JP2014107504A - Photovoltaic device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photovoltaic device capable of providing brighter color.SOLUTION: In a photovoltaic device, a photovoltaic power element 70 has a receiving surface 70a. A protection substrate 40 is formed over the receiving surface 70a and has a main plane 40a opposing to the receiving surface 70a. A substrate-side color control layer 42 is formed over the main plane 40a between the receiving surface 70a and the main plane 40a, and the substrate-side color control layer 42 relatively strongly reflects a light of a part of wavelength included in the light transmitting the protection substrate 40. An element-side color control layer 22 is formed over the receiving surface 70a between the receiving surface 70a and the main plane 40a, and the element-side color control layer 22 relatively strongly reflects a light of a part of wavelength included in the light transmitting the substrate-side color control layer 42. A protective layer 44 fills an area between the substrate-side color control layer 42 and the element-side color control layer 22.

Description

  The present invention relates to a photovoltaic device.

  Photovoltaic elements, also called solar cells, that convert inexhaustible solar energy into electrical energy have been vigorously developed in various fields. For example, research and practical application of photovoltaic elements or photovoltaic devices using crystalline silicon such as single crystal silicon and polycrystalline silicon have been actively conducted.

  In recent years, since photovoltaic cells are used as power sources for buildings and houses, photovoltaic devices have been installed on roofs and walls. In this case, not only functions as power generation facilities are required, but buildings From the standpoint of aesthetic appearance, design functions may be required. For example, since most of photovoltaic elements using silicon are dark blue or black, attempts have been made to increase color variations by providing a color adjustment layer on the photovoltaic elements (patents) Reference 1).

JP 2010-45368 A

  Photovoltaic devices installed on roofs and walls generally include a transparent protective substrate for protecting the photovoltaic element, but the photovoltaic element provided with a color adjustment layer is covered with a transparent protective substrate. If this happens, the surface of the photovoltaic element will appear dark. Then, even if a vivid color is realized by the color adjustment layer in the state without the protective substrate, the color becomes dull when the protective substrate is provided, and the precious color is not utilized.

  This invention is made | formed in view of such a condition, The objective is to provide the photovoltaic apparatus which exhibits a brighter color.

  In order to solve the above problems, a photovoltaic device according to an aspect of the present invention includes a photovoltaic element having a light receiving surface, a protective substrate provided on the light receiving surface and having a main surface facing the light receiving surface. The light of a part of the wavelength included in the light that is provided between the light receiving surface and the main surface and is transmitted through the protective substrate is reflected relatively strongly compared to the light of other wavelengths. The substrate-side color control layer is provided between the light-receiving surface and the main surface, and is provided on the light-receiving surface. An element-side color control layer that reflects relatively strongly compared to light, and a protective layer that fills a space between the substrate-side color control layer and the element-side color control layer.

  ADVANTAGE OF THE INVENTION According to this invention, the brightness of the color which a photovoltaic apparatus exhibits can be improved.

It is sectional drawing which shows the structure of the photovoltaic apparatus which concerns on 1st Embodiment. It is a figure which shows the base substrate in which the texture structure was formed. It is a figure which shows the electric power generation layer in which the i-type layer and the conductivity type layer were formed. It is a figure which shows the photovoltaic element in which the electrode was formed. It is a figure which shows the photovoltaic element in which the element side color control layer was formed. It is a figure which shows the protective substrate in which the 2nd uneven structure was formed. It is a figure which shows the protective substrate in which the board | substrate side color control layer was formed. It is a figure which shows a mode that a photovoltaic element, a protective substrate, and a back sheet | seat are adhere | attached. It is a figure which shows typically the effect of the brightness improvement by two color control layers. It is a figure which shows typically the effect of the brightness improvement by two color control layers. It is a figure which shows the model which concerns on the comparative example 1 used for the wave optical simulation. It is a figure which shows the model which concerns on the comparative example 2 used for the wave optical simulation. It is a figure which shows the model which concerns on Example 1 used for the wave optical simulation. It is sectional drawing which shows the structure of the photovoltaic apparatus which concerns on 2nd Embodiment. It is a figure which shows the protective substrate which concerns on 2nd Embodiment. It is a figure which shows the protective substrate in which the board | substrate side color control layer was formed. It is a figure which shows a mode that a photovoltaic element, a protective substrate, and a back sheet | seat are adhere | attached. It is a figure which shows the model which concerns on Example 2 used for the wave optical simulation. It is sectional drawing which shows the structure of the photovoltaic apparatus which concerns on 3rd Embodiment. It is a figure which shows the base substrate which concerns on 3rd Embodiment. It is a figure which shows the photovoltaic element in which the i-type layer, the conductivity type layer, and the electrode were formed. It is a figure which shows the photovoltaic element in which the element side color control layer was formed. It is a figure which shows a mode that a photovoltaic element, a protective substrate, and a back sheet | seat are adhere | attached. It is a figure which shows the model which concerns on the comparative example 3 used for the wave optical simulation. It is a figure which shows the model which concerns on Example 3 used for the wave optical simulation.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate.

