JP2011222752A - Solar battery module and solar battery cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solar battery module in which a deterioration in moisture resistance is restrained and a light utilization factor (power generation efficiency) is improved.SOLUTION: A solar battery module comprises a solar battery cell having a light trapping film and an anti-reflection film. The light trapping film is formed by microscopic convex or concave pyramids or cones which are tightly spread in quantity, has a refraction factor of 1.55 to 2.40, constituted by organic or non organic hybrid composition made of a titanium tetra alkoxide, has a standardized absorbance a which is indicated by a following formula, of 0.1 or less with respect to a frequency of 400 to 1200 nm; (formula 1) a[-/μm]=-log10(T)/L (T is a transmittance rate. L is an average thickness of a film (μm)). The anti-reflection film comprises a silicon nitride film made of a silicon nitride and a silicon oxide film made of a silicon oxide. The silicon oxide film is formed at a light incidence side of the silicon nitride film or made of a mixed crystal of a silicon nitride and a silicon oxide.

Description

  The present invention relates to a solar cell module and a solar cell, and more specifically, a solar cell having a light trapping film and an antireflection film that can efficiently introduce incident light into the solar cell to increase power generation efficiency. The present invention relates to a module and a solar battery cell.

  A schematic view (cross-sectional view) of a conventional silicon crystal solar cell module is shown in FIG. A protective glass (also referred to as cover glass) 201 on the surface uses tempered glass in consideration of impact resistance, and a sealing material 202 (usually also referred to as a resin or filler mainly composed of ethylene vinyl acetate copolymer). In order to improve the adhesion to the surface, one surface is provided with an uneven pattern by embossing.

  Moreover, the uneven | corrugated pattern is formed inside (namely, the lower surface of the protective glass 201 in FIG. 2), and the surface of the solar cell module 200 is smooth. Further, a sealing material 202 and a back film 204 for protecting and sealing the solar battery cell 100 and the tab wire 203 are provided below the protective glass 201 (see, for example, Non-Patent Document 1).

  However, in the conventional solar cell module described above, since the difference in refractive index between the solar cell 100 and the sealing material 202 is large, there is a problem that light reflection occurs at the cell-sealing material interface and light cannot be used efficiently.

  It has long been known that there is a moth-eye (insect's eye) structure as one of the methods for efficiently taking in external light from all angles including an oblique direction while reducing reflection loss. This is a technology that efficiently incorporates external light by reducing the reflection loss by forming a structure in which transparent objects such as fine cones, triangular pyramids, and quadrangular pyramids are regularly arranged on the surface of the film at a scale of 100 nm. (For example, see Non-Patent Document 2).

  Although the above-mentioned minute-eye structure is considered to be a very effective technique for solar cells, when it is provided in the outermost layer of a solar cell, it will be exposed outdoors for a long period of time and will be contaminated. There is a risk of blocking. Moreover, in order to avoid this, when the both-eye structure is provided on the light incident side inside the module with a normal resin material, the refractive index difference from the sealing material sealing the solar battery cell is small, so that the efficiency It was not possible to take in external light well, and it has hardly been used in the past. Therefore, Patent Document 1 discloses an improved version of this applied to a solar cell module.

  In Patent Document 1, one surface is smooth, and the other surface is formed by laying a large number of fine convex portions (conical shape or polygonal pyramid shape having substantially the same shape), and has a refractive index of 1.4 or more and is transparent. An optical film (light trapping film) has been proposed.

  It has a fine uneven shape that is characteristic of light trapping films. In addition, as a material for obtaining optical contact with solar cells, it has flexibility in the manufacturing process and is unique to light trapping films. And it is necessary to follow the unevenness | corrugation of a photovoltaic cell. A polymer material is suitable as a material having such properties, but the required refractive index (1.55 to 2.40) exceeds the range (approximately 1.7) that can be obtained with a normal polymer material. ing. For this reason, in patent document 1, the high refractive index for exhibiting the flexibility required for a process and the original property of a light trapping film is realizable by the organic-inorganic hybrid material using titanium tetraalkoxide. .

JP 2005-101513 A

Yasuhiro Sasakawa, “Solar Power Generation”-Latest Technology and System, 2000, CMC Corporation Hiroshi Toyoda; “Non-reflective periodic structure”, Optics, Vol. 32, No. 8, p. 489 (2003)

  However, the organic-inorganic hybrid material using titanium tetraalkoxide, which is the material of the light trapping film proposed in Patent Document 1, can be hydrolyzed under high temperature and high humidity to produce highly reactive titanol. The antireflection film of the conventional solar battery cell is mainly formed of silicon nitride, but this titanol erodes silicon nitride. This reaction mechanism is presumed as follows.

  The present invention is intended to alleviate such a problem. Specifically, a light comprising an organic-inorganic hybrid composition using titanium tetraalkoxide in order to improve the light utilization rate in a solar cell module. An object of the present invention is to improve power generation efficiency in a solar battery module having a trapping film and a solar battery cell having an antireflection film containing silicon nitride.

  As a result of intensive studies to solve the above problems, the present inventors have found that an antireflection film containing silicon nitride is <1 even when a light trapping film made of an organic-inorganic hybrid composition using titanium tetraalkoxide is used. > The silicon nitride film is formed by laminating a silicon oxide film on the silicon nitride film, or <2> a one-layer structure composed of a mixed crystal of silicon nitride and silicon oxide. It has been found that a solar cell module and a solar cell having an antireflection film that is not eroded can be provided. That is, the present invention is as follows.

（上記式中、Ｔは透過率、Ｌはフィルム平均厚み（μｍ）である）
上記反射防止膜は、窒化ケイ素からなる窒化ケイ素膜と、酸化ケイ素からなる酸化ケイ素膜と、を有し、且つ上記酸化ケイ素膜は、上記窒化ケイ素膜の光入射側に形成されることを特徴とする太陽電池モジュール。 (1) A solar battery module having a plurality of light-transmitting layers including a light trapping film, and a solar battery cell having an antireflection film on the light incident surface side,
The light trapping film is formed on the light incident side from the antireflection film,
The light trapping film is formed so that a large number of fine convex or concave polygonal pyramids or cones are spread without gaps, and the refractive index is 1.55 to 2.40, and an organic material using titanium tetraalkoxide -The standardized absorbance a composed of an inorganic hybrid composition and represented by the following formula is 0.1 or less at a wavelength of 400 to 1200 nm,

(In the above formula, T is the transmittance, and L is the average film thickness (μm))
The antireflection film includes a silicon nitride film made of silicon nitride and a silicon oxide film made of silicon oxide, and the silicon oxide film is formed on a light incident side of the silicon nitride film. A solar cell module.

(2) The silicon nitride film is composed of Si, N and H, and has a refractive index in the range of 1.60 to 2.70,
The solar cell module according to (1), wherein the silicon oxide film is composed of Si, O, and H and has a refractive index in the range of 1.45 to 1.55.

