図3に示すように、平滑な面の上に球状フィラーの各粒子に対応して凸部が形成された表面構造を有する。凹凸膜の膜厚とは、平滑面の膜厚のことである。凹凸膜の膜厚が0.2μmより薄い場合は、球状フィラーの保持が不十分となり、球状フィラーが膜から脱離し易くなる。3μmより厚い場合は、凹凸膜にクラックが発生し易くなる。凹凸膜の厚さのより好ましい範囲は、0.3μm以上1.2μm以下である。 The film thickness of the uneven film is preferably 0.2 μm or more and 3 μm or less. As shown in FIG. 3, the concavo-convex film of the present invention has a surface structure in which convex portions are formed on a smooth surface corresponding to each particle of the spherical filler. The film thickness of the concavo-convex film is the film thickness of the smooth surface. When the film thickness of the concavo-convex film is thinner than 0.2 μm, the spherical filler is not sufficiently retained, and the spherical filler is easily detached from the film. When it is thicker than 3 μm, cracks are likely to occur in the uneven film. A more preferable range of the thickness of the uneven film is 0.3 μm or more and 1.2 μm or less.
図4に示すように、球状フィラーのない平滑面から凸部の最上部までを凸部高さと定義する。図5に示すように粒子が凝集していたり、密に充填されていたりした場合は、表面粗度計で測った最下面を平滑面とみなし、表面に現れている各粒子について1つずつ凸部高さを考慮する。本発明では、凸部高さが30nm以上3000nm以下のものが全凸部の70%以上であることが望ましい。ここで全凸部とは、フィラーにより表面が平滑面より高くなっている全領域のことである。凸部高さが30nmより低い場合は、十分な光閉じ込め効果が得られ難くなる。凸部高さが3000nmを超えると、太陽電池セル形成時に、太陽電池セルの各層に不均一な応力が加わり膜が剥離したり、セルが短絡したりし易くなる。凸部高さのより好ましい範囲は、200nm以上2000nm以下、さらに好ましい範囲は300nm以上1500nm以下である。また、凸部高さが30nm以上3000nm以下のものが全凸部の70%より少ない場合は、十分な光閉じ込め効果が得られなかったり、セルの短絡が起きたり剥離が生じたりする恐れが高まる。凸部高さが30nm以上3000nm以下のものが全凸部の80%以上であるとき、特に好ましい効果が得られる。 As shown in FIG. 4, the height from the smooth surface without the spherical filler to the top of the convex portion is defined as the convex portion height. If the particles are agglomerated or densely packed as shown in FIG. 5, the bottom surface measured by the surface roughness meter is regarded as a smooth surface, and one particle is projected for each particle appearing on the surface. Consider the height of the part. In the present invention, it is desirable that the height of the convex portion is 30 nm or more and 3000 nm or less is 70% or more of the total convex portion. Here, the total convex portion is the entire region whose surface is higher than the smooth surface by the filler. When the height of the convex portion is lower than 30 nm, it is difficult to obtain a sufficient light confinement effect. If the height of the convex part exceeds 3000 nm, non-uniform stress is applied to each layer of the solar battery cell when the solar battery cell is formed, and the film is easily peeled off or the cell is easily short-circuited. A more preferable range of the height of the convex portion is 200 nm or more and 2000 nm or less, and a more preferable range is 300 nm or more and 1500 nm or less. In addition, when the height of the convex portion is 30 nm or more and 3000 nm or less is less than 70% of the total convex portion, there is a high possibility that sufficient light confinement effect cannot be obtained, cell short-circuiting or peeling occurs. . A particularly preferable effect is obtained when the height of the convex portion is 30 nm or more and 3000 nm or less is 80% or more of the total convex portion.
