JP2013018666A - Electrode formation glass and electrode formation material - Google Patents

Electrode formation glass and electrode formation material Download PDF

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JP2013018666A
JP2013018666A JP2011151514A JP2011151514A JP2013018666A JP 2013018666 A JP2013018666 A JP 2013018666A JP 2011151514 A JP2011151514 A JP 2011151514A JP 2011151514 A JP2011151514 A JP 2011151514A JP 2013018666 A JP2013018666 A JP 2013018666A
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glass
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Kentaro Ishihara
健太郎 石原
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Nippon Electric Glass Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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Abstract

PROBLEM TO BE SOLVED: To provide an electrode formation glass which is excellent in anti-deterioration property of an electrode in hot water, excellent in prevention of generation of blisters and an aggregation of Al and further can form Al-Si alloy layer and Al dope layer suitably.SOLUTION: The electrode formation glass includes, as glass composition in mol%, 1-30% BiO, 10-66% BO, and 0.1-25% CaO.

Description

本発明は、電極形成用ガラス及び電極形成材料に関し、特にシリコン太陽電池（単結晶シリコン太陽電池、多結晶シリコン太陽電池、微結晶シリコン太陽電池等を含む）の裏面電極の形成に好適な電極形成用ガラス及び電極形成材料に関する。   The present invention relates to an electrode forming glass and an electrode forming material, and particularly suitable for forming a back electrode of a silicon solar cell (including a single crystal silicon solar cell, a polycrystalline silicon solar cell, a microcrystalline silicon solar cell, etc.). The present invention relates to glass and electrode forming materials.

シリコン太陽電池は、シリコン半導体基板、受光面電極、裏面電極、反射防止膜等を備えており、シリコン半導体基板の受光面側に、グリッド状の受光面電極が形成されると共に、シリコン半導体基板の裏面側に、裏面電極が形成される。また、受光面電極は、Ａｇ電極等が一般的であり、裏面電極は、Ａｌ電極等が一般的である。   The silicon solar cell includes a silicon semiconductor substrate, a light receiving surface electrode, a back electrode, an antireflection film, and the like. A grid-shaped light receiving surface electrode is formed on the light receiving surface side of the silicon semiconductor substrate, and the silicon semiconductor substrate A back electrode is formed on the back side. The light receiving surface electrode is generally an Ag electrode and the back surface electrode is generally an Al electrode.

裏面電極は、通常、厚膜法で形成される。厚膜法は、所望の電極パターンになるように、シリコン半導体基板に電極形成材料をスクリーン印刷し、これを最高温度６６０〜９００℃で短時間焼成（具体的には、焼成開始から終了まで２〜３分、最高温度で２〜１０秒保持）して、Ａｌをシリコン半導体基板に拡散させることにより、シリコン半導体基板に裏面電極を形成する方法である。   The back electrode is usually formed by a thick film method. In the thick film method, an electrode forming material is screen-printed on a silicon semiconductor substrate so as to obtain a desired electrode pattern, and this is fired for a short time at a maximum temperature of 660 to 900 ° C. This is a method of forming a back electrode on a silicon semiconductor substrate by diffusing Al into the silicon semiconductor substrate for 3 minutes and holding at the maximum temperature for 2 to 10 seconds).

裏面電極の形成に用いる電極形成材料は、Ａｌ粉末と、ガラス粉末と、ビークル等を含有する。この電極形成材料を焼成すると、Ａｌ粉末がシリコン半導体基板のＳｉと反応し、裏面電極とシリコン半導体基板の界面にＡｌ−Ｓｉ合金層が形成されると共に、Ａｌ−Ｓｉ合金層とシリコン半導体基板の界面にＡｌドープ層（Ｂａｃｋ Ｓｕｒｆａｃｅ Ｆｉｅｌｄ層、ＢＳＦ層とも称される）が形成される。Ａｌドープ層を形成すれば、電子の再結合を防止し、生成キャリアの収集効率を向上させる効果、所謂ＢＳＦ効果を享受することができる。結果として、Ａｌドープ層を形成すれば、シリコン太陽電池の光電変換効率を高めることができる。   The electrode forming material used for forming the back electrode contains Al powder, glass powder, vehicle and the like. When this electrode forming material is fired, the Al powder reacts with Si of the silicon semiconductor substrate to form an Al—Si alloy layer at the interface between the back electrode and the silicon semiconductor substrate, and between the Al—Si alloy layer and the silicon semiconductor substrate. An Al doped layer (also referred to as a back surface field layer or a BSF layer) is formed at the interface. By forming the Al-doped layer, it is possible to enjoy the effect of preventing recombination of electrons and improving the collection efficiency of generated carriers, the so-called BSF effect. As a result, if an Al-doped layer is formed, the photoelectric conversion efficiency of the silicon solar cell can be increased.

特開２０００−９０７３３号公報JP 2000-90733 A 特開２００３−１６５７４４号公報JP 2003-165744 A

電極形成材料に含まれるガラス粉末は、Ａｌ粉末を結合させて、電極を形成する成分であると共に、Ａｌ粉末とＳｉの反応に影響を及ぼすことにより、Ａｌ−Ｓｉ合金層とＡｌドープ層の形成に関与する成分である（特許文献１、２参照）。   The glass powder contained in the electrode forming material is a component that binds Al powder to form an electrode and affects the reaction between Al powder and Si, thereby forming an Al-Si alloy layer and an Al doped layer. (See Patent Documents 1 and 2).

ところで、従来、電極形成用ガラスとして、鉛ホウ酸系ガラスが使用されてきた。しかし、鉛ホウ酸系ガラスの使用は、環境的観点から、制限される傾向にある。このため、鉛ホウ酸系ガラスを無鉛化する動きが加速している。現時点では、ビスマス系ガラスが、鉛ホウ酸系ガラスの代替材料として有望である。   By the way, lead borate glass has been conventionally used as an electrode forming glass. However, the use of lead borate glass tends to be limited from an environmental point of view. For this reason, the movement to lead-free lead borate glass is accelerating. At present, bismuth glass is promising as an alternative material for lead borate glass.

しかし、従来のビスマス系ガラスは、Ａｌ−Ｓｉ合金層やＡｌドープ層の厚みを適正化することが困難であるため、シリコン太陽電池の光電変換効率を高め難い性質を有していた。具体的には、シリコン半導体基板に形成されるＡｌドープ層が浅いと、ＢＳＦ効果を十分に享受できず、その一方で、Ａｌドープ層がシリコン半導体基板中のｐ型半導体とｎ型半導体の界面まで過剰に深く形成されると、空乏層が悪影響を受けて、ＢＳＦ効果を十分に享受できなくなる。また、従来のビスマス系ガラスは、ブリスターやＡｌの凝集が発生し易くなって、外観不良が発生し易くなるという課題も有している。   However, the conventional bismuth-based glass has a property that it is difficult to increase the photoelectric conversion efficiency of the silicon solar cell because it is difficult to optimize the thickness of the Al—Si alloy layer or the Al-doped layer. Specifically, if the Al doped layer formed on the silicon semiconductor substrate is shallow, the BSF effect cannot be fully enjoyed. On the other hand, the Al doped layer is an interface between the p-type semiconductor and the n-type semiconductor in the silicon semiconductor substrate. If the depth is excessively deep, the depletion layer is adversely affected and the BSF effect cannot be fully enjoyed. Further, the conventional bismuth-based glass has a problem that blisters and Al are easily aggregated and appearance defects are likely to occur.

更に、シリコン太陽電池を長期間使用すると、ＥＶＡ等の樹脂が劣化して、セル内にＨ２Ｏが入り込む事態が想定される。この状態でシリコン太陽電池を長期間使用すると、セル内のＨ２Ｏが高温に加熱される。従来のビスマス系ガラスを用いると、この熱水により電極が劣化するという問題がある。 Furthermore, when a silicon solar battery is used for a long period of time, it is assumed that a resin such as EVA deteriorates and H 2 O enters the cell. When a silicon solar battery is used for a long time in this state, H 2 O in the cell is heated to a high temperature. When conventional bismuth glass is used, there is a problem that the electrode is deteriorated by the hot water.

