JP2015141941A - Solar battery and solar battery module - Google Patents

Solar battery and solar battery module Download PDF

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JP2015141941A
JP2015141941A JP2014012603A JP2014012603A JP2015141941A JP 2015141941 A JP2015141941 A JP 2015141941A JP 2014012603 A JP2014012603 A JP 2014012603A JP 2014012603 A JP2014012603 A JP 2014012603A JP 2015141941 A JP2015141941 A JP 2015141941A
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light
conductive film
transmitting conductive
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solar cell
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祐樹 津田
Yuki Tsuda
祐樹 津田
博文 小西
Hirofumi Konishi
博文 小西
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Mitsubishi Electric Corp
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Abstract

PROBLEM TO BE SOLVED: To provide a solar battery having both functions of effectively capturing light with a wavelength usable in the solar battery and reflecting infrared ray causing a temperature rise of the solar battery, among light entering the solar battery, without adversely affecting economic efficiency and productivity.SOLUTION: A solar battery includes a first electrode 2 comprising a light transmitting conductive material on a light receiving surface side of a photoelectric conversion layer 3. The first electrode 2 is formed by alternately laminating a plurality layers of first light transmitting conductive films 21 with a low carrier concentration and a plurality layers of second light transmitting conductive films 22 with a high carrier concentration. Accordingly, while a laminated film of the light transmitting conductive films functions as an electrode on a light receiving surface side of a solar battery cell, an infrared reflection effect can be obtained by utilizing the refractive index difference between the first light transmitting conductive films 21 and the second light transmitting conductive films 22 in an infrared region.

Description

本発明は、太陽電池および太陽電池モジュールに関する。   The present invention relates to a solar cell and a solar cell module.

近年、環境問題に対する意識の高まりから、太陽光を直接電気エネルギーに変換することのできる太陽電池はクリーンエネルギーとして急速に普及している。一般的に、太陽電池モジュールは、太陽光が表面のガラス面から入射し、光電変換素子とその両面に配置される２つの電極から構成される複数の太陽電池セルに照射され電力が生起される。また、太陽電池セルの受光面側の電極には薄膜系の太陽電池を中心に光透過性と導電性を両立した導電性酸化物を利用した透光性電極が利用されている。   In recent years, solar cells capable of directly converting sunlight into electric energy have been rapidly spread as clean energy due to an increase in awareness of environmental problems. In general, in a solar cell module, sunlight is incident from a glass surface, and is irradiated to a plurality of solar cells composed of a photoelectric conversion element and two electrodes disposed on both surfaces thereof to generate electric power. . In addition, a light-transmitting electrode using a conductive oxide that has both light transmittance and conductivity is used mainly for a thin-film solar cell as the electrode on the light-receiving surface side of the solar battery cell.

一般に、太陽電池は温度上昇が発生すると、開放電圧が低下し発電効率が低下することが知られている。さらに、温度の高いあるいは温度変化の激しい環境下で使用し続けることにより太陽電池モジュールの特性が劣化するという問題が生じる。一方で、太陽電池モジュールは日中の日光照射や外気温の上昇により表面温度が６０度以上の高温に達することもあるため、この温度上昇を抑制することが総合的な発電量の増加につながる。このため、太陽電池モジュールの温度上昇を抑制する種々の方法が検討されており、なかでもランニングコストのかからないものとして、太陽電池の温度上昇の原因となる赤外線領域の光のうち、波長が長く光電変換素子が光電変換に利用できない光を受光面側で遮断する構造が提案されている。このとき、光電変換素子の吸収係数が高く、太陽光スペクトル密度の高い可視光線や近紫外線の透過率を低下させないことは当然であるが、近年は太陽電池吸収係数の低い近赤外線の利用効率を高めることが変換効率の向上につながっており、光電変換に利用可能である全ての波長域(以下、有効波長域と呼ぶ)での透過率を高く維持したまま、有効波長域より長波長側の赤外線を反射することが重要となる。   In general, it is known that when a temperature rise occurs in a solar cell, the open circuit voltage decreases and the power generation efficiency decreases. Furthermore, there is a problem that the characteristics of the solar cell module deteriorate due to continued use in an environment where the temperature is high or the temperature changes rapidly. On the other hand, the surface temperature of solar cell modules may reach a high temperature of 60 ° C. or more due to daytime sunlight irradiation or an increase in outside air temperature. Therefore, suppressing this temperature increase leads to an increase in total power generation. . For this reason, various methods for suppressing the temperature rise of the solar cell module have been studied. Among them, light that has a long wavelength out of the light in the infrared region, which causes the temperature rise of the solar cell, is considered to have no running cost. A structure in which light that cannot be used for photoelectric conversion by the conversion element is blocked on the light receiving surface side has been proposed. At this time, it is natural that the photoelectric conversion element has a high absorption coefficient and does not decrease the transmittance of visible light or near ultraviolet light having a high solar spectrum density. Increasing the conversion leads to an improvement in conversion efficiency, while maintaining a high transmittance in all wavelength regions that can be used for photoelectric conversion (hereinafter referred to as the effective wavelength region), It is important to reflect infrared rays.

また、光電変換に利用可能な波長は太陽電池の種類や構造によって異なっており、種々の太陽電池に対応するためには、赤外線の反射特性の波長依存性を容易に最適化できる構造が好ましい。   In addition, the wavelength that can be used for photoelectric conversion varies depending on the type and structure of the solar cell, and in order to cope with various types of solar cells, a structure that can easily optimize the wavelength dependence of the infrared reflection characteristics is preferable.

従来、可視光域の光に対する透過率を確保しつつ赤外線を反射する技術には、金属薄膜や導電性酸化物のプラズマ反射、光学多層膜を利用したものがある。しかし、金属薄膜による赤外線反射技術では、高い熱線反射率を容易に得ることができるが、反射特性の波長依存性が比較的平坦なために、高い熱線反射率を実現するためには可視光透過率を犠牲にする必要がある。一方で、導電性酸化物のプラズマ反射では、膜中の自由電子によるプラズマ振動が生じてプラズマ周波数より長波長の光が全反射される現象を利用する。このプラズマ周波数ωｐは、Ｎをキャリア（自由電子）濃度、ｅを電子の電荷量、εを誘電率としたとき、数式（１）で表されキャリア濃度Ｎの関数となる。 Conventionally, techniques for reflecting infrared rays while ensuring transmittance for light in the visible light range include those utilizing metal thin films, plasma reflection of conductive oxides, and optical multilayer films. However, infrared reflection technology using a metal thin film can easily obtain high heat ray reflectivity, but the wavelength dependence of the reflection characteristics is relatively flat. It is necessary to sacrifice the rate. On the other hand, plasma reflection of a conductive oxide uses a phenomenon in which plasma oscillation is caused by free electrons in the film and light having a wavelength longer than the plasma frequency is totally reflected. The plasma frequency omega p is, N carriers (free electrons) concentration, electron charge quantity e, when was the dielectric constant epsilon, the function of the represented carrier concentration N in Equation (1).

Figure 2015141941
Figure 2015141941

このことから、導電性酸化物のキャリア濃度を増加させ、プラズマ周波数を近赤外線へと移動させることで赤外線を反射することが可能となる。しかし、従来のプラズマ反射による赤外線反射は、原理的に波長３μｍ以上といった比較的長波長側の赤外線反射に有用であるが、短波長側の赤外線については反射率を高めにくいため不向きである。日射に含まれる赤外線のエネルギー密度は短波長側ほど大きいので、プラズマ反射による赤外線反射の利用のみでは高い日射熱遮蔽効果を得ることは困難であった。また、プラズマ周波数付近の光はプラズマ吸収が生じるため吸収率が増加する。このため、プラズマ周波数を有効波長域付近に移動させると有効波長域における吸収増加や高エネルギーの近赤外線の吸収により膜自体が発熱してしまうという問題もある。   Therefore, it is possible to reflect infrared rays by increasing the carrier concentration of the conductive oxide and moving the plasma frequency to near infrared rays. However, conventional infrared reflection by plasma reflection is useful in principle for infrared reflection on a relatively long wavelength side such as a wavelength of 3 μm or more, but it is not suitable for infrared rays on a short wavelength side because it is difficult to increase the reflectance. Since the energy density of infrared rays contained in solar radiation is larger at shorter wavelengths, it is difficult to obtain a high solar heat shielding effect only by using infrared reflection by plasma reflection. Also, light absorption near the plasma frequency increases because the absorption of plasma occurs. For this reason, when the plasma frequency is moved to the vicinity of the effective wavelength region, there is a problem that the film itself generates heat due to increased absorption in the effective wavelength region and absorption of high energy near infrared rays.

そこで、特許文献１では上記の導電性酸化物や金属等の赤外線を遮蔽する透過波長選択剤を樹脂中に分散させた赤外線遮蔽層が提案されている。この赤外線遮蔽層において、透過波長選択剤として粉末状の微粒子を使用することで層状に全面に成膜した場合と比較し、高い可視光透過性を有しつつ赤外線を反射することができる。しかしながら、このような樹脂と微粒子とからなる系においても、一般に有効波長域の光に対する透過率を確保しつつ赤外線を反射するという２つの課題は相反する要求である。例えば、特許文献１の太陽電池封止材においては、確かに樹脂中に透過波長選択剤が存在することにより、赤外線の太陽電池素子への到達が抑制されることになるが、これと同時に、透過波長選択剤による有効波長域の光の散乱や吸収を生じ、有効波長域の光が遮蔽されることにもなる。実際、このような太陽電池封止材において、透過波長選択剤の添加量が少ないと、十分な赤外線反射効果が得られず、一方で、十分な赤外線発現効果が得られる程度まで透過波長選択剤を添加すると、有効波長域の光が遮蔽されて発電効率が低下する結果となる。   Therefore, Patent Document 1 proposes an infrared shielding layer in which a transmission wavelength selection agent that shields infrared rays such as the above-described conductive oxides and metals is dispersed in a resin. In this infrared ray shielding layer, infrared rays can be reflected while having high visible light transmittance as compared with the case where a film is formed on the entire surface by using powdery fine particles as a transmission wavelength selection agent. However, even in such a system composed of resin and fine particles, the two problems of reflecting infrared rays while ensuring the transmittance for light in the effective wavelength region are generally contradictory requirements. For example, in the solar cell sealing material of Patent Document 1, the presence of a transmission wavelength selection agent in the resin surely suppresses the arrival of infrared rays into the solar cell element. Scattering and absorption of light in the effective wavelength region by the transmission wavelength selective agent are caused, and the light in the effective wavelength region is also shielded. In fact, in such a solar cell encapsulant, if the addition amount of the transmission wavelength selective agent is small, a sufficient infrared reflection effect cannot be obtained, but on the other hand, the transmission wavelength selective agent is obtained to the extent that a sufficient infrared expression effect can be obtained. If is added, light in the effective wavelength region is shielded, resulting in a decrease in power generation efficiency.

また、特許文献２では上記のような散乱を減少させるため微粒子をフィラー状にし、透過波長選択剤による吸収を低減するために金属酸化物被覆合成マイカなどの干渉顔料を用いることで高い可視光透過率と効果的な赤外線反射の両立を目指しているが、この課題が十分に解消されているとはいえない。   Further, in Patent Document 2, high visible light transmission is achieved by forming fine particles into a filler to reduce the scattering as described above, and using an interference pigment such as a metal oxide-coated synthetic mica to reduce absorption by the transmission wavelength selective agent. The goal is to achieve both effective and effective infrared reflection, but this problem has not been fully resolved.

一方で、光学多層膜による反射は、その特徴である高い透過率と急峻な遷移特性を利用することで、プラズマ反射や金属薄膜によるものと比較して高い可視光透過率と効果的な赤外線反射を両立することが可能である。   On the other hand, the reflection by the optical multilayer film uses the high transmittance and steep transition characteristics that are the characteristics of the reflection, so that the visible light transmittance and the effective infrared reflection are higher than those by the plasma reflection or metal thin film. It is possible to achieve both.

特許文献３では屈折率の異なる２種類の層からなる多層膜を形成することで、有効波長域において透過率を高めつつ赤外線領域を反射する太陽電池用の基板が記載されている。   Patent Document 3 describes a solar cell substrate that reflects an infrared region while increasing transmittance in an effective wavelength region by forming a multilayer film composed of two types of layers having different refractive indexes.

特開平１０−２７０７３０号公報Japanese Patent Laid-Open No. 10-270730 特開２０１０−２１２３８１号公報JP 2010-212381 A 特開２００７−２５１１１４号公報JP 2007-251114 A

しかしながら、上記特許文献３に記載された技術によれば、透光性導電膜の他に、新たに所定の屈折率を有する２種類以上の材料層を設けなければならないことに加え、多層膜の層数が少ないと赤外線と同時に可視光域にも反射が生じてしまう。このため、太陽電池の有効波長域全体で高い透過率を得るためには少なくとも１０層以上の異なる膜厚の多層膜を設計および形成する必要があり、コストの増加や生産性の低下を招くといった問題があった。   However, according to the technique described in Patent Document 3, in addition to the translucent conductive film, two or more kinds of material layers having a predetermined refractive index must be newly provided. When the number of layers is small, reflection occurs in the visible light region simultaneously with infrared rays. For this reason, in order to obtain a high transmittance in the entire effective wavelength range of the solar cell, it is necessary to design and form a multilayer film having at least 10 different thicknesses, resulting in an increase in cost and a decrease in productivity. There was a problem.