(3) The solar cell module according to (1) or (2), wherein the silicon oxide film is formed with a thickness of 10 mm or more on a light incident side of the silicon nitride film.
(4) The solar cell module according to (1) or (2), wherein the silicon oxide film is formed with a thickness of 10 to 100 mm on a light incident side of the silicon nitride film.

(5) The silicon nitride film is formed by a plasma CVD method using a mixed gas of SiH ₄ and NH ₃ as a raw material, the mixed gas flow ratio NH ₃ / SiH ₄ is 0.05 to 1.0, and the pressure in the reaction chamber (1) to (4), characterized in that the film is formed under conditions of 0.1 to 2 Torr, a film forming temperature of 300 to 550 ° C., and a plasma discharge frequency of 100 kHz or more. The solar cell module as described in any one.

(6) The silicon oxide film is a mixed gas of SiH ₄ , O ₂ and Ar or He, and the mixed gas flow rate ratio SiH ₄ / O 2 / Ar is obtained by a plasma CVD method using the mixed gas as a raw material. (He) is 1 / 1.5 to 2.0 / 1.5 to 2.0, the pressure in the reaction chamber is 0.005 to 2 Torr, the temperature during film formation is 300 to 550 ° C., for plasma discharge The solar cell module according to any one of (1) to (5), wherein the solar cell module is formed under a condition of a frequency of 100 kHz or more.

（上記式中、Ｔは透過率、Ｌはフィルム平均厚み（μｍ）である）
上記反射防止膜は、窒化ケイ素と酸化ケイ素との混晶体からなることを特徴とする太陽電池モジュール。 (7) A solar cell module having a plurality of light transmissive layers including a light trapping film and a solar cell having an antireflection film on the light incident surface side,
The light trapping film is formed on the light incident side from the antireflection film,
When the plurality of light transmissive layers are layer 1, layer 2,..., Layer m from the light incident side, and the refractive indexes thereof are n1, n2,..., Nm, n1 ≦ n2 ≦・ ・ ・ ・ ≦ nm holds,
The light trapping film is formed so that a large number of fine convex or concave polygonal pyramids or cones are spread without gaps, and the refractive index is 1.55 to 2.40, and an organic material using titanium tetraalkoxide -The standardized absorbance a composed of an inorganic hybrid composition and represented by the following formula is 0.1 or less at a wavelength of 400 to 1200 nm,

(In the above formula, T is the transmittance, and L is the average film thickness (μm))
The solar cell module, wherein the antireflection film is made of a mixed crystal of silicon nitride and silicon oxide.

(8) The antireflection film is made of a mixed crystal of silicon nitride and silicon oxide having a refractive index in the range of 1.45 to 2.70, composed of Si, O, N, and H. The solar cell module according to (7).

(9) The refractive index of the silicon nitride film of the antireflection film or the antireflection film made of the mixed crystal is larger than the refractive index of the light trapping film, as described in (1) or (7) above Solar cell module.

（上記式中、Ｔは透過率、Ｌはフィルム平均厚み（μｍ）である）
上記反射防止膜は、窒化ケイ素からなる窒化ケイ素膜と、酸化ケイ素からなる酸化ケイ素膜と、を有し、且つ上記酸化ケイ素膜は、上記窒化ケイ素膜の光入射側に形成されることを特徴とする太陽電池セル。 (10) An organic-inorganic hybrid using titanium tetraalkoxide, which is formed so that a large number of fine convex or concave polygonal cones or cones are spread without gaps, and the refractive index is 1.55 to 2.40. A solar cell having an antireflection film on the light incident surface side for a solar cell module having a light trapping film composed of a composition and having a normalized absorbance a expressed by the following formula of 0.1 or less at a wavelength of 400 to 1200 nm A battery cell,

(In the above formula, T is the transmittance, and L is the average film thickness (μm))
The antireflection film includes a silicon nitride film made of silicon nitride and a silicon oxide film made of silicon oxide, and the silicon oxide film is formed on a light incident side of the silicon nitride film. A solar battery cell.

（上記式中、Ｔは透過率、Ｌはフィルム平均厚み（μｍ）である）
上記反射防止膜は、窒化ケイ素と酸化ケイ素との混晶体からなることを特徴とする太陽電池セル。 (11) An organic-inorganic hybrid using titanium tetraalkoxide, which is formed so that a large number of fine convex or concave polygonal cones or cones are spread without gaps, and the refractive index is 1.55 to 2.40. A solar cell having an antireflection film on the light incident surface side for a solar cell module having a light trapping film composed of a composition and having a normalized absorbance a expressed by the following formula of 0.1 or less at a wavelength of 400 to 1200 nm A battery cell,

(In the above formula, T is the transmittance, and L is the average film thickness (μm))
The solar cell, wherein the antireflection film is made of a mixed crystal of silicon nitride and silicon oxide.

  According to the present invention, in a solar battery module having a light trapping film made of an organic-inorganic hybrid composition using titanium tetraalkoxide and a solar battery cell having an antireflection film containing silicon nitride, the antireflection film is a light It will not be eroded by titanol derived from the trapping component.

  Further, the present invention is not only for preventing erosion, but also when the organic-inorganic hybrid composition using the titanium tetraalkoxide is used in the light trapping film, the antireflection film of the solar cell as a lower layer thereof has a two-layer structure. (Silicon nitride film and silicon oxide film) Even if the refractive index of the silicon oxide film is smaller than that of the light trapping film, by making the thickness of the silicon oxide film sufficiently smaller than the wavelength, the most efficient sunlight It is possible to provide a solar cell module that obtains a refractive index configuration capable of introducing

1 illustrates one embodiment of the present invention. A solar cell with a light trapping film without aggressively forming a concavo-convex structure. A structural view (cross section) of a conventional solar cell module is shown. One mode when a light trapping film is incorporated in a module. Do not leave the mold film in the module. However, in this figure, connection tab lines are omitted. One mode when a light trapping film is incorporated in a module. Leave the mold film in the module. However, in this figure, connection tab lines are omitted. Light trapping film affixed to solar cells. Here, the mold film is left. The manufacturing process figure which forms a light trapping film in a photovoltaic cell is shown. The manufacturing process figure of the photovoltaic cell (with a texture structure) in the photovoltaic module of this invention is shown. The manufacturing process figure of the photovoltaic cell (without texture structure) in the solar cell module of this invention is shown. The result of the time dependence of deterioration in the moisture resistance test of the solar cell module obtained in the Example is shown.

