JP2012231171A - Method for formation of solar battery electrode, and solar battery with electrode produced by the method - Google Patents
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Abstract
Description
本発明は、太陽電池の電極を形成する方法及び該形成方法により得られた電極を用いた太陽電池に関するものである。 The present invention relates to a method for forming an electrode of a solar cell and a solar cell using an electrode obtained by the forming method.
従来、導電性ペーストなどの金属微粒子を含有する原料を用いて半導体基材上へ金属電極を形成する方法として、酸化銀、炭酸銀、酢酸銀などの粒子状銀化合物と還元剤とバインダを含む導電性組成物を塗布し、加熱して導電性被膜を形成する方法が開示されている（例えば、特許文献１参照。）。特許文献１によれば、高温の成膜条件に依らずとも、金属銀に匹敵する低体積抵抗率、高導電性の導電性被膜が得られる。 Conventionally, as a method of forming a metal electrode on a semiconductor substrate using a raw material containing fine metal particles such as a conductive paste, a particulate silver compound such as silver oxide, silver carbonate, and silver acetate, a reducing agent, and a binder are included. A method of applying a conductive composition and heating to form a conductive film is disclosed (for example, see Patent Document 1). According to Patent Document 1, a conductive film having a low volume resistivity and high conductivity comparable to metallic silver can be obtained without depending on high temperature film formation conditions.
また、有機バインダーと、溶剤と、ガラスフリットと、導電性粉末とを含んでなる導電性ペーストにおいて、Ｔｉ、Ｂｉ、Ｚｎ、Ｙ、Ｉｎ及びＭｏから選ばれる少なくとも１種の金属又はその金属化合物の粉末を含み、その平均粒径が０．００１μｍ以上０．１μｍ未満である導電性ペーストと、この導電性ペーストをシリコン半導体の反射防止層上に印刷又は塗布した後に、焼成することで太陽電池を製造する方法が開示されている（例えば、特許文献２参照。）。上記特許文献２に示される導電性ペーストでは、この導電性ペーストを印刷又は塗布した基板を５５０〜８５０℃の温度で焼成して電極を形成することが好適である。特許文献２によれば、超微粒子の添加剤を均一に分散させたものであって、これを焼成することで、反射防止層を介して存在する半導体と導電性ペーストとの間に安定した高い導通性と優れた接着力を有する表面電極を形成することができる。 Further, in a conductive paste comprising an organic binder, a solvent, glass frit, and conductive powder, at least one metal selected from Ti, Bi, Zn, Y, In and Mo or a metal compound thereof A conductive paste containing a powder and having an average particle size of 0.001 μm or more and less than 0.1 μm, and printing or coating the conductive paste on the antireflection layer of a silicon semiconductor, followed by firing to produce a solar cell A manufacturing method is disclosed (for example, see Patent Document 2). In the conductive paste disclosed in Patent Document 2, it is preferable to form an electrode by firing a substrate on which the conductive paste is printed or applied at a temperature of 550 to 850 ° C. According to Patent Document 2, the additive of ultrafine particles is uniformly dispersed, and by firing this, a stable high between the semiconductor and the conductive paste existing through the antireflection layer A surface electrode having electrical conductivity and excellent adhesion can be formed.
しかしながら、上記特許文献１に示される方法では、バルク金属に近い体積抵抗率を有する金属被膜からなる電極が得られるものの、基材との密着性の高い被膜を得ることが困難であった。
また、上記特許文献２に示される方法では、ガラスフリットの溶融が必要となることから、代表的なガラスフリットとして挙げられるホウケイ酸ガラスの軟化温度である３００℃以上の温度で焼成する必要があり、特許文献２で好適とされる焼成温度も高く、例えば太陽電池用アモルファスシリコン基材へ接合する場合では、変換効率を悪化させるなどの悪影響を及ぼす問題がある。また、大半の樹脂類の耐熱温度を上回る焼成温度であることから、樹脂類をベースとする基材への適用が困難であった。
However, in the method disclosed in Patent Document 1, although an electrode made of a metal film having a volume resistivity close to that of a bulk metal can be obtained, it is difficult to obtain a film having high adhesion to the substrate.
Further, in the method disclosed in Patent Document 2, it is necessary to melt glass frit. Therefore, it is necessary to perform baking at a temperature of 300 ° C. or higher which is a softening temperature of borosilicate glass exemplified as a typical glass frit. The firing temperature suitable for Patent Document 2 is also high. For example, when bonding to an amorphous silicon substrate for solar cells, there is a problem of adversely affecting conversion efficiency. In addition, since the firing temperature is higher than the heat resistance temperature of most resins, it has been difficult to apply to base materials based on resins.
本発明の目的は、基材との密着性に優れた電極を形成し得る、太陽電池の電極の形成方法及び該形成方法により得られた電極を用いた太陽電池を提供することにある。
本発明の別の目的は、導電性に優れた電極を形成し得る、太陽電池の電極の形成方法及び該形成方法により得られた電極を用いた太陽電池を提供することにある。
本発明の更に別の目的は、可視光の反射率が高い電極を形成し得る、太陽電池の電極の形成方法及び該形成方法により得られた電極を用いた太陽電池を提供することにある。
The objective of this invention is providing the solar cell using the electrode formed by the formation method of the electrode of a solar cell which can form the electrode excellent in adhesiveness with a base material, and this formation method.
Another object of the present invention is to provide a method for forming an electrode of a solar cell, which can form an electrode having excellent conductivity, and a solar cell using the electrode obtained by the method.
Still another object of the present invention is to provide a method for forming an electrode of a solar cell, which can form an electrode having a high visible light reflectance, and a solar cell using the electrode obtained by the forming method.
請求項１に係る発明は、電極形成用組成物を基材上に湿式塗工法で塗工して成膜する工程と、上面に成膜された基材を焼成する工程とを含む太陽電池の電極を形成する方法の改良である。その特徴ある構成は、基材にＡｇの金属酸化物を含む塗布物を塗布してプライマー処理を施すところにある。
請求項１に係る発明では、電極形成用組成物を基材上に塗工、焼成して電極を形成する前に、基材に対してＡｇの金属酸化物を含む塗布物の下塗りを行うプライマー処理を施すことで、電極と基材との密着性を向上させることができる。
The invention according to claim 1 is a solar cell comprising a step of applying a composition for forming an electrode on a substrate by a wet coating method to form a film, and a step of firing the substrate formed on the upper surface. It is an improvement of the method of forming an electrode. The characteristic structure is that a primer is applied by applying a coating containing an Ag metal oxide to a substrate .
In the invention according to claim 1, the primer for applying the composition containing the metal oxide of Ag to the base material before applying the electrode-forming composition onto the base material and firing to form the electrode. By performing the treatment, the adhesion between the electrode and the substrate can be improved.
請求項４に係る発明は、請求項１に係る発明であって、電極形成用組成物が金属ナノ粒子が分散媒に分散した組成物であって、金属ナノ粒子が７５重量％以上の銀ナノ粒子を含有し、金属ナノ粒子は炭素骨格が炭素数１〜３である有機分子主鎖の保護剤で化学修飾され、金属ナノ粒子が一次粒径１０〜５０ｎｍの範囲内の金属ナノ粒子を数平均で７０％以上含有する太陽電池の電極の形成方法である。
請求項４に係る発明では、上記電極形成用組成物を使用することで、導電性に優れ、可視光の反射率が高い電極を４００℃以下の低温での焼成で形成することができる。
The invention according to claim 4 is the invention according to claim 1, wherein the electrode-forming composition is a composition in which metal nanoparticles are dispersed in a dispersion medium, and the silver nanoparticles containing 75% by weight or more of metal nanoparticles. The metal nanoparticles are chemically modified with an organic molecular main chain protective agent having a carbon skeleton of 1 to 3 carbon atoms, and the metal nanoparticles are a number of metal nanoparticles having a primary particle size of 10 to 50 nm. It is the formation method of the electrode of the solar cell which contains 70% or more on average.
In the invention which concerns on Claim 4 , by using the said composition for electrode formation, it is excellent in electroconductivity and can form an electrode with a high reflectance of visible light by baking at the low temperature of 400 degrees C or less.