本発明は上記に鑑みてなされたものであり、経済性や生産性を損なうことなく、太陽電池モジュールに入射した光のうち、太陽電池が利用可能な波長の光を有効に取り込む機能と、太陽電池モジュールの温度上昇をもたらす赤外線を反射する機能とを兼ね備えた太陽電池モジュールを得ることを目的とする。   The present invention has been made in view of the above, and has a function of effectively capturing light having a wavelength that can be used by a solar cell, out of light incident on the solar cell module, without impairing economical efficiency and productivity, It aims at obtaining the solar cell module which has the function to reflect the infrared rays which bring about the temperature rise of a battery module.

上述した課題を解決し、目的を達成するため、本発明は、第１の電極と、第２の電極とによって半導体層からなる光電変換層を挟んだ太陽電池であって、第１および第２の電極のうち、受光面側に配される電極が、第１の透光性導電膜と、第１の透光性導電膜よりも高キャリア濃度を有する第２の透光性導電膜とが交互に積層された３層以上の多層膜で構成されたことを特徴とする。   In order to solve the above-described problems and achieve the object, the present invention is a solar cell in which a photoelectric conversion layer composed of a semiconductor layer is sandwiched between a first electrode and a second electrode, and the first and second Among the electrodes, the electrode disposed on the light-receiving surface side includes a first light-transmitting conductive film and a second light-transmitting conductive film having a higher carrier concentration than the first light-transmitting conductive film. It is composed of a multilayer film of three or more layers laminated alternately.

本発明によれば、第１および第２の透光性導電膜の積層膜が太陽電池の受光面側の電極として機能しつつ、低キャリア濃度の第１の透光性導電膜と高キャリア濃度の第２の透光性導電膜の赤外線領域における屈折率差を利用し、赤外線反射効果を得ることができる。一方で、太陽電池が利用可能な可視光線や近紫外線領域では屈折率差が小さく、透光性導電膜の積層膜による反射がないため、高い透過率を得ることができると同時に積層膜の構成を簡略化することができ、経済性や生産性を損なわない。   According to the present invention, the laminated film of the first and second light-transmitting conductive films functions as an electrode on the light-receiving surface side of the solar cell, and the first light-transmitting conductive film having a low carrier concentration and the high carrier concentration. An infrared reflection effect can be obtained by utilizing the refractive index difference in the infrared region of the second translucent conductive film. On the other hand, the refractive index difference is small in the visible light and near-ultraviolet region where solar cells can be used, and there is no reflection by the laminated film of the light-transmitting conductive film, so that high transmittance can be obtained and at the same time the structure of the laminated film Can be simplified without impairing economy and productivity.

図１は、実施の形態１に係る太陽電池の断面図である。1 is a cross-sectional view of the solar cell according to Embodiment 1. FIG. 図２は、実施の形態１に係る太陽電池の製造工程を示すフローチャートである。FIG. 2 is a flowchart showing a manufacturing process of the solar cell according to Embodiment 1. 図３は、実施の形態１に係る太陽電池モジュールの断面図である。FIG. 3 is a cross-sectional view of the solar cell module according to Embodiment 1. 図４は、実施の形態２における第１の電極にテクスチャが形成された太陽電池の断面図である。FIG. 4 is a cross-sectional view of a solar cell in which a texture is formed on the first electrode in the second embodiment. 図５は、実施の形態２に係る太陽電池の製造工程を示すフローチャートである。FIG. 5 is a flowchart showing a manufacturing process of the solar cell according to the second embodiment. 図６は、キャリア濃度の異なる２種類のＺｎＯ透光性導電膜の屈折率の波長依存性を示したグラフである。FIG. 6 is a graph showing the wavelength dependence of the refractive index of two types of ZnO translucent conductive films having different carrier concentrations. 図７は、実施の形態２における導電性酸化物の薄膜多層膜の反射率の波長依存性の一例を計算した結果を示したグラフである。FIG. 7 is a graph showing a result of calculating an example of the wavelength dependence of the reflectance of the conductive oxide thin film multilayer film according to the second embodiment. 図８は、従来の屈折率の波長依存性のない膜による薄膜多層膜の反射率の波長依存性の一例を計算した結果を示したグラフである。FIG. 8 is a graph showing a result of calculating an example of the wavelength dependence of the reflectance of the thin film multilayer film by the conventional film having no wavelength dependence of the refractive index. 図９は、ＺｎＭｇＯ透光性導電膜とＺｎＯ透光性導電膜の屈折率の波長依存性を示したグラフである。FIG. 9 is a graph showing the wavelength dependence of the refractive index of the ZnMgO translucent conductive film and the ZnO translucent conductive film. 図１０は、実施の形態４における導電性酸化物の薄膜多層膜の反射率の波長依存性の一例を計算した結果を示したグラフである。FIG. 10 is a graph showing a result of calculating an example of the wavelength dependence of the reflectance of the conductive oxide thin film multilayer film in the fourth embodiment. 図１１は、実施の形態５における基板表面にテクスチャが形成された太陽電池の断面図である。FIG. 11 is a cross-sectional view of a solar cell in which a texture is formed on the substrate surface in the fifth embodiment. 図１２は、実施の形態５に係る太陽電池の製造工程を示すフローチャートである。FIG. 12 is a flowchart showing a manufacturing process of the solar cell according to the fifth embodiment. 図１３は、実施の形態６における太陽電池の断面図である。FIG. 13 is a cross-sectional view of the solar cell in the sixth embodiment. 図１４は、実施例および比較例の太陽電池の特性を測定した結果を示す表図である。FIG. 14 is a table showing the results of measuring the characteristics of the solar cells of Examples and Comparative Examples. 図１５は、実施例および比較例の太陽電池の特性を測定した結果を示す表図である。FIG. 15 is a table showing the results of measuring the characteristics of the solar cells of Examples and Comparative Examples.

以下に、本発明にかかる太陽電池およびその製造方法の実施の形態を図面に基づいて詳細に説明する。なお、この実施の形態によりこの発明が限定されるものではなく、本発明の要旨を逸脱しない範囲において適宜変更可能である。また、以下に示す図面においては、理解の容易のため、層の厚みと幅との関係や各層の厚みの比率などは現実のものとは異なる。かかる太陽電池セルが太陽電池（素子）の最小単位であり、太陽電池セルが１個または複数個集まって太陽電池が構成される。本発明の太陽電池は、太陽電池セル１個であってもよいし、太陽電池セルを１個または複数個電気的に直列または並列に結線し、封止してなる太陽電池モジュールであってもよい。   Embodiments of a solar cell and a method for manufacturing the solar cell according to the present invention will be described below in detail with reference to the drawings. In addition, this invention is not limited by this embodiment, In the range which does not deviate from the summary of this invention, it can change suitably. In the drawings shown below, for easy understanding, the relationship between the thickness and width of the layers, the ratio of the thicknesses of the layers, and the like are different from the actual ones. Such a solar battery cell is the minimum unit of the solar battery (element), and one or a plurality of solar battery cells gather to constitute a solar battery. The solar battery of the present invention may be a single solar battery cell or a solar battery module in which one or a plurality of solar battery cells are electrically connected in series or in parallel and sealed. Good.

実施の形態１．
実施の形態１による太陽電池について、図１を基に説明する。本実施の形態による太陽電池は、太陽光Ｌが入射する受光面Ａ側から透光性基板１上に、第１の透光性導電膜２１（２１ａ，２１ｂ）と、第１の透光性導電膜２１よりも高いキャリア濃度を有する第２の透光性導電膜２２（２２ａ，２２ｂ）とが交互に積層された４層膜からなる第１の電極２と、光電変換層３と、裏面電極である第２の電極４とがこの順に積層された構成となっている。第１の電極は、低キャリア濃度である第１の透光性導電膜２１と高キャリア濃度である第２の透光性導電膜２２が交互に積層されている。 Embodiment 1 FIG.
The solar cell according to Embodiment 1 will be described with reference to FIG. The solar cell according to the present embodiment has a first light-transmitting conductive film 21 (21a, 21b) and a first light-transmitting property on the light-transmitting substrate 1 from the light-receiving surface A side on which sunlight L is incident. First electrode 2 composed of a four-layer film in which second light-transmitting conductive films 22 (22a, 22b) having higher carrier concentration than conductive film 21 are alternately stacked, photoelectric conversion layer 3, and back surface The second electrode 4 as an electrode is laminated in this order. In the first electrode, the first light-transmitting conductive film 21 having a low carrier concentration and the second light-transmitting conductive film 22 having a high carrier concentration are alternately stacked.

第１および第２の透光性導電膜のうち、キャリア濃度の高い、第２の透光性導電膜２２ｂが、光電変換層３に当接する側に配されている。また、第１および第２の透光性導電膜は、光学膜厚が等しい。本実施の形態では、テクスチャ構造を形成していないため、光電変換層３との屈折率差が大きくなるように、高キャリア濃度の第２の透光性導電膜２２を光電変換層３側に配置した方が好ましい。一方、受光面側にテクスチャ構造を形成した場合にはもう１層、低キャリア濃度の第１の透光性導電膜を光電変換層３との間に配するのが望ましい。   Of the first and second light-transmitting conductive films, the second light-transmitting conductive film 22 b having a high carrier concentration is disposed on the side in contact with the photoelectric conversion layer 3. The first and second light-transmitting conductive films have the same optical film thickness. In this embodiment, since the texture structure is not formed, the second light-transmitting conductive film 22 having a high carrier concentration is placed on the photoelectric conversion layer 3 side so that the refractive index difference with the photoelectric conversion layer 3 is increased. It is preferable to arrange them. On the other hand, when a texture structure is formed on the light receiving surface side, it is desirable to arrange another layer, a first light-transmitting conductive film having a low carrier concentration, between the photoelectric conversion layer 3 and the first light-transmitting conductive film.

次に、本実施の形態の太陽電池を構成する各部材について説明する。   Next, each member which comprises the solar cell of this Embodiment is demonstrated.

透光性基板１は透光性を有する絶縁性の材料からなり、その上に各薄膜を堆積することが可能であれば特に制限はなく、耐候性および機械的強度の点で、ガラスやポリカーボネート等の樹脂からなる基板が好適に用いられる。   The translucent substrate 1 is made of an insulating material having translucency, and is not particularly limited as long as each thin film can be deposited thereon. From the viewpoint of weather resistance and mechanical strength, glass or polycarbonate is used. A substrate made of such a resin is preferably used.

光電変換層３は、ｐｎ接合またはｐｉｎ接合を有し、入射する光により発電を行う薄膜半導体層が１層以上積層されて構成される。光電変換層３がＳｉ系薄膜からなる場合には、光電変換層３として非晶質Ｓｉ薄膜や微結晶Ｓｉ薄膜等が用いられる。非晶質Ｓｉ薄膜は、通常水素で未結合手が終端された水素化非晶質Ｓｉと呼ばれ、微結晶Ｓｉは部分的に非晶質Ｓｉを含んだ微細な結晶質Ｓｉを含んだ薄膜である。そのほか、ＣＩＳ（銅(Ｃｏｐｐｅｒ)、インジウム(Ｉｎｄｉｕｍ)、セレン(Ｓｅｌｅｎｉｕｍ)を主成分として含むもの）やＣＩＧＳ（銅、インジウム、ガリウム(Ｇａｌｌｉｕｍ)、セレンを主成分として含むもの）、ＧａＡｓ（ガリウム砒素）、ＣｄＴｅ（カドミウムテルル）等の化合物系材料、有機系材料などが用いられる。複数の薄膜半導体層を積層して光電変換層３を構成する場合には、バンドギャップの異なる複数の薄膜半導体層を積層することで、より幅広い光スペクトルを高効率に光電変換可能な構成とすることができる。なお、複数の薄膜半導体層が積層されて光電変換層３が構成される場合には、異なる薄膜半導体層間にＳｎＯ2、ＺｎＯ、ＩＴＯ、ＳｉＯ2、ＴｉＯ2などの導電性酸化物材料などの中間層を挿入して、異なる薄膜半導体層間の電気的、光学的接続を改善してもよい。 The photoelectric conversion layer 3 has a pn junction or a pin junction, and is configured by laminating one or more thin film semiconductor layers that generate power by incident light. When the photoelectric conversion layer 3 is made of a Si-based thin film, an amorphous Si thin film, a microcrystalline Si thin film, or the like is used as the photoelectric conversion layer 3. An amorphous Si thin film is usually called hydrogenated amorphous Si in which dangling bonds are terminated with hydrogen, and microcrystalline Si is a thin film containing fine crystalline Si partially containing amorphous Si. It is. In addition, CIS (containing copper, indium, selenium as main components), CIGS (containing copper, indium, gallium, selenium as main components), GaAs (gallium arsenide) ), Compound materials such as CdTe (cadmium tellurium), organic materials, and the like are used. When the photoelectric conversion layer 3 is configured by stacking a plurality of thin film semiconductor layers, a configuration in which a wider optical spectrum can be photoelectrically converted with high efficiency by stacking a plurality of thin film semiconductor layers having different band gaps. be able to. When a plurality of thin film semiconductor layers are stacked to constitute the photoelectric conversion layer 3, an intermediate layer of a conductive oxide material such as SnO 2 , ZnO, ITO, SiO 2 , or TiO 2 is provided between different thin film semiconductor layers. Layers may be inserted to improve electrical and optical connections between different thin film semiconductor layers.