そこで、本発明は、Ａｌ−Ｓｉ合金層とＡｌドープ層を適正に形成し得ると共に、ブリスターやＡｌの凝集を発生させ難く、しかも熱水による電極の耐劣化性が良好な電極形成用ガラスを創案することを技術的課題とする。   Therefore, the present invention provides an electrode-forming glass that can appropriately form an Al-Si alloy layer and an Al-doped layer, is less likely to cause blistering and Al agglomeration, and has good resistance to deterioration of electrodes by hot water. Creating a technical idea is a technical issue.

本発明者は、鋭意努力の結果、ビスマス系ガラスのガラス組成を所定範囲に規制することにより、上記技術的課題を解決できることを見出し、本発明として、提案するものである。すなわち、本発明の電極形成用ガラスは、ガラス組成として、モル％で、Ｂｉ２Ｏ３ １〜３０％、Ｂ２Ｏ３ １０〜６６％、ＣａＯ ０．１〜２５％を含有することを特徴とする。 As a result of diligent efforts, the present inventor has found that the above technical problem can be solved by regulating the glass composition of bismuth-based glass within a predetermined range, and proposes the present invention. That is, the glass for electrode formation of the present invention is characterized by containing, as a glass composition, mol%, Bi 2 O 3 1-30%, B 2 O 3 10-66%, CaO 0.1-25%. And

上記のようにガラス組成範囲を規制すれば、Ａｌ−Ｓｉ合金層やＡｌドープ層を適正に形成し得ると共に、ブリスターやＡｌの凝集が発生し難くなり、しかも熱水による電極の耐劣化性が向上する。特に、Ｂｉ２Ｏ３の含有量を低下させた上で、ＣａＯを所定量添加すれば、熱水による電極の耐劣化性が顕著に向上する。 If the glass composition range is regulated as described above, an Al-Si alloy layer and an Al-doped layer can be properly formed, and blister and Al agglomeration are unlikely to occur, and the electrode is resistant to deterioration by hot water. improves. In particular, if a predetermined amount of CaO is added after reducing the content of Bi 2 O 3 , the resistance to deterioration of the electrode by hot water is significantly improved.

第二に、本発明の電極形成用ガラスは、更に、Ｌｉ２Ｏ＋Ｎａ２Ｏを０．１〜１５モル％含有することが好ましい。ここで、「Ｌｉ２Ｏ＋Ｎａ２Ｏ」は、Ｌｉ２ＯとＮａ２Ｏの合量を指す。このようにすれば、ガラス本来の耐水性が低下し難くなる。 Secondly, the electrode forming glass of the present invention preferably further contains Li 2 O + Na 2 O 0.1~15 mol%. Here, “Li 2 O + Na 2 O” refers to the total amount of Li 2 O and Na 2 O. If it does in this way, it will become difficult to reduce the original water resistance of glass.

第三に、本発明の電極形成用ガラスは、更に、ＳｉＯ２＋Ａｌ２Ｏ３の含有量を０．１〜２０モル％含有することが好ましい。「ＳｉＯ２＋Ａｌ２Ｏ３」は、ＳｉＯ２とＡｌ２Ｏ３の合量を指す。このようにすれば、熱的安定性を高めることができる。 Thirdly, electrode forming glass of the present invention preferably further contains a content of SiO 2 + Al 2 O 3 0.1~20 mol%. “SiO 2 + Al 2 O 3 ” refers to the total amount of SiO 2 and Al 2 O 3 . In this way, thermal stability can be improved.

第四に、本発明の電極形成用ガラスは、更に、ＣｕＯを０．１〜１５モル％含有することが好ましい。このようにすれば、熱的安定性を高めることができる。   Fourthly, it is preferable that the glass for electrode formation of this invention contains 0.1-15 mol% of CuO further. In this way, thermal stability can be improved.

第五に、本発明の電極形成用ガラスは、実質的にＰｂＯを含有しないことが好ましい。このようにすれば、近年の環境的要請を満たすことができる。ここで、「実質的にＰｂＯを含有しない」は、ガラス組成中のＰｂＯの含有量が１０００ｐｐｍ（質量）未満の場合を指す。   Fifth, it is preferable that the electrode forming glass of the present invention does not substantially contain PbO. In this way, environmental demands in recent years can be satisfied. Here, “substantially does not contain PbO” refers to a case where the content of PbO in the glass composition is less than 1000 ppm (mass).

第六に、本発明の電極形成用ガラスは、シリコン太陽電池の裏面電極の形成に用いることが好ましい。   Sixth, the electrode forming glass of the present invention is preferably used for forming the back electrode of the silicon solar cell.

第七に、本発明の電極形成材料は、上記の電極形成用ガラスからなるガラス粉末と、金属粉末と、ビークルとを含むことを特徴とする。このようにすれば、厚膜法で電極パターンを形成できるため、シリコン太陽電池の生産効率を高めることができる。ここで、「ビークル」は、一般的に、有機溶媒中に樹脂を溶解させたものを指すが、本発明では、樹脂を含有せず、高粘性の有機溶媒（例えば、イソトリデシルアルコール等の高級アルコール）のみで構成される態様を含む。   Seventhly, the electrode forming material of the present invention is characterized by including glass powder made of the above-mentioned electrode forming glass, metal powder, and a vehicle. In this way, since the electrode pattern can be formed by the thick film method, the production efficiency of the silicon solar cell can be increased. Here, “vehicle” generally refers to a resin dissolved in an organic solvent. However, in the present invention, the resin does not contain a high-viscosity organic solvent (for example, isotridecyl alcohol or the like). The aspect comprised only with a higher alcohol) is included.

第八に、本発明の電極形成材料は、ガラス粉末の含有量が０．２〜１０質量％であることが好ましい。このようにすれば、電極の機械的強度を確保した上で、Ａｌ粉末とＳｉの反応を適正化し易くなる。   Eighth, the electrode forming material of the present invention preferably has a glass powder content of 0.2 to 10% by mass. If it does in this way, it will become easy to optimize reaction of Al powder and Si, while ensuring the mechanical strength of an electrode.

第九に、本発明の電極形成材料は、平均粒子径Ｄ５０が３μｍ未満であることが好ましい。ここで、「平均粒子径Ｄ５０」は、レーザー回折法で測定した値を指し、レーザー回折法により測定した際の体積基準の累積粒度分布曲線において、その積算量が粒子の小さい方から累積して５０％である粒子径を表す。 Ninth, the electrode forming material of the present invention preferably has an average particle diameter D 50 is less than 3 [mu] m. Here, the “average particle diameter D 50 ” refers to a value measured by the laser diffraction method. In the volume-based cumulative particle size distribution curve measured by the laser diffraction method, the accumulated amount is accumulated from the smaller particle. The particle diameter is 50%.

第十に、本発明の電極形成材料は、金属粉末として、Ａｌ及びこれらの合金を含むことが好ましい。Ａｌ及びこれらの合金は、導電性が良好であると共に、上記のガラス粉末との適合性が良好である。このため、Ａｌ及びこれらの合金を用いると、焼成時にガラス中に失透や発泡が生じ難くなる。   Tenth, the electrode forming material of the present invention preferably contains Al and an alloy thereof as a metal powder. Al and these alloys have good conductivity and good compatibility with the above glass powder. For this reason, when Al and these alloys are used, devitrification and foaming hardly occur in the glass during firing.

マクロ型ＤＴＡ装置で測定したときの軟化点Ｔｓを示す模式図である。It is a schematic diagram which shows the softening point Ts when it measures with a macro type | mold DTA apparatus.