（上記式中、Ｔは透過率、Ｌはフィルム平均厚み（μｍ）である）
上記反射防止膜は、窒化ケイ素からなる窒化ケイ素膜と、酸化ケイ素からなる酸化ケイ素膜と、を有し、且つ上記酸化ケイ素膜は、上記窒化ケイ素膜の光入射側に形成されることを特徴とする。 Hereinafter, the present invention will be described in detail.
One aspect of the solar cell module of the present invention has a plurality of light transmissive layers including a light trapping film, and a solar cell having an antireflection film on the light incident surface side,
The light trapping film is formed on the light incident side from the antireflection film,
The light trapping film is formed so that a large number of fine convex or concave polygonal pyramids or cones are spread without gaps, and has a refractive index of 1.55 to 2.4, and is an organic material using titanium tetraalkoxide. A standardized absorbance a composed of an inorganic hybrid composition and represented by the following formula (1) is 0.1 or less at a wavelength of 400 to 1200 nm,

(In the above formula, T is the transmittance, and L is the average film thickness (μm))
The antireflection film includes a silicon nitride film made of silicon nitride and a silicon oxide film made of silicon oxide, and the silicon oxide film is formed on a light incident side of the silicon nitride film. And

（上記式中、Ｔは透過率、Ｌはフィルム平均厚み（μｍ）である）
上記反射防止膜は、窒化ケイ素と酸化ケイ素との混晶体からなることを特徴とする。 Another aspect of the solar cell module of the present invention has a plurality of light transmissive layers including a light trapping film, and a solar cell having an antireflection film on the light incident surface side,
The light trapping film is formed on the light incident side from the antireflection film,
When the plurality of light transmissive layers are layer 1, layer 2,..., Layer m from the light incident side, and the refractive indexes thereof are n1, n2,..., Nm, n1 ≦ n2 ≦・ ・ ・ ・ ≦ nm holds,
The light trapping film is formed so that a large number of fine convex or concave polygonal pyramids or cones are spread without gaps, and the refractive index is 1.55 to 2.40, and an organic material using titanium tetraalkoxide -The standardized absorbance a composed of an inorganic hybrid composition and represented by the following formula is 0.1 or less at a wavelength of 400 to 1200 nm,

(In the above formula, T is the transmittance, and L is the average film thickness (μm))
The antireflection film is made of a mixed crystal of silicon nitride and silicon oxide.

The solar cell module of the present invention is a silicon nitride that is a component of the antireflection film by introducing silicon oxide as a component between the light trapping film and the solar cell as an antireflection film of the solar cell. On the other hand, it is possible to prevent erosion by titanol caused by deterioration of a light trapping film made of an organic-inorganic hybrid composition using titanium tetraalkoxide.
More specifically, the antireflection film of the solar battery cell has the following configuration.
<1> A two-layer structure in which a silicon oxide film is laminated on a silicon nitride film, or a <1> one-layer structure made of a mixed crystal of silicon nitride and silicon oxide.

  Further, the present invention is not only for preventing erosion, but also when the organic-inorganic hybrid composition using the titanium tetraalkoxide is used, the antireflection film of the solar cell as the lower layer has a two-layer structure (silicon nitride film). Even if the refractive index of the silicon oxide film is smaller than that of the light trapping film, it is possible to introduce sunlight most efficiently by making the thickness of the silicon oxide film sufficiently thinner than the wavelength. A refractive index configuration can be obtained.

  The best mode for carrying out the present invention will be described below with reference to the drawings. FIG. 3 shows a cross section of a solar cell module using solar cells made of a silicon substrate.

  That is, in the solar cell module 200 of the present invention, in order to efficiently introduce external light entering from all angles into the solar cell with little reflection loss, a plurality of light transmissive layers, that is, antireflection films on the protective glass ( (Not shown), protective glass 201, sealing material 202, mold film (not shown), light trapping film 300, antireflection film (not shown) of solar cell 100, and pn junction layer of solar cell (shown) It is preferable to lower the refractive index from the light incident side in the order of not shown.

  However, it is impossible to obtain such a configuration in consideration of an actual manufacturing process. That is, the antireflection film on the solar battery cell is formed in the solar cell manufacturing process, and is a shallower layer (here, the antireflection film on the protective glass (a film different from the antireflection film on the solar battery cell)) , Protective glass, sealing material, mold film, light trapping film, etc.) are formed in the solar cell module manufacturing process, and therefore it is impossible to obtain a continuous refractive index distribution across the respective layer members.

  Here, the thing-eye structure realizes a continuous equivalent refractive index by a physical shape. However, as can be seen in Non-Patent Document 2, the fine weight shape required there is the wavelength order of light to be introduced. On the other hand, the light trapping film in the present invention does not require a very fine shape, and may be 10 μm or more that allows realistic mold processing. This is because the light trapping film in the present invention uses an optical path, multiple reflection, and retroreflection described in geometric optics rather than obtaining a continuous equivalent refractive index distribution.

  The present invention particularly reduces the reflection loss at the optical interface on the module layer structure depending on the process, the sealing material-solar cell interface of the prior art, and increases the amount of light introduced into the solar cell. Is. Therefore, the most important point of the present invention is to provide a configuration capable of realizing light introduction at the highest efficiency into the pn junction layer of the solar cell with a higher refractive index than that of the sealing material. More specifically, the light introduction effect of the light trapping film is maximized by controlling the refractive index of the antireflection film on the light trapping film and the solar battery cell.

Specifically, the refractive index of the antireflection film on the protective glass is 1.25 to 1.45, and the refractive index of the protective glass, sealing material, mold film and the like is usually 1.45 to 1.55. Something about is used. The light trapping film in the present invention is preferably 1.55 to 2.40.
In the case where the antireflection film in the present invention has a single-layer structure made of a mixed crystal of silicon nitride and silicon oxide, the refractive index of the antireflection film made of the mixed crystal is 1.45 to 2.70.
When the antireflection film in the present invention has a two-layer structure of a silicon nitride film and a silicon oxide film, the refractive index of the silicon oxide film in the present invention is 1.45 to 1.55, and the silicon nitride in the present invention The refractive index of the film is 1.60 to 2.70. As described above, when the antireflection film has a two-layer structure of a silicon nitride film and a silicon oxide film, the refractive index of the silicon oxide film formed on the light incident side of the silicon nitride film is that of the silicon nitride film. It becomes smaller than the refractive index. Therefore, it is possible to introduce light with high efficiency by making the thickness of the silicon oxide film much smaller than the wavelength, preferably by setting it to 1/4 or less of the wavelength. Details will be described later. Theoretically, as described above, it is desirable that the refractive index increases in order from the light incident side to the solar battery cell, and the relationship is

というように、ひとつの層の屈折率は、その上下の屈折率に依存させると最も効率よく光が導入しうる。

As described above, when the refractive index of one layer depends on the upper and lower refractive indexes, light can be introduced most efficiently.

  In particular, in order to maximize the effects of the present invention, ideally, it is desired that the refractive index of the light trapping film and that of the antireflection film of the solar battery cell be the same. However, in reality, in the organic-inorganic hybrid composition using the titanium tetraalkoxide, the refractive index exceeding 1.75 becomes remarkably unstable. With the conventional method for forming an antireflection film for solar cells, It is impossible to optically make the light trapping film and the solar cell antireflection film optically identical.