裏面Ｂ側に形成される裏面電極である第２の電極４は、導電性を有する材料で構成され、Ａｇ、Ａｌ、Ｎｉ、Ｃｕ等の金属材料や半田等の合金材料、導電性酸化物材料、カーボン材料およびこれらをフィラーとして含む導電性樹脂材料、もしくはこれらの組合せから適宜選択される。   The second electrode 4 that is the back electrode formed on the back surface B side is made of a conductive material, such as a metal material such as Ag, Al, Ni, or Cu, an alloy material such as solder, or a conductive oxide material. , Carbon material and conductive resin material containing these as fillers, or a combination thereof.

太陽電池モジュール１００を構成する場合には、図３に示すように、透光性基板１上に複数の第１の電極２が配列され、この第１の電極２上に光電変換層３と、裏面側の透光性導電膜４Ｐと、第２の電極４とが順次積層されている。そしてこの第２の電極４上に保護層（図示せず）として裏面側カバー層が形成されており、端部の太陽電池セルの第１および第２の電極２，４からそれぞれリードＲ1，Ｒ2が導出されている。裏面側の透光性導電膜４Ｔは、他の図では省略している。裏面側カバー層としては、水分を透過しないように、アルミ箔を挟持した耐候性を有するフッ素系樹脂シートや、アルミナまたはシリカを蒸着したポリエチレンテレフタレートシートなどが好適に用いられる。   When the solar cell module 100 is configured, as shown in FIG. 3, a plurality of first electrodes 2 are arranged on the translucent substrate 1, and the photoelectric conversion layer 3 and the first electrode 2 are arranged on the first electrode 2. The light-transmitting conductive film 4P on the back side and the second electrode 4 are sequentially stacked. A back cover layer is formed on the second electrode 4 as a protective layer (not shown), and leads R1, R2 from the first and second electrodes 2, 4 of the solar cell at the end, respectively. Has been derived. The translucent conductive film 4T on the back side is omitted in the other drawings. As the back surface side cover layer, a fluorine resin sheet having weather resistance sandwiching an aluminum foil, a polyethylene terephthalate sheet vapor-deposited with alumina or silica, or the like is suitably used so as not to transmit moisture.

本実施の形態においては、第１の電極２は、低キャリア濃度を有する第１の透光性導電膜２１と高キャリア濃度を有する第２の透光性導電膜２２とが交互に計５層積層された導電性の多層膜である。なお、積層数が３層より少ない場合には光学干渉による赤外線の反射率向上効果が十分に得られず、積層数が多すぎると膜厚が増加し透過率の低下を招くことに加え、コストや生産性が悪化することから積層数は３〜７層とすることが好ましい。   In the present embodiment, the first electrode 2 includes a total of five layers of a first light-transmitting conductive film 21 having a low carrier concentration and a second light-transmitting conductive film 22 having a high carrier concentration. It is a laminated conductive multilayer film. In addition, when the number of stacked layers is less than 3, the effect of improving the reflectance of infrared rays due to optical interference cannot be obtained sufficiently. When the number of stacked layers is too large, the film thickness increases and the transmittance decreases, and the cost decreases. And the number of stacked layers is preferably 3 to 7 because productivity deteriorates.

このように本実施の形態によれば、透光性導電膜の積層膜が太陽電池セル受光面側の電極として機能しつつ、低キャリア濃度である第１の透光性導電膜と高キャリア濃度である第２の透光性導電膜の赤外線領域における屈折率差を利用し、赤外線を選択的に反射することができる。   As described above, according to the present embodiment, the laminated film of the light-transmitting conductive film functions as an electrode on the light-receiving surface side of the solar battery cell, and the first light-transmitting conductive film having a low carrier concentration and the high carrier concentration. It is possible to selectively reflect infrared rays by utilizing the difference in refractive index in the infrared region of the second translucent conductive film.

次に、本実施の形態の太陽電池の製造方法について説明する。図２はその製造工程を示すフローチャート図である。本実施の形態では、まず、ガラス基板からなる透光性基板１表面に、第１の透光性導電膜２１ａ、第２の透光性導電膜２２ａ、第１の透光性導電膜２１ｂ、第２の透光性導電膜２２ｂ、第１の透光性導電膜２１ｃ、少なくとも１組のｐｉｎ構造を有する光電変換層３、および裏面電極である第２の電極４を順に積層する。   Next, the manufacturing method of the solar cell of this Embodiment is demonstrated. FIG. 2 is a flowchart showing the manufacturing process. In the present embodiment, first, a first light-transmitting conductive film 21a, a second light-transmitting conductive film 22a, a first light-transmitting conductive film 21b, The second translucent conductive film 22b, the first translucent conductive film 21c, the photoelectric conversion layer 3 having at least one pair of pin structures, and the second electrode 4 that is the back electrode are sequentially stacked.

まず、透光性基板１としてガラス基板を用意する。そしてこの透光性基板１上に、透光性導電膜から成る第１の電極２を形成する(ステップＳ１)。   First, a glass substrate is prepared as the translucent substrate 1. Then, a first electrode 2 made of a translucent conductive film is formed on the translucent substrate 1 (step S1).

ここで第１の電極２を形成する工程は、第１の透光性導電膜２１ａを形成し、次いで、第２の透光性導電膜２２ａ、第１の透光性導電膜２１ｂ、第２の透光性導電膜２２ｂ、第１の透光性導電膜２１ｃと、順次積層する(ステップＳ１１〜Ｓ１５)。ここではスパッタリング工程において２種類のターゲットを交互に成膜することで各層のキャリア濃度を変化させる。第１の透光性導電膜２１ａ，第１の透光性導電膜２１ｂ，第１の透光性導電膜２１ｃはＺｎＯ：Ａｌ（０．５ｗｔ％）である。また、第２の透光性導電膜２２ａ，第２の透光性導電膜２２ｂはＺｎＯ：Ａｌ（３．０ｗｔ％）である。   Here, in the step of forming the first electrode 2, the first light-transmitting conductive film 21a is formed, and then the second light-transmitting conductive film 22a, the first light-transmitting conductive film 21b, and the second. The transparent conductive film 22b and the first transparent conductive film 21c are sequentially stacked (steps S11 to S15). Here, the carrier concentration of each layer is changed by alternately forming two types of targets in the sputtering process. The first translucent conductive film 21a, the first translucent conductive film 21b, and the first translucent conductive film 21c are made of ZnO: Al (0.5 wt%). The second light-transmitting conductive film 22a and the second light-transmitting conductive film 22b are made of ZnO: Al (3.0 wt%).

この後、１組のｐｉｎ構造を有する光電変換層３を積層する(ステップＳ２)。   Thereafter, the photoelectric conversion layer 3 having a pair of pin structures is stacked (step S2).

最後に、裏面電極としての第２の電極４を積層する(ステップＳ３)。   Finally, the second electrode 4 as the back electrode is stacked (step S3).

本実施の形態では、各透光性導電膜の光学膜厚を等しくすることで各透光性導電膜界面における反射光の位相を揃えることで所望の波長で高い反射特性を得ることができる。   In the present embodiment, it is possible to obtain high reflection characteristics at a desired wavelength by equalizing the optical film thickness of each translucent conductive film so as to align the phase of reflected light at each translucent conductive film interface.

実施の形態２．
また、一般に実施の形態１のようなスーパーストレート型の薄膜太陽電池の受光面電極である第１の電極２は、図４に示すように、光電変換層３との界面に凹凸構造を形成したテクスチャ構造２Ｔを有することが好ましい。このテクスチャ構造により入射光を散乱させ、光電変換層３での光利用効率を高めることができる。他部については前記実施の形態１と同様であるため、ここでは説明を省略する。 Embodiment 2. FIG.
In general, the first electrode 2 that is the light-receiving surface electrode of the super-straight type thin film solar cell as in Embodiment 1 has an uneven structure at the interface with the photoelectric conversion layer 3 as shown in FIG. It is preferable to have a texture structure 2T. Incident light can be scattered by this texture structure, and the light use efficiency in the photoelectric conversion layer 3 can be improved. Since other parts are the same as those in the first embodiment, description thereof is omitted here.

なお、第１の電極２のうち、最も光電変換層３側に位置する第１の透光性導電膜２１ｃＴの光電変換層３との界面にテクスチャ２Ｔを形成している。テクスチャ形成には数百ｎｍから数μｍ程度と、他の積層膜と比較して厚い膜を形成する必要があるため、膜の吸収特性の影響が大きくなる。よって、第１の電極２の最も光電変換層３側は吸収の小さい低キャリア濃度層である第１の透光性導電膜２１ｃＴとすることが好ましい。本実施の形態では第２の電極４の裏面Ｂ側にもテクスチャ４Ｔが形成されている。   In addition, the texture 2T is formed in the interface with the photoelectric converting layer 3 of the 1st translucent conductive film 21cT located among the 1st electrodes 2 at the most photoelectric converting layer 3 side. For texture formation, it is necessary to form a film having a thickness of several hundred nm to several μm, which is thicker than other laminated films, so that the influence of the absorption characteristics of the film becomes large. Therefore, it is preferable that the photoelectric conversion layer 3 side of the first electrode 2 be the first light-transmitting conductive film 21cT that is a low carrier concentration layer with low absorption. In the present embodiment, the texture 4T is also formed on the back surface B side of the second electrode 4.

次に、本実施の形態の太陽電池の製造方法について説明する。図５はその製造工程を示すフローチャート図である。本実施の形態では、実施の形態１の場合と異なるのは、第１の電極２を構成する５層の多層膜を順次形成した後、最上層の第１の透光性導電膜２１ｃ形成後に第１の透光性導電膜２１ｃの表面にテクスチャを形成する工程Ｓ１６を実施することを特徴とするものである。この後は前記実施の形態１と同様である。   Next, the manufacturing method of the solar cell of this Embodiment is demonstrated. FIG. 5 is a flowchart showing the manufacturing process. In the present embodiment, the difference from the first embodiment is that after the multilayered film of five layers constituting the first electrode 2 is sequentially formed, the first light-transmitting conductive film 21c as the uppermost layer is formed. Step S16 of forming a texture on the surface of the first light-transmitting conductive film 21c is performed. The subsequent steps are the same as in the first embodiment.

つまり、ガラス基板からなる透光性基板１表面に、第１の透光性導電膜２１ａ、第２の透光性導電膜２２ａ、第１の透光性導電膜２１ｂ、第２の透光性導電膜２２ｂ、第１の透光性導電膜２１ｃを順に形成する（Ｓ１１からＳ１５）。こののち、少なくとも１組のｐｉｎ構造を有する光電変換層３を形成し（Ｓ２）、最後に第２の電極４である裏面電極を積層する（Ｓ３）。   That is, on the surface of the translucent substrate 1 made of a glass substrate, the first translucent conductive film 21a, the second translucent conductive film 22a, the first translucent conductive film 21b, and the second translucent film. The conductive film 22b and the first translucent conductive film 21c are formed in order (S11 to S15). After that, the photoelectric conversion layer 3 having at least one pair of pin structures is formed (S2), and finally the back electrode as the second electrode 4 is laminated (S3).

なお、実施の形態２ではテクスチャを形成する層を厚く形成する必要があること、テクスチャを形成するため光電変換層界面との反射が小さくなることから吸収の少ない低キャリア濃度の第１の透光性導電膜２１を光電変換層側に配置した方が好ましい。ただし、高キャリア濃度の第２の透光性導電膜２２の方が太陽電池に適したテクスチャ形状が得られる場合は、それを用いても良い。つまり、前記実施の形態では、第１の透光性導電膜２１ｃが光電変換層３側に位置するようにしたが、テクスチャ形成に適した成膜条件で薄く膜質の均一な膜を形成することができれば、最も光電変換層３側の第１の電極２は低キャリア濃度である第１の透光性導電膜に限らず、高いキャリア濃度である第２の透光性導電膜を用いてもよい。   Note that in Embodiment 2, the first light-transmitting light with a low carrier concentration with low absorption is required because the texture-forming layer needs to be formed thick and the reflection from the photoelectric conversion layer interface is small because the texture is formed. It is preferable to dispose the conductive film 21 on the photoelectric conversion layer side. However, when the texture shape suitable for the solar cell is obtained with the second light-transmitting conductive film 22 having a higher carrier concentration, it may be used. That is, in the above-described embodiment, the first translucent conductive film 21c is positioned on the photoelectric conversion layer 3 side. However, a thin film with uniform film quality is formed under film formation conditions suitable for texture formation. If possible, the first electrode 2 closest to the photoelectric conversion layer 3 is not limited to the first light-transmitting conductive film having a low carrier concentration, but a second light-transmitting conductive film having a high carrier concentration may be used. Good.

