WO2013133105A1

WO2013133105A1 - Light guide, photovoltaic module, and photovoltaic power-generation device

Info

Publication number: WO2013133105A1
Application number: PCT/JP2013/055158
Authority: WO
Inventors: 英臣由井; 前田　強
Original assignee: シャープ株式会社
Priority date: 2012-03-07
Filing date: 2013-02-27
Publication date: 2013-09-12
Also published as: JP2015099807A

Abstract

A light guide is provided with a first transparent layer, and an optical functional material dispersed inside the first transparent layer. If the peak wavelength of the absorption spectrum of the optical functional material is λ1, the peak wavelength of the emission spectrum of the optical functional material is λ2, the refractive index of the first transparent layer at wavelength λ1 is n1(λ1), and the refractive index of the first transparent layer at wavelength λ2 is n1(λ2), then n1(λ1) and n1(λ2) satisfy the relationship n1(λ1) < n1(λ2).

Description

Light guide, solar cell module and solar power generation device

The present invention relates to a light guide, a solar cell module, and a solar power generation device.
This application claims priority on March 7, 2012 based on Japanese Patent Application No. 2012-050524 filed in Japan, the contents of which are incorporated herein by reference.

As a solar power generation device that installs a solar cell element on the end face of a light guide and makes light propagated through the light guide enter the solar cell element to generate power, the solar power generation device described in Patent Document 1 is Are known. The solar power generation device of Patent Document 1 disperses phosphors inside a light guide, and absorbs external light incident from one main surface of the light guide with the phosphor. The fluorescence emitted from the phosphor propagates through the light guide, is emitted from the end face of the light guide, and enters the solar cell element.

JP 58-49860 A

In order to efficiently generate power using a phosphor, it is important how to propagate the fluorescence emitted from the phosphor to the end face of the light guide without loss. The efficiency of confining the fluorescence inside the light guide is determined by the refractive index of the light guide, and the greater the refractive index of the light guide, the greater the fluorescence confinement efficiency. Therefore, in order to increase the fluorescence confinement efficiency, it is effective to use a light guide having a large refractive index. However, if the refractive index of the light guide is increased, the surface reflection of the light guide increases, and external light Is not sufficiently incident on the inside of the light guide.

An object of the present invention is to provide a light guide, a solar cell module, and a solar power generation device that can efficiently generate power using external light.

The light guide according to the first aspect of the present invention includes a first transparent layer and an optical functional material dispersed inside the first transparent layer, and the peak wavelength of the absorption spectrum of the optical functional material is λ1. And the peak wavelength of the emission spectrum of the optical functional material is λ2, the refractive index of the first transparent layer at the wavelength λ1 is n1 (λ1), and the refractive index of the first transparent layer at the wavelength λ2 is n1 ( λ2), n1 (λ1) and n1 (λ2) satisfy the relationship n1 (λ1) <n1 (λ2).

A light guide according to a second aspect of the present invention includes a first transparent layer and a plurality of types of optical functional materials dispersed inside the first transparent layer. The peak wavelength of the absorption spectrum of any one type of optical functional material is λ1, the peak wavelength of the emission spectrum of the optical functional material having the largest emission spectrum peak wavelength among the plurality of types of optical functional materials is λ2, and the wavelength When the refractive index of the first transparent layer at λ1 is n1 (λ1) and the refractive index of the first transparent layer at the wavelength λ2 is n1 (λ2), the n1 (λ1) and the n1 (λ2) Satisfies the relationship of n1 (λ1) <n1 (λ2).

When the peak wavelength of the emission spectrum of any optical functional material among the plurality of types of optical functional materials is λ1, n1 (λ1) and n1 (λ2) satisfy n1 (λ1) <n1 (λ2). You may satisfy the relationship.

The energy transfer may occur between the plurality of types of optical functional materials, and light may be emitted from the optical functional material having the largest peak wavelength of the emission spectrum.

A second transparent layer is provided on one side of the first transparent layer, the refractive index of the second transparent layer at the wavelength λ1 is n2 (λ1), and the refractive index of the second transparent layer at the wavelength λ2 is n2. When (λ2), n2 (λ1) and n2 (λ2) may satisfy the relationship n2 (λ1) <n2 (λ2).

The n2 (λ2) and the n1 (λ2) may satisfy a relationship of n2 (λ2) ≧ n1 (λ2).

A second transparent layer is provided on one side of the first transparent layer, the refractive index of the second transparent layer at the wavelength λ1 is n2 (λ1), and the refractive index of the second transparent layer at the wavelength λ2 is n2. When (λ2), n2 (λ1) and n2 (λ2) satisfy the relationship n2 (λ1)> n2 (λ2), and n2 (λ2) and n1 (λ2) are n2 ( The relationship of λ2) ≧ n1 (λ2) may be satisfied.

A third transparent layer is provided on the other surface side of the first transparent layer, and when the refractive index of the third transparent layer at the wavelength λ2 is n3 (λ2), the n3 (λ2) and the n1 (λ2 ) May satisfy the relationship of n3 (λ2) ≧ n1 (λ2).

The light guide of the third aspect of the present invention includes a first transparent layer, an optical functional material dispersed inside the first transparent layer, and a second transparent provided on one surface side of the first transparent layer. A peak wavelength of the absorption spectrum of the optical functional material is λ1, a peak wavelength of the emission spectrum of the optical functional material is λ2, and a refractive index of the second transparent layer at the wavelength λ1 is n2 (λ1 ), And the refractive index of the second transparent layer at the wavelength λ2 is n2 (λ2), the relationship between n2 (λ1) and n2 (λ2) is n2 (λ1) <n2 (λ2). Fulfill.

The light guide of the 4th form of this invention was provided in the 1st transparent layer, the multiple types of optical functional material disperse | distributed inside the said 1st transparent layer, and the one surface side of the said 1st transparent layer. A peak wavelength of an absorption spectrum of any one of the plurality of types of optical functional materials is λ1, and the peak of the emission spectrum is the highest among the plurality of types of optical functional materials. The peak wavelength of the emission spectrum of the optical functional material having a large wavelength is λ2, the refractive index of the second transparent layer at the wavelength λ1 is n2 (λ1), and the refractive index of the second transparent layer at the wavelength λ2 is n2 ( λ2), n2 (λ1) and n2 (λ2) satisfy the relationship n2 (λ1) <n2 (λ2).

When the peak wavelength of the emission spectrum of an arbitrary optical functional material among the plural types of optical functional materials is λ1, the n2 (λ1) and the n2 (λ2) satisfy n2 (λ1) <n2 (λ2). You may satisfy the relationship.

When the refractive index of the first transparent layer at the wavelength λ1 is n1 (λ1) and the refractive index of the first transparent layer at the wavelength λ2 is n1 (λ2), the n1 (λ1) and the n1 ( λ2) may satisfy the relationship n1 (λ1) <n1 (λ2).

When the refractive index of the first transparent layer at the wavelength λ1 is n1 (λ1) and the refractive index of the first transparent layer at the wavelength λ2 is n1 (λ2), the n1 (λ1) and the n1 ( λ2) may satisfy the relationship n1 (λ1)> n1 (λ2).

When a third transparent layer is provided between the first transparent layer and the second transparent layer, and the refractive index of the third transparent layer at the wavelength λ2 is n3 (λ2), the n3 (λ2) And n1 (λ2) may satisfy the relationship n3 (λ2) ≧ n1 (λ2).

When the refractive index of the third transparent layer at the wavelength λ1 is n3 (λ1), the n3 (λ1), the n2 (λ1), and the n1 (λ1) are n2 (λ1) ≦ n3 (λ1) ≦ n1 (λ1) may be satisfied.

The solar cell module of the present invention includes the light guide of the present invention and a solar cell element that receives light emitted from the light guide.

The light incident surface of the light guide may be a flat surface.

The light guide may be configured as a flat plate-shaped member, and the solar cell element may receive the fluorescence emitted from an end surface of the light guide that is a light emission surface.

At least a part of the light incident surface of the light guide may be a bent or curved surface.

The light guide may be configured as a curved plate-shaped member, and the solar cell element may receive the fluorescence emitted from an end surface of the light guide that is a light emission surface.

The light guide may be configured as a cylindrical member, and the solar cell element may receive the fluorescence emitted from an end surface of the light guide that is a light emission surface.

The light guide may be configured as a columnar member, and the solar cell element may receive the light emitted from an end surface of the light guide that is a light emission surface.

A plurality of unit units each including the light guide body and the solar cell element may be installed adjacent to each other, and the plurality of unit units may be flexibly connected to each other by a string-like connecting member. .

A plurality of unit units each including the light guide body and the solar cell element as a set may be installed adjacent to each other, and the plurality of unit units may be connected with a space therebetween.

The solar power generation device of the present invention includes the solar cell module of the present invention.

According to the present invention, it is possible to provide a light guide, a solar cell module, and a solar power generation device that can efficiently generate power using external light.

It is a schematic perspective view of the solar cell module of 1st Embodiment. It is sectional drawing of a solar cell module. It is a figure which shows the emission spectrum and absorption spectrum of fluorescent substance. It is a figure which shows the wavelength dispersion characteristic of the refractive index of the base material of a light guide. It is a figure for demonstrating an effect | action at the time of using the base material which shows abnormal dispersion as a base material. It is a figure for demonstrating an effect | action at the time of using the base material which shows normal dispersion as a base material. It is sectional drawing of the solar cell module of 2nd Embodiment. It is a figure which shows the wavelength dispersion characteristic of the refractive index of a 1st transparent layer and a 2nd transparent layer. It is a figure for demonstrating an effect | action at the time of using what shows anomalous dispersion | distribution as a 1st transparent layer and a 2nd transparent layer. It is a figure for demonstrating an effect | action at the time of using what shows normal dispersion | distribution as a 1st transparent layer and a 2nd transparent layer. It is sectional drawing of the solar cell module of 3rd Embodiment. It is a figure which shows the absorption characteristic of fluorescent substance. It is a figure which shows the absorption characteristic of fluorescent substance. It is a figure which shows the light emission characteristic of fluorescent substance. It is a figure which shows the light emission characteristic of fluorescent substance. It is explanatory drawing of the energy transfer by photoluminescence. It is explanatory drawing of the energy transfer by a Forster mechanism. It is explanatory drawing of the generation mechanism of the energy transfer by a Forster mechanism. It is a figure which shows the energy transfer by a Forster mechanism. It is a figure which shows the spectral sensitivity curve of an amorphous silicon solar cell with the emission spectrum of 1st fluorescent substance, the emission spectrum of 2nd fluorescent substance, and the emission spectrum of 3rd fluorescent substance. It is sectional drawing of the solar cell module of 4th Embodiment. It is a figure which shows the wavelength dispersion characteristic of the refractive index of a 1st transparent layer, a 2nd transparent layer, and a 3rd transparent layer. It is sectional drawing of the solar cell module of 5th Embodiment. It is a figure which shows the wavelength dispersion characteristic of the refractive index of a 1st transparent layer and a 2nd transparent layer. It is sectional drawing of the solar cell module of 6th Embodiment. It is a figure which shows the wavelength dispersion characteristic of the refractive index of a 1st transparent layer and a 2nd transparent layer. It is sectional drawing of the solar cell module of 7th Embodiment. It is a figure which shows the wavelength dispersion characteristic of the refractive index of a 1st transparent layer, a 2nd transparent layer, and a 3rd transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 2nd transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 1st transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 3rd transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 2nd transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 1st transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 3rd transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 2nd transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 1st transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 3rd transparent layer. It is sectional drawing of the solar cell module of 8th Embodiment. It is a figure which shows the wavelength dispersion characteristic of the refractive index of a 1st transparent layer, a 2nd transparent layer, and a 3rd transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 1st transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 1st transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 3rd transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 2nd transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 1st transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 3rd transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 2nd transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 1st transparent layer. It is a figure which shows the modification of the wavelength dispersion characteristic of the refractive index of a 3rd transparent layer. It is a schematic diagram of the solar cell module of 9th Embodiment. It is a schematic diagram of the solar cell module of 10th Embodiment. It is a schematic diagram of the solar cell module of 11th Embodiment. It is a schematic block diagram of a solar power generation device.

[First Embodiment]
FIG. 1 is a schematic perspective view of the solar cell module 1 of the first embodiment.

The solar cell module 1 includes a light guide 4 (fluorescent light guide), a solar cell element 6 that receives light emitted from the first end face 4 c of the light guide 4, and the light guide 4 and the solar cell element 6. And a frame 10 that holds the two integrally.

The light guide 4 includes a first main surface 4a that is a light incident surface, a second main surface 4b that faces the first main surface 4a, and a first end surface 4c that is a light emission surface.

The light guide 4 is a substantially rectangular plate-like member having a first main surface 4a and a second main surface 4b perpendicular to the Z axis (parallel to the XY plane). The light guide 4 is obtained by dispersing an optical functional material in a base material (transparent substrate) made of a highly transparent organic material or inorganic material such as acrylic resin, polycarbonate resin, or glass. Examples of the optical functional material include a phosphor that absorbs ultraviolet light or visible light and emits visible light or infrared light. The light emitted from the phosphor propagates through the light guide 4 and is emitted from the first end face 4 c and is used for power generation by the solar cell element 6.

Note that visible light is light in a wavelength region of 380 nm to 750 nm, ultraviolet light is light in a wavelength region less than 380 nm, and infrared light is light in a wavelength region larger than 750 nm.

The first main surface 4a and the second main surface 4b of the light guide 4 are flat surfaces substantially parallel to the XY plane. Light that travels from the inside of the light guide 4 toward the outside of the light guide 4 (light radiated from the phosphor) is transmitted to the inside of the light guide 4 on the end faces other than the first end face 4 c of the light guide 4. A reflective layer 9 that reflects toward the surface is provided in direct contact with the end surface via an air layer or without an air layer. Light traveling from the inside of the light guide 4 toward the outside of the light guide 4 (light emitted from the phosphor) or the first main surface 4a is incident on the second main surface 4b of the light guide 4 Is reflected by the second main surface 4b via the air layer or the second main surface 4b. The reflection layer 7 reflects the light emitted from the second main surface 4b without being absorbed by the optical functional material toward the inside of the light guide 4. The surface 4b is provided in direct contact with no air layer.