<First Embodiment>
FIG. 1 is a cross-sectional view showing the structure of the photovoltaic device 100 according to the first embodiment. In the photovoltaic device 100 according to the present embodiment, the element-side color control layer 22 formed on the light receiving surface 70a of the photovoltaic element 70 and the main surface of the protective substrate 40 (the light receiving surface 70a of the photovoltaic element 70). The substrate-side color control layer 42 is formed on the surface 40a, and a protective layer 44 is provided so that the two color control layers are spaced apart from each other. The two color control layers are formed of a multilayer film in which a plurality of control films having different refractive indexes are stacked, and relatively strongly reflect light having some wavelengths out of light incident on the color control layer. The photovoltaic device 100 makes the color of the photovoltaic device 100 visible from the protective substrate 40 side brighter by two color control layers provided at a predetermined interval.

  Although not particularly shown, the photovoltaic device 100 includes a plurality of photovoltaic elements 70. The photovoltaic element 70 includes a power generation layer 10, a first transparent electrode layer 18, a first metal electrode 20, a second transparent electrode layer 28, and a second metal electrode 30. The power generation layer 10 includes a base substrate 12, a first i-type layer 14, a first conductivity type layer 16, a second i-type layer 24, and a second conductivity type layer 26.

The base substrate 12 is a crystalline semiconductor layer, for example, a single crystal semiconductor layer or a polycrystalline semiconductor layer in which a large number of crystal grains are aggregated. Here, an n-type crystalline silicon substrate to which an n-type dopant is added is used as the base substrate 12, and the doping concentration is about 10 ¹⁶ / cm ³ . Further, the base substrate 12 is provided with a texture structure 62 for improving the efficiency of absorbing light incident on the photovoltaic element 70. By providing the texture structure 62, the traveling direction of the light incident on the photovoltaic element 70 can be changed, and the optical path length of the light incident on the base substrate 12 can be increased. The texture structure 62 is also used to form a first concavo-convex structure 64 reflected in the element-side color control layer 22 described later.

The first i-type layer 14 and the first conductivity type layer 16 are amorphous semiconductor layers, and are semiconductor layers including an amorphous phase or a microcrystalline phase in which minute crystal grains are precipitated in the amorphous phase. is there. Here, amorphous silicon containing hydrogen is used. The first i-type layer 14 is substantially intrinsic amorphous silicon, and the first conductivity type layer 16 is amorphous silicon to which a p-type dopant is added. The first conductivity type layer 16 is made of silicon having a dopant concentration higher than that of the first i-type layer 14. For example, the first i-type layer 14 is not intentionally doped, and the dopant concentration of the first conductivity type layer 16 may be about 10 ¹⁸ / cm ³ .

  The thickness of the first i-type layer 14 is desirably as thin as possible in order to suppress light absorption as much as possible, and is preferably set to such an extent that the surface of the base substrate 12 is sufficiently passivated. Specifically, the thickness of the first i-type layer 14 may be 1 nm or more and 50 nm or less, for example, 10 nm.

  The first conductivity type layer 16 is preferably as thin as possible in order to suppress light absorption as much as possible, and is preferably thick enough to increase the open circuit voltage of the photovoltaic element 70 sufficiently. Specifically, the thickness of the first conductivity type layer 16 may be, for example, not less than 1 nm and not more than 50 nm, for example, 10 nm.

The second i-type layer 24 and the second conductivity type layer 26 are amorphous semiconductor layers, and are semiconductor layers including an amorphous phase or a microcrystalline phase in which minute crystal grains are precipitated in the amorphous phase. Yes, here it is assumed to be amorphous silicon containing hydrogen. The second i-type layer 24 is substantially intrinsic amorphous silicon, and the second conductivity type layer 26 is amorphous silicon to which an n-type dopant is added. The second conductivity type layer 26 is a silicon layer having a dopant concentration higher than that of the second i-type layer 24. For example, the first conductivity type layer 16 is not intentionally doped, and the dopant concentration of the second conductivity type layer 26 may be about 10 ¹⁸ / cm ³ .

  The thickness of the second i-type layer 24 is preferably thick enough that the surface of the base substrate 12 is sufficiently passivated. Specifically, the thickness of the second i-type layer 24 may be 1 nm or more, for example, 10 nm. Further, the thickness of the second conductivity type layer 26 is preferably set such that the open circuit voltage of the photovoltaic element 70 becomes sufficiently high. The thickness of the second conductivity type layer 26 may be 1 nm or more, for example, 200 nm.