前述のように透光性導電膜は、式１で示したようにキャリア濃度に依存したプラズマ周波数をピークとする吸収を示すが同時にプラズマ周波数付近で屈折率が大きく低下する。図６にキャリア濃度の異なるＺｎＯの屈折率を示す。０．５ｗｔ％ＡｌをドープしたＺｎＯ、３．０ｗｔ％ＡｌをドープしたＺｎＯ（以下、それぞれＺｎＯ：Ａｌ（０．５ｗｔ％）、ＺｎＯ：Ａｌ（３．０ｗｔ％）と呼ぶ）の屈折率を曲線ａおよびｂで示す。これらの膜のホール効果測定法により測定されたキャリア濃度は２．７×１０20ｃｍ-3、７．５×１０20ｃｍ-3であった。両者の屈折率差は波長６００ｎｍにおいて０．１程度であるのに対し、波長１２００ｎｍにおいて０．５以上となり、赤外領域で顕著な屈折率差が得られることが明らかである。この屈折率差による反射を利用し、透光性導電膜の多層膜を形成することで従来の誘電体の薄膜多層膜と同様に反射光の位相を揃え、特定波長の反射率を高めることができる。受光面電極である第１の電極２の各層（テクスチャを形成する場合最も光電変換層側の層を除く）を反射させたい所望の波長λにおける光学膜厚（屈折率ｎ×膜厚ｄ）を制御することで光学干渉が生じる。特に、全ての層で透光性導電膜の光学膜厚がλ／４となる光路長に調整することで、各層で反射した光は位相を揃えて強め合うことで所望の波長λにおける反射率を容易に高めることができる。また、低キャリア濃度の第１の透光性導電膜２１と高キャリア濃度の第２の透光性導電膜２２の各層が周期構造を有していれば、それぞれの光学膜厚が異なっていても干渉による反射率向上効果が得られる。 As described above, the translucent conductive film exhibits absorption having a peak at the plasma frequency depending on the carrier concentration as shown in Equation 1, but at the same time, the refractive index is greatly reduced near the plasma frequency. FIG. 6 shows the refractive indexes of ZnO having different carrier concentrations. The refractive indexes of ZnO doped with 0.5 wt% Al and ZnO doped with 3.0 wt% Al (hereinafter referred to as ZnO: Al (0.5 wt%) and ZnO: Al (3.0 wt%), respectively) are curved. Indicated by a and b. The carrier concentrations of these films measured by the Hall effect measurement method were 2.7 × 10 20 cm −3 and 7.5 × 10 20 cm −3 . The refractive index difference between the two is about 0.1 at a wavelength of 600 nm, but is 0.5 or more at a wavelength of 1200 nm, and it is clear that a remarkable refractive index difference is obtained in the infrared region. By utilizing the reflection due to the difference in refractive index and forming a multilayer film of a light-transmitting conductive film, the phase of the reflected light can be aligned and the reflectance at a specific wavelength can be increased in the same manner as a conventional dielectric thin film multilayer film. it can. The optical film thickness (refractive index n × film thickness d) at a desired wavelength λ desired to reflect each layer of the first electrode 2 which is a light receiving surface electrode (excluding the layer closest to the photoelectric conversion layer when texture is formed). Control causes optical interference. In particular, by adjusting the optical path length so that the optical film thickness of the light-transmitting conductive film is λ / 4 in all layers, the light reflected by each layer is intensified by aligning the phases, and the reflectance at the desired wavelength λ Can be easily increased. Further, if each layer of the first light-transmitting conductive film 21 having a low carrier concentration and the second light-transmitting conductive film 22 having a high carrier concentration has a periodic structure, the optical film thicknesses thereof are different. Also, the effect of improving the reflectivity due to interference can be obtained.

このように、本実施の形態では、第１の電極で入射光を散乱させる機能を持たせつつ、各透光性導電膜の光学膜厚を等しくすることで各透光性導電膜界面における反射光の位相を揃えることで所望の波長で高い反射特性を得ることができる。   As described above, in this embodiment, the first electrode has a function of scattering incident light, and the optical film thickness of each translucent conductive film is made equal so that reflection at each translucent conductive film interface is performed. By aligning the phase of light, high reflection characteristics can be obtained at a desired wavelength.

図７にガラス基板上に低キャリア濃度の第１の透光性導電膜、高キャリア濃度の第２の透光性導電膜、低キャリア濃度の第１の透光性導電膜の順に交互に３層および５層積層したときに、ガラス基板から多層膜へと光を入射させたときに多層膜からガラス基板側へと反射される反射率の波長依存性の計算結果をそれぞれ曲線ａおよびｂで示す。最もガラス基板から遠い側の低キャリア濃度の第１の透光性導電膜は表面にテクスチャが形成されるため、第１の透光性導電膜と光電変換層界面における反射は小さく、さらに反射光が散乱されるため光学干渉効果に与える影響は無視できるほど少ないと考えられるため、出射側の媒質を第１の透光性導電膜とし、入射側の媒質は空気として計算した。また、屈折率差によって生じる反射特性を調べるため、膜による吸収は無いものとした。低キャリア濃度の第１の透光性導電膜および高キャリア濃度の第２の透光性導電膜の屈折率は前述の図６に示した値を用いた。波長１２００ｎｍで高反射率が得られるように膜厚を、低キャリア濃度の第１の透光性導電膜を１７２ｎｍ、高キャリア濃度の第２の透光性導電膜を２５２ｎｍと設定した。   In FIG. 7, the first light-transmitting conductive film having a low carrier concentration, the second light-transmitting conductive film having a high carrier concentration, and the first light-transmitting conductive film having a low carrier concentration are alternately arranged on the glass substrate in this order. When the layers and five layers are stacked, the calculation results of the wavelength dependence of the reflectance reflected from the multilayer film to the glass substrate side when light is incident from the glass substrate to the multilayer film are indicated by curves a and b, respectively. Show. Since the first translucent conductive film having the low carrier concentration on the side farthest from the glass substrate is textured on the surface, reflection at the interface between the first translucent conductive film and the photoelectric conversion layer is small, and reflected light is further reduced. Therefore, it is considered that the influence on the optical interference effect is negligibly small. Therefore, the medium on the emission side is calculated as the first light-transmitting conductive film, and the medium on the incident side is calculated as air. Further, in order to examine the reflection characteristics caused by the refractive index difference, it was assumed that there was no absorption by the film. The values shown in FIG. 6 were used for the refractive indexes of the first light-transmitting conductive film having a low carrier concentration and the second light-transmitting conductive film having a high carrier concentration. The film thickness was set to 172 nm for the first light-transmitting conductive film having a low carrier concentration and 252 nm for the second light-transmitting conductive film having a high carrier concentration so that a high reflectance was obtained at a wavelength of 1200 nm.

また、図８に比較のため、キャリア濃度が十分に低く屈折率が波長依存性がないと仮定した場合の多層膜の反射率の波長依存性の計算結果を示す。屈折率は透光性導電膜の波長１２００ｎｍにおける値を仮定し、膜厚も同じ値を用いた。両者を比較すると光学膜厚の一致する波長１２００ｎｍにおける反射率は同等の値が得られ、それぞれ曲線ａおよびｂに示すように３層構造で２０％、５層構造で５０％となっている。   For comparison, FIG. 8 shows the calculation result of the wavelength dependency of the reflectance of the multilayer film when it is assumed that the carrier concentration is sufficiently low and the refractive index is not wavelength dependent. The refractive index assumed the value in wavelength 1200nm of a translucent conductive film, and the film thickness used the same value. When both are compared, the reflectance at a wavelength of 1200 nm where the optical film thicknesses coincide is obtained, which is 20% for the three-layer structure and 50% for the five-layer structure, as shown by curves a and b, respectively.

図７および図８の比較から、本実施の形態の太陽電池では１２００ｎｍから波長が短くなるにつれて位相のずれが大きくなると同時に屈折率差が小さくなるため界面における反射も減少するため、従来の多層膜と比べて反射率が急峻に変化することがわかる。これは、従来の多層膜による反射では斜め入射時には光路長が変化するため反射ピークが短波長へとシフトするが、本実施の形態ではそのシフト量が小さくなり、入射角度依存性が小さくなることを同時に示している。１２００ｎｍよりも長波長側では従来の多層膜では位相がずれるため反射率が単調に低下するが、本実施の形態の太陽電池では屈折率差が大きくなることからある程度の波長までは反射率は増加傾向を示す。一方で短波長側に注目すると、従来の多層膜では太陽電池の有効波長域となる波長４００ｎｍ付近でも高い反射率を示している。これは１２００ｎｍで振幅の周期が１／２で反射光の位相が揃うのと同時に１周期ずれた周期が３／２となる波長、つまり設定波長の１／３の波長においても位相が揃うためである。また、これらの反射率の波長依存性は２層の屈折率を変化させても反射率が上下するだけで同様の特徴を示す。このことから従来の誘電体の多層膜では赤外線を反射しつつ、有効波長の透過率を高めるためには異なる膜厚を有した積層数の多い多層膜を形成する必要があり、そのために複雑な計算を行う必要があった。本実施の形態の太陽電池によれば多層膜界面の反射が赤外線領域のみで生じるため、積層数が少なく、簡易な構造の多層膜で赤外線領域のみを効率良く反射することができる。   From the comparison between FIG. 7 and FIG. 8, in the solar cell of the present embodiment, the phase shift increases as the wavelength decreases from 1200 nm, and at the same time, the refractive index difference decreases, so the reflection at the interface also decreases. It can be seen that the reflectance changes abruptly as compared with FIG. This is because the reflection peak shifts to a short wavelength because the optical path length changes at oblique incidence in the case of reflection by a conventional multilayer film, but in this embodiment, the shift amount becomes smaller and the incident angle dependency becomes smaller. At the same time. On the wavelength side longer than 1200 nm, the reflectance is monotonously lowered because of the phase shift in the conventional multilayer film, but the reflectance increases to a certain wavelength because the refractive index difference is large in the solar cell of the present embodiment. Show the trend. On the other hand, paying attention to the short wavelength side, the conventional multilayer film shows high reflectance even in the vicinity of a wavelength of 400 nm which is an effective wavelength region of the solar cell. This is because at 1200 nm, the amplitude period is ½ and the phase of the reflected light is aligned, and at the same time, the phase is also aligned at the wavelength where the period shifted by one period becomes 3/2, that is, the wavelength that is 1/3 of the set wavelength. is there. Further, the wavelength dependence of these reflectivities shows the same characteristics only when the reflectivity rises and falls even if the refractive index of the two layers is changed. Therefore, in order to increase the transmittance of the effective wavelength while reflecting the infrared rays in the conventional dielectric multilayer film, it is necessary to form a multilayer film having a large number of layers with different film thicknesses. It was necessary to make a calculation. According to the solar cell of the present embodiment, since the reflection at the multilayer film interface occurs only in the infrared region, the number of stacked layers is small, and only the infrared region can be efficiently reflected by the multilayer film having a simple structure.

低キャリア濃度の第１の透光性導電膜２１のキャリア濃度は０．２〜３．５×１０20ｃｍ-3とすることが好ましく、０．５〜３．０×１０20ｃｍ-3とすることがより好ましい。低キャリア濃度を有する第１の透光性導電膜２１のキャリア濃度が０．２×１０20ｃｍ-3よりも低い場合には、導電層として機能せず低抵抗の高キャリア濃度を有する第２の透光性導電膜２２との電気的接続が悪化するため、透光性導電膜の積層膜の抵抗が増加し、太陽電池の出力特性が低下する。一方、低キャリア濃度の第１の透光性導電膜２１のキャリア濃度が３．５×１０20ｃｍ-3よりも高い場合には赤外線領域での屈折率低下が大きくなり高キャリア濃度の第２の透光性導電膜２２との境界における反射が小さくなると同時に、第１の電極２全体での吸収が増加してしまう。 The carrier concentration of the first light-transmitting conductive film 21 having a low carrier concentration is preferably 0.2 to 3.5 × 10 20 cm −3 and 0.5 to 3.0 × 10 20 cm −3 . More preferably. When the carrier concentration of the first translucent conductive film 21 having a low carrier concentration is lower than 0.2 × 10 20 cm −3 , the second translucent layer does not function as a conductive layer and has a high carrier concentration with low resistance. Since the electrical connection with the transparent conductive film 22 deteriorates, the resistance of the laminated film of the transparent conductive film increases, and the output characteristics of the solar cell deteriorate. On the other hand, when the carrier concentration of the first light-transmitting conductive film 21 having a low carrier concentration is higher than 3.5 × 10 20 cm −3 , the refractive index decreases greatly in the infrared region, and the second carrier concentration having a high carrier concentration is obtained. At the same time, the reflection at the boundary with the transparent conductive film 22 is reduced, and at the same time, the absorption of the entire first electrode 2 is increased.

