Color adjustment plate and solar cell module

Abstract

To provide a color adjustment plate with low angle dependence.SOLUTION: A color adjustment plate 10 of the present invention comprises a substrate 1, and a dielectric multilayer 2 that is formed on the substrate 1 and has high refractive index layers and low refractive index layers alternately laminated with each other. The dielectric multilayer 2 is configured to satisfy the following (1-1) to (1-3). (1-1) White light made incident from the vertical direction and reflected in the same direction as the vertical direction indicates spectral reflection characteristics having a plurality of reflection peaks within a wavelength range of 380 nm or more and 780 nm or less. (1-2) The plurality of reflection peaks include at least one first main reflection peak with a wavelength less than 520 nm and one second main reflection peak with a wavelength of 520 nm or more. (1-3) The plurality of reflection peaks indicate a reflectance of 20% or more relative to the reflection peak indicating the maximum reflectance among the reflection peaks within the wavelength range.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] This invention relates to a color adjustment plate, a solar cell module, a method for manufacturing a color adjustment plate, a film deposition method, and a film deposition apparatus. [Background technology]

[0002] When installing solar modules on a building, they are sometimes installed not only on the roof but also on walls and other surfaces to increase power generation. In this case, the surface of the solar modules is usually black, which poses an aesthetic problem.

[0003] It has been proposed to color the appearance of a solar cell module by forming a colored coating layer on a glass substrate placed on the light-receiving side of the solar cell module (see Patent Document 1). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] International Publication No. 2017 / 090056 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, coloring the exterior of solar cell modules presents a problem: the light reflected by the color is reduced, preventing some light from reaching the modules and thus lowering their conversion efficiency. Therefore, there is a need for coloring technologies that can suppress this decrease in conversion efficiency.

[0006] As a result of intensive studies, the inventor of the present invention has developed a coloring technique capable of suppressing a decrease in conversion efficiency. Further, in examining such a coloring technique, the inventor faced a problem that even when reflected light of a desired color was obtained by specular reflection, the color of the reflected light changed when the incident angle changed. Therefore, as a result of further studies, a method for reducing the incident angle dependence of the reflected light was found. Furthermore, having conceived that the method is applicable not only to solar cell modules, the present invention with low incident angle dependence of reflected light has been completed.

[0007] The present invention has been made in view of the above circumstances, and an object thereof is to provide a color adjusting plate, a solar cell module, a method for manufacturing a color adjusting plate, a film forming method, and a film forming apparatus having low angle dependence.

Means for Solving the Problems

[0008] In order to solve the above problems, the present invention provides the following means.

[0009] Aspect 1 of the present invention is a color adjusting plate including a substrate and a dielectric multilayer film formed on the substrate and having a high refractive index layer and a low refractive index layer alternately laminated, wherein the dielectric multilayer film is configured to satisfy the following (1-1) to (1-3); (1-1) It exhibits a spectral reflection characteristic in which white light is incident from the vertical direction and the reflected light reflected in the same direction as the vertical direction has a plurality of reflection peaks in a wavelength range of 380 nm or more and 780 nm or less. (1-2) The plurality of reflection peaks each include at least one first main reflection peak having a wavelength of less than 520 nm and one second main reflection peak having a wavelength of 520 nm or more. (1-3) The plurality of reflection peaks exhibit a reflectance of 20% or more with respect to the reflection peak showing the maximum reflectance among the reflection peaks in the wavelength range.

[0010] Aspect 2 of the present invention is the color adjusting plate according to Aspect 1, wherein one of the film forming surface of the substrate on which the dielectric multilayer film is formed and the non-film forming surface on which the dielectric multilayer film is not formed is formed as a diffusion reflection surface having an uneven structure.

[0011] Aspect 3 of the present invention is a color adjustment plate in the color adjustment plate of Aspect 2, wherein the non-film-forming surface is formed as a diffuse reflection surface.

[0012] Aspect 4 of the present invention is a color adjustment plate in the color adjustment plate of Aspect 3, wherein the root mean square height Rq of the diffuse reflection surface is 0.4 μm to 1.3 μm.

[0013] Aspect 5 of the present invention is a color adjustment plate in any one of the color adjustment plates of Aspect 1 to Aspect 4, wherein the substrate is a diffusion plate.

[0014] Aspect 6 of the present invention is a color adjustment plate in any one of the color adjustment plates of Aspect 1 to Aspect 5, wherein the plurality of reflection peaks are two reflection peaks.

[0015] Aspect 7 of the present invention is a color adjustment plate in any one of the color adjustment plates of Aspect 1 to Aspect 5, wherein the plurality of reflection peaks are three reflection peaks.

[0016] Aspect 8 of the present invention is a color adjustment plate in any one of the color adjustment plates of Aspect 1 to Aspect 5, wherein the plurality of reflection peaks are four reflection peaks.

[0017] Aspect 9 of the present invention is a color adjustment plate in any one of the color adjustment plates of Aspect 1 to Aspect 8, wherein the dielectric multilayer film is further configured to satisfy the following (1-4); (1-4) When the incident angle from the vertical direction is changed from 0° to 30°, the changes in the x-coordinate and y-coordinate in the chromaticity coordinates (x, y) on the CIE-xy chromaticity diagram of the reflected light are both 0.1 or less.

[0018] Aspect 10 of the present invention is a color adjustment plate in any one of the color adjustment plates of Aspect 1 to Aspect 9, wherein the dielectric multilayer film is further configured to satisfy the following (1-5); (1-5) The full width at half maximum (FWHM) of at least one of the first main reflection peak and the second main reflection peak is 200 nm or less.

[0019] Aspect 11 of the present invention is a color adjustment plate in which, in any one of aspects 1 to 10, the dielectric multilayer film is further configured to satisfy the following (1-6); (1-6) The reflectance of both the first principal reflect peak and the second principal reflect peak is 70% or less.

[0020] Aspect 12 of the present invention is a color adjustment plate in which, in any one of aspects 1 to 11, the dielectric multilayer film is further configured to satisfy the following (1-7); (1-7) The chromaticity coordinates (x, y) on the CIE-xy chromaticity diagram of the reflected light lie within the range bounded by 0.25 ≤ x ≤ 0.4 and 0.25 ≤ y ≤ 0.4.

[0021] Aspect 13 of the present invention is a color adjustment plate in any one of aspects 1 to 12, wherein the dielectric multilayer film is further configured to satisfy the following (1-8); (1-8) The chromaticity coordinates (x, y) on the CIE-xy chromaticity diagram of the reflected light are outside the range bounded by 0.25 ≤ x ≤ 0.4 and 0.25 ≤ y ≤ 0.4.

[0022] A 14th aspect of the present invention is a solar cell module comprising a plurality of solar cells and a color adjustment plate disposed on the light-receiving surface side of the plurality of solar cells, wherein the color adjustment plate has a substrate and a dielectric multilayer film formed on the substrate, in which high refractive index layers and low refractive index layers are alternately stacked, and the dielectric multilayer film is configured to satisfy the following (1-1) to (1-3), (1-5), and (1-6); (1-1) When white light is incident from a vertical direction, the reflected light reflected in the same direction as the vertical direction exhibits spectral reflectance characteristics having multiple reflection peaks in the wavelength range of 380 nm to 780 nm. (1-2) The plurality of reflection peaks each include at least one first principal reflection peak with a wavelength of less than 520 nm and one second principal reflection peak with a wavelength of 520 nm or more. (1-3) The plurality of reflection peaks exhibit a reflectance of 20% or more relative to the reflection peak showing the highest reflectance among the reflection peaks in the wavelength range. (1-5) The full width at half maximum (FWHM) of at least one of the first principal reflection peak and the second principal reflection peak is 200 nm or less. (1-6) The reflectance of both the first principal reflect peak and the second principal reflect peak is 70% or less.

[0023] Aspect 15 of the present invention is a solar cell module according to aspect 14, wherein one of the surfaces of the substrate, the film-forming surface on which the dielectric multilayer film is formed and the non-film-forming surface on which the dielectric multilayer film is not formed, is formed as a diffuse reflecting surface having an uneven structure.

[0024] Aspect 16 of the present invention is a color adjustment plate in which the non-film-forming surface is formed as a diffuse reflecting surface, in the solar cell module of aspect 15.

[0025] Aspect 17 of the present invention is a solar cell module according to aspect 16, wherein the root mean square height Rq of the diffuse reflecting surface is 0.4 μm to 1.3 μm.

[0026] Aspect 18 of the present invention is a solar cell module in any one of aspects 14 to 17, wherein the substrate is a diffuser plate.

[0027] Aspect 19 of the present invention is a color adjustment plate comprising a two-dimensional transparent substrate and a dielectric multilayer film formed on the entire outer surface of the transparent substrate, wherein high refractive index layers and low refractive index layers are alternately stacked, and the dielectric multilayer film is configured to satisfy the following (1-1) to (1-3); (1-1) When white light is incident from a vertical direction, the reflected light reflected in the same direction as the vertical direction exhibits spectral reflectance characteristics having multiple reflection peaks in the wavelength range of 380 nm to 780 nm. (1-2) The plurality of reflection peaks each include at least one first principal reflection peak with a wavelength of less than 520 nm and one second principal reflection peak with a wavelength of 520 nm or more. (1-3) The plurality of reflection peaks exhibit a reflectance of 20% or more relative to the reflection peak showing the highest reflectance among the reflection peaks in the wavelength range.

[0028] Aspect 20 of the present invention is a color adjustment plate of aspect 19, wherein one of the surfaces of the substrate, the film-forming surface on which the dielectric multilayer film is formed and the non-film-forming surface on which the dielectric multilayer film is not formed, is formed as a diffuse reflective surface having an uneven structure.

[0029] Aspect 21 of the present invention is a color adjustment plate in which the non-film-forming surface is formed as a diffuse reflecting surface, in the case of the color adjustment plate of aspect 20.

[0030] Aspect 22 of the present invention is a color adjustment plate in any one of aspects 19 to 21, wherein the size of the transparent substrate is 1 μm to 1000 μm.

[0031] Aspect 23 of the present invention is a color adjustment plate in any one of aspects 19 to 22, wherein the transparent substrate is selected from the group consisting of natural mica, artificial mica, glass, and inorganic single crystal.

[0032] Aspect 24 of the present invention is a color adjustment plate in any one of aspects 19 to 23, wherein the substrate is a diffuser plate.

[0033] Aspect 25 of the present invention is a color adjustment plate in any one of aspects 19 to 24, wherein the plurality of reflection peaks are two reflection peaks.

[0034] Aspect 26 of the present invention is a color adjustment plate in any one of aspects 19 to 25, wherein the plurality of reflection peaks are three reflection peaks.

[0035] Aspect 27 of the present invention is a color adjustment plate in any one of aspects 19 to 26, wherein the plurality of reflection peaks are four reflection peaks.

[0036] Aspect 28 of the present invention is a color adjustment plate in any one of aspects 19 to 27, wherein the dielectric multilayer film is further configured to satisfy (1-4) below; (1-4) When the angle of incidence from the vertical is changed from 0° to 30°, the changes in the x and y coordinates of the chromaticity coordinates (x, y) on the CIE-xy chromaticity diagram of the reflected light are both 0.1 or less.

[0037] Aspect 29 of the present invention is a color adjustment plate in any one of aspects 19 to 28, wherein the dielectric multilayer film is further configured to satisfy the following (1-5); (1-5) The full width at half maximum (FWHM) of at least one of the first principal reflection peak and the second principal reflection peak is 200 nm or less.

[0038] Aspect 30 of the present invention is a color adjustment plate in any one of aspects 19 to 29, wherein the dielectric multilayer film is further configured to satisfy the following (1-6); (1-6) The reflectance of both the first principal reflect peak and the second principal reflect peak is 70% or less.

[0039] Aspect 31 of the present invention is a color adjustment plate in any one of aspects 19 to 30, wherein the dielectric multilayer film is further configured to satisfy the following (1-7); (1-7) The chromaticity coordinates (x, y) on the CIE-xy chromaticity diagram of the reflected light lie within the range bounded by 0.25 ≤ x ≤ 0.4 and 0.25 ≤ y ≤ 0.4.

[0040] Aspect 32 of the present invention is a color adjustment plate in any one of aspects 19 to 31, wherein the dielectric multilayer film is further configured to satisfy (1-8) below; (1-8) The chromaticity coordinates (x, y) on the CIE-xy chromaticity diagram of the reflected light are outside the range bounded by 0.25 ≤ x ≤ 0.4 and 0.25 ≤ y ≤ 0.4.

[0041] Aspect 33 of the present invention is a solar cell module comprising a plurality of solar cells and a color adjustment plate disposed on the light-receiving surface side of the plurality of solar cells, wherein the color adjustment plate has a plurality of two-dimensional transparent substrates and a dielectric multilayer film formed on the entire outer surface of the transparent substrates, in which high refractive index layers and low refractive index layers are alternately stacked, and the dielectric multilayer film is configured to satisfy the following (1-1) to (1-3), (1-5), and (1-6); (1-1) When white light is incident from a vertical direction, the reflected light reflected in the same direction as the vertical direction exhibits spectral reflectance characteristics having multiple reflection peaks in the wavelength range of 380 nm to 780 nm. (1-2) The plurality of reflection peaks each include at least one first principal reflection peak with a wavelength of less than 520 nm and one second principal reflection peak with a wavelength of 520 nm or more. (1-3) The plurality of reflection peaks exhibit a reflectance of 20% or more relative to the reflection peak showing the highest reflectance among the reflection peaks in the wavelength range. (1-5) The full width at half maximum (FWHM) of at least one of the first principal reflection peak and the second principal reflection peak is 200 nm or less. (1-6) The reflectance of both the first principal reflect peak and the second principal reflect peak is 70% or less.

[0042] Aspect 34 of the present invention is a solar cell module according to aspect 33, wherein one of the surfaces of the substrate, the film-forming surface on which the dielectric multilayer film is formed and the non-film-forming surface on which the dielectric multilayer film is not formed, is formed as a diffuse reflecting surface having an uneven structure.