The first transparent electrode layer 18 and the second transparent electrode layer 28 are made of tin oxide (SnO ₂ ), zinc oxide (ZnO), indium tin oxide (ITO), etc., tin (Sn), antimony (Sb), fluorine (F ), Transparent conductive oxide (TCO) doped with aluminum (Al) or the like, it is preferable to use at least one kind or a combination of plural kinds. In particular, zinc oxide (ZnO) has advantages such as high translucency and low resistivity. The film thicknesses of the first transparent electrode layer 18 and the second transparent electrode layer 28 may be 10 nm or more and 500 nm or less, for example, 100 nm.

  The first metal electrode 20 and the second metal electrode 30 are provided on the light receiving surface 70a of the photovoltaic element 70 and the back surface facing the light receiving surface 70a, respectively, and are electrodes for taking out the electric power generated by the power generation layer 10 to the outside. It is. The first metal electrode 20 and the second metal electrode 30 are conductive materials including, for example, copper (Cu) or aluminum (Al). An electrolytic plating layer such as copper (Cu) or tin (Sn) may be included. However, it is not limited to this, It is good also as other metals, such as gold | metal | money and silver, another electroconductive material, or those combinations.

  In the present embodiment, the first transparent electrode layer 18 side of the photovoltaic element 70 is the light receiving surface 70a. Here, the light receiving surface means a main surface on which light (sunlight) A is mainly incident on the photovoltaic element 70, and specifically, a large amount of light A incident on the photovoltaic element 70. This is the surface on which the part is incident.

  In addition, the photovoltaic device 100 includes an element side color control layer 22, a substrate side color control layer 42, a protective substrate 40, a back sheet 50, and a protective layer 44.

  The element-side color control layer 22 is formed on the light-receiving surface 70a of the photovoltaic element 70, and relatively strongly reflects light having some wavelengths out of light incident on the light-receiving surface 70a from the protective substrate 40 side. Accordingly, the color control layer presents a predetermined color. The element-side color control layer 22 is configured by a multilayer film in which a plurality of control films having different refractive indexes are stacked. For example, the element-side color control layer 22 is a dielectric multilayer film in which a plurality of types of dielectrics are stacked in layers. Specifically, a silicon oxide (SiO) layer having a refractive index of about 4.0, a silicon nitride (SiN) layer having a refractive index of about 2.0, or the like is used. It is desirable to appropriately select the refractive index and film thickness of each control film constituting the multilayer film according to the required color. The element side color control layer 22 has a first uneven structure 64 reflecting the texture structure 62 of the base substrate 12.

  The protective substrate 40 protects the photovoltaic element 70 from the external environment and transmits light in a wavelength band that the photovoltaic element 70 absorbs for power generation. The protective substrate 40 is, for example, a glass substrate.

  The protective substrate 40 is opposed to the light receiving surface 70a of the photovoltaic element 70, has a main surface 40a to which the substrate-side color control layer 42 is bonded, and the second concavo-convex structure 66 is provided on the main surface 40a.

  The substrate-side color control layer 42 is formed on the main surface 40a of the protective substrate 40, and relatively strongly reflects light having some wavelengths out of light incident on the main surface 40a from the protective substrate 40 side. The color control layer presents a predetermined color. Similar to the element-side color control layer 22, the substrate-side color control layer 42 is configured by a multilayer film in which a plurality of control films having different refractive indexes are stacked, and the refractive index and film thickness of each control film constituting the multilayer film. Is preferably selected according to the required color. The substrate-side color control layer 42 has a concavo-convex structure that reflects the shape of the second concavo-convex structure 66 formed on the protective substrate 40.

  The protective layer 44 and the back sheet 50 are resin materials such as EVA and polyimide. Thereby, while preventing the penetration | invasion of the water | moisture content to the electric power generation layer of the photovoltaic apparatus 100, the intensity | strength of the photovoltaic apparatus 100 whole is improved. The protective layer 44 plays a role of filling a space between the element-side color control layer 22 and the substrate-side color control layer 42 so that a predetermined distance is provided. The back sheet 50 may be the same glass as the protective substrate 40 or a transparent substrate such as plastic. Further, by providing a reflective layer between the protective layer 44 and the back sheet 50 so that a large amount of light incident from the protective substrate 40 side is absorbed by the power generation layer 10, the back sheet is transmitted through the photovoltaic element 70. The light reaching 50 may be reflected to the photovoltaic element 70.

Next, a method for manufacturing the photovoltaic device 100 will be described.
FIG. 2 is a diagram illustrating the base substrate 12 on which the texture structure 62 is formed. The base substrate 12 is a crystalline semiconductor material, for example, a semiconductor substrate such as silicon, polycrystalline silicon, gallium arsenide (GaAs), or indium phosphide (InP). Note that in this embodiment, an example in which a single crystal silicon substrate is used as the base substrate 12 is described. Therefore, the first i-type layer 14, the first conductivity type layer 16, the second i-type layer 24, and the second conductivity type layer 26 described later are also silicon layers. However, the base substrate 12 may be made of a material other than silicon, and these layers may be made of materials other than the silicon layer.