上記のように各成分の含有範囲を規制した理由を以下に説明する。なお、各成分の含有範囲の説明において、％表示は、特段の断りがない限り、モル％を指す。   The reason why the content range of each component is regulated as described above will be described below. In addition, in description of the containing range of each component,% display points out mol% unless there is particular notice.

Ｂｉ２Ｏ３は、軟化点を調整し得る成分であり、その含有量は１〜３０％、好ましくは３〜２５％、より好ましくは５〜２０％である。Ｂｉ２Ｏ３の含有量が少な過ぎると、軟化点が高くなり過ぎて、焼成時にガラスが溶け難くなるため、Ａｌ粉末とＳｉの反応が過剰になり、結果として、Ａｌ−Ｓｉ合金層とＡｌドープ層が過剰に形成されて、シリコン太陽電池の光電変換効率が低下し易くなる。一方、Ｂｉ２Ｏ３の含有量が多過ぎると、軟化点が低くなり過ぎて、Ａｌ−Ｓｉ合金層とＡｌドープ層が形成され難くなり、ＢＳＦ効果を享受し難くなる。 Bi 2 O 3 is a component capable of adjusting the softening point, and its content is 1 to 30%, preferably 3 to 25%, more preferably 5 to 20%. If the content of Bi 2 O 3 is too small, the softening point becomes too high and the glass becomes difficult to melt during firing, so that the reaction between the Al powder and Si becomes excessive. As a result, the Al—Si alloy layer and the Al Doped layers are formed excessively, and the photoelectric conversion efficiency of the silicon solar cell is likely to be lowered. On the other hand, when the content of Bi 2 O 3 is too large, the softening point becomes too low, and it becomes difficult to form the Al—Si alloy layer and the Al doped layer, and it is difficult to enjoy the BSF effect.

Ｂ２Ｏ３は、ガラスの骨格を形成する成分であり、その含有量は１０〜６６％、好ましくは３５〜６０％、更に好ましくは４０〜５８％、特に好ましくは４５〜５５％である。Ｂ２Ｏ３の含有量が少な過ぎると、熱的安定性が低下して、焼成時にガラスが失透し易くなるため、裏面電極の機械的強度が低下し易くなる。また、焼成時にガラスが完全に失透すると、Ａｌ粉末とＳｉの反応を適正化し難くなり、ＢＳＦ効果を享受し難くなる。一方、Ｂ２Ｏ３の含有量が多過ぎると、ガラスが分相し易くなるため、Ａｌ−Ｓｉ合金層とＡｌドープ層を均一に形成し難くなる。 B 2 O 3 is a component that forms a glass skeleton, and its content is 10 to 66%, preferably 35 to 60%, more preferably 40 to 58%, and particularly preferably 45 to 55%. When the content of B 2 O 3 is too small, the thermal stability is lowered, and the glass is liable to devitrify during firing, the mechanical strength of the back electrode tends to decrease. Further, when the glass is completely devitrified during firing, it is difficult to optimize the reaction between the Al powder and Si, and it is difficult to enjoy the BSF effect. On the other hand, when the content of B 2 O 3 is too large, the glass is likely to be phase-separated, so that it is difficult to uniformly form the Al—Si alloy layer and the Al-doped layer.

ＣａＯは、熱水による電極の耐劣化性を高める成分であると共に、ブリスターやＡｌの凝集を抑制する成分であり、その含有量は０．１〜２５％、１〜２０％、３〜１８％、５〜１５％、特に７〜１３％が好ましい。ＣａＯの含有量が少な過ぎると、上記効果を享受し難くなる。一方、ＣａＯの含有量が多過ぎると、軟化点が高くなり過ぎて、焼成時にガラスが溶け難くなるため、Ａｌ粉末とＳｉの反応が過剰になり、結果として、Ａｌ−Ｓｉ合金層とＡｌドープ層が過剰に形成されて、シリコン太陽電池の光電変換効率が低下し易くなる。また、裏面電極の焼結性が低下するため、裏面電極の機械的強度が低下し易くなる。   CaO is a component that enhances the deterioration resistance of the electrode due to hot water, and is a component that suppresses aggregation of blisters and Al, and its content is 0.1 to 25%, 1 to 20%, and 3 to 18%. 5 to 15%, particularly 7 to 13% is preferable. When there is too little content of CaO, it will become difficult to receive the said effect. On the other hand, if the content of CaO is too large, the softening point becomes too high and the glass becomes difficult to melt during firing, so that the reaction between the Al powder and Si becomes excessive, resulting in an Al-Si alloy layer and an Al dope. The layer is formed excessively, and the photoelectric conversion efficiency of the silicon solar cell is likely to decrease. Further, since the sinterability of the back electrode is lowered, the mechanical strength of the back electrode is likely to be lowered.

上記成分以外にも、例えば、以下の成分を添加することができる。   In addition to the above components, for example, the following components can be added.

ＳｉＯ２は、熱的安定性を高める成分である。ＳｉＯ２の含有量は０〜２０％、０．１〜１５％、１〜１３％、特に５〜１２％が好ましい。ＳｉＯ２の含有量が多過ぎると、軟化点が高くなり過ぎて、焼成時にガラスが溶け難くなるため、Ａｌ粉末とＳｉの反応が過剰になり、結果として、Ａｌ−Ｓｉ合金層とＡｌドープ層が過剰に形成されて、シリコン太陽電池の光電変換効率が低下し易くなる。また、裏面電極の焼結性が低下するため、裏面電極の機械的強度が低下し易くなる。 SiO 2 is a component that enhances thermal stability. The content of SiO 2 is preferably 0 to 20%, 0.1 to 15%, 1 to 13%, particularly 5 to 12%. If the content of SiO 2 is too large, the softening point becomes too high and the glass is difficult to melt during firing, so the reaction between Al powder and Si becomes excessive, and as a result, the Al—Si alloy layer and the Al doped layer Is excessively formed, and the photoelectric conversion efficiency of the silicon solar cell is likely to be lowered. Further, since the sinterability of the back electrode is lowered, the mechanical strength of the back electrode is likely to be lowered.

Ａｌ２Ｏ３は、熱的安定性を高める成分である。Ａｌ２Ｏ３の含有量は０〜１０％、０〜５％、特に０．１〜２％が好ましい。Ａｌ２Ｏ３の含有量が多過ぎると、軟化点が高くなり過ぎて、焼成時にガラスが溶け難くなるため、Ａｌ粉末とＳｉの反応が過剰になり、結果として、Ａｌ−Ｓｉ合金層とＡｌドープ層が過剰に形成されて、シリコン太陽電池の光電変換効率が低下し易くなる。また、裏面電極の焼結性が低下するため、裏面電極の機械的強度が低下し易くなる。 Al 2 O 3 is a component that enhances thermal stability. The content of Al 2 O 3 is preferably 0 to 10%, 0 to 5%, particularly preferably 0.1 to 2%. If the content of Al 2 O 3 is too large, the softening point becomes too high and the glass becomes difficult to melt during firing, so the reaction between the Al powder and Si becomes excessive, and as a result, the Al—Si alloy layer and the Al Doped layers are formed excessively, and the photoelectric conversion efficiency of the silicon solar cell is likely to be lowered. Further, since the sinterability of the back electrode is lowered, the mechanical strength of the back electrode is likely to be lowered.