[0043] Aspect 35 of the present invention is a solar cell module according to aspect 34, wherein the non-film-forming surface is formed as a diffuse reflecting surface.

[0044] Embodiment 36 of the present invention is a solar cell module in any one of embodiments 33 to 35, wherein the substrate is a diffuser plate.

[0045] Aspect 37 of the present invention is a method for manufacturing a color adjustment plate, which is any one of Aspect 1, Aspect 2, or Aspect 19, and comprises a dielectric multilayer determination step in which at least one parameter of the dielectric multilayer film, such as the material of the high refractive index layer and the low refractive index layer, the thickness of each layer, and the number of layers, is determined by optical thin film design simulation.

[0046] Aspect 38 of the present invention is a method for forming a dielectric multilayer film on a substrate or on the entire outer surface of a transparent substrate, wherein high refractive index layers and low refractive index layers are alternately stacked, and the method is characterized in that at least one parameter of the material of the high refractive index layer and the low refractive index layer, the thickness of each layer, and the number of layers is determined by optical thin film design simulation such that the dielectric multilayer film satisfies at least the following (1-1) to (1-3); (1-1) When white light is incident from a vertical direction, the reflected light reflected in the same direction as the vertical direction exhibits spectral reflectance characteristics having multiple reflection peaks in the wavelength range of 380 nm to 780 nm. (1-2) The plurality of reflection peaks each include at least one first principal reflection peak with a wavelength of less than 520 nm and one second principal reflection peak with a wavelength of 520 nm or more. (1-3) The plurality of reflection peaks exhibit a reflectance of 20% or more relative to the reflection peak showing the highest reflectance among the reflection peaks in the wavelength range.

[0047] Aspect 39 of the present invention is a film deposition apparatus for forming a dielectric multilayer film in which high refractive index layers and low refractive index layers are alternately stacked on a substrate or on the entire outer surface of a transparent substrate, the apparatus comprising optical parameter determination means for determining at least one parameter of the material of the high refractive index layer and the low refractive index layer, the thickness of each layer, and the number of layers by optical thin film design simulation such that the dielectric multilayer film satisfies at least the following (1-1) to (1-3); (1-1) When white light is incident from a vertical direction, the reflected light reflected in the same direction as the vertical direction exhibits spectral reflectance characteristics having multiple reflection peaks in the wavelength range of 380 nm to 780 nm. (1-2) The plurality of reflection peaks each include at least one first principal reflection peak with a wavelength of less than 520 nm and one second principal reflection peak with a wavelength of 520 nm or more. (1-3) The plurality of reflection peaks exhibit a reflectance of 20% or more relative to the reflection peak showing the highest reflectance among the reflection peaks in the wavelength range.

[0048] A 40 embodiment of the present invention comprises a substrate and a dielectric multilayer film in which high refractive index layers and low refractive index layers are alternately laminated on at least one of the front and back surfaces of the substrate, The dielectric multilayer film is configured to satisfy the following conditions (1-1) to (1-3) and is used as a color adjustment plate; (1-1) When white light is incident from a vertical direction, the reflected light reflected in the same direction as the vertical direction exhibits spectral reflectance characteristics having multiple reflection peaks in the wavelength range of 380 nm to 780 nm. (1-2) The plurality of reflection peaks each include at least one first principal reflection peak with a wavelength of less than 520 nm and one second principal reflection peak with a wavelength of 520 nm or more. (1-3) The plurality of reflection peaks exhibit a reflectance of 20% or more relative to the reflection peak showing the highest reflectance among the reflection peaks in the wavelength range.

[0049] Aspect 41 of the present invention is a color adjustment plate of aspect 40, wherein the substrate is a diffuser plate.

[0050] Aspect 42 of the present invention is a solar cell module comprising a plurality of solar cells and a color adjustment plate disposed on the light-receiving surface side of the plurality of solar cells, wherein the color adjustment plate has a substrate and an inorganic pigment-containing layer containing an inorganic pigment formed on at least one of the front surface and the back surface of the substrate, and one of the surfaces of the substrate, which is a film-forming surface on which the inorganic pigment-containing layer is formed and which is a non-film-forming surface on which the inorganic pigment-containing layer is not formed, is formed as a diffuse reflective surface having an uneven structure or is a diffuse plate.

[0051] Aspect 43 of the present invention is a solar cell module according to aspect 42, wherein the root mean square height Rq of the diffuse reflecting surface is 0.1 μm to 2.0 μm. [Effects of the Invention]

[0052] The color adjustment plate of the present invention provides a color adjustment plate with low angle dependence. [Brief explanation of the drawing]

[0053] [Figure 1] This is a schematic cross-sectional view of a color adjustment plate according to one embodiment. [Figure 2] Figure 1 is a schematic cross-sectional view of an enlarged portion of the dielectric multilayer film of the color adjustment plate shown. [Figure 3] This is an example of the reflection spectrum of reflected light when white light is perpendicularly reflected from a dielectric multilayer film on a color adjustment plate. [Figure 4] This is a conceptual diagram illustrating the reflection of light in a dielectric multilayer film. [Figure 5] This is a CIE-xy chromaticity diagram. [Figure 6] This diagram explains how to interpret the xy chromaticity diagram. [Figure 7] This is a diagram to explain the dominant wavelength. [Figure 8] (a) shows the chromaticity coordinates on the xy chromaticity diagram for the reflected light of the reflection spectrum illustrated in Figure 3, and (b) shows the parameters of the dielectric multilayer model used in the simulation. [Figure 9] (a) shows the dependence of reflected white light incident on the dielectric multilayer film of the first embodiment on the incident angle, as shown by shifting the chromaticity coordinates on the xy chromaticity diagram, and (b) is a schematic diagram showing how incident light is reflected at each incident angle. [Figure 10] The upper limit of the wavelength range of the reflection spectrum shown in Figure 3 has been extended to 1200 nm. [Figure 11](a) shows the chromaticity coordinates on the xy chromaticity diagram for the reflection spectrum of white light incident on the dielectric multilayer film of the second embodiment, and (b) shows the parameters of the dielectric multilayer film model used in the simulation. [Figure 12] This shows the reflection spectrum of the reflected light when white light is perpendicularly reflected from the dielectric multilayer film of the second embodiment. [Figure 13] (a) shows the reflection spectra of white light incident on the dielectric multilayer film of the second embodiment at various incident angles, and (b) shows the chromaticity coordinates of the first and second principal reflection peaks at each incident angle on the xy chromaticity diagram. [Figure 14] (a) is an enlarged view of the xy chromaticity diagram in Figure 13(b) showing the portion where the chromaticity coordinates of the first and second principal reflection peaks exist, and (b) shows the chromaticity coordinates of the reflection spectrum for each incident angle on the xy chromaticity diagram. [Figure 15] (a) shows the chromaticity coordinates on the xy chromaticity diagram for the reflection spectrum of white light incident on the dielectric multilayer film of the third embodiment, and (b) shows the parameters of the dielectric multilayer film model used in the simulation. [Figure 16] This shows the reflection spectrum of the reflected light when white light is perpendicularly reflected from the dielectric multilayer film of the third embodiment. [Figure 17] The chromaticity coordinates of the reflection spectra at various incident angles when white light is incident on the dielectric multilayer film of the third embodiment are shown on the xy chromaticity diagram. [Figure 18] (a) shows the chromaticity coordinates on the xy chromaticity diagram for the reflection spectrum of white light incident on the dielectric multilayer film of the fourth embodiment, and (b) shows the parameters of the dielectric multilayer film model used in the simulation. [Figure 19] This shows the reflection spectrum of the reflected light when white light is perpendicularly reflected from the dielectric multilayer film of the fourth embodiment. [Figure 20] The chromaticity coordinates of the reflection spectra at various incident angles when white light is incident on the dielectric multilayer film of the fourth embodiment are shown on the xy chromaticity diagram. [Figure 21]This shows the chromaticity coordinates on the xy chromaticity diagram for the reflection spectrum of white light incident on the dielectric multilayer film of the fifth embodiment. [Figure 22] This shows the reflection spectrum of the reflected light when white light is perpendicularly reflected from the dielectric multilayer film of the fifth embodiment. [Figure 23] The chromaticity coordinates of the reflection spectra at various incident angles when white light is incident on the dielectric multilayer film of the fifth embodiment are shown on the xy chromaticity diagram. [Figure 24] This shows the chromaticity coordinates on the xy chromaticity diagram for the reflection spectrum of white light incident on the dielectric multilayer film of the sixth embodiment. [Figure 25] This shows the reflection spectrum of the reflected light when white light is perpendicularly reflected from the dielectric multilayer film of the sixth embodiment. [Figure 26] The chromaticity coordinates of the reflection spectra at various incident angles when white light is incident on the dielectric multilayer film of the sixth embodiment are shown on the xy chromaticity diagram. [Figure 27] (a) shows the chromaticity coordinates on the xy chromaticity diagram for the reflection spectrum of white light incident on the dielectric multilayer film of the seventh embodiment, and (b) shows the parameters of the dielectric multilayer film model used in the simulation. [Figure 28] This shows the chromaticity coordinates on the xy chromaticity diagram for the reflection spectrum of white light incident on the dielectric multilayer film of the 7th embodiment. [Figure 29] The chromaticity coordinates of the reflection spectra at various incident angles when white light is incident on the dielectric multilayer film of the 7th embodiment are shown on the xy chromaticity diagram. [Figure 30] (a) shows the chromaticity coordinates on the xy chromaticity diagram for the reflection spectrum of white light incident on the dielectric multilayer film of the eighth embodiment, and (b) shows the parameters of the dielectric multilayer film model used in the simulation. [Figure 31] This shows the chromaticity coordinates on the xy chromaticity diagram for the reflection spectrum of white light incident on the dielectric multilayer film of the 8th embodiment. [Figure 32] The chromaticity coordinates of the reflection spectra at various incident angles when white light is incident on the dielectric multilayer film of the 8th embodiment are shown on the xy chromaticity diagram. [Figure 33] This is a schematic cross-sectional view of the color adjustment plate according to the ninth embodiment. [Figure 34] (a) shows the chromaticity coordinates on the xy chromaticity diagram for the reflection spectrum of white light incident on the dielectric multilayer film of the ninth embodiment, and (b) shows the parameters of the dielectric multilayer film model used in the simulation. [Figure 35] This shows the chromaticity coordinates on the xy chromaticity diagram for the reflection spectrum of white light incident on the dielectric multilayer film of the ninth embodiment. [Figure 36] The chromaticity coordinates of the reflection spectra at various incident angles when white light is incident on the dielectric multilayer film of the ninth embodiment are shown on the xy chromaticity diagram. [Figure 37] (a) shows the chromaticity coordinates on the xy chromaticity diagram for the reflection spectrum of white light incident on the dielectric multilayer film of the 10th embodiment, and (b) shows the parameters of the dielectric multilayer film model used in the simulation. [Figure 38] This shows the chromaticity coordinates on the xy chromaticity diagram for the reflection spectrum of white light incident on the dielectric multilayer film of the 10th embodiment. [Figure 39] This is a schematic cross-sectional view showing an example of how to use the color adjustment plate according to the present invention. [Figure 40] This is a schematic cross-sectional view showing an example of how to use the color adjustment plate according to the present invention. [Figure 41] (a) to (c) show schematic cross-sectional diagrams of the color adjustment plate according to the present invention, in which either the film-forming surface or the non-film-forming surface of the substrate is a diffuse reflective surface, and (d) shows a schematic cross-sectional diagram of the graph of the whiteness of a glass substrate having a diffuse reflective surface. [Figure 42] Figures 41(a) to 41(c) show the percentage reduction in short-circuit current ΔJsc(%) for a solar cell module using a color adjustment plate with a schematic cross-sectional view, and Figure 41(d) shows the graph of the results of measuring the percentage reduction in short-circuit current ΔJsc(%) for a solar cell module using a substrate with a schematic cross-sectional view. [Figure 43]These are optical microscope images of the diffuse reflection surface of a glass substrate that has been sandblasted using abrasive grains. (a) shows the result using #600 abrasive grains, (b) shows the result using #400 abrasive grains, and (c) shows the result using #220 abrasive grains. [Figure 44] Figures 43(a) to (c) show the arithmetic mean roughness Ra, maximum height Ry, and root mean square height Rq for each of the XX lines. [Figure 45] This is a schematic cross-sectional view showing a part of the solar cell module according to the present invention. [Figure 46] This graph shows the relationship between the surface roughness of the diffuse reflecting surface and the rate of decrease ΔJsc of the short-circuit current of the solar cell module. [Figure 47] This graph shows the relationship between the surface roughness of the diffuse reflecting surface and the whiteness of the color adjustment plate of the solar cell module. [Figure 48] This is a schematic cross-sectional view showing a part of a solar cell module according to another embodiment of the present invention. [Modes for carrying out the invention]

[0054] The present invention will now be described in detail with reference to the drawings as appropriate. The drawings used in the following description may show enlarged versions of key features for convenience in order to clearly illustrate the features of the present invention, and the dimensional ratios of each component may differ from those of the actual components. The materials, dimensions, etc., exemplified in the following description are merely examples, and the present invention is not limited to them. It is possible to modify and implement the invention as appropriate within the scope of achieving its effects. Furthermore, even configurations described in only one embodiment can be appropriately applied to other embodiments.

[0055] Figure 1 is a schematic cross-sectional view of the color adjustment plate according to this embodiment. Figure 2 is an enlarged schematic cross-sectional view of the dielectric multilayer film portion of the color adjustment plate shown in Figure 1. Figure 3 is an example of the reflection spectrum of the reflected light when white light is incident perpendicularly on the dielectric multilayer film of the color adjustment plate and reflected perpendicularly.