  In FIG. 2, a texture structure 62 is formed on the first surface 12 a and the second surface 12 b of the base substrate 12. By chemically etching the base substrate 12 in a sodium hydroxide (NaOH) aqueous solution, a texture structure 62 having a fine uneven shape is formed on the surface of the base substrate 12. It is desirable to control the concavo-convex shape of the texture structure 62 by changing the concentration of NaOH aqueous solution used for etching, reaction time, or the like.

  FIG. 3 is a diagram showing the power generation layer 10 in which the i-type layer and the conductivity type layer are formed. A first i-type layer 14 and a first conductivity type layer 16 are sequentially formed on the first surface 12a of the base substrate 12, and a second i-type layer 24 and a second conductivity type layer 26 are formed on the second surface 12b. The power generation layer 10 is formed by sequentially forming the layers.

The first i-type layer 14 and the first conductivity type layer 16 can be formed by plasma enhanced chemical vapor deposition (PECVD) using a silicon-containing gas such as silane (SiH ₄ ). While supplying a silicon-containing gas such as silane (SiH ₄ ) and supplying high-frequency power from a high-frequency power source to a high-frequency electrode, a raw material gas plasma is generated, and the raw material is supplied from the plasma onto the base substrate 12 to form a silicon thin film. Is formed. The source gas is mixed with a dopant-containing gas such as diborane (B ₂ H ₆ ) as necessary.

Similarly, the second i-type layer 24 and the second conductivity-type layer 26 can also be formed by plasma enhanced chemical vapor deposition (PECVD) using a silicon-containing gas such as silane (SiH ₄ ). The source gas is mixed with a dopant-containing gas such as phosphine (PH ₃ ) as necessary.

  FIG. 4 is a diagram showing a photovoltaic element 70 on which an electrode is formed. The first transparent electrode layer 18 and the first metal electrode 20 are formed on the first conductivity type layer 16, and the second transparent electrode layer 28 and the second metal electrode 30 are formed on the second conductivity type layer 26. .

  The first transparent electrode layer 18 and the second transparent electrode layer 28 can be formed by a thin film forming method such as sputtering or plasma enhanced chemical vapor deposition (PECVD). The first metal electrode 20 and the second metal electrode 30 can be formed by printing a conductive material such as silver (Ag) paste by a screen printing method.

FIG. 5 is a diagram showing the photovoltaic element 70 on which the element-side color control layer 22 is formed. The element side color control layer 22 is formed on the first transparent electrode layer 18 and the first metal electrode 20 which are the light receiving surface 70a. The element-side color control layer 22 may be formed by plasma enhanced chemical vapor deposition (PECVD) in which a source gas in which oxygen (O ₂ ) or nitrogen (N ₂ ) is mixed with silane (SiH ₄ ) is supplied as a plasma. it can. Thereby, the element-side color control layer 22 has a first uneven structure 64 reflecting the texture structure 62 formed on the base substrate 12.

  FIG. 6 is a diagram showing the protective substrate 40 on which the second concavo-convex structure 66 is formed. In the protective substrate 40, a second concavo-convex structure 66 having a fine concavo-convex shape is formed on the main surface 40a on which the substrate-side color control layer 42 is formed. The second concavo-convex structure 66 can be formed by blasting or the like in which fine particles collide with the main surface 40a.

FIG. 7 is a view showing the protective substrate 40 on which the substrate-side color control layer 42 is formed. The substrate side color control layer 42 is formed on the main surface 40a on which the second uneven structure 66 is formed. Similar to the element-side color control layer 22, the substrate-side color control layer 42 is formed by plasma chemical vapor deposition in which a source gas in which oxygen (O ₂ ) or nitrogen (N ₂ ) is mixed with silane (SiH ₄ ) is converted into plasma and supplied. It can be formed by the method (PECVD). Thereby, the substrate side color control layer 42 has a concavo-convex structure reflecting the second concavo-convex structure 66 formed on the main surface 40a.

  FIG. 8 is a diagram illustrating a state in which the photovoltaic element 70, the protective substrate 40, and the back sheet 50 are bonded. A first protective film 44a serving as a protective layer 44 is sandwiched between the element-side color control layer 22 of the photovoltaic element 70 shown in FIG. 5 and the substrate-side color control layer 42 shown in FIG. And the 2nd protective film 44b used as the protective layer 44 is inserted | pinched between the 2nd metal electrode 30 and the back sheet | seat 50. FIG. The first protective film 44a and the second protective film 44b are sheets made of a resin such as EVA or polyimide. By thermocompression bonding with the photovoltaic element 70 sandwiched between the protective substrate 40 and the backsheet 50, the first protective film 44a and the second protective film 44b are fused to form the protective layer 44, and the light shown in FIG. The electromotive force device 100 is formed.

  With the manufacturing method described above, the photovoltaic device 100 is provided with the element-side color control layer 22 on the light-receiving surface 70a of the photovoltaic element 70, and on the main surface 40a of the protective substrate 40 facing the light-receiving surface 70a. The side color control layer 42 is provided, and the protective layer 44 provides a predetermined interval therebetween.