高キャリア濃度の第２の透光性導電膜２２のキャリア濃度は５．０〜１５．０×１０20ｃｍ-3とすることが好ましく、５．０〜１０．０×１０20ｃｍ-3とすることがより好ましい。高キャリア濃度の第２の透光性導電膜２２のキャリア濃度が５．０×１０20ｃｍ-3より低い場合には低キャリア濃度の第１の透光性導電膜２１との屈折率差による反射効果が得られにくくなり、一方で高キャリア濃度の第２の透光性導電膜２２のキャリア濃度が１５．０×１０20ｃｍ-3よりも高い場合にはプラズモン周波数に伴う吸収ピークが短波長へとシフトし、可視光線領域まで吸収が増加してしまう。また、高キャリア濃度の第２の透光性導電膜２２は近赤外線領域に吸収を生じるが、多層膜に使用される高キャリア濃度層は非常に薄く、低キャリア濃度の第１の透光性導電膜２１のみで第１の電極２を構成した場合に比べ、同様のシート抵抗を得るための電極層全体の膜厚が薄くてすむため、積層膜全体における吸収は低く抑えることができる。 Carrier concentration of the second transparent conductive film 22 of high carrier concentration is preferably set to 5.0~15.0 × 10 20 cm -3, and 5.0~10.0 × 10 20 cm -3 More preferably. When the carrier concentration of the second light-transmitting conductive film 22 having a high carrier concentration is lower than 5.0 × 10 20 cm −3 , the second light-transmitting conductive film 22 has a refractive index difference from that of the first light-transmitting conductive film 21 having a low carrier concentration. When the carrier concentration of the second translucent conductive film 22 having a high carrier concentration is higher than 15.0 × 10 20 cm −3 , the absorption peak associated with the plasmon frequency is short. It shifts to the wavelength and the absorption increases to the visible light region. The second light-transmitting conductive film 22 having a high carrier concentration absorbs in the near infrared region, but the high carrier concentration layer used for the multilayer film is very thin and the first light-transmitting property having a low carrier concentration is used. Compared with the case where the first electrode 2 is configured only by the conductive film 21, the entire electrode layer for obtaining the same sheet resistance can be thin, so that the absorption in the entire laminated film can be kept low.

このように第１および第２の透光性導電膜のキャリア濃度を上記範囲に規定することにより、透過性と導電性を維持しつつ、赤外線領域で屈折率差が十分に得られ、効率的に赤外線を反射することができる。   Thus, by defining the carrier concentration of the first and second translucent conductive films within the above range, a sufficient difference in refractive index can be obtained in the infrared region while maintaining transparency and conductivity, which is efficient. It can reflect infrared rays.

低キャリア濃度の第１の透光性導電膜２１および高キャリア濃度の第２の透光性導電膜２２は光透過性を有した導電膜であればよく、Ｉｎ2Ｏ3、ＺｎＯ、ＳｎＯ2などの導電性酸化物材料を単独もしくは混合して用いることができる。さらにこれらの材料に導電性のドーピング材料を添加することができる。例えば、導電性酸化物材料としてＩｎ2Ｏ3を用いた場合にはドーピング材料としてＺｎやＳｎ、Ｔｉ、Ｗ、Ｍｏ、Ｓｉ、Ｃｅなど、導電性酸化物材料としてＺｎＯを用いた場合にはドーピング材料としてＡｌやＧａ、Ｂ、Ｓｉ、Ｃなど、導電性酸化物材料としてＳｎＯ2を用いた場合にはドーピング材料としてＦなどが挙げられる。 The first light-transmitting conductive film 21 having a low carrier concentration and the second light-transmitting conductive film 22 having a high carrier concentration may be any light-transmitting conductive film. In 2 O 3 , ZnO, SnO 2 A conductive oxide material such as these can be used alone or in combination. Further, a conductive doping material can be added to these materials. For example, when In 2 O 3 is used as a conductive oxide material, doping is performed when ZnO is used as a conductive oxide material, such as Zn, Sn, Ti, W, Mo, Si, or Ce as a doping material. In the case where SnO 2 is used as the conductive oxide material, such as Al, Ga, B, Si, or C, the material may be F or the like.

低キャリア濃度の第１の透光性導電膜２１および高キャリア濃度の第２の透光性導電膜２２の成膜には既存のスパッタリング、プラズマＣＶＤ、低圧ＣＶＤ、イオンプレーティング、ＰＬＤ、真空蒸着等の乾式法やスプレー、熱分解、ゾルゲル、塗布などの湿式法が用いられる。また、表面のテクスチャ形成には既存のウェットエッチング法、ドライエッチング法、ＬＰＣＶＤやＰＬＤによる自然形成法等から透光性導電膜の材料や成膜法に適した方法が用いられる。   The existing sputtering, plasma CVD, low-pressure CVD, ion plating, PLD, and vacuum deposition are used to form the first light-transmitting conductive film 21 with a low carrier concentration and the second light-transmitting conductive film 22 with a high carrier concentration. A dry method such as spraying, or a wet method such as spraying, thermal decomposition, sol-gel, or coating is used. For the surface texture formation, a method suitable for the material of the translucent conductive film and the film forming method is used from the existing wet etching method, dry etching method, natural forming method by LPCVD or PLD, and the like.

本実施の形態では、ドープ濃度の異なる２種類の導電性酸化物ターゲットを使用してスパッタリングすることで膜中のドナーの量を変え、低キャリア濃度の第１の透光性導電膜２１および高キャリア濃度の第２の透光性導電膜２２のキャリア濃度の調整を添加するドーパントの量を調整することで行う。導電性酸化物とドーパント材料の２つのターゲットを使用し両者の印加電力比を変えることでキャリア濃度の調整をしてもよい。また、ＣＶＤ等を用いる場合はドーパント材料を含むガスの流量を変えることで、膜中のドナーの量を変えキャリア濃度の調整を行う。   In the present embodiment, the amount of donor in the film is changed by sputtering using two types of conductive oxide targets having different dope concentrations, the first light-transmitting conductive film 21 having a low carrier concentration, and a high The carrier concentration of the second light-transmitting conductive film 22 having a carrier concentration is adjusted by adjusting the amount of the dopant to be added. The carrier concentration may be adjusted by using two targets of a conductive oxide and a dopant material and changing the applied power ratio between them. When CVD or the like is used, the carrier concentration is adjusted by changing the flow rate of the gas containing the dopant material to change the amount of donor in the film.

本実施の形態によれば、低キャリア濃度の第１の透光性導電膜２１と高キャリア濃度の第２の透光性導電膜２２の積層膜が太陽電池セルの第１の電極２として機能しつつ、赤外線領域において屈折率差による反射を利用した光学干渉効果により所定の波長付近に急峻な反射特性を得ることができる。一方で、有効波長域では屈折率差が小さくなるため反射が生じないため高い透過率を得ることができる。また、第１の電極２を形成する多層膜において、光電変換層３との界面以外の反射面が平面状に形成されるため、光学干渉の効果が顕著になり、高い赤外線反射効果を得ることができる。   According to the present embodiment, the laminated film of the first light-transmitting conductive film 21 having a low carrier concentration and the second light-transmitting conductive film 22 having a high carrier concentration functions as the first electrode 2 of the solar battery cell. However, steep reflection characteristics in the vicinity of a predetermined wavelength can be obtained by an optical interference effect using reflection due to a difference in refractive index in the infrared region. On the other hand, since the difference in refractive index is small in the effective wavelength region and no reflection occurs, a high transmittance can be obtained. In addition, in the multilayer film forming the first electrode 2, the reflection surface other than the interface with the photoelectric conversion layer 3 is formed in a flat shape, so that the effect of optical interference becomes remarkable and a high infrared reflection effect is obtained. Can do.

実施の形態３．
他の実施の形態として、低キャリア濃度の第１の透光性導電膜２１および高キャリア濃度の第２の透光性導電膜２２のキャリア濃度の調整を成膜中の酸素分圧を変えることで行う。一般的に透光性導電膜として用いられるｎ型導電性酸化物のキャリアはドーパントの添加や酸素欠損により生じた欠陥から生成される。成膜中の酸素分圧を高くすると酸素欠損は減少し、キャリア濃度は低下し、低くすると酸素欠損が増加し、キャリア濃度は上昇する。 Embodiment 3 FIG.
As another embodiment, the oxygen partial pressure during film formation is changed by adjusting the carrier concentration of the first light-transmitting conductive film 21 having a low carrier concentration and the second light-transmitting conductive film 22 having a high carrier concentration. To do. In general, carriers of an n-type conductive oxide used as a light-transmitting conductive film are generated from defects caused by addition of a dopant or oxygen deficiency. When the oxygen partial pressure during film formation is increased, oxygen vacancies are reduced and the carrier concentration is decreased. When it is lowered, oxygen vacancies are increased and the carrier concentration is increased.

本実施の形態では、ＺｎＯ：Ａｌ（３．０ｗｔ％）ターゲットを用いてスパッタリング法により成膜するが、その際、成膜中の酸素分圧を、高めることで、キャリア濃度を低くしている。つまり、第１の透光性導電膜２１ａ，２１ｂ，２１ｃを形成する際、成膜中の雰囲気ガスをアルゴンと酸素の混合ガスとし、全圧を０．５Ｐａ、酸素分圧を０．０１Ｐａとして成膜したＺｎＯ：Ａｌ膜のキャリア濃度は８．８×１０19ｃｍ-3へと低下する。そして続いて、成膜中の雰囲気ガスをアルゴンのみ、全圧を０．５ＰａとしてＺｎＯ：Ａｌ膜を成膜し、キャリア濃度は７．５×１０20ｃｍ-3の第２の透光性導電膜２２ａ，２２ｂを形成する。このようにしてターゲットはそのまま同じものを使用し、酸素分圧のみを交互に変化させることで、極めて容易に多層構造の透光性導電膜を形成することができる。 In this embodiment mode, a film is formed by a sputtering method using a ZnO: Al (3.0 wt%) target. At this time, the carrier concentration is lowered by increasing the oxygen partial pressure during film formation. . That is, when forming the first translucent conductive films 21a, 21b, and 21c, the atmospheric gas during film formation is a mixed gas of argon and oxygen, the total pressure is 0.5 Pa, and the oxygen partial pressure is 0.01 Pa. The carrier concentration of the deposited ZnO: Al film is reduced to 8.8 × 10 19 cm −3 . Then, a ZnO: Al film is formed with argon as the atmospheric gas during film formation, the total pressure is 0.5 Pa, and a second light-transmitting conductive film with a carrier concentration of 7.5 × 10 20 cm −3 . Films 22a and 22b are formed. In this way, the same target is used as it is, and only the oxygen partial pressure is alternately changed, whereby a light-transmitting conductive film having a multilayer structure can be formed very easily.

以上のように、第１および第２の透光性導電膜に同一材料を用いることで、屈折率やバンドギャップが比較的近くなり有効波長域での反射が減少する。また、成膜時の酸素の量を調整することでキャリア濃度が調整でき材料コストが増加しない。   As described above, by using the same material for the first and second translucent conductive films, the refractive index and the band gap are relatively close, and reflection in the effective wavelength region is reduced. Further, the carrier concentration can be adjusted by adjusting the amount of oxygen at the time of film formation, so that the material cost does not increase.

この方法によればスパッタリング法をはじめとしたターゲットを用いた成膜法において１種類のターゲットを用いてキャリア濃度を増減することができるため新たに材料を用いずにキャリア濃度の異なる膜を作製可能である。その他の工程は実施の形態１，２とまったく同一であるため説明を省略する。   According to this method, since the carrier concentration can be increased / decreased by using one type of target in a film forming method using a target such as a sputtering method, a film having a different carrier concentration can be produced without newly using a material. It is. The other steps are exactly the same as those in the first and second embodiments, and thus the description thereof is omitted.

実施の形態４．
次に、実施の形態４として、低キャリア濃度の第１の透光性導電膜２１と高キャリア濃度の第２の透光性導電膜２２に異なる導電性酸化物材料を使用し、低キャリア濃度の第１の透光性導電膜２１に高キャリア濃度の第２の透光性導電膜２２よりもバンドギャップが大きい材料を用いた太陽電池について説明する。 Embodiment 4 FIG.
Next, as Embodiment 4, different conductive oxide materials are used for the first light-transmitting conductive film 21 with a low carrier concentration and the second light-transmitting conductive film 22 with a high carrier concentration. A solar cell using a material having a band gap larger than that of the second light-transmitting conductive film 22 having a high carrier concentration for the first light-transmitting conductive film 21 will be described.