[0056] (Color adjustment plate (first embodiment)) The color adjustment plate 10 shown in Figure 1 comprises a substrate 1 and a dielectric multilayer film 2 formed on the substrate 1, in which high refractive index layers and low refractive index layers are alternately stacked. Furthermore, the dielectric multilayer film 2 is configured to satisfy the following conditions (1-1) to (1-3); (1-1) When white light is incident from a vertical direction, the reflected light reflected in the same direction as the vertical direction exhibits spectral reflectance characteristics having multiple reflection peaks in the wavelength range of 380 nm to 780 nm. (1-2) The plurality of reflection peaks each include at least one first principal reflection peak with a wavelength of less than 520 nm and one second principal reflection peak with a wavelength of 520 nm or more. (1-3) The plurality of reflection peaks exhibit a reflectance of 20% or more relative to the reflection peak showing the highest reflectance among the reflection peaks in the wavelength range. Here, "color-adjusted plate" refers to a plate equipped with a dielectric multilayer film whose color has been adjusted by the parameters of the high-refractive-index layer and low-refractive-index layer constituting the dielectric multilayer film, and its application is not particularly limited.

[0057] <Uses of color adjustment boards> Color adjustment plates can be applied to a variety of uses. Color adjustment plates can be used, for example, to color the appearance of solar cell modules. In this case, it is necessary to color the modules while minimizing the energy of reflected light in order to suppress the decrease in the conversion efficiency of the solar cells as much as possible. The required colors vary from one perspective to another, considering factors such as maintaining the landscape of the installation site of the solar cell modules and design aesthetics, but any color is possible. Furthermore, when used for decorative purposes (a method of changing the appearance without changing the function), there are no particular restrictions on the use of color adjustment panels. Larger examples include installation on the walls of buildings, use on the exterior panels of mobile vehicles such as automobiles, buses, trains, and bicycles, and use on various display boards such as traffic signs, billboards, and bulletin boards. Smaller examples include attachment to the tops and sides of personal information and electronic devices and small boxes, communication terminals such as mobile phones and smartphones, and electrical equipment such as vending machines and lighthouses.

[0058] <Circuit board> Various substrates can be used depending on the application in which the color adjustment plate is used. For example, when a color adjustment plate is used as a coloring component on the light-receiving surface side of a solar cell, the substrate 1 may be a transparent substrate that can transmit visible light, such as various glass substrates, plastic substrates made of polycarbonate resin or acrylic resin, transparent inorganic material substrates other than glass, or mica. Furthermore, when used for decorative purposes on color-adjustment boards, any substrate on which a dielectric multilayer film can be formed can be used without any particular limitations.

[0059] From the viewpoint of forming a dielectric multilayer film on the substrate 1, it is generally preferable that the surface (the film-forming surface on which the dielectric multilayer film is formed) is flat. However, even if the substrate has some degree of unevenness, it can be used as long as it functions as a color adjustment plate, or if it can enhance its function as a color adjustment plate. In this case, the size of the unevenness is, for example, several tens of nanometers to several tens of micrometers.

[0060] Furthermore, the substrate 1 can be configured to have a textured surface on the film-forming surface where the dielectric multilayer film is formed, or on the non-film-forming surface where the dielectric multilayer film is not formed, to provide a diffuse reflection function. This configuration can improve the performance of the color adjustment plate. This configuration will be described in detail later. In this specification, a surface of the substrate 1 that has a film-forming surface or a non-film-forming surface and is equipped with an uneven structure to provide a diffuse reflection function may be referred to as a "diffuse reflection surface."

[0061] Furthermore, the substrate 1 may be a diffuser plate. Typical types of diffusers include those containing light-diffusing particles and those with an uneven surface. However, the one used as substrate 1 is a diffuser with an uneven surface. Therefore, the diffuser is also a substrate equipped with a diffuse reflective surface having an uneven structure. As a diffuser plate having an uneven surface, commercially available frosted glass can be used, for example. For example, frosted glass diffusers (e.g., N-BK7 frosted glass diffuser), reflective diffusers (e.g., N-BK7 reflective diffuser), and engineered diffusers from THORLABS can be used. For example, #120, #220, #600, and #1500 grits can be used.

[0062] (Dielectric multilayer film) The dielectric multilayer film 2 is a multilayer film in which high refractive index layers 2a and low refractive index layers 2b are alternately stacked from the substrate 1 side. The number of high refractive index layers 2a and low refractive index layers 2b is not particularly limited and can be any number. Dielectric multilayer films are multilayer films in which high-refractive-index layers and low-refractive-index layers are alternately stacked. Depending on the combination of materials for the high-refractive-index and low-refractive-index layers (mainly the combination of high and low refractive indices), the layer thickness (film thickness), and the number of layers, they can have a variety of spectral reflectance characteristics. In the dielectric multilayer film 2 shown in Figure 2, high refractive index layers 2a and low refractive index layers 2b are alternately stacked from the substrate 1 side, but low refractive index layers 2b and high refractive index layers 2a may also be alternately stacked from the substrate 1 side. Furthermore, the topmost refractive index layer can be either a high refractive index layer 2a or a low refractive index layer 2b.

[0063] The refractive index of the high refractive index layer 2a is, for example, 1.91 to 3.4. Examples of dielectric materials used in the high refractive index layer 2a include titanium oxide (TiO2, refractive index 2.33-2.55), niobium pentoxide (Nb2O5, refractive index 2.33), cerium oxide (CeO2, refractive index 2.18-2.52), hafnium oxide (HfO2, refractive index 2.15), indium oxide (In2O3, refractive index 2.00), silicon (Si, refractive index 3.4), silicon monoxide (SiO, refractive index 2.0), tantalum pentoxide (Ta2O5, refractive index 2.2-2.4), zinc oxide (ZnO, refractive index 2.1), zinc sulfide (ZnS, refractive index 2.31-2.38), and zirconium oxide (ZrO2, refractive index 1.95-2.05).

[0064] The refractive index of the low refractive index layer 2b is, for example, 1.38 to 1.9. Examples of dielectric materials used in the low refractive index layer 2b include silicon dioxide (SiO2, refractive index 1.46), magnesium fluoride (MgF2, refractive index 1.38), aluminum oxide (Al2O3, refractive index 1.59-1.62), gadolinium oxide (Gd2O3, refractive index 1.8), magnesium oxide (MgO, refractive index 1.70-1.75), selenium trioxide (Se2O3, refractive index 1.89), and yttrium oxide (Y2O3, refractive index 1.89).

[0065] The film thicknesses of the high refractive index layer 2a and the low refractive index layer 2b can be appropriately selected according to the desired spectral reflectance characteristics. The film thickness of the high refractive index layer 2a can be, for example, 0.1 nm to 1000 nm. The film thickness of the low refractive index layer 2b can be, for example, 0.1 nm to 1000 nm.

[0066] Furthermore, other layers may be present between the substrate 1 and the dielectric multilayer film 2, as long as the effects of the present invention are achieved. For example, an adhesion layer may be present to improve the adhesion between the substrate 1 and the dielectric multilayer film 2.

[0067] The dielectric multilayer film 2 is configured to satisfy the following conditions (1-1) to (1-3): (1-1) When white light is incident from a vertical direction, the reflected light reflected in the same direction as the vertical direction exhibits spectral reflectance characteristics having multiple reflection peaks in the wavelength range of 380 nm to 780 nm. (1-2) The plurality of reflection peaks each include at least one first principal reflection peak with a wavelength of less than 520 nm and one second principal reflection peak with a wavelength of 520 nm or more. The multiple reflection peaks in (1-3)(1-1) are those that exhibit a reflectance of 20% or more relative to the reflection peak showing the highest reflectance among the reflection peaks in the above wavelength range.

[0068] The range "380nm to 780nm" in (1-1) may also be "400nm to 700nm" from the perspective of visible light. Similarly, the lower limit may be 390nm or 410nm, and the upper limit may be 770nm, 760nm, 750nm, 740nm, 730nm, 720nm, or 710nm.

[0069] Based on the requirements of (1-1) to (1-3), the "first primary reflectance peak" in (1-2) is a reflectance peak with a wavelength between 380 nm and less than 520 nm, and exhibits a reflectance of 20% or more relative to the reflectance peak showing the maximum reflectance. There is not limited to one "first primary reflectance peak," but there may be multiple. Also, the "second primary reflectance peak" in (1-2) is a reflectance peak with a wavelength between 520 nm and 780 nm, and exhibits a reflectance of 20% or more relative to the reflectance peak showing the maximum reflectance. There is not limited to one "second primary reflectance peak," but there may be multiple.

[0070] Since (1-3) is "20% or more", the aforementioned multiple reflection peaks do not include reflection peaks that have little effect on color. Therefore, the requirement of (1-3) is preferably "25% or more", and more preferably "30% or more".

[0071] Furthermore, in (1-1) "multiple reflection peaks in the wavelength range of 380 nm to 780 nm", it is preferable that none of the reflection peaks in the above wavelength range have a reflectance of 5% or less relative to the reflection peak showing the maximum reflectance, more preferably none have a reflectance of 10% or less, even more preferably none have a reflectance of 15% or less, and most preferably none have a reflectance of less than 20%.

[0072] (1-1) and (1-3) indicate that there are multiple dominant reflection peaks in determining the color of the reflected light of the dielectric multilayer film according to the present invention. The number of these "multiple reflection peaks" is preferably two, three, or four. Furthermore, (1-2) helps to suppress the blue shift of reflected light when the angle of incidence is large. The blue shift will be discussed later.

[0073] (1-1) to (1-3) will be explained using the reflection spectrum illustrated in Figure 3. This reflection spectrum was obtained by simulation using the optical thin film design software "OptiLayer" (OptiLayer Inc.), and the parameters of the dielectric multilayer model used are shown in Figure 8(b). Hereafter, this dielectric multilayer film will be referred to as the dielectric multilayer film of the first embodiment.

[0074] The reflection spectrum shown in Figure 3 has four reflection peaks, p11 to p14, in the wavelength range from 380 nm to 780 nm. Of the four reflection peaks p11 to p14, reflection peak p11 shows the highest reflectivity. As defined in (1-3), the "multiple reflection peaks" in (1-1) are limited to those that exhibit a reflectance of 20% or more relative to the reflection peak p11, which exhibits the maximum reflectance. Therefore, reflection peaks p12 and p14 are not included in the "multiple reflection peaks" in (1-1). Consequently, the "multiple reflection peaks" in (1-1) consist only of reflection peaks p11 and p13. Of these, reflection peak p11, which has a reflection peak near a wavelength of 400 nm, corresponds to the "first principal reflection peak" in (1-2), and reflection peak p13, which has a reflection peak near a wavelength of 560 nm, corresponds to the "second principal reflection peak" in (1-2).

[0075] The configuration described above (1-2) is, as stated above, intended to suppress blue shift. Blue shift is a phenomenon in which the reflectance wavelength characteristics of a dielectric multilayer film shift to shorter wavelengths as the angle of incidence of light entering the film increases. Blue shift will be explained using a diagram.

[0076] Figure 4 is a conceptual diagram illustrating the reflection of light in a dielectric multilayer film. To facilitate understanding, only the essential parts are shown in Figure 4. In Figure 4, the label 2A represents a portion of a dielectric multilayer film in which a high refractive index layer 2Aa (film thickness: d1) having a first refractive index n1 and a low refractive index layer 2Ab (film thickness: d2) having a second refractive index n2 are alternately stacked in multiple layers. In Figure 4, the film thickness of the two high refractive index layers 2Aa is indicated by label d1, but this does not mean they are the same thickness; the film thickness of each high refractive index layer is appropriately determined to achieve the desired optical properties. The same applies to the film thickness of the low refractive index layer.

[0077] We will explain this by comparing the reflected light when the light is incident perpendicularly with the reflected light when the light is incident at an incident angle θ1. When white light is incident on a dielectric multilayer film 2A, a portion of the incident light is reflected at the interface between the high refractive index layer 2Aa and the low refractive index layer 2Ab, while the rest is refracted (refractive angle: θ2) and transmitted. Since the interface between the high refractive index layer and the low refractive index layer appears repeatedly, the reflected light generated at each interface interferes. When light is incident perpendicularly on the dielectric multilayer film, the position of the light traveling back and forth within the layer and the position of the light reflected from the surface are the same, so the difference in the optical path lengths of the two beams of light is equal to the optical path length of the light traveling back and forth within the layer. However, when an angle of incidence is introduced, a discrepancy occurs between the position of the reflected light and the incident position of the light traveling back and forth within the layer. In the case of non-perpendicular incidence, the optical path length n1b is generated by the discrepancy between the position of the reflected light and the incident position of the light traveling back and forth within the layer. On the other hand, the difference between the optical path length 2n2a of the light traveling back and forth within the layer and the optical path length n1b is the optical path length difference S caused by the incident angle θ1 of the parallel plane substrate (S = 2n2a - n1b). As the angle of incidence θ1 of the incident light is gradually increased, the difference in optical path length of the reflected light generated at each interface gradually decreases, and shorter wavelength light interferes and reinforces each other. Therefore, the more obliquely (closer to an angle parallel to the surface) the dielectric multilayer film 2 illuminated by white light is viewed, the more strongly shorter wavelength light appears to be reflected. In other words, the larger the angle of incidence θ1, the more the reflected light appears bluish. This phenomenon is called blue shift. The angle of incidence is defined as the angle between the perpendicular to the plane of incidence and the optical axis of the incident light.

[0078] <xy chromaticity diagram> Figure 5 is an xy chromaticity diagram (CIE-xy chromaticity diagram) based on the specifications of the CIE (International Commission on Illumination). Figure 6 is a diagram for explaining how to view the xy chromaticity diagram.

[0079] The most basic characteristics of human color perception are hue, saturation, and lightness (whiteness). Hue means the types of colors such as red, yellow, green, cyan, blue, and magenta, that is, the colors of light with different wavelengths perceived by the human eye. Saturation means the vividness and purity of the color. When the saturation is high, it approaches a pure color, and when the saturation is low, it approaches an achromatic color (white to gray). Lightness means the brightness of the color.

