JPWO2013069785A1 - Light guide, solar cell module and solar power generation device - Google Patents

Abstract

  The light guide 14 has a first main surface 14a and a first end surface 14c, includes at least one optical functional material 12, 18, and the at least one optical functional material emits light anisotropically. One optical functional material 12, configured to propagate at least light emitted from the first optical functional material and to emit the light from the end face, and the first optical functional material emits from the first optical functional material. The angle formed by the direction in which the emitted light has the highest intensity and the normal line of the first main surface is oriented so as to be equal to or greater than the critical angle.

Description

The present invention relates to a light guide, a solar cell module, and a solar power generation device.
This application claims priority based on Japanese Patent Application No. 2011-247470 filed in Japan on November 11, 2011 and Japanese Patent Application No. 2011-281502 filed in Japan on December 22, 2011. The contents are incorporated herein.

  2. Description of the Related Art There is known a solar power generation device that generates power by installing a solar cell element on an end surface of a light guide and making light propagated through the light guide enter the solar cell element.

  In patent document 1, it has the structure which propagates a part of sunlight which injected from one main surface of the light guide to the inside of a light guide, and guides it to a solar cell element. A phosphor is applied to the surface of the light guide, and the phosphor is excited by sunlight incident on the light guide. Light (fluorescence) emitted from the phosphor propagates through the light guide and enters the solar cell element to generate power.

  In patent document 2, it has the structure which propagates a part of sunlight which injected from one main surface of the light guide to the inside of a light guide, and guides it to a photoelectric conversion part. The finger s-directional luminescent particles are dispersed inside the light guide. Sunlight incident on the light guide is converted by the directional luminescent particles so as to have directivity in the direction of the photoelectric conversion unit.

JP-A-3-273686 JP 2010-225692 A

In patent document 1, the sunlight used for excitation of a fluorescent substance is very little of the sunlight which injects into a light guide. Most of the sunlight incident on the light guide is transmitted through the light guide and does not contribute to power generation.
In patent document 2, it is the structure by which the sunlight which injected into the light guide is converted with one kind of directional light-emitting particle. Therefore, the wavelength range that can be used for power generation is limited.
In Patent Document 2, the directivity (anisotropy) of emitted light is used. However, this configuration has an effect of absorption directivity, and incident light having an angle close to vertical is transmitted.
Therefore, in these patent documents 1 and 2, a solar power generation device with high power generation efficiency cannot be provided.

The objective in the aspect of this invention is providing the light guide with high extraction efficiency of light, the solar cell module with high power generation efficiency, and a solar power generation device using the same.
Another object of the present invention is to provide a solar cell module having high light extraction efficiency and high power generation efficiency, and a solar power generation apparatus using the solar cell module.

  The light guide in one aspect of the present invention has a first main surface and a first end surface, includes at least one optical functional material, and the at least one optical functional material emits light anisotropically. A first optical functional material configured to propagate at least light emitted from the first optical functional material and emit the light from the end face, and the first optical functional material is emitted from the first optical functional material. The orientation is such that the angle formed between the direction of maximum light emission intensity and the normal line of the first main surface is greater than or equal to the critical angle.

  In the light guide according to an aspect of the present invention, the first optical functional material may absorb a part of external light incident from the first main surface.

  The light guide in one embodiment of the present invention may further include a second optical functional material that isotropically absorbs part of incident external light.

  In the light guide in one embodiment of the present invention, the second optical functional material has a property of absorbing light isotropically or has a property of absorbing light anisotropically. Any of the optical functional materials in a random state that is difficult to be oriented with respect to the contained material may be used.

  The light guide in one aspect of the present invention may include a plurality of the optical functional materials, and the first optical functional material may include an optical functional material having a maximum emission spectrum peak wavelength among the plurality of optical functional materials. .

  In the light guide according to the aspect of the present invention, the first optical functional material has a direction in which the emission intensity of the light emitted from the first optical functional material is the largest when viewed from the normal direction of the first main surface. You may orientate so that it may face the said end surface.

  In the light guide according to one aspect of the present invention, the first optical functional material may include an optical functional material made of a dichroic fluorescent dye.

  In the light guide in one embodiment of the present invention, the dichroic fluorescent dye may include a positive dichroic fluorescent dye in which the direction orthogonal to the molecular long axis is the direction with the highest emission intensity.

  The light guide in one aspect of the present invention may further include a diffusion plate that is provided on the first main surface side and diffuses external light incident from the outside of the light guide.

The light guide in one embodiment of the present invention causes energy transfer by a Forster mechanism between the plurality of optical functional materials, and emits light emitted from the optical functional material having the largest peak wavelength of the emission spectrum. You may inject from one end surface.