本発明の凹凸膜の凸部径は、図4に示すように凸部を形成している球状フィラーを真球とみなし、凸部の曲率から求めた球の直径と定義する。球状フィラーが凝集しているときは、表面に現れている形状から、それぞれの球状フィラーについて凸部径を求めることができる。本発明では、凸部径が50nm以上3000nm以下のものが全凸部の70%以上であることが望ましい。凸部径が50nmより小さい場合、及び、3000nmを超える場合のどちらも、十分な光閉じ込め効果が得られ難くなる。凸部径のより好ましい範囲は、300nm以上2500nm以下、さらに好ましい範囲は450nm以上2000nm以下である。また、凸部径が50nm以上3000nm以下のものが全凸部の70%より少ない場合は、十分な光閉じ込め効果が得られ難くなる。凸部径が50nm以上3000nm以下のものが全凸部の80%以上であるとき、特に好ましい効果が得られる。 The convex part diameter of the concavo-convex film of the present invention is defined as the diameter of a sphere obtained from the curvature of the convex part, assuming that the spherical filler forming the convex part is a true sphere as shown in FIG. When the spherical filler is agglomerated, the convex diameter can be obtained for each spherical filler from the shape appearing on the surface. In the present invention, it is desirable that the convex part diameter is 50 nm or more and 3000 nm or less and 70% or more of the total convex part. It is difficult to obtain a sufficient light confinement effect both when the diameter of the convex portion is smaller than 50 nm and when it exceeds 3000 nm. A more preferable range of the convex portion diameter is 300 nm to 2500 nm, and a more preferable range is 450 nm to 2000 nm. Further, when the convex part diameter is 50 nm or more and 3000 nm or less is less than 70% of the total convex part, it is difficult to obtain a sufficient light confinement effect. A particularly preferable effect is obtained when the diameter of the convex portion is 50 nm or more and 3000 nm or less is 80% or more of the total convex portion.
本発明の凸部面積は、フィラーにより平滑面より高くなっている部分の面積と定義する。この面積が全基板面積の10%より少ない場合および90％より多い場合は、十分な光閉じ込め効果が得られ難くなる。凸部面積のより好ましい範囲は全基板面積の20%以上80％以下、さらに好ましい範囲は30％以上70%以下である。 The convex part area of the present invention is defined as the area of the part higher than the smooth surface by the filler. When this area is less than 10% of the total substrate area and more than 90%, it is difficult to obtain a sufficient light confinement effect. A more preferable range of the convex area is 20% to 80% of the total substrate area, and a more preferable range is 30% to 70%.
下地膜を構成する無機ポリマーのシロキサン骨格を修飾する有機基は、耐熱性が高く、適度な膜硬度が得られると言う点において、メチル基又はフェニル基の一方又は両方であることが望ましい。さらに、シロキサン骨格を修飾する有機基のシロキサン骨格を形成している全Siに対するモル比は、1以上2.2以下であることが望ましい。この比が1より小さい場合は、有機基による膜の柔軟化の効果が小さいため、クラックが入り易くなる。2.2より大きい場合は、膜が柔らかくなり過ぎるため、太陽電池セルの形成に支障が出易くなる。 The organic group that modifies the siloxane skeleton of the inorganic polymer constituting the base film is preferably one or both of a methyl group and a phenyl group in that heat resistance is high and appropriate film hardness can be obtained. Further, the molar ratio of the organic group that modifies the siloxane skeleton to the total Si forming the siloxane skeleton is preferably 1 or more and 2.2 or less. If this ratio is less than 1, the effect of softening the film by the organic group is small, and cracks are likely to occur. When the ratio is larger than 2.2, the film becomes too soft, and thus the formation of solar cells is likely to be hindered.