As the reflective layer 7 and the reflective layer 9, a reflective layer made of a metal film such as silver or aluminum, or a reflective layer made of a dielectric multilayer film such as an ESR (Enhanced Special Reflector) reflective film (manufactured by 3M) is used. Can do. The reflective layer 7 and the reflective layer 9 may be a specular reflective layer that specularly reflects incident light, or a scattering reflective layer that scatters and reflects incident light. When a scattering reflection layer is used for the reflection layer 7, the amount of light that goes directly in the direction of the solar cell element 6 increases, so that the light collection efficiency to the solar cell element 6 increases and the amount of power generation increases. In addition, since the reflected light is scattered, changes in the amount of power generation with time and season are averaged. As the scattering reflection layer, micro-fired PET (polyethylene terephthalate) (manufactured by Furukawa Electric) can be used.

The solar cell element 6 is disposed with the light receiving surface facing the first end surface 4 c of the light guide 4. The solar cell element 6 is preferably optically bonded to the first end face 4c. As the solar cell element 6, a known solar cell such as a silicon solar cell, a compound solar cell, or an organic solar cell can be used. Among these, a compound solar cell using a compound semiconductor is suitable as the solar cell element 6 because it can generate power with high efficiency.

1 shows an example in which the solar cell element 6 is installed only on one end face of the light guide 4, the solar cell element 6 may be installed on a plurality of end faces of the light guide 4. When the solar cell element 6 is installed on a part of the end surface (one side, two sides, or three sides) of the light guide 4, the reflective layer 9 may be installed on the end surface where the solar cell element is not installed. preferable.

The frame 10 includes a transmission surface 10 a that transmits the light L on a surface facing the first main surface 4 a of the light guide 4. The transmission surface 10a may be an opening of the frame 10, or may be a transparent member such as glass fitted in the opening of the frame 10. The first main surface 4 a of the light guide 4 that overlaps the transmission surface 10 a of the frame 10 when viewed from the Z direction is the light incident surface of the light guide 4. Further, the first end surface 4 c of the light guide 4 is a light exit surface of the light guide 4. The light guide 4 absorbs a part of the external light incident from the light incident surface by the optical functional material, and condenses the light emitted from the optical functional material on the light exit surface having a smaller area than the light incident surface. Inject outside.

FIG. 2 is a cross-sectional view of the solar cell module 1.

In the case of the present embodiment, a phosphor 8 that absorbs orange light and emits red fluorescence L1 is dispersed in the light guide 4 as an optical functional material. The light guide 4 includes a transparent base material 5 that does not contain a phosphor, and a phosphor 8 that is dispersed inside the base material 5. The substrate 5 is a transparent layer that does not contain a phosphor, but if the phosphor is not intentionally dispersed for the purpose of wavelength conversion inside the light guide plate 4, it contains some phosphor and is completely Even those made of a material that is not transparent can be used as the substrate 5.

FIG. 3 is a diagram showing an emission spectrum and an absorption spectrum of the phosphor 8. The horizontal axis in FIG. 3 is the light wavelength, and the vertical axis is the normalized light intensity.

The phosphor 8 is, for example, BASF Lumogen F RED (trade name). The mixing ratio of the phosphor 8 is, for example, about 0.02% in volume ratio with respect to the base material 5. The peak wavelength λ1 of the absorption spectrum of the phosphor 8 is approximately 580 nm, and the peak wavelength λ2 of the emission spectrum is approximately 610 nm. The peak wavelength λ2 of the emission spectrum of the phosphor 8 is shifted to the longer wavelength side than the peak wavelength λ1 of the absorption spectrum due to the effect of Stokes shift. Note that the phosphor 8 is not limited to Lumogen F RED (trade name) manufactured by BASF, and various known phosphors can be used. The phosphor 8 can absorb a part of the external light L (for example, sunlight) incident on the light incident surface of the light guide 4 and can convert the wavelength to propagate inside the light guide 4. As examples of phosphors other than BASF's Lumogen F RED (trade name), phosphors described in JP-A-2004-45248 and JP-A-2010-263115 may be mentioned.

FIG. 4 is a diagram showing the wavelength dispersion characteristics of the refractive index n1 of the base material 5. FIG. In FIG. 4, the symbol n <b> 0 indicates the refractive index of a medium (for example, air) outside the light guide 4.

In this embodiment, the peak wavelength of the absorption spectrum of the phosphor 8 is λ1, the peak wavelength of the emission spectrum of the phosphor 8 is λ2, the refractive index of the base material 5 at the wavelength λ1 is n1 (λ1), and the wavelength λ2 When the refractive index of the substrate 5 is n1 (λ2), n1 (λ1) and n1 (λ2) satisfy the relationship n1 (λ1) <n1 (λ2). In the wavelength region between the wavelength λ1 and the wavelength λ2, for example, a material exhibiting wavelength dispersion characteristics (anomalous dispersion) such that the refractive index n1 increases as the wavelength λ increases. In the case of the present embodiment, a member that exhibits anomalous dispersion in a wide wavelength region including the wavelength λ1 and the wavelength λ2 is preferably used as the substrate 5, but the wavelength dispersion characteristic of the refractive index of the substrate 5 is not limited to this. As long as it satisfies at least the above-described characteristics, that is, the relationship of n1 (λ1) <n1 (λ2). The anomalous dispersion is a wavelength dispersion characteristic in which the refractive index n1 increases as the wavelength λ increases. A wavelength dispersion characteristic in which the refractive index n1 decreases as the wavelength λ increases is referred to as normal dispersion. Examples of members exhibiting anomalous dispersion are known as disclosed in, for example, JP-A No. 2003-344605, JP-A No. 2006-287243, JP-A No. 6-64942, JP-A No. 8-258208, and the like. Members are available.

FIGS. 5A and 5B are diagrams for explaining the difference in action between the case where the base material 5A showing abnormal dispersion is used as the base material 5 and the case where the base material 5B showing normal dispersion is used.

The refractive index n1 of the base material 5 is such that the surface reflectance R when the external light L is incident on the base material 5 and the confinement efficiency η _trap when the fluorescent light L1 emitted from the phosphor 8 is confined inside the base material 5. To affect. The surface reflectance R indicates the ratio of the light reflected on the surface of the base material 5 out of the light L incident on the surface of the base material 5, and the confinement efficiency η _trap is the fluorescence L1 emitted in all directions. Of these, the ratio of the fluorescence confined inside the base material 5 by total reflection is shown. The surface reflectance R and the confinement efficiency η _trap are expressed by Expression (1) and Expression (2). In the formulas (1) and (2), n is the refractive index of the substrate, θ1 is the incident angle of light, and θ2 is the refractive angle of light.

In the solar cell module 1, the external light L is efficiently taken into the light guide 4 and the fluorescence L1 radiated from the phosphor 8 is led to the solar cell element 6 without waste to improve power generation efficiency. It becomes important in. However, as shown in the formulas (1) and (2), when the surface reflectance R is decreased and the external light L is efficiently taken into the base material 5, the refractive index n1 of the base material 5 is decreased. In order to increase the confinement efficiency η _trap and guide the fluorescence L1 from the phosphor 8 to the solar cell element 6 without waste, the refractive index n1 of the substrate 5 needs to be increased.

In general, the refractive index of a transparent member is not anomalous dispersion as shown in FIG. 4, but shows a chromatic dispersion characteristic of normal dispersion in which the refractive index decreases as the wavelength increases. As shown in FIG. 5B, when a member exhibiting normal dispersion is used as the substrate 5B, the refractive index n1 increases at the absorption wavelength λ1 of the phosphor 8, and the refractive index n1 decreases at the emission wavelength λ2 of the phosphor 8. For this reason, the surface reflectance R (reflected light Lr) increases, and the phosphor 8 cannot sufficiently absorb the external light L. Further, since the confinement efficiency η _trap becomes small, the fluorescence L1 leaking from the base material 5B increases, and it becomes impossible to make the fluorescent light L1 having a sufficient amount of light incident on the solar cell element 6. That is, when the refractive index n1 at the emission wavelength λ2 of the phosphor 8 becomes small, the critical angle when the fluorescence is totally reflected on the surface of the base material 5B becomes small, so that the fluorescence incident on the surface of the base material 5B with a small incident angle. L1 cannot be totally reflected. Since such fluorescence L1 permeate | transmits the base material 5B and leaks outside, as a result, the light quantity of the fluorescence L1 which injects into the solar cell element 6 falls.

On the other hand, as shown in FIG. 5A, when the substrate 5A having a wavelength dispersion characteristic (abnormal dispersion) as shown in FIG. 4 is used, the refractive index n1 becomes small at the absorption wavelength λ1 of the phosphor 8, and the phosphor 8 At the emission wavelength λ2, the refractive index n1 increases. Therefore, the surface reflectance R (reflected light Lr) becomes small, and the phosphor 8 can sufficiently absorb the external light L. Further, since the confinement efficiency η _trap is increased, the fluorescence L1 leaking from the base material 5A is reduced, and a sufficient amount of fluorescence L1 can be incident on the solar cell element 6. That is, when the refractive index n1 at the emission wavelength λ2 of the phosphor 8 is increased, the critical angle when the fluorescence L1 is totally reflected on the surface of the base material 5A is reduced, so that the light is incident on the surface of the base material 5A with a small incident angle. It becomes possible to totally reflect the fluorescence L1. As a result, the light amount of the fluorescence L1 leaking from the base material 5A is reduced, and the light amount of the fluorescence L1 incident on the solar cell element 6 is increased.

As described above, in the solar cell module 1 of the present embodiment, the light guide base material 5 in which the phosphor 8 is dispersed exhibits a relatively small refractive index at the absorption wavelength λ 1 of the phosphor 8. A material having a relatively large refractive index at the emission wavelength λ2 is used. Therefore, the external light L incident on the light guide 4 can be efficiently absorbed by the phosphor 8, and the fluorescence L1 emitted from the phosphor 8 can be guided to the solar cell element 6 without waste. Therefore, it is possible to provide the solar cell module 1 capable of efficiently generating power using the external light L.

1 and 2 show a state in which the light guide 4 is incorporated in the solar cell module 1, only the portion actually used as the light guide 4 is shown, and before the incorporation into the solar cell module 1. The illustration of the incidental configuration is omitted. Actually, the light guide 4 is additionally provided with a protective film for protecting the light incident surface 4a of the light guide 4 in addition to the configuration shown in FIGS. The body 4 may be provided with such a configuration. As such a protective film, a transparent member whose refractive index shows normal dispersion may be used. In the present embodiment, the transparent layer constituting the outermost surface on the light incident side of the light guide 4 is configured as a layer exhibiting anomalous dispersion, but such a state is not necessarily required when distributed as a single light guide. There is no need to distribute it. Therefore, at the stage where the light guide is sold and distributed (implemented), the configuration of the light guide in which the transparent layer on the outermost surface on the light incident side is a layer exhibiting normal dispersion is not excluded. Such a configuration is also included in the technical scope of the present invention.

[Second Embodiment]
FIG. 6 is a cross-sectional view of the solar cell module 11 of the second embodiment. The configuration other than the light guide 12 is the same as that of the solar cell module 1 of the first embodiment. Therefore, here, the configuration of the light guide 12 will be mainly described. Moreover, about the structure which is common in the solar cell module 1 of 1st Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

The light guide 12 includes a transparent light guide 14 and a fluorescent film 13 bonded to the first main surface 14 a of the transparent light guide 14. The fluorescent film 13 and the transparent light guide 14 are disposed in order from the incident side of the external light L. The first main surface 13 a opposite to the transparent light guide 14 of the fluorescent film 13 is a light incident surface of the light guide 12, and the first end surface 13 c of the fluorescent film 13 and the first end surface 14 c of the transparent light guide 14. Is the light exit surface of the light guide 12. The light receiving surface of the solar cell element 6 is disposed so as to face the first end surface 13c of the fluorescent film 13 and the first end surface 14c of the transparent light guide 14 which are light emitting surfaces.

The fluorescent film 13 includes a transparent base material 15 that does not contain a fluorescent material, and a fluorescent material 8 that is dispersed inside the base material 15. The fluorescent film 13 converts part of the external light L (for example, sunlight) incident on the first main surface 12 a into fluorescence and radiates it toward the transparent light guide 14. Part of the fluorescence emitted from the fluorescent film 13 propagates while totally reflecting the inside of the fluorescent film 13 and the transparent light guide 14. The fluorescence emitted from the first end face 13c of the fluorescent film 13 and the first end face 14c of the transparent light guide 14 enters the solar cell element 6 and is used for power generation.

The base material 15 and the transparent light guide 14 are transparent layers that do not contain a phosphor. However, unless the phosphor is intentionally dispersed for the purpose of wavelength conversion inside the fluorescent film 13 and the transparent light guide 14, it is made of a material that contains some phosphor and is not completely transparent. Even if it is a thing, it can be used as the base material 15 and the transparent light guide 14. FIG. Hereinafter, the base material 15 of the fluorescent film 13 may be referred to as a first transparent layer, and the transparent light guide 14 may be referred to as a second transparent layer. The second transparent layer is a transparent layer provided on one side of the first transparent layer.

FIG. 7 is a diagram showing the wavelength dispersion characteristics of the refractive index n1 of the first transparent layer 15 and the refractive index n2 of the second transparent layer. In the present embodiment, the first transparent layer 15 and the second transparent layer 14 are formed of the same material, and the refractive indexes n1 and n2 of the first transparent layer 15 and the second transparent layer 14 exhibit the same wavelength dispersion characteristics. .