  In the present invention, the degree of freedom of the refractive index is particularly increased in terms of lowering the refractive index by using silicon oxide as a constituent component as the antireflection film of the solar battery cell.

(1) Light Trapping Film First, light trapping which is one of the features of the present invention will be described.
The light trapping film in the present invention is formed such that a large number of fine convex or concave polygonal pyramids or cones are spread without gaps, and the refractive index is 1.55 to 2.40, and titanium tetraalkoxide is used. It is composed of an organic-inorganic hybrid composition.

  In the present invention, the light trapping film preferably has a value of the film normalized extinction coefficient a represented by the above formula (1) of 0.1 to 0.1 when the wavelength of incident light is 400 to 1200 nm. When a is in the above range, light transmittance comparable to that of protective glass, sealing material, etc. can be obtained, and light absorption loss due to the light trapping film need not be taken into consideration.

  In addition, the light transmittance of T is the light transmittance of the material itself in the state without the unevenness | corrugation of a light trapping film. The film average thickness of L is the average thickness of the light trapping film material.

  The light trapping film in the present invention is a light trapping film used for a solar cell module, that is, a light trapping film formed so that one side follows the cell surface shape without gaps, and the other side is laid with a large number of fine recesses or projections without gaps. The shape of each of the fine recesses or protrusions is substantially the same cone or polygonal pyramid shape, and its refractive index is 1.55 to 2.40 and is transparent. It is a light trapping film.

In order for external light entering from all angles to be efficiently introduced into the solar cell with little reflection loss, the refractive index of the light trapping film is closer to the light incident surface than the light trapping film, such as a sealing material or a mold film. It is preferable that the refractive index is higher than the refractive index of the layer and lower than the antireflection film of a solar cell, for example, a layer on the side opposite to the light incident surface from the light trapping film. The specific refractive index is preferably 1.55 to 2.40, more preferably 1.6 to 2.20.
A feature of the present invention is that the optimum refractive index configuration can be adjusted from both the light trapping film and the solar cell antireflection film.

  For example, the protective glass which is the outermost layer, the sealing material on the lower layer (reverse light incident surface side), the solar cell pn junction layer (n layer, p layer, etc.), etc., are difficult to change the refractive index. However, being able to adjust with the light trapping film and antireflection film as the intermediate layer makes it easy to realize a refractive index configuration that increases from the light incident side.

  Further, in the present invention, a light trapping film with a mold film used for a solar cell module, that is, the light trapping film and the fine concave or convex portion side of the light trapping film are complementary to the fine concave or convex portion (no gap). A mold film (a mold for forming a concave or convex portion of a light trapping film) in which a large number of fine convexities or concave portions that are completely meshed and bonded are formed without gaps, and the refractive index thereof is smaller than that of the light trapping film. It is also possible to use a light trapping film with a smooth mold film (see FIG. 4).

  One side of the light trapping film follows the irregularities on the surface of the solar battery cell without any gaps, and is usually laminated on the solar battery cell 100, and the mold film used on the fine concave or convex surface of the other side of the light trapping film 300 301 is left without being removed (FIG. 4), or the mold film is removed and the sealing material 202 is laminated so as to fill the irregularities of the light trapping film 300 without gaps (see FIG. 4). FIG. 3).

  Each of the fine recesses or protrusions formed without gaps so as to be spread on one side of the light trapping film has a fine cone shape or a fine polygonal cone shape. In the non-reflective structure in Non-Patent Document 2, it is advantageous that the apex angle is narrow, but in the present invention, the light trapping film is sealed in a resin (sealing material), and further close to the solar battery cell, The situation is different.

  In order to efficiently introduce incident light from any angle into the solar cell, it is advantageous that the apex angle is narrow, but when there is a reflection loss at the interface between the light trapping film and the solar cell, the apex angle is If it is too narrow, the reflected light leaks to the outside again. Therefore, in order to reflect the reflected light again by the light trapping film and return it to the solar battery cell, 90 degrees of the apex angle is ideal. If the apex angle is 90 degrees, it can be said that the angle is the best in terms of performance and processing accuracy.

  According to Non-Patent Document 2, the size of the base is a value obtained by dividing the shortest wavelength to be used by the refractive index of the material. For example, when the refractive index is 2.0, the solar cell module has 175 nm. It will be about. However, in order to obtain such a fine structure, the processing method is also limited.

  In the present invention, such an ultrafine structure is not required. The most ideal light trapping film fine shape of the present invention is a corner cube that retroreflects incident light in the same direction, but it is difficult to realize the concept of a corner cube due to a difference in realistic refractive index. Therefore, when regular polygonal pyramids are spread out, when one polygonal pyramid escapes the reflected light from the solar cells to the outside of the light trapping film (specifically, in the mold film), it again by the neighboring polygonal pyramids. It is aimed to be taken inside the light trapping film. Based on such a concept, it is designed so that a desired effect can be obtained even with a fine uneven shape having a size and shape that can be sufficiently machined.

  In the light trapping film of the present invention, the light trapping film is considered by dividing it into a pedestal portion and an uneven portion. As shown in FIG. 5, since the pedestal portion 303 needs to be embedded following the uneven shape of the solar battery cell, the thickness must be equal to or greater than the unevenness of the solar battery cell. Usually, the surface of the solar battery cell is provided with a texture structure, and the depth thereof is 0 to 20 μm. On the other hand, the height 302 of the fine recesses or projections formed so as to be laid on the light trapping film regularly and without gaps, which is an essential part, is 1 to 100 μm mainly due to processing requirements.

  In addition, the light trapping film having a refractive index of 1.55 to 2.40 follows the unevenness of the solar battery cell as described above, and the original fine uneven shape of the light trapping film must be transferred, so that it is semi-cured. It is important to obtain a resin composition in a state, and an organic-inorganic hybrid composition using titanium tetraalkoxide as a material for a light trapping film having a high refractive index and exhibiting shape transferability.

  The light trapping film in this invention can be formed and manufactured on the antireflection film of the solar cell having the antireflection film, using the film-like resin composition layer comprising the organic-inorganic hybrid composition. One method will be described with reference to FIG.

  As shown in FIG. 6 (a), from the organic-inorganic hybrid composition in a semi-cured state sandwiched between a base film 304 such as PET as a base material and a separator film 306 such as PP. When the resin composition layer 305 to be formed is attached to the solar battery cell 100 (an antireflection film is not shown), the separator film 306 is first peeled off.