本発明の太陽電池の電極の形成方法は、電極形成用組成物を基材上に塗工、焼成して電極を形成する前に、基材に対してＡｇの金属酸化物を含む塗布物の下塗りを行うプライマー処理を施すことで、形成する電極と基材との密着性を向上させることができる。従って、基材に導電性材料を用いた場合には、プライマー処理に使用する塗布物中の組成や量を調整することで、電気的接合に優れた電極を得ることができる。また本発明の太陽電池の電極の形成方法で用いる電極形成用組成物は、分散媒に分散された金属ナノ粒子が７５重量％以上の銀ナノ粒子を含有し、炭素骨格が炭素数１〜３の有機分子主鎖の保護剤で金属ナノ粒子を化学修飾し、更に金属ナノ粒子が一次粒径１０〜５０ｎｍの範囲内の金属ナノ粒子を数平均で７０％以上含有するので、組成物中の金属ナノ粒子の比表面積が比較的減少し、分散媒の占める割合が小さくなる。この電極形成用組成物を基材上に湿式塗工法で塗工して焼成後の厚さが０．１〜２．０μｍとなるように成膜し、この上面に成膜された基材を１３０〜４００℃で焼成すれば、金属ナノ粒子の表面を保護していた分散媒中の有機分子が焼成時の熱により脱離し又は分解し、或いは離脱しかつ分解することにより、実質的に有機物を含有しない銀を主成分とする電極が得られる。この結果、上記電極の形成された太陽電池を長年使用しても、有機物が変質又は劣化するということがなく、導電率及び反射率が高い状態に維持されるので、経年安定性に優れた電極を得ることができる。また４００℃以下の低温での焼成により電極を形成できることから、電極形成の際に消費されるエネルギーを削減できる。更に、４００℃以上の焼成によって熱損傷が引き起こされる太陽電池用ポリシリコンのような半導体基材や樹脂類のような耐熱温度が低い素材をベースとする基材に対して適用することができる。 The method for forming an electrode of a solar cell of the present invention is a method of applying a composition for forming an electrode on a substrate and firing it to form an electrode containing an Ag metal oxide with respect to the substrate before forming the electrode . By performing primer treatment for undercoating, the adhesion between the electrode to be formed and the substrate can be improved. Therefore, when a conductive material is used for the base material, an electrode excellent in electrical joining can be obtained by adjusting the composition and amount in the coated material used for the primer treatment. Moreover, the electrode forming composition used in the method for forming an electrode of a solar cell of the present invention contains 75% by weight or more of silver nanoparticles dispersed in a dispersion medium, and the carbon skeleton has 1 to 3 carbon atoms. The metal nanoparticles are chemically modified with an organic molecular main chain protective agent, and the metal nanoparticles contain metal nanoparticles having a primary particle size of 10 to 50 nm in a number average of 70% or more. The specific surface area of the metal nanoparticles is relatively reduced, and the proportion of the dispersion medium is reduced. The electrode-forming composition was applied onto a substrate by a wet coating method to form a film having a thickness after firing of 0.1 to 2.0 μm. When baked at 130 to 400 ° C., organic molecules in the dispersion medium that protected the surface of the metal nanoparticles are desorbed or decomposed by the heat at the time of calcination, or desorbed and decomposed, so that substantially organic matter is obtained. As a result, an electrode containing silver as a main component and containing no silver is obtained. As a result, even if the solar cell on which the electrode is formed is used for many years, the organic matter is not deteriorated or deteriorated, and the conductivity and reflectance are maintained in a high state, so that the electrode has excellent aging stability. Can be obtained. In addition, since the electrode can be formed by baking at a low temperature of 400 ° C. or lower, energy consumed in forming the electrode can be reduced. Furthermore, it can be applied to a base material based on a material having a low heat-resistant temperature such as a semiconductor base material such as polysilicon for solar cells or a resin in which thermal damage is caused by baking at 400 ° C. or higher.
次に本発明を実施するための形態を説明する。
本発明の太陽電池の電極の形成方法は、電極形成用組成物を基材上に湿式塗工法で塗工して成膜する工程と、上面に成膜された基材を焼成する工程とを含む形成方法である。具体的には、電極形成用組成物を基材上に湿式塗工法で塗工して焼成後の厚さが０．１〜２．０μｍの範囲内となるように成膜する工程と、上面に成膜された基材を１３０〜４００℃で焼成する工程とを含む形成方法である。
Next will be described the shape condition for carrying out the present invention.
The method for forming the electrode of the solar cell of the present invention comprises a step of coating a substrate with the electrode-forming composition by a wet coating method and a step of firing the substrate formed on the upper surface. It is the formation method containing. Specifically, a step of coating the electrode-forming composition on a substrate by a wet coating method and forming a film so that the thickness after firing is in the range of 0.1 to 2.0 μm, and the upper surface And a step of firing the substrate formed into a film at 130 to 400 ° C.
本発明で使用する電極形成用組成物は、金属ナノ粒子が分散媒に分散した組成物である。上記金属ナノ粒子は７５重量％以上、好ましくは８０重量％以上の銀ナノ粒子を含有する。銀ナノ粒子の含有量を全ての金属ナノ粒子１００重量％に対して７５重量％以上の範囲に限定したのは、７５重量％未満ではこの組成物を用いて形成された太陽電池の電極の反射率が低下してしまうからである。また金属ナノ粒子は炭素骨格が炭素数１〜３の有機分子主鎖の保護剤で化学修飾される。金属ナノ粒子を化学修飾する保護剤の有機分子主鎖の炭素骨格の炭素数を１〜３の範囲に限定したのは、炭素数が４以上であると焼成時の熱により保護剤が脱離或いは分解（分離・燃焼）し難く、上記電極内に有機残渣が多く残り、変質又は劣化して電極の導電性及び反射率が低下してしまうからである。更に金属ナノ粒子は一次粒径１０〜５０ｎｍの範囲内の金属ナノ粒子を数平均で７０％以上、好ましくは７５％以上含有する。一次粒径１０〜５０ｎｍの範囲内の金属ナノ粒子の含有量を、数平均で全ての金属ナノ粒子１００％に対して７０％以上の範囲に限定したのは、７０％未満では金属ナノ粒子の比表面積が増大して有機物の占める割合が大きくなり、焼成時の熱により脱離或いは分解（分離・燃焼）し易い有機分子であっても、この有機分子の占める割合が多いため、電極内に有機残渣が多く残り、この残渣が変質又は劣化して電極の導電性及び反射率が低下したり、或いは金属ナノ粒子の粒度分布が広くなり電極の密度が低下し易くなって、電極の導電性及び反射率が低下してしまうからである。更に上記金属ナノ粒子の一次粒径を１０〜５０ｎｍの範囲内に限定したのは、統計的手法より一次粒径が１０〜５０ｎｍの範囲内にある金属ナノ粒子が経時安定性（経年安定性）と相関しているからである。 The composition for electrode formation used in the present invention is a composition in which metal nanoparticles are dispersed in a dispersion medium. The metal nanoparticles contain 75% by weight or more, preferably 80% by weight or more of silver nanoparticles. The content of silver nanoparticles was limited to a range of 75% by weight or more with respect to 100% by weight of all metal nanoparticles. The reflection of solar cell electrodes formed using this composition was less than 75% by weight. This is because the rate drops. The metal nanoparticles are chemically modified with a protective agent having an organic molecular main chain having a carbon skeleton of 1 to 3 carbon atoms. The number of carbons in the carbon skeleton of the organic molecular main chain of the protective agent that chemically modifies the metal nanoparticles was limited to the range of 1 to 3 because the protective agent was released by the heat during firing when the carbon number was 4 or more. Alternatively, it is difficult to be decomposed (separated / burned), and a large amount of organic residue remains in the electrode, resulting in alteration or deterioration, resulting in a decrease in the conductivity and reflectance of the electrode. Further, the metal nanoparticles contain 70% or more, preferably 75% or more of metal nanoparticles having a primary particle size in the range of 10 to 50 nm in terms of number average. The content of the metal nanoparticles in the range of the primary particle size of 10 to 50 nm is limited to a range of 70% or more with respect to 100% of all metal nanoparticles on the number average. The specific surface area increases and the proportion of organic matter increases, and even organic molecules that are easily desorbed or decomposed (separated and burned) by heat during firing have a large proportion of organic molecules. A large amount of organic residue remains, and this residue is altered or deteriorated to reduce the conductivity and reflectance of the electrode, or the particle size distribution of the metal nanoparticles becomes wide and the density of the electrode tends to decrease, so that the conductivity of the electrode This is because the reflectance decreases. Furthermore, the primary particle size of the metal nanoparticles was limited to the range of 10 to 50 nm because the metal nanoparticles having a primary particle size within the range of 10 to 50 nm are stable over time (statistical stability). It is because it correlates.