ＳｉＯ２＋Ａｌ２Ｏ３は、熱的安定性を高める成分である。ＳｉＯ２＋Ａｌ２Ｏ３の含有量は０〜２０％、０．１〜２０％、１〜１８％、３〜１５％、５〜１４％、特に８〜１３％が好ましい。ＳｉＯ２＋Ａｌ２Ｏ３の含有量が多過ぎると、軟化点が高くなり過ぎて、焼成時にガラスが溶け難くなるため、Ａｌ粉末とＳｉの反応が過剰になり、結果として、Ａｌ−Ｓｉ合金層とＡｌドープ層が過剰に形成されて、シリコン太陽電池の光電変換効率が低下し易くなる。また、裏面電極の焼結性が低下するため、裏面電極の機械的強度が低下し易くなる。 SiO 2 + Al 2 O 3 is a component that enhances thermal stability. The content of SiO 2 + Al 2 O 3 is preferably 0 to 20%, 0.1 to 20%, 1 to 18%, 3 to 15%, 5 to 14%, particularly 8 to 13%. If the content of SiO 2 + Al 2 O 3 is too large, the softening point becomes too high, and the glass becomes difficult to melt at the time of firing, so the reaction between Al powder and Si becomes excessive, resulting in an Al—Si alloy layer. As a result, the Al-doped layer is excessively formed, and the photoelectric conversion efficiency of the silicon solar cell is likely to be lowered. Further, since the sinterability of the back electrode is lowered, the mechanical strength of the back electrode is likely to be lowered.

Ｌｉ２Ｏは、軟化点を下げる成分であり、またビークルに含まれる樹脂の燃焼効率を高める成分であるが、その含有量が多過ぎると、ガラスが分相し易くなり、またガラス本来の耐水性が低下し易くなる。Ｌｉ２Ｏの含有量は０〜１０％、０．１〜５％、特に１〜３％が好ましい。 Li 2 O is a component that lowers the softening point and is a component that increases the combustion efficiency of the resin contained in the vehicle. However, if the content is too large, the glass tends to phase-separate, and the inherent water resistance of the glass The property tends to decrease. The content of Li 2 O is preferably 0 to 10%, 0.1 to 5%, particularly preferably 1 to 3%.

Ｎａ２Ｏは、軟化点を下げる成分であり、またビークルに含まれる樹脂の燃焼効率を高める成分であるが、その含有量が多過ぎると、ガラス本来の耐水性が低下し易くなる。Ｎａ２Ｏの含有量は０〜１２％、０．１〜８％、特に１〜５％が好ましい。 Na 2 O is a component that lowers the softening point and is a component that enhances the combustion efficiency of the resin contained in the vehicle. However, if the content is too large, the inherent water resistance of the glass tends to decrease. The content of Na 2 O is preferably 0 to 12%, 0.1 to 8%, particularly preferably 1 to 5%.

Ｌｉ２Ｏ＋Ｎａ２Ｏは、軟化点を下げる成分であり、またビークルに含まれる樹脂の燃焼効率を高める成分であるが、その含有量が多過ぎると、ガラス本来の耐水性が低下し易くなる。Ｎａ２Ｏの含有量は０〜１２％、０．１〜８％、特に１〜５％が好ましい。 Li 2 O + Na 2 O is a component that lowers the softening point and is a component that enhances the combustion efficiency of the resin contained in the vehicle. However, if the content is too large, the inherent water resistance of the glass tends to decrease. The content of Na 2 O is preferably 0 to 12%, 0.1 to 8%, particularly preferably 1 to 5%.

Ｋ２Ｏは、軟化点を下げる成分であるが、溶融時に分相を促進する作用を有する。Ｋ２Ｏの含有量は０〜１０％、０〜５％、特に０〜３％が好ましい。 K 2 O is a component that lowers the softening point, but has the effect of promoting phase separation during melting. The content of K 2 O is preferably 0 to 10%, 0 to 5%, particularly preferably 0 to 3%.

ＭｇＯは、ブリスターやＡｌの凝集を抑制する成分であり、その含有量は０〜５％、０〜３％、特に０〜１％が好ましい。ＭｇＯの含有量が多過ぎると、軟化点が高くなり過ぎて、焼成時にガラスが溶け難くなるため、Ａｌ粉末とＳｉの反応が過剰になり、結果として、Ａｌ−Ｓｉ合金層とＡｌドープ層が過剰に形成されて、シリコン太陽電池の光電変換効率が低下し易くなる。また、裏面電極の焼結性が低下するため、裏面電極の機械的強度が低下し易くなる。   MgO is a component that suppresses aggregation of blisters and Al, and its content is preferably 0 to 5%, 0 to 3%, particularly preferably 0 to 1%. If the content of MgO is too large, the softening point becomes too high and the glass becomes difficult to melt during firing, so that the reaction between Al powder and Si becomes excessive, resulting in an Al-Si alloy layer and an Al-doped layer. When formed excessively, the photoelectric conversion efficiency of the silicon solar cell tends to decrease. Further, since the sinterability of the back electrode is lowered, the mechanical strength of the back electrode is likely to be lowered.

ＳｒＯは、ブリスターやＡｌの凝集を抑制する成分であり、その含有量は０〜１５％、０〜１０％、特に０〜５％が好ましい。ＳｒＯの含有量が多過ぎると、熱的安定性が低下し易くなる。   SrO is a component that suppresses the aggregation of blisters and Al, and its content is preferably 0 to 15%, 0 to 10%, particularly preferably 0 to 5%. When there is too much content of SrO, thermal stability will fall easily.

ＢａＯは、ブリスターやＡｌの凝集を抑制する成分であると共に、熱的安定性を高める成分であり、その含有量は０〜２０％、０〜１５％、０．１〜１０％、１〜９％、特に２〜８％が好ましい。ＢａＯの含有量が多過ぎると、ガラス組成の成分バランスが損なわれて、逆に熱的安定性が低下し易くなる。   BaO is a component that suppresses aggregation of blisters and Al, and is a component that enhances thermal stability, and its content is 0 to 20%, 0 to 15%, 0.1 to 10%, and 1 to 9 %, Particularly 2 to 8% is preferred. When there is too much content of BaO, the component balance of a glass composition will be impaired and conversely thermal stability will fall easily.

ＺｎＯは、熱的安定性を高める成分であり、その含有量は０〜１２％、０〜１０％、特に１〜９％である。ＺｎＯの含有量が多過ぎると、ブリスターやＡｌの凝集が生じ易くなる。なお、ブリスターやＡｌの凝集を完全に抑制する観点からは、実質的にＺｎＯを含有しないことが好ましい。ここで、「実質的にＺｎＯを含有しない」とは、ガラス組成中のＺｎＯの含有量が１０００ｐｐｍ（質量）未満の場合を指す。   ZnO is a component that enhances thermal stability, and its content is 0 to 12%, 0 to 10%, particularly 1 to 9%. When there is too much content of ZnO, it will become easy to produce aggregation of blister and Al. In addition, it is preferable not to contain ZnO substantially from a viewpoint of completely suppressing blister and aggregation of Al. Here, “substantially does not contain ZnO” refers to a case where the content of ZnO in the glass composition is less than 1000 ppm (mass).

ＣｕＯは、熱的安定性を高める成分であり、その含有量は０〜２０％、０．１〜１５％、特に５〜１３％が好ましい。ＣｕＯの含有量が多過ぎると、ガラス組成の成分バランスが損なわれて、逆に熱的安定性が低下し易くなる。   CuO is a component that enhances thermal stability, and its content is preferably 0 to 20%, 0.1 to 15%, and particularly preferably 5 to 13%. When there is too much content of CuO, the component balance of a glass composition will be impaired and conversely thermal stability will fall easily.

Ｆｅ２Ｏ３は、熱的安定性を高める成分であり、その含有量は０〜７％、０〜４％、特に０〜３％が好ましい。Ｆｅ２Ｏ３の含有量が多過ぎると、ガラス組成の成分バランスが損なわれて、逆に熱的安定性が低下し易くなる。 Fe 2 O 3 is a component that enhances thermal stability, and its content is preferably 0 to 7%, 0 to 4%, particularly preferably 0 to 3%. When the content of Fe 2 O 3 is too large, is impaired balance of components glass composition, thermal stability tends to decrease in reverse.