凹凸膜中の球状フィラーは、マトリックスの無機ポリマーとの密着性が良好である上、球状で適当な粒径のものが得られ易いため、コロイダルシリカであることが望ましい。また、球状フィラーを含んでいる無機ポリマー膜は、全Siに対してエポキシ基をモル比で0.2以上0.7以下含むシリカ系無機ポリマーであることが望ましい。エポキシ基の比率が0.2より少ない場合は、球状フィラーが凹凸表面から欠落し易い傾向がある。微結晶シリコン薄膜太陽電池は通常200℃以上の成膜温度を必要とするので、エポキシ基の比率が0.7を超えると、太陽電池形成中にエポキシ基の分解に伴う脱ガス等で、セルが剥離したり、太陽電池特性が劣化したりする恐れが生じ易い。 The spherical filler in the concavo-convex film is preferably colloidal silica because it has good adhesion to the matrix inorganic polymer and can be easily obtained in a spherical shape with an appropriate particle size. In addition, the inorganic polymer film containing the spherical filler is preferably a silica-based inorganic polymer containing epoxy groups in a molar ratio of 0.2 to 0.7 with respect to the total Si. When the ratio of epoxy groups is less than 0.2, the spherical filler tends to be lost from the uneven surface. Microcrystalline silicon thin-film solar cells usually require a deposition temperature of 200 ° C or higher, so if the epoxy group ratio exceeds 0.7, the cells will peel off due to degassing accompanying the decomposition of the epoxy groups during solar cell formation. Or the solar cell characteristics are likely to deteriorate.
本発明のシロキサン結合を主体とする無機ポリマーから成る下地膜は、ポリシロキサンとSi、Al、Ti、Zr、Nb、Ta、Wから選ばれる1種類以上の金属アルコキシドを出発原料として、加水分解して調製したゾルをステンレス箔に塗布し、乾燥・焼き付けすることにより作製することができる。ポリシロキサンとしては、ポリジメチルシロキサン、ポリメチルフェニルシロキサン、ポリジフェニルシロキサン、ポリジメチルジフェニルシロキサン等が挙げられる。ポリシロキサンの両末端は、シラノール基の他、カルビノール変性、アミノ変性等でもよい。ポリシロキサンの質量平均分子量は500以上15000以下であることが望ましく、特に2500以上10000以下であることが望ましい。質量平均分子量が500より小さい場合は、低粘度の塗布液となるため、十分な膜厚を得ることが難しい。質量平均分子量が15000を超える場合は、膜硬化に時間がかかる上、得られる膜も柔らかく傷つき易い。ポリジメチルシロキサン中のSiに対するSi、Al、Ti、Zr、Nb、Ta、Wから選ばれる1種類以上の金属アルコキシドのモル比が1/40以上1/4以下であるように、有機溶媒中に分散させてから加水分解させることが特に望ましい。ポリジメチルシロキサン中のSiに対する金属アルコキシドのモル比が1/40より小さい場合は、三次元網目構造が発達し難いため、膜の硬化が不十分になり易い。このモル比が1/4を超える場合は、膜が硬くなり過ぎるため、クラックが入り易い。Siのアルコキシドとしては、テトラエトキシシラン、テトラメトキシシランの他に、オルガノアルコキシシランを用いることができる。オルガノアルコキシシランとしては、メチルトリメトキシシラン、メチルトリエトキシシラン、エチルトリメトキシシラン、エチルトリエトキシシラン、プロピルトリメトキシシラン、プロピルトリエトキシシラン、イソブチルトリメトキシシラン、イソブチルトリエトキシシラン、ジメトキシジメチルシラン、ジエトキシジメチルシラン、フェニルトリメトキシシラン、フェニルトリエトキシシラン、メタクリロキシプロピルトリメトキシシラン、メタクリロキシプロピルトリエトキシシラン、グリシドキシプロピルトリメトキシシラン、グリシドキシプロピルトリエトキシシラン、アミノプロピルトリメトキシシラン、アミノプロピルトリエトキシシラン等が挙げられる。Al、Ti、Zr、Nb、Ta、Wの金属アルコキシドは、いずれもアルコキシシランに比べて反応性が高いため、アルコキシ基の一部をβ-ジケトン、β-ケトエステル、アルカノールアミン、アルキルアルカノールアミン、有機酸等で置換したアルコキシド誘導体を使用してもよい。 The base film made of an inorganic polymer mainly composed of siloxane bonds of the present invention is hydrolyzed using polysiloxane and one or more metal alkoxides selected from Si, Al, Ti, Zr, Nb, Ta, and W as starting materials. The sol thus prepared can be applied to a stainless steel foil, dried and baked. Examples of the polysiloxane include polydimethylsiloxane, polymethylphenylsiloxane, polydiphenylsiloxane, polydimethyldiphenylsiloxane, and the like. Both ends of the polysiloxane may be modified with carbinol or amino, in addition to a silanol group. The mass average molecular weight of the polysiloxane is preferably 500 or more and 15000 or less, and particularly preferably 2500 or more and 10,000 or less. When the mass average molecular weight is smaller than 500, it becomes a low-viscosity