本発明の太陽電池の電極の形成方法の特徴ある構成は、基材にプライマー処理を施すところにある。電極形成用組成物を基材上に塗工、焼成して電極を形成する前に、基材に対して下塗りを行うプライマー処理を施すことで、電極と基材との密着性を向上させることができる。プライマー処理は、以下のような塗布物を基材上に塗布することにより行われる。プライマー処理に使用する塗布物としては、Ａｇの金属酸化物を含む塗布物が好適である。この金属酸化物としては、Ａｇ2 Ｏが挙げられる。 The characteristic structure of the method for forming the electrode of the solar cell of the present invention is that the substrate is subjected to primer treatment. Improving the adhesion between the electrode and the substrate by applying a primer treatment to undercoat the substrate before applying the electrode-forming composition onto the substrate and firing to form the electrode. Can do. Primer processing is performed by apply | coating the following coating materials on a base material. The coating material used for primer treatment, the coating comprising a metallic oxide of A g is preferred. As the metal oxide, Ag 2 O and the like.
一方、電極形成用組成物を構成する金属ナノ粒子のうち、銀ナノ粒子以外の金属ナノ粒子は、Ａｕ、Ｐｔ、Ｐｄ、Ｒｕ、Ｎｉ、Ｃｕ、Ｓｎ、Ｉｎ、Ｚｎ、Ｃｒ、Ｆｅ及びＭｎからなる群より選ばれた１種又は２種以上の混合組成又は合金組成からなる金属ナノ粒子が好ましい。この銀ナノ粒子以外の金属ナノ粒子は全ての金属ナノ粒子１００重量％に対して０．０２重量％以上かつ２５重量％未満、好ましくは０．０３重量％〜２０重量％含有する。銀ナノ粒子以外の金属ナノ粒子の含有量を全ての金属ナノ粒子１００重量％に対して０．０２重量％以上かつ２５重量％未満の範囲に限定したのは、０．０２重量％未満では特に大きな問題はないけれども、０．０２〜２５重量％の範囲内においては、耐候性試験（温度１００℃かつ湿度５０％の恒温恒湿槽に１０００時間保持する試験）後の電極の導電性及び反射率が耐候性試験前より悪化しないという特徴があり、２５重量％以上では焼成直後の電極の導電性及び反射率が低下し、しかも耐候性試験後の電極が耐候性試験前の電極より導電性及び反射率が低下してしまうからである。 On the other hand, among the metal nanoparticles constituting the electrode forming composition, metal nanoparticles other than silver nanoparticles are composed of Au, Pt, Pd, Ru, Ni, Cu, Sn, In, Zn, Cr, Fe, and Mn. Metal nanoparticles composed of one or two or more mixed compositions or alloy compositions selected from the group are preferred. The metal nanoparticles other than the silver nanoparticles are contained in an amount of 0.02% by weight or more and less than 25% by weight, preferably 0.03% by weight to 20% by weight, based on 100% by weight of all the metal nanoparticles. The content of metal nanoparticles other than silver nanoparticles is limited to the range of 0.02% by weight or more and less than 25% by weight with respect to 100% by weight of all metal nanoparticles. Although there is no major problem, within the range of 0.02 to 25% by weight, the conductivity and reflection of the electrode after the weather resistance test (test kept in a constant temperature and humidity chamber at a temperature of 100 ° C. and a humidity of 50% for 1000 hours) The rate is not worse than before the weather resistance test, and if it is 25% by weight or more, the conductivity and reflectivity of the electrode immediately after firing decrease, and the electrode after the weather resistance test is more conductive than the electrode before the weather resistance test. This is because the reflectance decreases.
また電極形成用組成物中の銀ナノ粒子を含む金属ナノ粒子の含有量は、金属ナノ粒子及び分散媒からなる組成物１００重量％に対して２．５〜９５．０重量％、好ましくは３．５〜９０重量％含有することが好適である。銀ナノ粒子を含む金属ナノ粒子の含有量を金属ナノ粒子及び分散媒からなる組成物１００重量％に対して２．５〜９５．０重量％の範囲としたのは、２．５重量％未満では特に焼成後の電極の特性には影響はないけれども、必要な厚さの電極を得ることが難しく、９５．０重量％を越えると組成物の湿式塗工時にインク或いはペーストとしての必要な流動性を失ってしまうからである。 The content of the metal nanoparticles including silver nanoparticles in the electrode forming composition is 2.5 to 95.0% by weight, preferably 3 to 100% by weight of the composition comprising the metal nanoparticles and the dispersion medium. It is preferable to contain 5 to 90% by weight. The content of the metal nanoparticles including silver nanoparticles is in the range of 2.5 to 95.0% by weight with respect to 100% by weight of the composition comprising the metal nanoparticles and the dispersion medium, and is less than 2.5% by weight. In particular, there is no effect on the characteristics of the electrode after firing, but it is difficult to obtain an electrode having a required thickness. If it exceeds 95.0% by weight, the required flow as an ink or paste during wet coating of the composition Because they lose their sex.
また電極形成用組成物を構成する分散媒は、全ての分散媒１００重量％に対して、１重量％以上、好ましくは２重量％以上の水と、２重量％以上、好ましくは３重量％以上のアルコール類とを含有することが好適である。例えば、分散媒が水及びアルコール類のみからなる場合、水を２重量％含有するときはアルコール類を９８重量％含有し、アルコール類を２重量％含有するときは水を９８重量％含有する。更に分散媒、即ち金属ナノ粒子表面に化学修飾している保護分子は、水酸基（−ＯＨ）又はカルボニル基（−Ｃ＝Ｏ）のいずれか一方又は双方を含有する。水の含有量を全ての分散媒１００重量％に対して１重量％以上の範囲が好適であるとしたのは、１重量％未満では、組成物を湿式塗工法により塗工して得られた膜を低温で焼結し難く、また焼成後の電極の導電性と反射率が低下してしまい、アルコール類の含有量を全ての分散媒１００重量％に対して２重量％以上の範囲が好適であるとしたのは、２重量％未満では、上記と同様に組成物を湿式塗工法により塗工して得られた膜を低温で焼結し難く、また焼成後の電極の導電性と反射率が低下してしまうからである。なお、水酸基（−ＯＨ）が銀ナノ粒子等の金属ナノ粒子を化学修飾する保護剤に含有されると、組成物の分散安定性に優れ、塗膜の低温焼結にも効果的な作用があり、カルボニル基（−Ｃ＝Ｏ）が銀ナノ粒子等の金属ナノ粒子を化学修飾する保護剤に含有されると、上記と同様に組成物の分散安定性に優れ、塗膜の低温焼結にも効果的な作用がある。分散媒に用いる上記アルコール類としては、メタノール、エタノール、プロパノール、ブタノール、エチレングリコール、プロピレングリコール、ジエチレングリコール、グリセロール、イソボニルヘキサノール及びエリトリトールからなる群より選ばれた１種又は２種以上を用いることが好ましい。 The dispersion medium constituting the electrode-forming composition is 1% by weight or more, preferably 2% by weight or more, and 2% by weight or more, preferably 3% by weight or more with respect to 100% by weight of all the dispersion media. It is preferable to contain these alcohols. For example, when the dispersion medium is composed of only water and alcohols, it contains 98% by weight of alcohol when it contains 2% by weight of water and 98% by weight of water when it contains 2% by weight of alcohol. Further, the dispersion medium, that is, the protective molecule chemically modified on the surface of the metal nanoparticles contains one or both of a hydroxyl group (—OH) and a carbonyl group (—C═O). The reason why the water content is preferably in the range of 1% by weight or more with respect to 100% by weight of all the dispersion media was obtained by applying the composition by a wet coating method when it was less than 1% by weight. It is difficult to sinter the film at a low temperature, and the conductivity and reflectance of the electrode after firing are lowered, and the content of alcohols is preferably in the range of 2% by weight or more with respect to 100% by weight of all dispersion media. If the amount is less than 2% by weight, it is difficult to sinter the film obtained by applying the composition by the wet coating method in the same manner as described above, and the conductivity and reflection of the electrode after firing are reduced. This is because the rate drops. In addition, when a hydroxyl group (—OH) is contained in a protective agent that chemically modifies metal nanoparticles such as silver nanoparticles, the composition has excellent dispersion stability and has an effective effect on low-temperature sintering of the coating film. Yes, when a carbonyl group (—C═O) is contained in a protective agent that chemically modifies metal nanoparticles such as silver nanoparticles, the composition has excellent dispersion stability as described above, and the coating film is sintered at low temperature. Also has an effective action. As the alcohols used in the dispersion medium, one or more selected from the group consisting of methanol, ethanol, propanol, butanol, ethylene glycol, propylene glycol, diethylene glycol, glycerol, isobornyl hexanol and erythritol may be used. preferable.
