JP5856277B1

JP5856277B1 - Solar cell electrode paste and solar cell

Info

Publication number: JP5856277B1
Application number: JP2014240619A
Authority: JP
Inventors: 航介角田; 高啓杉山
Original assignee: Noritake Co Ltd
Current assignee: Noritake Co Ltd
Priority date: 2014-11-27
Filing date: 2014-11-27
Publication date: 2016-02-09
Anticipated expiration: 2034-11-27
Also published as: JP2016103547A

Abstract

【課題】接触抵抗が低い電極を形成でき、ＬＤＥ基板に用いた場合にも高出力の太陽電池が得られる太陽電池電極用ペーストおよび高出力の太陽電池セルを提供する。【解決手段】電極用ペーストは、35.0〜83.0(mol%)のTeO2、0.1〜20.0(mol%)のBi2O3、15.5〜30.0(mol%)のLi2O、0.1〜40.0(mol%)のZnOから成るガラス、主成分合計量が95(mol%)以上で、MgO、TiO2、V2O5、Cr2O3、MnO2、Fe2O3、Co3O4、NiO、CuO、WO3のうちの少なくとも１種を含むガラスを含むことから、受光面電極２８をファイヤースルーで形成する。【選択図】図１Provided are a solar cell electrode paste and a high output solar cell, which can form an electrode having a low contact resistance and provide a high output solar cell even when used for an LDE substrate. The electrode paste comprises 35.0 to 83.0 (mol%) TeO2, 0.1 to 20.0 (mol%) Bi2O3, 15.5 to 30.0 (mol%) Li2O, and 0.1 to 40.0 (mol%) ZnO. Since the glass contains a glass containing at least one of MgO, TiO2, V2O5, Cr2O3, MnO2, Fe2O3, Co3O4, NiO, CuO, and WO3, the total amount of main components is 95 (mol%) or more. The electrode 28 is formed by fire-through. [Selection] Figure 1

Description

本発明は、ファイヤースルー法による電極形成に好適に用い得る太陽電池電極用ペーストおよび太陽電池セルに関する。 The present invention relates to a solar cell electrode paste and a solar cell that can be suitably used for electrode formation by a fire-through method.

例えば、一般的な太陽電池は、一導電型を呈する半導体基板の上面に、逆の導電型の半導体層を介して反射防止膜および受光面電極が備えられると共に、下面に裏面電極(以下、これらを区別しないときは単に「電極」という。)が備えられた構造を有しており、受光により半導体のｐｎ接合に生じた電力を電極を通して取り出すようになっている。上記半導体基板は例えばｐ型多結晶半導体であるシリコン基板であって、受光面側の半導体層は例えばｎ⁺層である。また、裏面電極は例えばｐ⁺層を介して備えられている。また、上記反射防止膜は、十分な可視光透過率を保ちつつ表面反射率を低減して受光効率を高めるためのもので、窒化珪素、二酸化チタン、二酸化珪素等の薄膜から成る。 For example, a general solar cell is provided with an antireflection film and a light-receiving surface electrode on the upper surface of a semiconductor substrate exhibiting one conductivity type via a semiconductor layer of opposite conductivity type, and a back electrode (hereinafter referred to as these below) on the lower surface. When not distinguished from each other, it is simply referred to as an “electrode”), and the power generated in the pn junction of the semiconductor by light reception is taken out through the electrode. The semiconductor substrate is, for example, a silicon substrate that is a p-type polycrystalline semiconductor, and the semiconductor layer on the light receiving surface side is, for example, an n ⁺ layer. Further, the back electrode is provided, for example, via a p ⁺ layer. The antireflection film is for reducing the surface reflectance and increasing the light receiving efficiency while maintaining a sufficient visible light transmittance, and is made of a thin film such as silicon nitride, titanium dioxide, or silicon dioxide.

上記の反射防止膜は電気抵抗値が高いことから、半導体のｐｎ接合に生じた電力を効率よく取り出すためには、受光面電極を形成する部分は反射防止膜を除去する必要がある。そこで、太陽電池の受光面電極は、例えば、ファイヤースルーと称される方法で形成される。この電極形成方法では、例えば、前記反射防止膜をｎ⁺層上の全面に設けた後、例えばスクリーン印刷法を用いてその反射防止膜上に導電性ペーストすなわちペースト状の電極材料を適宜の形状で塗布し、焼成処理を施す。これにより、電極材料が加熱溶融させられると同時にこれに接触している反射防止膜が溶融させられ、受光面電極と半導体基板とが接触させられる。上記導電性ペーストは、例えば、銀粉末と、ガラスフリット(ガラス原料を溶融し急冷した後に必要に応じて粉砕したフレーク状または粉末状のガラスのかけら)と、有機質ベヒクルと、有機溶媒とを主成分とするもので、焼成過程において、この導電性ペースト中のガラス成分が反射防止膜を破るので、導電性ペースト中の導体成分とｎ⁺層とによってオーミックコンタクトが形成される。そのため、電極形成に先立って反射防止膜を部分的に除去する場合に比較して工程が簡単になり、除去部分と電極形成位置との位置ずれも生じない利点がある。 Since the above-described antireflection film has a high electric resistance value, it is necessary to remove the antireflection film from the portion where the light-receiving surface electrode is formed in order to efficiently extract the power generated in the pn junction of the semiconductor. Therefore, the light-receiving surface electrode of the solar cell is formed by a method called fire-through, for example. In this electrode formation method, for example, after the antireflection film is provided on the entire surface of the n ⁺ layer, a conductive paste, that is, a paste-like electrode material is appropriately formed on the antireflection film by using, for example, a screen printing method. And apply a baking process. Thus, the electrode material is heated and melted, and at the same time, the antireflection film in contact with the electrode material is melted, and the light receiving surface electrode and the semiconductor substrate are brought into contact with each other. The conductive paste is mainly composed of, for example, silver powder, glass frit (a piece of flaky or powdered glass that is crushed as necessary after melting and quenching the glass raw material), an organic vehicle, and an organic solvent. Since the glass component in the conductive paste breaks the antireflection film in the baking process, an ohmic contact is formed by the conductive component in the conductive paste and the n ⁺ layer. Therefore, the process is simplified as compared with the case where the antireflection film is partially removed prior to electrode formation, and there is an advantage that no positional deviation occurs between the removed portion and the electrode formation position.

上記のような太陽電池の受光面電極形成では、基板と電極との接着強度を確保しつつ、接触抵抗を低くして良好なオーミックコンタクトを確保し延いては電池出力を向上させることが求められている。従来から、これら接着強度および接触抵抗を改善するための提案は種々為されており、更に、環境問題に配慮して、無鉛ガラスを用いて、接着強度と接触抵抗を満足させることが提案されている。 In the formation of the light receiving surface electrode of the solar cell as described above, it is required to improve the battery output by ensuring good ohmic contact by lowering the contact resistance while ensuring the adhesive strength between the substrate and the electrode. ing. Conventionally, various proposals for improving the adhesive strength and contact resistance have been made, and it has been proposed to satisfy the adhesive strength and the contact resistance using lead-free glass in consideration of environmental problems. Yes.

例えば、非鉛系において、電極と半導体基板との間の接触抵抗と、電極のライン抵抗とを共に低くすることを目的として、Te、Bi、Znの含有モル量の総量が酸化物換算で95(mol%)以上のガラスを含む導電性ペーストを用いることが提案されている(例えば特許文献１を参照。)。また、この特許文献１には、これら各成分は、それぞれ酸化物換算で、Teが35〜89(mol%)、Biが1〜20(mol%)、Znが5〜50(mol%)の範囲が好ましいことや、ガラス中にはSi、B、Al、Zr、Ba、Mo、およびLaを合計5(mol%)以下の範囲で含み得ること等が示されている。 For example, in a lead-free system, the total amount of molar amounts of Te, Bi, and Zn is 95 in terms of oxide for the purpose of reducing both the contact resistance between the electrode and the semiconductor substrate and the line resistance of the electrode. It has been proposed to use a conductive paste containing glass (mol%) or more (see, for example, Patent Document 1). In addition, in Patent Document 1, these components are each in terms of oxides, Te of 35 to 89 (mol%), Bi of 1 to 20 (mol%), and Zn of 5 to 50 (mol%). It is shown that the range is preferable, and that glass can contain Si, B, Al, Zr, Ba, Mo, and La in a total range of 5 (mol%) or less.

また、同様な目的で、酸化物換算でTeを35〜90(mol%)、Znを5〜50(mol%)、Biを1〜20(mol%)、Li、Na、Kの少なくとも１種を0.5〜15(mol%)含有するガラスを含む導電性ペーストを用いることが提案されている(例えば特許文献２を参照。)。また、この特許文献２には、酸化物換算でガラス中にMgを8(mol%)以下、Caを5(mol%)以下、SrおよびBaをそれぞれ3(mol%)以下、MnおよびCuをそれぞれ20(mol%)以下、Agを10(mol%)以下、Vを8(mol%)以下、BおよびPをそれぞれ3(mol%)以下、Tiを10(mol%)以下、Coを9(mol%)以下、Nb、Fe、Ni、Al、Zr、Ta、Si、SnおよびSbをそれぞれ3(mol%)以下の範囲で含み得ること等が示されている。 For the same purpose, at least one of Te 35 to 90 (mol%), Zn 5 to 50 (mol%), Bi 1 to 20 (mol%), Li, Na, and K in terms of oxides. It is proposed to use a conductive paste containing glass containing 0.5 to 15 (mol%) (see, for example, Patent Document 2). Further, in Patent Document 2, Mg is 8 (mol%) or less, Ca is 5 (mol%) or less, Sr and Ba are 3 (mol%) or less, Mn and Cu, respectively, in terms of oxide. 20 (mol%) or less, Ag is 10 (mol%) or less, V is 8 (mol%) or less, B and P are 3 (mol%) or less, Ti is 10 (mol%) or less, and Co is 9 It is shown that Nb, Fe, Ni, Al, Zr, Ta, Si, Sn, and Sb can each be contained in a range of 3 (mol%) or less.

また、鉛系ガラスを含まない導電性ペーストを用いて形成された電極を備えて良好な電池特性を有する太陽電池素子を得ることを目的として、Te系ガラスを含む導電性ペーストを用いることが提案されている(例えば特許文献３を参照。)。この特許文献３には、Te系ガラスが酸化物換算でTeを25〜90(mol%)、WおよびMoを合計で5〜60(mol%)、Znを5〜30(mol%)、Biを0.5〜22(mol%)、Alを2〜20(mol%)の範囲で含むものが好ましいことが示されている。 In addition, it is proposed to use a conductive paste containing Te glass for the purpose of obtaining a solar cell element having good battery characteristics with an electrode formed using a conductive paste not containing lead glass. (See, for example, Patent Document 3). In this Patent Document 3, Te-based glass has an oxide conversion of Te of 25 to 90 (mol%), W and Mo in total of 5 to 60 (mol%), Zn of 5 to 30 (mol%), Bi In the range of 0.5 to 22 (mol%) and Al in the range of 2 to 20 (mol%).

また、Pb含有量が0.1(wt%)以下のPbフリー導電性ペーストにおいて良好な太陽電池特性を得ることを目的として、ガラスフリットおよび導電性ペースト中の添加物の少なくとも一方に、Mg、Ca、SrおよびBaのうちの少なくとも一つを、導電性粉末100重量部に対して元素換算で0.1〜10重量部の範囲で含むものとすることが提案されている(例えば特許文献４を参照。)。この特許文献４においては、ガラスフリットは特に限定されないものとされ、Bi₂O₃-B₂O₃-SiO₂-CeO₂-LiO₂-NaO₂系およびSiO₂-B₂O₃-Li₂O系等無鉛ガラスが例示されている。 Further, for the purpose of obtaining good solar cell characteristics in a Pb-free conductive paste with a Pb content of 0.1 (wt%) or less, at least one of additives in the glass frit and the conductive paste includes Mg, Ca, It has been proposed to contain at least one of Sr and Ba in the range of 0.1 to 10 parts by weight in terms of element with respect to 100 parts by weight of the conductive powder (see, for example, Patent Document 4). In this Patent Document 4, the glass frit is not particularly limited, and includes Bi ₂ O ₃ —B ₂ O ₃ —SiO ₂ —CeO ₂ —LiO ₂ —NaO ₂ and SiO ₂ —B ₂ O ₃ —Li _2. O-based lead-free glass is exemplified.

国際公開第２０１４／０４５９００号International Publication No. 2014/045900 国際公開第２０１４／０５０７０３号International Publication No. 2014/050703 特開２０１１−０９６７４８号公報JP 2011-096748 A 特開２００９−１９４１４１号公報JP 2009-194141 A

上述したような無鉛ガラスを用いた導電性ペーストによって受光面電極を形成した太陽電池素子は、基板と電極との高い接着強度と、電気特性(特に低い接触抵抗およびライン抵抗)とを共に満足するように改善を図ったものであるが、未だ十分な結果は得られていない。接着強度は軟化点調整で比較的容易に確保できるものの、無鉛ガラスは鉛ガラスに比較して浸食量の制御性に劣ることから、良好な電気的接触が得られる条件設定が難しいのである。 The solar cell element in which the light-receiving surface electrode is formed by the conductive paste using the lead-free glass as described above satisfies both the high adhesive strength between the substrate and the electrode and the electrical characteristics (particularly the low contact resistance and the line resistance). However, the results have not been obtained yet. Although the adhesive strength can be ensured relatively easily by adjusting the softening point, lead-free glass is inferior in controllability of the amount of erosion compared to lead glass, and it is difficult to set conditions for obtaining good electrical contact.

例えば、前記特許文献１〜３に示される導電性ペーストは、ガラス中に含まれるTeによって電極と基板との界面に存在するガラス中へのAg溶解量が増大するため、接触抵抗が低下すると共に、焼成時の降温中におけるAg析出が抑制されるので適切な焼成条件範囲が広がる利点がある。しかしながら、Teは浸食抑制作用が強いため、添加量が多くなるとファイヤースルーが不十分になって、却って電気特性の低下や最適焼成温度範囲を狭めることになる。そのため、Teガラスを用いる効果は未だ十分に得られていない。 For example, in the conductive pastes shown in Patent Documents 1 to 3, the amount of Ag dissolved in the glass present at the interface between the electrode and the substrate is increased by Te contained in the glass, so that the contact resistance decreases. Since Ag precipitation during temperature reduction during firing is suppressed, there is an advantage that an appropriate firing condition range is expanded. However, since Te has a strong anti-erosion effect, fire-through becomes insufficient when the addition amount is increased, and on the contrary, the electrical characteristics are lowered and the optimum firing temperature range is narrowed. Therefore, the effect of using Te glass has not been sufficiently obtained.

また、上記特許文献１〜３に記載される導電性ペーストは、ガラス中或いはペースト中に種々の金属成分を加えることで浸食量制御を容易にして、延いては電気特性を改善するものである。しかしながら、ガラスの構成成分を多くすると、安定性が高められると共に浸食量制御性が高められる利点がある反面で、ＦＦ値などの太陽電池特性が損なわれる問題がある。 In addition, the conductive pastes described in Patent Documents 1 to 3 facilitate the control of the amount of erosion by adding various metal components in the glass or paste, thereby improving the electrical characteristics. . However, increasing the number of glass components increases the stability and controllability of the erosion amount, but there is a problem that the solar cell characteristics such as the FF value are impaired.

また、太陽電池出力を向上させるための技術としては、例えば、低ドーパント濃度エミッタ(Lightly Doped Emitter；ＬＤＥ)と称されるものがある。ＬＤＥ技術は、受光面側のドナー濃度を従来に比較して低くしてその受光面側の半導体層を薄くしたもので、ＬＤＥ基板を用いてシャローエミッタ構造とすることにより、表面再結合速度が低下するので、より多くの電流を取り出すことが可能になって出力が向上する。しかしながら、ＬＤＥ技術では、表面のドナー濃度が低くされた結果として、Ag-Si間のバリア障壁が増加し、受光面電極のオーミックコンタクトの確保が困難になる問題がある。また、ｐｎ接合が浅くなるため、ファイヤースルーで反射防止膜を十分に破り且つｐｎ接合に電極が侵入しないような高精度の侵入深さ制御が必要になる問題もある。 As a technique for improving the solar cell output, for example, there is a technique called a low dopant concentration emitter (Lightly Doped Emitter; LDE). In the LDE technology, the donor concentration on the light-receiving surface side is made lower than in the past, and the semiconductor layer on the light-receiving surface side is made thinner. Therefore, more current can be taken out and the output is improved. However, the LDE technique has a problem that as a result of the lower donor concentration on the surface, the barrier barrier between Ag and Si increases, and it becomes difficult to ensure ohmic contact of the light-receiving surface electrode. Further, since the pn junction becomes shallow, there is a problem that it is necessary to control the penetration depth with high accuracy so that the antireflection film is sufficiently broken by fire-through and the electrode does not penetrate the pn junction.