coating solution, and it is difficult to obtain a sufficient film thickness. When the mass average molecular weight exceeds 15000, it takes time to cure the film, and the resulting film is also soft and easily damaged. In the organic solvent, the molar ratio of one or more metal alkoxides selected from Si, Al, Ti, Zr, Nb, Ta, W to Si in polydimethylsiloxane is 1/40 or more and 1/4 or less. It is particularly desirable to hydrolyze after dispersing. When the molar ratio of the metal alkoxide to Si in the polydimethylsiloxane is less than 1/40, the three-dimensional network structure is difficult to develop, and the film tends to be insufficiently cured. If this molar ratio exceeds 1/4, the film becomes too hard and cracks are likely to occur. As Si alkoxide, organoalkoxysilane can be used in addition to tetraethoxysilane and tetramethoxysilane. Examples of the organoalkoxysilane include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, isobutyltrimethoxysilane, isobutyltriethoxysilane, dimethoxydimethylsilane, Diethoxydimethylsilane, phenyltrimethoxysilane, phenyltriethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropyltriethoxysilane, glycidoxypropyltrimethoxysilane, glycidoxypropyltriethoxysilane, aminopropyltrimethoxysilane And aminopropyltriethoxysilane. Since all metal alkoxides of Al, Ti, Zr, Nb, Ta, and W are more reactive than alkoxysilane, some alkoxy groups are β-diketone, β-ketoester, alkanolamine, alkylalkanolamine, An alkoxide derivative substituted with an organic acid or the like may be used.
前述したアルコキシド、ポリシロキサン等の膜固形分を生成するための出発原料を均一に分散、溶解できる有機溶媒中で、加水分解を行い、ゾルを調製することができる。有機溶媒として、例えば、メタノール、エタノール、プロパノール、ブタノール等の各種アルコール、アセトン、トルエン、キシレン等を用いることができる。 A sol can be prepared by performing hydrolysis in an organic solvent capable of uniformly dispersing and dissolving the starting material for producing the above-described film solids such as alkoxide and polysiloxane. As the organic solvent, for example, various alcohols such as methanol, ethanol, propanol and butanol, acetone, toluene, xylene and the like can be used.
加水分解は、出発原料中の全アルコキシ基のモル数に対して0.5〜2倍の水を添加して行う。必要に応じて、加水分解の触媒として酸を添加してもよい。酸としては、無機酸、有機酸とも使用可能である。 Hydrolysis is performed by adding 0.5 to 2 times as much water as the number of moles of all alkoxy groups in the starting material. If necessary, an acid may be added as a hydrolysis catalyst. As the acid, both inorganic acids and organic acids can be used.
本発明の凹凸膜は、金属アルコキシドを有機溶媒中で加水分解したゾルの中に球状フィラーを添加したものを、ステンレス箔上に形成した下地膜の上に塗布し、乾燥・焼き付けにより作製することができる。このとき、下地膜については、塗布後、乾燥のみであっても、乾燥・焼き付けを終了したものであってもよい。下地膜が乾燥のみで凹凸膜形成用のゾルを塗布した場合は、凹凸膜の焼き付け時に下地膜も同時に焼き付けることになる。 The uneven film of the present invention is prepared by applying a sol obtained by hydrolyzing a metal alkoxide in an organic solvent to which a spherical filler is added on a base film formed on a stainless steel foil, followed by drying and baking. Can do. At this time, the base film may be only dried after coating, or may be dried and baked. When a sol for forming a concavo-convex film is applied only by drying the base film, the base film is baked at the same time when the concavo-convex film is baked.