  In the light guide according to an aspect of the present invention, among the plurality of optical functional materials, one or a plurality of optical functional materials other than the optical functional material having the largest peak wavelength of the emission spectrum has a fluorescence quantum yield of 80. % Or less of optical functional material may be included.

  In the light guide in one aspect of the present invention, the fluorescence quantum yield of the optical functional material having the largest peak wavelength of the emission spectrum is greater than the fluorescence quantum yield of any other optical functional material included in the light guide. May be higher.

  In the light guide in one embodiment of the present invention, the optical functional material may include an optical functional material made of an inorganic material.

  In the light guide in one embodiment of the present invention, the optical functional material made of the inorganic material may include an optical functional material made of quantum dots.

  In the light guide in one embodiment of the present invention, the optical functional material may include an optical functional material made of an organic-inorganic hybrid phosphor.

  The light guide in one embodiment of the present invention may further include a reflective layer that reflects light propagating through the light guide.

  In the light guide according to the aspect of the present invention, the reflection layer may be a scattering reflection layer that scatters and reflects incident light.

  The light guide in one embodiment of the present invention may further include a retardation plate between the light guide and the reflective layer.

  In the light guide according to the aspect of the present invention, the retardation plate may be a ¼λ plate.

  The light guide in one aspect of the present invention may include a transparent light guide and the plurality of optical functional materials dispersed inside the transparent light guide.

  The light guide in one aspect of the present invention is provided on the third main surface of the transparent light guide and the transparent light guide, and the optical functional material layer in which the plurality of optical functional materials are dispersed, May be included.

  The light guide in one aspect of the present invention may further include a peelable pressure-sensitive adhesive layer, and the transparent light guide and the optical functional material layer may be bonded with the pressure-sensitive adhesive layer.

  A solar cell module according to another aspect of the present invention includes a light guide and a first solar cell element that receives the light emitted from the first end face of the light guide.

  In the solar cell module according to another aspect of the present invention, the spectral sensitivity of the first solar cell element at the peak wavelength of the emission spectrum of the optical functional material having the largest emission spectrum peak wavelength among the optical functional materials is the light guide. It may be larger than the spectral sensitivity of the first solar cell element at the peak wavelength of the emission spectrum of any other optical functional material provided in the body.

  The solar cell module according to another aspect of the present invention further includes a third main surface and a second end surface, is disposed on the second main surface side, and transmits light transmitted from the second main surface to the third main surface. A second light guide that is incident from the surface, propagates, and exits from the second end face; and a second solar cell element that is provided on the second end face and receives light emitted from the second end face. You may prepare.

  In the light guide according to the aspect of the present invention, the second light guide has a fourth main surface facing the third main surface, and the second light guide propagates and is emitted from the end surface. Are reflected from the third main surface and emitted from the end surface, reflected from the fourth main surface and emitted from the end surface, and emitted from the end surface while being reflected between the third main surface and the fourth main surface. Or may be emitted from an end face without being incident on any of the third main surface and the fourth main surface.

  In the solar cell module according to another aspect of the present invention, the anisotropic light functional material has a direction in which the light emission intensity of light emitted from the anisotropic light functional material is the largest when viewed from the normal direction of the first main surface. It may be oriented to face the first end face.

  In the solar cell module according to another aspect of the present invention, the second light guide reflects and propagates light at an inclined surface provided on the fourth main surface, and is emitted from the second end surface. It may be a body.

  In the solar cell module according to another aspect of the present invention, a reflective layer that reflects light transmitted from the fourth main surface side of the second light guide on the fourth main surface side of the second light guide. May be provided.

  In the solar cell module according to another aspect of the present invention, the first solar cell element and the second solar cell element may be configured by a common solar cell element.

  The solar power generation device in the further another aspect of this invention is equipped with the said solar cell module.

  The light guide in still another aspect of the present invention has a first main surface and an end surface, includes a plurality of optical functional materials, and the plurality of optical functional materials emit at least light anisotropically. An optical functional material and a second optical functional material that absorbs light isotropically, and a part of the external light incident on the first main surface is absorbed by the plurality of optical functional materials, The light emitted from one optical functional material is propagated and emitted from the end face, and the first optical functional material has a direction in which the emission intensity of light emitted from the first optical functional material is highest and the It is oriented so that the angle formed with the normal line of the first main surface is not less than the critical angle.