In this embodiment, the peak wavelength of the absorption spectrum of the phosphor 8 is λ1, the peak wavelength of the emission spectrum of the phosphor 8 is λ2, the refractive index of the first transparent layer 15 at the wavelength λ1 is n1 (λ1), and the wavelength The refractive index of the second transparent layer 14 at λ1 is n2 (λ1), the refractive index of the first transparent layer 15 at wavelength λ2 is n1 (λ2), and the refractive index of the second transparent layer 14 at wavelength λ2 is n2 (λ2). ), N1 (λ1), n2 (λ1), n1 (λ2), and n2 (λ2) satisfy the relationship of n1 (λ1) <n1 (λ2) and n2 (λ1) <n2 (λ2) It is supposed to satisfy. In the wavelength region between the wavelength λ1 and the wavelength λ2, for example, wavelength dispersion characteristics (anomalous dispersion) are shown such that the refractive indexes n1 and n2 increase as the wavelength λ increases. As the first transparent layer 15 and the second transparent layer 14, a member that exhibits anomalous dispersion in a wide wavelength region including the wavelengths λ1 and λ2 is preferably used. As such a member, a member similar to that shown in the first embodiment can be used.

8A and 8B show the case where the first transparent layer 15 and the second transparent layer 14 exhibit anomalous dispersion (the first transparent layer 15A and the second transparent layer 14A) and the normal dispersion (the first transparent layer 15 and the second transparent layer 14A). It is a figure for demonstrating the difference in an effect | action at the time of using the transparent layer 15B and the 2nd transparent layer 14B).

As shown in FIG. 8B, when members exhibiting normal dispersion are used as the first transparent layer 15B and the second transparent layer 14B, the refractive index n2 increases at the absorption wavelength λ1 of the phosphor 8, and the emission wavelength λ2 of the phosphor 8 Then, the refractive index n2 becomes small. For this reason, the surface reflectance R (reflected light Lr) increases, and the phosphor 8 cannot sufficiently absorb the external light L. Further, since the confinement efficiency η _trap becomes small, the fluorescence L1 leaking out from the first transparent layer 15B and the second transparent layer 14B increases, and the fluorescent light L1 having a sufficient amount of light cannot enter the solar cell element 6. That is, when the refractive index n2 at the emission wavelength λ2 of the phosphor 8 becomes small, the critical angle when the fluorescence L1 is totally reflected on the surfaces of the first transparent layer 15B and the second transparent layer 14B becomes small. The fluorescence L1 incident at a small incident angle on the surfaces of 15B and the second transparent layer 14B cannot be totally reflected. Such fluorescence L1 passes through the first transparent layer 15B and the second transparent layer 14B and leaks to the outside. As a result, the amount of fluorescence L1 incident on the solar cell element 6 is reduced.

On the other hand, as shown in FIG. 8A, when the first transparent layer 15 and the second transparent layer 14 exhibiting anomalous dispersion are used, the refractive index n2 becomes small at the absorption wavelength λ1 of the phosphor 8, and the phosphor 8 emits light. At the wavelength λ2, the refractive index n2 increases. Therefore, the surface reflectance R (reflected light Lr) becomes small, and the phosphor 8 can sufficiently absorb the external light L. Further, since the confinement efficiency η _trap is increased, the fluorescence L1 leaking out from the first transparent layer 15A and the second transparent layer 14A is reduced, and a sufficient amount of fluorescence L1 can be incident on the solar cell element 6. . That is, when the refractive index n2 at the emission wavelength λ2 of the phosphor 8 is increased, the critical angle when the fluorescence L1 is totally reflected on the surfaces of the first transparent layer 15A and the second transparent layer 14A is reduced. It becomes possible to totally reflect the fluorescence L1 incident on the surfaces of 15A and the second transparent layer 14A at a small incident angle. As a result, the light amount of the fluorescence L1 leaking from the first transparent layer 15A and the second transparent layer 14A decreases, and the light amount of the fluorescence L1 incident on the solar cell element 6 increases.

In the present embodiment, since the first transparent layer 15A and the second transparent layer 14A are formed of the same material, the fluorescence L1 emitted from the phosphor 8 is the first transparent layer 15A and the second transparent layer 14A. It propagates inside the first transparent layer 15A and the second transparent layer 14A without being surface-reflected at the interface. Since the fluorescence L1 emitted from the phosphor 8 is not confined in the first transparent layer 15A (fluorescence film 13), the light loss due to the self-absorption of the phosphor 8 is reduced.

As described above, according to the solar cell module of the present embodiment, in addition to the effect of the first embodiment, an effect that the loss due to the self-absorption of the phosphor 8 can be reduced is obtained. Therefore, the solar cell module 11 capable of generating power more efficiently is provided.

In addition, in this embodiment, although the 1st transparent layer 15 and the 2nd transparent layer 14 were formed with the same material, the 1st transparent layer 15 and the 2nd transparent layer 14 do not necessarily need to be formed with the same material. Even if the first transparent layer 15 and the second transparent layer 14 are formed of different materials, if n1 (λ2) and n2 (λ2) are sufficiently close, the fluorescence emitted from the phosphor 8 is emitted from the first transparent layer 15. And can be propagated across the second transparent layer 14. For example, when both n1 and n2 indicate anomalous dispersion, or n1 indicates anomalous dispersion and n2 indicates a normal dispersion, n1 (λ2) and n2 (λ2) are sufficiently close In the case, the above-described effects can be obtained. In this case, if n1 (λ2) and n2 (λ2) satisfy the relationship n2 (λ2) ≧ n1 (λ2), the surface reflection at the interface between the first transparent layer 15 and the second transparent layer 14 , And the fluorescence emitted from the phosphor 8 is easily taken into the second transparent layer 14 from the first transparent layer 15.

In the present embodiment, the light guide 12 is composed of two layers of the fluorescent film 13 and the transparent light guide 14, but the configuration of the light guide 12 is not limited to this. One or more other transparent layers (third transparent layer: refractive index n3) are disposed between the first transparent layer 15 and the second transparent layer 14, and the surface of the first transparent layer 15 opposite to the second transparent layer 14 Alternatively, the second transparent layer 14 may be provided on the side opposite to the first transparent layer 15. Also in this case, if the refractive indexes of n1 (λ2), n2 (λ2), and n3 (λ2) are sufficiently close, the fluorescence emitted from the phosphor 8 is emitted from the first transparent layer 15, the second transparent layer 14, and the third transparent layer. It can be propagated across the transparent layer. For example, if the third transparent layer has a refractive index n3 exhibiting anomalous dispersion, n1 (λ2), n2 (λ2), and n3 (λ2) are close to each other, so that the above-described effect can be easily obtained.

The third transparent layer may be provided on the side of the first transparent layer 15 opposite to the second transparent layer 14. In this case, the third transparent layer preferably exhibits anomalous dispersion, but any transparent layer generally used as an antireflection layer may be used even if it exhibits normal dispersion.

[Third Embodiment]
FIG. 9 is a cross-sectional view of the solar cell module 16 of the third embodiment. The configuration other than the light guide 17 is the same as that of the solar cell module 1 of the first embodiment. Therefore, here, the configuration of the light guide 17 will be mainly described. Moreover, about the structure which is common in the solar cell module 1 of 1st Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

In the case of this embodiment, inside the light guide 17 (base material 5), as an optical functional material, a plurality of types of phosphors having different absorption wavelength ranges (in FIG. 9, for example, the first phosphor 8a and the second fluorescence). The body 8b and the third phosphor 8c) are dispersed. The first phosphor 8a absorbs ultraviolet light and emits blue fluorescence, the second phosphor 8b absorbs blue light and emits green fluorescence, and the third phosphor 8c emits green light. Absorbs and emits red fluorescence. The 1st fluorescent substance 8a, the 2nd fluorescent substance 8b, and the 3rd fluorescent substance 8c are disperse | distributed inside the transparent base material 5 in which a refractive index shows anomalous dispersion | distribution. The mixing ratio of the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c is as follows. The mixing ratio of the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c is shown as a volume ratio with respect to the substrate 5.

The first phosphor 8a is BASF Lumogen F Violet 570 (trade name) 0.02%. The second phosphor 8b is BASF Lumogen F Yellow 083 (trade name) 0.02%. The third phosphor 8c is BASF's Lumogen F Red 305 (trade name) 0.02%.

The light guide 17 includes a first main surface 17a that is a light incident surface, a second main surface 17b that faces the first main surface 17a, and a first end surface 17c that is a light emission surface. The solar cell element 6 is disposed with the light receiving surface facing the first end surface 17 c of the light guide 17. On the end face other than the first end face 17 c of the light guide body 17, light traveling from the inside of the light guide body 17 toward the outside of the light guide body 17 (light radiated from the phosphor) is transmitted to the inside of the light guide body 17. A reflective layer 9 that reflects toward the surface is provided in direct contact with the end surface via an air layer or without an air layer. Light traveling from the inside of the light guide 17 toward the outside of the light guide 17 (light emitted from the phosphor) or the first main surface 17a enters the second main surface 17b of the light guide 17. The reflective layer 7 that reflects the light emitted from the second main surface 17b toward the inside of the light guide body 17 without being absorbed by the optical functional material is formed on the second main surface 17b via the air layer or the second main surface. The surface 17b is provided in direct contact with no air layer.

10 to 13 are diagrams showing the emission characteristics and absorption characteristics of the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c. In FIG. 10, “first phosphor” indicates the spectrum of sunlight after ultraviolet light is absorbed by the first phosphor 8a, and “second phosphor” indicates that blue light is emitted by the second phosphor 8b. The spectrum of sunlight after being absorbed is shown, and “third phosphor” shows the spectrum of sunlight after green light is absorbed by the third phosphor 8c. In FIG. 11, “first phosphor + second phosphor + third phosphor” absorbs ultraviolet light, blue light, and green light by the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c. The spectrum of sunlight after being applied. In FIG. 12, “first phosphor” is the emission spectrum of the first phosphor 8a, “second phosphor” is the emission spectrum of the second phosphor 8b, and “third phosphor” is It is an emission spectrum of the 3rd fluorescent substance 8c. In FIG. 13, “first phosphor + second phosphor + third phosphor” is emitted from the first end face of the light guide including the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c. Is the spectrum of the emitted light.

As shown in FIGS. 10 and 11, the first phosphor 8a absorbs light having a wavelength of approximately 420 nm or less, and the second phosphor 8b absorbs light having a wavelength of approximately 420 nm or more and 520 nm or less. The phosphor 8c absorbs light having a wavelength of approximately 520 nm or more and 620 nm or less. The first phosphor 8a, the second phosphor 8b, and the third phosphor 8c absorb almost all light having a wavelength of 620 nm or less in the sunlight incident on the light guide. In the sunlight spectrum, the proportion of light having a wavelength of 620 nm or less is about 37%. Therefore, 37% of the light incident on the light incident surface of the light guide is absorbed by the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c included in the light guide.

As shown in FIG. 12, the emission spectrum of the first phosphor 8a has a peak wavelength at 430 nm, the emission spectrum of the second phosphor 8b has a peak wavelength at 520 nm, and the emission of the third phosphor 8c. The spectrum has a peak wavelength at 630 nm. However, as shown in FIG. 13, the spectrum of light emitted from the first end face of the light guide including the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c is the same as that of the third phosphor 8c. It has a peak wavelength only at a wavelength corresponding to the peak wavelength (630 nm) of the emission spectrum, and the peak wavelength (430 nm) of the emission spectrum of the first phosphor 8a and the peak wavelength (520 nm) of the emission spectrum of the second phosphor 8b. The corresponding wavelength does not have a peak wavelength.

The cause of the disappearance of the emission spectrum peak corresponding to the first phosphor 8a and the emission spectrum peak corresponding to the second phosphor 8b is the energy transfer between the phosphors by photoluminescence (PL) and the Forster mechanism. Examples thereof include energy transfer between phosphors by (fluorescence resonance energy transfer). Energy transfer by photoluminescence occurs when fluorescence emitted from one phosphor is used as excitation energy for another phosphor. In the Förster mechanism, excitation energy directly moves between two adjacent phosphors by electron resonance without going through such light emission and absorption processes. Since energy transfer between phosphors by the Förster mechanism is performed without going through light emission and absorption processes, energy loss is small under optimum conditions. Therefore, it contributes to the improvement of the power generation efficiency of the solar cell module. In the present embodiment, in order to efficiently generate power while suppressing energy loss, the density of the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c is increased, and the Forster mechanism is used between the phosphors. Energy transfer is performed.

Here, the Förster mechanism will be described with reference to FIGS. 14A to 15B. FIG. 14A is a diagram illustrating energy transfer by photoluminescence, and FIG. 14B is a diagram illustrating energy transfer by the Forster mechanism. FIG. 15A is a diagram for explaining a generation mechanism of energy transfer by the Förster mechanism, and FIG. 15B is a diagram showing energy transfer by the Förster mechanism.

As shown in FIG. 14B, in the phosphor of organic molecules or inorganic nanoparticles, energy transfer may occur from the molecule A in the excited state to the molecule B in the ground state by the Forster mechanism. In the phosphor, when the molecule A is excited and undergoes energy transfer to the molecule B, the molecule B emits light. This energy transfer depends on the distance between molecules, the emission spectrum of molecule A, and the absorption spectrum of molecule B. When the molecule A is the host molecule and the molecule B is the guest molecule, the rate constant k _{H → G} (movement probability) when energy is transferred is as shown in the equation (3).

In Equation (3), ν is the frequency, f ′ _H (ν) is the emission spectrum of the host molecule A, ε (ν) is the absorption spectrum of the guest molecule B, N is the Avogadro constant, n is the refractive index, τ ₀ is the fluorescence lifetime of the host molecule A, R is the intermolecular distance, and K ² is the transition dipole moment (2/3 at random).