Ｓｂ２Ｏ３＋Ｎｄ２Ｏ３＋ＷＯ３＋Ｉｎ２Ｏ３＋Ｇａ２Ｏ３＋Ｐ２Ｏ５（Ｆｅ２Ｏ３、Ｓｂ２Ｏ３、Ｎｄ２Ｏ３、ＷＯ３、Ｉｎ２Ｏ３、Ｇａ２Ｏ３、及びＰ２Ｏ５の合量）は、熱的安定性を高める成分であり、その含有量は０〜１０％、特に０〜５％である。Ｓｂ２Ｏ３＋Ｎｄ２Ｏ３＋ＷＯ３＋Ｉｎ２Ｏ３＋Ｇａ２Ｏ３＋Ｐ２Ｏ５の含有量が多過ぎると、バッチコストが高騰する。なお、Ｆｅ２Ｏ３、Ｓｂ２Ｏ３、Ｎｄ２Ｏ３、ＷＯ３、Ｉｎ２Ｏ３、Ｇａ２Ｏ３、Ｐ２Ｏ５の含有量は、各々０〜２％が好ましい。 Sb 2 O 3 + Nd 2 O 3 + WO 3 + In 2 O 3 + Ga 2 O 3 + P 2 O 5 (Fe 2 O 3 , Sb 2 O 3 , Nd 2 O 3 , WO 3 , In 2 O 3 , Ga 2 O 3 , And the total amount of P 2 O 5 ) is a component that enhances thermal stability, and its content is 0 to 10%, particularly 0 to 5%. When the content of Sb 2 O 3 + Nd 2 O 3 + WO 3 + In 2 O 3 + Ga 2 O 3 + P 2 O 5 is too large, batch cost soars. The content of Fe 2 O 3, Sb 2 O 3, Nd 2 O 3, WO 3, In 2 O 3, Ga 2 O 3, P 2 O 5 , respectively 0-2% is preferred.

ＭｏＯ３＋Ｌａ２Ｏ３＋Ｙ２Ｏ３＋ＣｅＯ２（ＭｏＯ３、Ｌａ２Ｏ３、Ｙ２Ｏ３、及びＣｅＯ２の合量）は、溶融時の分相を抑制する効果があるが、ＭｏＯ３＋Ｌａ２Ｏ３＋Ｙ２Ｏ３＋ＣｅＯ２の含有量が多過ぎると、バッチコストが高騰する。よって、ＭｏＯ３＋Ｌａ２Ｏ３＋Ｙ２Ｏ３＋ＣｅＯ２の含有量は０〜５％が好ましい。なお、ＭｏＯ３、Ｌａ２Ｏ３、Ｙ２Ｏ３、ＣｅＯ２の含有量は、各々０〜２％が好ましい。 MoO 3 + La 2 O 3 + Y 2 O 3 + CeO 2 (total amount of MoO 3 , La 2 O 3 , Y 2 O 3 , and CeO 2 ) has an effect of suppressing phase separation during melting, but MoO 3 + When the content of La 2 O 3 + Y 2 O 3 + CeO 2 is too large, batch cost soars. Therefore, the content of MoO 3 + La 2 O 3 + Y 2 O 3 + CeO 2 is preferably 0 to 5%. Incidentally, MoO 3, La 2 O 3 , Y 2 O 3, the content of CeO 2 are each 0 to 2% is preferred.

本発明の電極形成用ガラスは、ＰｂＯの含有を完全に排除するものではないが、上記の通り、環境的観点から実質的にＰｂＯを含有しないことが好ましい。   Although the glass for electrode formation of the present invention does not completely exclude the inclusion of PbO, as described above, it is preferable that the glass does not substantially contain PbO from the environmental viewpoint.

本発明の電極形成材料は、上記の電極形成用ガラスからなるガラス粉末と、金属粉末と、ビークルとを含む。ガラス粉末は、Ａｌ粉末を結合させて、電極を形成する成分であると共に、Ａｌ粉末とＳｉの反応に影響を及ぼすことにより、Ａｌ−Ｓｉ合金層とＡｌドープ層を適正に形成させる成分である。金属粉末は、電極を形成する主要成分であり、導電性を確保するための成分である。ビークルは、ペースト化するための成分であり、印刷に適した粘度を付与するための成分である。   The electrode forming material of the present invention includes glass powder made of the above electrode forming glass, metal powder, and a vehicle. Glass powder is a component that forms an electrode by bonding Al powder, and that appropriately forms an Al-Si alloy layer and an Al-doped layer by affecting the reaction between Al powder and Si. . The metal powder is a main component for forming the electrode and a component for ensuring conductivity. The vehicle is a component for making a paste, and a component for imparting a viscosity suitable for printing.

本発明の電極形成材料において、ガラス粉末の軟化点は５００〜６００℃、５２０〜５８０℃、特に５３０〜５７０℃が好ましい。軟化点が５００℃より低いと、熱水による電極の耐劣化性が低下する傾向があるため、高温多湿環境下でＡｌ電極とＨ２Ｏの反応により、水素ガスが発生し、電極としての機能が低下し易くなる。一方、軟化点が６００℃より高いと、焼成時にガラス粉末が溶け難くなるため、Ａｌ粉末とＳｉの反応が過剰になり、Ａｌ−Ｓｉ合金層とＡｌドープ層が過剰に形成されて、シリコン太陽電池の光電変換効率が低下し易くなると共に、ブリスターやＡｌの凝集が発生し易くなる。ここで、「軟化点」とは、マクロ型示差熱分析（ＤＴＡ）装置で測定した値を指し、ＤＴＡは室温から測定を開始し、昇温速度は１０℃／分とする。なお、軟化点は、図１に示すマクロ型ＤＴＡ装置の測定データにおいて、第四屈曲点の温度（Ｔｓ）を指す。 In the electrode forming material of the present invention, the softening point of the glass powder is preferably 500 to 600 ° C, 520 to 580 ° C, particularly preferably 530 to 570 ° C. When the softening point is lower than 500 ° C., the resistance to deterioration of the electrode due to hot water tends to be reduced. Therefore, hydrogen gas is generated due to the reaction between the Al electrode and H 2 O in a high-temperature and high-humidity environment. Tends to decrease. On the other hand, if the softening point is higher than 600 ° C., the glass powder becomes difficult to melt at the time of firing, so the reaction between Al powder and Si becomes excessive, the Al—Si alloy layer and the Al doped layer are formed excessively, and silicon solar The photoelectric conversion efficiency of the battery tends to decrease, and blisters and Al agglomeration easily occur. Here, the “softening point” refers to a value measured with a macro-type differential thermal analysis (DTA) apparatus, DTA starts measurement from room temperature, and the rate of temperature rise is 10 ° C./min. The softening point indicates the temperature (Ts) at the fourth bending point in the measurement data of the macro DTA apparatus shown in FIG.