  9 and 10 are diagrams schematically showing the effect of improving the brightness by the two color control layers. 9 shows a case where the substrate-side color control layer 42 is not provided as Comparative Example 1, and FIG. 10 shows a case where two color control layers are provided as this embodiment. In FIG. 10, the first transparent electrode layer 18 and the first metal electrode 20 included in the photovoltaic element 70 are omitted, and the element-side color control layer 22 having the first uneven structure 64 on the power generation layer 10 is provided. The state where it is formed is shown.

As shown in FIG. 9, the incident light A incident on the upper surface 40 b of the protective substrate 40 passes through the protective substrate 40 and the protective layer 44 and reaches the element-side color control layer 22. Some wavelengths of light are reflected as reflected light B toward the protective substrate 40, and other wavelengths of light are absorbed by the power generation layer 10 and contribute to power generation. At this time, the reflected light B reflected by the element-side color control layer 22, if the incident angle theta ₁ to the upper surface 40b of the protective substrate 40 is less than the critical angle, even when observing from an oblique, the user's eye E Although so that the reach, the incident angle theta ₁ to the upper surface 40b is equal to or greater than the critical angle, resulting in total reflection at the top surface 40b. Then, the total reflected light C is confined inside the photovoltaic device 100 and cannot reach the user's eyes E. As a result, the color presented by the element-side color control layer 22 looks dark, and bright and vivid colors are not presented.

  On the other hand, in the case of the photovoltaic device 100 shown in FIG. 10, incident light A <b> 1 incident on the upper surface 40 b of the protective substrate 40 is light having a part of the wavelength by the substrate-side color control layer 42 having the second concavo-convex structure 66. Is reflected as reflected light B1, and light of other wavelengths passes through the substrate-side color control layer 42 as transmitted light A2 and reaches the element-side color control layer 22. The transmitted light A2 is reflected by the element-side color control layer 22 having the first concavo-convex structure 64 so that a part of the light is reflected as the reflected light B2 toward the protective substrate 40, and the other light is generated by the power generation layer 10. It is absorbed by and contributes to power generation.

At this time, the reflected light B2 reflected by the element-side color control layer 22 is scattered by the second uneven structure 66 when passing through the substrate-side color control layer 42, so that the reflected light B2 is applied to the upper surface 40b of the protective substrate 40. the incident angle theta ₂ is changed as compared with the case where there is no substrate-side color control layer 42. For example, some of the light that would be incident on the upper surface 40b at an angle greater than the critical angle when there is no substrate-side color control layer 42 is scattered by the substrate-side color control layer 42, the incident angle theta ₂ is less than the critical angle And reaches the user's eyes E as scattered light B3. As a result, it is possible to make the color presented by the element-side color control layer 22 appear brighter than when the substrate-side color control layer 42 is not provided.

  Further, the photovoltaic device 100 includes the substrate-side color control layer 42, so that the reflected light B1 reflected by the substrate-side color control layer 42 reaches the user's eyes. Therefore, the color presented by the substrate-side color control layer 42 is visible to the user, and a brighter color can be presented as compared with the case where the substrate-side color control layer 42 shown in FIG. 9 is not provided. .

  The effect of brightness improvement by the above two color control layers was obtained by wave optics simulation. In the simulation, the intensity of visible light contained in the reflected light B was obtained with respect to the incident light A incident on the photovoltaic device. Further, when the brightness of the reflected light reflected from the photovoltaic device is increased, the ratio of the light absorbed by the photovoltaic element is expected to decrease and the power generation efficiency is expected to decrease. The value of the power generation amount was obtained from the intensity of the absorbed light, and the extent to which the power generation amount decreased with respect to the brightness of the reflected light B was calculated.

  11 to 13 show models used for wave optical simulation. FIG. 11 shows a model according to Comparative Example 1 used in the wave optical simulation. In Comparative Example 1, a silicon substrate layer having a thickness of 50 μm provided with a texture structure with a period of 1 μm is set as the power generation layer 10, and the element side color control layer 22 is formed thereon with a thickness of 280 nm and a refractive index of 2.0. A first control film 22a and a second control film 22b having a thickness of 5 nm and a refractive index of 4.0 were set. Further, a medium having a thickness of 50 μm and a refractive index of 1.5 was set as the protective substrate 40.

  FIG. 12 shows a model according to Comparative Example 2 used in the wave optical simulation. In Comparative Example 2, as in Comparative Example 1 shown in FIG. 11, a 50 μm thick silicon substrate layer having a texture structure with a period of 1 μm is set as the power generation layer 10, and the element side color control layer 22 is formed thereon. A first control film 22a having a thickness of 280 nm and a refractive index of 2.0 and a second control film 22b having a thickness of 5 nm and a refractive index of 4.0 were set. In Comparative Example 2, the protective layer 44 is not provided, and the substrate-side color control layer 42 is formed immediately above the element-side color control layer 22 as a third control film 42b having a thickness of 5 nm and a refractive index of 4.0. A fourth control film 42a having a thickness of 280 nm and a refractive index of 2.0 was set.