[0080] In the XYZ color system, the numerical values represented by X, Y, and Z are called tristimulus values. However, since it is difficult to immediately judge the color by looking at the values of X, Y, and Z, it is common to express them using a chromaticity diagram based on the ratio of tristimulus values (the color mixture ratio of the three primary stimuli). The color mixture ratios x, y, and z of X, Y, and Z are expressed as x = X / (X + Y + Z), y = Y / (X + Y + Z), and z = Z / (X + Y + Z), respectively, and x + y + z = 1 (100%). Since the value of z can be known if x and y are known, the xy chromaticity diagram is expressed using only x and y without showing the value of z.

[0081] <Hue in the xy chromaticity diagram> As shown in Figures 5 and 6, the xy chromaticity diagram has a horseshoe shape (or bell shape) with x on the horizontal axis and y on the vertical axis. The outer peripheral curve that curves in a horseshoe shape is called the spectral locus or monochromatic light locus, and the straight part is called the pure purple locus. The chromaticity coordinates (x, y) around (0.333, 0.333) slightly below the center of the horseshoe shape are achromatic (white to gray). Centering on this achromatic color, hues such as yellowish red, yellow, yellowish green, green, bluish green, blue, and purplish blue are sequentially arranged counterclockwise from the rightmost red on the spectral locus. Monochromatic light of each hue is arranged on the spectral locus, and all the colors inside this spectral locus are mixed light.

[0082] <Saturation in the xy chromaticity diagram> The saturation increases radially outward from the area centered on the chromaticity coordinates (x, y) = (0.333, 0.333). The colors with the highest saturation among those hues are arranged on the outermost spectral locus (monochromatic light locus) and the pure purple locus.

[0083] <Brightness in the xy chromaticity diagram> In the XYZ color space, the lightness (L * ) of an object color is represented by the luminous reflectance (transmittance) Y. All the colors on a certain xy chromaticity diagram are composed of colors with the same luminous reflectance Y value, that is, the same lightness. In many cases, the achromatic area is drawn white in the xy chromaticity diagram, which is the case when the luminous reflectance Y value is large (bright). As the value of Y decreases (darkens), the entire xy chromaticity diagram becomes darker. Thus, the xy chromaticity diagram has a multi-layer structure for each luminous reflectance Y value (brightness). Because of such a multi-layer structure, the XYZ color space is sometimes referred to as the Yxy color space. Hereinafter, the achromatic point (x, y) = (0.333, 0.333) may also be referred to as the white point, which indicates the case when the Y value is large.

[0084] In the xy chromaticity diagram, the color of light is represented by two numerical values of the x coordinate and the y coordinate. However, it is not easy to associate the color from these two numbers. Therefore, it is practical to be able to associate the color with one number even at the sacrifice of some accuracy. To meet this requirement, the dominant wavelength is used. Using Fig. 7, the dominant wavelength is explained. For example, when there is a color F(0.41, 0.42) on the xy chromaticity diagram, draw a straight line from the white point W(0.333, 0.333) towards F, and further extend this straight line until it hits the spectral locus. Let the point where it hits be S. Since the chromaticity of the monochromatic light with a wavelength of 575 nm uniquely corresponds to this point S, the wavelength of this monochromatic light is taken as the dominant wavelength of the color F. In other words, the dominant wavelength is the wavelength of the monochromatic light when a certain color is made by mixing white light and monochromatic light. The dominant wavelengths are indicated numerically on the spectral locus in the chromaticity diagram. In the xy chromaticity diagram, the hue corresponds to the wavelength of the dominant wavelength.

[0085] In Fig. 8(a), the chromaticity coordinates c0 = (0.330, 0.325) on the xy chromaticity diagram are shown for the reflected light of the reflection spectrum illustrated in Fig. 3. W on the xy chromaticity diagram represents the chromaticity coordinates (0.333, 0.333) of white light (achromatic color). Fig. 8(b) shows the parameters of the dielectric multilayer film model used in the simulation. It can be seen that the reflected light of the reflection spectrum illustrated in Fig. 3 has chromaticity coordinates close to white (achromatic color).

[0086] <Incidence angle dependence> Next, the incidence angle dependence of the reflected light will be explained using the xy chromaticity diagram. Fig. 9(a) shows the chromaticity coordinates of the reflection spectra obtained by simulating each reflection spectrum when white light is incident on the dielectric multilayer film from normal incidence (incidence angle: 0°) with an increase in the incidence angle by 5° each using the optical thin film design software "OptiLayer" (OptiLayer Co., Ltd.) on the xy chromaticity diagram. Fig. 9(b) is a diagram schematically showing the state where light is incident on the dielectric multilayer film at each incidence angle and is reflected at the corresponding reflection angle (the direction in which the reflection spectrum is obtained).

[0087] On the xy chromaticity diagram shown in Fig. 9(a), the symbol W represents the chromaticity coordinates of white, and the symbol c 10 represents the chromaticity coordinates of the reflection spectrum at normal incidence, and the symbols c 11 , the symbol c 12 , the symbol c 13 , the symbol c 14 , the symbol c 15 , the symbol c 16 respectively represent the chromaticity coordinates of the reflection spectra when incident at incidence angles of 5°, 10°, 15°, 20°, 25°, and 30°. The chromaticity coordinates of the reflection spectra at each incidence angle are as follows: W = (0.333, 0.333), c 10 = (0.325, 0.336), c 11 = (0.325, 0.346), c 12=(0.322, 0.375), c 13 =(0.309, 0.415), c 14 =(0.280, 0.446), c 15 =(0.235, 0.441), c 16 =(0.186, 0.391).

[0088] In Figure 9(a), it can be seen that as the angle of incidence increases from perpendicular incidence, the hue changes from a yellowish color at an incidence angle of 0°, to a yellowish-green color, then to a greenish color, and finally to a bluish color at an incidence angle of 30°. This phenomenon, where the color changes to a bluish color as the angle of incidence changes, is called the blue shift.

[0089] The reflection spectrum shown in Figure 10 is obtained by extending the upper limit of the wavelength range of the reflection spectrum shown in Figure 3 to 1200 nm. Figure 10 also shows a typical example of the wavelength dependence of the external quantum efficiency of a solar cell module. The reflection spectrum shown in Figure 10 satisfies the above conditions (1-1) to (1-3), as explained using Figure 3. Specifically, the reflection peaks p11 and p13 in the reflection spectrum have peak wavelengths of approximately 390 nm and 560 nm, respectively (satisfying (1-1)), the wavelength of reflection peak p11 is less than 520 nm, and the wavelength of reflection peak p13 is 520 nm or greater (satisfying (1-2)), and the reflectance of reflection peak p13 (approximately 33%) is 37% of the reflectance of reflection peak p11 (approximately 90%), which shows the highest reflectance (satisfying (1-3)).

[0090] From the reflection spectrum shown in Figure 10, it can be seen that both reflection peak p11 and reflection peak p13 have a full width at half maximum (FWHM) of 100 nm or less. A narrow full width at half maximum (FWHM) of the reflection peak means that when the color adjustment plate of the present invention is used in a solar cell module, the reflected light energy is suppressed, and as a result, the decrease in power generation efficiency can be suppressed, which is desirable. From this perspective, for a reflection peak that satisfies (1-1) to (1-3) above, at least one of the reflection peaks preferably has a full width at half maximum (FWHM) of 200 nm or less, more preferably 150 nm or less, and even more preferably 100 nm or less. This color adjustment plate is equipped with a dielectric multilayer film as a reflective film that exhibits a reflection spectrum having two narrowband reflection peaks.

[0091] Furthermore, the external quantum efficiency of the solar cell module shown in Figure 10 begins to decrease from approximately 600 nm, reaching 0.8 at approximately 480 nm, 0.6 at approximately 420 nm, and 0.5 at approximately 390 nm. Therefore, in terms of suppressing a decrease in power generation efficiency when using the color adjustment plate of the present invention in a solar cell module, it is preferable that the "first principal reflection peak" is closer to 380 nm, which is the lower limit of the wavelength range of requirement (1-1), and it is also preferable that the "second principal reflection peak" is closer to 520 nm, which is the lower limit of the wavelength range of requirement (1-1). Furthermore, from the viewpoint of suppressing a decrease in power generation efficiency, it is preferable that the reflectance of the "first main reflection peak" and the "second main reflection peak" be 70% or less. In particular, from the viewpoint of the wavelength dependence of the external quantum efficiency shown in Figure 10, the reflectance of the "second main reflection peak" is more effective than the reflectance of the "first main reflection peak" in suppressing the decrease in power generation efficiency, so it is preferable that the reflectance of the "second main reflection peak" be low. For example, it is preferable that the reflectance of the "second main reflection peak" be 60% or less, more preferably 50% or less, and even more preferably 40% or less.

[0092] (Color adjustment plate (second embodiment)) The color adjustment plate according to the second embodiment comprises a dielectric multilayer film that has a lower incidence angle dependence than the dielectric multilayer film of the first embodiment.

[0093] The optical properties of the dielectric multilayer films of the two embodiments having the above characteristics will be described. Figure 11(a) shows the chromaticity coordinate c on the xy chromaticity diagram for the reflected light when white light is perpendicularly incident on the dielectric multilayer film of the second embodiment. 20This shows (0.330, 0.330). Figure 11(b) shows the parameters of the dielectric multilayer model used in the simulation. Figure 12 shows the reflection spectrum when white light is perpendicularly incident on the dielectric multilayer of the second embodiment.

[0094] The reflection spectrum shown in Figure 12 has two reflection peaks p21 and p22 that satisfy the requirements (1-1) to (1-3) above. Specifically, reflection peaks p21 and p22 have peak wavelengths near 480 nm and 620 nm, respectively, within the wavelength range of 380 nm to 780 nm. Furthermore, reflection peaks p21 and p22 are the first principal reflection peak with a wavelength less than 520 nm and the second principal reflection peak with a wavelength of 520 nm or more, respectively, and the reflectance of reflection peak p22 is 20% or more of that of reflection peak p21, which exhibits the highest reflectance. Thus, although the dielectric multilayer film of the second embodiment has different reflection characteristics from the dielectric multilayer film of the first embodiment, it can be seen that it exhibits a reflection spectrum with a chromaticity coordinate close to white light (achromatic) to the same extent as the dielectric multilayer film of the first embodiment.

[0095] <Incidence angle dependence> The dependence of reflected light on the incident angle of the dielectric multilayer film of the second embodiment will be explained. In this example, we focus on the first and second principal reflection peaks and explain the dependence of the reflected light on the angle of incidence from their dependence on the angle of incidence. Figure 13(a) shows the results of a simulation using optical thin film design software for the reflection spectra at each incidence angle, increasing by 5° increments from perpendicular incidence. It can be seen that a first and second primary reflection peak exist in all reflection spectra. Figure 13(b) shows the chromaticity coordinates of the first and second primary reflection peaks at each incidence angle on the xy chromaticity diagram. In Figure 13(b), the dotted line connects the wavelength of the spectral trajectory at 520 nm to white light (W). Figure 14(a) is a magnified view of the xy chromaticity diagram in Figure 13(b), showing the portion where the chromaticity coordinates of the first and second principal reflection peaks exist. Figure 14(b) shows the chromaticity coordinates of the reflection spectrum for each incident angle on the xy chromaticity diagram.

[0096] In Figure 13(b), it can be seen that both the first and second primary reflection peaks are blue-shifted. The chromaticity coordinates of the first and second primary reflection peaks at each incidence angle are positioned symmetrically across the area near white (achromatic) W (hereinafter, the area enclosed by 0.25≦x≦0.4 and 0.25≦y≦0.4 on the xy chromaticity diagram may be referred to as the achromatic vicinity area). Therefore, the chromaticity coordinates of the reflection spectra at each incidence angle are all located in the achromatic vicinity area. More specifically, the chromaticity coordinates of the reflection spectra at each incidence angle are in the ranges of 0.31≦x≦0.34 and 0.28≦x≦0.34. Thus, the dielectric multilayer film of the second embodiment exhibits lower incident angle dependence than the dielectric multilayer film of the first embodiment. When the incident angle is varied from 0° to 30°, the changes in the x and y coordinates of the chromaticity coordinate (x, y) of the reflected light are both 0.1 or less, with the change in the x coordinate being 0.03 or less and the change in the y coordinate being 0.06 or less.

[0097] The first and second principal reflection peaks of the dielectric multilayer film have chromaticity coordinates on the short-wavelength and long-wavelength sides of the dotted line shown in Figure 13(b), resulting in the chromaticity coordinates of the reflected light being in the near-achromatic region. If this holds true for each incident angle, the dependence on the incident angle will be low.

[0098] From the reflection spectrum shown in Figure 12, it can be seen that both reflection peak p21 and reflection peak p22 have a full width at half maximum (FWHM) of 150 nm or less. The full width at half maximum (FWHM) of reflection peak p21 is 100 nm or less. A narrow full width at half maximum (FWHM) of the reflection peak means that when the color adjustment plate of the present invention is used in a solar cell module, the reflected light energy is suppressed, and as a result, the decrease in power generation efficiency can be suppressed, which is preferable.

[0099] Furthermore, from the viewpoint of suppressing a decrease in power generation efficiency, it is preferable that the reflectance of the "first main reflectance peak" and the "second main reflectance peak" be 70% or less, but in the dielectric multilayer film of the second embodiment, the reflectance of the "first main reflectance peak" and the "second main reflectance peak" is 40% or less.

[0100] (Color adjustment plate (third embodiment)) The color adjustment plate according to the third embodiment comprises a dielectric multilayer film that exhibits even lower incident angle dependence than the dielectric multilayer film of the second embodiment.

[0101] The optical properties of the dielectric multilayer film of the third embodiment having the above characteristics will be described. Figure 15(a) shows the chromaticity coordinate c on the xy chromaticity diagram for the reflected light when white light is perpendicularly incident on the dielectric multilayer film of the third embodiment. 30 (0.333, 0.327) is shown. Figure 15(b) shows the parameters of the dielectric multilayer model used in the simulation. Figure 16 shows the reflection spectrum when white light is perpendicularly incident on the dielectric multilayer of the third embodiment.