透光性導電膜の短波長域における吸収はバンド間遷移によるものであり、バンドギャップに対応した吸収端を示す。このとき、使用する導電性酸化物材料のバンドギャップに加えて、キャリア濃度が高くなるとキャリア電子が伝導帯底部を占有することにより見かけのバンドギャップが大きくなる現象が知られている(Ｂｕｒｓｔｅｉｎ−Ｍｏｓｓシフト)。このため、同一材料を用いてキャリア濃度の異なる層を積層させると低キャリア濃度の第１の透光性導電膜２１の吸収端が支配的となる。特にＺｎＯ系の材料は安価で材料資源が豊富であり、テクスチャ加工が容易であることから広く利用されているが、ＺｎＯのバンドギャップは３．４ｅＶ程度とＩｎ2Ｏ3やＳｎＯ2と比較して小さく、低キャリア濃度のＺｎＯでは短波長側の吸収端が３５０ｎｍ程度となり、太陽電池の有効波長域で吸収が増加し太陽電池の特性低下につながる場合がある。高キャリア濃度の第２の透光性導電膜２２にＺｎＯ系材料を用いた場合、低キャリア濃度の第１の透光性導電膜２１にはＺｎＯに代えて、Ｉｎ2Ｏ3やＳｎＯ2系材料、もしくはワイドギャップ材料であるＭｇＯやＩｎ2Ｏ3、ＳｎＯ2とＺｎＯとの混晶材料を用いることができる。混晶材料では両者の中間のバンドギャップや屈折率を示すため、低キャリア濃度の第１の透光性導電膜２１と高キャリア濃度の第２の透光性導電膜２２がバンドギャップや屈折率の点で比較的近い特性の膜を得ることができる。また、屈折率は同材料でキャリア濃度のみを低減させた場合は図６に示したように赤外線領域で大きく上昇することに加え、欠陥が低減するため可視光域においてもわずかに上昇する。このため、低キャリア濃度の第１の透光性導電膜２１の材料に、ＺｎＯやＩｎ2Ｏ3、ＳｎＯ2（ｎ＠６００ｎｍ＝１．９〜２．１）と比較して屈折率の低い酸化マグネシウム（ｎ＠６００ｎｍ＝１．７）を用いることで低キャリア濃度の第１の透光性導電膜２１と高キャリア濃度の第２の透光性導電膜２２の可視光領域での屈折率の差をより小さくすることが可能である。また、実施の形態２または３と複数の方法を組み合わせて透光性導電膜のキャリア濃度を調整してもよい。 Absorption in the short wavelength region of the translucent conductive film is due to interband transition and shows an absorption edge corresponding to the band gap. At this time, in addition to the band gap of the conductive oxide material to be used, it is known that when the carrier concentration increases, the carrier band occupies the bottom of the conduction band and the apparent band gap increases (Burstein-Moss). shift). For this reason, when layers having different carrier concentrations are stacked using the same material, the absorption edge of the first light-transmitting conductive film 21 having a low carrier concentration becomes dominant. In particular, ZnO-based materials are widely used because they are inexpensive and have abundant material resources, and are easy to texture. However, the band gap of ZnO is about 3.4 eV, which is compared to In 2 O 3 and SnO 2. In the case of ZnO having a small and low carrier concentration, the absorption edge on the short wavelength side is about 350 nm, and absorption may increase in the effective wavelength region of the solar cell, leading to deterioration of the characteristics of the solar cell. When a ZnO-based material is used for the second light-transmitting conductive film 22 having a high carrier concentration, the first light-transmitting conductive film 21 having a low carrier concentration is replaced with Zn 2 O 3 or SnO 2 -based material. A material, or a mixed crystal material of MgO, In 2 O 3 , SnO 2 and ZnO, which is a wide gap material, can be used. Since the mixed crystal material shows a band gap and refractive index intermediate between the two, the first transparent conductive film 21 having a low carrier concentration and the second transparent conductive film 22 having a high carrier concentration have a band gap and a refractive index. Thus, a film having relatively close characteristics can be obtained. In addition, when only the carrier concentration is reduced with the same material, the refractive index increases significantly in the infrared region as shown in FIG. 6 and also slightly increases in the visible light region because defects are reduced. Therefore, the material of the first light-transmitting conductive film 21 having a low carrier concentration has a low refractive index as compared with ZnO, In 2 O 3 , and SnO 2 (n @ 600 nm = 1.9 to 2.1). By using magnesium oxide (n @ 600 nm = 1.7), the refractive index in the visible light region of the first light-transmitting conductive film 21 having a low carrier concentration and the second light-transmitting conductive film 22 having a high carrier concentration. It is possible to further reduce the difference. Further, the carrier concentration of the light-transmitting conductive film may be adjusted by combining Embodiment 2 or 3 and a plurality of methods.

図９にＺｎＯとＭｇＯの混晶材料（Ｚｎ1-xＭｇxＯ）の屈折率の一例を示す。曲線ａで示す例ではＭｇＯの組成比をｘを２０ａｔ．％とし、Ａｌを１．０ｗｔ％ドープしている。比較のため、曲線ｂで示す例では、３．０ｗｔ％ＡｌをドープしたＺｎＯの屈折率を合わせて示す。Ｚｎ0.8Ｍｇ0.2Ｏ：Ａｌ（０．５ｗｔ％）のキャリア濃度は１．９×１０20ｃｍ-3であった。ＺｎＭｇＯ膜では、ＭｇＯ組成比を増加させると酸素欠損の減少によりキャリア濃度は低下するが、バンドギャップが増加するため短波長側の吸収端は短波長側へとシフトする。また、ＺｎＭｇＯ膜の屈折率はＺｎＯ：Ａｌ（３．０ｗｔ％）と比較してキャリア濃度の低減により赤外線領域で大きく上昇する一方、可視光領域付近では欠陥が低減することによる屈折率の上昇とＭｇＯとの混晶による屈折率の低下が合わせて生じるためＺｎＯ：Ａｌ（３．０ｗｔ％）と非常に近い値を示す。これにより同一材料でキャリア濃度のみを変化させた場合より有効波長域での屈折率差が小さくなり反射ロスをより抑制することができる。ガラス基板上に図９に示すＺｎＭｇＯを低キャリア濃度の第１の透光性導電膜、ＺｎＯ：Ａｌ（３．０ｗｔ％）を高キャリア濃度の第２の透光性導電膜として用いて３層および５層積層した多層膜の反射率の波長依存性の計算結果を図１０に示す。曲線ａおよびｂではそれぞれ３層膜および５層膜について示す。膜厚は低キャリア濃度の第１の透光性導電膜を１６８ｎｍ、高キャリア濃度の第２の透光性導電膜を２５２ｎｍと設定した。前記の理由により、ＺｎＯのキャリア濃度を変えた多層膜と比較し、有効波長域（特にバンドギャップ付近の短波長領域）で反射率が低下していることがわかる。 FIG. 9 shows an example of the refractive index of a mixed crystal material (Zn 1-x Mg x O) of ZnO and MgO. In the example shown by the curve a, the MgO composition ratio x is 20 at. %, And Al is doped by 1.0 wt%. For comparison, in the example shown by the curve b, the refractive index of ZnO doped with 3.0 wt% Al is also shown. The carrier concentration of Zn 0.8 Mg 0.2 O: Al (0.5 wt%) was 1.9 × 10 20 cm −3 . In the ZnMgO film, when the MgO composition ratio is increased, the carrier concentration is lowered due to the reduction of oxygen vacancies, but the band gap is increased, so that the absorption edge on the short wavelength side is shifted to the short wavelength side. In addition, the refractive index of the ZnMgO film is greatly increased in the infrared region by reducing the carrier concentration compared to ZnO: Al (3.0 wt%), while the refractive index is increased by reducing defects in the vicinity of the visible light region. Since a decrease in refractive index due to a mixed crystal with MgO occurs together, the value is very close to that of ZnO: Al (3.0 wt%). As a result, the refractive index difference in the effective wavelength region becomes smaller than when only the carrier concentration is changed using the same material, and reflection loss can be further suppressed. Three layers are formed on a glass substrate using ZnMgO as a first light-transmitting conductive film with a low carrier concentration and ZnO: Al (3.0 wt%) as a second light-transmitting conductive film with a high carrier concentration shown in FIG. FIG. 10 shows a calculation result of the wavelength dependence of the reflectance of the multilayer film in which five layers are stacked. Curves a and b show a three-layer film and a five-layer film, respectively. The film thickness was set to 168 nm for the first light-transmitting conductive film having a low carrier concentration and 252 nm for the second light-transmitting conductive film having a high carrier concentration. For the above reason, it can be seen that the reflectance is reduced in the effective wavelength region (particularly, the short wavelength region near the band gap) as compared with the multilayer film in which the ZnO carrier concentration is changed.

本実施の形態によれば赤外線反射効果は実施の形態１から３と同様に維持したまま有効波長域の透過率を高めることができる。その他の工程は実施の形態１から３と同一であるため説明を省略する。   According to the present embodiment, the transmittance in the effective wavelength region can be increased while the infrared reflection effect is maintained in the same manner as in the first to third embodiments. The other steps are the same as those in the first to third embodiments, and thus description thereof is omitted.

実施の形態５．
上記の実施の形態１から４ではスーパーストレート型の薄膜太陽電池について述べたが、サブストレート型の薄膜太陽電池においても同様に適用できる。本実施の形態では、図１１に示すように、透光性基板１の上に裏面電極である第２の電極４、光電変換層３を積層し、その上に低キャリア濃度の第１の透光性導電膜２１と高キャリア濃度の第２の透光性導電膜２２を交互に積層させた受光面電極としての第１の電極２が形成される。 Embodiment 5 FIG.
Although the super straight type thin film solar cell has been described in the first to fourth embodiments, the present invention can be similarly applied to a substrate type thin film solar cell. In the present embodiment, as shown in FIG. 11, the second electrode 4 and the photoelectric conversion layer 3 which are back electrodes are stacked on the light-transmitting substrate 1, and the first transparent substrate with a low carrier concentration is formed thereon. The first electrode 2 is formed as a light-receiving surface electrode in which the photoconductive film 21 and the second translucent conductive film 22 having a high carrier concentration are alternately stacked.

次に、本実施の形態の太陽電池の製造方法について説明する。図１２はその製造工程を示すフローチャート図である。本実施の形態が、実施の形態１と異なるのは、まず、透光性基板１にテクスチャエッチングを行い、このテクスチャ構造を維持するように第２の電極４および第１の電極２を形成するようにした点である。第１の電極２を構成する４層の多層膜を順次形成する点については、高キャリア濃度を有する第２の透光性導電膜２２を光電変換層３側に配する点で同じである。これは第２の透光性導電膜２２と光電変換層３の赤外線領域における屈折率差を大きくして界面における反射を得るためである。   Next, the manufacturing method of the solar cell of this Embodiment is demonstrated. FIG. 12 is a flowchart showing the manufacturing process. The present embodiment is different from the first embodiment in that first, texture etching is performed on the translucent substrate 1, and the second electrode 4 and the first electrode 2 are formed so as to maintain this texture structure. This is the point. The point that the four-layered multilayer film constituting the first electrode 2 is sequentially formed is the same in that the second translucent conductive film 22 having a high carrier concentration is disposed on the photoelectric conversion layer 3 side. This is to increase the refractive index difference in the infrared region between the second translucent conductive film 22 and the photoelectric conversion layer 3 to obtain reflection at the interface.

つまり、ガラス基板からなる透光性基板１表面に、テクスチャを形成し、第２の電極４である裏面電極を形成し、少なくとも１組のｐｉｎ構造を有する光電変換層３を形成した後、第２の透光性導電膜２２ｂ、第１の透光性導電膜２１ｂ、第２の透光性導電膜２２ａ、第１の透光性導電膜２１ａを順に形成する（Ｓ１２〜Ｓ１５）。このように、最後に第１の電極２である受光面電極を積層する。   That is, after the texture is formed on the surface of the translucent substrate 1 made of a glass substrate, the back electrode as the second electrode 4 is formed, and the photoelectric conversion layer 3 having at least one pair of pin structures is formed, Two light-transmitting conductive films 22b, a first light-transmitting conductive film 21b, a second light-transmitting conductive film 22a, and a first light-transmitting conductive film 21a are sequentially formed (S12 to S15). Thus, the light-receiving surface electrode which is the first electrode 2 is finally laminated.

製造に際しては、まず、透光性基板１として、ガラス基板を用意する。そして、このガラス基板に研磨剤としてアルミナ粉末を混合した水を吹き付けるウオータブラスト法により粗面化し、さらにフッ酸水溶液を用いたエッチング処理により凹凸部を有する透光性基板１を得る(ステップＳ１１１)。   In manufacturing, first, a glass substrate is prepared as the translucent substrate 1. Then, the glass substrate is roughened by a water blast method in which water in which alumina powder is mixed as an abrasive is sprayed, and a light-transmitting substrate 1 having uneven portions is obtained by etching using an aqueous hydrofluoric acid solution (step S111). .