本発明の太陽電池の電極の形成方法に用いる電極形成用組成物を製造する方法は以下の通りである。
(a) 銀ナノ粒子を化学修飾する保護剤の有機分子主鎖の炭素骨格の炭素数を３とする場合
先ず硝酸銀を脱イオン水等の水に溶解して金属塩水溶液を調製する。一方、クエン酸ナトリウムを脱イオン水等の水に溶解させて得られた濃度１０〜４０％のクエン酸ナトリウム水溶液に、窒素ガス等の不活性ガスの気流中で粒状又は粉状の硫酸第一鉄を直接加えて溶解させ、クエン酸イオンと第一鉄イオンを３：２のモル比で含有する還元剤水溶液を調製する。次に上記不活性ガス気流中で上記還元剤水溶液を撹拌しながら、この還元剤水溶液に上記金属塩水溶液を滴下して混合する。ここで、金属塩水溶液の添加量は還元剤水溶液の量の１／１０以下になるように、各溶液の濃度を調整することで、室温の金属塩水溶液を滴下しても反応温度が３０〜６０℃に保持されるようにすることが好ましい。また上記両水溶液の混合比は、金属塩水溶液中の金属イオンの総原子価数に対する、還元剤水溶液中のクエン酸イオンと第一鉄イオンのモル比がいずれも３倍モルとなるようにする。金属塩水溶液の滴下が終了した後、混合液の撹拌を更に１０〜３００分間続けて金属コロイドからなる分散液を調製する。この分散液を室温で放置し、沈降した金属ナノ粒子の凝集物をデカンテーションや遠心分離法等により分離した後、この分離物に脱イオン水等の水を加えて分散体とし、限外ろ過により脱塩処理し、更に引き続いてアルコール類で置換洗浄して、金属（銀）の含有量を２．５〜５０重量％にする。その後、遠心分離機を用いこの遠心分離機の遠心力を調整して粗粒子を分離することにより、金属ナノ粒子が一次粒径１０〜５０ｎｍの範囲内の金属ナノ粒子を数平均で７０％以上含有するように調製する、即ち数平均で全ての金属ナノ粒子１００％に対する一次粒径１０〜５０ｎｍの範囲内の金属ナノ粒子の占める割合が７０％以上になるように調整する。なお、金属ナノ粒子と記載したが、この(a)の場合では、数平均で全ての銀ナノ粒子１００％に対する一次粒径１０〜５０ｎｍの範囲内の銀ナノ粒子の占める割合が７０％以上になるように調整している。
The method for producing the electrode forming composition used in the method for forming the electrode of the solar cell of the present invention is as follows.
(a) When the carbon number of the carbon skeleton of the organic molecular main chain of the protective agent for chemically modifying the silver nanoparticles is set to 3 First, silver nitrate is dissolved in water such as deionized water to prepare an aqueous metal salt solution. On the other hand, the aqueous solution of sodium citrate having a concentration of 10 to 40% obtained by dissolving sodium citrate in deionized water or the like is mixed with granular or powdered sulfuric acid in a stream of inert gas such as nitrogen gas. Iron is directly added and dissolved to prepare an aqueous reducing agent solution containing citrate ions and ferrous ions in a molar ratio of 3: 2. Next, the aqueous metal salt solution is added dropwise to and mixed with the reducing agent aqueous solution while stirring the reducing agent aqueous solution in the inert gas stream. Here, by adjusting the concentration of each solution so that the addition amount of the metal salt aqueous solution is 1/10 or less of the amount of the reducing agent aqueous solution, the reaction temperature is 30 to 30 even when the metal salt aqueous solution at room temperature is dropped. It is preferable to keep the temperature at 60 ° C. The mixing ratio of the two aqueous solutions is such that the molar ratio of the citrate ions and the ferrous ions in the reducing agent aqueous solution is 3 times the total valence of the metal ions in the metal salt aqueous solution. . After the dropping of the aqueous metal salt solution is completed, the mixture is further stirred for 10 to 300 minutes to prepare a dispersion composed of metal colloid. This dispersion is allowed to stand at room temperature, and the aggregates of the precipitated metal nanoparticles are separated by decantation, centrifugation, etc., and then water such as deionized water is added to the separation to form a dispersion, followed by ultrafiltration. The metal (silver) content is adjusted to 2.5 to 50% by weight. Thereafter, by adjusting the centrifugal force of the centrifuge using a centrifuge and separating coarse particles, the metal nanoparticles having a primary particle diameter in the range of 10 to 50 nm are 70% or more in average number of metal nanoparticles. It adjusts so that the ratio for which the metal nanoparticle in the range of the primary particle size of 10-50 nm with respect to 100% of all the metal nanoparticles may be 70% or more may be prepared. Although described as metal nanoparticles, in the case of (a), the proportion of silver nanoparticles in the range of the primary particle size of 10 to 50 nm with respect to 100% of all silver nanoparticles is 70% or more. It is adjusted so that
数平均の測定方法は、先ず、得られた金属ナノ粒子をＴＥＭ（Transmission Electron Microscope、透過型電子顕微鏡）により約５０万倍程度の倍率で撮影する。次いで、得られた画像から金属ナノ粒子２００個について一次粒径を測定し、この測定結果をもとに粒径分布を作成する。次に、作成した粒径分布から、一次粒径１０〜５０ｎｍの範囲内の金属ナノ粒子が全金属ナノ粒子で占める個数割合を求める。 In the number average measurement method, first, the obtained metal nanoparticles are photographed with a TEM (Transmission Electron Microscope) at a magnification of about 500,000 times. Next, a primary particle size is measured for 200 metal nanoparticles from the obtained image, and a particle size distribution is created based on the measurement result. Next, from the created particle size distribution, the ratio of the number of metal nanoparticles within the range of the primary particle size of 10 to 50 nm occupied by all metal nanoparticles is determined.
これにより銀ナノ粒子を化学修飾する保護剤の有機分子主鎖の炭素骨格の炭素数が３である分散体（太陽電池の電極形成用組成物）が得られる。なお、この分散体１００重量％に対する最終的な金属含有量（銀含有量）は２．５〜９５重量％とするとともに、溶媒の水及びアルコール類をそれぞれ１％以上及び２％以上にそれぞれ調整する。 As a result, a dispersion (a composition for forming an electrode of a solar cell) in which the carbon skeleton of the carbon skeleton of the organic molecular main chain of the protective agent that chemically modifies the silver nanoparticles is obtained. The final metal content (silver content) with respect to 100% by weight of the dispersion is 2.5 to 95% by weight, and the solvent water and alcohol are adjusted to 1% or more and 2% or more, respectively. To do.