  FIG. 13 shows a model according to Example 1 used for the wave optical simulation. Note that Example 1 corresponds to the first embodiment. In Example 1, a medium having a thickness of 2 μm and a refractive index of 1.5 was set as the protective layer 44 between the element side color control layer 22 and the substrate side color control layer 42 shown in FIG. The period of the concavo-convex structure of the substrate-side color control layer 42 was set to 0.25 μm, which is different from that of the element-side color control layer 22.

  As a result of the simulation using the above model, the brightness of the visible light included in the reflected light B was improved by about 70% in Example 1 compared to Comparative Example 1. Further, the reduction rate of the power generation amount with respect to the brightness of the reflected light B was 13.2% in the comparative example 1, while the result of 9.5% was obtained in the example 1. On the other hand, in the comparative example 2 in which the protective layer 44 is not provided with respect to the comparative example 1, the brightness of the visible light included in the reflected light B is improved only by about 5%, and the amount of power generation relative to the brightness of the reflected light B is increased. The reduction rate was 11.7%. Therefore, it was found that providing two color control layers with a predetermined interval can improve the brightness of reflected light and suppress the decrease in power generation efficiency with respect to the brightness of reflected light.

<Second Embodiment>
FIG. 14 is a cross-sectional view showing the structure of the photovoltaic device 200 according to the second embodiment. Hereinafter, the difference from the photovoltaic device 100 in the first embodiment will be mainly described. The photovoltaic device 200 includes an element-side color control layer 22 formed on the light-receiving surface 70a of the photovoltaic element 70, and a substrate-side color control layer 42 formed on the main surface 40a of the protective substrate 40. In addition, the protective layer 44 is provided so that these two color control layers have a predetermined interval. The photovoltaic device 200 has the first feature that the main surface 40a of the protective substrate 40 is not provided with an uneven structure, and the substrate-side color control layer 42 formed on the main surface 40a is also not provided with an uneven structure. Different from the photovoltaic device 100 in the embodiment.

Next, a method for manufacturing the photovoltaic device 200 will be described.
FIG. 15 is a diagram illustrating a protective substrate 40 according to the second embodiment. Unlike the first embodiment, the protective substrate 40 is not formed with an uneven shape on the main surface 40a on which the substrate-side color control layer 42 is formed, and the main surface 40a is flat.

FIG. 16 is a view showing the protective substrate 40 on which the substrate-side color control layer 42 is formed. The substrate side color control layer 42 is formed on the main surface 40a on which the second uneven structure 66 is formed. The substrate-side color control layer 42 may be formed by plasma enhanced chemical vapor deposition (PECVD) in which a source gas in which oxygen (O ₂ ) or nitrogen (N ₂ ) is mixed with silane (SiH ₄ ) is supplied as a plasma. it can.

  FIG. 17 is a diagram illustrating a state in which the photovoltaic element 70, the protective substrate 40, and the back sheet 50 are bonded. A first protective film 44a serving as a protective layer 44 is sandwiched between the element-side color control layer 22 of the photovoltaic element 70 shown in FIG. 5 and the substrate-side color control layer 42 shown in FIG. And the 2nd protective film 44b used as the protective layer 44 is inserted | pinched between the 2nd metal electrode 30 and the back sheet | seat 50. FIG. The first protective film 44a and the second protective film 44b are sheets made of a resin such as EVA or polyimide. When the photovoltaic element 70 is thermocompression bonded with the protective substrate 40 and the backsheet 50 sandwiched, the first protective film 44a and the second protective film 44b are fused to form the protective layer 44, and the light shown in FIG. An electromotive force device 200 is formed.

  FIG. 18 shows a model according to Example 2 used in the wave optics simulation. Example 2 corresponds to the second embodiment. In Example 2, similarly to Example 1 shown in FIG. 13, a 50 μm-thick silicon substrate layer having a texture structure with a period of 1 μm is set as the power generation layer 10, and the element-side color control layer 22 is formed thereon. A first control film 22a having a thickness of 280 nm and a refractive index of 2.0 and a second control film 22b having a thickness of 5 nm and a refractive index of 4.0 were set. Further, a medium having a thickness of 2 μm and a refractive index of 1.5 is set as the protective layer 44, and a flat substrate-side color control layer having no uneven structure thereon is formed with a thickness of 280 nm and a refractive index of 2.0. A third control film 42a and a fourth control film 42b having a thickness of 5 nm and a refractive index of 4.0 were set.