When the rate constant is large, energy transfer tends to occur between the phosphors. In order to obtain a large rate constant, it is desirable that the following conditions are satisfied.
[1] The overlap between the emission spectrum of the host molecule A and the absorption spectrum of the guest molecule is large.
[2] The extinction coefficient of guest molecule B is large.
[3] The distance between the host molecule A and the guest molecule B is small.

[1] represents the ease of resonance between two adjacent phosphors. For example, as shown in FIG. 15A, when the peak wavelength of the emission spectrum of the host molecule A is close to the peak wavelength of the absorption spectrum of the guest molecule B, energy transfer due to the Forster mechanism is likely to occur. As shown in FIG. 15B, when the guest molecule B in the ground state exists in the vicinity of the host molecule A in the excited state, the wave function of the guest molecule A changes due to the resonance properties, and the host molecule A in the ground state and the excited state in the excited state. Guest molecule B is formed. Thereby, energy transfer occurs between the host molecule A and the guest molecule B, and the guest molecule B emits light.

In the above [3], the intermolecular distance at which energy transfer by the Forster mechanism occurs is usually about 10 nm. If the conditions are met, energy transfer occurs even when the intermolecular distance is about 20 nm. If the mixing ratio of the first phosphor, the second phosphor, and the third phosphor described above is used, the distance between the phosphors is shorter than 20 nm. Therefore, energy transfer by the Forster mechanism can occur sufficiently. Moreover, the emission spectrum and absorption spectrum of the first phosphor, the second phosphor, and the third phosphor shown in FIGS. 10 and 12 sufficiently satisfy the condition [1]. Therefore, energy transfer from the first phosphor to the second phosphor and energy transfer from the second phosphor to the third phosphor occur, and the first phosphor, the second phosphor, and the third phosphor in this order. Cascade type energy transfer occurs.

In the light guide, although the phosphors having the three different emission spectra (the first phosphor, the second phosphor, and the third phosphor) are mixed, the light guide is substantially affected by the energy transfer by the Förster mechanism. In this case, only the emission of the third phosphor occurs. The emission quantum efficiency of the third phosphor is, for example, 92%. Therefore, by mixing the first phosphor, the second phosphor, and the third phosphor in the light guide, light in the wavelength region up to 620 nm is absorbed, and red light emission with a peak wavelength of 630 nm is achieved with an efficiency of 92%. Can be generated.

This type of energy transfer phenomenon is unique to organic phosphors and is generally considered not to occur in inorganic phosphors, but in some inorganic nanoparticle phosphors such as quantum dots, Those that cause energy transfer between inorganic materials or between inorganic materials and organic materials by a star mechanism are known.

For example, energy transfer occurs between two types of quantum dots having different sizes of ZnO / MgZnO core / shell structure. Since a quantum dot having a dimensional ratio of 1: √2 has a resonating exciton level, for example, 2 having a radius of 3 nm (peak wavelength of emission spectrum: 350 nm) and a radius of 4.5 nm (peak wavelength of emission spectrum: 357 nm). Between types of quantum dots, energy transfer occurs from small to large quantum dots. Energy transfer also occurs between two different sized quantum dots of the CdSe / ZnS core-shell structure. In addition, Mn2 + doped ZnSe quantum dots having a diameter of 8 nm to 9 nm have emission peaks at 450 nm and 580 nm, and are dye molecules such as 1 ′, 3′-dihydro-1 ′, 3 ′, 3′-trimethyl-6-nitrospiro [ 2H-1-benzopyran-2,2 '-(2H) -indole] is well consistent with the light absorption spectrum of a ring-opened Spiropyran molecule (SPO open; Merocynanine form) obtained by irradiating UV rays to Energy transfer to the dye molecule occurs. In general, an inorganic phosphor is superior in light resistance as compared with an organic phosphor, and thus is advantageous when used for a long period of time.

Normally, when two types of phosphors are mixed, as shown in FIG. 14A, first, phosphor A emits light with a certain efficiency, enters phosphor B, and processes of light absorption and light emission by phosphor B are performed. As a result, light is emitted from the phosphor B. In such energy transfer by photoluminescence, energy loss occurs in the light emission process in the phosphor A and the light absorption process in the phosphor B, and the energy transfer efficiency is small.

On the other hand, in the energy transfer by the Forster mechanism shown in FIG. 14B, only the energy moves directly between the phosphors, so that the energy transfer efficiency can be almost 100%, resulting in the energy transfer with high efficiency. Can be made.

In addition, energy transfer by the Forster mechanism occurs not only in a luminescent material such as a phosphor, but also in a non-luminescent material that is excited by external light but deactivates without generating light. The final power generation amount depends on the fluorescence quantum yield of the guest molecule and does not depend on the fluorescence quantum yield of the host molecule. Therefore, even if only the guest molecule is composed of a phosphor having a high fluorescence quantum yield and the host molecule is composed of a phosphor having a low fluorescence quantum yield or a non-light emitting material that does not emit fluorescence, the same amount of power generation can be obtained. Therefore, as compared with the case where a high fluorescence quantum yield is required for all phosphors, such as when energy transfer is performed by photoluminescence, the range of material selection for the host molecule is widened.

FIG. 16 is a diagram showing a spectral sensitivity curve of an amorphous silicon solar cell as an example of the solar cell element 6 together with an emission spectrum of the first phosphor, an emission spectrum of the second phosphor, and an emission spectrum of the third phosphor.

The spectrum of the light L1 emitted from the first end face 17c of the light guide body 17 substantially coincides with the emission spectrum of the third phosphor 8c. Therefore, the solar cell element 6 should just have a high sensitivity in the peak wavelength (630 nm) of the emission spectrum of the 3rd fluorescent substance 8c. As shown in FIG. 16, the amorphous silicon solar cell has the highest spectral sensitivity with respect to light having a wavelength near 600 nm. Comparing the spectral sensitivities of the amorphous silicon solar cells at the peak wavelengths of the emission spectra of the first phosphor, the second phosphor and the third phosphor, the peak wavelength of the emission spectrum of the third phosphor having the largest peak wavelength of the emission spectrum The spectral sensitivity of the amorphous silicon solar cell at is higher than the spectral sensitivity of the amorphous silicon solar cell at the peak wavelength of the emission spectrum of any of the other phosphors (first phosphor and second phosphor) provided in the light guide. large. Therefore, if an amorphous silicon solar cell is used as the solar cell element 6, power generation can be performed with high efficiency.

As described above, in the solar cell module 16 of the present embodiment, a part of the external light L incident on the light incident surface 17a is converted into a plurality of optical functional materials (first phosphor 8a, second phosphor 8b, third fluorescence). The light L1 emitted from the optical functional material (third phosphor 8c) having the largest peak wavelength of the emission spectrum, which is absorbed by the body 8c), causes energy transfer by the Forster mechanism between the plurality of optical functional materials. The light is condensed on the first end surface 17 c of the light guide 17 having a smaller area than the light incident surface 17 a and is incident on the solar cell element 6. Therefore, as the solar cell element 6, a solar cell having very high spectral sensitivity in a limited narrow wavelength range can be used, and a solar cell module with high power generation efficiency is provided.

[Fourth Embodiment]
FIG. 17 is a cross-sectional view of the solar cell module 18 of the fourth embodiment. The configuration other than the light guide 19 is the same as that of the solar cell module 16 of the third embodiment. Therefore, here, the configuration of the light guide 19 will be mainly described. Moreover, about the structure which is common in the solar cell module 16 of 3rd Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

The light guide 19 includes a transparent light guide 22, a fluorescent film 20 adhered to the first main surface 22a of the transparent light guide 22, a transparent protective film 21 covering the first main surface 20a of the fluorescent film 20, It has. The transparent protective film 21, the fluorescent film 20, and the transparent light guide 22 are arranged in order from the incident side of the external light L. The first main surface 21a of the transparent protective film 21 opposite to the fluorescent film 20 is a light incident surface of the light guide 19, and the first end surface 21c of the transparent protective film 21, the first end surface 20c of the fluorescent film 20, and the transparent film. The first end face 22 c of the light guide 22 is a light exit surface of the light guide 19. The light receiving surface of the solar cell element 6 is disposed so as to face the first end surface 21c of the transparent protective film 21, which is a light emitting surface, the first end surface 20c of the fluorescent film 20, and the first end surface 22c of the transparent light guide 22. Yes.

The fluorescent film 20 includes a transparent base material 23 that does not contain a phosphor and a plurality of optical functional materials dispersed in the base material 23 (in FIG. 17, the first phosphor 8a, the second phosphor 8b, and the third phosphor Phosphor 8c). The fluorescent film 20 converts part of the external light L (for example, sunlight) incident on the first main surface 20 a into fluorescence and radiates it toward the transparent light guide 22 and the transparent protective film 21. A part of the fluorescence emitted from the fluorescent film 20 propagates while totally reflecting the inside of the transparent protective film 21, the fluorescent film 20, and the transparent light guide 22, and has a light emitting surface (transparent) having a smaller area than the light incident surface. 1st end surface 21c of the protective film 21, the 1st end surface 20c of the fluorescent film 20, and the 1st end surface 22c of the transparent light guide 22) are guide | induced. The fluorescence emitted from the first end face 21c of the transparent protective film 21, the first end face 20c of the fluorescent film 20, and the first end face 22c of the transparent light guide 22 is incident on the solar cell element 6 and used for power generation.

The transparent protective film 21, the base material 23, and the transparent light guide 22 are transparent layers that do not contain a phosphor.
However, if the phosphor is not intentionally dispersed for the purpose of wavelength conversion inside the transparent protective film 21, the fluorescent film 20, and the transparent light guide 22, it contains some phosphor and is not completely transparent. Even those made of materials can be used as the transparent protective film 21, the base material 23, and the transparent light guide 22. Hereinafter, the base material 23 of the fluorescent film 20 may be referred to as a first transparent layer, the transparent protective film 21 may be referred to as a second transparent layer, and the transparent light guide 22 may be referred to as a third transparent layer.

FIG. 18 is a diagram showing the wavelength dispersion characteristics of the refractive index n1 of the first transparent layer 23, the refractive index n2 of the second transparent layer 21, and the refractive index n3 of the third transparent layer 22. In the case of this embodiment, the first transparent layer 23, the second transparent layer 21, and the third transparent layer 22 are formed of the same material, and the first transparent layer 23, the second transparent layer 21, and the third transparent layer 22 are the same. Refractive indexes n1, n2, and n3 exhibit the same wavelength dispersion characteristics.

In the present embodiment, the peak wavelength of the absorption spectrum of at least one of the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c (hereinafter sometimes referred to as a specific phosphor) is λ1. Where the peak wavelength of the emission spectrum of the third phosphor 8c is λ2, the refractive index of the first transparent layer 23 at the wavelength λ1 is n1 (λ1), and the refractive index of the second transparent layer 21 at the wavelength λ1 is n2 (λ1). ), The refractive index of the third transparent layer 22 at the wavelength λ1 is n3 (λ1), the refractive index of the first transparent layer 23 at the wavelength λ2 is n1 (λ2), and the refractive index of the second transparent layer 21 at the wavelength λ2. Is n2 (λ2) and the refractive index of the third transparent layer 22 at the wavelength λ2 is n3 (λ2), n1 (λ1), n2 (λ1), n3 (λ1), n1 (λ2), n2 ( λ2) and n3 (λ2) are n1 The relations (λ1) <n1 (λ2), n2 (λ1) <n2 (λ2), and n3 (λ1) <n3 (λ2) are satisfied. In the wavelength region between the wavelength λ1 and the wavelength λ2, for example, wavelength dispersion characteristics (anomalous dispersion) are shown such that the refractive index n1, n2, n3 increases as the wavelength λ increases. As the first transparent layer 23, the second transparent layer 21, and the third transparent layer 22, a member that exhibits anomalous dispersion in a wide wavelength region including the wavelength λ1 and the wavelength λ2 is preferably used. As such a member, a member similar to that shown in the first embodiment can be used.

In the solar cell module 18 of the present embodiment, the transparent protective film 21 is disposed on the external light incident side of the fluorescent film 20. However, since the transparent protective film 21 having a refractive index exhibiting anomalous dispersion is used, at least light having an absorption wavelength of the specific phosphor can be efficiently taken into the fluorescent film 20, and the third The fluorescence emitted from the phosphor 8c can be guided to the solar cell element 6 without waste. Therefore, it is possible to provide the solar cell module 18 that can efficiently generate power using the external light L. In this case, when the peak wavelength of the absorption spectrum of any phosphor among the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c is λ1, n1 (λ1), n2 (λ1), n3 (Λ1), n1 (λ2), n2 (λ2), and n3 (λ2) are n1 (λ1) <n1 (λ2), n2 (λ1) <n2 (λ2), and n3 (λ1) <n3 (λ2) ), The light having the absorption wavelength of all the phosphors can be efficiently taken into the fluorescent film 20, and more efficient power generation becomes possible.

In the present embodiment, since the first transparent layer 23, the second transparent layer 21 and the third transparent layer 22 are formed of the same material, the fluorescence emitted from the third phosphor 8c is the first transparent layer. Of the first transparent layer 23, the second transparent layer 21, and the third transparent layer 22 without being surface-reflected at the interface between the first transparent layer 23 and the second transparent layer 21 and the interface between the first transparent layer 23 and the third transparent layer 22. Propagate inside. Since the fluorescence emitted from the third phosphor 8c is not confined in the first transparent layer 23 (fluorescent film 20), the light loss due to the self-absorption of the third phosphor 8c is reduced. Therefore, the solar cell module 18 capable of generating power more efficiently is provided.