しかも、何れもＬＤＥ基板を用いたシャローエミッタ構造については何ら考慮されておらず、これらをＬＤＥ基板に適用すると、電気特性を確保することが一層困難になり、高出力の太陽電池は得られない。これは、以下の理由によるものと考えられる。受光面電極形成時に基板を適度に浸食してオーミックコンタクトを得ようとすると、電極下ではAgとSiの直接接合が多くなり、延いては再結合速度が高くなる。元々再結合速度が高い従来基板では、電極下で再結合速度が高くなっても、開放電圧Vocに対する影響は小さい。これに対して、ＬＤＥ基板を用いた太陽電池では再結合速度が低いことから、電極下で再結合速度が高くなると開放電圧Vocへの影響が大きく、変換効率の低下延いては出力低下が生じ易いのである。 Moreover, no consideration is given to the shallow emitter structure using the LDE substrate, and when these are applied to the LDE substrate, it becomes more difficult to ensure electrical characteristics, and a high-output solar cell cannot be obtained. . This is considered to be due to the following reasons. If an ohmic contact is obtained by appropriately eroding the substrate during the formation of the light-receiving surface electrode, the direct bonding between Ag and Si increases under the electrode, and the recombination speed increases accordingly. With a conventional substrate that originally has a high recombination speed, even if the recombination speed increases under the electrode, the influence on the open circuit voltage Voc is small. On the other hand, since the recombination speed is low in a solar cell using an LDE substrate, if the recombination speed is high under the electrode, the influence on the open circuit voltage Voc is large, resulting in a decrease in conversion efficiency and a decrease in output. It is easy.

また、上述した構造の他に、半導体基板の裏面にパッシベーション膜として機能させる絶縁膜を設け、受光面側と同様にファイヤースルーによってその絶縁膜を破って半導体と電極との接触を確保する構造がある。これは、例えば、受光面から入射した光を裏面で反射する光閉じ込め構造において、その光が裏面電極で吸収される損失を低減する目的で適用される。或いは、シリコン基板としてｎ型半導体基板を用いる両面受光型のシリコン系太陽電池等にも適用される。このような構造の電極形成に使用するｎ⁺層用裏面ペーストにおいても侵入深さ制御や接触抵抗の低減が望まれている。このように、絶縁膜を介して設けられた電極をファイヤースルーによって半導体基板に電気的に接触させた構造では、侵入深さ制御や接触抵抗の低減が太陽電池の表裏に共通の課題となっていた。 In addition to the structure described above, an insulating film that functions as a passivation film is provided on the back surface of the semiconductor substrate, and a structure that ensures the contact between the semiconductor and the electrode by breaking the insulating film by fire-through in the same manner as the light receiving surface side. is there. This is applied, for example, in the light confinement structure in which the light incident from the light receiving surface is reflected on the back surface, in order to reduce the loss of the light absorbed by the back electrode. Alternatively, the present invention is also applied to a double-sided light receiving silicon solar cell using an n-type semiconductor substrate as a silicon substrate. Also in the back paste for n ⁺ layer used for forming an electrode having such a structure, penetration depth control and reduction of contact resistance are desired. As described above, in the structure in which the electrode provided through the insulating film is in electrical contact with the semiconductor substrate by fire-through, penetration depth control and reduction of contact resistance are common problems on both sides of the solar cell. It was.

本発明は、以上の事情を背景として為されたもので、その目的は、基板との接触抵抗が低い電極を形成でき、しかも、ＬＤＥ基板に用いた場合にも高出力の太陽電池が得られる太陽電池電極用ペーストおよび高出力の太陽電池セルを提供することにある。 The present invention has been made against the background described above, and the object thereof is to form an electrode having a low contact resistance with the substrate, and to obtain a high output solar cell even when used for an LDE substrate. The object is to provide a solar cell electrode paste and a high-power solar cell.

斯かる目的を達成するため、第１発明の要旨とするところは、導電性粉末と、無鉛ガラスから成るガラスフリットと、ベヒクルとを含み、半導体基板の一面上に塗布して焼成処理を施すことにより太陽電池の電極をファイヤースルーによって形成するために用いられる太陽電池電極用ペーストであって、前記無鉛ガラスは、それぞれ酸化物換算で35〜83(mol%)のTe、0.1〜20(mol%)のBi、15.5〜30(mol%)のLi、0.1〜40(mol%)のZnを合計95(mol%)以上と、酸化物換算で合計0〜5(mol%)のMg、Ti、V、Cr、Mn、Fe、Co、Ni、Cu、Wとから実質的に成り、Bを含まないことにある。 In order to achieve such an object, the gist of the first invention is that the conductive powder, a glass frit made of lead-free glass, and a vehicle are coated on one surface of the semiconductor substrate and subjected to a firing treatment. A solar cell electrode paste used for forming a solar cell electrode by fire-through, wherein the lead-free glass is 35 to 83 (mol%) Te, 0.1 to 20 (mol%) in terms of oxide, respectively. ) Bi, 15.5 to 30 (mol%) Li, 0.1 to 40 (mol%) Zn in total 95 (mol%) or more, and 0 to 5 (mol%) in total in terms of oxide, Ti, It consists essentially of V, Cr, Mn, Fe, Co, Ni, Cu, W and does not contain B.

また、前記目的を達成するための第２発明の要旨とするところは、導電性粉末と、無鉛ガラスから成るガラスフリットと、ベヒクルとを含み、半導体基板の一面上に塗布して焼成処理を施すことにより太陽電池の電極をファイヤースルーによって形成するために用いられる太陽電池電極用ペーストであって、前記無鉛ガラスは、それぞれ酸化物換算でTeを35〜83(mol%)、Biを0.1〜20(mol%)、Liを10〜30(mol%)、Znを0.1〜40(mol%)の範囲で合計90(mol%)以上の割合で含み、且つ、Wを酸化物換算で0.4〜10(mol%)の範囲の割合で含み、且つ、Mg、Ti、V、Cr、Mn、Fe、Co、Ni、Cuを酸化物換算で合計0〜5(mol%)の範囲内の割合で含むことにある。 The gist of the second invention for achieving the above object is that it includes conductive powder, glass frit made of lead-free glass, and a vehicle, and is applied onto one surface of a semiconductor substrate and subjected to a firing treatment. A solar cell electrode paste used for forming a solar cell electrode by fire-through, wherein the lead-free glass is 35 to 83 (mol%) Te and 0.1 to 20 Bi in terms of oxide, respectively. (mol%), Li in the range of 10 to 30 (mol%), Zn in the range of 0.1 to 40 (mol%) in a total ratio of 90 (mol%) or more, and W in terms of oxide in the range of 0.4 to 10 (Mol%) in a proportion of the range, and Mg, Ti, V, Cr, Mn, Fe, Co, Ni, Cu in terms of oxides in a total range of 0-5 (mol%) There is.

また、前記目的を達成するための第３発明の要旨とするところは、半導体基板上に絶縁膜を介して設けられた電極がその半導体基板に電気的に接触させられた太陽電池セルであって、前記電極は、前記第１発明または前記第２発明の太陽電池電極用ペーストから生成されたことにある。 According to yet gist of the third invention for achieving the above object, there the solar cell which is brought into electrical contact with the semiconductor substrate of the electrode pixel provided via an insulating film on a semiconductor substrate Thus, the electrode is produced from the solar cell electrode paste of the first invention or the second invention.

前記第１発明によれば、太陽電池電極用ペースト中のガラスフリットは、Te、Bi、Li、Znを酸化物換算の合計量で95(mol%)以上、それぞれ酸化物換算でTeを35〜83(mol%)、Biを0.1〜20(mol%)、Liを15.5〜30(mol%)、Znを0.1〜40(mol%)と、更に、Mg、Ti、V、Cr、Mn、Fe、Co、Ni、Cu、Wを酸化物換算で合計0〜5(mol%)とから成り、Bを含まない無鉛ガラスであることから、これを用いて半導体基板に対して電極をファイヤースルーによって形成すると、接触抵抗が低い電極が得られる。そのため、ＦＦ値や変換効率等の電池特性の優れた高出力の太陽電池セルが得られる。 According to the first aspect of the invention, the glass frit in the solar cell electrode paste is composed of Te, Bi, Li, Zn in a total amount of 95 (mol%) or more in terms of oxides, and each of 35 to 10 in terms of oxides. 83 (mol%), the Bi 0.1~20 (mol%), Li a 15.5~30 (mol%), and the 0.1~40 (mol%) Zn, further, Mg, Ti, V, Cr , Mn, Fe , Co, Ni, Cu, become from the total of W oxide in terms 0~5 (mol%), from the lead-free glass der Rukoto free B, fire through the electrode to the semiconductor substrate by using the In this way, an electrode having a low contact resistance can be obtained. Therefore, a high output solar cell having excellent battery characteristics such as FF value and conversion efficiency can be obtained.

前記第２発明によれば、太陽電池電極用ペーストは、Te、Bi、Li、Znを酸化物換算の合計量で90(mol%)以上、それぞれ酸化物換算でTeを35〜83(mol%)、Biを0.1〜20(mol%)、Liを10〜30(mol%)、Znを0.1〜40(mol%)の範囲内の割合で含み、且つ、Wを酸化物換算で0.4〜10(mol%)の範囲内の割合で含み、更に、Mg、Ti、V、Cr、Mn、Fe、Co、Ni、Cuを酸化物換算で合計0〜5(mol%)の範囲内の割合で含む無鉛ガラスから成るガラスフリットが含まれていることから、これを用いて半導体基板に対して電極をファイヤースルーによって形成すると、接触抵抗が低い電極が得られる。そのため、ＦＦ値や変換効率等の電池特性の優れた高出力の太陽電池セルが得られる。 According to the second invention, the solar cell electrode paste comprises Te, Bi, Li, Zn in a total amount of 90 (mol%) or more in terms of oxide, and 35 to 83 (mol%) in terms of oxide, respectively. ), Bi is contained in a proportion within the range of 0.1 to 20 (mol%), Li is within a range of 10 to 30 (mol%), Zn is within a range of 0.1 to 40 (mol%), and W is converted to an oxide in the range of 0.4 to 10 (mol%) in a proportion within the range, further Mg, Ti, V, Cr, Mn, Fe, Co, Ni, Cu in terms of oxides in a proportion within the range of 0 to 5 (mol%) in total Since the glass frit made of lead-free glass is included, when an electrode is formed on the semiconductor substrate by fire-through using the glass frit, an electrode having a low contact resistance can be obtained. Therefore, a high output solar cell having excellent battery characteristics such as FF value and conversion efficiency can be obtained.

前記第３発明によれば、太陽電池セルは、前記第１発明または前記第２発明の太陽電池電極用ペーストを用いてファイヤースルーによって電極が形成されることから、接触抵抗が低い電極を備えるので、ＦＦ値や変換効率等の電池特性の優れた高出力の太陽電池セルが得られる。 According to the third invention, the solar battery cell is provided with an electrode having low contact resistance because the electrode is formed by fire-through using the solar battery electrode paste of the first invention or the second invention. A high-output solar cell excellent in battery characteristics such as FF value and conversion efficiency can be obtained.

なお、前記無鉛ガラスの成分のうち、Teは、網目形成成分として働くもので、前述したように、ガラス中へのAg溶解量を増大させて接触抵抗を低下させて焼成時の降温中におけるAg析出を抑制して適切な焼成条件範囲を広げると共に、半導体基板の浸食抑制作用を有する。これらの作用により、絶縁膜を十分に浸食して電極材料と基板との電気的接触を確保しながら、ｐｎ接合等の半導体層の境界への電極材料の侵入が抑制されることから、オーミックコンタクトの確保が容易になり、且つ導電性が高められるので、電気特性が向上するものと考えられる。また、ファイヤースルーの制御が容易になるため、受光面側の半導体層の薄層化にも対応できる。Te量は35(mol%)未満ではAg溶解量の増大作用が十分に得られず、83(mol%)を越えると浸食抑制作用が強くなり過ぎてファイヤースルーが不十分になる。 Of the lead-free glass components, Te acts as a network-forming component, and as described above, the amount of Ag dissolved in the glass is increased to reduce the contact resistance and to reduce the Ag during firing. While suppressing the precipitation to widen the appropriate firing condition range, it has the effect of suppressing the erosion of the semiconductor substrate. Because of these effects, the insulating material is sufficiently eroded to ensure electrical contact between the electrode material and the substrate, and the electrode material can be prevented from entering the boundary of the semiconductor layer such as a pn junction. It is considered that the electrical characteristics are improved because it is easy to secure the conductivity and the conductivity is increased. In addition, since control of fire-through becomes easy, it is possible to cope with the thinning of the semiconductor layer on the light receiving surface side. If the amount of Te is less than 35 (mol%), the effect of increasing the amount of dissolved Ag cannot be obtained sufficiently. If the amount of Te exceeds 83 (mol%), the erosion inhibiting action becomes too strong and fire-through is insufficient.

また、Biは、ガラスの軟化点を上昇させる成分で、Teガラスの低粘性を保ったまま軟化点を調整するために添加される。また、ガラスに浸食作用を与える役割も果たす。前述したようにTeは浸食抑制作用が強いが、Bi量等を適宜調整することで適度な浸食性を得ることができる。Bi量は0.1(mol%)未満では軟化点が低くなり過ぎ、20(mol%)を越えるとガラスが結晶化し易くなる。 Bi is a component that raises the softening point of the glass and is added to adjust the softening point while maintaining the low viscosity of the Te glass. It also plays a role of giving erosion action to glass. As described above, Te has a strong anti-erosion effect, but moderate erosion can be obtained by appropriately adjusting the Bi amount and the like. If the amount of Bi is less than 0.1 (mol%), the softening point becomes too low, and if it exceeds 20 (mol%), the glass tends to crystallize.

また、Liは、ガラスの軟化点を低下させる作用を有するものであるが、ドナー成分でもあり、ｎ型半導体に対しては、半導体基板(例えばシリコン基板)と電極材料との相互拡散によって生ずる界面近傍におけるドナー濃度の低下を補償する作用を有する。Li量はWを必須としない場合には15.5(mol%)未満、Wを必須とする場合には10(mol%)未満ではドナー補償作用が十分に得られず、30(mol%)を越えると浸食作用が強くなり過ぎ、ガラスの安定性も低下する。なお、一般にアルカリ金属成分は太陽電池特性に悪影響を及ぼすため避けることが好ましいもので、例えば、Naは開放電圧Vocを低下させ、KはＦＦ値を低下させると共に接触抵抗Rcを上昇させる。しかも、これらNa、Kはドナーとはならないため含ませることの利点がない。これらに対して、Liはドナー補償作用があるため、ｎ型半導体への電極形成においては、高い太陽電池特性を得るために有用である。 Li, which has an action of lowering the softening point of glass, is also a donor component, and for an n-type semiconductor, an interface formed by mutual diffusion between a semiconductor substrate (for example, a silicon substrate) and an electrode material. It has an effect of compensating for a decrease in donor concentration in the vicinity. The amount of Li is less than 15.5 (mol%) if W is not essential, and if it is less than 10 (mol%) when W is essential, sufficient donor compensation cannot be obtained, and exceeds 30 (mol%). And the erosion action becomes too strong, and the stability of the glass also decreases. In general, alkali metal components are preferably avoided because they adversely affect solar cell characteristics. For example, Na decreases the open circuit voltage Voc, and K decreases the FF value and increases the contact resistance Rc. In addition, these Na and K do not become donors, so there is no advantage of including them. On the other hand, since Li has a donor compensation action, it is useful for obtaining high solar cell characteristics in forming an electrode on an n-type semiconductor.

また、Znは、ガラスを安定化させる成分であり、Teとのガラス化範囲が広いことから、ガラス中に含み得るTe量の範囲が広くなる利点がある。Znを含まない組成では結晶化し易くなり、延いては流動性が低下して基板との界面にガラスが行き渡りにくくなる。また、Znを含むことにより、基板上に電極を形成する際の接着強度が高められる利点もある。Zn量は0.1(mol%)未満では、ガラスの安定性が不十分になり、40(mol%)を越えると、却って結晶化し易くなり、安定性が不十分になる。 Further, Zn is a component that stabilizes the glass, and since the vitrification range with Te is wide, there is an advantage that the range of the amount of Te that can be included in the glass is widened. A composition containing no Zn is likely to be crystallized, and as a result, the fluidity is lowered, making it difficult for the glass to reach the interface with the substrate. In addition, the inclusion of Zn has an advantage that the adhesive strength when forming the electrode on the substrate can be increased. If the Zn content is less than 0.1 (mol%), the stability of the glass will be insufficient, and if it exceeds 40 (mol%), it will be easier to crystallize and the stability will be insufficient.