本発明の電極形成材料において、ガラス粉末の平均粒子径Ｄ５０は３μｍ以下、２μｍ以下、特に１．５μｍ以下が好ましい。ガラス粉末の平均粒子径Ｄ５０が３μｍより大きいと、微細な電極パターンを形成し難くなるため、シリコン太陽電池の光電変換効率が低下し易くなる。一方、ガラス粉末の平均粒子径Ｄ５０の下限は特に限定されないが、ガラス粉末の平均粒子径Ｄ５０が小さ過ぎると、ガラス粉末のハンドリング性や材料収率が低下し易くなる。このような状況を考慮すれば、ガラス粉末の平均粒子径Ｄ５０は０．３μｍ以上が好ましい。なお、（１）ガラスフィルムをボールミルで粉砕した後、得られたガラス粉末を空気分級、或いは（２）ガラスフィルムをボールミル等で粗粉砕した後、ビーズミル等で湿式粉砕すれば、上記平均粒子径Ｄ５０を有するガラス粉末を作製することができる。 In the electrode forming material of the present invention, the average particle diameter D 50 of the glass powder is 3μm or less, 2 [mu] m or less, especially 1.5μm or less. Since the average particle diameter D 50 of the glass powder is hardly formed and 3μm greater than the fine electrode pattern, the photoelectric conversion efficiency of the silicon solar cells tends to decrease. On the other hand, the lower limit of the average particle diameter D 50 of the glass powder is not particularly limited, the average particle diameter D 50 of the glass powder is too small, the handling property and material yield of the glass powder tends to decrease. In view of such situation, the average particle diameter D 50 of the glass powder is preferably at least 0.3 [mu] m. (1) After the glass film is pulverized with a ball mill, the obtained glass powder is classified by air, or (2) The glass film is coarsely pulverized with a ball mill or the like and then wet pulverized with a bead mill or the like. it can be produced glass powder having a D 50.

本発明の電極形成材料において、ガラス粉末の最大粒子径Ｄｍａｘは２５μｍ以下、２０μｍ以下、１５μｍ以下、１０μｍ以下、特に１０μｍ未満が好ましい。ガラス粉末の最大粒子径Ｄｍａｘが２５μｍより大きいと、微細な電極パターンを形成し難くなるため、シリコン太陽電池の光電変換効率が低下し易くなる。ここで、「最大粒子径Ｄｍａｘ」は、レーザー回折法で測定した値を指し、レーザー回折法により測定した際の体積基準の累積粒度分布曲線において、その積算量が粒子の小さい方から累積して９９％である粒子径を表す。 In the electrode forming material of the present invention, the maximum particle diameter Dmax of the glass powder is preferably 25 μm or less, 20 μm or less, 15 μm or less, 10 μm or less, particularly preferably less than 10 μm. When the maximum particle diameter Dmax of the glass powder is larger than 25 μm, it becomes difficult to form a fine electrode pattern, and thus the photoelectric conversion efficiency of the silicon solar cell tends to be lowered. Here, the “maximum particle diameter D max ” refers to a value measured by the laser diffraction method. In the volume-based cumulative particle size distribution curve measured by the laser diffraction method, the accumulated amount is accumulated from the smaller particle. The particle diameter is 99%.

本発明の電極形成材料において、ガラス粉末の含有量は０．２〜１０質量％、０．５〜６質量％、０．７〜４質量％、特に１〜３質量％が好ましい。ガラス粉末の含有量が０．２質量％より少ないと、ブリスターやＡｌの凝集が生じ易くなることに加えて、裏面電極の機械的強度が低下し易くなる。一方、ガラス粉末の含有量が１０質量％より多いと、焼成後にガラスが偏析し易くなり、裏面電極の導電性が低下して、シリコン太陽電池の光電変換効率が低下するおそれがある。また、ガラス粉末の含有量と金属粉末の含有量は、上記と同様の理由により、質量比で０．３：９９．７〜１３：８７、１．５：９８．５〜７：９３、特に１．８：９８．２〜４：９６が好ましい。   In the electrode forming material of the present invention, the glass powder content is preferably 0.2 to 10% by mass, 0.5 to 6% by mass, 0.7 to 4% by mass, and particularly preferably 1 to 3% by mass. When the content of the glass powder is less than 0.2% by mass, in addition to easy aggregation of blisters and Al, the mechanical strength of the back electrode is likely to decrease. On the other hand, if the content of the glass powder is more than 10% by mass, the glass tends to segregate after firing, the conductivity of the back electrode is lowered, and the photoelectric conversion efficiency of the silicon solar cell may be lowered. In addition, the content of the glass powder and the content of the metal powder are 0.3: 99.7 to 13:87, 1.5: 98.5 to 7:93 in mass ratios for the same reason as described above, in particular. 1.8: 98.2 to 4:96 are preferred.

本発明の電極形成材料において、ガラス粉末と金属粉末の含有量は、体積比で１：９９〜１０：９０、２：９８〜６：９４、特に２．５：９７．５〜５：９５が好ましい。ガラス粉末の含有量が少なくなると、ブリスターやＡｌの凝集が生じ易くなることに加えて、裏面電極の機械的強度が低下し易くなる。一方、ガラス粉末の含有量が多くなると、焼成後にガラスが偏析し易くなるため、裏面電極の導電性が低下して、シリコン太陽電池の光電変換効率が低下するおそれがある。   In the electrode forming material of the present invention, the volume ratio of the glass powder and the metal powder is 1:99 to 10:90, 2:98 to 6:94, and particularly 2.5: 97.5 to 5:95 in volume ratio. preferable. When the content of the glass powder is reduced, the mechanical strength of the back electrode is likely to be lowered in addition to the tendency of blisters and agglomeration of Al. On the other hand, when the content of the glass powder increases, the glass tends to segregate after firing, so that the conductivity of the back electrode is lowered and the photoelectric conversion efficiency of the silicon solar cell may be lowered.

本発明の電極形成材料において、金属粉末の含有量は５０〜９７質量％、６５〜９５質量％、特に７０〜９２質量％が好ましい。金属粉末の含有量が５０質量％より少ないと、裏面電極の導電性が低下して、シリコン太陽電池の光電変換効率が低下し易くなる。一方、金属粉末の含有量が９７質量％より多いと、ガラス粉末の含有量が相対的に低下するため、Ａｌ−Ｓｉ合金層とＡｌドープ層を適正に形成し難くなる。   In the electrode forming material of the present invention, the content of the metal powder is preferably 50 to 97 mass%, 65 to 95 mass%, particularly preferably 70 to 92 mass%. When the content of the metal powder is less than 50% by mass, the conductivity of the back electrode is lowered, and the photoelectric conversion efficiency of the silicon solar cell is likely to be lowered. On the other hand, when the content of the metal powder is more than 97% by mass, the content of the glass powder is relatively lowered, so that it is difficult to properly form the Al—Si alloy layer and the Al doped layer.

本発明の電極形成材料において、金属粉末はＡｇ、Ａｌ、Ａｕ、Ｃｕ、Ｐｄ、Ｐｔ及びこれらの合金の一種又は二種以上が好ましく、Ａｌ及びその合金はＢＳＦ効果を享受する観点から特に好ましい。これらの金属粉末は、導電性が良好であると共に、本発明に係るビスマス系ガラスと適合性が良好である。よって、これらの金属粉末を用いると、焼成時にガラス中に発泡が生じ難くなると共に、ガラスが失透し難くなる。また、微細な電極パターンを形成する観点から、金属粉末の平均粒子径Ｄ５０は５μｍ以下、３μｍ以下、２μｍ以下、特に１μｍ以下が好ましい。 In the electrode forming material of the present invention, the metal powder is preferably one or more of Ag, Al, Au, Cu, Pd, Pt and alloys thereof, and Al and alloys thereof are particularly preferable from the viewpoint of enjoying the BSF effect. These metal powders have good conductivity and good compatibility with the bismuth glass according to the present invention. Therefore, when these metal powders are used, foaming hardly occurs in the glass during firing, and the glass is difficult to devitrify. Further, from the viewpoint of forming a fine electrode pattern, the average particle diameter D 50 of the metal powder is preferably 5 μm or less, 3 μm or less, 2 μm or less, and particularly preferably 1 μm or less.

本発明の電極形成材料において、ビークルの含有量は５〜５０質量％、特に１０〜３０質量％が好ましい。ビークルの含有量が５質量％より少ないと、ペースト化が困難になり、厚膜法で電極を形成し難くなる。一方、ビークルの含有量が５０質量％より多いと、焼成前後で膜厚や膜幅が変動し易くなるため、所望の電極パターンを形成し難くなる。   In the electrode forming material of the present invention, the content of the vehicle is preferably 5 to 50% by mass, particularly preferably 10 to 30% by mass. When the content of the vehicle is less than 5% by mass, it becomes difficult to form a paste and it is difficult to form an electrode by the thick film method. On the other hand, when the content of the vehicle is more than 50% by mass, the film thickness and the film width are likely to fluctuate before and after firing, so that it is difficult to form a desired electrode pattern.