Next, as shown in FIG. 6B, a semi-cured resin composition layer 305 is attached to the solar battery cell 100 with the base film 304 attached, using a vacuum laminator.
Thereafter, as shown in FIG. 6 (c), the base film 304 is peeled off, and the mold film 301 is placed on the semi-cured resin composition layer 305. Further, as shown in FIG. 6 (d), a vacuum laminator is further provided. Then, the fine uneven shape is transferred to obtain the light trapping film 300a (before curing).
After obtaining the light trapping film 300a before curing, the light trapping film 300a in a semi-cured state is further cured with light or heat to obtain a light trapping film 300b (after curing). After curing, the mold film 301 may be left as it is, and may be sandwiched between the protective glass 201, the sealing material 202, and the back film 204 to form a module (see FIG. 4).

  Further, as shown in FIG. 6E, after the mold film 301 is peeled off from the state of FIG. 6D, the module is sandwiched between the protective glass 201, the sealing material 202, and the back film 204 as shown in FIG. May be.

  At this time, if the texture structure of the solar battery cell is 10 μm deep and the depth of the unevenness of the mold film is 10 μm, the light trapping film before lamination needs to have a thickness of at least 20 μm. In other words, the former is a pedestal portion and the latter is a convex or concave polygonal pyramid or cone portion.

A mold film (a mold film serving as a mold for forming a convex or concave polygonal pyramid or conical portion of a light trapping film) can be produced by the method described in JP-A-2002-225133. The shape of the mold film is such that a large number of fine convex or concave polygonal pyramids or cones are spread on the light incident surface without any gaps on the light trapping film.
Specific production examples of the mold film will be described later in Examples.
The refractive index of the light trapping film in the present invention is not significantly different from the semi-cured state and after being cured (after being formed into a solar module).

In order to obtain a high refractive index, the material of the light trapping film in the present invention is an organic-inorganic hybrid composition using a sol-gel method. The essential ingredients in the sol-gel method are:
(R ¹ ) _n M- (OR ² ) _m
In the present invention, Ti— (OR) _{4 is used.}

The titanium tetraalkoxide shown by these is used as at least one part. Complementarily, M may be a metal selected from Zn, Zr, Al, Si, Sb, Be, Cd, Cr, Sn, Cu, Ga, Mn, Fe, Mo, V, Ge, W, and Ce. Absent.

  R has a plurality of R1 and R2 having 1 to 10 carbon atoms bonded to M, but each may be the same or different. n is an integer of 0 or more, m is an integer of 1 or more, and n + m is equal to the valence of M.

  When obtaining the organic-inorganic hybrid composition by the sol-gel method, the metal alkoxide to be used may be one kind or plural kinds as long as at least titanium tetraalkoxide is used.

  In order to obtain an organic-inorganic hybrid composition by using the sol-gel method, a metal alkoxide (including at least titanium tetraalkoxide), water, and an acid (or alkali) catalyst are added to a resin composition in a solution state. It is obtained by applying to the material, volatilizing the solvent and heating. However, depending on the reactivity of the metal alkoxide chosen, water and / or acid (or alkali) catalysts may not be required. The heating temperature also depends on the reactivity of the metal alkoxide. A highly reactive material such as Ti requires neither water nor a catalyst, and the heating temperature may be about 100 ° C.

  In the present invention, the (-MO-) three-dimensional structure is not necessarily required as long as a high refractive index can be realized. In particular, the three-dimensional structure of titanium oxide becomes a semiconductor so as to be used in a photocatalyst. However, this structure is inconvenient in terms of photodegradation, and therefore, a technique using in combination with another metal alkoxide is effective in order to intentionally break the three-dimensional structure.

(2) Antireflection film As described above, the light trapping film composed of an organic-inorganic hybrid composition using titanium tetraalkoxide has an optical antireflection effect. Therefore, when a silicon nitride film made of silicon nitride composed of Si, N and H is provided on the solar battery cell, the silicon nitride and the light trapping film are in direct contact with each other, thereby contacting the N atom and the Ti atom. Substitution of N atoms occurs, eroding silicon nitride and losing optical performance.

  In order to solve this problem, in the present invention, the antireflection film has a two-layer structure in which a silicon oxide film is laminated on a <1> silicon nitride film, or <2> a mixture of silicon nitride and silicon oxide. By adopting a single-layer structure made of a crystal, it is possible to prevent contact between N atoms of silicon nitride and Ti atoms of the light trapping film.

  In order to realize a two-layer structure in which a silicon oxide film is laminated on the above <1> silicon nitride film, in the present invention, a silicon nitride film made of silicon nitride is first formed on a semiconductor layer of a pn junction layer, Thereafter, a silicon oxide film containing silicon oxide is formed.

  In a crystalline silicon solar cell, a method of forming silicon nitride on the semiconductor layer on the light incident surface side by, for example, plasma CVD is common. On the other hand, although silicon oxide is generally used in LSI in the semiconductor industry (for example, JP 2007-12119 A, JP 10-929810 A, JP 2007-129119 A, etc.) When the structure up to the solar cell module is targeted, there is almost no application to solar cells.

  Since the refractive index of silicon oxide is about 1.45 to 1.55, it may be lower than that of the light trapping film. In this case, considering the module structure, it is not optically optimal. Therefore, the thickness of the silicon oxide film is deteriorated by direct contact between the silicon nitride and the light trapping film in the silicon nitride film, that is, N atoms are replaced by contact of N atoms and Ti atoms, and silicon nitride is eroded. The minimum film thickness that can suppress the phenomenon is sufficient, and if the film thickness can be realized, the manufacturing time can be suppressed to the minimum.

  In addition, as a film thickness which can suppress the phenomenon that silicon nitride is eroded, 10 mm or more is preferable, and 10 mm or more and 100 mm or less is more preferable. When the film thickness is 10 mm, the deterioration of the silicon nitride in the silicon nitride film due to the light trapping film, that is, the phenomenon that N atoms are replaced by contact of N atoms and Ti atoms and silicon nitride is eroded can be suppressed. Is possible.

  On the other hand, since the silicon nitride film can also be formed by plasma CVD, the silicon nitride film and the silicon oxide film can be continuously formed.

In another aspect of the antireflection film according to the present invention, <2> in the case of a one-layer structure composed of a mixed crystal of silicon nitride and silicon oxide, silicon nitride and silicon oxide are formed on the semiconductor layer of the pn junction layer. A film made of a mixed crystal is formed. As described above, the mixed crystal has a refractive index of 1.45 to 2.70.
On the other hand, a film made of a mixed crystal can also be formed by plasma CVD.

(3) Manufacturing method of solar cell module Hereinafter, the manufacturing method of a solar cell module is demonstrated.

As long as the solar cell used in the present invention has the antireflection film of the present invention on the light incident surface side, it is effective in any form as long as it is a generally manufactured solar cell. A structure of a solar battery cell for further improving efficiency as a battery module will be described with reference to the drawings including manufacturing steps.
FIG. 7 is a schematic diagram of a cross section of a silicon solar cell, showing the main manufacturing steps in order of steps (a) to (f). FIG. 7F shows a completed state as a solar battery cell.