粒径50nm以上5000nm以下の球状フィラーとしては、シリカ、アルミナ、チタニア等の材質のフィラーが挙げられる。コロイダルシリカのように、溶媒中に分散したシリカ粒子であってもよい。また、メチルトリエトキシシランを有機溶媒中で加水分解して得られるメチル基含有シリカガラスのような無機・有機ハイブリッド粒子であってもよい。球状フィラーは、直径の最長と最短の比が0.6以上であれば、完全な球でなくてもよい。 Examples of the spherical filler having a particle size of 50 nm or more and 5000 nm or less include fillers made of materials such as silica, alumina, and titania. Silica particles dispersed in a solvent, such as colloidal silica, may be used. Alternatively, inorganic / organic hybrid particles such as methyl group-containing silica glass obtained by hydrolyzing methyltriethoxysilane in an organic solvent may be used. The spherical filler may not be a perfect sphere as long as the ratio of the longest diameter to the shortest diameter is 0.6 or more.
球状フィラーを分散させるゾルは、Siのアルコキシド又はオルガノアルコキシシランを有機溶媒中で加水分解することにより調製できる。その際、加水分解促進のための触媒として、Al、Ti、Zr、Nb、Ta、W等の金属アルコキシドを添加してもよい。グリシドキシプロピルトリエトキシシラン、グリシドキシプロピルトリメトキシシラン等を用いることにより、球状フィラーのマトリックス部分にエポキシ基を導入することが可能となる。球状フィラーがゾルの中で良好に分散させられるように、加水分解時の水に酸・アルカリ等を添加して、pH調整してもよい。球状フィラーの分散性がよいと、凝集による二次粒子ができ難いので、凸部高さを3000nm以下にそろえることが容易になる。 The sol in which the spherical filler is dispersed can be prepared by hydrolyzing Si alkoxide or organoalkoxysilane in an organic solvent. At that time, metal alkoxides such as Al, Ti, Zr, Nb, Ta, and W may be added as a catalyst for promoting hydrolysis. By using glycidoxypropyltriethoxysilane, glycidoxypropyltrimethoxysilane, or the like, it becomes possible to introduce an epoxy group into the matrix portion of the spherical filler. The pH may be adjusted by adding acid, alkali, or the like to the water during hydrolysis so that the spherical filler is well dispersed in the sol. If the dispersibility of the spherical filler is good, it is difficult to form secondary particles due to aggregation, so that it becomes easy to adjust the height of the convex portion to 3000 nm or less.
ステンレス箔へのコーティングは、バーコート法、ロールコート法、スプレーコート法、ディップコート法、スピンコート法等で行うことができる。特に、ステンレス箔がコイル形状の場合は、オフセット方式又はグラビア方式によるロールコータで塗布することが連続処理が容易で好ましい。ステンレス箔に対して、特に前処理を行わなくても良好な密着性を示すが、必要に応じて、塗布前に前処理を行うこともできる。代表的な前処理としては、酸洗、アルカリ脱脂、クロメート等の化成処理、研削、研磨、ブラスト処理等があり、必要に応じてこれらを単独もしくは組み合わせて行うことができる。 Coating on the stainless steel foil can be performed by a bar coating method, a roll coating method, a spray coating method, a dip coating method, a spin coating method, or the like. In particular, when the stainless steel foil has a coil shape, it is preferable to apply with a roll coater by an offset method or a gravure method because continuous processing is easy. The stainless steel foil exhibits good adhesion without any pretreatment, but it can be pretreated before application, if necessary. Typical pretreatment includes pickling, alkali degreasing, chemical conversion treatment such as chromate, grinding, polishing, blasting, and the like, and these can be performed alone or in combination as necessary.
ステンレス箔材としては、フェライト系ステンレス箔、マルテンサイト系ステンレス箔、オーステナイト系ステンレス箔等が挙げられる。ステンレス箔の表面は、ブライトアニール、バフ研磨等の表面処理を施してあってもよい。 Examples of the stainless steel foil material include ferritic stainless steel foil, martensitic stainless steel foil, and austenitic stainless steel foil. The surface of the stainless steel foil may be subjected to a surface treatment such as bright annealing or buffing.