In the present embodiment, the first transparent layer 23, the second transparent layer 21, and the third transparent layer 22 are formed of the same material, but the first transparent layer 23, the second transparent layer 21, and the third transparent layer 22 are It is not always necessary to form the same material. Even if the first transparent layer 23, the second transparent layer 21, and the third transparent layer 22 are formed of different materials, the third fluorescence can be obtained if n1 (λ2), n2 (λ2), and n3 (λ2) are sufficiently close. The fluorescence emitted from the body 8 c can be propagated across the first transparent layer 23, the second transparent layer 21, and the third transparent layer 22. For example, if n1, n2, and n3 all indicate anomalous dispersion, or n2 indicates anomalous dispersion and n1 and n3 indicate normal dispersion, n1 (λ1), n2 (λ1) When n3 (λ1) is sufficiently close and n1 (λ2), n2 (λ2), and n3 (λ2) are sufficiently close, the above-described effects can be obtained. In this case, n2 (λ2) and n1 (λ2) satisfy the relationship of n2 (λ2) ≧ n1 (λ2), and n3 (λ2) and n1 (λ2) have a relationship of n3 (λ2) ≧ n1 (λ2). If the above condition is satisfied, surface reflection at the interface between the first transparent layer 23 and the second transparent layer 21 and the sea surface between the first transparent layer 23 and the third transparent layer 22 is reduced. The emitted fluorescence is easily taken into the second transparent layer 21 and the third transparent layer 22 from the first transparent layer 23.

[Fifth Embodiment]
FIG. 19 is a cross-sectional view of the solar cell module 24 of the fifth embodiment. The configuration other than the light guide 25 is the same as that of the solar cell module 18 of the fourth embodiment. Therefore, here, the configuration of the light guide 25 will be mainly described. Moreover, about the structure which is common in the solar cell module 18 of 4th Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

The light guide 25 includes a fluorescent film 20 and a transparent light guide 26 bonded to the first main surface 20 a of the fluorescent film 20. The transparent light guide 26 and the fluorescent film 20 are disposed in order from the incident side of the external light L. The first main surface 26 a of the transparent light guide 26 opposite to the fluorescent film 20 is a light incident surface of the light guide 25, and the first end surface 26 c of the transparent light guide 26 and the first end surface 20 c of the fluorescent film 20. Is a light exit surface of the light guide 25. The light receiving surface of the solar cell element 6 is disposed so as to face the first end surface 26c of the transparent light guide 26 and the first end surface 20c of the fluorescent film 20 which are light emitting surfaces.

The base material 23 and the transparent light guide 26 of the fluorescent film 20 are transparent layers that do not contain a fluorescent material. However, unless the phosphor is intentionally dispersed for the purpose of wavelength conversion inside the fluorescent film 20 and the transparent light guide 26, it is made of a material that contains some phosphor and is not completely transparent. Even if it is a thing, it can be used as the base material 23 and the transparent light guide 26. Hereinafter, the base material 23 of the fluorescent film 20 may be referred to as a first transparent layer, and the transparent light guide 26 may be referred to as a second transparent layer.

FIG. 20 is a diagram showing the wavelength dispersion characteristics of the refractive index n1 of the first transparent layer 23 and the refractive index n2 of the second transparent layer 26. FIG. In the present embodiment, the first transparent layer 23 and the second transparent layer 26 are formed of the same material, and the refractive indexes n1 and n2 of the first transparent layer 23 and the second transparent layer 26 exhibit the same wavelength dispersion characteristics. .

In this embodiment, the peak wavelength of the absorption spectrum of at least one of the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c (hereinafter sometimes referred to as a specific phosphor) is set. λ1, the peak wavelength of the emission spectrum of the third phosphor 8c is λ2, the refractive index of the first transparent layer 23 at the wavelength λ1 is n1 (λ1), and the refractive index of the second transparent layer 26 at the wavelength λ1 is n2 ( λ1), the refractive index of the first transparent layer 23 at the wavelength λ2 is n1 (λ2), and the refractive index of the second transparent layer 26 at the wavelength λ2 is n2 (λ2), where n1 (λ1), n2 ( λ1), n1 (λ2), and n2 (λ2) satisfy the relationship of n1 (λ1) <n1 (λ2) and n2 (λ1) <n2 (λ2). In the wavelength region between the wavelength λ1 and the wavelength λ2, for example, wavelength dispersion characteristics (anomalous dispersion) are shown such that the refractive indexes n1 and n2 increase as the wavelength λ increases. As the first transparent layer 23, the second transparent layer 21, and the third transparent layer 22, a member that exhibits anomalous dispersion in a wide wavelength region including the wavelength λ1 and the wavelength λ2 is preferably used. As such a member, a member similar to that shown in the first embodiment can be used.

In the solar cell module 24 of the present embodiment, the transparent light guide 26 is disposed on the external light incident side of the fluorescent film 20. However, since the transparent light guide 26 has a refractive index exhibiting anomalous dispersion, at least light having an absorption wavelength of the specific phosphor can be efficiently taken into the fluorescent film 20, and The fluorescence emitted from the three phosphors 8c can be guided to the solar cell element 6 without waste. Therefore, it is possible to provide the solar cell module 24 that can efficiently generate power using the external light L. In this case, when the peak wavelength of the absorption spectrum of any phosphor among the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c is λ1, n1 (λ1), n2 (λ1), n1 If (λ2) and n2 (λ2) satisfy the relationship of n1 (λ1) <n1 (λ2) and n2 (λ1) <n2 (λ2), the light having the absorption wavelength of all the phosphors The fluorescent film 20 can be efficiently taken in, and more efficient power generation is possible.

In the present embodiment, since the first transparent layer 23 and the third transparent layer 26 are made of the same material, the fluorescence emitted from the third phosphor 8c is the first transparent layer 23 and the second transparent layer. It propagates inside the first transparent layer 23 and the second transparent layer 26 without being surface-reflected at the interface with H.26.
Since the fluorescence emitted from the third phosphor 8c is not confined in the first transparent layer 23 (fluorescent film 20), the light loss due to the self-absorption of the third phosphor 8c is reduced. Therefore, the solar cell module 24 capable of generating power more efficiently is provided.

In addition, in this embodiment, although the 1st transparent layer 23 and the 2nd transparent layer 26 were formed with the same material, the 1st transparent layer 23 and the 2nd transparent layer 26 do not necessarily need to be formed with the same material. Even if the first transparent layer 23 and the second transparent layer 26 are made of different materials, if n1 (λ2) and n2 (λ2) are close enough, the fluorescence emitted from the third phosphor 8c is changed to the first transparent layer. It can be propagated across the layer 23 and the second transparent layer 26. For example, when both n1 and n2 indicate anomalous dispersion, or n2 indicates anomalous dispersion and n1 indicates a normal dispersion, n1 (λ1) and n2 (λ1) are sufficiently close When n1 (λ2) and n2 (λ2) are close enough, the above-described effect can be obtained. In this case, if n1 (λ2) and n2 (λ2) satisfy the relationship n2 (λ2) ≧ n1 (λ2), the surface reflection at the interface between the first transparent layer 23 and the second transparent layer 26 is performed. , And the fluorescence emitted from the third phosphor 8c is easily taken into the second transparent layer 26 from the first transparent layer 23.

[Sixth Embodiment]
FIG. 21 is a cross-sectional view of the solar cell module 27 of the sixth embodiment. The configuration other than the light guide 28 is the same as that of the solar cell module 18 of the fourth embodiment. Therefore, here, the configuration of the light guide 28 will be mainly described. Moreover, about the structure which is common in the solar cell module 18 of 4th Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

The light guide 28 includes a transparent light guide 29 and a fluorescent film 20 bonded to the first main surface 29 a of the transparent light guide 29. The fluorescent film 20 and the transparent light guide 29 are disposed in order from the incident side of the external light L. The first main surface 20 a of the fluorescent film 20 opposite to the transparent light guide 29 is a light incident surface of the light guide 28, and the first end surface 20 c of the fluorescent film 20 and the first end surface 29 c of the transparent light guide 29. Is a light exit surface of the light guide 28. The light receiving surface of the solar cell element 6 is disposed so as to face the first end surface 20c of the fluorescent film 20 and the first end surface 29c of the transparent light guide 29 which are light emitting surfaces.

The fluorescent film 20 converts part of the external light L (for example, sunlight) incident on the first main surface 20 a into fluorescence and radiates it toward the transparent light guide 29. A part of the fluorescence radiated from the fluorescent film 20 propagates through the fluorescent film 20 and the transparent light guide 29 while being totally reflected, and is a light emitting surface (first surface of the fluorescent film 20 having a smaller area than the light incident surface). It is led to the end face 20c and the first end face 29c) of the transparent light guide 29. The fluorescence emitted from the first end face 20c of the fluorescent film 20 and the first end face 29c of the transparent light guide 29 is incident on the solar cell element 6 and used for power generation.

The transparent light guide 29 is a transparent layer that does not contain a phosphor. However, unless the phosphor is intentionally dispersed for the purpose of wavelength conversion inside the transparent light guide 29, it is made of a material that contains some phosphor and is not completely transparent. Can also be used as the transparent light guide 29. Hereinafter, the base material 23 of the fluorescent film 20 may be referred to as a first transparent layer, and the transparent light guide 29 may be referred to as a second transparent layer.

FIG. 22 is a diagram showing the wavelength dispersion characteristics of the refractive index n1 of the first transparent layer 23 and the refractive index n2 of the second transparent layer 29. FIG.

In the first transparent layer 23, the peak of the absorption spectrum of at least one of the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c (hereinafter sometimes referred to as a specific phosphor). The wavelength is λ1, the peak wavelength of the emission spectrum of the third phosphor 8c is λ2, the refractive index of the first transparent layer 23 at the wavelength λ1 is n1 (λ1), and the refractive index of the first transparent layer 23 at the wavelength λ2 is When n1 (λ2) is set, n1 (λ1) and n1 (λ2) satisfy the relationship n1 (λ1) <n1 (λ2). In the wavelength region between the wavelength λ1 and the wavelength λ2, for example, the wavelength dispersion characteristic (abnormal dispersion) is shown such that the refractive index n1 increases as the wavelength λ increases. As the first transparent layer 23, a member exhibiting anomalous dispersion in a wide wavelength region including the wavelengths λ1 and λ2 is preferably used. As such a member, a member similar to that shown in the first embodiment can be used.

On the other hand, in the second transparent layer 29, when the refractive index of the second transparent layer 29 at the wavelength λ1 is n2 (λ1) and the refractive index of the second transparent layer 29 at the wavelength λ2 is n2 (λ2), n2 ( λ1) and n2 (λ2) satisfy the relationship of n2 (λ1) ≧ n2 (λ2) and n2 (λ2) ≧ n1 (λ2). In the wavelength region between the wavelength λ1 and the wavelength λ2, for example, a wavelength dispersion characteristic (normal dispersion) is shown such that the refractive index n2 decreases as the wavelength λ increases. Since a general transparent member exhibits such normal dispersion, a general known transparent member such as PMMA resin can be used as the second transparent layer 29.

In the solar cell module 27 of the present embodiment, the refractive index of the second transparent layer 29 shows normal dispersion. However, since n2 (λ2) is equal to or larger than n1 (λ2), the fluorescence emitted from the third phosphor 8c is surface-reflected at the interface between the first transparent layer 23 and the second transparent layer 29. It propagates in the inside of the 1st transparent layer 23 and the 2nd transparent layer 29, without. Since the fluorescence emitted from the third phosphor 8c is not confined in the first transparent layer 23 (fluorescent film 20), the light loss due to the self-absorption of the third phosphor 8c is reduced. In addition, since n1 indicates anomalous dispersion, at least light having the absorption wavelength of a specific phosphor can be efficiently taken into the inside of the fluorescent film 20, and the fluorescence emitted from the third phosphor 8c can be used without waste. It can lead to the battery element 6. Therefore, also in this embodiment, the solar cell module 27 capable of efficiently generating power is provided. In this case, when the peak wavelength of the absorption spectrum of any phosphor among the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c is λ1, n1 (λ1) and n2 (λ1) are If the relationship of n1 (λ1) <n1 (λ2) is satisfied, light having an absorption wavelength of all phosphors can be taken into the fluorescent film 20 efficiently, and more efficient power generation becomes possible. .

[Seventh Embodiment]
FIG. 23 is a cross-sectional view of the solar cell module 50 of the seventh embodiment. The configuration other than the light guide 51 is the same as that of the solar cell module 18 of the fourth embodiment. Therefore, here, the configuration of the light guide 51 will be mainly described. Moreover, about the structure which is common in the solar cell module 18 of 4th Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

The light guide 51 includes a transparent light guide 53, a fluorescent film 52 bonded to the first main surface 53a of the transparent light guide 53, a transparent protective film 21 covering the first main surface 52a of the fluorescent film 52, It has. The transparent protective film 21, the fluorescent film 52, and the transparent light guide 53 are disposed in order from the incident side of the external light L. The first main surface 21a of the transparent protective film 21 opposite to the fluorescent film 52 is a light incident surface of the light guide 51, the first end surface 21c of the transparent protective film 21, the first end surface 52c of the fluorescent film 52, and the transparent film. The first end surface 53 c of the light guide 53 is a light exit surface of the light guide 51. The light receiving surface of the solar cell element 6 is disposed so as to face the first end surface 21c of the transparent protective film 21, the first end surface 52c of the fluorescent film 52, and the first end surface 53c of the transparent light guide 53, which are light emission surfaces. Yes.

The fluorescent film 52 includes a transparent base material 54 that does not contain a fluorescent material, and a plurality of optical functional materials dispersed in the base material 54 (in FIG. 23, the first fluorescent material 8a, the second fluorescent material 8b, and the third fluorescent material). Phosphor 8c). The fluorescent film 52 converts part of the external light L (for example, sunlight) incident on the first main surface 52 a into fluorescence and radiates it toward the transparent light guide 53 and the transparent protective film 21. A part of the fluorescence emitted from the fluorescent film 52 propagates while totally reflecting inside the transparent protective film 21, the fluorescent film 52, and the transparent light guide 53, and is a light emitting surface (transparent) having a smaller area than the light incident surface. The first end face 21 c of the protective film 21, the first end face 52 c of the fluorescent film 52, and the first end face 53 c of the transparent light guide 53). The fluorescence emitted from the first end surface 21c of the transparent protective film 21, the first end surface 52c of the fluorescent film 52, and the first end surface 53c of the transparent light guide 53 is incident on the solar cell element 6 and used for power generation.