[0102] The reflection spectrum shown in Figure 16 has two reflection peaks p31 and p32 that satisfy the requirements (1-1) to (1-3) above. Specifically, reflection peaks p31 and p32 have peak wavelengths near 470 nm and 600 nm, respectively, within the wavelength range of 380 nm to 780 nm. Furthermore, reflection peaks p31 and p32 are the first primary reflection peak with a wavelength less than 520 nm and the second primary reflection peak with a wavelength of 520 nm or more, respectively, and the reflectance of reflection peak p32 is 20% or more of that of reflection peak p31, which exhibits the highest reflectance. Note that reflection peak p33 barely satisfies requirement (1-1) but does not satisfy requirement (1-3), and reflection peak p34 does not satisfy requirement (1-1). Thus, although the dielectric multilayer film of the third embodiment has different reflection characteristics from the dielectric multilayer film of the first embodiment, as can be seen in Figure 15(a), it exhibits a reflection spectrum with a chromaticity coordinate close to white light (achromatic) to the same extent as the dielectric multilayer film of the first embodiment.

[0103] <Incidence angle dependence> The dependence of reflected light on the incident angle of the dielectric multilayer film of the third embodiment will be explained. Figure 17 shows the chromaticity coordinates of the reflection spectra obtained by simulating the incident angle of white light on the dielectric multilayer film of the third embodiment, increasing the incident angle by 5° from perpendicular incidence, using optical thin film design software, and plotting them on the xy chromaticity diagram. In Figure 17, the chromaticity coordinates of the reflection spectra for each incident angle are all located in the achromatic vicinity. More specifically, the chromaticity coordinates of the reflection spectra for each incident angle are in the ranges of 0.31 ≤ x ≤ 0.34 and 0.32 ≤ x ≤ 0.34. Thus, the dielectric multilayer film of the third embodiment exhibits even lower incident angle dependence than the dielectric multilayer film of the second embodiment. When the incident angle is varied from 0° to 30°, the changes in the x and y coordinates of the chromaticity coordinate (x, y) of the reflected light are both 0.1 or less, with the change in the x coordinate being 0.03 or less and the change in the y coordinate being 0.02 or less.

[0104] From the reflection spectrum shown in Figure 16, it can be seen that both reflection peak p31 and reflection peak p32 have a full width at half maximum (FWHM) of 150 nm or less. The full width at half maximum (FWHM) of reflection peak p31 is 100 nm or less. A narrow full width at half maximum (FWHM) of the reflection peak means that when the color adjustment plate of the present invention is used in a solar cell module, the reflected light energy is suppressed, and as a result, the decrease in power generation efficiency can be suppressed, which is desirable.

[0105] Furthermore, from the viewpoint of suppressing a decrease in power generation efficiency, it is preferable that the reflectance of the "first main reflectance peak" and the "second main reflectance peak" be 70% or less, but in the dielectric multilayer film of the third embodiment, the reflectance of the "first main reflectance peak" and the "second main reflectance peak" is 30% or less.

[0106] (Color adjustment plate (fourth embodiment)) The color adjustment plate according to the fourth embodiment comprises a dielectric multilayer film having four reflection peaks that satisfy the requirements of (1-1) and (1-3) above.

[0107] The optical properties of the dielectric multilayer film of the fourth embodiment having the above characteristics will be described. Figure 18(a) shows the chromaticity coordinate c on the xy chromaticity diagram for the reflected light when white light is perpendicularly incident on the dielectric multilayer film of the fourth embodiment. 40 (0.311, 0.325) are shown. Figure 18(b) shows the parameters of the dielectric multilayer model used in the simulation. Figure 19 shows the reflection spectrum when white light is perpendicularly incident on the dielectric multilayer of the fourth embodiment.

[0108] The reflection spectrum shown in Figure 19 has four reflection peaks p41 to p44 that satisfy the requirements (1-1) to (1-3) above. Specifically, reflection peaks p41 to p44 have peak wavelengths near 440 nm, 490 nm, 560 nm, and 660 nm, respectively, within the wavelength range of 380 nm to 780 nm. Furthermore, reflection peaks p41 and p42 are first primary reflection peaks with wavelengths less than 520 nm, and reflection peaks p43 and p44 are second primary reflection peaks with wavelengths of 520 nm or more. Additionally, the reflectance of reflection peaks p42 to p44 is 20% or more of that of reflection peak p41, which exhibits the highest reflectance. Note that reflection peaks p45 and p46 do not satisfy the requirements of (1-1). Thus, although the dielectric multilayer film of the fourth embodiment has different reflection characteristics from the dielectric multilayer film of the first embodiment, as shown in Figure 18(a), it can be seen that it exhibits a reflection spectrum with a chromaticity coordinate close to white light (achromatic) to the same extent as the dielectric multilayer film of the first embodiment.

[0109] <Incidence angle dependence> The dependence of reflected light on the incident angle of the dielectric multilayer film of the fourth embodiment will be explained. Figure 20 shows the chromaticity coordinates of the reflection spectra obtained by simulating the incident angle of white light on the dielectric multilayer film of the fourth embodiment, increasing the incident angle by 5° from perpendicular incidence, using optical thin film design software, and plotting them on the xy chromaticity diagram. In Figure 20, the chromaticity coordinates of the reflection spectra for each incident angle are all located in the achromatic area. More specifically, the chromaticity coordinates of the reflection spectra for each incident angle are in the ranges of 0.31 ≤ x ≤ 0.33 and 0.32 ≤ x ≤ 0.35. Thus, the dielectric multilayer film of the fourth embodiment also exhibits low incident angle dependence, similar to the dielectric multilayer film of the third embodiment. When the incident angle is varied from 0° to 30°, the changes in the x and y coordinates of the chromaticity coordinate (x, y) of the reflected light are both 0.1 or less, with the change in the x coordinate being 0.02 or less and the change in the y coordinate being 0.03 or less.

[0110] From the reflection spectrum shown in Figure 19, it can be seen that the full width at half maximum (FWHM) of reflection peaks p41 to p44 is 100 nm or less. The full width at half maximum (FWHM) of reflection peaks p41 and p43 is 70 nm or less. A narrow full width at half maximum (FWHM) of the reflection peak means that when the color adjustment plate of the present invention is used in a solar cell module, the reflected light energy is suppressed, and as a result, the decrease in power generation efficiency can be suppressed, which is preferable.

[0111] Furthermore, from the viewpoint of suppressing a decrease in power generation efficiency, it is preferable that the reflectance of the "first main reflectance peak" and the "second main reflectance peak" be 70% or less, but in the dielectric multilayer film of the fourth embodiment, the reflectance of the "first main reflectance peak" and the "second main reflectance peak" is 55% or less.

[0112] (Color adjustment plate (5th embodiment)) The color adjustment plate according to the fifth embodiment comprises a dielectric multilayer film having a characteristic in which the full width at half maximum (FWHM) of at least one of the first principal reflection peak and the second principal reflection peak is narrower than that of any of the dielectric multilayer films according to the first to fourth embodiments.

[0113] The optical properties of the dielectric multilayer film of the fifth embodiment having the above characteristics will now be described. Figure 21 shows the chromaticity coordinate c on the xy chromaticity diagram for the reflected light when white light is perpendicularly incident on the dielectric multilayer film of the fifth embodiment. 50 (0.347, 0.331) are shown. The dielectric multilayer film of the fifth embodiment consists of 63 layers in which high refractive index layers of titanium dioxide (TiO2) and low refractive index layers of silicon dioxide (SiO2) are alternately stacked, with a total film thickness of 875.3 nm. Figure 21(b) shows the parameters of the dielectric multilayer film model used in the simulation. Figure 22 shows the reflection spectrum when white light is perpendicularly incident on the dielectric multilayer film of the fifth embodiment.

[0114] The reflection spectrum shown in Figure 22 has three reflection peaks p51 to p53 that satisfy the requirements (1-1) to (1-3) above. Specifically, reflection peaks p51 to p53 have peak wavelengths near 390 nm, 480 nm, and 590 nm, respectively, within the wavelength range of 380 nm to 780 nm. Furthermore, reflection peaks p51 and p52 are first primary reflection peaks with wavelengths less than 520 nm, and reflection peak p53 is a second primary reflection peak with wavelengths of 520 nm or more. Additionally, the reflectance of reflection peaks p52 and p53 is 20% or more of that of reflection peak p51, which exhibits the highest reflectance. Thus, although the dielectric multilayer film of the fifth embodiment has different reflection characteristics from the dielectric multilayer film of the first embodiment, as shown in Figure 21, it can be seen that it exhibits a reflection spectrum with a chromaticity coordinate close to white light (achromatic) to the same extent as the dielectric multilayer film of the first embodiment.

[0115] <Incidence angle dependence> The dependence of reflected light on the incident angle of the dielectric multilayer film of the fifth embodiment will be explained. Figure 23 shows the chromaticity coordinates of the reflection spectra obtained by simulating the incident angle of white light on the dielectric multilayer film of the fifth embodiment, increasing the incident angle by 5° from perpendicular incidence, using optical thin film design software, and plotting them on the xy chromaticity diagram. In Figure 23, the chromaticity coordinates of the reflection spectra for each incident angle are all located in the achromatic vicinity area. More specifically, the chromaticity coordinates of the reflection spectra for each incident angle are in the ranges of 0.30 ≤ x ≤ 0.35 and 0.31 ≤ x ≤ 0.34. The dielectric multilayer film of the fifth embodiment exhibits lower incident angle dependence than the dielectric multilayer film of the second embodiment. When the incident angle is varied from 0° to 30°, the changes in the x and y coordinates of the chromaticity coordinate (x, y) of the reflected light are both 0.1 or less, with the change in the x coordinate being 0.05 or less and the change in the y coordinate being 0.03 or less.

[0116] From the reflection spectrum shown in Figure 22, it can be seen that the full width at half maximum (FWHM) of all reflection peaks p51 to p53 is 50 nm or less. A narrow full width at half maximum (FWHM) of the reflection peak means that when the color adjustment plate of the present invention is used in a solar cell module, the reflected light energy is suppressed, and as a result, the decrease in power generation efficiency can be suppressed, which is desirable.

[0117] (Color adjustment plate (6th embodiment)) The color adjustment plate according to the sixth embodiment comprises a dielectric multilayer film consisting of eight or fewer layers, which is fewer than the dielectric multilayer film according to the first to fifth embodiments.

[0118] The optical properties of the dielectric multilayer film of the sixth embodiment having the above characteristics will now be described. Figure 24(a) shows the chromaticity coordinate c on the xy chromaticity diagram for the reflected light when white light is perpendicularly incident on the dielectric multilayer film of the sixth embodiment. 60 (0.324, 0.334) are shown. Figure 24(b) shows the parameters of the dielectric multilayer model used in the simulation, which consists of three layers with alternating layers of high refractive index titanium dioxide (TiO2) and low refractive index silicon dioxide (SiO2), with a total film thickness of 217.4 nm. Figure 25 shows the reflection spectrum when white light is perpendicularly incident on the dielectric multilayer film of the sixth embodiment.

[0119] The reflection spectrum shown in Figure 25 has two reflection peaks p61 and p62 that satisfy the requirements (1-1) to (1-3) above. In other words, reflection peaks p61 and p62 have peak wavelengths near 460 nm and 610 nm, respectively, within the wavelength range of 380 nm to 780 nm. Furthermore, reflection peak p61 is the first principal reflection peak with a wavelength less than 520 nm, and reflection peak p62 is the second principal reflection peak with a wavelength of 520 nm or more. Since the reflectances of reflection peaks p61 and p62 are approximately the same at around 7%, this indicates that the reflectance of one reflection peak is 20% or more of the reflectance of the other. Thus, although the dielectric multilayer film of the sixth embodiment has different reflection characteristics from the dielectric multilayer film of the first embodiment, as shown in Figure 24(a), it can be seen that it exhibits a reflection spectrum with a chromaticity coordinate close to white light (achromatic) to the same extent as the dielectric multilayer film of the first embodiment.

[0120] <Incidence angle dependence> The dependence of reflected light on the incident angle of the dielectric multilayer film of the sixth embodiment will be explained. Figure 26 shows the chromaticity coordinates of the reflection spectra obtained by simulating the incident angle of white light on the dielectric multilayer film of the sixth embodiment, increasing the incident angle by 5° from perpendicular incidence, using optical thin film design software, and plotting them on the xy chromaticity diagram. In Figure 26, the chromaticity coordinates of the reflection spectra for each incident angle are all located in the achromatic vicinity. More specifically, the chromaticity coordinates of the reflection spectra for each incident angle are in the ranges of 0.32 ≤ x ≤ 0.34 and 0.33 ≤ x ≤ 0.35. Thus, the dielectric multilayer film of the sixth embodiment also exhibits low incident angle dependence, similar to the dielectric multilayer film of the third embodiment. When the incident angle is varied from 0° to 30°, the changes in the x and y coordinates of the chromaticity coordinate (x, y) of the reflected light are both 0.1 or less, with the change in the x coordinate being 0.02 or less and the change in the y coordinate being 0.02 or less.

[0121] (Color adjustment plate (7th embodiment)) The color adjustment plate according to the seventh embodiment comprises a dielectric multilayer film in which the chromaticity coordinate of the reflected light for perpendicular incidence is in a range other than the achromatic area. That is, it comprises a dielectric multilayer film colored with a color other than whitish coloring.

[0122] The optical properties of the dielectric multilayer film of the seventh embodiment having the above characteristics will now be described. Figure 27(a) shows the chromaticity coordinate c on the xy chromaticity diagram for the reflected light when white light is perpendicularly incident on the dielectric multilayer film of the 7th embodiment. 70 The values ​​(0.506, 0.345) indicate an orange-ish color. Figure 27(b) shows the parameters of the dielectric multilayer model used in the simulation. Figure 28 shows the reflection spectrum when white light is perpendicularly incident on the dielectric multilayer of the 7th embodiment.