本発明の被覆ステンレス箔を基板に用いた場合、例えば、Al電極、n型シリコン層、活性層となるi層、p型シリコン層、ITO膜を順次積層し、最後に、くし型電極を形成して薄膜微結晶シリコンによる太陽電池セルを作製することができる。本発明によれば、従来のSnO2テクスチャ付きガラス基板と同等の特性の太陽電池が、被覆ステンレス箔上に形成可能となる。被覆ステンレス箔は、ガラス基板に比べて、軽量で割れ難く、大面積化が容易であるので、屋根等の建材向けの太陽電池基板として適している。また、フレキシブル太陽電池としての応用も期待される。 When the coated stainless steel foil of the present invention is used for a substrate, for example, an Al electrode, an n-type silicon layer, an i layer serving as an active layer, a p-type silicon layer, and an ITO film are sequentially laminated, and finally a comb-shaped electrode is formed. Thus, a solar battery cell using thin film microcrystalline silicon can be manufactured. According to the present invention, a solar cell having characteristics equivalent to those of a conventional SnO 2 textured glass substrate can be formed on the coated stainless steel foil. Since the coated stainless steel foil is lighter and harder to break than a glass substrate and can be easily increased in area, it is suitable as a solar cell substrate for building materials such as a roof. Moreover, application as a flexible solar cell is also expected.
アセト酢酸エチル2モルとテトラエトキシチタン1モルを2モルのエタノールに分散させ、両末端カルビノール変性で平均分子量6000のポリジメチルジフェニルシロキサン0.2モル加え攪拌した。4モルの2-エトキシエタノールと2モルの水の混合溶液を滴下し、ゾルを調製した。厚さ100μm、表面をスーパーブライトで仕上げたYUS190(SUS444規格相当)の基板の上に、番手26番のバーコータで塗布し、150℃で2分乾燥後、150℃で2時間、続いて300℃で6時間の熱処理を行い、下地膜を作製した。得られた下地膜の厚さは約7μmであった。 2 moles of ethyl acetoacetate and 1 mole of tetraethoxytitanium were dispersed in 2 moles of ethanol, and 0.2 moles of polydimethyldiphenylsiloxane having an average molecular weight of 6000 modified with carbinol at both ends was added and stirred. A mixed solution of 4 mol of 2-ethoxyethanol and 2 mol of water was added dropwise to prepare a sol. It is coated on a YUS190 (SUS444 standard) substrate with a thickness of 100μm and finished with Super Bright, using a number 26 bar coater, dried at 150 ° C for 2 minutes, then 150 ° C for 2 hours, then 300 ° C. A base film was prepared by heat treatment for 6 hours. The thickness of the obtained base film was about 7 μm.
次に、テトラエトキシチタン0.07モルと酢酸0.21モルとグリシドキシプロピルトリエトキシシラン0.7モルを24時間混合後、テトラエトキシシラン0.3モルを添加し、1モルの水と6モルのエタノールを混合した溶液をゆっくりと添加して、加水分解を行った。得られた加水分解溶液5.80gに対して，アミノプロピルトリエトキシシランを0.77g添加して溶液Aを作製した。この溶液Aに対して、種々のフィラーを添加し、粘度調整等の目的で、必要に応じて水とエタノールの混合溶液を適宜加え、エポキシ基含有シリカ系ゾルを調製した。得られたゾルを番手3番のバーコータで下地膜上に塗布し、100℃5分で乾燥後、250℃5分で焼き付けて、凹凸膜を作製した。形成した凹凸膜の厚みはいずれも0.7μmから0.9μmの間にあった。 Next, 0.07 mol of tetraethoxytitanium, 0.21 mol of acetic acid and 0.7 mol of glycidoxypropyltriethoxysilane were mixed for 24 hours, then 0.3 mol of tetraethoxysilane was added, and 1 mol of water and 6 mol of ethanol were mixed. Was added slowly to effect hydrolysis. Solution A was prepared by adding 0.77 g of aminopropyltriethoxysilane to 5.80 g of the obtained hydrolysis solution. Various fillers were added to the solution A, and a mixed solution of water and ethanol was appropriately added as necessary for the purpose of adjusting the viscosity, etc., to prepare an epoxy group-containing silica-based sol. The obtained sol was applied onto the base film with a No. 3 bar coater, dried at 100 ° C. for 5 minutes, and baked at 250 ° C. for 5 minutes to prepare an uneven film. The thickness of the formed uneven film was between 0.7 μm and 0.9 μm.