なお、前記第１発明においては、前記無鉛ガラスの成分のうち、Mg、Ti、V、Cr、Mn、Fe、Co、Ni、Cu、Wは、任意成分であり、軟化点、粘性、電気特性等の微調整の目的で、合計5(mol%)を上限として含まれ得るものであるが、何れも全く含まれていなくとも差し支えない。すなわち、前記無鉛ガラスは、Te、Bi、Li、Znのみから成るものや、これらに加えて特性に影響を与えない微量の不純物が含まれるものであってもよい。 In the first invention, among the components of the lead-free glass, Mg, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and W are optional components, and softening point, viscosity, and electrical characteristics. For the purpose of fine adjustment, etc., a total of 5 (mol%) can be included as an upper limit, but none of them may be included. That is, the lead-free glass may be made of only Te, Bi, Li, or Zn, or may contain a small amount of impurities that do not affect the characteristics in addition to these.

また、前記第２発明においては、前記無鉛ガラスの成分のうち、Wは必須成分である。Wはガラスを安定化させる成分であり、Teとのガラス化範囲が広いことから、Wが含まれているとガラス中に含み得るTe量の範囲が広くなる利点がある。但し、W量が多くなると軟化点が高くなるため、10(mol%)以下に留める必要がある。また、Mg、Ti、V、Cr、Mn、Fe、Co、Ni、Cuは、任意成分であり、軟化点、粘性、電気特性等の微調整の目的で、合計5(mol%)を上限として含まれ得るものであるが、何れも全く含まれていなくとも差し支えない。すなわち、前記無鉛ガラスは、Te、Bi、Li、Zn、Wのみから成るものや、これらに加えて特性に影響を与えない微量の不純物が含まれるものであってもよい。 Moreover, in the said 2nd invention, W is an essential component among the components of the said lead-free glass. W is a component that stabilizes glass, and since the vitrification range with Te is wide, when W is contained, there is an advantage that the range of the amount of Te that can be contained in the glass is widened. However, since the softening point increases as the amount of W increases, it is necessary to keep it at 10 (mol%) or less. In addition, Mg, Ti, V, Cr, Mn, Fe, Co, Ni, Cu are optional components, and for the purpose of fine adjustment of softening point, viscosity, electrical characteristics, etc., a total of 5 (mol%) is the upper limit. Although it can be included, it does not matter if none is included. That is, the lead-free glass may be composed of only Te, Bi, Li, Zn, W, or may contain a small amount of impurities that do not affect the characteristics in addition to these.

第１発明、第２発明の太陽電池電極用ペーストおよび第３発明の太陽電池セルは、このような性質・作用を有するTe、Bi、Li、Znの４つの元素をガラスの主成分として、その割合を第１発明においては合計95(mol%)以上、第２発明においては合計90(mol%)以上、且つ、それぞれを上述した範囲で適宜調整すると共に、第２発明においては、これに加えてWを必須成分として0.4〜10(mol%)の範囲で含むことで、接触抵抗の低減、導電性の向上、浸食性の制御、およびガラスの安定化、更に、ｎ型半導体に対してはドナー濃度の確保等を実現したものである。この構成によれば、ガラスの主成分がTe、Bi、Li、Znの４種に絞られていることから、浸食性制御に優れたPbをガラス中或いはペースト中に含まなくとも、高い太陽電池特性が容易に得られる。ガラスにおいては、構成成分の種類が多い方が高い安定性が得られるが、構成成分の種類が少ない方が太陽電池特性は低下し難い。本発明者等は、この観点からガラス組成を改めて検討した結果、Te、Bi、Li、Znの４成分が好ましく、これらが合計で、Wを必須としない場合には95(mol%)以上、Wを必須とする場合には90(mol%)以上の割合で含まれるガラス組成において、特に高い太陽電池特性が得られることを見出して、第１発明乃至第３発明を完成させたものである。４成分の各々の割合は、前述した範囲内で要求特性に応じて適宜変更されるもので、特に限定されず、幅広い範囲で組成を定め得る。 The paste for solar battery electrode of the first invention, the second invention and the solar battery cell of the third invention have four elements of Te, Bi, Li and Zn having such properties and actions as the main components of glass. The ratio is 95 (mol%) or more in the first invention, 90 (mol%) or more in the second invention, and each is adjusted as appropriate within the above-mentioned range. Incorporating W as an essential component in the range of 0.4 to 10 (mol%) reduces contact resistance, improves conductivity, controls erosion, stabilizes glass, and for n-type semiconductors This ensures the donor concentration. According to this configuration, the main components of the glass are limited to four types of Te, Bi, Li, and Zn, so that a high solar cell can be obtained even if Pb excellent in erosion control is not contained in the glass or paste. Characteristics are easily obtained. In glass, higher stability is obtained when there are more types of components, but solar cell characteristics are less likely to decrease when there are fewer types of components. As a result of reconsidering the glass composition from this point of view, the present inventors preferred four components of Te, Bi, Li, and Zn, and when these are total and W is not essential, 95 (mol%) or more, When W is essential, it has been found that particularly high solar cell characteristics can be obtained in a glass composition contained in a proportion of 90 (mol%) or more, and the first to third inventions have been completed. . The ratio of each of the four components is appropriately changed in accordance with the required characteristics within the above-described range, and is not particularly limited, and the composition can be determined in a wide range.

なお、前記無鉛ガラスの構成成分として明示した成分以外のものは、ガラス特性に実質的に影響を及ぼさない範囲で少量含むことができる。 In addition, components other than those specified as the constituent components of the lead-free glass can be contained in a small amount within a range that does not substantially affect the glass characteristics.

また、前記無鉛ガラスは、Bを実質的に含まないことが好ましい。Bはアクセプタとして作用するため、ｎ層上への電極形成に用いると変換効率が低下する。なお、「実質的に含まない」とは、理想的にはこれらを全く含まないことを意味するが、これに限られず、特性に影響しないような微量を含むものを排除しない。例えば、3.0(mol%)以下の範囲で含まれていても差し支えない。 Moreover, it is preferable that the said lead-free glass does not contain B substantially. Since B acts as an acceptor, the conversion efficiency decreases when it is used to form an electrode on the n layer. Note that “substantially free” means that these are not included at all ideally, but is not limited to this, and does not exclude those containing a minute amount that does not affect the characteristics. For example, it may be contained within a range of 3.0 (mol%) or less.

また、第１発明、第２発明の太陽電池電極用ペーストから生成した電極は、安定したオーミック抵抗性を有するので、シート抵抗の低い基板はもちろん、80〜120(Ω/□)程度の高シート抵抗基板、例えばＬＤＥ基板に対しても十分に低い接触抵抗が得られる。そのため、ｐｎ接合等の半導体層境界に電極材料が侵入しないようにファイヤースルー等の条件を制御することにより、リーク電流が低く(すなわち並列抵抗Rshが高く)なり、曲線因子ＦＦが低下せず、電流値が大きく、且つ光電変換率の高い太陽電池を得ることができる。 In addition, since the electrodes produced from the solar cell electrode pastes of the first and second inventions have stable ohmic resistance, not only substrates with low sheet resistance but also high sheets of about 80 to 120 (Ω / □) A sufficiently low contact resistance can be obtained even for a resistance substrate, for example an LDE substrate. Therefore, by controlling the conditions such as fire-through so that the electrode material does not enter the semiconductor layer boundary such as a pn junction, the leakage current is low (that is, the parallel resistance Rsh is high), the fill factor FF is not reduced, A solar cell having a large current value and a high photoelectric conversion rate can be obtained.

また、好適には、前記導電性粉末は、Ag粉末である。本発明が適用される電極用ペーストに含まれる導電性粉末は特に限定されず、Au,Ag,Cu,Al等が挙げられる。この中でも、AgはTeが存在することによる溶解量増大効果が顕著に得られるため、本発明の適用対象として特に好ましい。 Preferably, the conductive powder is an Ag powder. The conductive powder contained in the electrode paste to which the present invention is applied is not particularly limited, and examples thereof include Au, Ag, Cu, and Al. Among these, Ag is particularly preferable as an application target of the present invention because the effect of increasing the dissolution amount due to the presence of Te is remarkably obtained.

また、好適には、前記ガラスフリットは平均粒径(D50)が0.3〜10(μm)の範囲内である。ガラスフリットの平均粒径が小さすぎると、電極の焼成時に融解が早くなるため十分な電気的特性を得ることが困難になる。平均粒径が0.3(μm)以上であれば、このような問題が生じ難く、しかも、凝集が生じ難いのでペースト調製時に一層良好な分散性が得られる。また、ガラスフリットの平均粒径が導電性粉末の平均粒径よりも著しく大きい場合にも粉末全体の分散性が低下するが、10(μm)以下であれば一層良好な分散性が得られる。しかも、ガラスの一層の溶融性が得られる。ガラスフリットの平均粒径は、0.3〜3.0(μm)の範囲が一層好ましい。 Preferably, the glass frit has an average particle diameter (D50) in the range of 0.3 to 10 (μm). If the average particle size of the glass frit is too small, it becomes difficult to obtain sufficient electrical characteristics because the melting is accelerated when the electrode is fired. When the average particle size is 0.3 (μm) or more, such a problem hardly occurs, and further, agglomeration hardly occurs, so that better dispersibility can be obtained at the time of preparing the paste. Also, the dispersibility of the whole powder is lowered when the average particle size of the glass frit is significantly larger than the average particle size of the conductive powder, but better dispersibility can be obtained when it is 10 (μm) or less. Moreover, a further melting property of the glass can be obtained. The average particle size of the glass frit is more preferably in the range of 0.3 to 3.0 (μm).

なお、上記ガラスフリットの平均粒径は空気透過法による値である。空気透過法は、粉体層に対する流体(例えば空気)の透過性から粉体の比表面積を測定する方法をいう。この測定方法の基礎となるのは、粉体層を構成する全粒子の濡れ表面積とそこを通過する流体の流速および圧力降下の関係を示すコゼニー・カーマン(Kozeny-Carmann)の式であり、装置によって定められた条件で充填された粉体層に対する流速と圧力降下を測定して試料の比表面積を求める。この方法は充填された粉体粒子の間隙を細孔と見立てて、空気の流れに抵抗となる粒子群の濡れ表面積を求めるもので、通常はガス吸着法で求めた比表面積よりも小さな値を示す。求められた上記比表面積および粒子密度から粉体粒子を仮定した平均粒径を算出できる。 The average particle size of the glass frit is a value obtained by the air permeation method. The air permeation method is a method for measuring the specific surface area of a powder from the permeability of a fluid (for example, air) to a powder layer. The basis of this measurement method is the Kozeny-Carmann equation, which shows the relationship between the wetted surface area of all particles making up the powder layer and the flow velocity and pressure drop of the fluid passing therethrough. The specific surface area of the sample is obtained by measuring the flow velocity and pressure drop with respect to the powder layer filled under the conditions determined by the above. In this method, the gap between the filled powder particles is regarded as pores, and the wetted surface area of the particles that resists the flow of air is determined. Usually, the value is smaller than the specific surface area determined by the gas adsorption method. Show. An average particle diameter assuming powder particles can be calculated from the obtained specific surface area and particle density.

また、好適には、前記導電性粉末は平均粒径(D50)が0.3〜3.0(μm)の範囲内の銀粉末である。導電性粉末としては銅粉末やニッケル粉末等も用い得るが、銀粉末が高い導電性を得るために最も好ましい。また、銀粉末の平均粒径が3.0(μm)以下であれば一層良好な分散性が得られるので一層高い導電性が得られる。また、0.3(μm)以上であれば凝集が抑制されて一層良好な分散性が得られる。なお、0.3(μm)未満の銀粉末は著しく高価であるため、製造コストの面からも0.3(μm)以上が好ましい。また、導電性粉末、ガラスフリット共に平均粒径が3.0(μm)以下であれば、細線パターンで電極を印刷形成する場合にも目詰まりが生じ難い利点がある。 Preferably, the conductive powder is a silver powder having an average particle diameter (D50) in the range of 0.3 to 3.0 (μm). Although copper powder, nickel powder, etc. can be used as the conductive powder, silver powder is most preferable in order to obtain high conductivity. Further, if the average particle size of the silver powder is 3.0 (μm) or less, better dispersibility can be obtained, and thus higher conductivity can be obtained. Moreover, if it is 0.3 (μm) or more, aggregation is suppressed and better dispersibility can be obtained. Since silver powder of less than 0.3 (μm) is extremely expensive, 0.3 (μm) or more is preferable from the viewpoint of manufacturing cost. Further, if the average particle diameter of both the conductive powder and the glass frit is 3.0 (μm) or less, there is an advantage that clogging hardly occurs even when the electrode is printed by a fine line pattern.

なお、前記銀粉末は特に限定されず、球状や鱗片状等、どのような形状の粉末が用いられる場合にも導電性を保ったまま細線化が可能である。但し、球状粉を用いた場合が印刷性に優れると共に、塗布膜における銀粉末の充填率が高くなるため、導電性の高い銀が用いられることと相俟って、鱗片状等の他の形状の銀粉末が用いられる場合に比較して、その塗布膜から生成される電極の導電率が高くなる。そのため、必要な導電性を確保したまま線幅を一層細くすることが可能となることから、特に好ましい。 The silver powder is not particularly limited, and thinning can be performed while maintaining conductivity even when a powder of any shape such as a spherical shape or a scale shape is used. However, when the spherical powder is used, the printability is excellent and the filling rate of the silver powder in the coating film is increased, so that, together with the use of highly conductive silver, other shapes such as scales are used. Compared with the case where the silver powder of this is used, the electrical conductivity of the electrode produced | generated from the coating film becomes high. Therefore, it is particularly preferable because the line width can be further reduced while ensuring the necessary conductivity.

また、好適には、前記太陽電池電極用ペーストは、25(℃)−20(rpm)における粘度が150〜250(Pa・s)の範囲内、粘度比(すなわち、［10(rpm)における粘度］/［100(rpm)における粘度］)が3〜8である。このような粘度特性を有するペーストを用いることにより、スキージングの際に好適に低粘度化してスクリーンメッシュを透過し、その透過後には高粘度に戻って印刷幅の広がりが抑制されるので、スクリーンを容易に透過して目詰まりを生じないなど印刷性を保ったまま細線パターンが容易に得られる。電極ペーストの粘度は、160〜200(Pa・s)の範囲が一層好ましく、粘度比は3.2〜6.5の範囲が一層好ましい。 Preferably, the solar cell electrode paste has a viscosity ratio within a range of 150 to 250 (Pa · s) at 25 (° C.)-20 (rpm) (ie, a viscosity at [10 (rpm)). ] / [Viscosity at 100 (rpm)]) is 3-8. By using a paste having such a viscosity characteristic, the viscosity is suitably reduced during squeezing and transmitted through the screen mesh. After the transmission, the viscosity returns to a high viscosity and the expansion of the printing width is suppressed. Thus, a fine line pattern can be easily obtained while maintaining the printability such that clogging does not easily occur and clogging does not occur. The viscosity of the electrode paste is more preferably in the range of 160 to 200 (Pa · s), and the viscosity ratio is more preferably in the range of 3.2 to 6.5.

なお、線幅を細くしても断面積が保たれるように膜厚を厚くすることは、例えば、印刷製版の乳剤厚みを厚くすること、テンションを高くすること、線径を細くして開口径を広げること等でも可能である。しかしながら、乳剤厚みを厚くすると版離れが悪くなるので印刷パターン形状の安定性が得られなくなる。また、テンションを高くし或いは線径を細くすると、スクリーンメッシュが伸び易くなるので寸法・形状精度を保つことが困難になると共に印刷製版の耐久性が低下する問題がある。しかも、太幅で設けられることから膜厚を厚くすることが無用なバスバーも厚くなるため、材料の無駄が多くなる問題もある。 Note that increasing the film thickness so that the cross-sectional area can be maintained even if the line width is reduced includes, for example, increasing the emulsion thickness of the printing plate, increasing the tension, and reducing the line diameter. It is also possible to widen the aperture. However, when the emulsion thickness is increased, the separation of the plate is deteriorated, so that the stability of the printed pattern shape cannot be obtained. In addition, when the tension is increased or the wire diameter is reduced, the screen mesh is easily stretched, so that it is difficult to maintain the dimensional and shape accuracy and the durability of the printing plate making is lowered. In addition, since it is provided with a large width, a bus bar that is unnecessary to increase the film thickness is also increased, resulting in a problem of waste of material.