  The light guide in still another aspect of the present invention has a second main surface facing the first main surface, and the propagation and emission from the end surface means that the light is reflected from the first main surface and is reflected from the end surface. Injecting, reflecting from the second main surface opposite to the first main surface and emitting from the end surface, emitting from the end surface while reflecting between the first main surface and the second main surface, or the Either of the first main surface and the second main surface may be emitted from the end surface without being incident.

  In the light guide according to still another aspect of the present invention, the second optical functional material is a material having the property of absorbing light isotropically or having the property of absorbing light anisotropically. Any of the optical functional materials in a random state that is difficult to be oriented with respect to the material included in the light body may be used.

  In the light guide according to still another aspect of the present invention, the first optical functional material may include an optical functional material having a peak wavelength of an emission spectrum that is the largest among the plurality of optical functional materials.

  In the light guide according to still another aspect of the present invention, the first optical functional material has the highest light emission intensity of light emitted from the first optical functional material when viewed from the normal direction of the first main surface. You may orientate so that a direction may face the said end surface.

  In the light guide according to still another aspect of the present invention, the first optical functional material may include an optical functional material made of a dichroic fluorescent dye.

  In the light guide in still another aspect of the present invention, the dichroic fluorescent dye may include a positive dichroic fluorescent dye in which the direction perpendicular to the molecular long axis is the direction with the highest emission intensity.

  The light guide in still another aspect of the present invention may further include a diffusion plate that is provided on the first main surface side and diffuses external light incident from the outside of the light guide.

  In the light guide in yet another aspect of the present invention, energy is transferred by 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 is obtained. You may inject from the said end surface.

  In the light guide in still another aspect of the present invention, among the plurality of optical functional materials, one or a plurality of optical functional materials other than the optical functional material having the largest peak wavelength of the emission spectrum has a fluorescence quantum yield. 80% or less of the optical functional material may be included.

  In the light guide in yet another aspect of the present invention, the fluorescence quantum yield of the optical functional material having the largest peak wavelength of the emission spectrum is the fluorescence quantum yield of any other optical functional material included in the light guide. It may be higher than the rate.

  In the light guide in still another aspect of the present invention, the optical functional material may include an optical functional material made of an inorganic material.

  In the light guide in one embodiment of the present invention, the optical functional material may include an optical functional material made of an organic-inorganic hybrid phosphor.

  In the light guide in still another aspect of the present invention, the optical functional material made of the inorganic material may include an optical functional material made of quantum dots.

  The light guide in still another aspect of the present invention may further include a reflective layer that reflects light propagating through the light guide.

  In the light guide body according to still another aspect of the present invention, the reflection layer may be a scattering reflection layer that scatters and reflects incident light.

  The light guide in still another aspect of the present invention may further include a retardation plate between the light guide and the reflective layer.

  In the light guide body according to still another aspect of the present invention, the retardation plate may be a 1 / 4λ plate.

  The light guide in still another aspect of the present invention may include a transparent light guide and the plurality of optical functional materials dispersed inside the transparent light guide.

 The light guide in still another aspect of the present invention is provided with a transparent light guide and a third main surface of the transparent light guide, and an optical functional material layer in which the plurality of optical functional materials are dispersed. And may be included.

  The light guide in still another aspect of the present invention may further include a peelable pressure-sensitive adhesive layer, and the transparent light guide and the optical functional material layer may be bonded by the pressure-sensitive adhesive layer.

  The solar cell module in the further another aspect of this invention is equipped with the said light guide and the solar cell element which light-receives the said light inject | emitted from the end surface of the said light guide.

  In the solar cell module according to still another aspect of the present invention, the spectral sensitivity of the solar cell element at the peak wavelength of the emission spectrum of the optical functional material having the largest emission spectrum peak wavelength among the plurality of optical functional materials is calculated as It may be larger than the spectral sensitivity of the solar cell element at the peak wavelength of the emission spectrum of any other optical functional material provided in the light body.

  The solar power generation device in the further another aspect of this invention is equipped with the said solar cell module.

  A solar cell module according to still another aspect of the present invention includes a first main surface, a second main surface, and a first end surface, includes an optical functional material, and includes one of external light incident from the first main surface. A first light guide that absorbs a portion by the optical functional material, propagates light emitted from the optical functional material, and exits from the first end surface; a third main surface; and a second end surface The light transmitted from the second main surface is incident on the third main surface, propagates, and is emitted from the second end surface, disposed on the second main surface side opposite to the first main surface. A second light guide body, a first solar cell element provided on the first end face for receiving light emitted from the first end face, and provided on the second end face and emitted from the second end face. A second solar cell element that receives the received light. The optical functional material includes an anisotropic optical functional material that emits light anisotropically. In the anisotropic light functional material, an angle formed by a direction in which the emission intensity of light emitted from the anisotropic light functional material is maximum and a normal line of the first main surface of the first light guide is equal to or greater than a critical angle. Is oriented.