  As a result of the simulation by the above model, the brightness of the visible light included in the reflected light B can be improved three times or more in the second embodiment compared to the first comparative example shown in FIG. Moreover, about the reduction | decrease rate of the electric power generation amount with respect to the brightness of the reflected light B, the result of 7.8% was obtained. Therefore, even if two color control layers are provided at a predetermined interval and the substrate-side color control layer 42 has a flat structure, the brightness of the reflected light is improved and the power generation efficiency with respect to the brightness of the reflected light is reduced. I found that it can be suppressed.

<Third Embodiment>
FIG. 19 is a cross-sectional view showing the structure of the photovoltaic device 300 according to the third embodiment. Hereinafter, the difference from the photovoltaic device 100 in the first embodiment will be mainly described. The photovoltaic device 300 includes an element side color control layer 22 formed on the light receiving surface 70 a of the photovoltaic element 70 and a substrate side color control layer 42 formed on the main surface 40 a of the protective substrate 40. In addition, the protective layer 44 is provided so that these two color control layers have a predetermined interval. In the photovoltaic device 300, the light receiving surface 70a of the photovoltaic element 70 is not provided with an uneven structure, and the element side color control layer 22 formed on the light receiving surface 70a is also not provided with an uneven structure. It differs from the photovoltaic device 100 in one embodiment.

Next, a method for manufacturing the photovoltaic device 300 will be described.
FIG. 20 is a diagram illustrating the base substrate 12 according to the third embodiment. The base substrate 12 is a single crystal silicon substrate as in the first embodiment. However, unlike the first embodiment, a texture structure is not provided on the surface.

FIG. 21 is a diagram showing a photovoltaic element 70 in which an i-type layer, a conductive type layer, and an electrode are formed. The first i-type layer 14 and the first conductivity type layer 16 can be formed by plasma enhanced chemical vapor deposition (PECVD) using a silicon-containing gas such as silane (SiH ₄ ). The source gas is mixed with a dopant-containing gas such as diborane (B ₂ H ₆ ) as necessary. Similarly, the second i-type layer 24 and the second conductivity-type layer 26 can also be formed by plasma enhanced chemical vapor deposition (PECVD) using a silicon-containing gas such as silane (SiH ₄ ). The source gas is mixed with a dopant-containing gas such as phosphine (PH ₃ ) as necessary.

  The first transparent electrode layer 18 and the first metal electrode 20 are formed on the first conductivity type layer 16, and the second transparent electrode layer 28 and the second metal electrode 30 are formed on the second conductivity type layer 26. . The first transparent electrode layer 18 and the second transparent electrode layer 28 can be formed by a thin film forming method such as sputtering or plasma enhanced chemical vapor deposition (PECVD). The first metal electrode 20 and the second metal electrode 30 can be formed by printing a conductive material such as silver (Ag) paste by a screen printing method.

FIG. 22 shows a photovoltaic element 70 on which the element-side color control layer 22 is formed. The element side color control layer 22 is formed on the first transparent electrode layer 18 and the first metal electrode 20 which are the light receiving surface 70a. The element-side color control layer 22 may be formed by plasma enhanced chemical vapor deposition (PECVD) in which a source gas in which oxygen (O ₂ ) or nitrogen (N ₂ ) is mixed with silane (SiH ₄ ) is supplied as a plasma. it can.

  FIG. 23 is a diagram illustrating a state in which the photovoltaic element 70, the protective substrate 40, and the back sheet 50 are bonded. A first protective film 44a serving as a protective layer 44 is sandwiched between the element-side color control layer 22 of the photovoltaic element 70 shown in FIG. 22 and the substrate-side color control layer 42 shown in FIG. And the 2nd protective film 44b used as the protective layer 44 is inserted | pinched between the 2nd metal electrode 30 and the back sheet | seat 50. FIG. The first protective film 44a and the second protective film 44b are sheets made of a resin such as EVA or polyimide. By thermocompression bonding with the photovoltaic element 70 sandwiched between the protective substrate 40 and the backsheet 50, the first protective film 44a and the second protective film 44b are fused to form the protective layer 44, and the light shown in FIG. An electromotive force device 300 is formed.

  24 and 25 show models according to Comparative Example 3 and Example 3 used in the wave optical simulation. FIG. 24 shows a model according to Comparative Example 3 used in the wave optical simulation. In Comparative Example 3, unlike Comparative Example 1, no texture structure is provided on the surface of the power generation layer 10, and no uneven structure is provided on the element-side color control layer 22 formed thereon. Note that, except that the uneven structure is not provided, it is the same as Comparative Example 1, and the thickness and refractive index of each layer are the same as Comparative Example 1.

  FIG. 25 shows a model according to Example 3 used for the wave optical simulation. Example 3 corresponds to the third embodiment. In Example 3, a medium having a thickness of 2 μm and a refractive index of 1.5 is set as a protective layer 44 on the flat element-side color control layer 22 shown in FIG. As the control layer 42, a third control film 42a having a thickness of 280 nm and a refractive index of 2.0 and a fourth control film 42b having a thickness of 5 nm and a refractive index of 4.0 were set. The irregularity period of the substrate side color control layer 42 was 0.25 μm.