そして、この透光性基板１上に、第２の電極４としての膜厚５００ｎｍの銀をスパッタリング法で堆積した後、不純物としてＡｌ原子を２×１０21ｃｍ−3程度ドープしたＺｎＯ膜をスパッタリング法により膜厚１００ｎｍ成膜し、拡散防止膜とした（ステップＳ１１２）。このとき、拡散防止膜で被覆された第２の電極４の表面には凹凸部が形成されている。 Then, after depositing 500 nm of silver as the second electrode 4 on the translucent substrate 1 by a sputtering method, a ZnO film doped with about 2 × 10 21 cm −3 of Al atoms as an impurity is sputtered. A film having a thickness of 100 nm was formed by the method to obtain a diffusion prevention film (step S112). At this time, an uneven portion is formed on the surface of the second electrode 4 covered with the diffusion preventing film.

そして、この第２の電極４の形成された透光性基板１上に、光電変換層３として、膜厚２０ｎｍのｐ型微結晶シリコン層、膜厚２μｍのｉ型（真性の）微結晶シリコン層、膜厚３０ｎｍのｎ型微結晶シリコン層をプラズマＣＶＤ法により積層した（ステップＳ１１３）。次いで４層の透光性導電膜からなる第１の電極２を形成する（ステップＳ１１４）。第２の透光性導電膜２２ｂの形成ステップ（Ｓ１２）、第１の透光性導電膜２１ｂの形成ステップ（Ｓ１３）、第２の透光性導電膜２２ａの形成ステップ（Ｓ１４）、第１の透光性導電膜２１ａの形成ステップ（Ｓ１５）を順次行う。このとき、最上層の第１の透光性導電膜２１ａの表面には凹凸部が形成されている。成膜に際しては、例えば成膜チャンバ内にＡｒとＯ2とＨ2を導入し、Ｉｎ2Ｏ3ターゲットをスパッタリングすることにより、膜厚２００ｎｍのＨドープＩｎ2Ｏ3を堆積した。このとき各層で酸素分圧を変化させることで酸素濃度を調整した。このようにして、図１１に示したような太陽電池が形成される。 Then, on the translucent substrate 1 on which the second electrode 4 is formed, a p-type microcrystalline silicon layer having a thickness of 20 nm and an i-type (intrinsic) microcrystalline silicon having a thickness of 2 μm are formed as the photoelectric conversion layer 3. An n-type microcrystalline silicon layer having a thickness of 30 nm was stacked by the plasma CVD method (step S113). Next, the first electrode 2 made of a four-layer translucent conductive film is formed (step S114). Step of forming second light-transmitting conductive film 22b (S12), step of forming first light-transmitting conductive film 21b (S13), step of forming second light-transmitting conductive film 22a (S14), first The step (S15) of forming the transparent conductive film 21a is sequentially performed. At this time, an uneven portion is formed on the surface of the uppermost first translucent conductive film 21a. In film formation, for example, Ar, O 2, and H 2 were introduced into a film formation chamber, and an In 2 O 3 target was sputtered to deposit H-doped In 2 O 3 having a thickness of 200 nm. At this time, the oxygen concentration was adjusted by changing the oxygen partial pressure in each layer. Thus, the solar cell as shown in FIG. 11 is formed.

サブストレート型太陽電池の場合、光閉じ込めを目的としたテクスチャ構造が透光性基板１もしくは裏面電極である第２の電極４に形成されるのが一般的であり、その上に積層される層も凹凸形状となる。このため、第１の電極２でテクスチャを形成する必要はなく、全ての層において光学膜厚を一定とすることが好ましい。低キャリア濃度の第１の透光性導電膜２１と高キャリア濃度の第２の透光性導電膜２２の界面が凹凸形状となるため界面の反射や膜厚の調整による光学干渉の効果が平面上に形成される実施の形態１から４と比較すると弱くなるが、同様に可視光線領域の高い透過率を維持したまま赤外線反射効果を得ることができる。   In the case of a substrate type solar cell, a texture structure aiming at light confinement is generally formed on the translucent substrate 1 or the second electrode 4 which is a back electrode, and a layer laminated thereon. Is also uneven. For this reason, it is not necessary to form a texture with the 1st electrode 2, and it is preferable to make optical film thickness constant in all the layers. Since the interface between the first light-transmitting conductive film 21 having a low carrier concentration and the second light-transmitting conductive film 22 having a high carrier concentration has an uneven shape, the reflection of the interface and the effect of optical interference by adjusting the film thickness are flat. Although it becomes weaker than the first to fourth embodiments formed above, an infrared reflection effect can be obtained while maintaining a high transmittance in the visible light region.

実施の形態６．
上記の実施の形態１から５では受光面電極である第１の電極を構成する多層膜の低キャリア濃度層とテクスチャ形成層を同一組成の透光性導電膜で構成したが、図４に示した実施の形態２の太陽電池においては、テクスチャを形成する面のみをこの繰り返し多層構造の透光性導電膜とは異なる組成の透光性膜で構成してもよい。例えば図１３に示すように、テクスチャ５Ｔを有する透光性膜５を介在させるようにしてもよい。 Embodiment 6 FIG.
In the above first to fifth embodiments, the low carrier concentration layer and the texture forming layer of the multilayer film constituting the first electrode which is the light receiving surface electrode are formed of the light transmitting conductive film having the same composition. In the solar cell of the second embodiment, only the surface on which the texture is formed may be composed of a light-transmitting film having a composition different from that of the light-transmitting conductive film having a multilayer structure. For example, as shown in FIG. 13, a translucent film 5 having a texture 5T may be interposed.

透光性基板１上に、同様にして５層の透光性導電膜２１ａ，２２ａ，２１ｂ，２２ｂ，２１ｃを形成した後、透光性膜５を形成し、テクスチャ５Ｔを形成する。   Similarly, after forming five layers of light-transmitting conductive films 21a, 22a, 21b, 22b, and 21c on the light-transmitting substrate 1, the light-transmitting film 5 is formed, and the texture 5T is formed.

つまり図５に示したフローチャートにおいてステップＳ１５までを実施して形成した５層構造の透光性導電膜上に、透光性膜５として、例えばＡｌを０．５ｗｔ％ドープしたＺｎＯとＭｇＯとの同時スパッタリング法により膜厚１μｍのＺｎＭｇＯ膜を成膜した。ＺｎＭｇＯのキャリア濃度は１×１０20ｃｍ-3、Ｚｎに対するＭｇの組成比は１５ａｔ．％であった。このとき、透光性膜５は主として六方晶を構成している。なお、この透光性膜５としてはドーパントを含まないＺｎＭｇＯ膜など、キャリア濃度の極めて低い膜であってもよい。 That is, for example, ZnO and MgO doped with 0.5 wt% of Al as the light-transmitting film 5 are formed on the light-transmitting conductive film having a five-layer structure formed by performing up to Step S15 in the flowchart shown in FIG. A ZnMgO film having a thickness of 1 μm was formed by the co-sputtering method. The carrier concentration of ZnMgO is 1 × 10 20 cm −3 , and the composition ratio of Mg to Zn is 15 at. %Met. At this time, the translucent film 5 mainly constitutes a hexagonal crystal. The translucent film 5 may be a film having a very low carrier concentration, such as a ZnMgO film containing no dopant.

次に、０．５％に希釈された塩酸を用いて、透光性膜５としてのＺｎＭｇＯのエッチング処理を６０秒間実施する（テクスチャの形成Ｓ１６）ことにより、受光面と反対側の面に凹凸部（テクスチャ５Ｔ）を有するテクスチャ構造を有する透光性膜５を形成した。   Next, the etching treatment of ZnMgO as the translucent film 5 is performed for 60 seconds using hydrochloric acid diluted to 0.5% (formation of texture S16), so that the surface opposite to the light receiving surface is uneven. The translucent film | membrane 5 which has a texture structure which has a part (texture 5T) was formed.

つまり図５に示したフローチャートのステップＳ１５とＳ１６との間に透光性膜５を形成する工程を実行するものであり、後のステップについては、図５に示したフローチャートにしたがって実施すればよい。本実施の形態においても第２の電極４の裏面Ｂ側にもテクスチャ４Ｔが形成されている。   That is, the process of forming the translucent film 5 is performed between steps S15 and S16 of the flowchart shown in FIG. 5, and the subsequent steps may be performed according to the flowchart shown in FIG. . Also in the present embodiment, the texture 4T is formed on the back surface B side of the second electrode 4.

本実施の形態では、図１３に示したように、膜厚を厚くする必要があるテクスチャ形成層に透過率の高いＺｎＭｇＯを用いるため、ＺｎＯのみを用いる場合と比較して受光面電極全体としての透過率が向上する。また、本実施の形態のように、テクスチャ層と多層膜を別材料とする場合、例えば、多層膜をＩｎＯ系の材料、テクスチャ形成層をＺｎＯ系のＺｎＭｇＯとして形成することで、ＩｎＯ系材料の高い光透過性および導電性と、ＺｎＯ系材料を用いたテクスチャ構造による光散乱性を両立することも可能である。   In this embodiment, as shown in FIG. 13, since ZnMgO having a high transmittance is used for the texture forming layer that needs to have a large film thickness, the entire light-receiving surface electrode is compared with the case where only ZnO is used. The transmittance is improved. Further, when the texture layer and the multilayer film are made of different materials as in the present embodiment, for example, by forming the multilayer film as an InO-based material and the texture forming layer as a ZnO-based ZnMgO, It is also possible to achieve both high light transmittance and conductivity and light scattering by a texture structure using a ZnO-based material.

実施例１．
まず、透光性基板１として、厚さ０．７ｍｍ、１００ｍｍ×１００ｍｍのコーニング♯７９５９からなるガラス基板を用意する。この透光性基板１上に、低キャリア濃度の第１の透光性導電膜２１にＺｎＯ：Ａｌ（０．５ｗｔ％）、高キャリア濃度の第２の透光性導電膜２２にＺｎＯ：Ａｌ（３．０ｗｔ％）を用いてこの順に膜厚を１７２ｎｍ／２５２ｎｍ／６００ｎｍとして成膜し、受光面電極である第１の電極２を形成した。第１の電極２上に、第１の光電変換層として非晶質Ｓｉ系薄膜からなるｐｉｎ層を、第２の光電変換層として微結晶Ｓｉ系薄膜からなるｐｉｎ層を積層し、光電変換層３を形成した。ｉ層の膜厚はそれぞれ３００ｎｍ、２０００ｎｍとした。光電変換層３上に、裏面電極である第２の電極４としてＺｎＯとＡｇを膜厚がそれぞれ９０ｎｍ／３００ｎｍとなるように形成し、太陽電池セルを作製した。ＺｎＯはＡｇが光電変換層３中へ拡散することを防止するために挿入している。 Example 1.
First, as the translucent substrate 1, a glass substrate made of Corning # 7959 having a thickness of 0.7 mm and 100 mm × 100 mm is prepared. On this translucent substrate 1, ZnO: Al (0.5 wt%) is applied to the first translucent conductive film 21 having a low carrier concentration, and ZnO: Al is applied to the second translucent conductive film 22 having a high carrier concentration. (3.0 wt%) was used in this order to form a film with a film thickness of 172 nm / 252 nm / 600 nm to form a first electrode 2 that is a light-receiving surface electrode. On the first electrode 2, a pin layer made of an amorphous Si-based thin film is laminated as a first photoelectric conversion layer, and a pin layer made of a microcrystalline Si-based thin film is laminated as a second photoelectric conversion layer, and a photoelectric conversion layer 3 was formed. The thickness of the i layer was 300 nm and 2000 nm, respectively. On the photoelectric conversion layer 3, ZnO and Ag were formed as the 2nd electrode 4 which is a back surface electrode so that film thickness might be 90 nm / 300 nm, respectively, and the photovoltaic cell was produced. ZnO is inserted in order to prevent Ag from diffusing into the photoelectric conversion layer 3.

実施例２．
実施例１と同様、透光性基板１としてのガラス基板上に、低キャリア濃度の第１の透光性導電膜２１にＺｎＯ：Ａｌ（０．５ｗｔ％）、高キャリア濃度の第２の透光性導電膜２２にＺｎＯ：Ａｌ（３．０ｗｔ％）を用いて交互に膜厚を１７２ｎｍ／２５２ｎｍ／１７２ｎｍ／２５２ｎｍ／６００ｎｍとして成膜して第１の電極２を形成し、それ以外は実施例１と同様にして太陽電池セルを作製した。 Example 2
Similar to Example 1, on the glass substrate as the light-transmitting substrate 1, the first light-transmitting conductive film 21 having a low carrier concentration was coated with ZnO: Al (0.5 wt%) and the second light-transmitting layer having a high carrier concentration. The first electrode 2 is formed by forming ZnO: Al (3.0 wt%) on the photoconductive film 22 alternately at a film thickness of 172 nm / 252 nm / 172 nm / 252 nm / 600 nm. A solar battery cell was produced in the same manner as in Example 1.