(b) 銀ナノ粒子を化学修飾する保護剤の有機分子主鎖の炭素骨格の炭素数を２とする場合
還元剤水溶液を調製するときに用いたクエン酸ナトリウムをりんご酸ナトリウムに替えること以外は上記(a)と同様にして分散体を調製する。これにより銀ナノ粒子を化学修飾する有機分子主鎖の炭素骨格の炭素数が２である分散体（太陽電池の電極形成用組成物）が得られる。
(b) When the carbon number of the carbon skeleton of the organic molecular main chain of the protective agent that chemically modifies the silver nanoparticles is 2, except that the sodium citrate used when preparing the reducing agent aqueous solution is replaced with sodium malate A dispersion is prepared in the same manner as in the above (a). As a result, a dispersion (a composition for forming an electrode for a solar cell) in which the carbon skeleton of the organic molecular main chain that chemically modifies the silver nanoparticles has 2 carbon atoms is obtained.
(c) 銀ナノ粒子を化学修飾する保護剤の有機分子主鎖の炭素骨格の炭素数を１とする場合
還元剤水溶液を調製するときに用いたクエン酸ナトリウムをグリコール酸ナトリウムに替えること以外は上記(a)と同様にして分散体を調製する。これにより銀ナノ粒子を化学修飾する有機分子主鎖の炭素骨格の炭素数が１である分散体（太陽電池の電極形成用組成物）が得られる。
(c) When the carbon number of the carbon skeleton of the organic molecular main chain of the protective agent for chemically modifying the silver nanoparticles is 1, except that sodium citrate used when preparing the reducing agent aqueous solution is replaced with sodium glycolate A dispersion is prepared in the same manner as in the above (a). Thereby, a dispersion (composition for forming an electrode of a solar cell) in which the carbon skeleton of the organic molecular main chain that chemically modifies the silver nanoparticles has 1 is obtained.
(d) 銀ナノ粒子以外の金属ナノ粒子を化学修飾する保護剤の有機分子主鎖の炭素骨格の炭素数を３とする場合
銀ナノ粒子以外の金属ナノ粒子を構成する金属としては、Ａｕ、Ｐｔ、Ｐｄ、Ｒｕ、Ｎｉ、Ｃｕ、Ｓｎ、Ｉｎ、Ｚｎ、Ｆｅ、Ｃｒ又はＭｎが挙げられる。金属塩水溶液を調製するときに用いた硝酸銀を、塩化金酸、塩化白金酸、硝酸パラジウム、三塩化ルテニウム、塩化ニッケル、硝酸第一銅、二塩化錫、硝酸インジウム、塩化亜鉛、硫酸鉄、硫酸クロム又は硫酸マンガンに替えること以外は上記(a)と同様にして分散体を調製する。これにより銀ナノ粒子以外の金属ナノ粒子を化学修飾する保護剤の有機分子主鎖の炭素骨格の炭素数が３である分散体（太陽電池の電極形成用組成物）が得られる。
(d) When the number of carbon atoms in the carbon skeleton of the organic molecular main chain of the protective agent for chemically modifying metal nanoparticles other than silver nanoparticles is 3, the metal constituting the metal nanoparticles other than silver nanoparticles is Au, Pt, Pd, Ru, Ni, Cu, Sn, In, Zn, Fe, Cr, or Mn may be mentioned. The silver nitrate used to prepare the aqueous metal salt solution is chloroauric acid, chloroplatinic acid, palladium nitrate, ruthenium trichloride, nickel chloride, cuprous nitrate, tin dichloride, indium nitrate, zinc chloride, iron sulfate, sulfuric acid A dispersion is prepared in the same manner as in the above (a) except that it is replaced with chromium or manganese sulfate. As a result, a dispersion (a composition for forming an electrode for a solar cell) in which the carbon skeleton of the organic molecular main chain of the protective agent for chemically modifying metal nanoparticles other than silver nanoparticles is 3 is obtained.
なお、銀ナノ粒子以外の金属ナノ粒子を化学修飾する保護剤の有機分子主鎖の炭素骨格の炭素数を１や２とする場合、金属塩水溶液を調製するときに用いた硝酸銀を、上記種類の金属塩に替えること以外は上記(b)や上記(c)と同様にして分散体を調製する。これにより、銀ナノ粒子以外の金属ナノ粒子を化学修飾する保護剤の有機分子主鎖の炭素骨格の炭素数が１や２である分散体（太陽電池の電極形成用組成物）が得られる。 In addition, when the carbon number of the carbon skeleton of the organic molecular main chain of the protective agent that chemically modifies the metal nanoparticles other than the silver nanoparticles is 1 or 2, the silver nitrate used when preparing the metal salt aqueous solution is the above kind. A dispersion is prepared in the same manner as in the above (b) and (c) except that the metal salt is replaced. Thereby, the dispersion (composition for electrode formation of a solar cell) whose carbon number of the carbon skeleton of the organic molecular principal chain of the protective agent which chemically modifies metal nanoparticles other than silver nanoparticles is 1 or 2 is obtained.
金属ナノ粒子として、銀ナノ粒子とともに、銀ナノ粒子以外の金属ナノ粒子を含有させる場合には、上記(a)の方法で製造した銀ナノ粒子を含む分散体を第１分散体とし、上記(d)の方法で製造した銀ナノ粒子以外の金属ナノ粒子を含む分散体を第２分散体とすると、７５重量％以上の第１分散体と２５重量％未満の第２分散体とを第１及び第２分散体の合計含有量が１００重量％となるように混合する。なお、第１分散体は、上記(a)の方法で製造した銀ナノ粒子を含む分散体に留まらず、上記(b)の方法で製造した銀ナノ粒子を含む分散体や上記(c)の方法で製造した銀ナノ粒子を含む分散体を使用しても良い。 When metal nanoparticles other than silver nanoparticles are contained together with silver nanoparticles as metal nanoparticles, a dispersion containing silver nanoparticles produced by the method of (a) is used as the first dispersion, and ( When the dispersion containing metal nanoparticles other than silver nanoparticles produced by the method of d) is defined as the second dispersion, the first dispersion of 75% by weight or more and the second dispersion of less than 25% by weight are the first. And it mixes so that the total content of a 2nd dispersion may be 100 weight%. The first dispersion is not limited to the dispersion containing the silver nanoparticles produced by the method (a), but the dispersion containing the silver nanoparticles produced by the method (b) or the above (c). You may use the dispersion containing the silver nanoparticle manufactured by the method.
次に、このように製造された分散体（太陽電池の電極形成用組成物）を用いて電極を形成する方法を説明する。
先ず基材表面にプライマー処理を施す。基材へプライマー処理を施す際の塗布物の塗布方法は、スプレーコーティング法、ディスペンサコーティング法、スピンコーティング法、ナイフコーティング法、スリットコーティング法、インクジェットコーティング法、スクリーン印刷法、オフセット印刷法又はダイコーティング法のいずれかであることが特に好ましいが、これに限られるものではなく、あらゆる方法を利用できる。基材上に塗布した塗布物は２０〜１００℃で１０秒間〜３０分間保持して乾燥させる。若しくは２０〜１００℃の送風にて１０秒〜３０分間保持して乾燥させる。好ましくは４０℃の送風にて１５秒間保持して乾燥させる。プライマー処理を施し、その後に電極形成用組成物により電極を形成する基材としては、シリコン、ガラス、透明導電材料を含むセラミックス、高分子材料又は金属からなる基板のいずれか、或いはシリコン、ガラス、透明導電材料を含むセラミックス、高分子材料及び金属からなる群より選ばれた２種以上の積層体であることができる。また透明導電膜のいずれか１種を少なくとも含む基材や、透明導電膜を表面に成膜した基材を用いてもよい。透明導電膜としては、酸化インジウム系、酸化スズ系、酸化亜鉛系が挙げられる。酸化インジウム系としては、酸化インジウム、ＩＴＯ（Indium Tin Oxide：インジウム錫酸化物）、ＩＺＯ（Indium Zic Oxide）が挙げられる。酸化錫系としては、ネサ（酸化錫ＳｎＯ2）、ＡＴＯ（Antimony Tin Oxide：アンチモンドープ酸化錫）、フッ素ドープ酸化錫が挙げられる。酸化亜鉛系としては、酸化亜鉛、ＡＺＯ（アルミドープ酸化亜鉛）、ガリウムドープ酸化亜鉛が挙げられる。基材は太陽電池素子又は透明電極付き太陽電池素子のいずれかであることが好ましい。透明電極としては、ＩＴＯ、ＡＴＯ、ネサ、ＩＺＯ、ＡＺＯ等などが挙げられる。高分子基板としては、ポリイミドやＰＥＴ（ポリエチレンテレフタレート）等の有機ポリマーにより形成された基板が挙げられる。プライマー処理は太陽電池素子の光電変換半導体層の表面や、透明電極付き太陽電池素子の透明電極の表面等に施される。
Next, a method for forming an electrode using the thus-produced dispersion (a composition for forming an electrode for a solar cell) will be described.