  FIG. 8 shows the main manufacturing steps (a), (b), and (f) in the order of steps when the texture structure is not formed. The manufacturing process shown in FIG. 8 is the same as the manufacturing process shown in FIG. 7 except that the part forming the texture structure is different. Therefore, the steps from the texture formation to the printing and drying of the electrodes are omitted (corresponding portions in FIGS. 7C to 7E), and FIG. 8F, which is a completed state when the texture structure is not formed, is used. Indicated.

  The solar cell currently mass-produced is a silicon crystal solar cell using a polycrystalline silicon substrate or a single crystal silicon substrate, and a p-type silicon substrate having a thickness of several hundred μm is sometimes used. Many. In the following description, a p-type silicon crystal substrate will be described as an example.

  In the next step (FIG. 7B) using the p-type silicon substrate 101 shown in FIG. 7A, the damage layer on the silicon surface generated when slicing from the cast ingot is, for example, several to 20 wt%. After removing 10 to 20 μm thick with caustic soda solution or carbonated caustic soda solution, anisotropic etching is performed with a solution obtained by adding IPA (isopropyl alcohol) to the same alkali low concentration solution to form the texture structure 102 so that the silicon surface is exposed. To do. In general, as described in, for example, Japanese Patent No. 3602323, a solar battery cell can achieve high efficiency by forming a texture structure on the surface side.

Subsequently, in FIG. 7C, several tens of minutes of treatment is performed at 800 to 900 ° C. in a mixed gas atmosphere of phosphorus oxychloride (POCl ₃ ), nitrogen and oxygen to form the n-type layer 103 uniformly on the surface. To do. The n-type layer 103 uniformly formed on the silicon surface has a sheet resistance range of 30 to 80Ω / □, and good electric characteristics of the solar battery cell can be obtained. At this time, since the n-type layer 103 is formed on the entire surface of the substrate, it is necessary to remove the n-type layer 103 on the back surface side. Therefore, for example, in order to protect the n layer on the light incident surface side, after depositing and drying a polymer resist paste by a screen printing method, an n-type layer formed on an undesired silicon surface such as the back surface of silicon is 20 wt%. It is removed by dipping in a potassium hydroxide solution for several minutes, and the resist is removed with an organic solvent.

Further, FIG. 7D illustrates the formation of the antireflection film 104 having a two-layer structure. A uniform thickness 104a of a silicon nitride film (a part of a two-layer antireflection film) made of silicon nitride is formed on the n-type layer 103 surface. For example, in the silicon nitride film 104a, the mixed gas flow ratio NH ₃ / SiH ₄ is 0.05 to 1.0 and the reaction chamber pressure is 0.1 by plasma CVD using a mixed gas of SiH ₄ and NH ₃ as a raw material. ˜2 Torr, film forming temperature is 300 to 550 ° C., plasma discharge frequency is 100 kHz or more, and the optimum refractive index range of the antireflection film is 1.60 to 2.70, more preferably Is 1.8 to 2.7, and the range of film thickness is 70 to 90 nm.

Further, a silicon oxide film 104b made of silicon oxide is formed on the surface of the silicon nitride film 104a. For example, the mixed gas flow rate ratio SiH ₄ / O ₂ / Ar (He) is 1 / 1.5-2 to 2 by a plasma CVD method using SiH ₄ , O ₂ and Ar or He as a raw material. 0 / 1.5 to 2.0, the reaction chamber pressure is 0.005 to 2 Torr, the temperature during film formation is 300 to 550 ° C., and the frequency for plasma discharge is 100 kHz or more. The range is 10 to 100 inches. The refractive index is 1.45 to 1.55.

  Next, in FIG. 7E, the surface electrode paste 105 is attached and dried by screen printing. In this case, the surface electrode paste 105 is formed on the antireflection film 104 (specifically, the silicon oxide film 104b). Next, the back surface aluminum paste 106 is printed and dried on the back side as well as the front side.

  FIG. 7F shows a state where the electrode is baked to complete a solar battery cell. When baked for several minutes in the temperature range of 600 to 900 ° C., while the antireflection film, which is an insulating film, is melted by the glass material contained in the surface silver paste on the surface side, and the silicon surface is also partially melted Electrical contact is made possible by the silver material forming contact portions with the silicon and solidifying. This phenomenon ensures conduction between the surface silver electrode and silicon. On the other hand, on the back side, aluminum in the aluminum paste reacts with silicon on the back side to form a p + layer and form a BSF (Back Surface Field) layer 109 that improves power generation capability.

Subsequently, the solar cell module of the present invention can be obtained by sticking the light trapping film of the present invention on the solar cell shown in FIG.
Even when the antireflection film is made of a mixed crystal, a mixed gas of SiH ₄ , NH ₃ and O ₂ is used as a raw material as a raw material, and the antireflection film is formed by a plasma CVD method in the same manner as the silicon nitride film. Can be formed.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Example 1
<Manufacture of solar cells>
As described above, an n-type layer was formed on a p-type silicon substrate by a normal method, and an antireflection film was formed on the n-type layer under the following conditions.

  Specifically, after using the p-type silicon substrate 101 shown in FIG. 7 (a) and removing the damaged layer on the silicon surface generated when slicing from the cast ingot with a 5 wt. An anisotropic etching was performed with a solution obtained by adding 10 wt% of IPA (isopropyl alcohol) to the concentration solution, and the texture structure 102 was formed so that the silicon 111 surface appeared.

Subsequently, as shown in FIG. 7C, the n-type layer 103 is uniformly formed on the surface by performing a treatment at 800 ° C. for 30 minutes in a mixed gas atmosphere of phosphorus oxychloride (POCl ₃ ), nitrogen, and oxygen. The layer thickness was 50 nm. The sheet resistance of the n-type layer 103 uniformly formed on the silicon surface was 80Ω / □. At this time, since the n-type layer 103 is formed on the entire surface of the substrate, the following treatment was performed in order to remove the n-type layer 103 on the back surface side. In order to protect the n layer on the light incident surface side, after depositing and drying a polymer resist paste by a screen printing method, an n-type layer formed on an undesired silicon surface such as a silicon back surface is coated with 20 wt% potassium hydroxide. The resist is removed by dipping in a solution for 5 minutes, and the resist is removed with an organic solvent.

Further, in FIG. 7D, a uniform thickness of the silicon nitride film 104a made of silicon nitride is formed on the surface of the n-type layer 103. Specifically, by the plasma CVD method using a mixed gas of SiH ₄ and NH ₃ as a raw material, the mixed gas flow rate ratio NH ₃ / SiH ₄ is 4 / 3.3, the reaction chamber pressure is 10 ⁻³ Torr, A silicon nitride film having a refractive index of 1.9 and a film thickness of 120 nm was formed under the conditions of a film temperature of 500 ° C. and a plasma discharge frequency of 100 kHz.