作製した凹凸膜を有するステンレス箔について、ステンレス箔を下部電極とし、凹凸膜上に1cm2の上部電極をつけて、印加電圧500Vで絶縁抵抗を測定した。また、作製したステンレス箔を基板として、凹凸膜の上に太陽電池セルを形成し、SnO2によるテクスチャーつきガラス基板上に作製した太陽電池セルと効率の比較を行った。効率が1の場合、テクスチャーつきガラス基板と同等の性能であり、1を超えた場合はそれよりも効率が高いことを意味する。結果を表1に示す。 With respect to the produced stainless steel foil having an uneven film, the insulation resistance was measured at an applied voltage of 500 V by using the stainless steel foil as a lower electrode, attaching a 1 cm 2 upper electrode on the uneven film. Further, using the produced stainless steel foil as a substrate, solar cells were formed on the uneven film, and the efficiency was compared with the photovoltaic cells produced on a glass substrate with a texture of SnO 2 . When the efficiency is 1, the performance is the same as that of the textured glass substrate, and when it exceeds 1, the efficiency is higher than that. The results are shown in Table 1.
コロイダルシリカとしては、日産化学製コロイダルシリカOMP2030(粒子径200nm、PH2.2、SiO2:30.5質量%)、OMP3030(粒子径300nm、PH2.2、SiO2:30.5質量%)、OMP4530(粒子径450nm、pH3.0、SiO2:30.5質量%)を用いた。球状シリカ（１）は電気化学工業製SFP-30Mを用いた。球状アルミナはアドマテックス製AO-502を用いた。球状シリコーンは日硝産業トスパール120を用いた。球状シリア（２）はマイクロン製SC10-2である。SiCウィスカーは、東海カーボン製トーカウィスカーを用いた。フュームドシリカはアエロジル製AEROSILTM200を用いた。 The colloidal silica, manufactured by Nissan Chemical Industries, Ltd. colloidal silica OMP2030 (particle size 200nm, PH2.2, SiO 2: 30.5 wt%), OMP3030 (particle size 300nm, PH2.2, SiO 2: 30.5 wt%), OMP4530 (particle size 450 nm, pH 3.0, SiO 2 : 30.5 mass%) was used. As the spherical silica (1), SFP-30M manufactured by Denki Kagaku Kogyo was used. The spherical alumina used was AO-502 manufactured by Admatechs. As the spherical silicone, Nissho Sangyo Tospearl 120 was used. Spherical Syria (2) is SC10-2 made by Micron. Tokai whiskers made by Tokai Carbon were used as SiC whiskers. AEROSIL ™ 200 manufactured by Aerosil was used as the fumed silica.
比較例１は十分な凹凸を得ることができず効率が低かった。比較例２は凹凸が荒すぎるため良好なセルを形成することができず効率が低かった。比較例3、4、6においては、太陽電池のセル形成時、セル形成部に剥離が生じた。比較例5では、絶縁膜として機能していないため、太陽電池セルを直列接続等することができなかった。 In Comparative Example 1, sufficient unevenness could not be obtained and the efficiency was low. In Comparative Example 2, since the unevenness was too rough, a good cell could not be formed and the efficiency was low. In Comparative Examples 3, 4, and 6, peeling occurred in the cell formation portion when the solar cell was formed. In Comparative Example 5, the solar cells could not be connected in series because they did not function as an insulating film.