First, a primer treatment is applied to the substrate surface. The application method for applying the primer to the substrate is spray coating, dispenser coating, spin coating, knife coating, slit coating, inkjet coating, screen printing, offset printing or die coating. Although any one of the methods is particularly preferable, the present invention is not limited to this, and any method can be used. The coating applied on the substrate is dried by holding at 20 to 100 ° C. for 10 seconds to 30 minutes. Or it is made to dry by hold | maintaining for 10 second-30 minutes by 20-100 degreeC ventilation. Preferably, it is dried by holding at 40 ° C. for 15 seconds. As a base material that is subjected to primer treatment and then forms an electrode with the electrode forming composition, silicon, glass, ceramics including a transparent conductive material, a substrate made of a polymer material or metal, or silicon, glass, It can be a laminate of two or more selected from the group consisting of ceramics including transparent conductive materials, polymer materials, and metals. Moreover, you may use the base material which contains any 1 type of transparent conductive films, and the base material which formed the transparent conductive film on the surface. Examples of the transparent conductive film include indium oxide, tin oxide, and zinc oxide. Examples of indium oxide include indium oxide, ITO (Indium Tin Oxide), and IZO (Indium Zic Oxide). Examples of tin oxide include Nesa (tin oxide SnO 2 ), ATO (Antimony Tin Oxide), and fluorine-doped tin oxide. Examples of the zinc oxide system include zinc oxide, AZO (aluminum doped zinc oxide), and gallium doped zinc oxide. The substrate is preferably either a solar cell element or a solar cell element with a transparent electrode. Examples of the transparent electrode include ITO, ATO, Nesa, IZO, AZO and the like. Examples of the polymer substrate include a substrate formed of an organic polymer such as polyimide or PET (polyethylene terephthalate). The primer treatment is performed on the surface of the photoelectric conversion semiconductor layer of the solar cell element, the surface of the transparent electrode of the solar cell element with a transparent electrode, or the like.
次いで、太陽電池の電極形成用組成物をプライマー処理を施した基材上に湿式塗工法で塗工する。この湿式塗工法での塗工は、焼成後の厚さが０．１〜２．０μｍ、好ましくは０．３〜１．５μｍの範囲内となるように成膜する。湿式塗工法は、スプレーコーティング法、ディスペンサコーティング法、スピンコーティング法、ナイフコーティング法、スリットコーティング法、インクジェットコーティング法、スクリーン印刷法、オフセット印刷法又はダイコーティング法のいずれかであることが特に好ましいが、これに限られるものではなく、あらゆる方法を利用できる。スプレーコーティング法は分散体を圧縮エアにより霧状にして基材に塗布したり、或いは分散体自体を加圧し霧状にして基材に塗布する方法であり、ディスペンサコーティング法は例えば分散体を注射器に入れこの注射器のピストンを押すことにより注射器先端の微細ノズルから分散体を吐出させて基材に塗布する方法である。スピンコーティング法は分散体を回転している基材上に滴下し、この滴下した分散体をその遠心力により基材周縁に拡げる方法であり、ナイフコーティング法はナイフの先端と所定の隙間をあけた基材を水平方向に移動可能に設け、このナイフより上流側の基材上に分散体を供給して基材を下流側に向って水平移動させる方法である。スリットコーティング法は分散体を狭いスリットから流出させて基材上に塗布する方法であり、インクジェットコーティング法は市販のインクジェットプリンタのインクカートリッジに分散体を充填し、基材上にインクジェット印刷する方法である。スクリーン印刷法は、パターン指示材として紗を用い、その上に作られた版画像を通して分散体を基材に転移させる方法である。オフセット印刷法は、版に付けた分散体を直接基材に付着させず、版から一度ゴムシートに転写させ、ゴムシートから改めて基材に転移させる、インクの撥水性を利用した印刷方法である。ダイコーティング法は、ダイ内に供給された分散体をマニホールドで分配させてスリットより薄膜上に押し出し、走行する基材の表面を塗工する方法である。ダイコーティング法には、スロットコート方式やスライドコート方式、カーテンコート方式がある。 Next, the electrode-forming composition of the solar cell is applied onto the substrate subjected to the primer treatment by a wet coating method. Coating by this wet coating method is performed so that the thickness after firing is in the range of 0.1 to 2.0 μm, preferably 0.3 to 1.5 μm. The wet coating method is particularly preferably a spray coating method, a dispenser coating method, a spin coating method, a knife coating method, a slit coating method, an inkjet coating method, a screen printing method, an offset printing method or a die coating method. However, the present invention is not limited to this, and any method can be used. The spray coating method is a method in which the dispersion is atomized by compressed air and applied to the substrate, or the dispersion itself is pressurized and atomized to apply to the substrate. The dispenser coating method is, for example, a method in which the dispersion is injected into a syringe. The dispersion is discharged from the fine nozzle at the tip of the syringe and applied to the substrate by pushing the piston of the syringe. The spin coating method is a method in which a dispersion is dropped onto a rotating substrate, and the dropped dispersion is spread to the periphery of the substrate by its centrifugal force. The knife coating method leaves a predetermined gap from the tip of the knife. In this method, the substrate is provided so as to be movable in the horizontal direction, the dispersion is supplied onto the substrate upstream of the knife, and the substrate is moved horizontally toward the downstream side. The slit coating method is a method in which a dispersion is discharged from a narrow slit and applied onto a substrate, and the inkjet coating method is a method in which a dispersion is filled in an ink cartridge of a commercially available inkjet printer and ink jet printing is performed on the substrate. is there. The screen printing method is a method in which wrinkles are used as a pattern indicating material and a dispersion is transferred to a substrate through a plate image formed thereon. The offset printing method is a printing method utilizing the water repellency of ink, in which the dispersion attached to the plate is not directly attached to the substrate, but is transferred from the plate to a rubber sheet and then transferred from the rubber sheet to the substrate again. . The die coating method is a method in which a dispersion supplied in a die is distributed by a manifold and extruded onto a thin film from a slit to coat the surface of a traveling substrate. The die coating method includes a slot coat method, a slide coat method, and a curtain coat method.