[0123] The reflection spectrum shown in Figure 28 has two reflection peaks p71 and p72 that satisfy the requirements (1-1) to (1-3) above. Specifically, reflection peaks p71 and p72 have peak wavelengths near 480 nm and 630 nm, respectively, within the wavelength range of 380 nm to 780 nm. Furthermore, reflection peak p71 is the first primary reflection peak with a wavelength less than 520 nm, and reflection peak p72 is the second primary reflection peak with a wavelength of 520 nm or more. Additionally, the reflectance of reflection peak p71 is 20% or more of that of reflection peak p72, which exhibits the highest reflectance. Note that reflection peaks p73 and p74 do not satisfy the requirements of (1-3), and reflection peak p75 does not satisfy the requirements of (1-1).

[0124] In the dielectric multilayer film of the seventh embodiment, the reflectance of the reflection peaks of the first principal reflection peak and the second principal reflection peak are significantly different, thereby allowing for a chromaticity coordinate c outside the achromatic area. 70 The system was designed to produce reflected light having (0.506, 0.345) values.

[0125] <Incidence angle dependence> The dependence of reflected light on the incident angle of the dielectric multilayer film of the seventh embodiment will be explained. Figure 29 shows the chromaticity coordinates of the reflection spectra obtained by simulating the incident angle of white light on the dielectric multilayer film of the 7th embodiment, increasing the incident angle by 5° from perpendicular, using optical thin film design software, and plotting them on the xy chromaticity diagram. In Figure 29, the chromaticity coordinates of the reflection spectra for each incident angle are all located in the orange area. More specifically, the chromaticity coordinates of the reflection spectra for each incident angle are in the ranges of 0.47 ≤ x ≤ 0.52 and 0.33 ≤ x ≤ 0.36. Thus, even in the case of the dielectric multilayer film of the seventh embodiment, which has chromaticity coordinates in the orange area under normal incidence, the chromaticity coordinates only change within a narrow range, and the dependence on the incidence angle is low.

[0126] (Color adjustment plate (8th embodiment)) The color adjustment plate according to the eighth embodiment comprises a dielectric multilayer film having four reflection peaks that satisfy the requirements of (1-1) and (1-3) above. It was confirmed that the change in the x and y coordinates in the chromaticity coordinate (x, y) of the reflected light was 0.1 or less when the incident angle dependence of the reflected light was varied over a wide range from 0° to 80°.

[0127] The optical properties of the dielectric multilayer film of the eighth embodiment having the above characteristics will be described. Figure 30(a) shows the chromaticity coordinate c on the xy chromaticity diagram for the reflected light when white light is perpendicularly incident on the dielectric multilayer film of the 8th embodiment. 80 (0.311, 0.325) are shown. Figure 30(b) shows the parameters of the dielectric multilayer model used in the simulation. Figure 31 shows the reflection spectrum when white light is perpendicularly incident on the dielectric multilayer of the 8th embodiment.

[0128] The reflection spectrum shown in Figure 31 has four reflection peaks p81 to p84 that satisfy the requirements (1-1) to (1-3) above. Specifically, reflection peaks p81 to p84 have peak wavelengths near 380nm, 430nm, 490nm, and 610nm, respectively, within the wavelength range of 380nm to 780nm. Furthermore, reflection peaks p81 to p83 are first primary reflection peaks with wavelengths less than 520nm, reflection peak p84 is a second primary reflection peak with wavelengths of 520nm or more, and the reflectance of reflection peaks p82 to p84 is 20% or more of that of reflection peak p81, which exhibits the highest reflectance. Thus, although the dielectric multilayer film of the fourth embodiment has different reflection characteristics from the dielectric multilayer film of the first embodiment, as can be seen in Figure 31(a), it exhibits a reflection spectrum with a chromaticity coordinate close to white light (achromatic) to the same extent as the dielectric multilayer film of the first embodiment.

[0129] <Incidence angle dependence> The dependence of reflected light on the incident angle of the dielectric multilayer film of the 8th embodiment will be explained. Figure 32 shows the chromaticity coordinates of the reflection spectra obtained from simulations using optical thin-film design software for the dielectric multilayer film of the 8th embodiment, when the incidence angle of white light was increased by 5° increments from perpendicular incidence. The chromaticity was observed over a wider range from 0° to 80° than in the previously shown embodiment. In Figure 32, the chromaticity coordinates of the reflection spectra for each incident angle are all located in the achromatic vicinity area. More specifically, the chromaticity coordinates of the reflection spectra for each incident angle are in the ranges of 0.31 ≤ x ≤ 0.33 and 0.33 ≤ x ≤ 0.36. Thus, the dielectric multilayer film exhibits low incident angle dependence, similar to that of the above-described embodiment. When the incident angle is varied over a wider range from 0° to 80°, the changes in the x and y coordinates of the reflected light's chromaticity coordinate (x, y) are both 0.1 or less, with the change in the x coordinate being 0.02 or less and the change in the y coordinate being 0.03 or less.

[0130] (Color adjustment plate (9th embodiment)) Figure 33 is a schematic cross-sectional view of the color adjustment plate according to the ninth embodiment. The color adjustment plate 20 shown in Figure 33 comprises a two-dimensional transparent substrate 21 (21A, 21B, 21C) and a dielectric multilayer film 22 on the entire outer surface of the transparent substrate 21 (21a, 21b, 21c, 21d), in which high refractive index layers 22a and low refractive index layers 22b are alternately laminated. Figure 33 shows three color adjustment plates 20. Furthermore, the dielectric multilayer film 22 is configured to satisfy the following conditions (1-1) to (1-3); (1-1) When white light is incident from a vertical direction, the reflected light reflected in the same direction as the vertical direction exhibits spectral reflectance characteristics having multiple reflection peaks in the wavelength range of 380 nm to 780 nm. (1-2) The plurality of reflection peaks each include at least one first principal reflection peak with a wavelength of less than 520 nm and one second principal reflection peak with a wavelength of 520 nm or more. (1-3) The plurality of reflection peaks exhibit a reflectance of 20% or more relative to the reflection peak showing the highest reflectance among the reflection peaks in the wavelength range.

[0131] Examples of the two-dimensional transparent substrates 21 include natural mica, artificial mica, glass, and inorganic single crystals. Having two dimensions means that the thickness is small compared to the size when viewed in plan view, for example, it means that it is 1 / 10 or less.

[0132] As described later, in this embodiment, the color adjustment plate forms a dielectric multilayer film on a transparent substrate by a liquid-phase method such as the sol-gel method, so the dielectric multilayer film is formed over the entire outer surface of the transparent substrate 21.

[0133] The high refractive index layer 22a and the low refractive index layer 22b can be layers composed of a large number of crystal particles smaller than the wavelength of visible light. Layers composed of crystal particles smaller than the wavelength of visible light act optically as films. As crystal particles, the crystal particles of the materials for the high refractive index layer 2a and the low refractive index layer 2b described above can be used.

[0134] The optical properties of the dielectric multilayer film of the ninth embodiment having the above characteristics will now be described. Figure 34(a) shows the chromaticity coordinate c on the xy chromaticity diagram for the reflected light when white light is perpendicularly incident on the dielectric multilayer film of the ninth embodiment. 80 The values ​​shown are (0.329, 0.322). Figure 34(b) shows the parameters of the dielectric multilayer model used in the simulation. Figure 35 shows the reflection spectrum when white light is perpendicularly incident on the dielectric multilayer of the ninth embodiment. In this model, mica is used as the transparent substrate, and PMMA (polymethyl methacrylate resin) for attaching color adjustment plates to items such as solar cells is formed on the dielectric multilayer. The simulation results are only for the top surface of the mica, but similar results were obtained for the bottom surface.

[0135] The reflectance spectrum shown in Figure 35 has two reflectance peaks, p91 ​​and p92, that satisfy the requirements (1-1) to (1-3) above. Specifically, the reflection peaks p91 and p92 have peak wavelengths near 380 nm and near 600 nm, respectively, within the wavelength range of 380 nm to 780 nm. Furthermore, reflection peak p91 is the first principal reflection peak with a wavelength less than 520 nm, and reflection peak p92 is the second principal reflection peak with a wavelength of 520 nm or more. The reflectance of reflection peak p92 is 20% or more of that of reflection peak p91, which exhibits the maximum reflectance. Thus, although the dielectric multilayer film of the ninth embodiment has different reflection characteristics from the dielectric multilayer film of the first embodiment, as can be seen in Figure 34(a), it exhibits a reflection spectrum with a chromaticity coordinate close to white light (achromatic) to the same extent as the dielectric multilayer film of the first embodiment.

[0136] <Incidence angle dependence> The dependence of reflected light on the incident angle of the dielectric multilayer film of the ninth embodiment will be explained. Figure 36 shows the chromaticity coordinates of the reflection spectra obtained by simulating the incident angle of white light on the dielectric multilayer film of the ninth embodiment, increasing the incident angle by 5° from perpendicular, using optical thin film design software, and plotting them on the xy chromaticity diagram. In Figure 36, the chromaticity coordinates of the reflection spectra for each incident angle are all located in the achromatic area. More specifically, the chromaticity coordinates of the reflection spectra for each incident angle are in the ranges of 0.32 ≤ x ≤ 0.33 and 0.31 ≤ x ≤ 0.34. Thus, the dielectric multilayer film of the ninth embodiment also exhibits low incident angle dependence, similar to the dielectric multilayer film of the above embodiments. When the incident angle is varied from 0° to 30°, the changes in the x and y coordinates of the chromaticity coordinate (x, y) of the reflected light are both 0.1 or less, with the change in the x coordinate being 0.01 or less and the change in the y coordinate being 0.03 or less. As will be described later, in this embodiment, a number of color adjustment plates are attached to a target item such as a solar cell by coating or the like. However, even if the color adjustment plates are tilted relative to each other, there is almost no effect on the color because the incident angle dependence on the reflection spectrum is low.

[0137] (Color adjustment plate (10th embodiment)) The color adjustment plate according to the 10th embodiment, like the color adjustment plate according to the 9th embodiment, comprises a plurality of two-dimensional transparent substrates and a dielectric multilayer film formed on the entire outer surface of the transparent substrates, in which high refractive index layers and low refractive index layers are alternately laminated.

[0138] The optical properties of the dielectric multilayer film of the 10th embodiment having the above characteristics will be described. Figure 37(a) shows the chromaticity coordinate c on the xy chromaticity diagram for the reflected light when white light is perpendicularly incident on the dielectric multilayer film of the 10th embodiment. 90 The values ​​shown are (0.325, 0.329). Figure 37(b) shows the parameters of the dielectric multilayer model used in the simulation. Figure 38 shows the reflection spectrum when white light is perpendicularly incident on the dielectric multilayer film of the 10th embodiment. Mica was used as the transparent substrate, and the simulation was performed using a model in which PMMA (polymethyl methacrylate resin), used for attaching color adjustment plates to items such as solar cells, was formed on the dielectric multilayer film.

[0139] The reflectance spectrum shown in Figure 38 has two reflectance peaks, p101 and p102, that satisfy the requirements of (1-1) to (1-3) above. Specifically, the reflection peaks p101 and p102 have peak wavelengths near 380 nm and near 590 nm, respectively, within the wavelength range of 380 nm to 780 nm. Furthermore, reflection peak p91 is the first principal reflection peak with a wavelength less than 520 nm, reflection peak p92 is the second principal reflection peak with a wavelength of 520 nm or more, and the reflectance of reflection peak p102 is 20% or more of that of reflection peak p101, which exhibits the highest reflectance. Thus, although the dielectric multilayer film of the ninth embodiment has different reflection characteristics from the dielectric multilayer film of the first embodiment, as can be seen in Figure 37(a), it exhibits a reflection spectrum with a chromaticity coordinate close to white light (achromatic) to the same extent as the dielectric multilayer film of the first embodiment.

[0140] (How to use color adjustment boards) Figures 39 and 40 show examples of how to use the color adjustment plate according to the present invention.

[0141] As shown in Figure 39(b), the color adjustment plate of the present invention (Figure 39(a)) can be used by appropriately arranging other layers, such as a sealing material, on the dielectric multilayer film.

[0142] The example shown in Figure 40 illustrates its use in a solar cell module, but it can be used in other products if used in a similar manner. In Figures 40(a) to (g), the symbols 100A, 100B, 100C, 100D, 100E, 100F, and 100G represent solar cell modules, the symbols 10A, 10B, 10C, 10D, 10E, 10F, and 10G represent color adjustment plates, the symbols 11A, 11B, 11C, 11D, 11E, 11F, and 11G represent solar cells, the symbols 1A, 1B, 1C, 1D, 1E, 1F, and 1G represent substrates, and the symbols 2A, 2B, 2C, 2D, 2E, 2F, and 2G represent dielectric multilayer films. Figure 40(a) shows an example in which the color adjustment plate of the present invention is provided on the light-receiving surface side of a solar cell module, with the dielectric multilayer film facing the solar cell side; (b) shows the opposite of (a), with the substrate side facing the solar cell side; (c) shows an example in which a back sheet is provided on the back side of the solar cell module; (d) shows an example in which the color adjustment plate of the present invention is provided on the light-receiving surface side of a solar cell module, with the solar cell being placed in a sealed space containing a gas such as air; (e) to (g) show examples in which the substrate surface has irregularities; (e) shows the color adjustment plate of the present invention provided on the light-receiving surface side of a solar cell module. (f) is an example in which the dielectric multilayer film is arranged facing the solar cell side and the surface of the substrate facing the atmosphere has irregularities; (g) is an example in which the color adjustment plate of the present invention is provided on the light-receiving surface side of the solar cell module, the substrate is arranged facing the solar cell side and the surface of the substrate facing the atmosphere has irregularities and the dielectric multilayer film is formed on the surface having irregularities; (g) is an example in which the color adjustment plate of the present invention is provided on the light-receiving surface side of the solar cell module, the dielectric multilayer film is arranged facing the solar cell side and the surface of the substrate facing the solar cell side has irregularities and the dielectric multilayer film is formed on the surface having irregularities.