Further, a silicon oxide film 104b made of silicon oxide is formed on the surface of the silicon nitride film 104a under the following conditions. The mixed gas flow ratio SiH ₄ / O ₂ / Ar is 1/1/1 and the pressure in the reaction chamber is 10/1 by a plasma CVD method using SiH ₄ , O ₂ and Ar or He as a raw material. ^A silicon oxide film having a refractive index of 1.49 and a thickness of 50 mm was formed under the conditions of ⁻³ Torr, film forming temperature of 600 ° C., and plasma discharge frequency of 100 kHz.

  Next, as shown in FIG. 7E, the surface electrode paste 105 is attached and dried by a screen printing method. In this case, the surface electrode paste 105 is formed on the silicon oxide film 104b. Next, the back surface aluminum paste 106 is printed and dried on the back side as well as the front side.

  FIG. 7F shows a state where the electrode is baked to complete a solar battery cell. The silver material is baked for 1 minute in the temperature range of 800 ° C., and the antireflection film as the insulating film is melted by the glass material contained in the surface silver paste on the surface side, and further the silicon surface is partially melted. Made electrical contact by forming a contact with silicon and solidifying. This phenomenon ensures conduction between the surface silver electrode and silicon. On the other hand, the BSF (Back Surface Field) layer 109 is formed on the back surface side, in which the aluminum in the aluminum paste reacts with the silicon on the back surface to form a p + layer and improve the power generation capability.

<Manufacture of solar cell modules>
Then, the following light trapping film in this invention is affixed on the photovoltaic cell shown in FIG.7 (f). The structure can be referred to FIG. 1 (in FIG. 1, a light trapping film is attached on the solar battery cell shown in FIG. 8 (f)).
1) Preparation of photosensitive resin composition for mold film Acrylic acrylate as binder resin (trade name: Hitaroid HA7885, manufactured by Hitachi Chemical Co., Ltd.): 50 parts by mass, EO-modified phenol A dimethacrylate as a crosslinkable monomer (Trade name: FANCLIL FA-321M, manufactured by Hitachi Chemical Co., Ltd.): 50 parts by mass, and 1-hydroxy-cyclohexyl-phenyl ketone as a photoinitiator (trade name: IRGACURE 184, Ciba Specialty Chemicals, Inc. )): 3.0 parts by mass was dissolved in methyl ethyl ketone as an organic solvent to obtain a varnish (photosensitive resin composition). A film of this varnish was formed on a silicon wafer so as to have a thickness of about 5000 mm, and the refractive index was measured with an ellipsometer to be 1.48.

2) Production of a mold film One to two drops of the photosensitive resin composition is dropped on a mold having an effective area of 155 mm square, a base of 20 μm, and a height of 10 μm without any gaps, A polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., trade name: A-4300) subjected to a double-sided easy adhesion treatment with a thickness of 50 μm was placed thereon. Air bubbles were removed with a roller so that air bubbles did not enter between the photosensitive resin composition and the PET film, and UV light was irradiated from the PET side. By removing the PET film from the mold, a concave quadrangular pyramid film was obtained. The square film dimensions of the obtained mold film are the same as the mold.
The refractive index of the mold film was 1.5.

3) Preparation of resin composition for light trapping film After introducing air gas into a reaction vessel equipped with a stirrer, thermometer, cooling pipe and air gas introduction pipe, 115 parts by mass of 2-hydroxyethyl acrylate (hydroxyl group) : 1.0 equivalent), polycarbonate diol composed of 1,9-nonanediol, 2-methyl-1,8-octanediol and diphenyl carbonate (manufactured by Kuraray Co., Ltd., trade name: PNOC-2000, number average molecular weight: about 2000) 4000 parts by mass (hydroxyl group: 4.0 equivalents), hydroquinone monomethyl ether (manufactured by Wako Pure Chemical Industries, Ltd.) 0.5 parts by mass, dibutyltin dilaurate (manufactured by Tokyo Fine Chemicals Co., Ltd., trade name: L101) 5.0 parts by mass and 4000 parts by mass of toluene were charged, and the temperature was raised to 70 ° C. Incubated for 4 minutes, 650 parts by mass of 4,4′-dicyclohexylmethane diisocyanate (manufactured by Sumitomo Bayer Urethane Co., Ltd., trade name: Desmodur W) (isocyanate group: 5.0 equivalents) and toluene 300 A part by mass of the mixed liquid was uniformly dropped at 70 to 75 ° C. over 3 hours to be reacted.

  After completion of the dropwise addition, the reaction was carried out by incubating at 70 to 75 ° C. for about 5 hours. After confirming that the isocyanate had disappeared by IR measurement, the reaction was terminated. Furthermore, 30 parts by mass of Irgacure-184 (manufactured by Ciba Geigy), 8000 parts by mass of titanium tetraisopropoxide, 1600 parts by mass of FA-712HM manufactured by Hitachi Chemical Co., Ltd., PET manufactured by Daiichi Kogyo Seiyaku Co., Ltd. 3-3 parts by mass and 3000 parts by mass of diethanolamine were added and stirred and dissolved to obtain a urethane UV curable resin composition.

4) Production of light condensing (semi-cured) film The urethane-based UV curable resin composition for light trapping film is applied onto a PET film (base material) with an applicator, and hot air convection drying at 80 to 100 ° C. The film was passed through and dried for about 10 minutes to obtain a semi-cured film. On the coating film, a semi-cured film was protected with a PP film as a separator film.

5) Formation of concavo-convex shape of light trapping film The separator film of the light trapping film was peeled off and placed on the solar cell obtained above, and then laminated using a vacuum laminator. Furthermore, the PET, which is the base material of the semi-cured film, is peeled off, the uneven surface of the mold film is pressed against the semi-cured film, and further passed through a vacuum laminator, and the fine uneven shape is semi-cured film Transcribed to. At this time, the light trapping film was formed with a square pyramid having a base of 20 μm and a height of 10 μm without any gaps, and the thickness of the pedestal portion was 10 μm.

Further, the film was cured by irradiating light with an exposure device to obtain a light trapping film. The vacuum laminator was manufactured by Meiki Seisakusho Co., Ltd. The lamination and shape transfer conditions were 75 ° C., the pressure was 0.4 MPa, and the time was 45 seconds. The exposure machine was a high-pressure mercury lamp, and the exposure conditions were 1000 mJ / cm ² .
The refractive index of the light trapping film was 1.7.