次に上面に成膜された基材を大気中で１３０〜４００℃、好ましくは１４０〜３００℃の温度に、１０分間〜１時間、好ましくは１５〜４０分間保持して焼成する。ここで、基材上に形成された分散体の膜厚を０．１〜２．０μｍの範囲に限定したのは、０．１μｍ未満では太陽電池に必要な電極の表面抵抗値が不十分となり、２．０μｍを越えると特性上の不具合はないけれども、材料の使用量が必要以上に多くなって材料が無駄になるからである。また基材上に形成された分散体の膜の焼成温度を１３０〜４００℃の範囲に限定したのは、１３０℃未満では金属ナノ粒子同士の焼結が不十分になるとともに保護剤の焼成時の熱により脱離或いは分解（分離・燃焼）し難いため、焼成後の電極内に有機残渣が多く残り、この残渣が変質又は劣化して導電性及び反射率が低下してしまい、４００℃を越えると低温プロセスという生産上のメリットを生かせない、即ち製造コストが増大し生産性が低下してしまうからである。更に基材上に形成された分散体の膜の焼成時間を１０分間〜１時間の範囲に限定したのは、１０分間未満では金属ナノ粒子同士の焼結が不十分になるとともに保護剤の焼成時の熱により脱離或いは分解（分離・燃焼）し難いため、焼成後の電極内に有機残渣が多く残り、この残渣が変質又は劣化して電極の導電性及び反射率が低下してしまい、１時間を越えると特性には影響しないけれども、必要以上に製造コストが増大して生産性が低下してしまうからである。 Next, the base material formed on the upper surface is fired in the atmosphere at a temperature of 130 to 400 ° C., preferably 140 to 300 ° C., for 10 minutes to 1 hour, preferably 15 to 40 minutes. Here, the film thickness of the dispersion formed on the substrate is limited to the range of 0.1 to 2.0 μm because the surface resistance value of the electrode necessary for the solar cell is insufficient when the thickness is less than 0.1 μm. If the thickness exceeds 2.0 μm, there is no problem in characteristics, but the amount of the material used is more than necessary and the material is wasted. In addition, the firing temperature of the dispersion film formed on the base material was limited to the range of 130 to 400 ° C. When the temperature was lower than 130 ° C., the sintering between the metal nanoparticles became insufficient and the protective agent was fired. It is difficult to desorb or decompose (separate / combust) due to the heat of heat, so that a lot of organic residue remains in the electrode after firing, and this residue is altered or deteriorated, resulting in a decrease in conductivity and reflectance. This is because the production advantage of the low-temperature process cannot be utilized, that is, the manufacturing cost increases and the productivity decreases. Furthermore, the firing time of the dispersion film formed on the base material was limited to the range of 10 minutes to 1 hour because the sintering of the metal nanoparticles became insufficient and the firing of the protective agent in less than 10 minutes. Due to the difficulty of desorption or decomposition (separation / combustion) due to the heat of the time, a lot of organic residue remains in the electrode after firing, the residue is altered or deteriorated, and the conductivity and reflectivity of the electrode decrease, This is because, if the time exceeds 1 hour, the characteristics are not affected, but the manufacturing cost is increased more than necessary and the productivity is lowered.
上記太陽電池の電極形成用組成物では、一次粒径１０〜５０ｎｍとサイズの比較的大きい金属ナノ粒子を多く含むため、金属ナノ粒子の比表面積が減少し、保護剤の占める割合が小さくなる。この結果、上記組成物を用いて太陽電池の電極を形成すると、上記保護剤中の有機分子が焼成時の熱により脱離し又は分解し、或いは離脱しかつ分解することにより、実質的に有機物を含有しない銀を主成分とする電極が得られる。従って、上記電極の形成された太陽電池を長年使用しても、有機物が変質又は劣化するということがなく、電極の導電率及び反射率が高い状態に維持されるので、経年安定性に優れた電極を得ることができる。具体的には、上記電極を、温度を１００℃に保ちかつ湿度を５０％に保った恒温恒湿槽に１０００時間収容した後であっても、波長７５０〜１５００ｎｍの電磁波、即ち可視光領域から赤外線領域までの電磁波を８０％以上電極により反射できるとともに、電極の導電性、即ち電極の体積抵抗率を２×１０-5Ω・ｃｍ（２０×１０-6Ω・ｃｍ）未満と極めて低い値に維持できる。このようにして形成された電極を用いた太陽電池は、長年使用しても高導電率及び高反射率を維持することができ、経年安定性に優れる。 Since the composition for forming an electrode of the solar cell contains a large amount of metal nanoparticles having a primary particle size of 10 to 50 nm and a relatively large size, the specific surface area of the metal nanoparticles is reduced and the proportion of the protective agent is reduced. As a result, when an electrode of a solar cell is formed using the composition, the organic molecules in the protective agent are desorbed or decomposed by the heat at the time of firing, or desorbed and decomposed, thereby substantially reducing the organic matter. An electrode composed mainly of silver not containing is obtained. Therefore, even if the solar cell on which the electrode is formed is used for many years, the organic matter is not deteriorated or deteriorated, and the conductivity and reflectivity of the electrode are maintained in a high state, so that the aging stability is excellent. An electrode can be obtained. Specifically, even after the electrode is accommodated for 1000 hours in a constant temperature and humidity chamber maintained at a temperature of 100 ° C. and a humidity of 50%, the electromagnetic wave having a wavelength of 750 to 1500 nm, that is, from the visible light region. Electromagnetic waves up to the infrared region can be reflected by 80% or more by the electrode, and the conductivity of the electrode, that is, the volume resistivity of the electrode is extremely low, less than 2 × 10 −5 Ω · cm (20 × 10 −6 Ω · cm). Can be maintained. The solar cell using the electrode formed in this way can maintain high conductivity and high reflectance even when used for many years, and is excellent in aging stability.
次に本発明の実施例を比較例とともに詳しく説明する。
＜実施例１〜４＞
次の表１に示す平均粒径が約２０ｎｍの金属ナノ粒子１０重量部を水、エタノール及びメタノールの混合溶液に分散させた電極形成用組成物を用意した。なお、実施例１〜４で使用する電極形成用組成物は、銀ナノ粒子のみを使用する場合、金属ナノ粒子中の銀ナノ粒子の含有率は１００％であり、銀ナノ粒子と銀以外の金属ナノ粒子の両方を使用している場合、金属ナノ粒子中の銀ナノ粒子の含有率は９５％である。また、金属ナノ粒子を化学修飾する有機分子の炭素骨格は炭素数３であり、金属ナノ粒子に含まれる一次粒径１０〜５０ｎｍの範囲内の金属ナノ粒子の数平均は８０％である。また表１に示す含有材料１重量部を水、エタノール及びメタノールの混合溶液に分散させたプライマー塗布物を用意した。また表１に示す基材を用意した。
Next, examples of the present invention will be described in detail together with comparative examples.
<Examples 1 to 4 >
An electrode-forming composition was prepared by dispersing 10 parts by weight of metal nanoparticles having an average particle size of about 20 nm shown in Table 1 below in a mixed solution of water, ethanol and methanol. In addition, when the composition for electrode formation used in Examples 1-4 uses only silver nanoparticles, the content rate of silver nanoparticles in metal nanoparticles is 100%, and other than silver nanoparticles and silver When both metal nanoparticles are used, the content of silver nanoparticles in the metal nanoparticles is 95%. The carbon skeleton of the organic molecule that chemically modifies the metal nanoparticles has 3 carbon atoms, and the number average of the metal nanoparticles in the primary particle size range of 10 to 50 nm contained in the metal nanoparticles is 80%. Moreover, the primer coating material which disperse | distributed 1 weight part of containing materials shown in Table 1 to the mixed solution of water, ethanol, and methanol was prepared. Moreover , the base material shown in Table 1 was prepared.
次に、基材上にプライマー塗布物を次の表１に示す塗布方法により塗布し、大気中で６０℃、３０分間乾燥させた。続いてこのプライマー塗布物の塗布を行った基材上に電極形成用組成物を焼成後の厚さが３００ｎｍとなるように次の表１に示す塗布方法により成膜した後に、表１に示す温度で３０分間焼成することにより、基材上に電極を形成した。なお、次の表１中に示されるスプレーＣはスプレーコーティングを、ディスペンサＣはディスペンサコーティングを、インクジェットＣはインクジェットコーティングを、スピンＣはスピンコーティングを、ダイＣはダイコーティングをそれぞれ示す。 Next, the primer coating was applied onto the substrate by the coating method shown in the following Table 1, and dried in the atmosphere at 60 ° C. for 30 minutes. Then, after forming into a film by the application | coating method shown in following Table 1 so that the thickness after baking the composition for electrode formation on the base material which apply | coated this primer coating material might be set to 300 nm, it shows in Table 1. An electrode was formed on the substrate by baking at a temperature for 30 minutes. Incidentally, the spray C spray coating shown next in Table 1, the dispenser C is a dispenser coating, inkjet C inkjet coating, spin C spin coating, die C represents, respectively Re its die coating.