また、好適には、前記太陽電池電極用ペーストは、前記導電性粉末を64〜90重量部、前記ベヒクルを3〜20重量部の範囲内の割合で含むものである。このようにすれば、印刷性が良好で線幅の細く導電性の高い電極を容易に形成できる電極ペーストが得られる。 Preferably, the solar cell electrode paste includes the conductive powder in a proportion of 64 to 90 parts by weight and the vehicle in a proportion of 3 to 20 parts by weight. In this way, an electrode paste can be obtained that can easily form an electrode having good printability, thin line width, and high conductivity.

また、好適には、前記太陽電池電極用ペーストは、前記ガラスフリットを前記導電性粉末100重量部に対して0.1〜10重量部の範囲で含むものである。0.1重量部以上含まれていれば十分な浸食性(ファイヤスルー性)が得られるので、良好なオーミックコンタクトが得られる。また、10重量部以下に留められていれば絶縁層が形成され難いので十分な導電性が得られる。導電性粉末100重量部に対するガラス量は、0.5〜8重量部が一層好ましく、0.5〜7重量部が更に好ましい。 Preferably, the solar cell electrode paste includes the glass frit in a range of 0.1 to 10 parts by weight with respect to 100 parts by weight of the conductive powder. If it is contained in an amount of 0.1 part by weight or more, sufficient erosion property (fire-through property) can be obtained, so that a good ohmic contact can be obtained. Further, if it is kept at 10 parts by weight or less, it is difficult to form an insulating layer, and sufficient conductivity can be obtained. The glass amount relative to 100 parts by weight of the conductive powder is more preferably 0.5 to 8 parts by weight, and further preferably 0.5 to 7 parts by weight.

また、本発明の太陽電池電極用ペーストは、例えば、受光面電極の形成に好適に用いられるが、裏面電極においても、パッシベーション膜を設けてファイヤースルーによって形成する場合には好適に用いられる。例えば、ｐ型基板が用いられる場合においては、その表面に形成したｎ層上に受光面電極を設ける場合、裏面に形成したｐ⁺層上に裏面電極を設ける場合、ｎ型基板が用いられる場合においては、その表面に形成したｐ層上に受光面電極を設ける場合、裏面に形成したｎ⁺層上に裏面電極を設ける場合の何れの構成にも適用可能である。また、裏面側も受光面として機能させる両面受光型の太陽電池にも、もちろん適用可能である。 The solar cell electrode paste of the present invention is preferably used, for example, for the formation of a light-receiving surface electrode. However, the back electrode is also preferably used when a passivation film is provided and formed by fire-through. For example, when a p-type substrate is used, when a light receiving surface electrode is provided on an n layer formed on the surface thereof, when a back electrode is provided on a p ⁺ layer formed on the back surface, or when an n-type substrate is used. Can be applied to any configuration in which the light receiving surface electrode is provided on the p layer formed on the front surface and the back electrode is provided on the n ⁺ layer formed on the back surface. Of course, the present invention can also be applied to a double-sided light-receiving solar cell in which the back side functions as a light-receiving surface.

本発明の一実施例の電極用ペーストが受光面電極の形成に適用された太陽電池の断面構造を示す模式図である。It is a schematic diagram which shows the cross-sectional structure of the solar cell with which the paste for electrodes of one Example of this invention was applied for formation of a light-receiving surface electrode. 図１の太陽電池の受光面電極パターンの一例を示す図である。It is a figure which shows an example of the light-receiving surface electrode pattern of the solar cell of FIG. 本発明の一実施例の電極用ペーストが裏面電極の形成に適用された他の太陽電池の断面構造を示す模式図である。It is a schematic diagram which shows the cross-sectional structure of the other solar cell with which the paste for electrodes of one Example of this invention was applied for formation of a back surface electrode.

以下、本発明の一実施例を図面を参照して詳細に説明する。なお、以下の実施例において図は適宜簡略化或いは変形されており、各部の寸法比および形状等は必ずしも正確に描かれていない。 Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

図１は、本発明の一実施例の電極用ペーストが適用されたシリコン系太陽電池１０を備えた太陽電池モジュール１２の断面構造を模式的に示す図である。図１において、太陽電池モジュール１２は、上記太陽電池１０と、これを封止する封止材１４と、受光面側において封止材１４上に設けられた表面ガラス１６と、裏面側から太陽電池１０および封止材１４を保護するために設けられた保護フィルム(すなわちバックシート)１８とを備えている。上記封止材１４は、例えば、ＥＶＡから成るもので、十分な耐候性を有するように、架橋剤、紫外線吸収剤、接着保護剤等が適宜配合されている。また、上記保護フィルム１８は、例えば弗素樹脂やポリエチレンテレフタレート(ＰＥＴ)樹脂、或いはＰＥＴやＥＶＡ等から成る樹脂フィルムを複数枚貼り合わせたもの等から成るもので、高い耐候性や水蒸気バリア性等を備えている。 FIG. 1 is a diagram schematically showing a cross-sectional structure of a solar cell module 12 including a silicon-based solar cell 10 to which an electrode paste according to an embodiment of the present invention is applied. In FIG. 1, the solar cell module 12 includes the solar cell 10, a sealing material 14 for sealing the solar cell 10, a surface glass 16 provided on the sealing material 14 on the light receiving surface side, and a solar cell from the back surface side. 10 and a protective film (that is, a back sheet) 18 provided to protect the sealing material 14. The sealing material 14 is made of, for example, EVA, and is appropriately blended with a crosslinking agent, an ultraviolet absorber, an adhesion protective agent and the like so as to have sufficient weather resistance. The protective film 18 is made of, for example, fluorine resin, polyethylene terephthalate (PET) resin, or a laminate of a plurality of resin films made of PET, EVA, etc., and has high weather resistance, water vapor barrier properties, etc. I have.

また、上記の太陽電池１０は、例えばｐ型多結晶半導体であるシリコン基板２０と、その上下面にそれぞれ形成されたｎ層２２およびｐ⁺層２４と、そのｎ層２２上に形成された反射防止膜２６および受光面電極２８と、そのｐ⁺層２４上に形成された裏面電極３０とを備えている。上記シリコン基板２０の厚さ寸法は例えば100〜200(μm)程度である。 The solar cell 10 includes, for example, a silicon substrate 20 which is a p-type polycrystalline semiconductor, an n layer 22 and a p ⁺ layer 24 respectively formed on the upper and lower surfaces thereof, and a reflection formed on the n layer 22. A prevention film 26 and a light receiving surface electrode 28, and a back electrode 30 formed on the p ⁺ layer 24 are provided. The thickness dimension of the silicon substrate 20 is, for example, about 100 to 200 (μm).

上記のｎ層２２およびｐ⁺層２４は、シリコン基板２０の上下面に不純物濃度の高い層を形成することで設けられたもので、その高濃度層の厚さ寸法はｎ層２２が例えば70〜100(nm)程度、ｐ⁺層２４が例えば500(nm)程度である。ｎ層２２は、一般的なシリコン系太陽電池では100〜200(nm)程度であるが、本実施例ではそれよりも薄くされたＬＤＥ基板が用いられており、シャローエミッタと称される構造を成している。なお、ｎ層２２に含まれる不純物は、ｎ型のドーパント、例えば燐(P)で、ｐ⁺層２４に含まれる不純物は、ｐ型のドーパント、例えばアルミニウム(Al)や硼素(B)である。 The n layer 22 and the p ⁺ layer 24 are provided by forming layers having a high impurity concentration on the upper and lower surfaces of the silicon substrate 20, and the thickness dimension of the high concentration layer is, for example, 70 n. ˜100 (nm), and the p ⁺ layer 24 is about 500 (nm), for example. The n layer 22 is about 100 to 200 (nm) in a general silicon-based solar cell, but in this embodiment, an LDE substrate made thinner than that is used, and a structure called a shallow emitter is used. It is made. The impurity contained in the n layer 22 is an n-type dopant such as phosphorus (P), and the impurity contained in the p ⁺ layer 24 is a p-type dopant such as aluminum (Al) or boron (B). .

また、前記の反射防止膜２６は、例えば、窒化珪素 Si₃N₄等から成る薄膜で、例えば可視光波長の１／４程度の光学的厚さ、例えば80(nm)程度で設けられることによって10(％)以下、例えば2(％)程度の極めて低い反射率に構成されている。 The antireflection film 26 is a thin film made of, for example, silicon nitride Si ₃ N ₄ , and is provided with an optical thickness of, for example, about 1/4 of the visible light wavelength, for example, about 80 (nm). It is configured to have an extremely low reflectance of 10 (%) or less, for example, 2 (%).

また、前記の受光面電極２８は、例えば一様な厚さ寸法の厚膜導体から成るもので、図２に示されるように、受光面３２の略全面に、多数本の細線部を有する櫛状を成す平面形状で設けられている。 The light receiving surface electrode 28 is made of, for example, a thick film conductor having a uniform thickness. As shown in FIG. 2, the light receiving surface electrode 28 is a comb having a large number of thin line portions substantially on the entire surface of the light receiving surface 32. Are provided in a planar shape.

上記の厚膜導体は、Agおよびガラスを含む厚膜銀から成るもので、Ag 100重量部に対してガラスを0.1〜10重量部の範囲内、例えば2.2重量部程度の割合で含むものである。 The thick film conductor is made of thick film silver containing Ag and glass, and contains glass in a range of 0.1 to 10 parts by weight, for example, about 2.2 parts by weight with respect to 100 parts by weight of Ag.

また、前記ガラスは、例えば、Teがネットワークフォーマーとして働き、Pbを含まない無鉛テルルガラス、例えば、TeO₂-Bi₂O₃-Li₂O-ZnO系無鉛ガラスである。このガラスは、これら４成分を主成分として合計95(mol%)以上、且つ、これらを酸化物換算でそれぞれTeO₂ 35〜83(mol%)、Bi₂O₃ 0.1〜20(mol%)、Li₂O 15.5〜30(mol%)、ZnO 0.1〜40(mol%)の範囲内の割合で含む。この無鉛ガラスは、上記主成分の他に、Mg、Ti、V、Cr、Mn、Fe、Co、Ni、Cu、Wを合計5(mol%)以下の範囲で含むことができる。或いは、上記４成分をそれぞれTeO₂ 35〜83(mol%)、Bi₂O₃ 0.1〜20(mol%)、Li₂O 10〜30(mol%)、ZnO 0.1〜40(mol%)の範囲内で主成分として合計90(mol%)以上、WO₃を0.4〜10(mol%)の範囲で含む無鉛ガラスでもよい。この無鉛ガラスにも、Mg、Ti、V、Cr、Mn、Fe、Co、Ni、Cuを合計5(mol%)以下の範囲で含むことができる。なお、上記各無鉛ガラスは、Bを実質的に含まないものであるが、酸化物換算で3.0(mol%)までは許容される。 The glass is, for example, lead-free tellurium glass containing Te as a network former and containing no Pb, for example, TeO ₂ —Bi ₂ O ₃ —Li ₂ O—ZnO-based lead-free glass. This glass has a total of 95 (mol%) or more of these four components as main components, and these are TeO ₂ 35 to 83 (mol%), Bi ₂ O ₃ 0.1 to 20 (mol%) in terms of oxides, Li ₂ O 15.5 to 30 (mol%), ZnO 0.1 to 40 (mol%) in the ratio within the range. This lead-free glass can contain Mg, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and W in a total range of 5 (mol%) or less in addition to the main components. Alternatively, the above four components are in the range of TeO ₂ 35-83 (mol%), Bi ₂ O ₃ 0.1-20 (mol%), Li ₂ O 10-30 (mol%), ZnO 0.1-40 (mol%), respectively. Among them, lead-free glass containing 90 (mol%) or more in total as the main component and WO ₃ in the range of 0.4 to 10 (mol%) may be used. This lead-free glass can also contain Mg, Ti, V, Cr, Mn, Fe, Co, Ni, and Cu in a total range of 5 (mol%) or less. Each of the above lead-free glasses is substantially free of B, but is allowed up to 3.0 (mol%) in terms of oxide.

また、上記の導体層の厚さ寸法は例えば10〜25(μm)の範囲内、例えば15(μm)程度で、細線部の各々の幅寸法は例えば35〜80(μm)の範囲内、例えば45(μm)程度で、十分に高い導電性を備えている。 Further, the thickness dimension of the conductor layer is, for example, in the range of 10-25 (μm), for example, about 15 (μm), and the width dimension of each thin line portion is in the range of, for example, 35-80 (μm), for example, It has a sufficiently high conductivity of about 45 (μm).

また、前記の裏面電極３０は、ｐ⁺層２４上にアルミニウムを導体成分とする厚膜材料を略全面に塗布して形成された全面電極３４と、その全面電極３４上に帯状に塗布して形成された厚膜銀から成る帯状電極３６とから構成されている。この帯状電極３６は、裏面電極３０に半田リボン３８や導線等を半田付け可能にするために設けられたものである。前記受光面電極２８にも裏面側と同様に半田リボン３８が溶着されている。 The back electrode 30 is formed by applying a full-surface electrode 34 formed by applying a thick film material containing aluminum as a conductor component on the p ⁺ layer 24 over substantially the entire surface, and a strip-like application on the full-surface electrode 34. The band-shaped electrode 36 made of thick silver is formed. The strip electrode 36 is provided in order to make it possible to solder a solder ribbon 38 or a conductive wire to the back electrode 30. A solder ribbon 38 is welded to the light receiving surface electrode 28 in the same manner as the back surface side.

上記のような受光面電極２８は、例えば、導体粉末と、ガラスフリットと、ベヒクルと、溶剤とから成る電極用ペーストを用いて良く知られたファイヤースルー法によって形成されたものである。受光面電極形成を含む太陽電池１０の製造方法の一例を以下に説明する。 The light receiving surface electrode 28 as described above is formed, for example, by a well-known fire-through method using an electrode paste composed of conductive powder, glass frit, vehicle, and solvent. An example of a method for manufacturing the solar cell 10 including formation of the light receiving surface electrode will be described below.

まず、上記ガラスフリットを作製する。Te源としてTeO₂を、Bi源としてBi₂O₃を、Li源としてLi₂CO₃を、Zn源としてZnOをそれぞれ用意し、所望するガラス組成になるように秤量して調合する。これらに加えてMg、Ti、V、Cr、Mn、Fe、Co、Ni、Cu、W、Bを含む組成とする場合には、Mg源としてMgO、Ti源としてTiO₂、V源としてV₂O₅、Cr源としてCr₂O₃、Mn源としてMnO₂、Fe源としてFe₂O₃、Co源としてCo₃O₄、Ni源としてNiO、Cu源としてCuO、W源としてWO₃、B源としてH₃BO₃を、それぞれ用いる。これらを坩堝に投入して組成に応じた900〜1200(℃)の範囲内の温度で、30分〜1時間程度溶融し、急冷することでガラス化させる。このガラスを遊星ミルやボールミル等の適宜の粉砕装置を用いて粉砕する。粉砕時間は1〜8時間程度、粉砕後の平均粒径(D50)は例えば0.3〜3(μm)程度である。なお、上記ガラス粉末の平均粒径は空気透過法を用いて算出したものである。 First, the glass frit is produced. TeO ₂ is prepared as a Te source, Bi ₂ O ₃ is prepared as a Bi source, Li ₂ CO ₃ is prepared as a Li source, and ZnO is prepared as a Zn source, and they are weighed and prepared to have a desired glass composition. Mg in addition to these, Ti, when V, Cr, Mn, Fe, Co, Ni, Cu, W, a composition containing B is, V ₂ as TiO _2, V source MgO, as Ti source as a source of Mg O ₅ , Cr ₂ O ₃ as Cr source, MnO ₂ as Mn source, Fe ₂ O ₃ as Fe source, Co ₃ O ₄ as Co source, NiO as Ni source, CuO as Cu source, WO ₃ as B source, B H ₃ BO ₃ is used as a source. These are put into a crucible, melted at a temperature in the range of 900 to 1200 (° C.) according to the composition for about 30 minutes to 1 hour, and rapidly cooled to be vitrified. This glass is pulverized using an appropriate pulverizing apparatus such as a planetary mill or a ball mill. The pulverization time is about 1 to 8 hours, and the average particle size (D50) after pulverization is about 0.3 to 3 (μm), for example. In addition, the average particle diameter of the said glass powder is computed using the air permeation method.