The transparent protective film 21, the base material 54, and the transparent light guide 53 are transparent layers that do not contain a phosphor.
However, if the phosphor is not intentionally dispersed for the purpose of wavelength conversion inside the transparent protective film 21, the phosphor film 52, and the transparent light guide 53, it contains some phosphor and is not completely transparent. Even those made of materials can be used as the transparent protective film 21, the base material 54, and the transparent light guide 53. Hereinafter, the base 54 of the fluorescent film 52 may be referred to as a first transparent layer, the transparent protective film 21 may be referred to as a second transparent layer, and the transparent light guide 53 may be referred to as a third transparent layer.

FIG. 24 is a diagram showing the wavelength dispersion characteristics of the refractive index n1 of the first transparent layer 54, the refractive index n2 of the second transparent layer 21, and the refractive index n3 of the third transparent layer 53. In the present embodiment, the first transparent layer 54 and the third transparent layer 53 are formed of the same material, and the refractive indexes n1 and n3 of the first transparent layer 54 and the third transparent layer 53 exhibit the same wavelength dispersion characteristics. .

In the second transparent layer 21, the peak wavelength of the absorption spectrum of at least one of the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c (hereinafter sometimes referred to as a specific phosphor). Is λ1, the peak wavelength of the emission spectrum of the third phosphor 8c is λ2, the refractive index of the second transparent layer 21 at the wavelength λ1 is n2 (λ1), and the refractive index of the second transparent layer 21 at the wavelength λ2 is n2. When (λ2), n2 (λ1) and n2 (λ2) satisfy the relationship n2 (λ1) <n2 (λ2). In the wavelength region between the wavelength λ1 and the wavelength λ2, for example, the wavelength dispersion characteristic (abnormal dispersion) is shown such that the refractive index n2 increases as the wavelength λ increases. As the second transparent layer 21, a member exhibiting anomalous dispersion in a wide wavelength region including the wavelengths λ1 and λ2 is preferably used. As such a member, a member similar to that shown in the first embodiment can be used.

On the other hand, in the first transparent layer 54 and the third transparent layer 53, the refractive index of the first transparent layer 54 at the wavelength λ1 is n1 (λ1), and the refractive index of the third transparent layer 53 at the wavelength λ1 is n3 (λ1). When the refractive index of the first transparent layer 54 at the wavelength λ2 is n1 (λ2) and the refractive index of the third transparent layer 53 at the wavelength λ2 is n3 (λ2), n1 (λ1), n1 (λ2), n3 (λ1) and n3 (λ2) are n1 (λ1) ≧ n1 (λ2), n3 (λ1) ≧ n3 (λ2), n2 (λ2) ≧ n1 (λ2), and n2 (λ2) ≧ n3 ( λ2) is satisfied. In the wavelength region between the wavelengths λ1 and λ2, for example, wavelength dispersion characteristics (normal dispersion) are shown such that the refractive indexes n1 and n3 decrease as the wavelength λ increases. Since general transparent members exhibit such normal dispersion, general known transparent members such as PMMA resin can be used as the first transparent layer 54 and the third transparent layer 53.

In the solar cell module 50 of the present embodiment, the refractive indexes of the first transparent layer 54 and the third transparent layer 53 indicate normal dispersion. However, since n2 (λ2) is the same as or larger than n1 (λ2) and n3 (λ2) is the same as n1 (λ2), the fluorescence emitted from the third phosphor 8c is the first transparent The first transparent layer 54, the second transparent layer 21, and the third transparent layer 53 are not surface-reflected at the interface between the layer 54 and the second transparent layer 21 and at the interface between the first transparent layer 54 and the third transparent layer 53. Propagate inside. Since the fluorescence emitted from the third phosphor 8c is not confined in the first transparent layer 54 (fluorescence film 52), the light loss due to the self-absorption of the third phosphor 8c is reduced.

Further, since n2 indicates anomalous dispersion, at least light having an absorption wavelength of the specific phosphor can be efficiently taken into the second transparent layer 21. Since n2 (λ1) takes a value between the refractive index outside the light guide (for example, the refractive index of air) n0 and n1 (λ1), the external light taken into the second transparent layer 21 is Compared with the case where external light is directly incident on the first transparent layer 54 from the outside of the light guide without passing through the second transparent layer 21, the light is taken into the first transparent layer 54 with less loss due to surface reflection. .

As described above, also in this embodiment, the light having the absorption wavelength of the specific phosphor can be efficiently taken into the fluorescent film 52, and the fluorescence emitted from the third phosphor 8c can be used without waste. It can be led to the element 6. Therefore, the solar cell module 50 capable of generating power efficiently is provided. In this case, when the peak wavelength of the absorption spectrum of any phosphor among the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c is λ1, n1 (λ1), n2 (λ1), n3 If (λ1), n1 (λ2), n2 (λ2), and n3 (λ2) satisfy the relationship of n2 (λ1) <n2 (λ2), the light having the absorption wavelength of all phosphors is efficiently emitted. It can be taken into the fluorescent film 20 and more efficient power generation becomes possible.

[Modification of the seventh embodiment]
FIGS. 25A to 27C are diagrams showing modifications of the wavelength dispersion characteristics of n1, n2, and n3.

In FIG. 24, the first transparent layer 54 and the third transparent layer 53 are formed of the same material, but the first transparent layer 54 and the third transparent layer 53 are not necessarily formed of the same material. Hereinafter, variations of the wavelength dispersion characteristics of n1, n2, and n3 will be described.

25A to 25C are examples in which n2 indicates anomalous dispersion and n1 and n3 indicate normal dispersion, as in FIG. In the example of FIGS. 25A to 25C, the first transparent layer 54 and the third transparent layer 53 are formed of different materials, and the wavelength dispersion characteristics of n1 and n3 do not necessarily match. Further, n1 (λ2) and n3 (λ2) do not necessarily satisfy the relationship of n2 (λ2) ≧ n1 (λ2) or n2 (λ2) ≧ n3 (λ2). In order to efficiently capture the fluorescence emitted from the phosphor into the second transparent layer 21 and the third transparent layer 53, the relationship of n2 (λ2) ≧ n1 (λ2) or n3 (λ2) ≧ n1 (λ2) is satisfied. It is preferable. However, even if the relationship of n2 (λ2) <n1 (λ2) or n3 (λ2) <n1 (λ2) is satisfied, n1 (λ2) and n3 (λ2) are sufficiently close to n2 (λ2). For example, the surface reflection at the interface between the first transparent layer 54 and the second transparent layer 21 and the interface between the first transparent layer 54 and the third transparent layer 53 can be reduced.

26A to 26C are examples in which n1 and n2 indicate anomalous dispersion and n3 indicates normal dispersion. In the example of FIGS. 26A to 26C, the first transparent layer 54 and the second transparent layer 21 may be formed of the same material, or may be formed of different materials. In the example of FIGS. 26A to 26C, n1 (λ2) and n3 (λ2) do not necessarily satisfy the relationship of n2 (λ2) ≧ n1 (λ2) or n2 (λ2) ≧ n3 (λ2). In order to efficiently capture the fluorescence emitted from the phosphor into the second transparent layer 21 and the third transparent layer 53, the relationship of n2 (λ2) ≧ n1 (λ2) or n3 (λ2) ≧ n1 (λ2) is satisfied. It is preferable. However, even if the relationship of n2 (λ2) <n1 (λ2) or n3 (λ2) <n1 (λ2) is satisfied, n1 (λ2) and n3 (λ2) are sufficiently close to n2 (λ2). For example, the surface reflection at the interface between the first transparent layer 54 and the second transparent layer 21 and the interface between the first transparent layer 54 and the third transparent layer 53 can be reduced. In the examples of FIGS. 26A to 26C, since both n1 and n2 exhibit anomalous dispersion, the refractive index difference between n1 (λ1) and n2 (λ1) and the refractive index difference between n1 (λ2) and n2 (λ2) are small. Easy to be. Therefore, the light having the absorption wavelength of the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c can be efficiently taken into the fluorescent film 52, and the fluorescence emitted from the third phosphor 8c. Can be propagated across the first transparent layer 54 and the second transparent layer 21.

27A to 27C are examples in which n1, n2, and n3 all exhibit anomalous dispersion. In the example of FIGS. 27A to 27C, the first transparent layer 54, the second transparent layer 21, and the third transparent layer 53 are formed of different materials, and the wavelength dispersion characteristics of these refractive indexes do not necessarily match. 27A to 27C, n1 (λ2) and n3 (λ2) do not necessarily satisfy the relationship of n2 (λ2) ≧ n1 (λ2) or n2 (λ2) ≧ n3 (λ2). In order to efficiently capture the fluorescence emitted from the phosphor into the second transparent layer 21 and the third transparent layer 53, the relationship of n2 (λ2) ≧ n1 (λ2) or n3 (λ2) ≧ n1 (λ2) is satisfied. It is preferable. However, even if the relationship of n2 (λ2) <n1 (λ2) or n3 (λ2) <n1 (λ2) is satisfied, n1 (λ2) and n3 (λ2) are sufficiently close to n2 (λ2). For example, the surface reflection at the interface between the first transparent layer 54 and the second transparent layer 21 and the interface between the first transparent layer 54 and the third transparent layer 53 can be reduced. In the examples of FIGS. 27A to 27C, since n1, n2, and n3 all exhibit anomalous dispersion, the refractive index difference between n1 (λ1), n2 (λ1), and n3 (λ1), n1 (λ2), n2 (λ2 ) And n3 (λ2) tend to be small in refractive index difference. Therefore, the light having the absorption wavelength of the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c can be efficiently taken into the fluorescent film 52, and the fluorescence emitted from the third phosphor 8c. Can be propagated across the first transparent layer 54, the second transparent layer 21, and the third transparent layer 53.

In the seventh embodiment and its modifications, a plurality of types of optical functional materials (for example, the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c) are included in the light guide. Although an example is shown, this configuration is an example, and a plurality of types of optical functional materials are not necessarily dispersed. A configuration in which only one type of optical functional material (for example, phosphor 8) is dispersed as in the first embodiment and the second embodiment can also be applied to the seventh embodiment and its modifications. In that case, the same effect as described above can be obtained.

[Eighth Embodiment]
FIG. 28 is a cross-sectional view of the solar cell module 55 of the eighth embodiment. The configuration other than the light guide 56 is the same as that of the solar cell module 50 of the seventh embodiment. Therefore, here, the configuration of the light guide 56 will be mainly described. Moreover, about the structure which is common in the solar cell module 50 of 7th Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

The light guide 56 includes a fluorescent film 52, a transparent light guide 57 bonded to the first main surface 52a of the fluorescent film 52, a transparent protective film 21 covering the first main surface 57a of the transparent light guide 57, It has. The transparent protective film 21, the transparent light guide 57, and the fluorescent film 52 are disposed in order from the incident side of the external light L. The first main surface 21 a opposite to the transparent light guide 57 of the transparent protective film 21 is a light incident surface of the light guide 56, the first end face 21 c of the transparent protective film 21, and the first surface of the transparent light guide 57. The end surface 57 c and the first end surface 52 c of the fluorescent film 52 are light emission surfaces of the light guide 56. The light receiving surface of the solar cell element 6 is disposed so as to oppose the first end surface 21c of the transparent protective film 21, the first end surface 57c of the transparent light guide 57, and the first end surface 52c of the fluorescent film 52, which are light emitting surfaces. Yes.

The light guide 56 of the present embodiment is that the transparent light guide 57 is configured as a film-shaped light guide, and is disposed between the fluorescent film 52 and the transparent protective film 21 in the seventh embodiment. Different from the light guide 51.

The transparent protective film 21, the transparent light guide 57, and the base material 54 are transparent layers that do not contain a phosphor.
However, if the phosphor is not intentionally dispersed for the purpose of wavelength conversion inside the transparent protective film 21, the transparent light guide 57 and the phosphor film 52, it contains some phosphor and is not completely transparent. Even those made of materials can be used as the transparent protective film 21, the transparent light guide 57 and the substrate 54. Hereinafter, the base 54 of the fluorescent film 52 may be referred to as a first transparent layer, the transparent protective film 21 may be referred to as a second transparent layer, and the transparent light guide 57 may be referred to as a third transparent layer.

FIG. 29 is a diagram showing the wavelength dispersion characteristics of the refractive index n1 of the first transparent layer 54, the refractive index n2 of the second transparent layer 21, and the refractive index n3 of the third transparent layer 57. In the present embodiment, the first transparent layer 54 and the third transparent layer 57 are formed of the same material, and the refractive indexes n1 and n3 of the first transparent layer 54 and the third transparent layer 57 exhibit the same wavelength dispersion characteristics. .

On the other hand, in the first transparent layer 54 and the third transparent layer 57, the refractive index of the first transparent layer 54 at the wavelength λ1 is n1 (λ1), and the refractive index of the third transparent layer 57 at the wavelength λ1 is n3 (λ1). When the refractive index of the first transparent layer 54 at the wavelength λ2 is n1 (λ2) and the refractive index of the third transparent layer 57 at the wavelength λ2 is n3 (λ2), n1 (λ1), n1 (λ2), n3 (λ1) and n3 (λ2) are n1 (λ1) ≧ n1 (λ2), n3 (λ1) ≧ n3 (λ2), n2 (λ2) ≧ n1 (λ2), and n2 (λ2) ≧ n3 ( λ2) is satisfied. In the wavelength region between the wavelengths λ1 and λ2, for example, wavelength dispersion characteristics (normal dispersion) are shown such that the refractive indexes n1 and n3 decrease as the wavelength λ increases. Since a general transparent member exhibits such normal dispersion, a general known transparent member such as PMMA resin can be used as the first transparent layer 54 and the third transparent layer 57.