＜比較例１〜５＞
次の表１に示す平均粒径が約２０ｎｍの金属ナノ粒子１０重量部を水、エタノール及びメタノールの混合溶液に分散させた電極形成用組成物を用意した。なお、比較例１〜５で使用する電極形成用組成物は、金属ナノ粒子中の銀ナノ粒子の含有率は１００％である。また、金属ナノ粒子を化学修飾する有機分子の炭素骨格は炭素数３であり、金属ナノ粒子に含まれる一次粒径１０〜５０ｎｍの範囲内の金属ナノ粒子の数平均は８０％である。また表１に示す基材を用意した。
次に、基材に対してプライマー処理することなく、電極形成用組成物を基材上に３００ｎｍの膜厚となるように次の表１に示す塗布方法により成膜した後に、表１に示す温度で３０分間焼成することにより、基材上に電極を形成した。
<Comparative Examples 1-5>
An electrode-forming composition was prepared by dispersing 10 parts by weight of metal nanoparticles having an average particle size of about 20 nm shown in Table 1 below in a mixed solution of water, ethanol and methanol. In addition, as for the composition for electrode formation used in Comparative Examples 1-5, the content rate of the silver nanoparticle in a metal nanoparticle is 100%. The carbon skeleton of the organic molecule that chemically modifies the metal nanoparticles has 3 carbon atoms, and the number average of the metal nanoparticles in the primary particle size range of 10 to 50 nm contained in the metal nanoparticles is 80%. Moreover, the base material shown in Table 1 was prepared.
Next, the electrode forming composition is formed on the substrate by the coating method shown in the following Table 1 so as to have a film thickness of 300 nm without performing primer treatment on the substrate, and then shown in Table 1 . An electrode was formed on the substrate by baking at a temperature for 30 minutes.
＜比較試験１＞
実施例１〜４及び比較例１〜５で得られた電極を形成した基材について、導電性及び基材への接着性を評価した。導電性は、四端子法により測定し算出した体積抵抗率（Ω・ｃｍ）として求めた。具体的には、電極の体積抵抗率は、先ず焼成後の電極の厚さをＳＥＭ（日立製作所社製の電子顕微鏡：Ｓ８００）を用いて電極断面から電極の厚さを直接計測し、次に四端子法による比抵抗測定器（三菱化学製ロレスタＧＰ）を用い、この測定器に上記実測した電極の厚さを入力して測定した。基材への密着性は、電極を形成した基材への接着テープ引き剥がし試験により定性的に評価し、『良好』とは、基材から接着テープのみが剥がれた場合を示し、『中立』とは、接着テープの剥がれと基材表面が露出した状態が混在した場合を示し、『不良』とは、接着テープ引き剥がしによって基材表面の全面が露出した場合を示す。その結果を表２に示す。
<Comparison test 1>
About the base material in which the electrode obtained in Examples 1-4 and Comparative Examples 1-5 was formed, electroconductivity and the adhesiveness to a base material were evaluated. The conductivity was determined as a volume resistivity (Ω · cm) measured and calculated by the four probe method. Specifically, the volume resistivity of the electrode is obtained by first measuring the thickness of the electrode after firing directly from the electrode cross section using an SEM (Hitachi Ltd. electron microscope: S800), Using a specific resistance measuring device (Loresta GP, manufactured by Mitsubishi Chemical Corporation) by a four-terminal method, the measured thickness of the electrode was input and measured. Adhesion to the substrate is qualitatively evaluated by an adhesive tape peeling test on the substrate on which the electrode is formed. “Good” indicates that only the adhesive tape is peeled off from the substrate. The case where the peeling of the adhesive tape and the state where the surface of the base material is exposed coexists, and the term “defect” indicates the case where the entire surface of the base material is exposed due to the peeling of the adhesive tape. The results are shown in Table 2 .
表２から明らかなように、プライマー処理を施していない比較例１〜５では、導電率は１０-6オーダーの数値を示したが、接着性評価はいずれも例も『不良』を示し、形成した電極が接着テープによって剥がれてしまい、基材表面が露出してしまっていた。一方、実施例１〜４では、優れた導電性を有しており、また接着性評価も、『良好』か『中立』を示しており、プライマー処理を施すことで、導電性を損なうことなく、基材との密着性を向上させることができることが確認された。 As is apparent from Table 2, in Comparative Examples 1 to 5 where the primer treatment was not performed, the electrical conductivity showed a numerical value of the order of 10 −6 , but the adhesiveness evaluations showed “bad” in all cases, and the formation was The peeled electrode was peeled off by the adhesive tape, and the base material surface was exposed. On the other hand, in Examples 1 to 4 , it has excellent conductivity, and the adhesion evaluation also shows “good” or “neutral”, and by applying the primer treatment, the conductivity is not impaired. It was confirmed that the adhesion to the substrate can be improved .
Claims (9)
前記基材にＡｇの金属酸化物を含む塗布物を塗布してプライマー処理を施すことを特徴とする太陽電池の電極の形成方法。 In a method of forming an electrode of a solar cell, comprising a step of applying a composition for forming an electrode on a substrate by a wet coating method to form a film, and a step of firing the substrate formed on the upper surface.
A method for forming an electrode of a solar cell, comprising applying a coating containing an Ag metal oxide to the substrate and applying a primer treatment.
前記金属ナノ粒子が７５重量％以上の銀ナノ粒子を含有し、
前記金属ナノ粒子は炭素骨格が炭素数１〜３である有機分子主鎖の保護剤で化学修飾され、
前記金属ナノ粒子が一次粒径１０〜５０ｎｍの範囲内の金属ナノ粒子を数平均で７０％以上含有する請求項１記載の太陽電池の電極の形成方法。 The electrode forming composition is a composition in which metal nanoparticles are dispersed in a dispersion medium,
The metal nanoparticles contain 75% by weight or more of silver nanoparticles,
The metal nanoparticles are chemically modified with a protective agent for an organic molecular main chain having a carbon skeleton of 1 to 3 carbon atoms,
The method for forming an electrode of a solar cell according to claim 1, wherein the metal nanoparticles contain 70% or more of metal nanoparticles having a primary particle size in the range of 10 to 50 nm in number average.
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Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6454768A (en) * | 1987-08-26 | 1989-03-02 | Fuji Electric Co Ltd | Manufacture of thin film solar cell |
| JPH06196728A (en) * | 1992-12-25 | 1994-07-15 | Sanyo Electric Co Ltd | Photovoltaic element, and manufacture thereof |
| JPH07106617A (en) * | 1993-09-30 | 1995-04-21 | Canon Inc | Transparent electrode, formation thereof and solar cell employing same |
| JP2000090737A (en) * | 1998-09-16 | 2000-03-31 | Mitsubishi Materials Corp | Conductive membrane and coating liquid for forming conductive membrane |
| JP2001325831A (en) * | 2000-05-12 | 2001-11-22 | Bando Chem Ind Ltd | Metal colloid solution, conductive ink, conductive coating and conductive coating forming base film |
| JP2004143325A (en) * | 2002-10-25 | 2004-05-20 | Bando Chem Ind Ltd | Electroconductive ink |
| JP2005191107A (en) * | 2003-12-24 | 2005-07-14 | Kyocera Corp | Manufacturing method for solar cell device |
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Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6454768A (en) * | 1987-08-26 | 1989-03-02 | Fuji Electric Co Ltd | Manufacture of thin film solar cell |
| JPH06196728A (en) * | 1992-12-25 | 1994-07-15 | Sanyo Electric Co Ltd | Photovoltaic element, and manufacture thereof |
| JPH07106617A (en) * | 1993-09-30 | 1995-04-21 | Canon Inc | Transparent electrode, formation thereof and solar cell employing same |
| JP2000090737A (en) * | 1998-09-16 | 2000-03-31 | Mitsubishi Materials Corp | Conductive membrane and coating liquid for forming conductive membrane |
| JP2001325831A (en) * | 2000-05-12 | 2001-11-22 | Bando Chem Ind Ltd | Metal colloid solution, conductive ink, conductive coating and conductive coating forming base film |
| JP2004143325A (en) * | 2002-10-25 | 2004-05-20 | Bando Chem Ind Ltd | Electroconductive ink |
| JP2005191107A (en) * | 2003-12-24 | 2005-07-14 | Kyocera Corp | Manufacturing method for solar cell device |
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