また、導体粉末として、例えば、平均粒径(D50)が0.3〜3.0(μm)の範囲内、例えば平均粒径が2(μm)程度の市販の球状の銀粉末を用意する。このような平均粒径が十分に小さい銀粉末を用いることにより、塗布膜における銀粉末の充填率を高め延いては導体の導電率を高めることができる。また、前記ベヒクルは、有機溶剤に有機結合剤を溶解させて調製したもので、有機溶剤としては、例えばブチルカルビトールアセテートが、有機結合剤としては、例えばエチルセルロースが用いられる。ベヒクル中のエチルセルロースの割合は例えば15(wt%)程度である。また、ベヒクルとは別に添加する溶剤は、例えばブチルカルビトールアセテートである。すなわち、これに限定されるものではないが、ベヒクルに用いたものと同じ溶剤でよい。この溶剤は、ペーストの粘度調整の目的で添加される。 As the conductor powder, for example, a commercially available spherical silver powder having an average particle size (D50) in the range of 0.3 to 3.0 (μm), for example, an average particle size of about 2 (μm) is prepared. By using such silver powder having a sufficiently small average particle diameter, the filling rate of the silver powder in the coating film can be increased and the electrical conductivity of the conductor can be increased. The vehicle is prepared by dissolving an organic binder in an organic solvent. For example, butyl carbitol acetate is used as the organic solvent, and ethyl cellulose is used as the organic binder. The ratio of ethyl cellulose in the vehicle is, for example, about 15 (wt%). A solvent added separately from the vehicle is, for example, butyl carbitol acetate. That is, although it is not limited to this, the same solvent as that used for the vehicle may be used. This solvent is added for the purpose of adjusting the viscosity of the paste.

以上のペースト原料をそれぞれ用意して、例えば導体粉末を77〜90(wt%)の範囲内、例えば89(wt%)、ガラスフリットを0.1〜10(wt%)の範囲内、例えば2(wt%)、ベヒクルを3〜14(wt%)の範囲内、例えば6(wt%)、溶剤を2〜5(wt%)の範囲内、例えば3(wt%)の割合で秤量し、攪拌機等を用いて混合した後、例えば三本ロールミルで分散処理を行う。これにより、前記電極用ペーストが得られる。 Prepare the above paste raw materials, for example, conductor powder in the range of 77 to 90 (wt%), for example 89 (wt%), glass frit in the range of 0.1 to 10 (wt%), for example 2 (wt %), The vehicle is weighed in the range of 3 to 14 (wt%), for example, 6 (wt%), the solvent is in the range of 2 to 5 (wt%), for example, 3 (wt%), and the stirrer etc. Then, for example, a dispersion treatment is performed with a three-roll mill. Thereby, the electrode paste is obtained.

上記のようにして電極用ペーストを調製する一方、適宜のシリコン基板に例えば、熱拡散法やイオンプランテーション等の良く知られた方法で不純物を拡散し或いは注入して前記ｎ層２２およびｐ⁺層２４を形成することにより、前記シリコン基板２０を作製する。次いで、これに例えばＰＥ−ＣＶＤ(プラズマＣＶＤ)等の適宜の方法で窒化珪素薄膜を形成し、前記反射防止膜２６を設ける。 While preparing the electrode paste as described above, the n layer 22 and the p ⁺ layer are diffused or implanted into an appropriate silicon substrate by a well-known method such as a thermal diffusion method or ion plantation. By forming 24, the silicon substrate 20 is produced. Next, a silicon nitride thin film is formed thereon by an appropriate method such as PE-CVD (plasma CVD), and the antireflection film 26 is provided.

次いで、上記の反射防止膜２６上に前記図２に示すパターンで前記電極用ペーストをスクリーン印刷する。これを例えば150(℃)で乾燥し、更に、近赤外炉において700〜900(℃)の範囲内の温度で焼成処理を施す。これにより、その焼成過程で電極用ペースト中のガラス成分が反射防止膜２６を溶かし、その電極用ペーストが反射防止膜２６を破るので、電極用ペースト中の導体成分すなわち銀とｎ層２２との電気的接続が得られ、前記図１に示されるようにシリコン基板２０と受光面電極２８とのオーミックコンタクトが得られる。受光面電極２８は、このようにして形成される。 Next, the electrode paste is screen-printed on the antireflection film 26 with the pattern shown in FIG. This is dried at, for example, 150 (° C.), and further subjected to a baking treatment at a temperature in the range of 700 to 900 (° C.) in a near infrared furnace. As a result, the glass component in the electrode paste melts the antireflection film 26 in the firing process, and the electrode paste breaks the antireflection film 26. Therefore, the conductor component in the electrode paste, that is, silver and the n layer 22 Electrical connection is obtained, and an ohmic contact between the silicon substrate 20 and the light-receiving surface electrode 28 is obtained as shown in FIG. The light receiving surface electrode 28 is formed in this way.

なお、前記裏面電極３０は、上記工程の後に形成してもよいが、受光面電極２８と同時に焼成して形成することもできる。裏面電極３０を形成するに際しては、上記シリコン基板２０の裏面全面に、例えばアルミニウムペーストをスクリーン印刷法等で塗布し、焼成処理を施すことによってアルミニウム厚膜から成る前記全面電極３４を形成する。更に、その全面電極３４の表面に前記電極用ペーストをスクリーン印刷法等を用いて帯状に塗布して焼成処理を施すことによって、前記帯状電極３６を形成する。これにより、裏面全面を覆う全面電極３４と、その表面の一部に帯状に設けられた帯状電極３６とから成る裏面電極３０が形成され、前記の太陽電池１０が得られる。上記工程において、同時焼成で製造する場合には、受光面電極２８の焼成前に印刷処理を施すことになる。 The back electrode 30 may be formed after the above process, but may be formed by firing at the same time as the light receiving surface electrode 28. When the back electrode 30 is formed, the full surface electrode 34 made of a thick aluminum film is formed on the entire back surface of the silicon substrate 20 by, for example, applying an aluminum paste by screen printing or the like and performing a baking process. Further, the strip electrode 36 is formed by applying the electrode paste on the surface of the entire surface electrode 34 in a strip shape by screen printing or the like and performing a baking treatment. Thereby, the back electrode 30 which consists of the full surface electrode 34 which covers the whole back surface, and the strip | belt-shaped electrode 36 provided in strip shape on a part of the surface is formed, and the said solar cell 10 is obtained. In the above process, when manufacturing by simultaneous firing, a printing process is performed before firing the light-receiving surface electrode 28.

本実施例の太陽電池１０は、上述したように受光面電極２８がファイヤースルー法で設けられているが、その受光面電極２８が、前記組成の無鉛テルルガラスを含む厚膜銀ペーストを用いてファイヤースルーによって形成されていることから、ガラス中のTeの存在によってガラス中へのAg溶解量が増大すると共に、これに加えてガラス中に含まれるBi、Li、Znによって適度な浸食性や安定性等が得られることから、好適にオーミックコンタクトが得られ、電気的特性に優れ、しかも、接着強度の高い太陽電池１０が得られる。 In the solar cell 10 of this example, the light-receiving surface electrode 28 is provided by the fire-through method as described above, and the light-receiving surface electrode 28 uses a thick film silver paste containing lead-free tellurium glass having the above composition. Since it is formed by fire-through, the amount of Ag dissolved in the glass increases due to the presence of Te in the glass, and in addition to this, Bi, Li, and Zn contained in the glass cause moderate erosion and stability. Therefore, the ohmic contact can be suitably obtained, and the solar cell 10 having excellent electrical characteristics and high adhesive strength can be obtained.

図３は、本発明の一実施例の電極用ペーストが適用された他の実施例の太陽電池４０の断面構造を模式的に示す図である。太陽電池４０も前記太陽電池１０と同様に前記図１に示される封止材１４等で封止された状態で用いられるが、この図３においては省略した。図３において、太陽電池４０は、例えばｎ型多結晶半導体であるシリコン基板４２と、その上下面にそれぞれ形成されたｐ層４４およびｎ⁺層４６と、そのｐ層４４上に形成された反射防止膜４８および受光面電極５０と、そのｎ⁺層４６上に形成されたパッシベーション膜５２および裏面電極５４とを備えている。 FIG. 3 is a diagram schematically showing a cross-sectional structure of a solar cell 40 of another embodiment to which the electrode paste of one embodiment of the present invention is applied. The solar cell 40 is also used in a state of being sealed with the sealing material 14 shown in FIG. 1 as in the case of the solar cell 10, but is omitted in FIG. In FIG. 3, a solar cell 40 includes a silicon substrate 42 that is, for example, an n-type polycrystalline semiconductor, a p layer 44 and an n ⁺ layer 46 formed on the upper and lower surfaces thereof, and a reflection formed on the p layer 44. A prevention film 48 and a light-receiving surface electrode 50, and a passivation film 52 and a back electrode 54 formed on the n ⁺ layer 46 are provided.

上記のｐ層４４およびｎ⁺層４６は、シリコン基板４２の上下面に不純物濃度の高い層を形成することで設けられたもので、ｐ層４４に含まれる不純物は、ｐ型のドーパント、例えばアルミニウム(Al)や硼素(B)で、ｎ⁺層４６に含まれる不純物は、ｎ型のドーパント、例えば燐(P)である。また、前記の反射防止膜４８は、例えば、SiO₂から成る薄い第１層５６およびSi₃N₄等から成る第２層５８が積層されたものである。なお、ｐ層４４は、シリコン基板４２の一面にテクスチャ加工が施された後にドーパントを拡散して形成されており、反射防止膜４８はその表面形状に倣った凹凸面に形成されている。このテクスチャ加工は必ずしも施されていなくともよく、また、前記図１に示す太陽電池１０においても、このようなテクスチャ加工が施されていてもよい。また、前記のパッシベーション膜５２は、上記第２層５８と同様にSi₃N₄等から成るものである。この太陽電池４０は、ｐ層４４側に加えてｎ⁺層４６側からも受光する形式の両面受光型である。 The p layer 44 and the n ⁺ layer 46 are provided by forming layers having a high impurity concentration on the upper and lower surfaces of the silicon substrate 42. Impurities contained in the p layer 44 include p-type dopants, for example, An impurity contained in the n ⁺ layer 46 such as aluminum (Al) or boron (B) is an n-type dopant, for example, phosphorus (P). The antireflection film 48 is formed by laminating a thin first layer 56 made of SiO ₂ and a second layer 58 made of Si ₃ N ₄ or the like, for example. The p layer 44 is formed by diffusing a dopant after texture processing is performed on one surface of the silicon substrate 42, and the antireflection film 48 is formed on an uneven surface following the surface shape. This texture processing does not necessarily have to be performed, and such a texture processing may also be performed in the solar cell 10 shown in FIG. The passivation film 52 is made of Si ₃ N ₄ or the like, similar to the second layer 58. This solar cell 40 is a double-sided light receiving type that receives light not only from the p layer 44 side but also from the n ⁺ layer 46 side.

また、前記受光面電極５０は、例えばAgを導体成分として含む電極ペースト或いはこれに更にAlを導体成分として含む電極ペーストから形成されたもので、前記受光面電極２８と同様にファイヤースルーによって反射防止膜４８を破って基板４２に電気的に接触させられている。また、前記裏面電極５４は、例えば、Agを導体成分として含むもので、前記受光面電極２８の形成に用いられたものと同様な電極ペーストを用いて、ファイヤースルーによってパッシベーション膜５２を破って基板４２に電気的に接触させられている。本発明の電極用ペーストは、このようなｎ型シリコン基板４２の裏面に形成されたｎ⁺層４６上に電極を形成する場合にも同様に適用される。 The light receiving surface electrode 50 is formed of, for example, an electrode paste containing Ag as a conductor component or an electrode paste further containing Al as a conductor component. The film 48 is broken and is in electrical contact with the substrate 42. The back electrode 54 includes, for example, Ag as a conductor component, and breaks the passivation film 52 by fire-through using an electrode paste similar to that used for forming the light-receiving surface electrode 28. 42 is in electrical contact. The electrode paste of the present invention is similarly applied when forming an electrode on the n ⁺ layer 46 formed on the back surface of the n-type silicon substrate 42.

以下、前記図１に示す太陽電池１０において、ガラス組成を種々変更して評価した結果を、ガラス組成および評価結果をまとめた下記の表１〜表４を参照して説明する。この評価では、TeO₂-Bi₂O₃-Li₂O-ZnO系ガラスを用い、主成分であるTe、Bi、Li、Znの割合を種々変更すると共に、追加のガラス成分(副成分)としてMgO、TiO₂、V₂O₅、Cr₂O₃、MnO₂、Fe₂O₃、Co₃O₄、NiO、CuO、WO₃、B₂O₃のうちの１〜４種を含むものを評価した。また、何れの試料も、前述した製造工程に従ってガラスフリットを作製し、電極用ペーストを調製して、受光面電極２８を形成し、太陽電池１０を製造して、その出力を測定してＦＦ値を求めた。ペースト調製に際しては、印刷性を同等とするために、25(℃)−20(rpm)における粘度が180〜200(Pa・s)になるように調整し、印刷製版はSUS400製、線径18(μm)のメッシュで乳剤厚を15(μm)とした。また、Ag粉末は平均粒径2(μm)の球状粉を用い、グリッドラインの幅寸法が45(μm)になるように印刷条件を設定した。また、基板はシート抵抗110±10(Ω/sq)のものを用いた。また、太陽電池の出力は市販のソーラーシミュレータを用いて測定して得られたＦＦ値に基づいて評価した。表１〜表４には、それぞれＦＦ値とその値に基づいて判定した評価結果とを、ＦＦ値75以上を「○」(すなわち実施例)、75未満を「×」(すなわち比較例)として示した。ＦＦ値は良好なオーミックコンタクトが得られているか否かの判定であり、一般に、太陽電池はＦＦ値が70以上であれば使用可能とされているが、高いほど好ましいのはもちろんであり、本実施例においては、ＦＦ値が75以上を合格とした。また、特にデータは示さないが、受光面電極２８に半田リボンを接着して市販の引張試験機で基板２０と電極２８との接着強度を評価したところ、全ての試料で実用上十分な強度を有することを確認した。なお、表において、「主成分合計」は、主成分TeO₂、Bi₂O₃、Li₂O、ZnOの合計量である。 Hereinafter, in the solar cell 10 shown in the said FIG. 1, the result evaluated by changing various glass compositions is demonstrated with reference to the following Table 1-Table 4 which put together the glass composition and the evaluation result. In this evaluation, using a _{_{_{_{TeO 2 -Bi 2 O 3 -Li 2}}}} O-ZnO -based glass, Te as the main component, Bi, Li, while variously changing the ratio of Zn, as an additional glass component (subcomponent) _{_{MgO, TiO 2, V 2 O}} 5, Cr 2 O 3, MnO 2, Fe 2 O 3, Co 3 O 4, NiO, CuO, those containing 1-4 kind of WO _{_3,} B ₂ O ₃ evaluated. In addition, for each sample, a glass frit is prepared according to the manufacturing process described above, an electrode paste is prepared, a light-receiving surface electrode 28 is formed, a solar cell 10 is manufactured, and its output is measured to obtain an FF value. Asked. In preparing the paste, in order to equalize the printability, the viscosity at 25 (° C.)-20 (rpm) is adjusted to be 180 to 200 (Pa · s), the printing plate is made of SUS400, the wire diameter is 18 The emulsion thickness was 15 (μm) with a (μm) mesh. The Ag powder was a spherical powder having an average particle size of 2 (μm), and the printing conditions were set so that the width of the grid line would be 45 (μm). A substrate having a sheet resistance of 110 ± 10 (Ω / sq) was used. Moreover, the output of the solar cell was evaluated based on the FF value obtained by measurement using a commercially available solar simulator. Tables 1 to 4 show the FF values and the evaluation results determined based on the FF values, with an FF value of 75 or more as “◯” (ie, an example) and less than 75 as “x” (ie, a comparative example). Indicated. The FF value is a determination as to whether or not a good ohmic contact is obtained. In general, a solar cell can be used if the FF value is 70 or more. In the examples, an FF value of 75 or more was considered acceptable. Although no particular data is shown, when a solder ribbon was bonded to the light-receiving surface electrode 28 and the adhesion strength between the substrate 20 and the electrode 28 was evaluated using a commercially available tensile tester, all samples had sufficient strength for practical use. Confirmed to have. In the table, “total main components” is the total amount of main components TeO ₂ , Bi ₂ O ₃ , Li ₂ O, and ZnO.

上記表１〜表４において、No.2〜8、No.11〜17、No.20〜25、No.28〜34、No.36〜65、No.67〜73、No.76、77、No.80〜84、No.87、88、No.91、92、No.94〜112が実施例、他が比較例である。 In Table 1 to Table 4, No. 2 to 8, No. 11 to 17, No. 20 to 25, No. 28 to 34, No. 36 to 65, No. 67 to 73, No. 76, 77, Nos. 80 to 84, Nos. 87 and 88, Nos. 91 and 92, and Nos. 94 to 112 are examples, and others are comparative examples.