[0143] <Color adjustment plate using a substrate with a diffuse reflective surface> Figures 41(a) to (c) are schematic cross-sectional diagrams of a color adjustment plate according to the present invention, in which either the film-forming surface or the non-film-forming surface of the substrate is a diffuse reflective surface. The graph shown in Figure 41 shows the configuration in which a diffuse reflective surface is formed by sandblasting using abrasive grains of #600, #400, and #220 (Fuji Manufacturing Co., Ltd., Fuji Random A), and when a solar cell is placed below the color adjustment plate, white light is incident perpendicularly from above (a) to (c) (arrows in the figure), and the whiteness (L) of the reflected light * This shows the results of measuring the whiteness (L). Fuji Random A is an abrasive material made of brown fused alumina, which is a type of alumina-silicon carbide. In the graph, the horizontal axis #600, #400, and #220 represent the grit size of the abrasive grains, and the vertical axis represents the whiteness (L). *The values ​​are shown. The abrasive grain sizes are as follows: #600 has an average particle diameter of 20.0 μm ± 1.5 μm and a maximum particle diameter of 53.0 μm or less; #400 has an average particle diameter of 25.0 μm ± 2.0 μm and a maximum particle diameter of 63.0 μm or less; and #220 has a central particle size of 75 to 45 μm.

[0144] In Figures 41(a) to (c), substrate 1 (1a, 1b, 1c, 1d) is BK7 (borosilicate crown glass), and dielectric multilayer film 2 (2a, 2b, 2c) is a multilayer film consisting of 12 layers, in order from the substrate side: 1st layer (TiO2, 15.1nm), 2nd layer (SiO2, 37.1nm), 3rd layer (TiO2, 15.3nm), 4th layer (SiO2, 44.1nm), 5th layer (TiO2, 84.9nm), 6th layer (SiO2, 21.4nm), 7th layer (TiO2, 97.7nm), 8th layer (SiO2, 22.7nm), 9th layer (TiO2, 22.5nm), 10th layer (SiO2, 22.4nm), 11th layer (TiO2, 10nm), and 12th layer (SiO2, 103.8nm). The color adjustment plate shown in Figure 41(a) has a dielectric multilayer film 2a formed on the flat surface of the substrate 1a that is on the side of the white light incident surface and has not been sandblasted, and the diffuse reflective surface 1aa of the substrate 1a is positioned on the solar cell side. The color adjustment plate in Figure 41(b) (corresponding to Figure 40(g)) has a dielectric multilayer film 2b formed on the diffuse reflective surface 1bb on the solar cell side of the substrate 1b, and the surface on which white light is incident is a flat surface that has not been sandblasted. The color adjustment plate in Figure 41(c) (corresponding to Figure 40(e)) has a dielectric multilayer film 2b formed on the solar cell side of the substrate 1b, on a flat surface that has not been sandblasted, and the incident surface of white light is a diffuse reflection surface 1cc. Figure 41(d) shows, for reference, a configuration consisting only of a substrate 1d without a dielectric multilayer film, where white light is incident on a flat surface that has not been sandblasted, and the solar cell side has a diffuse reflecting surface 1dd.

[0145] The following findings were obtained from the results shown in Figure 41. (a) to (c) all use abrasive grains in the order of #220, #400, and #600 L *The value is high. In other words, when sandblasting with these three types of abrasive grains to form a diffuse reflection surface, using coarser abrasive grains (smaller grit abrasive grains) is better. * The value is high. This indicates that scattered light can be adjusted by the degree of the uneven structure of the diffuse reflecting surface, and the size of the uneven structure of the obtained diffuse reflecting surface is L in the order of #220, #400, and #600 abrasive grains. * This indicates that it was suitable for increasing the value. When using #220 and #400 abrasive grains, the color adjustment plate (c) (corresponding to Figure 40(e)) in which the dielectric multilayer film placed on the flat surface of the substrate is positioned on the solar cell side and the diffuse reflective surface is positioned on the side where light is incident is the most L * The value is high.

[0146] Figure 42 shows the results of measuring the reduction rate ΔJsc(%) of the short-circuit current (current flowing when the external voltage applied to the solar cell is 0V) of a solar cell module when the diffuse reflective surface of a color adjustment plate with the configuration shown in Figures 41(a) to (c) is formed by sandblasting with abrasive grains of #600, #400, and #220, respectively. For reference, the results of measuring the reduction rate ΔJsc(%) of the short-circuit current of a solar cell module when a substrate with the configuration shown in Figure 41(d) is used instead of the color adjustment plate are also shown. ΔJsc(%) is an index for evaluating solar cell efficiency.

[0147] The following findings were obtained from the results shown in Figure 42. In all of (a) to (c), the reduction rate of the short-circuit current ΔJsc is smallest in the order of #600, #400, and #220 abrasive grains. In other words, when a diffuse reflective surface is formed by sandblasting with these three types of abrasive grains, using finer abrasive grains (higher grit abrasive grains) suppresses ΔJsc (i.e., the decrease in solar cell efficiency is suppressed). This shows that the reduction rate of the short-circuit current ΔJsc can be adjusted by the degree of the uneven structure of the diffuse reflective surface, and that the size of the uneven structure of the resulting diffuse reflective surface is suitable for suppressing the reduction rate of the short-circuit current ΔJsc in the order of #600, #400, and #220 abrasive grains. In all cases, the color adjustment plate (c) (corresponding to Figure 40(e)) in which the dielectric multilayer film arranged on the flat surface of the substrate is positioned on the solar cell side and the diffuse reflective surface is positioned on the side where light is incident, suppresses the short-circuit current reduction rate ΔJsc the most (i.e., the decrease in solar cell efficiency is suppressed).

[0148] Based on the results shown in Figures 41 and 42, among the color adjustment plates with configurations shown in Figures 41(a) to (c), the color adjustment plate in (c) (corresponding to Figure 40(e)), in which the dielectric multilayer film placed on the flat surface of the substrate is positioned on the solar cell side and the diffuse reflective surface is positioned on the side where light is incident, has a high L * It was found that this value was achieved and that it most effectively suppressed the reduction rate of short-circuit current ΔJsc.

[0149] Figures 43(a) to (c) show optical microscope images of the diffuse reflection surface of glass substrates sandblasted with abrasive grains of #600, #400, and #220, respectively. Figure 44 shows the arithmetic mean roughness Ra, maximum height Ry, and root mean square height Rq for each of the XX lines in Figures 43(a) to (c).

[0150] Based on the roughness of the diffuse reflecting surface shown in Figure 44 and the results shown in Figures 41 and 42, the following findings can be obtained. Using the root mean square height Rq as a representative of roughness, a Rq of approximately 1.2 μm to 1.8 μm indicates high whiteness (L * You can obtain the value. Furthermore, if Rq is around 0.4 μm to 1.3 μm, the rate of decrease in short-circuit current ΔJsc can be suppressed (i.e., the decrease in solar cell efficiency can be suppressed). To enhance whiteness while prioritizing the efficiency of the solar cell, the roughness Rq of the diffuse reflecting surface is preferably 0.4 μm to 1.3 μm.

[0151] (Solar cell module (first embodiment)) The solar cell module according to this embodiment comprises a plurality of solar cells and a color adjustment plate disposed on the light-receiving surface side of the plurality of solar cells. The color adjustment plate has a substrate and a dielectric multilayer film formed on the substrate, in which high refractive index layers and low refractive index layers are alternately stacked. The dielectric multilayer film is configured to satisfy the above (1-1) to (1-3), (1-5), and (1-6).

[0152] Figure 45 is a schematic cross-sectional view of a part of a solar cell module to which the color adjustment plate of the present invention is applied. The solar cell module 100 shown in Figure 45 comprises a solar cell 111, a color adjustment plate 10A provided on the light-receiving surface side of the solar cell 111, a second protective member 112 provided on the back side of the solar cell 111, and a sealing material 114 provided between the first protective member 11 and the second protective member 112 to seal the solar cell 111. The sealing material 114 includes a sealing material 114a disposed between the solar cell 111 and the first protective member 11, and a sealing material 114b disposed between the solar cell 111 and the second protective member 112. In this embodiment, a plurality of solar cells 111 are arranged between each protective member, and wiring material 115 is provided to connect the solar cells 111 to each other. The color adjustment plate 10A shown in Figure 45 consists of a first protective member (corresponding to the substrate 1) 11 and a dielectric multilayer film 12 formed on the first protective member 11, in which high refractive index layers and low refractive index layers are alternately stacked. Any known type of solar cell can be used as the solar cell 111. For example, in terms of electrode arrangement, either a double-sided electrode solar cell or a back-side electrode solar cell can be used. Furthermore, there are no particular restrictions in classifying solar cells into three types: silicon-based, compound semiconductor-based, and organic-based, and any type of solar cell can be used.

[0153] The first protective member 11 can be made of a light-transmitting material such as a glass substrate, a resin substrate, or a resin film. The second protective member 112 may be made of the same transparent material as the first protective member 11, or it may be made of an opaque material.

[0154] The sealing material 114 serves to prevent moisture and other substances from coming into contact with the solar cell 111. The resin constituting the sealing material 114 is preferably one that adheres well to each protective member and the solar cell 111, and is resistant to moisture permeability. The wiring material 115 is attached to the electrodes of the solar cell 111, for example, by adhesive.

[0155] (Solar cell module (second embodiment)) The solar cell module according to this embodiment comprises a plurality of solar cells and a color adjustment plate disposed on the light-receiving surface side of the plurality of solar cells. The color adjustment plate comprises a plurality of two-dimensional transparent substrates and a dielectric multilayer film formed on the entire outer surface of the transparent substrates, in which high refractive index layers and low refractive index layers are alternately stacked. The dielectric multilayer film is configured to satisfy the following (1-1) to (1-3), (1-5), and (1-6).

[0156] (Solar cell module (third embodiment)) The solar cell module according to this embodiment comprises a plurality of solar cells and a color adjustment plate disposed on the light-receiving side of the plurality of solar cells. The color adjustment plate has a substrate and an inorganic pigment-containing layer formed on at least one of the front and back surfaces of the substrate, and one of the surfaces of the substrate, which is either a film-forming surface on which the inorganic pigment-containing layer is formed and a non-film-forming surface on which the inorganic pigment-containing layer is not formed, is formed as a diffuse reflecting surface having an uneven structure, or is a diffuse plate.

[0157] For example, pearl pigments can be used as the inorganic pigment contained in the inorganic pigment-containing layer. Pearl pigments are pigments in which the surface of flake-like particles (for example, particles with a maximum diameter of 2 to 100 μm and a thickness of 0.01 to 10 μm) is coated with a metal or its oxide. Examples of flake-like particles include natural mica, artificial mica, glass, and inorganic single crystals. Examples of metals or their oxides that coat the surface of the flake-like particles include titanium dioxide, iron oxide, and silver. Examples of commercially available pearl pigments include TWINCLEPEARL (product name, manufactured by Nippon Koken Kogyo Co., Ltd.). For example, TWINCLEPEARL SXD (average particle size: 5-60 μm) can be used.

[0158] The inorganic pigment-containing layer can be formed by coating, vapor deposition, or other methods. For example, when forming an inorganic pigment-containing layer by coating using TWINCLEPEARL SXD (average particle size: 5-60 μm) as the mica pearl pigment, it is preferable to set the concentration to approximately 0.125% by weight. The concentration is determined by the reduction rate of the short-circuit current ΔJsc (%) and the whiteness (L). * From a value perspective, it is preferable not to exceed 0.5% by weight, for example, it can be between 0.1% and 0.5% by weight.

[0159] The color adjustment plate shown in Figure 41(c), where the symbol 2c in Figure 41(c) represents an inorganic pigment-containing layer formed by coating mica pearl pigment (TWINCLEPEARL SXD) at a concentration of 0.125 wt%, was used to investigate the relationship between the surface roughness of the diffuse reflective surface (corresponding to the symbol 1cc in Figure 41(c)) and the reduction rate ΔJsc (%) of the short-circuit current of the solar cell module. The results are shown in Figure 46. White light was incident on the diffuse reflective surface at an incident light angle of 45° (with the direction perpendicular to the substrate surface being 0°). Surface roughness was evaluated using the root mean square height Rq [μm], and the "contact type (stylus type)" evaluation method in accordance with ISO 25178. The measurement was performed using a Dektak (Bruker) stylus-type surface roughness meter. The diffuse reflecting surface was created by sandblasting. For comparison, ΔJsc was also evaluated for a surface that had not been sandblasted (with the same configuration except for the absence of sandblasting). In Figure 46, incident light from the diffuse reflecting surface is labeled as textured surface incidence, and for comparison, incident light on a surface that has not been sandblasted and does not have texture is labeled as flat plate incidence.

[0160] Figure 46 shows that as the surface roughness of the diffuse reflecting surface increases to about 3 μm, ΔJsc also increases (in other words, the solar cell efficiency decreases). To keep ΔJsc within 25%, it is preferable to set the surface roughness Rq of the diffuse reflecting surface to 2.0 μm or less. Furthermore, to keep ΔJsc within 20%, it is preferable to set the surface roughness Rq of the diffuse reflecting surface to 1.3 μm or less.

[0161] Figure 47 shows the surface roughness of the diffuse reflection surface and the whiteness (L) of the color adjustment plate, using the same color adjustment plate used to obtain Figure 46. White light was incident on the diffuse reflection surface at an incident light angle of 45° (0° being the direction perpendicular to the substrate surface), and observed at 0°. * The relationship with the value (L) will be investigated and the results will be shown. For comparison, the whiteness (L) of samples that have not been sandblasted (with the same configuration except for the absence of sandblasting) will also be investigated. * The value was evaluated. In Figure 47, the planar incidence is the case without sandblasting.

[0162] From Figure 47, as the surface roughness increases up to approximately 3 μm, the whiteness (L) of the color adjustment plate decreases. * It can be seen that the value increases. Whiteness (L * To make the value (L) 25 or higher, it is preferable to make the surface roughness Rq 0.1 μm or higher. * To achieve a value of 35 or higher, it is preferable to set the surface roughness Rq to 1.5 μm or higher.