11 球状フィラー
12 凹凸表面
21 球状フィラー
22 凹凸表面
23 オーバーハング領域
41及び42 球状フィラー
43 凹凸表面
44 球状フィラー41の凸部高さ
45 球状フィラー42の凸部高さ
51及び52 球状フィラー
53 凹凸表面
54 みなしの平滑面
55 球状フィラー51の凸部高さ
56 球状フィラー52の凸部高さ
11 Spherical filler
12 Uneven surface
21 Spherical filler
22 Uneven surface
23 Overhang area
41 and 42 Spherical filler
43 Uneven surface
44 Convex height of spherical filler 41
45 Convex height of spherical filler 42
51 and 52 Spherical filler
53 Uneven surface
54 Deemed smooth surface
55 Convex height of spherical filler 51
56 Convex height of spherical filler 52
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| JP2007088044A (en) * | 2005-09-20 | 2007-04-05 | Nippon Steel Materials Co Ltd | Coated stainless steel foil and thin film solar cell |
| JP2008235474A (en) * | 2007-03-19 | 2008-10-02 | Nippon Steel Materials Co Ltd | Insulator coated stainless steel foil for amorphous-silicon solar cell and manufacturing method thereof |
| JP2008255242A (en) * | 2007-04-05 | 2008-10-23 | Nippon Steel Materials Co Ltd | Coating solution for forming flat-surface insulation film, substrate coated with flat-surface insulation film, and method for producing substrate coated with flat-surface insulation film |
| WO2012077827A1 (en) | 2010-12-10 | 2012-06-14 | Ｊｆｅスチール株式会社 | Steel foil for solar cell substrate, solar cell substrate, solar cell, and methods for manufacturing the steel foil and the solar cell |
| JP2013518145A (en) * | 2010-01-25 | 2013-05-20 | エルジー・ケム・リミテッド | Photovoltaic sheet |
| JP2018062582A (en) * | 2016-10-13 | 2018-04-19 | 新日鉄住金マテリアルズ株式会社 | Method for adjusting viscosity of film-forming coating liquid |
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| JP2002097365A (en) * | 2000-09-25 | 2002-04-02 | Nisshin Steel Co Ltd | Insulating substrate for thin-film polycrystal silicon solar battery, and method for producing the same |
| JP2003264302A (en) * | 2002-03-11 | 2003-09-19 | Nisshin Steel Co Ltd | Insulating substrate for thin film solar battery superior in dielectric strength |
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| JP2002097365A (en) * | 2000-09-25 | 2002-04-02 | Nisshin Steel Co Ltd | Insulating substrate for thin-film polycrystal silicon solar battery, and method for producing the same |
| JP2003264302A (en) * | 2002-03-11 | 2003-09-19 | Nisshin Steel Co Ltd | Insulating substrate for thin film solar battery superior in dielectric strength |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2007088044A (en) * | 2005-09-20 | 2007-04-05 | Nippon Steel Materials Co Ltd | Coated stainless steel foil and thin film solar cell |
| JP2008235474A (en) * | 2007-03-19 | 2008-10-02 | Nippon Steel Materials Co Ltd | Insulator coated stainless steel foil for amorphous-silicon solar cell and manufacturing method thereof |
| JP2008255242A (en) * | 2007-04-05 | 2008-10-23 | Nippon Steel Materials Co Ltd | Coating solution for forming flat-surface insulation film, substrate coated with flat-surface insulation film, and method for producing substrate coated with flat-surface insulation film |
| JP2013518145A (en) * | 2010-01-25 | 2013-05-20 | エルジー・ケム・リミテッド | Photovoltaic sheet |
| WO2012077827A1 (en) | 2010-12-10 | 2012-06-14 | Ｊｆｅスチール株式会社 | Steel foil for solar cell substrate, solar cell substrate, solar cell, and methods for manufacturing the steel foil and the solar cell |
| KR20140074248A (en) | 2010-12-10 | 2014-06-17 | 제이에프이 스틸 가부시키가이샤 | Steel foil for solar cell substrate, solar cell substrate, solar cell, and methods for manufacturing the steel foil and the solar cell |
| JP2018062582A (en) * | 2016-10-13 | 2018-04-19 | 新日鉄住金マテリアルズ株式会社 | Method for adjusting viscosity of film-forming coating liquid |
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