(Example 2)
In the solar cell module obtained in Example 1, except that the light trapping film is not provided, the antireflection film is not provided with the silicon oxide film, and the thickness of the silicon oxide film is changed to 5 mm, 10 mm, and 100 mm Produced the following solar cell modules in the same manner, and evaluated the short-circuit current density.
The short-circuit current density was evaluated using a Wacom solar simulator and a Wacom IV measuring instrument. With an IV measuring instrument, short-circuit current density, open-circuit voltage, fill factor, and conversion efficiency can be measured at a time.
(1) Reference: No light trapping film attached (2) No silicon oxide film, only silicon nitride film (120 nm) configuration (3) Silicon oxide film (5 mm) formed, silicon nitride film (120 nm) Configuration (4) Formation of silicon oxide film (10 nm) and configuration of silicon nitride film (120 nm) (5) Formation of silicon oxide film (100 nm) and configuration of silicon nitride film (120 nm)

By attaching the light trapping film, the short-circuit current density was improved, increased by 0.5 mA / cm ² compared to the case without attachment, and the conversion efficiency was improved by 0.3 points (%). Recognize.

  In FIG. 9, in order to confirm the effect of the silicon oxide film, the time dependency of deterioration was examined in accordance with JIS-C8917 moisture resistance test B-2 using the film thickness of the silicon oxide film as a parameter. Show.

  As shown in FIG. 9, in terms of moisture resistance, the film thickness of the silicon oxide film is suppressed to 5 mm, but the deterioration is suppressed, but a film thickness of 10 mm is required to be comparable to the moisture resistance level where the light trapping film is not attached. It was confirmed that it was necessary.

  According to the present invention, it is possible to provide a solar battery module and a solar battery cell in which deterioration of moisture resistance is suppressed and light utilization (power generation efficiency) is improved.

100: solar cell 101: p-type silicon substrate 102: texture structure 103: n-type layer 104: antireflection film 104a: silicon nitride film 104b: silicon oxide film 105: silver paste for front electrode 106: aluminum paste 107 for back electrode : Front electrode 108: Back electrode 109: p + layer (BSF: Back Surface Field layer)
200: Solar cell module 201: Protective glass (cover glass)
202: Sealing material 203: Tab wire 204: Back film 300: Light trapping film 300a: Light trapping film 300b before curing: Light trapping film 301 after curing 301: Mold film 302: Light trapping film, uneven portion 303: Light trapping Film, pedestal portion 304: PET film (base material)
305: Semi-cured resin composition layer 306: PP film (separator)

Claims (11)

A solar cell module having a plurality of light transmissive layers including a light trapping film, and a solar cell having an antireflection film on the light incident surface side,
The light trapping film is formed on the light incident side from the antireflection film,
The light trapping film is formed so that a large number of fine convex or concave polygonal pyramids or cones are spread without gaps, and the refractive index is 1.55 to 2.40, and an organic material using titanium tetraalkoxide -The standardized absorbance a composed of an inorganic hybrid composition and represented by the following formula is 0.1 or less at a wavelength of 400 to 1200 nm,

(In the above formula, T is the transmittance, and L is the average film thickness (μm))
The antireflection film has a silicon nitride film made of silicon nitride and a silicon oxide film made of silicon oxide, and the silicon oxide film is formed on a light incident side of the silicon nitride film. A solar cell module. The silicon nitride film is composed of Si, N and H and has a refractive index in the range of 1.60 to 2.70,
The solar cell module according to claim 1, wherein the silicon oxide film is composed of Si, O, and H and has a refractive index in a range of 1.45 to 1.55.   The solar cell module according to claim 1 or 2, wherein the silicon oxide film has a thickness of 10 mm or more on a light incident side of the silicon nitride film.   The solar cell module according to claim 1 or 2, wherein the silicon oxide film has a thickness of 10 to 100 mm on a light incident side of the silicon nitride film. When the silicon nitride film is formed by a plasma CVD method using a mixed gas of SiH ₄ and NH ₃ as a raw material, the mixed gas flow ratio NH ₃ / SiH ₄ is 0.05 to 1.0, and the reaction chamber pressure is 0. 5. The film is formed under the conditions of 1 to 2 Torr, a film forming temperature of 300 to 550 ° C., and a plasma discharge frequency of 100 kHz or more. Solar cell module. The silicon oxide film is a mixed gas of SiH ₄ , O ₂ , Ar or He, and the mixed gas flow ratio SiH ₄ / O 2 / Ar (He) is obtained by a plasma CVD method using the mixed gas as a raw material. 1 / 1.5 to 2.0 / 1.5 to 2.0, reaction chamber pressure 0.005 to 2 Torr, film forming temperature 300 to 550 ° C., plasma discharge frequency 100 kHz It forms under the above conditions, The solar cell module as described in any one of Claims 1-5 characterized by the above-mentioned. A solar cell module having a plurality of light transmissive layers including a light trapping film, and a solar cell having an antireflection film on the light incident surface side,
The light trapping film is formed on the light incident side from the antireflection film,
When the plurality of light transmissive layers are layer 1, layer 2,..., Layer m from the light incident side, and the refractive indexes thereof are n1, n2,..., Nm, n1 ≦ n2 ≦・ ・ ・ ・ ≦ nm holds,
The light trapping film is formed so that a large number of fine convex or concave polygonal pyramids or cones are spread without gaps, and the refractive index is 1.55 to 2.40, and an organic material using titanium tetraalkoxide -The standardized absorbance a composed of an inorganic hybrid composition and represented by the following formula is 0.1 or less at a wavelength of 400 to 1200 nm,

(In the above formula, T is the transmittance, and L is the average film thickness (μm))
The solar cell module, wherein the antireflection film is made of a mixed crystal of silicon nitride and silicon oxide. The antireflection film is made of a mixed crystal of silicon nitride and silicon oxide having a refractive index in the range of 1.45 to 2.70, composed of Si, O, N, and H. 8. The solar cell module according to 7.   The solar cell module according to claim 1 or 7, wherein a refractive index of the silicon nitride film of the antireflection film or an antireflection film made of the mixed crystal is larger than a refractive index of the light trapping film. An organic-inorganic hybrid composition using titanium tetraalkoxide, which is formed so that a large number of fine convex or concave polygonal pyramids or cones are spread without gaps, and the refractive index is 1.55 to 2.40. A solar cell having an antireflection film on the light incident surface side for a solar cell module having a light trapping film having a light-trapping film having a normalized absorbance a of 0.1 or less at a wavelength of 400 to 1200 nm represented by the following formula: There,

(In the above formula, T is the transmittance, and L is the average film thickness (μm))
The antireflection film has a silicon nitride film made of silicon nitride and a silicon oxide film made of silicon oxide, and the silicon oxide film is formed on a light incident side of the silicon nitride film. A solar battery cell. An organic-inorganic hybrid composition using titanium tetraalkoxide, which is formed so that a large number of fine convex or concave polygonal pyramids or cones are spread without gaps, and the refractive index is 1.55 to 2.40. A solar cell having an antireflection film on the light incident surface side for a solar cell module having a light trapping film having a light-trapping film having a normalized absorbance a of 0.1 or less at a wavelength of 400 to 1200 nm represented by the following formula: There,

(In the above formula, T is the transmittance, and L is the average film thickness (μm))
The solar cell, wherein the antireflection film is made of a mixed crystal of silicon nitride and silicon oxide.

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