表１に示すNo.1〜35は、TeO₂、Bi₂O₃、Li₂O、ZnOの４成分系で、各成分の適切な範囲を検討したものである。No.1〜9はTe量の範囲を検討したガラス組成である。TeO₂を33.0〜83.5(mol%)、Bi₂O₃を0.3〜19.0(mol%)、Li₂Oを16.0〜22.0(mol%)、ZnOを0.2〜26.0(mol%)、MgOを0〜3.0(mol%)の範囲内のガラス組成では、TeO₂量が35.0〜83.0(mol%)の範囲のNo.2〜8で、ＦＦ値が75〜78と良好な結果が得られた。特に、TeO₂を47.0〜61.0(mol%)、Bi₂O₃を3.5〜6.2(mol%)、Li₂Oを16.0〜21.2(mol%)、ZnOを16.0〜26.0(mol%)、MgOが0〜3.0(mol%)の組成では、ＦＦ値が77以上、TeO₂を57.0〜64.0(mol%)、Bi₂O₃を4.0〜6.2(mol%)、Li₂Oを16.0〜17.0(mol%)、ZnOを16.0〜19.8(mol%)の組成では、ＦＦ値が78の極めて良好な結果が得られた。これに対して、TeO₂量が33.0(mol%)のNo.1、83.5(mol%)のNo.9ではＦＦ値が74に留まった。 No.1~35 shown in Table 1 is a _{_{_{TeO 2, Bi 2 O 3,}}} Li 2 O, 4 -component system of ZnO, is obtained by considering the appropriate range for each component. Nos. 1 to 9 are glass compositions for which the range of Te amount was studied. TeO ₂ and 33.0~83.5 (mol%), the _{_{Bi 2 O 3 0.3~19.0 (mol%}} ), Li a _{2 O 16.0~22.0 (mol%),} ZnO a 0.2~26.0 (mol%), 0~ the MgO With glass compositions in the range of 3.0 (mol%), TeO ₂ content was No. ₂ to 8 in the range of 35.0 to 83.0 (mol%), and good results were obtained with FF values of 75 to 78. In particular, TeO ₂ is 47.0 to 61.0 (mol%), Bi ₂ O ₃ is 3.5 to 6.2 (mol%), Li ₂ O is 16.0 to 21.2 (mol%), ZnO is 16.0 to 26.0 (mol%), MgO is 0-3.0 the composition (mol%), FF value is 77 or more, a TeO ₂ 57.0~64.0 (mol%), the _{_{Bi 2 O 3 4.0~6.2 (mol%}} ), Li 2 O and 16.0-17.0 (mol %) And ZnO in the composition of 16.0 to 19.8 (mol%), an extremely good result with an FF value of 78 was obtained. On the other hand, the FF value stayed at 74 in No. 1 where the amount of TeO ₂ was 33.0 (mol%) and No. 9 where 83.5 (mol%).

また、No.10〜18はBi量の範囲を検討したガラス組成である。TeO₂を48.0〜70.0(mol%)、Bi₂O₃を0〜22.0(mol%)、Li₂Oを16.0〜21.3(mol%)、ZnOを12.0〜18.6(mol%)の範囲内のガラス組成では、Bi₂O₃量が0.1〜20.0(mol%)の範囲のNo.11〜17で、ＦＦ値が75〜78と良好な結果が得られた。特に、TeO₂を60.0〜65.5(mol%)、Bi₂O₃を2.5〜10.0(mol%)、Li₂Oを16.0〜18.0(mol%)、ZnOを12.0〜16.0(mol%)、MgOを0〜2.0(mol%)の組成では、ＦＦ値が77以上、TeO₂を62.0〜65.5(mol%)、Bi₂O₃を2.5〜4.0(mol%)、Li₂Oを16.0(mol%)、ZnOを16.0(mol%)、MgOを0〜2.0(mol%)の組成では、ＦＦ値が78の極めて良好な結果が得られた。これに対して、Bi₂O₃量が0(mol%)のNo.10、22.0(mol%)のNo.18ではＦＦ値が74に留まった。 Nos. 10 to 18 are glass compositions for which the range of Bi amount was examined. TeO ₂ 48.0-70.0 (mol%), Bi ₂ O ₃ 0-22.0 (mol%), Li ₂ O 16.0-21.3 (mol%), ZnO 12.0-18.6 (mol%) In terms of composition, No. 11 to 17 in the range of Bi ₂ O _{3 in} the range of 0.1 to 20.0 (mol%), and good results were obtained with an FF value of 75 to 78. In particular, TeO ₂ is 60.0-65.5 (mol%), Bi ₂ O ₃ is 2.5-10.0 (mol%), Li ₂ O is 16.0-18.0 (mol%), ZnO is 12.0-16.0 (mol%), MgO 0 to 2.0 in the composition of (mol%), FF value is 77 or more, a TeO ₂ 62.0~65.5 (mol%), the _{_{Bi 2 O 3 2.5~4.0 (mol%}} ), the Li ₂ O 16.0 (mol%) With a composition of ZnO of 16.0 (mol%) and MgO of 0 to 2.0 (mol%), a very good result with an FF value of 78 was obtained. On the other hand, the FF value stayed at 74 for No. 10 with a Bi ₂ O ₃ content of 0 (mol%) and No. 18 with 22.0 (mol%).

また、No.19〜26はLi量の範囲を検討したガラス組成である。TeO₂を52.0〜69.0(mol%)、Bi₂O₃を2.0〜6.0(mol%)、Li₂Oを15.0〜32.0(mol%)、ZnOを10.0〜14.2(mol%)の範囲内のガラス組成では、Li₂O量が15.5〜30.0(mol%)の範囲のNo.20〜25で、ＦＦ値が75〜77と良好な結果が得られた。特に、TeO₂を59.0〜64.0(mol%)、Bi₂O₃を6.0(mol%)、Li₂Oを20.0〜25.0(mol%)、ZnOを10.0(mol%)の組成では、ＦＦ値が77の極めて良好な結果が得られた。これに対して、Li₂O量が15.0(mol%)のNo.19、32.0(mol%)のNo.26ではＦＦ値が74に留まった。 Nos. 19 to 26 are glass compositions for which the range of Li amount was studied. TeO ₂ 52.0-69.0 (mol%) Bi ₂ O ₃ 2.0-6.0 (mol%) Li ₂ O 15.0-32.0 (mol%) ZnO 10.0-14.2 (mol%) With respect to the composition, No. 20 to 25 in the range of 15.5 to 30.0 (mol%) of Li ₂ O, and a good result with an FF value of 75 to 77 was obtained. In particular, the composition of TeO ₂ 59.0-64.0 (mol%), Bi ₂ O ₃ 6.0 (mol%), Li ₂ O 20.0-25.0 (mol%), ZnO 10.0 (mol%), the FF value is 77 very good results were obtained. In contrast, the FF value remained at 74 for No. 19 with a Li ₂ O content of 15.0 (mol%) and No. 26 with 32.0 (mol%).

また、No.27〜35はZn量の範囲を検討したガラス組成である。TeO₂を39.0〜80.0(mol%)、Bi₂O₃を3.0〜6.2(mol%)、Li₂Oを16.0〜21.4(mol%)、ZnOを0〜42.0(mol%)、MgOを0〜4.0(mol%)の範囲内のガラス組成では、ZnO量が0.1〜40.0(mol%)の範囲のNo.28〜34で、ＦＦ値が75〜78と良好な結果が得られた。特に、TeO₂を42.4〜61.0(mol%)、Bi₂O₃を3.0〜6.2(mol%)、Li₂Oを16.0〜21.4(mol%)、ZnOを16.0〜30.0(mol%)、MgOを0〜4.0(mol%)の組成では、ＦＦ値が77以上、TeO₂を54.0〜61.0(mol%)、Bi₂O₃を3.0〜4.5(mol%)、Li₂Oを16.0〜18.5(mol%)、ZnOを16.0〜23.0(mol%)、MgOを0〜4.0(mol%)の組成では、ＦＦ値が78の極めて良好な結果が得られた。これに対して、ZnO量が0(mol%)のNo.27ではＦＦ値が73に留まり、42.0(mol%)のNo.35ではＦＦ値が74に留まった。 Nos. 27 to 35 are glass compositions for which the range of Zn content was studied. TeO ₂ and 39.0~80.0 (mol%), the _{_{Bi 2 O 3 3.0~6.2 (mol%}} ), Li a _{2 O 16.0~21.4 (mol%),} ZnO and 0~42.0 (mol%), 0~ the MgO With a glass composition in the range of 4.0 (mol%), ZnO amount was No. 28 to 34 in the range of 0.1 to 40.0 (mol%), and a good result was obtained with an FF value of 75 to 78. In particular, TeO ₂ 42.4 to 61.0 (mol%), Bi ₂ O ₃ 3.0 to 6.2 (mol%), Li ₂ O 16.0 to 21.4 (mol%), ZnO 16.0 to 30.0 (mol%), MgO 0-4.0 the composition (mol%), FF value is 77 or more, a TeO ₂ 54.0~61.0 (mol%), the _{_{Bi 2 O 3 3.0~4.5 (mol%}} ), Li 2 O and 16.0-18.5 (mol %), ZnO 16.0 to 23.0 (mol%), and MgO 0 to 4.0 (mol%), an extremely good result with an FF value of 78 was obtained. In contrast, the FF value stayed at 73 for No. 27 with the ZnO content of 0 (mol%), and remained at 74 for No. 35 with 42.0 (mol%).

これらNo.1〜35の評価結果によれば、４成分系においては、TeO₂を35.0〜83.0(mol%)、Bi₂O₃を0.1〜20.0(mol%)、Li₂Oを15.5〜30.0(mol%)、ZnOを0.1〜40.0(mol%)の範囲内で良好な結果が得られ、特に、TeO₂を42.4〜65.5(mol%)、Bi₂O₃を2.5〜10.0(mol%)、Li₂Oを16.0〜25.0(mol%)、ZnOを10.0〜30.0(mol%)の範囲内で、ＦＦ値77以上、TeO₂を54.0〜65.5(mol%)、Bi₂O₃を2.5〜6.2(mol%)、Li₂Oを16.0〜18.5(mol%)、ZnOを16.0〜23.0(mol%)の範囲内で、ＦＦ値78の極めて良好な結果が得られる。 According to the evaluation results of these Nos. 1 to 35, in the four-component system, TeO ₂ is 35.0 to 83.0 (mol%), Bi ₂ O ₃ is 0.1 to 20.0 (mol%), Li ₂ O is 15.5 to 30.0. (mol%), good results within the range of the ZnO 0.1~40.0 (mol%) is obtained, in particular, a TeO ₂ 42.4~65.5 (mol%), the _{_{Bi 2 O 3 2.5~10.0 (mol%}} ) the _{Li 2 O 16.0~25.0 (mol%)} , the ZnO in the range of 10.0~30.0 (mol%), FF value 77 or more, a _{TeO 2 54.0~65.5 (mol%),} 2.5~ the Bi ₂ O ₃ In the range of 6.2 (mol%), Li ₂ O of 16.0 to 18.5 (mol%), and ZnO of 16.0 to 23.0 (mol%), extremely good results with an FF value of 78 are obtained.

また、表２において、No.36〜39は主成分４成分に加えてMgOを含むガラス組成を検討したものである。TeO₂を40.6〜66.5(mol%)、Bi₂O₃を4.2〜7.2(mol%)、Li₂Oを16.0〜21.4(mol%)、ZnOを12.0〜28.4(mol%)、MgOを0.2〜5.0(mol%)、TiO₂を0〜1.5(mol%)、主成分合計量を95.0〜99.8(mol%)の組成で特性を評価した。この結果、MgOを5.0(mol%)以下の範囲で含み、主成分合計量を95(mol%)以上の組成としても、ＦＦ値が77の極めて高い特性を有することが確かめられた。また、No.38のように、2.0(mol%)のMgOと1.5(mol%)のTiO₂を含む組成も評価した結果、MgOと同時にTiO₂を含む組成でも、これら副成分の合計が3.5(mol%)すなわち5(mol%)以下の組成において、良好な特性が得られることが確認できた。 Moreover, in Table 2, No. 36-39 examined the glass composition containing MgO in addition to the four main components. TeO ₂ and 40.6~66.5 (mol%), the _{_{Bi 2 O 3 4.2~7.2 (mol%}} ), Li a _{2 O 16.0~21.4 (mol%),} ZnO and 12.0~28.4 (mol%), 0.2~ the MgO The characteristics were evaluated with a composition of 5.0 (mol%), TiO ₂ from 0 to 1.5 (mol%), and the total amount of main components from 95.0 to 99.8 (mol%). As a result, it was confirmed that even when the composition contains MgO in the range of 5.0 (mol%) or less and the total amount of the main components is 95 (mol%) or more, the composition has extremely high characteristics with an FF value of 77. Further, as a result of evaluating the composition containing 2.0 (mol%) MgO and 1.5 (mol%) TiO ₂ as in No. 38, even in the composition containing TiO ₂ simultaneously with MgO, the total of these subcomponents was 3.5. It was confirmed that good characteristics were obtained at a composition of (mol%), that is, 5 (mol%) or less.

また、No.40〜42は主成分４成分に加えてTiO₂を含むガラス組成を検討したものである。TeO₂を50.1〜73.5(mol%)、Bi₂O₃を1.4〜4.0(mol%)、Li₂Oを18.0〜27.1(mol%)、ZnOを3.0〜16.4(mol%)、MgOを0〜1.0(mol%)、TiO₂を0.5〜5.0(mol%)、主成分合計量を95.0〜98.5(mol%)の組成で特性を評価した。この結果、TiO₂を5.0(mol%)以下の範囲で含み、主成分合計量を95(mol%)以上の組成としても、ＦＦ値が76以上の十分に高い特性を有することが確かめられた。 Nos. 40 to 42 are for examining glass compositions containing TiO ₂ in addition to the four main components. TeO ₂ and 50.1~73.5 (mol%), the _{_{Bi 2 O 3 1.4~4.0 (mol%}} ), Li a _{2 O 18.0~27.1 (mol%),} ZnO a 3.0~16.4 (mol%), 0~ the MgO The characteristics were evaluated with a composition of 1.0 (mol%), TiO ₂ of 0.5 to 5.0 (mol%), and the total amount of main components of 95.0 to 98.5 (mol%). As a result, it was confirmed that the composition has a sufficiently high FF value of 76 or more even when the composition contains TiO ₂ in the range of 5.0 (mol%) or less and the total amount of main components is 95 (mol%) or more. .

また、No.43〜45は主成分４成分に加えてV₂O₅を含むガラス組成を検討したものである。TeO₂を42.1〜72.7(mol%)、Bi₂O₃を2.0〜4.2(mol%)、Li₂Oを19.0〜24.0(mol%)、ZnOを5.0〜28.3(mol%)、TiO₂を0〜1.0(mol%)、V₂O₅を0.3〜4.5(mol%)、主成分合計量を95.5〜99.7(mol%)の組成で特性を評価した。この結果、V₂O₅を4.5(mol%)以下の範囲で含み、主成分合計量を95.5(mol%)以上の組成としても、ＦＦ値が77の極めて高い特性を有することが確かめられた。また、No.44のように、1.0(mol%)のTiO₂と2.3(mol%)のV₂O₅を含む組成も評価した結果、V₂O₅と同時にTiO₂を含む組成でも、これら副成分の合計が3.3(mol%)すなわち5(mol%)以下の組成において、良好な特性が得られることが確認できた。 Nos. 43 to 45 are for examining glass compositions containing V ₂ O ₅ in addition to the four main components. TeO ₂ and 42.1~72.7 (mol%), the _{_{Bi 2 O 3 2.0~4.2 (mol%}} ), Li 2 O and 19.0~24.0 (mol%), ZnO a 5.0~28.3 (mol%), a TiO ₂ 0 The characteristics were evaluated with compositions of ˜1.0 (mol%), V ₂ O ₅ of 0.3 to 4.5 (mol%), and the total amount of main components of 95.5 to 99.7 (mol%). As a result, it was confirmed that V ₂ O ₅ was contained in the range of 4.5 (mol%) or less and the composition had a very high FF value of 77 even when the total amount of the main components was 95.5 (mol%) or more. . Moreover, as a result of evaluating a composition containing 1.0 (mol%) TiO ₂ and 2.3 (mol%) V ₂ O ₅ as in No. 44, even a composition containing TiO ₂ simultaneously with V ₂ O ₅ It was confirmed that good characteristics could be obtained with a composition having a total of the subcomponents of 3.3 (mol%), that is, 5 (mol%) or less.