Also in the solar cell module 55 of the present embodiment, since n2 (λ2) is the same as or larger than n1 (λ2) and n3 (λ2) is the same as n1 (λ2), the third phosphor 8c The emitted fluorescence is not surface-reflected at the interface between the first transparent layer 54 and the third transparent layer 57 and at the interface between the third transparent layer 57 and the second transparent layer 21, and the first transparent layer 54 and the second transparent layer. It propagates inside the layer 21 and the third transparent layer 57. Since the fluorescence emitted from the third phosphor 8c is not confined in the first transparent layer 54 (fluorescence film 52), the light loss due to the self-absorption of the third phosphor 8c is reduced.

Further, since n2 indicates anomalous dispersion, at least light having an absorption wavelength of the specific phosphor can be efficiently taken into the second transparent layer 21. Since n2 (λ1) takes a value between the refractive index outside the light guide (for example, the refractive index of air) n0 and n3 (λ1), the external light taken into the second transparent layer 21 is Compared to the case where external light is directly incident on the third transparent layer 57 from the outside of the light guide without passing through the second transparent layer 21, the light is taken into the third transparent layer 57 with less loss due to surface reflection. . Further, the external light taken into the third transparent layer 57 is reflected on the surface at the interface between the third transparent layer 57 and the first transparent layer 54 because n3 (λ1) and n1 (λ1) are the same. Without being taken into the first transparent layer 54.

Therefore, also in the present embodiment, the light having the absorption wavelength of the specific phosphor can be efficiently taken into the fluorescent film 52, and the fluorescence emitted from the third phosphor 8c can be used without waste. Can lead to. Therefore, the solar cell module 55 capable of generating power efficiently is provided. In this case, when the peak wavelength of the absorption spectrum of any phosphor among the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c is λ1, n1 (λ1), n2 (λ1), n3 If (λ1), n1 (λ2), n2 (λ2), and n3 (λ2) satisfy the relationship of n2 (λ1) <n2 (λ2), the light having the absorption wavelength of all phosphors is efficiently emitted. It can be taken into the fluorescent film 20 and more efficient power generation becomes possible.

[Modification of Eighth Embodiment]
FIG. 30A to FIG. 32C are diagrams showing modifications of the wavelength dispersion characteristics of n1, n2, and n3.

In FIG. 29, the first transparent layer 54 and the third transparent layer 57 are formed of the same material, but the first transparent layer 54 and the third transparent layer 57 are not necessarily formed of the same material. Hereinafter, variations of the wavelength dispersion characteristics of n1, n2, and n3 will be described.

30A to 30C are examples in which the refractive index n2 indicates anomalous dispersion and n1 and n3 indicate normal dispersion, as in FIG. In the example of FIGS. 30A to 30C, the first transparent layer 54 and the third transparent layer 57 are formed of different materials, and the wavelength dispersion characteristics of n1 and n3 do not necessarily match. Further, n1 (λ2) and n3 (λ2) do not necessarily satisfy the relationship of n2 (λ2) ≧ n1 (λ2) or n2 (λ2) ≧ n3 (λ2). In order to efficiently incorporate the fluorescence emitted from the phosphor into the second transparent layer 21 and the third transparent layer 57, the relationship of n3 (λ2) ≧ n1 (λ2) or n2 (λ2) ≧ n3 (λ2) is satisfied. It is preferable. However, even if the relationship of n3 (λ2) <n1 (λ2) or n2 (λ2) <n3 (λ2) is satisfied, n1 (λ2) and n3 (λ2) are sufficiently close to n2 (λ2). For example, surface reflection at the interface between the first transparent layer 54 and the third transparent layer 57 and at the interface between the third transparent layer 57 and the second transparent layer 21 can be reduced.

31A to 31C are examples in which n2 and n3 indicate anomalous dispersion and n1 indicates normal dispersion. In the example of FIGS. 31A to 31C, the third transparent layer 57 and the second transparent layer 21 may be formed of the same material, or may be formed of different materials. In the examples of FIGS. 31A to 31C, n1 (λ2) and n3 (λ2) do not necessarily satisfy the relationship of n2 (λ2) ≧ n1 (λ2) or n2 (λ2) ≧ n3 (λ2). In order to efficiently incorporate the fluorescence emitted from the phosphor into the second transparent layer 21 and the third transparent layer 57, the relationship of n3 (λ2) ≧ n1 (λ2) or n2 (λ2) ≧ n3 (λ2) is satisfied. It is preferable. However, even if the relationship of n3 (λ2) <n1 (λ2) or n2 (λ2) <n3 (λ2) is satisfied, n1 (λ2) and n3 (λ2) are sufficiently close to n2 (λ2). For example, surface reflection at the interface between the first transparent layer 54 and the third transparent layer 57 and at the interface between the third transparent layer 57 and the second transparent layer 21 can be reduced. In the examples of FIGS. 31A to 31C, since n2 and n3 both exhibit anomalous dispersion, the refractive index difference between n2 (λ1) and n3 (λ1) and the refractive index difference between n2 (λ2) and n3 (λ2) are small. Easy to be. Therefore, the light having the absorption wavelength of the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c can be efficiently taken into the fluorescent film 52, and the fluorescence emitted from the third phosphor 8c. Can be propagated across the second transparent layer 21 and the third transparent layer 57.

32A to 32C are examples in which n1, n2, and n3 all show anomalous dispersion. In the example of FIGS. 32A to 32C, the first transparent layer 54, the second transparent layer 21, and the third transparent layer 57 are formed of different materials, and the wavelength dispersion characteristics of these refractive indexes do not necessarily match. In the example of FIGS. 32A to 32C, n1 (λ2) and n3 (λ2) do not necessarily satisfy the relationship of n2 (λ2) ≧ n1 (λ2) or n2 (λ2) ≧ n3 (λ2). In order to efficiently incorporate the fluorescence emitted from the phosphor into the second transparent layer 21 and the third transparent layer 57, the relationship of n3 (λ2) ≧ n1 (λ2) or n2 (λ2) ≧ n3 (λ2) is satisfied. It is preferable. However, even if n3 (λ2) <n1 (λ2) or n2 (λ2) <n3 (λ2) is satisfied, n1 (λ2) and n3 (λ2) are sufficiently close to n2 (λ2). For example, surface reflection at the interface between the first transparent layer 54 and the third transparent layer 57 and at the interface between the third transparent layer 57 and the second transparent layer 21 can be reduced. In the examples of FIGS. 32A to 32C, since n1, n2, and n3 all exhibit anomalous dispersion, the refractive index difference between n1 (λ1), n2 (λ1), and n3 (λ1), n1 (λ2), n2 (λ2 ) And n3 (λ2) tend to be small in refractive index difference. Therefore, the light having the absorption wavelength of the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c can be efficiently taken into the fluorescent film 52, and the fluorescence emitted from the third phosphor 8c. Can be propagated across the first transparent layer 54, the second transparent layer 21, and the third transparent layer 57.

30A to 32C, it is preferable that n3 (λ1), n2 (λ1), and n1 (λ1) satisfy the relationship of n2 (λ1) ≦ n3 (λ1) ≦ n1 (λ1). Thereby, the surface reflection at the interface between the first transparent layer 54 and the third transparent layer 57 and the interface between the third transparent layer 57 and the second transparent layer 21 can be reduced, and the first phosphor 8a and the second phosphor. The light having the absorption wavelength of 8b and the third phosphor 8c can be efficiently taken into the fluorescent film 52.

In the eighth embodiment and its modification, a plurality of types of optical functional materials (for example, the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c) are included in the light guide. Although an example is shown, this configuration is an example, and a plurality of types of optical functional materials are not necessarily dispersed. A configuration in which only one type of optical functional material (for example, phosphor 8) is dispersed as in the first embodiment and the second embodiment can also be applied to the eighth embodiment and its modifications. In that case, the same effect as described above can be obtained.

[Ninth Embodiment]
FIG. 33 is a schematic diagram of the solar cell module 32 of the ninth embodiment. In the solar cell module 32, the shape and arrangement of the light guide 30 and the solar cell element 31 are different from those of the solar cell module 16 of the third embodiment. Therefore, here, the shape and arrangement of the light guide 30 and the solar cell element 31 will be described, and detailed description of the other configurations will be omitted.

In the solar cell module 32, the light guide 30 is configured as a curved plate-like member, and the solar cell element 31 emits light emitted from the curved first end surface 30c of the light guide 30 that is a light emission surface. It is configured to receive light. The light guide 30 has, for example, a shape in which a plate-like member having a constant thickness is curved around an axis parallel to the Y axis. Of the first main surface 30a and the second main surface 30b of the light guide 30, the first main surface 30a that is curved outwardly is a light incident surface on which external light (for example, sunlight) L is incident.

The light L incident on the light incident surface 30 a is absorbed by a plurality of optical functional materials (not shown) dispersed inside the light guide 30. Then, energy transfer due to the Forster mechanism occurs between the plurality of optical functional materials, and light emitted from the optical functional material having the largest peak wavelength of the emission spectrum is a light emitting surface 30c having a smaller area than the light incident surface 30a. It is condensed and ejected. As the plurality of optical functional materials dispersed inside the light guide 30, for example, the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c shown in FIGS. 9 to 13 are used. .

As the solar cell element 31, the same amorphous silicon solar cell as in the third embodiment is used. The solar cell element 31 is disposed with the light receiving surface facing the first end surface 30 c of the light guide 30. When the spectral sensitivities of the solar cell elements 31 at the peak wavelengths of the emission spectra of the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c are compared, a plurality of optical functional materials (first phosphor 8a, second fluorescence The spectral sensitivity of the solar cell element 31 at the peak wavelength of the emission spectrum of the optical functional material (third phosphor 8c) having the largest emission spectrum peak of the body 8b and the third phosphor 8c) It is larger than the spectral sensitivity of the solar cell element 31 at the peak wavelength of the emission spectrum of any of the other optical functional materials (the first phosphor 8a and the second phosphor 8b). Thereby, the solar cell module 32 with high power generation efficiency is provided.

In the solar cell module 32, the light incident surface 30a of the light guide 30 is a curved surface. Therefore, even when the incident angle of the light L changes along the bending direction of the light guide 30 depending on the time zone such as daytime and evening, the amount of power generation does not change greatly. Normally, when power is generated by a solar cell, a tracking device is provided so that the light receiving surface of the solar cell faces the incident direction of light, and the angle of the solar cell is controlled in two axial directions. When the light incident surface 30a of the light guide 30 is curved so as to face various directions as in the embodiment, there is no need to provide such a tracking device. Even if a tracking device is provided, only the angle control in the direction orthogonal to the bending direction is required, and therefore the configuration of the tracking device can be simplified as compared with the case where the angle control is performed in the biaxial direction. In the present embodiment, the light guide 30 has a shape curved in one direction, but the shape of the light guide 30 is not limited to this. For example, a dome shape such as a hemispherical shape or a bell shape may be used. In that case, no tracking device is required.

In the solar cell module 32, since the light guide 30 is curved, the light guide 30 can be installed on the wall or roof of a building formed in a curved shape. In the present embodiment, the light guide 30 has a shape curved in one direction, but the shape of the light guide 30 is not limited to such a simple shape. For example, it can be designed into a free shape such as a tile shape or a wavy shape.
Depending on the place where the light guide 30 is installed, it may have not only a curved shape but also a bent shape having a ridgeline. The curved surface or the bent surface may be provided on at least a part of the light incident surface, whereby the above-described effects can be obtained.

[Tenth embodiment]
FIG. 34 is a schematic diagram of the solar cell module 35 of the tenth embodiment. In the solar cell module 35, the shape and arrangement of the light guide 33 and the solar cell element 34 are different from those of the solar cell module 16 of the third embodiment. Therefore, here, the shape and arrangement of the light guide 33 and the solar cell element 34 will be described, and detailed description of the other components will be omitted.

In the solar cell module 35, the light guide 33 is configured as a cylindrical member having an axis parallel to the Y axis as a central axis, and the solar cell element 34 is a first end surface of the light guide 33 that is a light emission surface. It is configured to receive light emitted from 33c. The light guide 33 has, for example, a cylindrical shape with a constant thickness. The outer peripheral surface of the light guide 33 is a first main surface 33a, and the inner peripheral surface of the light guide 33 is a second main surface 33b. Of the first main surface 33a and the second main surface 33b of the light guide 33, the first main surface 33a that is curved outwardly is a light incident surface on which external light (for example, sunlight) L is incident.

The light L incident on the light incident surface 33 a is absorbed by a plurality of optical functional materials (not shown) dispersed inside the light guide 33. Then, energy transfer occurs due to the Forster mechanism between the plurality of optical functional materials, and the light emitted from the optical functional material having the largest peak wavelength of the emission spectrum has a light exit surface 33c having a smaller area than the light incident surface 33a. It is condensed and ejected. As the plurality of optical functional materials dispersed in the light guide 33, for example, the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c shown in FIGS. 9 to 13 are used. .

As the solar cell element 34, the same amorphous silicon solar cell as in the third embodiment is used. The solar cell element 34 is disposed with the light receiving surface facing the first end surface 33 c of the light guide 33. When the spectral sensitivities of the solar cell elements 34 at the peak wavelengths of the emission spectra of the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c are compared, a plurality of optical functional materials (first phosphor 8a, second fluorescence The spectral sensitivity of the solar cell element 34 at the peak wavelength of the emission spectrum of the optical functional material (third phosphor 8c) having the longest emission spectrum peak wavelength of the phosphor 8b and the third phosphor 8c) It is larger than the spectral sensitivity of the solar cell element 34 at the peak wavelength of the emission spectrum of any of the other optical functional materials (the first phosphor 8a and the second phosphor 8b). Thereby, the solar cell module 35 with high power generation efficiency is provided.