実施例３．
実施例１と同様、透光性基板１としてのガラス基板上に、低キャリア濃度の第１の透光性導電膜２１にＺｎ０・８Ｍｇ０．２Ｏ：Ａｌ（１．０ｗｔ％）、高キャリア濃度の第２の透光性導電膜２２にＺｎＯ：Ａｌ（３．０ｗｔ％）を用いてこの順に膜厚を１６８ｎｍ／２５２ｎｍ／６００ｎｍとして成膜して第１の電極２を形成し、それ以外は実施例１と同様にして太陽電池セルを作製した。 Example 3
Similar to Example 1, on the glass substrate as the light-transmitting substrate 1, the first light-transmitting conductive film 21 with a low carrier concentration was coated with Zn 0 · 8 Mg 0.2 O: Al (1.0 wt%), The first electrode 2 is formed by using ZnO: Al (3.0 wt%) as the second light-transmitting conductive film 22 having a high carrier concentration and forming a film with a thickness of 168 nm / 252 nm / 600 nm in this order. Other than that was carried out similarly to Example 1, and produced the photovoltaic cell.

比較例１．
透光性基板１としてのガラス基板上に、ＺｎＯ：Ａｌ（０．５ｗｔ％）を膜厚１１００ｎｍとして成膜して第１の電極２を形成し、それ以外は実施例１と同様にして太陽電池セルを作製した。 Comparative Example 1
A first electrode 2 is formed by forming a film of ZnO: Al (0.5 wt%) with a film thickness of 1100 nm on a glass substrate as the light-transmitting substrate 1, and otherwise the same as in Example 1 A battery cell was produced.

比較例２．
透光性基板１としてのガラス基板上に、ＺｎＯ：Ａｌ（３．０ｗｔ％）を膜厚９００ｎｍとして成膜して第１の電極２を形成し、それ以外は実施例１と同様にして太陽電池セルを作製した。 Comparative Example 2
A first electrode 2 is formed on a glass substrate as the light-transmitting substrate 1 by forming a film of ZnO: Al (3.0 wt%) with a film thickness of 900 nm. A battery cell was produced.

本実施例の効果について次の項目により評価した。
テクスチャ形成前の透光性基板１と第１の電極２において分光光度計を用いて以下の各波長域の透過率および反射率を求めた。実施例１から３では、透過率および反射率測定後にテクスチャ形成を行い、図４に示した実施の形態２の太陽電池と同様の構成をとるように形成するものとし、比較例１および２でも同様に透過率および反射率測定後、テクスチャ形成を行い、太陽電池を形成した。
平均近紫外線透過率：波長３００〜４００ｎｍにおける平均透過率
平均可視光線〜近赤外線透過率：波長４００〜１１００ｎｍにおける平均透過率
平均赤外線反射率：波長１１００〜１５００ｎｍにおける平均反射率
また、四探針法によって受光面電極である第１の電極２のシート抵抗を求めた。その結果を図１４に示す。 The effects of this example were evaluated by the following items.
Using the spectrophotometer in the translucent substrate 1 and the 1st electrode 2 before texture formation, the transmittance | permeability and reflectance of each following wavelength range were calculated | required. In Examples 1 to 3, the texture is formed after measuring the transmittance and the reflectance, and the solar cell of the second embodiment shown in FIG. 4 is formed to have the same configuration. Similarly, after measuring transmittance and reflectance, texture formation was performed to form a solar cell.
Average near ultraviolet transmittance: Average transmittance at a wavelength of 300 to 400 nm Average visible light to Near infrared transmittance: Average transmittance at a wavelength of 400 to 1100 nm Average infrared reflectance: Average reflectance at a wavelength of 1100 to 1500 nm Thus, the sheet resistance of the first electrode 2 which is the light receiving surface electrode was obtained. The result is shown in FIG.

図１４に示す測定結果より、実施例１から３の第１の電極では有効波長域での透過率とシート抵抗を維持しながら高い赤外線反射率を有していることがわかる。一方で、透光性導電膜を単層で成膜した比較例では赤外線反射率が６％程度と赤外線遮蔽効果がほとんど得られないことがわかる。特に、実施例１および３では低キャリアの透光性導電膜を単層で成膜した比較例１と同等かそれ以上の可視光線透過率を有している。実施例３では、低キャリア透光性導電膜にＺｎＭｇＯを使用しているため近紫外線領域においても高い透過率が得られている。実施例２の５層構造では４０％以上の特に高い赤外線反射率が得られる。一方で、総膜厚が厚くなるため、わずかに透過率が低下するがシート抵抗も他よりも低いため、膜厚やキャリア濃度を最適化することで透過率を高めることができると予想される。   From the measurement results shown in FIG. 14, it can be seen that the first electrodes of Examples 1 to 3 have high infrared reflectance while maintaining the transmittance and sheet resistance in the effective wavelength region. On the other hand, in the comparative example in which the translucent conductive film is formed as a single layer, it is understood that the infrared ray shielding effect is hardly obtained with an infrared reflectance of about 6%. In particular, Examples 1 and 3 have a visible light transmittance equal to or higher than that of Comparative Example 1 in which a low carrier translucent conductive film is formed as a single layer. In Example 3, since ZnMgO is used for the low carrier translucent conductive film, high transmittance is obtained even in the near ultraviolet region. In the five-layer structure of Example 2, a particularly high infrared reflectance of 40% or more is obtained. On the other hand, since the total film thickness becomes thick, the transmittance slightly decreases, but the sheet resistance is also lower than the others, so it is expected that the transmittance can be increased by optimizing the film thickness and carrier concentration. .

作製した太陽電池セルはソーラーシミュレータにて１００ｍＷ／ｃｍ2の照度で３０分放置した後の表面温度を測定した。また、同様に３０分間光照射後の変換効率を測定した。また、表面温度２５度における太陽電池セルの変換効率を１００％としたときの変換効率維持率を図１５に示す。 The produced solar battery cell was measured for surface temperature after being left for 30 minutes at an illuminance of 100 mW / cm 2 with a solar simulator. Similarly, the conversion efficiency after 30 minutes of light irradiation was measured. Moreover, the conversion efficiency maintenance factor when the conversion efficiency of the photovoltaic cell in the surface temperature of 25 degree | times is set to 100% is shown in FIG.

図１５に示す測定結果より、実施例１から３では赤外線反射による太陽電池セルの温度上昇を抑制する効果があり、３０分間の光照射後も高い変換効率維持率を示すことがわかる。一方で、比較例では赤外線反射効果が得られないため、光照射後の太陽電池セルの温度が大幅に上昇した。このため変換効率維持率が低くなり、光照射後の変換効率は実施例よりも低い値となった。   From the measurement results shown in FIG. 15, it can be seen that Examples 1 to 3 have the effect of suppressing the temperature rise of the solar battery cell due to infrared reflection, and show a high conversion efficiency maintenance rate even after 30 minutes of light irradiation. On the other hand, since the infrared reflection effect cannot be obtained in the comparative example, the temperature of the solar battery cell after the light irradiation has increased significantly. For this reason, the conversion efficiency maintenance rate became low, and the conversion efficiency after light irradiation became a value lower than an Example.

１ 透光性基板、２ 第１の電極、２Ｔ テクスチャ、３ 光電変換層、４ 第２の電極、４Ｐ 透光性導電膜、４Ｔ テクスチャ、５ 透光性膜、５Ｔ テクスチャ、Ｒ1，Ｒ2 リード、２１，２１ａ，２１ｂ，２１ｃ 第１の透光性導電膜、２２，２２ａ，２２ｂ 第２の透光性導電膜。   1 translucent substrate, 2 first electrode, 2T texture, 3 photoelectric conversion layer, 4 second electrode, 4P translucent conductive film, 4T texture, 5 translucent film, 5T texture, R1, R2 lead, 21, 21a, 21b, 21c 1st translucent conductive film, 22, 22a, 22b 2nd translucent conductive film.

Claims (11)

第１の電極と、第２の電極とによって半導体層からなる光電変換層を挟んだ太陽電池であって、
前記第１および第２の電極のうち、受光面側に配される電極が、
第１の透光性導電膜と、前記第１の透光性導電膜よりも高キャリア濃度を有する第２の透光性導電膜とが交互に積層された３層以上の多層膜で構成されたことを特徴とする太陽電池。 A solar cell in which a photoelectric conversion layer composed of a semiconductor layer is sandwiched between a first electrode and a second electrode,
Of the first and second electrodes, the electrode disposed on the light receiving surface side is
It is composed of a multilayer film of three or more layers in which a first light-transmitting conductive film and a second light-transmitting conductive film having a higher carrier concentration than the first light-transmitting conductive film are alternately stacked. A solar cell characterized by that. 前記第１および第２の透光性導電膜のうち、キャリア濃度の低い、前記第１の透光性導電膜が、前記光電変換層に当接する側に配されたことを特徴とする請求項１に記載の太陽電池。   The first light-transmitting conductive film having a low carrier concentration among the first and second light-transmitting conductive films is disposed on a side in contact with the photoelectric conversion layer. 1. The solar cell according to 1. 前記第１および第２の透光性導電膜は、光学膜厚が等しいことを特徴とする請求項１または２に記載の太陽電池。   The solar cell according to claim 1, wherein the first and second translucent conductive films have the same optical film thickness. 前記第１の電極を構成する透光性導電膜のうち、前記光電変換層に当接する第１の透光性導電膜は前記光電変換層との界面にテクスチャ構造を形成してなることを特徴とする請求項２に記載の太陽電池。   Among the translucent conductive films constituting the first electrode, the first translucent conductive film in contact with the photoelectric conversion layer has a texture structure formed at the interface with the photoelectric conversion layer. The solar cell according to claim 2. 前記第１の電極を構成する透光性導電膜のうち、前記光電変換層に当接する第１の透光性導電膜以外は光学膜厚が等しいことを特徴とする請求項４に記載の太陽電池。   5. The sun according to claim 4, wherein among the translucent conductive films constituting the first electrode, the optical film thickness is the same except for the first translucent conductive film in contact with the photoelectric conversion layer. battery. 前記第１の透光性導電膜のキャリア濃度が０．２から３．５×１０20ｃｍ-3であり、前記第２の透光性導電膜のキャリア濃度が５．０から１５．０×１０20ｃｍ-3であることを特徴とする請求項１から５のいずれか１項に記載の太陽電池。 The carrier concentration of the first light-transmitting conductive film is 0.2 to 3.5 × 10 20 cm −3 , and the carrier concentration of the second light-transmitting conductive film is 5.0 to 15.0 ×. The solar cell according to any one of claims 1 to 5, wherein the solar cell is 10 20 cm -3 . 前記第１の透光性導電膜と前記第２の透光性導電膜は同一材料で構成され、
前記第１および第２の透光性導電膜は、添加されるドーパントの量が異なることを特徴とする請求項１から６のいずれか１項に記載の太陽電池。 The first translucent conductive film and the second translucent conductive film are made of the same material,
The solar cell according to any one of claims 1 to 6, wherein the first and second light-transmitting conductive films have different amounts of added dopant. 前記第１の透光性導電膜と前記第２の透光性導電膜は同一材料で構成され、
前記第１および第２の透光性導電膜は、膜中の酸素欠損の量が異なることを特徴とする請求項１から６のいずれか１項に記載の太陽電池。 The first translucent conductive film and the second translucent conductive film are made of the same material,
The solar cell according to claim 1, wherein the first and second light-transmitting conductive films have different amounts of oxygen vacancies in the films. 前記第１の透光性導電膜は、前記第２の透光性導電膜の構成材料と、前記構成材料よりもバンドギャップが大きい材料との混晶材料であることを特徴とする請求項１から６のいずれか１項に記載の太陽電池。   The first light-transmitting conductive film is a mixed crystal material of a constituent material of the second light-transmitting conductive film and a material having a band gap larger than that of the constituent material. The solar cell according to any one of 1 to 6. 前記第１の電極、前記光電変換層および前記第２の電極は、透光性基板上に順次積層され、前記第１の電極が受光面側に配されることを特徴とする請求項１から９のいずれか１項に記載の太陽電池。   The first electrode, the photoelectric conversion layer, and the second electrode are sequentially stacked on a light-transmitting substrate, and the first electrode is disposed on a light receiving surface side. 10. The solar cell according to any one of 9 above. 請求項１から１０のいずれか１項に記載の太陽電池と、
前記太陽電池の少なくとも一部を覆う保護部材と、
前記第１および第２の電極にそれぞれ接続された第１および第２のリードとを備えたことを特徴とする太陽電池モジュール。 The solar cell according to any one of claims 1 to 10,
A protective member covering at least a part of the solar cell;
A solar cell module comprising first and second leads connected to the first and second electrodes, respectively.
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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110676353A (en) * 2019-10-28 2020-01-10 成都晔凡科技有限公司 Film coating device and method for manufacturing heterojunction solar cell and laminated assembly
CN110739353A (en) * 2018-07-02 2020-01-31 北京汉能光伏投资有限公司 Film layer structure, solar module and preparation method of solar module

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN110739353A (en) * 2018-07-02 2020-01-31 北京汉能光伏投资有限公司 Film layer structure, solar module and preparation method of solar module
CN110676353A (en) * 2019-10-28 2020-01-10 成都晔凡科技有限公司 Film coating device and method for manufacturing heterojunction solar cell and laminated assembly
CN110676353B (en) * 2019-10-28 2024-04-26 通威太阳能(金堂)有限公司 Coating device and method for manufacturing heterojunction solar cell and laminated tile assembly

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