また、No.46〜48は主成分４成分に加えてCr₂O₃を含むガラス組成を検討したものである。TeO₂を61.0〜64.8(mol%)、Bi₂O₃を5.2〜10.0(mol%)、Li₂Oを16.7〜17.0(mol%)、ZnOを8.0〜11.6(mol%)、MgOを0〜0.3(mol%)、TiO₂を0〜1.3(mol%)、Cr₂O₃を0.2〜4.0(mol%)、主成分合計量を96.0〜99.8(mol%)の組成、すなわち、TeO₂の一部をCr₂O₃に置き換えた組成等で特性を評価した。この結果、Cr₂O₃を4.0(mol%)以下の範囲で含み、主成分合計量を96.0(mol%)以上の組成としても、ＦＦ値が76以上の十分に高い特性を有することが確かめられた。また、No.47のように、0.3(mol%)のMgO、1.3(mol%)のTiO₂、1.8(mol%)のCr₂O₄を含む組成も評価した結果、Cr₂O₄と同時にMgOおよびTiO₂を含む組成でも、これら副成分の合計が3.4(mol%)すなわち5(mol%)以下の組成において、良好な特性が得られることが確認できた。 Nos. 46 to 48 were examined for glass compositions containing Cr ₂ O ₃ in addition to the four main components. TeO ₂ and 61.0~64.8 (mol%), the _{_{Bi 2 O 3 5.2~10.0 (mol%}} ), Li a _{2 O 16.7~17.0 (mol%),} ZnO a 8.0~11.6 (mol%), 0~ the MgO 0.3 (mol%), a TiO ₂ 0~1.3 (mol%), the _{_{Cr 2 O 3 0.2~4.0 (mol%}} ), the composition of the main component total amount from 96.0 to 99.8 in (mol%), i.e., the TeO ₂ The characteristics were evaluated using a composition or the like in which a portion was replaced with Cr ₂ O ₃ . As a result, even if the composition contains Cr ₂ O ₃ in the range of 4.0 (mol%) or less and the total amount of main components is 96.0 (mol%) or more, it is confirmed that the composition has sufficiently high characteristics with an FF value of 76 or more. It was. Further, as No.47, MgO of 0.3 (mol%), 1.3 TiO 2 of (mol%), 1.8 (mol %) Cr 2 O 4 was also evaluated the composition containing the result of, at the same time as Cr ₂ O ₄ Even in a composition containing MgO and TiO ₂ , it was confirmed that good characteristics were obtained in a composition in which the total of these subcomponents was 3.4 (mol%), that is, 5 (mol%) or less.

また、No.49〜51は主成分４成分に加えてMnO₂を含むガラス組成を検討したものである。TeO₂を52.9〜67.7(mol%)、Bi₂O₃を5.0〜10.3(mol%)、Li₂Oを22.0〜24.2(mol%)、ZnOを5.0〜8.5(mol%)、MgOを0〜0.9(mol%)、V₂O₅を0〜0.3(mol%)、MnO₂を0.3〜5.0(mol%)、主成分合計量を95.0〜99.7(mol%)の組成、すなわち、TeO₂の一部をMnO₂に置き換えた組成等で特性を評価した。この結果、MnO₂を5.0(mol%)以下の範囲で含み、主成分合計量を95.0(mol%)以上の組成としても、ＦＦ値が76以上の十分に高い特性を有することが確かめられた。また、No.50のように、0.9(mol%)のMgO、0.3(mol%)のV₂O₅、2.9(mol%)のMnO₂を含む組成も評価した結果、MnO₂と同時にMgOおよびV₂O₅を含む組成でも、これら副成分の合計が4.1(mol%)すなわち5(mol%)以下の組成において、良好な特性が得られることが確認できた。 Nos. 49 to 51 are for examining glass compositions containing MnO ₂ in addition to the four main components. TeO ₂ and 52.9~67.7 (mol%), the _{_{Bi 2 O 3 5.0~10.3 (mol%}} ), Li a _{2 O 22.0~24.2 (mol%),} ZnO and 5.0~8.5 (mol%), 0~ the MgO 0.9 (mol%), the _{_{V 2 O 5 0~0.3 (mol%}} ), the MnO ₂ 0.3~5.0 (mol%), the composition of the main component total amount from 95.0 to 99.7 in (mol%), i.e., the TeO ₂ The characteristics were evaluated by using a composition in which a part was replaced with MnO ₂ . As a result, it was confirmed that the composition has a sufficiently high FF value of 76 or more even when the composition contains MnO ₂ in the range of 5.0 (mol%) or less and the total amount of main components is 95.0 (mol%) or more. . Further, as No.50, MgO of 0.9 (mol%), 0.3 V 2 O 5 in (mol%), 2.9 (mol %) result also compositions comprising MnO ₂ were evaluated for, MnO ₂ simultaneously MgO and Even in the composition containing V ₂ O ₅ , it was confirmed that good characteristics were obtained in a composition in which the total of these subcomponents was 4.1 (mol%), that is, 5 (mol%) or less.

また、No.52〜54は主成分４成分に加えてFe₂O₃を含むガラス組成を検討したものである。TeO₂を48.3〜74.9(mol%)、Bi₂O₃を3.5〜13.1(mol%)、Li₂Oを16.0〜20.4(mol%)、ZnOを5.0〜14.2(mol%)、TiO₂を0〜0.4(mol%)、Cr₂O₃を0〜0.9(mol%)、MnO₂を0〜0.6(mol%)、Fe₂O₃を0.6〜4.0(mol%)、主成分合計量を96.0〜99.4(mol%)の組成で特性を評価した。この結果、Fe₂O₃を4.0(mol%)以下の範囲で含み、主成分合計量を96.0(mol%)以上の組成としても、ＦＦ値が77の極めて高い特性を有することが確かめられた。また、No.53のように、0.4(mol%)のTiO₂、0.9(mol%)のCr₂O₃、0.6(mol%)のMnO₂、2.1(mol%)のFe₂O₃を含む組成も評価した結果、Fe₂O₃と同時にTiO₂、Cr₂O₃、MnO₂を含む組成でも、これら副成分の合計が4.0(mol%)すなわち5(mol%)以下の組成において、良好な特性が得られることが確認できた。 Nos. 52 to 54 were examined for glass compositions containing Fe ₂ O ₃ in addition to the four main components. TeO ₂ and 48.3~74.9 (mol%), the _{_{Bi 2 O 3 3.5~13.1 (mol%}} ), Li 2 O and 16.0~20.4 (mol%), ZnO a 5.0~14.2 (mol%), a TiO ₂ 0 ~0.4 (mol%), the _{_{Cr 2 O 3 0~0.9 (mol%}} ), the MnO ₂ 0~0.6 (mol%), the _{_{Fe 2 O 3 0.6~4.0 (mol%}} ), the main component total amount 96.0 The properties were evaluated with a composition of ~ 99.4 (mol%). As a result, it was confirmed that Fe ₂ O ₃ was included in the range of 4.0 (mol%) or less and the composition had a very high FF value of 77 even when the total amount of the main components was 96.0 (mol%) or more. . Further, as No.53, including 0.4 TiO ₂ of _{(mol%), 0.9 Cr 2} O 3 in _{(mol%), 0.6 MnO 2} , Fe 2 O 3 of 2.1 (mol%) of (mol%) As a result of evaluating the composition, even in the composition containing TiO ₂ , Cr ₂ O ₃ and MnO ₂ at the same time as Fe ₂ O _{3, the} composition of these subcomponents is good at a composition of 4.0 (mol%), that is, 5 (mol%) or less. It has been confirmed that excellent characteristics can be obtained.

また、No.55〜57は主成分４成分に加えてCo₃O₄を含むガラス組成を検討したものである。TeO₂を51.4〜70.7(mol%)、Bi₂O₃を2.5〜8.0(mol%)、Li₂Oを16.0〜25.1(mol%)、ZnOを5.0〜18.2(mol%)、V₂O₅を0〜1.2(mol%)、Co₃O₄を0.3〜5.0(mol%)、主成分合計量を95.0〜99.7(mol%)の組成、すなわち、TeO₂の一部をCo₃O₄に置き換えた組成等で特性を評価した。この結果、Co₃O₄を5.0(mol%)以下の範囲で含み、主成分合計量を95.0(mol%)以上の組成としても、ＦＦ値が77の極めて高い特性を有することが確かめられた。また、No.56のように、1.2(mol%)のV₂O₅、1.6(mol%)のCo₃O₄を含む組成も評価した結果、Co₃O₄と同時にV₂O₅を含む組成でも、これら副成分の合計が2.8(mol%)すなわち5(mol%)以下の組成において、良好な特性が得られることが確認できた。 Nos. 55 to 57 are glass compositions containing Co ₃ O ₄ in addition to the four main components. TeO ₂ and 51.4~70.7 (mol%), the _{_{Bi 2 O 3 2.5~8.0 (mol%}} ), Li 2 O and 16.0~25.1 (mol%), a ZnO 5.0~18.2 (mol%), V 2 O 5 the _{0~1.2 (mol%), Co 3} O 4 and 0.3 to 5.0 (mol%), the composition of the main component total amount 95.0 to 99.7 (mol%), i.e., a portion of TeO ₂ to Co ₃ O ₄ The characteristics were evaluated based on the replaced composition. As a result, it was confirmed that even if the composition contains Co ₃ O ₄ in the range of 5.0 (mol%) or less and the total amount of the main components is 95.0 (mol%) or more, it has extremely high characteristics with an FF value of 77. . Further, as in No. 56, as a result of evaluating a composition containing 1.2 (mol%) of V ₂ O ₅ and 1.6 (mol%) of Co ₃ O ₄ , V ₂ O ₅ was contained simultaneously with Co ₃ O _4. Even in the composition, it was confirmed that good characteristics could be obtained when the total of these subcomponents was 2.8 (mol%), that is, 5 (mol%) or less.

また、No.58〜60は主成分４成分に加えてNiOを含むガラス組成を検討したものである。TeO₂を65.2〜72.8(mol%)、Bi₂O₃を3.1〜4.0(mol%)、Li₂Oを18.0〜21.0(mol%)、ZnOを2.0〜9.3(mol%)、Cr₂O₃を0〜0.6(mol%)、Fe₂O₃を0〜0.7(mol%)、NiOを0.2〜4.5(mol%)、主成分合計量を95.5〜99.8(mol%)の組成で特性を評価した。この結果、NiOを4.5(mol%)以下の範囲で含み、主成分合計量を95.5(mol%)以上の組成としても、ＦＦ値が77の極めて高い特性を有することが確かめられた。また、No.59のように、0.6(mol%)のCr₂O₄、0.7(mol%)のFe₂O₃、1.5(mol%)のNiOを含む組成も評価した結果、NiOと同時にCr₂O₄、Fe₂O₃を含む組成でも、これら副成分の合計が2.8(mol%)すなわち5(mol%)以下の組成において、良好な特性が得られることが確認できた。 Nos. 58 to 60 are for examining glass compositions containing NiO in addition to the four main components. TeO ₂ and _{65.2~72.8 (mol%), Bi 2} O 3 and 3.1~4.0 (mol%), the _{Li 2 O 18.0~21.0 (mol%)} , a ZnO 2.0~9.3 (mol%), Cr 2 O 3 the 0~0.6 (mol%), the _{_{Fe 2 O 3 0~0.7 (mol%}} ), the NiO 0.2~4.5 (mol%), assess the characteristics of the main component total amount with the composition of from 95.5 to 99.8 (mol%) did. As a result, it was confirmed that even when the composition contains NiO in the range of 4.5 (mol%) or less and the total amount of the main components is 95.5 (mol%) or more, the composition has extremely high FF value of 77. In addition, as in No. 59, as a result of evaluating a composition containing 0.6 (mol%) Cr ₂ O ₄ , 0.7 (mol%) Fe ₂ O ₃ and 1.5 (mol%) NiO, Cr was simultaneously formed with NiO. It was confirmed that even when the composition contains ₂ O ₄ and Fe ₂ O ₃ , good characteristics can be obtained when the total of these subcomponents is 2.8 (mol%), that is, 5 (mol%) or less.

また、No.61〜63は主成分４成分に加えてCuOを含むガラス組成を検討したものである。TeO₂を59.1〜65.6(mol%)、Bi₂O₃を5.7〜8.2(mol%)、Li₂Oを19.0〜21.4(mol%)、ZnOを7.3〜9.5(mol%)、MgOを0〜0.7(mol%)、MnO₂を0〜1.2(mol%)、CuOを0.2〜4.8(mol%)、主成分合計量を95.2〜99.8(mol%)の組成、すなわち、TeO₂の一部をCuOに置き換えた組成等で特性を評価した。この結果、CuOを4.8(mol%)以下の範囲で含み、主成分合計量を95.2(mol%)以上の組成としても、ＦＦ値が77以上の極めて高い特性を有することが確かめられた。また、No.62のように、0.7(mol%)のMgO、1.2(mol%)のMnO₂、2.1(mol%)のCuOを含む組成も評価した結果、CuOと同時にMgO、NiOを含む組成でも、これら副成分の合計が4.0(mol%)すなわち5(mol%)以下の組成において、良好な特性が得られることが確認できた。 Nos. 61 to 63 were examined for glass compositions containing CuO in addition to the four main components. TeO ₂ 59.1-65.6 (mol%), Bi ₂ O ₃ 5.7-8.2 (mol%), Li ₂ O 19.0-21.4 (mol%), ZnO 7.3-9.5 (mol%), MgO 0- 0.7 (mol%), the _{MnO 2 0~1.2 (mol%),} CuO and from 0.2 to 4.8 (mol%), the composition of the main component total amount from 95.2 to 99.8 in (mol%), i.e., a portion of TeO ₂ The characteristics were evaluated by the composition replaced with CuO. As a result, it was confirmed that even if the composition contains CuO in the range of 4.8 (mol%) or less and the total amount of the main components is 95.2 (mol%) or more, it has extremely high characteristics with an FF value of 77 or more. Further, as No.62, MgO of 0.7 (mol%), 1.2 MnO 2 in (mol%), 2.1 (mol %) result composition were also evaluated containing the CuO of the composition comprising CuO simultaneously MgO, the NiO However, it has been confirmed that good characteristics can be obtained in a composition in which the total of these subcomponents is 4.0 (mol%), that is, 5 (mol%) or less.

上記のNo.36〜63の評価結果によれば、主成分４成分に加えて副成分TiO₂、V₂O₅、Cr₂O₃、MnO₂、Fe₂O₃、Co₃O₄、NiO、CuOの何れかを１〜４種含むガラス組成系では、副成分量が5.0(mol%)以下の範囲、すなわち、TeO₂を40.6〜74.9(mol%)、Bi₂O₃を1.4〜13.1(mol%)、Li₂Oを16.0〜27.1(mol%)、ZnOを2.0〜28.4(mol%)、MgO等を合計で0〜5.0(mol%)の範囲で、ＦＦ値が76〜78の良好な特性が得られる。 According to the evaluation result of the Nanba36～63, principal component 4 in addition to the ingredients subcomponent _{_{_{TiO 2, V 2 O 5,}}} Cr 2 O 3, MnO 2, Fe 2 O 3, Co 3 O 4, NiO In the glass composition system containing 1 to 4 kinds of CuO, the amount of subcomponents is in the range of 5.0 (mol%) or less, that is, TeO ₂ is 40.6 to 74.9 (mol%), Bi ₂ O ₃ is 1.4 to 13.1. (mol%), Li ₂ O and 16.0~27.1 (mol%), ZnO a 2.0~28.4 (mol%), in the range of 0 to 5.0 and MgO and the like in total (mol%), FF value is 76 to 78 Good characteristics can be obtained.

また、表２において、No.64〜66は主成分４成分に加えてB₂O₃を含むガラス組成を検討したものである。TeO₂を58.0〜64.0(mol%)、Bi₂O₃を1.0〜3.0(mol%)、Li₂Oを17.0〜20.0(mol%)、ZnOを14.0〜19.0(mol%)、B₂O₃を1.0〜4.0(mol%)、主成分合計量を96.0〜99.0(mol%)の組成で特性を評価し、B₂O₃の許容量を検討した。B₂O₃が3.0(mol%)以下のNo.64、65は、ＦＦ値が75以上の良好な結果が得られるが、B₂O₃が4.0(mol%)のNo.66では、ＦＦ値が74に留まった。この評価結果によれば、B₂O₃量は3.0(mol%)以下にする必要がある。 In Table 2, Nanba64～66 was done in order to investigate the glass composition containing B ₂ O ₃ in addition to the main component 4 components. TeO ₂ and 58.0~64.0 (mol%), the _{_{Bi 2 O 3 1.0~3.0 (mol%}} ), Li 2 O and 17.0~20.0 (mol%), ZnO and _{14.0~19.0 (mol%), B 2} O 3 Was evaluated with the composition of 1.0 to 4.0 (mol%) and the total amount of the main components of 96.0 to 99.0 (mol%), and the allowable amount of B ₂ O ₃ was examined. Nos. 64 and 65 with B ₂ O ₃ of 3.0 (mol%) or less give good results with an FF value of 75 or more, but with No. 66 with B ₂ O ₃ of 4.0 (mol%), FF The value stayed at 74. According to this evaluation result, the amount of B ₂ O ₃ needs to be 3.0 (mol%) or less.