上記の通り、ビークルは、一般的に、有機溶媒中に樹脂を溶解させたものを指す。樹脂としては、アクリル酸エステル（アクリル樹脂）、エチルセルロース、ポリエチレングリコール誘導体、ニトロセルロース、ポリメチルスチレン、ポリエチレンカーボネート、メタクリル酸エステル等が使用可能である。特に、アクリル酸エステル、ニトロセルロース、エチルセルロースは、熱分解性が良好であるため、好ましい。有機溶媒としては、Ｎ、Ｎ’−ジメチルホルムアミド（ＤＭＦ）、α−ターピネオール、高級アルコール、γ−ブチルラクトン（γ−ＢＬ）、テトラリン、ブチルカルビトールアセテート、酢酸エチル、酢酸イソアミル、ジエチレングリコールモノエチルエーテル、ジエチレングリコールモノエチルエーテルアセテート、ベンジルアルコール、トルエン、３−メトキシ−３−メチルブタノール、水、トリエチレングリコールモノメチルエーテル、トリエチレングリコールジメチルエーテル、ジプロピレングリコールモノメチルエーテル、ジプロピレングリコールモノブチルエーテル、トリプロピレングリコールモノメチルエーテル、トリプロピレングリコールモノブチルエーテル、プロピレンカーボネート、ジメチルスルホキシド（ＤＭＳＯ）、Ｎ−メチル−２−ピロリドン等が使用可能である。特に、α−ターピネオールは、高粘性であり、樹脂等の溶解性も良好であるため、好ましい。   As described above, the vehicle generally refers to a resin in which a resin is dissolved in an organic solvent. As the resin, acrylic acid ester (acrylic resin), ethyl cellulose, polyethylene glycol derivative, nitrocellulose, polymethylstyrene, polyethylene carbonate, methacrylic acid ester and the like can be used. In particular, acrylic acid ester, nitrocellulose, and ethylcellulose are preferable because of their good thermal decomposability. As organic solvents, N, N′-dimethylformamide (DMF), α-terpineol, higher alcohol, γ-butyllactone (γ-BL), tetralin, butyl carbitol acetate, ethyl acetate, isoamyl acetate, diethylene glycol monoethyl ether , Diethylene glycol monoethyl ether acetate, benzyl alcohol, toluene, 3-methoxy-3-methylbutanol, water, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl Ether, tripropylene glycol monobutyl ether, propylene carbonate, dimethyl sulfoxide (DMSO) N- methyl-2-pyrrolidone and the like can be used. In particular, α-terpineol is preferable because it is highly viscous and has good solubility in resins and the like.

本発明の電極形成材料は、上記成分以外にも、熱膨張係数を調整するためにコーディエライト等のセラミックフィラー粉末、電極の表面抵抗を調整するためにＮｉＯ等の酸化物粉末、ペースト特性を調整するために界面活性剤、増粘剤、可塑剤、表面処理剤、色調を調整するために顔料等を含有してもよい。   In addition to the above components, the electrode-forming material of the present invention has ceramic filler powder such as cordierite for adjusting the thermal expansion coefficient, oxide powder such as NiO for adjusting the surface resistance of the electrode, and paste characteristics. In order to adjust, a surfactant, a thickener, a plasticizer, a surface treatment agent, a pigment or the like may be included to adjust the color tone.

以下、実施例に基づいて、本発明を詳細に説明する。なお、以下の実施例は単なる例示である。本発明は以下の実施例に何ら限定されない。   Hereinafter, based on an Example, this invention is demonstrated in detail. The following examples are merely illustrative. The present invention is not limited to the following examples.

表１、２は、本発明の実施例（試料Ｎｏ．１〜１５）及び比較例（試料Ｎｏ．１６〜１８）を示している。   Tables 1 and 2 show Examples (Sample Nos. 1 to 15) and Comparative Examples (Sample Nos. 16 to 18) of the present invention.

次のようにして、各試料を調製した。まず、表中に示したガラス組成となるように各種酸化物、炭酸塩等のガラス原料を調合して、ガラスバッチを準備した後、このガラスバッチを白金坩堝に入れ、１１００〜１２００℃で１〜２時間溶融した。次に、溶融ガラスの一部を押棒式熱膨張係数測定（ＴＭＡ）用サンプルとしてステンレス製の金型に流し出した。その他の溶融ガラスを水冷ローラーでフィルム状に成形し、得られたガラスフィルムをボールミルで粉砕した後、目開き２５０メッシュの篩を通過させた上で、分級し、表中に示す平均粒子径Ｄ５０のガラス粉末を得た。 Each sample was prepared as follows. First, after preparing glass batches by preparing glass raw materials such as various oxides and carbonates so as to have the glass composition shown in the table, this glass batch was put in a platinum crucible and 1 at 1200 to 1200 ° C. Melted for ~ 2 hours. Next, a part of the molten glass was poured out into a stainless steel mold as a sample for measuring the thermal expansion coefficient of the push rod (TMA). Other molten glass was formed into a film shape with a water-cooled roller, and the obtained glass film was pulverized with a ball mill, then passed through a 250 mesh sieve, classified, and the average particle diameter D shown in the table 50 glass powders were obtained.

各試料につき、平均粒子径Ｄ５０、軟化点、外観、Ａｌドープ層の状態、熱水による電極の耐劣化性を測定した。その結果を表１、２に示す。 For each sample, the average particle diameter D 50 , softening point, appearance, state of the Al-doped layer, and resistance to deterioration of the electrode by hot water were measured. The results are shown in Tables 1 and 2.

平均粒子径Ｄ５０は、レーザー回折法で測定した値であり、レーザー回折法により測定した際の体積基準の累積粒度分布曲線において、その積算量が粒子の小さい方から累積して５０％である粒子径である。 The average particle diameter D 50 is a value measured by a laser diffraction method, in the cumulative particle size distribution curve of the volume-based when measured by a laser diffraction method, the accumulated amount is 50% cumulative from the smaller particle The particle size.

軟化点は、マクロ型ＤＴＡ装置で測定した値である。なお、マクロ型ＤＴＡの測定温度域は室温〜６５０℃とし、昇温速度は１０℃／分とした。   The softening point is a value measured with a macro DTA apparatus. The measurement temperature range of the macro type DTA was room temperature to 650 ° C., and the rate of temperature increase was 10 ° C./min.

得られたガラス粉末２質量％と、Ａｌ粉末（平均粒子径Ｄ５０＝０．５μｍ）７５質量％と、ビークル（α−ターピネオールにアクリル酸エステルを溶解させたもの）２３質量％とを三本ローラーで混練し、ペースト状の試料を得た。次に、スクリーン印刷により、シリコン半導体基板（１００ｍｍ×１００ｍｍ×２００μｍ厚）の裏面であるｐ型層側の全面にペースト状の試料を塗布し、乾燥した後、最高温度７２０℃で短時間焼成（焼成開始から終了まで２分、最高温度で５秒保持）し、厚みが５０μｍの裏面電極を得た。得られた裏面電極につき、裏面電極の表面を目視観察し、ブリスター及びＡｌの凝集の個数を観察することで外観を評価した。具体的には、ブリスター及びＡｌの凝集の個数が２個以下の場合を「○」、３〜５個の場合を「△」、６個以上の場合を「×」として、評価した。 Three pieces of 2% by weight of the obtained glass powder, 75% by weight of Al powder (average particle diameter D 50 = 0.5 μm), and 23% by weight of vehicle (a solution of acrylic ester dissolved in α-terpineol) A paste-like sample was obtained by kneading with a roller. Next, a paste-like sample is applied to the entire surface of the p-type layer side, which is the back surface of the silicon semiconductor substrate (100 mm × 100 mm × 200 μm thick) by screen printing, dried, and then fired at a maximum temperature of 720 ° C. for a short time ( 2 minutes from the start to the end of firing, and held at the maximum temperature for 5 seconds) to obtain a back electrode having a thickness of 50 μm. About the obtained back electrode, the external appearance was evaluated by visually observing the surface of the back electrode and observing the number of blisters and the aggregation of Al. Specifically, the case where the number of aggregates of blisters and Al was 2 or less was evaluated as “◯”, the case of 3 to 5 as “Δ”, and the case of 6 or more as “X”.