  As a result of the simulation using the above model, the brightness of the visible light included in the reflected light B was improved by about 15% in Example 3 as compared to Comparative Example 3. The reduction rate of the amount of power generation with respect to the brightness of the reflected light B was 4.7% in Comparative Example 3, whereas it was 4.6% in Example 3. Therefore, even if two color control layers are provided at a predetermined interval and the element-side color control layer 22 has a flat structure, the brightness of the reflected light is improved and the power generation efficiency with respect to the brightness of the reflected light is reduced. I found that it can be suppressed.

  As described above, the present invention has been described with reference to the above-described embodiments. However, the present invention is not limited to the above-described embodiments, and the configurations of the embodiments are appropriately combined or replaced. Those are also included in the present invention. Further, it is possible to appropriately change the combination and processing order in each embodiment based on the knowledge of those skilled in the art and to add various modifications such as various design changes to each embodiment. Embodiments to which is added can also be included in the scope of the present invention.

  In each embodiment, the structure in which the first metal electrode 20 is buried in the element-side color control layer 22 is shown. However, by making the first metal electrode 20 higher than the thickness of the element-side color control layer 22, You may make it protrude from the side color control layer 22. FIG. By projecting the first metal electrode 20, it is possible to easily extract electric power from the first metal electrode 20 when the element-side color control layer 22 does not have conductivity. Further, the element-side color control layer 22 may have the function of the first transparent electrode layer 18 by being composed of a conductive control film.

  In addition, the photovoltaic device by the following combinations can also be included in the scope of the present invention.

  (1) A photovoltaic device includes a photovoltaic element having a light receiving surface, a protective substrate provided on the light receiving surface and having a main surface facing the light receiving surface, and between the light receiving surface and the main surface. A substrate-side color control layer that is provided on the main surface and reflects light of a part of wavelengths included in the light transmitted through the protective substrate relatively strongly as compared with light of other wavelengths; and a light receiving surface; Provided on the light receiving surface between the main surfaces, and reflects light of some wavelengths included in the light transmitted through the substrate-side color control layer relatively strongly as compared with light of other wavelengths. An element-side color control layer; and a protective layer filling a space between the substrate-side color control layer and the element-side color control layer.

  According to this aspect, it is possible to cause the photovoltaic device to exhibit a predetermined color by the light that is relatively strongly reflected by the element side color control layer and the substrate side color control layer that are spaced apart by the protective layer. it can. Further, by providing two color control layers, the intensity of light reflected by each color control layer and emitted from the protective substrate can be increased, and a brighter color can be presented.

  (2) The photovoltaic device according to (1), wherein a concavo-convex structure is provided on at least one of the light receiving surface and the main surface. By providing the concavo-convex structure, a more uniform color can be presented even when the angle of viewing by the user with respect to the protective substrate 40 changes.

  (3) The photovoltaic device according to (2), wherein the light-receiving surface is provided with a first uneven structure, and the main surface is provided with a second uneven structure having a period different from that of the first uneven structure. It may be.

  (4) The photovoltaic device according to any one of (1) to (3), wherein at least one of the substrate-side color control layer and the element-side color control layer includes a plurality of control films having different refractive indexes. It may be.

  DESCRIPTION OF SYMBOLS 10 ... Electric power generation layer, 18 ... 1st transparent electrode layer, 20 ... 1st metal electrode, 22 ... Element side color control layer, 28 ... 2nd transparent electrode layer, 30 ... 2nd metal electrode, 40 ... Protection board, 40a ... Main surface, 42... Substrate-side color control layer, 44... Protective layer, 50 .. backsheet, 62 .. texture structure, 64 .. first concavo-convex structure, 66 ... second concavo-convex structure, 70. ... light-receiving surface, 100, 200, 300 ... photovoltaic device.

Claims (4)

A photovoltaic element having a light receiving surface;
A protective substrate provided on the light receiving surface and having a main surface facing the light receiving surface;
A part of the wavelength of light included in the light that is provided between the light receiving surface and the main surface and is transmitted on the main surface and transmitted through the protective substrate is relatively compared with light of other wavelengths. A substrate-side color control layer that strongly reflects;
Compared with light of other wavelengths, the light of some wavelengths included in the light that is provided between the light receiving surface and the main surface and is transmitted on the light receiving surface and transmitted through the substrate-side color control layer An element-side color control layer that reflects relatively strongly;
A protective layer filling the space between the substrate side color control layer and the element side color control layer;
A photovoltaic device comprising:   The photovoltaic device according to claim 1, wherein an uneven structure is provided on at least one of the light receiving surface and the main surface.   3. The light-receiving surface is provided with a first uneven structure, and the main surface is provided with a second uneven structure having a period different from that of the first uneven structure. Photovoltaic device.   4. The photovoltaic device according to claim 1, wherein at least one of the substrate-side color control layer and the element-side color control layer includes a plurality of control films having different refractive indexes. .

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