In the solar cell module 35, the light incident surface 33a of the light guide 33 is a curved surface. Therefore, even when the incident angle of the light L changes along the bending direction of the light guide 33 depending on the time zone such as daytime and evening, the amount of power generation does not change greatly. Moreover, since the light guide 33 is formed in a cylindrical shape, the light guide 33 can be installed on a pillar of a building, a utility pole, or the like. In the case of this embodiment, the light guide 33 is formed in a cylindrical shape, but the shape of the light guide 33 is not limited to such a shape, and a cross section cut by a plane parallel to the XZ plane is an ellipse or a polygon. For example, it can be designed in a free shape according to the place where the light guide 33 is installed.

[Eleventh embodiment]
FIG. 35 is a schematic diagram of the solar cell module 38 of the eleventh embodiment. In the solar cell module 38, the shape and arrangement of the light guide 36 and the solar cell element 37 are different from those of the solar cell module 16 of the third embodiment. Therefore, here, the shape and arrangement of the light guide 36 and the solar cell element 37 will be described, and detailed description of other configurations will be omitted.

In the solar cell module 38, the light guide 36 is configured as a columnar member extending in the Y direction, and the solar cell element 37 receives light emitted from the first end surface 36c of the light guide 36 that is a light emission surface. Is configured to do. The light guide 36 has, for example, a cylindrical shape whose central axis is an axis parallel to the Y axis. The outer peripheral surface of the light guide 36 is a first main surface 36a, and the first main surface 36a is a light incident surface on which external light (for example, sunlight) L is incident.

As the solar cell element 37, the same amorphous silicon solar cell as in the third embodiment is used. The solar cell element 37 is disposed with the light receiving surface facing the first end surface 36 c of the light guide 36. When the spectral sensitivities of the solar cell elements 37 at the peak wavelengths of the emission spectra of the first phosphor 8a, the second phosphor 8b, and the third phosphor 8c are compared, a plurality of optical functional materials (first phosphor 8a, second fluorescence The spectral sensitivity of the solar cell element 37 at the peak wavelength of the emission spectrum of the optical functional material (third phosphor 8c) having the longest emission spectrum peak wavelength is the light guide 36. It is larger than the spectral sensitivity of the solar cell element 37 at the peak wavelength of the emission spectrum of any other optical functional material (the first phosphor 8a and the second phosphor 8b). Thereby, the solar cell module 38 with high power generation efficiency is provided.

In FIG. 35, eight unit units 39 each including the light guide 36 and the solar cell element 37 are disposed adjacent to each other in the X direction, but the number of unit units 39 is not limited to this.
The number of unit units 39 may be one set or a plurality of sets other than eight sets. When a plurality of unit units 39 are provided, they can be installed on a flat surface. When a plurality of sets of unit units 39 are flexibly connected by a string-like connecting member 40, they can be freely changed in shape on a curved surface that is not flat and can be deployed when necessary, such as a basket. It is possible to make adjustments such as winding and storing when not needed. Further, when a plurality of sets of unit units 39 are connected with a hard rod-like connecting member 40 at an interval, the wind passes through the space between the light guides 36, so that the wind pressure can be reduced. Installation of the battery module stand is simplified.

In the case of the present embodiment, the light guide 36 is formed in a cylindrical shape, but the shape of the light guide 36 is not limited to such a shape, and a cross section cut by a plane parallel to the XZ plane is an ellipse or It can be designed in a free shape such as a polygon according to the place where the light guide 36 is installed.

In the solar cell module 38, the light incident surface 36a of the light guide 36 is a curved surface. Therefore, even when the incident angle of the light L changes along the bending direction of the light guide 36 depending on the time zone such as daytime and evening, the power generation amount does not change greatly. In addition, since the light guide 36 is formed in a columnar shape, by arranging a plurality of light guides 36 and flexibly connecting them, it is possible to install on a curved surface as well as on a plane. A configuration capable of unfolding / winding can be realized.

[Solar power generator]
FIG. 36 is a schematic configuration diagram of the solar power generation device 1000.

The solar power generation apparatus 1000 includes a solar cell module 1001 that converts sunlight energy into electric power, an inverter (DC / AC converter) 1004 that converts DC power output from the solar cell module 1001 into AC power, A storage battery 1005 that stores DC power output from the battery module 1001.

The solar cell module 1001 includes a light guide body 1002 that collects sunlight, and a solar cell element 1003 that generates power using sunlight collected by the light guide body 1002.
As the solar cell module 1001, for example, the solar cell module described in the first to eleventh embodiments is used.

The solar power generation apparatus 1000 supplies power to the external electronic device 1006. The electronic device 1006 is supplied with power from the auxiliary power source 1007 as necessary.

Since the photovoltaic power generation apparatus 1000 includes the above-described solar cell module according to the present invention, the photovoltaic power generation apparatus 1000 has a high power generation efficiency.

The present invention can be used for a light guide, a solar cell module, and a solar power generation device.

DESCRIPTION OF SYMBOLS 1 ... Solar cell module, 4 ... Light guide, 5 ... Base material (1st transparent layer), 6 ... Solar cell element, 8, 8a, 8b, 8c ... Phosphor (optical functional material), 11 ... Solar cell module , 12 ... Light guide, 14 ... Transparent light guide (second transparent layer), 15 ... Base material (first transparent layer), 16 ... Solar cell module, 17 ... Light guide, 18 ... Solar cell module, 19 DESCRIPTION OF SYMBOLS ... Light guide, 21 ... Transparent protective film (2nd transparent layer), 22 ... Transparent light guide (3rd transparent layer), 23 ... Base material (1st transparent layer), 24 ... Solar cell module, 25 ... Guide Light body 26 ... Transparent light guide (second transparent layer), 27 ... Solar cell module, 28 ... Light guide, 29 ... Transparent light guide (second transparent layer), 30 ... Light guide, 30 ... Light Incident surface, 30c: Light exit surface, 31: Solar cell element, 32: Solar cell module, 33: Light guide, 33a: Light incident surface, 33c Light exit surface, 34 ... solar cell element, 35 ... solar cell module, 36 ... light guide, 36a ... light incident surface, 36c ... light exit surface, 37 ... solar cell element, 38 ... solar cell module, 39 ... unit , 40 ... connecting member, 50 ... solar cell module, 51 ... light guide, 53 ... transparent light guide (third transparent layer), 54 ... base material (first transparent layer), 55 ... solar cell module, 56 ... Light guide, 57 ... Transparent light guide (third transparent layer), 1000 ... Solar power generation device

Claims

A first transparent layer;
An optical functional material dispersed inside the first transparent layer,
The peak wavelength of the absorption spectrum of the optical functional material is λ1, the peak wavelength of the emission spectrum of the optical functional material is λ2, the refractive index of the first transparent layer at the wavelength λ1 is n1 (λ1), and the wavelength λ2 A light guide body in which n1 (λ1) and n1 (λ2) satisfy a relationship of n1 (λ1) <n1 (λ2), where n1 (λ2) is the refractive index of the first transparent layer.
A first transparent layer;
A plurality of types of optical functional materials dispersed inside the first transparent layer,
The peak wavelength of the absorption spectrum of any one of the plurality of types of optical functional materials is λ1, and the emission spectrum of the optical functional material having the largest emission spectrum peak wavelength among the plurality of types of optical functional materials. When the peak wavelength of λ2 is λ2, the refractive index of the first transparent layer at the wavelength λ1 is n1 (λ1), and the refractive index of the first transparent layer at the wavelength λ2 is n1 (λ2), the n1 A light guide body in which (λ1) and n1 (λ2) satisfy a relationship of n1 (λ1) <n1 (λ2).
When the peak wavelength of the emission spectrum of any optical functional material among the plurality of types of optical functional materials is λ1, n1 (λ1) and n1 (λ2) satisfy n1 (λ1) <n1 (λ2). The light guide according to claim 2 that satisfies the relationship.
The light guide according to claim 3, wherein energy transfer occurs between the plurality of types of optical functional materials, and light is emitted from the optical functional material having the largest peak wavelength of the emission spectrum.
A second transparent layer is provided on one side of the first transparent layer;
When the refractive index of the second transparent layer at the wavelength λ1 is n2 (λ1) and the refractive index of the second transparent layer at the wavelength λ2 is n2 (λ2), the n2 (λ1) and the n2 ( The light guide according to any one of claims 1 to 4, wherein λ2) satisfies a relationship of n2 (λ1) <n2 (λ2).
The light guide according to claim 5, wherein the n2 (λ2) and the n1 (λ2) satisfy a relationship of n2 (λ2) ≧ n1 (λ2).
A second transparent layer is provided on one side of the first transparent layer;
When the refractive index of the second transparent layer at the wavelength λ1 is n2 (λ1) and the refractive index of the second transparent layer at the wavelength λ2 is n2 (λ2), the n2 (λ1) and the n2 ( λ2) satisfies the relationship n2 (λ1)> n2 (λ2),
5. The light guide according to claim 1, wherein the n2 (λ2) and the n1 (λ2) satisfy a relationship of n2 (λ2) ≧ n1 (λ2).
A third transparent layer is provided on the other surface side of the first transparent layer;
The n3 (λ2) and the n1 (λ2) satisfy a relationship of n3 (λ2) ≧ n1 (λ2), where n3 (λ2) is a refractive index of the third transparent layer at the wavelength λ2. The light guide according to any one of 5 to 7.
A first transparent layer;
An optical functional material dispersed inside the first transparent layer;
A second transparent layer provided on one side of the first transparent layer,
The peak wavelength of the absorption spectrum of the optical functional material is λ1, the peak wavelength of the emission spectrum of the optical functional material is λ2, the refractive index of the second transparent layer at the wavelength λ1 is n2 (λ1), and the wavelength λ2 A light guide body in which n2 (λ1) and n2 (λ2) satisfy a relationship of n2 (λ1) <n2 (λ2), where n2 (λ2) is the refractive index of the second transparent layer.
A first transparent layer;
A plurality of types of optical functional materials dispersed in the first transparent layer;
A second transparent layer provided on one side of the first transparent layer,
The peak wavelength of the absorption spectrum of any one of the plurality of types of optical functional materials is λ1, and the emission spectrum of the optical functional material having the largest emission spectrum peak wavelength among the plurality of types of optical functional materials. When the peak wavelength of λ2 is λ2, the refractive index of the second transparent layer at the wavelength λ1 is n2 (λ1), and the refractive index of the second transparent layer at the wavelength λ2 is n2 (λ2), the n2 A light guide body in which (λ1) and n2 (λ2) satisfy a relationship of n2 (λ1) <n2 (λ2).
When the peak wavelength of the emission spectrum of an arbitrary optical functional material among the plural types of optical functional materials is λ1, the n2 (λ1) and the n2 (λ2) satisfy n2 (λ1) <n2 (λ2). The light guide according to claim 10 that satisfies the relationship.
The light guide according to claim 11, wherein energy transfer occurs between the plurality of types of optical functional materials, and light is emitted from the optical functional material having the largest peak wavelength of the emission spectrum.
When the refractive index of the first transparent layer at the wavelength λ1 is n1 (λ1) and the refractive index of the first transparent layer at the wavelength λ2 is n1 (λ2), the n1 (λ1) and the n1 ( The light guide according to any one of claims 9 to 12, wherein λ2) satisfies a relationship of n1 (λ1) <n1 (λ2).
When the refractive index of the first transparent layer at the wavelength λ1 is n1 (λ1) and the refractive index of the first transparent layer at the wavelength λ2 is n1 (λ2), the n1 (λ1) and the n1 ( The light guide according to any one of claims 9 to 12, wherein λ2) satisfies a relationship of n1 (λ1)> n1 (λ2).
The light guide according to claim 13 or 14, wherein the n2 (λ2) and the n1 (λ2) satisfy a relationship of n2 (λ2) ≧ n1 (λ2).
A third transparent layer is provided on the other surface side of the first transparent layer;
The n3 (λ2) and the n1 (λ2) satisfy a relationship of n3 (λ2) ≧ n1 (λ2), where n3 (λ2) is a refractive index of the third transparent layer at the wavelength λ2. The light guide according to any one of 9 to 15.
A third transparent layer is provided between the first transparent layer and the second transparent layer;
The n3 (λ2) and the n1 (λ2) satisfy a relationship of n3 (λ2) ≧ n1 (λ2), where n3 (λ2) is a refractive index of the third transparent layer at the wavelength λ2. The light guide according to any one of 9 to 15.
When the refractive index of the third transparent layer at the wavelength λ1 is n3 (λ1), the n3 (λ1), the n2 (λ1), and the n1 (λ1) are n2 (λ1) ≦ n3 (λ1) The light guide according to claim 17, satisfying a relationship of ≦ n1 (λ1).
A light guide according to any one of claims 1 to 18,
A solar cell module comprising: a solar cell element that receives light emitted from the light guide.
The solar cell module according to claim 19, wherein the light incident surface of the light guide is a flat surface.
The light guide is configured as a flat plate-shaped member,
The solar cell module according to claim 20, wherein the solar cell element receives the fluorescence emitted from an end surface of the light guide that is a light emission surface.
The solar cell module according to claim 19, wherein at least a part of the light incident surface of the light guide is a bent or curved surface.
The light guide is configured as a curved plate-shaped member,
The solar cell module according to claim 22, wherein the solar cell element receives the fluorescence emitted from an end surface of the light guide that is a light emission surface.
The light guide is configured as a cylindrical member,
The solar cell module according to claim 22, wherein the solar cell element receives the fluorescence emitted from an end surface of the light guide that is a light emission surface.
The light guide is configured as a columnar member,
The solar cell module according to claim 22, wherein the solar cell element receives the light emitted from an end surface of the light guide that is a light emission surface.
A plurality of unit units each including the light guide body and the solar cell element as a set are installed adjacent to each other, and the plurality of unit units are flexibly connected to each other by a string-like connecting member. The solar cell module according to 25.
26. The unit unit according to claim 25, wherein a plurality of unit units each including the light guide body and the solar cell element are installed adjacent to each other, and the plurality of unit units are connected to each other with a space therebetween. Solar cell module.
A solar power generation device comprising the solar cell module according to any one of claims 19 to 27.