[0163] From the results shown in Figures 46 and 47, the following findings can be obtained regarding the solar cell module according to the third embodiment. In a color adjustment plate having a diffuse reflective surface, ΔJsc is kept within 25%, and the whiteness (L) is maintained. * To achieve a value of 25 or higher, it is preferable to set the surface roughness Rq of the diffuse reflecting surface to 0.1 μm or more and 2.0 μm or less. In a color adjustment plate having a diffuse reflective surface, ΔJsc is kept within 25%, and the whiteness (L) is maintained. * To achieve a value of 30 or more, it is preferable to set the surface roughness Rq to 0.7 μm or more and 2.0 μm or less. In a color adjustment plate having a diffuse reflective surface, ΔJsc is kept within 25%, and the whiteness (L) is maintained. * To achieve a value of 35 or higher, it is preferable to set the surface roughness Rq to 1.5 μm or more and 2.0 μm or less. In a color adjustment plate having a diffuse reflective surface, ΔJsc is kept within 20%, and the whiteness (L) is maintained. * To achieve a value of 25 or higher, it is preferable to set the surface roughness Rq to 0.1 μm or more and 1.3 μm or less. In a color adjustment plate having a diffuse reflective surface, ΔJsc is kept within 20%, and the whiteness (L) is maintained. * To achieve a value of 30 or more, it is preferable to set the surface roughness Rq to 0.7 μm or more and 1.3 μm or less.

[0164] Whether the layer having the color adjustment function in the color adjustment plate is an inorganic pigment-containing layer, or a dielectric multilayer film in which high refractive index layers and low refractive index layers are alternately stacked, when using a substrate with a diffuse reflective surface, depending on whether solar cell efficiency or whiteness is prioritized, the surface roughness Rq of the diffuse reflective surface may preferably be 0.1 μm to 2.0 μm, 0.1 μm or more and 1.3 μm or less, 0.7 μm or more and 1.3 μm or less, 0.3 μm or more and 1.3 μm or less, 0.7 μm or more and 2.0 μm or less, or 1.5 μm or more and 2.0 μm or less.

[0165] (Manufacturing method for color adjustment plates) The method for manufacturing a color adjustment plate according to the present invention is a method for manufacturing a color adjustment plate according to the present invention, comprising a dielectric multilayer determination step in which at least one parameter of the dielectric multilayer film, such as the material of the high refractive index layer and the low refractive index layer, the thickness of each layer, and the number of layers, is determined by optical thin film design simulation.

[0166] (Film forming method) The present invention relates to a film deposition method for forming a dielectric multilayer film on a substrate or on the entire outer surface of a transparent substrate, wherein high refractive index layers and low refractive index layers are alternately stacked, and at least one parameter of the material of the high refractive index layer and the low refractive index layer, the thickness of each layer, and the number of layers is determined by optical thin film design simulation so that the dielectric multilayer film satisfies at least the following (1-1) to (1-3); (1-1) When white light is incident from a vertical direction, the reflected light reflected in the same direction as the vertical direction exhibits spectral reflectance characteristics having multiple reflection peaks in the wavelength range of 380 nm to 780 nm. (1-2) The plurality of reflection peaks each include at least one first principal reflection peak with a wavelength of less than 520 nm and one second principal reflection peak with a wavelength of 520 nm or more. (1-3) The plurality of reflection peaks exhibit a reflectance of 20% or more relative to the reflection peak showing the highest reflectance among the reflection peaks in the wavelength range.

[0167] For the color adjustment plates according to the first to eighth embodiments, known dry thin-film methods such as vapor deposition and sputtering can be used when forming a dielectric multilayer film on the substrate. Alternatively, known wet thin-film methods may be used.

[0168] Furthermore, the manufacturing of the color adjustment plates according to the 9th to 10th embodiments may include a step for adjusting the size of a two-dimensional transparent substrate such as mica. For example, mica raw material may be crushed (e.g., wet crushing), classified, and particle size adjusted to obtain a mica substrate with a desired particle size distribution.

[0169] Furthermore, for the color adjustment plates according to the 9th to 10th embodiments, when forming a dielectric multilayer film over the entire outer surface of the transparent substrate, known wet thin-film formation methods such as the titanyl sulfate method, titanium tetrachloride method, and sol-gel method can be used. For example, the following chemical reactions can be used for forming the TiO2 layer, SiO2 layer, and SnO2 layer. These layers may be subjected to crystallization processes such as drying and firing as appropriate. ·TiOSO4+ 3H2O → TiO2·2H2O + H2SO4 ·Ti(OCH2CH3)4+ 2H2O → TiO2+ 4CH3CH2OH ·Si(OCH2CH3)4+ 2H2O → SiO2+ 4CH3CH2OH ·Sn(OCH2CH3)4+ 2H2O → SnO2+ 4CH3CH2OH Furthermore, a color adjustment plate, for example, in which a dielectric multilayer film is deposited on multiple transparent substrates having two-dimensional properties such as mica, can be attached to a target article such as a solar cell using acrylic resin or the like (reference numeral 30 in Figure 48). More specifically, for example, a solar cell module can be manufactured by mixing the color adjustment plate with a clear paint such as acrylic resin, and then coating and drying it. For coating, a bar coater, doctor blade, spray gun, applicator, etc., can be used. The color adjustment plate 20, which has multiple transparent substrates having two-dimensional properties such as mica, is fixed parallel to the glass substrate when the solvent in the clear paint evaporates and solidifies, and as shown in Figure 48, it is bonded to the target article (e.g., solar cell) 121 with the two-dimensional surfaces parallel to each other, thereby manufacturing a solar cell module 200. Pigment coating techniques can be applied as appropriate during fixing. Moreover, even if the two-dimensional surface is tilted at about 30°, as mentioned above, there is almost no effect on the color due to the low incident angle dependence of the reflection spectrum. The size (in the two-dimensional plane direction) of transparent substrates such as mica is not specifically defined, as they are usually used after being peeled and crushed. However, they are typically irregular in shape, ranging from a few micrometers to several hundred micrometers, with a thickness of a few nanometers to a few micrometers. Furthermore, by attaching the color adjustment plate prepared in this manner to a transparent substrate (such as glass), it can be used in a structure exactly the same as that shown in Figure 40.

[0170] As an example of the coating described above, the acrylic resin may be thinned with butyl acetate or the like to make it easier to apply. That is, for example, the acrylic resin may be thinned so that it becomes about 70% after drying. Alternatively, the initial film thickness with a spray gun or applicator may be set to about 200 μm, so that about 30% of the resin solids remain after drying shrinkage, and the mica is aligned parallel to the glass substrate. Furthermore, it is preferable to perform a surface treatment on the glass substrate surface, such as polarity treatment, so that the mica pigment and acrylic resin adhere firmly and uniformly.

[0171] (Film forming equipment) The film deposition apparatus according to the present invention is a film deposition apparatus for forming a dielectric multilayer film in which high refractive index layers and low refractive index layers are alternately stacked on a substrate or on the entire outer surface of a transparent substrate, and comprises optical parameter determination means for determining at least one parameter of the material of the high refractive index layer and the low refractive index layer, the thickness of each layer, and the number of layers by optical thin film design simulation such that the dielectric multilayer film satisfies at least the following (1-1) to (1-3); (1-1) When white light is incident from a vertical direction, the reflected light reflected in the same direction as the vertical direction exhibits spectral reflectance characteristics having multiple reflection peaks in the wavelength range of 380 nm to 780 nm. (1-2) The plurality of reflection peaks each include at least one first principal reflection peak with a wavelength of less than 520 nm and one second principal reflection peak with a wavelength of 520 nm or more. (1-3) The plurality of reflection peaks exhibit a reflectance of 20% or more relative to the reflection peak showing the highest reflectance among the reflection peaks in the wavelength range. [Explanation of Symbols]

[0172] 1 circuit board 2,22 Dielectric Multilayer Film 2a, 22a High refractive index layer 2b, 22b Low refractive index layer 10, 10A, 20 color adjustment board 21 Transparent substrate 30 Color adjustment plate fixing agent 100, 200 solar modules 111, 121 Solar cells

Claims

1. a transparent substrate having two-dimensionality; a dielectric multilayer film formed on the entire outer surface of the transparent substrate, in which high refractive index layers and low refractive index layers are alternately stacked; The dielectric multilayer film is a color adjustment plate configured to satisfy the following (1-1) to (1-3): (1-1) When white light is incident from a vertical direction, the reflected light reflected in the same direction as the vertical direction exhibits spectral reflectance characteristics having multiple reflection peaks in a wavelength range of 380 nm to 780 nm, (1-2) The plurality of reflection peaks include at least one first main reflection peak at a wavelength less than 520 nm and one second main reflection peak at a wavelength equal to or greater than 520 nm; (1-3) The plurality of reflection peaks exhibit a reflectance of 20% or more relative to the reflection peak exhibiting the maximum reflectance among the reflection peaks in the wavelength range.

2. The color adjustment plate of claim 1, wherein one of the film-forming surface of the transparent substrate on which the dielectric multilayer film is formed and the non-film-forming surface on which the dielectric multilayer film is not formed is formed as a diffuse reflection surface having an uneven structure.

3. 3. The color adjustment board according to claim 2, wherein the non-film-formed surface is formed as a diffuse reflection surface.

4. 3. The color adjustment plate according to claim 1, wherein the size of the transparent substrate is 1 μm to 1000 μm.

5. 3. The color adjustment plate according to claim 1, wherein the transparent substrate is one selected from the group consisting of natural mica, artificial mica, glass, and inorganic single crystals.

6. The color-adjusting plate of claim 1 , wherein the transparent substrate is a diffuser plate.

7. The color adjustment plate according to claim 1 , wherein the plurality of reflection peaks are two reflection peaks.

8. The color adjustment plate according to claim 1 , wherein the plurality of reflection peaks are three reflection peaks.

9. The color adjustment plate according to claim 1 or 2, wherein the plurality of reflection peaks are four reflection peaks.

10. The color adjustment plate according to claim 1 or 2, wherein the dielectric multilayer film is further configured to satisfy the following (1-4): (1-4) When the angle of incidence from the perpendicular direction is changed from 0° to 30°, the change in the x-coordinate and the y-coordinate of the chromaticity coordinate (x, y) of the reflected light on the CIE-xy chromaticity diagram is both 0.1 or less.

11. The color adjustment plate according to claim 1 or 2, wherein the dielectric multilayer film is further configured to satisfy the following (1-5): (1-5) At least one of the first and second main reflection peaks has a full width at half maximum (FWHM) of 200 nm or less.

12. The color adjustment plate according to claim 1 or 2, wherein the dielectric multilayer film is further configured to satisfy the following (1-6): (1-6) The reflectances of the first and second main reflection peaks are both 70% or less.

13. The color adjustment plate according to claim 1 or 2, wherein the dielectric multilayer film is further configured to satisfy the following (1-7): (1-7) A color adjustment plate in which the chromaticity coordinates (x, y) of the reflected light on the CIE-xy chromaticity diagram are in the range of 0.25≦x≦0.4 and 0.25≦y≦0.

4.

14. The color adjustment plate according to claim 1 or 2, wherein the dielectric multilayer film is further configured to satisfy the following (1-8): (1-8) A color adjustment plate in which the chromaticity coordinates (x, y) of the reflected light on the CIE-xy chromaticity diagram are outside the range surrounded by 0.25≦x≦0.4 and 0.25≦y≦0.

4.

15. A plurality of solar cells; a color adjustment plate disposed on the light receiving surface side of the plurality of solar cells, the color adjustment plate includes a plurality of two-dimensional transparent substrates and a dielectric multilayer film formed on the entire outer surface of the transparent substrates, the dielectric multilayer film being formed by alternately stacking high refractive index layers and low refractive index layers; a solar cell module, wherein the dielectric multilayer film is configured to satisfy the following (1-1) to (1-3), (1-5), and (1-6); (1-1) When white light is incident from a vertical direction, the reflected light reflected in the same direction as the vertical direction exhibits spectral reflectance characteristics having multiple reflection peaks in a wavelength range of 380 nm to 780 nm, (1-2) The plurality of reflection peaks include at least one first main reflection peak at a wavelength less than 520 nm and one second main reflection peak at a wavelength equal to or greater than 520 nm; (1-3) The plurality of reflection peaks exhibit a reflectance of 20% or more relative to a reflection peak exhibiting a maximum reflectance among the reflection peaks in the wavelength range. (1-5) the full width at half maximum (FWHM) of at least one of the first main reflection peak and the second main reflection peak is 200 nm or less; (1-6) The reflectances of the first and second main reflection peaks are both 70% or less.

16. The solar cell module described in claim 15, wherein one of the film-formed surface of the transparent substrate on which the dielectric multilayer film is formed and the non-film-formed surface on which the dielectric multilayer film is not formed is formed as a diffuse reflection surface having an uneven structure.

17. The solar cell module according to claim 15 , wherein the non-film-formed surface is formed as a diffuse reflecting surface.

18. The solar cell module according to claim 15 , wherein the transparent substrate is a diffusion plate.

19. A substrate; a dielectric multilayer film in which high-refractive index layers and low-refractive index layers are alternately stacked on at least one of the front surface and the back surface of the substrate; The dielectric multilayer film is a color adjustment plate configured to satisfy the following (1-1) to (1-3): (1-1) When white light is incident from a vertical direction, the reflected light reflected in the same direction as the vertical direction exhibits spectral reflectance characteristics having multiple reflection peaks in a wavelength range of 380 nm to 780 nm, (1-2) The plurality of reflection peaks include at least one first main reflection peak at a wavelength less than 520 nm and one second main reflection peak at a wavelength equal to or greater than 520 nm; (1-3) The plurality of reflection peaks exhibit a reflectance of 20% or more relative to the reflection peak exhibiting the maximum reflectance among the reflection peaks in the wavelength range.

20. 20. The color-tuning plate of claim 19, wherein the substrate is a diffuser plate.

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