また、表３に示すNo.67〜93は主成分４成分に加えてMgOおよびWO₃を含むガラス組成を検討したものである。これらのうち、No.67〜74は、TeO₂を51.0〜64.4(mol%)、Bi₂O₃を1.0〜5.0(mol%)、Li₂Oを11.2〜21.8(mol%)、ZnOを12.0〜19.0(mol%)、MgOを0〜5.0(mol%)、WO₃を0.4〜11.0(mol%)、主成分合計量を89.0〜98.0(mol%)の組成で特性を評価し、WO₃の許容量を確認した。WO₃が10.0(mol%)以下のNo.67〜73では、ＦＦ値が75以上に保たれ、特に、WO₃量が4.8(mol%)以下、主成分合計量が93.3(mol%)以上の組成では、ＦＦ値が77以上の極めて良好な結果が得られることが確認できた。WO₃量が11.0(mol%)のNo.74では、ＦＦ値が74に留まった。 Nos. 67 to 93 shown in Table 3 are for examining glass compositions containing MgO and WO ₃ in addition to the four main components. Among these, No. 67 to 74 are TeO ₂ 51.0 to 64.4 (mol%), Bi ₂ O ₃ 1.0 to 5.0 (mol%), Li ₂ O 11.2 to 21.8 (mol%), ZnO 12.0 -19.0 (mol%), MgO 0-5.0 (mol%), WO ₃ 0.4-41.0 (mol%), the main component total amount of the composition of 89.0-98.0 (mol%) to evaluate the characteristics, WO ₃ The allowable amount of was confirmed. In No. 67 to 73 with WO ₃ of 10.0 (mol%) or less, the FF value is maintained at 75 or more, and in particular, the amount of WO ₃ is 4.8 (mol%) or less, and the total amount of main components is 93.3 (mol%) or more. With this composition, it was confirmed that an extremely good result having an FF value of 77 or more was obtained. In No. 74 having a WO ₃ amount of 11.0 (mol%), the FF value remained at 74.

No.75〜78は、WO₃を含む組成において、TeO₂量の許容範囲を確認したものである。TeO₂を33.0〜83.3(mol%)、Bi₂O₃を0.2〜9.2(mol%)、Li₂Oを11.4〜26.2(mol%)、ZnOを0.3〜31.8(mol%)、WO₃を0.5〜6.1(mol%)、主成分合計量を93.9〜99.5(mol%)の範囲で特性を評価したところ、WO₃を含まない場合と同様に、TeO₂量が35.0〜83.0(mol%)の範囲でＦＦ値75の良好な結果が得られることが確認できた。TeO₂量が33.0(mol%)のNo.75、83.4(mol%)のNo.78では、ＦＦ値が74に留まった。 Nos. 75 to 78 confirm the allowable range of the amount of TeO ₂ in the composition containing WO ₃ . TeO ₂ and 33.0~83.3 (mol%), the _{_{Bi 2 O 3 0.2~9.2 (mol%}} ), Li 2 O and 11.4~26.2 (mol%), ZnO a 0.3~31.8 (mol%), the WO ₃ 0.5 ~6.1 (mol%), was evaluated the characteristics of the main component total amount in the range of 93.9~99.5 (mol%), as in the case of not including WO _3, TeO ₂ weight 35.0 to 83.0 of (mol%) It was confirmed that good results with an FF value of 75 were obtained in the range. In No. 75 with TeO ₂ amount of 33.0 (mol%) and No. 78 with 83.4 (mol%), the FF value remained at 74.

No.79〜85は、WO₃を含む組成において、Li₂O量の許容範囲を確認したものである。TeO₂を49.8〜62.8(mol%)、Bi₂O₃を1.2〜6.2(mol%)、Li₂Oを9.0〜31.0(mol%)、ZnOを5.0〜26.0(mol%)、MgOを2.0〜4.0(mol%)、WO₃を2.5〜7.0(mol%)、主成分合計量を91.0〜97.5(mol%)の範囲で特性を評価したところ、Li₂O量が10.0〜30.0(mol%)の範囲でＦＦ値75以上の良好な結果が得られることが確認できた。すなわち、Li₂O量の下限値は、WO₃を含まない場合よりも少ない10.0(mol%)に広がる。上限値はWO₃を含まない場合と同様である。Li₂O量が9.0(mol%)のNo.79、31.0(mol%)のNo.85では、ＦＦ値が74に留まった。 Nos. 79 to 85 confirm the allowable range of the amount of Li ₂ O in the composition containing WO ₃ . TeO ₂ 49.8-62.8 (mol%), Bi ₂ O ₃ 1.2-6.2 (mol%), Li ₂ O 9.0-31.0 (mol%), ZnO 5.0-26.0 (mol%), MgO 2.0- When the characteristics were evaluated in the range of 4.0 (mol%), WO ₃ 2.5 to 7.0 (mol%) and the total amount of main components 91.0 to 97.5 (mol%), the amount of Li ₂ O was 10.0 to 30.0 (mol%) It was confirmed that good results with an FF value of 75 or more were obtained in the above range. That is, the lower limit of the amount of Li ₂ O extends to 10.0 (mol%), which is smaller than when WO ₃ is not included. The upper limit is the same as when WO ₃ is not included. In No. 79 with a Li ₂ O content of 9.0 (mol%) and No. 85 with 31.0 (mol%), the FF value remained at 74.

No.86〜89は、WO₃を含む組成において、Bi₂O₃量の許容範囲を確認したものである。TeO₂を43.7〜69.6(mol%)、Bi₂O₃を0〜21.5(mol%)、Li₂Oを16.0〜24.1(mol%)、ZnOを5.7〜24.0(mol%)、WO₃を0.5〜4.9(mol%)、主成分合計量を95.1〜99.5(mol%)の範囲で特性を評価したところ、WO₃を含まない場合と同様に、Bi₂O₃量が0.1〜20.0(mol%)の範囲でＦＦ値75の良好な結果が得られることが確認できた。Bi₂O₃量が0(mol%)のNo.86、21.5(mol%)のNo.89では、ＦＦ値が74に留まった。 Nos. 86 to 89 confirm the allowable range of Bi ₂ O ₃ content in compositions containing WO ₃ . TeO ₂ and 43.7~69.6 (mol%), the _{_{Bi 2 O 3 0~21.5 (mol%}} ), Li 2 O and 16.0~24.1 (mol%), ZnO a 5.7~24.0 (mol%), the WO ₃ 0.5 ~4.9 (mol%), it was evaluated the characteristics of the main component total amount in the range of 95.1~99.5 (mol%), as in the case of not including WO _3, Bi ₂ O ₃ amount is 0.1 to 20.0 (mol% It was confirmed that good results with an FF value of 75 were obtained within the range of In No. 86 with Bi ₂ O ₃ content of 0 (mol%) and No. 89 with 21.5 (mol%), the FF value remained at 74.

No.90〜93は、WO₃を含む組成において、ZnO量の許容範囲を確認したものである。TeO₂を36.2〜69.5(mol%)、Bi₂O₃を1.4〜3.2(mol%)、Li₂Oを16.4〜24.8(mol%)、ZnOを0〜42.0(mol%)、WO₃を2.4〜8.2(mol%)、主成分合計量を91.8〜97.6(mol%)の範囲で特性を評価したところ、WO₃を含まない場合と同様に、ZnO量が0.1〜40.0(mol%)の範囲でＦＦ値75の良好な結果が得られることが確認できた。ZnO量が0(mol%)のNo.90ではＦＦ値が73に留まり、42.0(mol%)のNo.93では、ＦＦ値が74に留まった。 No.90~93, in compositions containing WO _3, it is obtained by confirming the allowable range of the ZnO amount. TeO ₂ and _{36.2~69.5 (mol%), Bi 2} O 3 and _{1.4~3.2 (mol%), Li 2} O and 16.4~24.8 (mol%), ZnO and 0~42.0 (mol%), WO ₃ 2.4 When the characteristics were evaluated in the range of ~ 8.2 (mol%) and the total amount of the main components in the range of 91.8 to 97.6 (mol%), the ZnO content was in the range of 0.1 to 40.0 (mol%), as in the case of not containing WO _3. It was confirmed that a good result with an FF value of 75 was obtained. The FF value stayed at 73 for No. 90 with the ZnO content of 0 (mol%), and the FF value stayed at 74 for No. 93 with 42.0 (mol%).

表４に示すNo.94〜112は、WO₃を含む組成において、MgO、TiO₂等の他の成分の許容量および主成分量の下限値を確認したものである。TeO₂を38.0〜64.2(mol%)、Bi₂O₃を1.4〜18.1(mol%)、Li₂Oを12.3〜28.6(mol%)、ZnOを5.1〜34.1(mol%)、MgO、TiO₂等を0〜5.0(mol%)、WO₃を2.4〜9.2(mol%)、主成分合計量を90.1〜96.8(mol%)の範囲で特性を評価したところ、何れもＦＦ値が76以上の良好な結果が得られることが確認できた。また、No.97のように、2.3(mol%)のTiO₂、1.0(mol%)のCo₃O₄、1.2(mol%)のNiO、4.3(mol%)のWO₃を含む組成も評価した結果、副成分としてWO₃の他に２種以上を同時に含む組成でも、これら副成分の合計が8.8(mol%)すなわち10(mol%)以下の組成において、良好な特性が得られることが確認できた。 Nos. 94 to 112 shown in Table 4 confirm the lower limit of the allowable amount and the main component amount of other components such as MgO and TiO ₂ in the composition containing WO ₃ . TeO ₂ 38.0 to 64.2 (mol%), Bi ₂ O ₃ 1.4 to 18.1 (mol%), Li ₂ O 12.3 to 28.6 (mol%), ZnO 5.1 to 34.1 (mol%), MgO, TiO ₂ The characteristics were evaluated in the range of 0 to 5.0 (mol%), WO ₃ to 2.4 to 9.2 (mol%), and the total amount of main components from 90.1 to 96.8 (mol%). It was confirmed that good results were obtained. Also, as in No. 97, a composition containing 2.3 (mol%) TiO ₂ , 1.0 (mol%) Co ₃ O ₄ , 1.2 (mol%) NiO, 4.3 (mol%) WO ₃ was also evaluated. As a result, even if the composition contains two or more kinds in addition to WO ₃ as accessory components, good characteristics can be obtained when the total of these accessory components is 8.8 (mol%), that is, 10 (mol%) or less. It could be confirmed.

上記表３，表４に示す評価結果によれば、WO₃を含むガラス組成では、WO₃が10.0(mol%)以下で良好な特性が得られ、また、Li₂Oが10.0〜30.0(mol%)の範囲で良好な特性が得られる。すなわち、WO₃を含まない場合よりもLi₂O量の下限値が下がり、10.0(mol%)で足りるようになる。また、WO₃を含む組成では、主成分合計量は90.0(mol%)以上で足り、MgO、TiO₂等の他の成分が合計で5.0(mol%)以下の範囲で許容される。 Table 3, according to the evaluation results shown in Table 4, the glass composition containing WO _3, WO ₃ is 10.0 (mol%) satisfactory characteristics were obtained in the following, also, Li ₂ O is 10.0 to 30.0 (mol %), Good characteristics can be obtained. That is, the lower limit of the amount of Li ₂ O is lower than when no WO ₃ is contained, and 10.0 (mol%) is sufficient. In the composition containing WO ₃ , the total amount of main components is sufficient to be 90.0 (mol%) or more, and other components such as MgO and TiO ₂ are allowed in the range of 5.0 (mol%) or less in total.

以上の評価結果によれば、本実施例の電極用ペーストは、WO₃を必須としない場合においては、35.0〜83.0(mol%)のTeO₂、0.1〜20.0(mol%)のBi₂O₃、15.5〜30.0(mol%)のLi₂O、0.1〜40.0(mol%)のZnOの４成分から成るガラス、或いは、これらを主成分としてその合計量が95(mol%)以上で、副成分としてMgO、TiO₂、V₂O₅、Cr₂O₃、MnO₂、Fe₂O₃、Co₃O₄、NiO、CuO、WO₃のうちの少なくとも１種を含むガラスを、ガラスフリットとして含むことから、シリコン基板２０に対して受光面電極２８をファイヤースルーで形成すると、基板２０との接着強度が高く、且つ接触抵抗が低い電極が得られるので、上述したようにＦＦ値の高い電池特性の優れた太陽電池セルが得られる。 According to the above evaluation results, in the case where WO ₃ is not essential, the electrode paste of this example is 35.0 to 83.0 (mol%) of TeO ₂ , 0.1 to 20.0 (mol%) of Bi ₂ O _3. , 15.5 to 30.0 (mol%) Li ₂ O, 0.1 to 40.0 (mol%) ZnO four-component glass, or the total amount of these as the main component is 95 (mol%) or more, secondary component Glass containing at least one of MgO, TiO ₂ , V ₂ O ₅ , Cr ₂ O ₃ , MnO ₂ , Fe ₂ O ₃ , Co ₃ O ₄ , NiO, CuO, WO ₃ as glass frit Therefore, when the light-receiving surface electrode 28 is formed on the silicon substrate 20 by fire-through, an electrode having high adhesion strength with the substrate 20 and low contact resistance can be obtained. As described above, battery characteristics having a high FF value are obtained. Excellent solar cells can be obtained.

また、WO₃を必須とする場合においては、35.0〜83.0(mol%)のTeO₂、0.1〜20.0(mol%)のBi₂O₃、10.0〜30.0(mol%)のLi₂O、0.1〜40.0(mol%)のZnO、0.4〜10.0(mol%)のWO₃から成るガラス、或いは、主成分合計量が90(mol%)以上でこれに更にMgO、TiO₂、V₂O₅、Cr₂O₃、MnO₂、Fe₂O₃、Co₃O₄、NiO、CuOのうちの少なくとも１種を含むガラスを、ガラスフリットとして含むことから、シリコン基板２０に対して受光面電極２８をファイヤースルーで形成すると、基板２０との接着強度が高く、且つ接触抵抗が低い電極が得られるので、上述したようにＦＦ値の高い電池特性の優れた太陽電池セルが得られる。 Further, in the case of the mandatory WO ₃ is, TeO ₂ of _{35.0~83.0 (mol%), Bi 2} O 3 of _{0.1~20.0 (mol%), Li 2} O of 10.0~30.0 (mol%), 0.1~ 40.0 ZnO of (mol%), glass made of WO ₃ of 0.4 to 10.0 (mol%), or, further MgO to main component total amount 90 (mol%) or _{_{_{more, TiO 2, V 2 O 5}}} , Cr _Since glass containing at least one of ₂ O ₃ , MnO ₂ , Fe ₂ O ₃ , Co ₃ O ₄ , NiO, and CuO is included as a glass frit, the light receiving surface electrode 28 is fired with respect to the silicon substrate 20. When formed through, an electrode having high adhesive strength with the substrate 20 and low contact resistance can be obtained, so that a solar battery cell having a high FF value and excellent battery characteristics can be obtained as described above.

以上、本発明を図面を参照して詳細に説明したが、本発明は更に別の態様でも実施でき、その主旨を逸脱しない範囲で種々変更を加え得るものである。 As mentioned above, although this invention was demonstrated in detail with reference to drawings, this invention can be implemented also in another aspect, A various change can be added in the range which does not deviate from the main point.

１０：太陽電池、１２：太陽電池モジュール、１４：封止材、１６：表面ガラス、１８：保護フィルム、２０：シリコン基板、２２：ｎ層、２４：ｐ⁺層、２６：反射防止膜、２８：受光面電極、３０：裏面電極、３２：受光面、３４：全面電極、３６：帯状電極、３８：半田リボン 10: solar cell, 12: solar cell module, 14: sealing material, 16: surface glass, 18: protective film, 20: silicon substrate, 22: n layer, 24: p ⁺ layer, 26: antireflection film, 28 : Light receiving surface electrode, 30: Back electrode, 32: Light receiving surface, 34: Full surface electrode, 36: Strip electrode, 38: Solder ribbon

Claims

A solar cell electrode comprising a conductive powder, a glass frit made of lead-free glass, and a vehicle, which is applied to one surface of a semiconductor substrate and subjected to a firing treatment to form a solar cell electrode by fire-through. Paste for
The lead-free glass contains 35 to 83 (mol%) Te, 0.1 to 20 (mol%) Bi, 15.5 to 30 (mol%) Li, and 0.1 to 40 (mol%) Zn in terms of oxides, respectively. A total of 95 (mol%) or more and a total of 0 to 5 (mol%) of Mg, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, W in terms of oxides, and B A solar cell electrode paste characterized by not containing .

A solar cell was allowed to electrically contact the semiconductor substrate of the electrode pixel provided via an insulating film on a semiconductor substrate,
The solar cell produced from the paste for a solar battery electrode according to claim 1.