次のようにして、Ａｌドープ層の状態を評価した。外観の評価に用いた評価試料をＳＥＭ（マッピング）で観察し、裏面電極側からシリコン半導体基板中のｐｎジャンクションの手前までＡｌドープ層が形成されているものを「○」、それ以外を「×」として評価した。   The state of the Al doped layer was evaluated as follows. The evaluation sample used for the appearance evaluation is observed with SEM (mapping). “O” indicates that the Al doped layer is formed from the back electrode side to the pn junction in the silicon semiconductor substrate, and “X” indicates the other. ".

次のようにして、熱水による電極の耐劣化性を評価した。上記のペースト状の試料を用いて、常法に従い、裏面電極が形成されたセルを作製した。次に、このセルを８０℃のＨ２Ｏ中に５分間浸漬させた時に、裏面電極からガスが発生しなかったものを「○」、ガスが発生したものを「×」として評価した。 In the following manner, the deterioration resistance of the electrode by hot water was evaluated. Using the above paste-like sample, a cell having a back electrode formed was produced according to a conventional method. Next, when this cell was immersed in H 2 O at 80 ° C. for 5 minutes, the case where no gas was generated from the back electrode was evaluated as “◯”, and the case where gas was generated was evaluated as “X”.

表１、２から明らかなように、試料Ｎｏ．１〜１２は、Ａｌドープ層、外観、熱水による電極の耐劣化性の評価が良好であった。一方、試料Ｎｏ．１３は、外観と熱水による電極の耐劣化性の評価が不良であった。試料Ｎｏ．１４は、熱水による電極の耐劣化性の評価が不良であった。試料Ｎｏ．１５は、Ａｌドープ層の評価が不良であった。   As apparent from Tables 1 and 2, Sample No. In Nos. 1 to 12, the evaluation of the Al-doped layer, the appearance, and the resistance to deterioration of the electrode by hot water was good. On the other hand, sample No. No. 13 was poor in evaluation of the appearance and the deterioration resistance of the electrode by hot water. Sample No. No. 14 was poor in evaluation of the deterioration resistance of the electrode by hot water. Sample No. No. 15 was poor in evaluation of the Al-doped layer.

本発明の電極形成用ガラス及び電極形成材料は、シリコン太陽電池の電極、特にシリコン太陽電池の裏面電極の形成に好適である。更に、本発明の電極形成用ガラス及び電極形成材料は、シリコン太陽電池以外の用途、例えばセラミックコンデンサ等のセラミック電子部品、フォトダイオード等の光学部品に適用することもできる。   The glass for electrode formation and the electrode forming material of the present invention are suitable for forming an electrode of a silicon solar cell, particularly a back electrode of a silicon solar cell. Furthermore, the electrode forming glass and electrode forming material of the present invention can be applied to uses other than silicon solar cells, for example, ceramic electronic components such as ceramic capacitors, and optical components such as photodiodes.

Claims (10)

ガラス組成として、モル％で、Ｂｉ２Ｏ３ １〜３０％、Ｂ２Ｏ３ １０〜６６％、ＣａＯ ０．１〜２５％を含有することを特徴とする電極形成用ガラス。 As a glass composition, in mol%, Bi 2 O 3 1~30% , B 2 O 3 10~66%, glass for electrode formation, wherein the containing CaO 0.1 to 25%. 更に、Ｌｉ２Ｏ＋Ｎａ２Ｏを０．１〜１５モル％含有することを特徴とする請求項１に記載の電極形成用ガラス。 Furthermore, the electrode forming glass according to claim 1, characterized in that it contains Li 2 O + Na 2 O 0.1~15 mol%. 更に、ＳｉＯ２＋Ａｌ２Ｏ３の含有量を０．１〜２０モル％含有することを特徴とする請求項１又は２に記載の電極形成用ガラス。 Furthermore, the electrode forming glass according to claim 1 or 2, characterized in that it contains a content of SiO 2 + Al 2 O 3 0.1~20 mol%. 更に、ＣｕＯを０．１〜１５モル％含有することを特徴とする請求項１〜３の何れか一項に記載の電極形成用ガラス。   Furthermore, 0.1-15 mol% of CuO is contained, The glass for electrode formation as described in any one of Claims 1-3 characterized by the above-mentioned. 実質的にＰｂＯを含有しないことを特徴とする請求項１〜４の何れか一項に記載の電極形成用ガラス。   The electrode forming glass according to any one of claims 1 to 4, wherein the glass does not substantially contain PbO. シリコン太陽電池の裏面電極の形成に用いることを特徴とする請求項１〜５の何れか一項に記載の電極形成用ガラス。   It uses for formation of the back surface electrode of a silicon solar cell, The glass for electrode formation as described in any one of Claims 1-5 characterized by the above-mentioned. 請求項１〜６の何れか一項に記載の電極形成用ガラスからなるガラス粉末と、金属粉末と、ビークルとを含むことを特徴とする電極形成材料。   An electrode forming material comprising glass powder made of the electrode forming glass according to any one of claims 1 to 6, a metal powder, and a vehicle. ガラス粉末の含有量が０．２〜１０質量％であることを特徴とする請求項７に記載の電極形成材料。   The electrode forming material according to claim 7, wherein the content of the glass powder is 0.2 to 10% by mass. 平均粒子径Ｄ５０が３μｍ未満であることを特徴とする請求項７又は８に記載の電極形成材料。 Electrode forming material according to claim 7 or 8, wherein the average particle diameter D 50 is less than 3 [mu] m. 金属粉末として、Ａｌ及びこれらの合金を含むことを特徴とする請求項７〜９の何れか一項に記載の電極形成材料。
The electrode forming material according to any one of claims 7 to 9, comprising Al and an alloy thereof as metal powder.
JP2011151514A 2011-07-08 2011-07-08 Electrode formation glass and electrode formation material Withdrawn JP2013018666A (en)

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Cited By (2)

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CN111180106A (en) * 2018-11-09 2020-05-19 Ａｇｃ株式会社 Glass, glass powder, conductive paste and solar cell
JP2020198380A (en) * 2019-06-04 2020-12-10 Ａｇｃ株式会社 Glass composition, manufacturing method for glass composition, conductive paste, and solar cell

Cited By (5)

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Publication number Priority date Publication date Assignee Title
CN111180106A (en) * 2018-11-09 2020-05-19 Ａｇｃ株式会社 Glass, glass powder, conductive paste and solar cell
JP2020075843A (en) * 2018-11-09 2020-05-21 Ａｇｃ株式会社 Glass, glass powder, electroconductive paste, and solar battery
CN111180106B (en) * 2018-11-09 2023-01-03 Ａｇｃ株式会社 Glass, glass powder, conductive paste and solar cell
JP2020198380A (en) * 2019-06-04 2020-12-10 Ａｇｃ株式会社 Glass composition, manufacturing method for glass composition, conductive paste, and solar cell
JP7444552B2 (en) 2019-06-04 2024-03-06 Ａｇｃ株式会社 Glass composition, method for producing glass composition, conductive paste, and solar cell

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