In the solar cell module according to still another aspect of the present invention, in the first light guide, the propagating and emitting from the end surface means reflecting the first main surface and emitting from the end surface. Reflecting and exiting from the end face, reflecting from between the first main face and the second main face, and exiting from the end face, or entering neither the first main face nor the second main face Either from the end face,
The second light guide has a fourth main surface facing the third main surface,
In the second light guide, the propagating and emitting from the end surface means reflecting from the third main surface and emitting from the end surface, reflecting from the fourth main surface and emitting from the end surface, and the third main surface Either the light is emitted from the end surface while being reflected from the fourth main surface, or the light is emitted from the end surface without being incident on either the third main surface or the fourth main surface. .

  In the solar cell module according to still another aspect of the present invention, the anisotropic light functional material has the highest light emission intensity of light emitted from the anisotropic light functional material when viewed from the normal direction of the first main surface. The direction may be oriented so as to face the first end face.

  In the solar cell module according to still another aspect of the present invention, the anisotropic light functional material may include a light functional material made of a dichroic fluorescent dye.

  Moreover, in the solar cell module according to still another aspect of the present invention, the dichroic fluorescent dye includes a positive dichroic fluorescent dye in which the direction orthogonal to the molecular long axis is the direction with the highest emission intensity. May be.

  Moreover, in the solar cell module according to still another aspect of the present invention, the optical functional material includes a plurality of optical functional materials, and at least one of the optical functional materials includes the dichroic fluorescent dye. Good.

  In the solar cell module according to still another aspect of the present invention, the dichroic fluorescent dye may be an optical functional material having the largest peak wavelength of the emission spectrum among the plurality of optical functional materials.

  In the solar cell module according to still another aspect of the present invention, the optical functional material may include an optical functional material composed of the dichroic fluorescent dye and an isotropic optical functional material that absorbs light isotropically. Good.

  Further, in the solar cell module according to still another aspect of the present invention, the isotropic light functional material is a material having absorption isotropic property to absorb light isotropically, or an absorption anisotropic material to absorb light anisotropically. However, it may be an optical functional material that is not easily oriented with respect to the material included in the first light guide and is arranged in a random state.

  In the solar cell module according to still another aspect of the present invention, the optical functional material may include a plurality of optical functional materials made of the dichroic fluorescent dye.

  In the solar cell module according to still another aspect of the present invention, the first light guide causes energy transfer by the Forster mechanism between the plurality of optical functional materials, and has the largest peak wavelength of the emission spectrum. The light emitted from the optical functional material may be emitted from the first end face.

  The solar cell module according to still another aspect of the present invention may further include a diffusion plate that diffuses external light incident from the outside of the first light guide on the first main surface side.

  Moreover, in the solar cell module according to still another aspect of the present invention, the second light guide body reflects and propagates light between the third main surface and the inclined surface provided on the fourth main surface, The shape light guide body inject | emitted from the said 2nd end surface may be sufficient.

  The solar cell module according to still another aspect of the present invention may further include a reflective layer on the fourth main surface side, which reflects light transmitted from the fourth main surface side.

  Moreover, the solar cell module in the further another aspect of this invention WHEREIN: The said 1st solar cell element and the said 2nd solar cell element may be comprised by the common solar cell element.

  The solar power generation device in the further another aspect of this invention is equipped with the said solar cell module.

  According to one embodiment of the present invention, a light guide with high light extraction efficiency, a solar cell module with high power generation efficiency, and a solar power generation device using the same can be provided.

  According to another aspect of the present invention, since the second light guide is arranged behind the first light guide, the light having a deep incident angle is condensed by the first light guide and vertically Near-angle incident light can be condensed by the second light guide. Therefore, it is possible to provide a solar cell module with high light extraction efficiency and high power generation efficiency, and a solar power generation apparatus using the solar cell module.

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 characteristic of a dichroic fluorescent dye. It is a figure which shows the characteristic of a dichroic fluorescent dye. It is a figure which shows the orientation state of a dichroic fluorescent dye. It is a figure for demonstrating the effect | action of a dichroic fluorescent dye. It is a figure for demonstrating the effect | action of a dichroic fluorescent dye. It is a figure for demonstrating the effect | action of a dichroic fluorescent dye. It is a figure which shows the other example of the orientation state of a dichroic fluorescent dye. It is sectional drawing of the solar cell module of 2nd Embodiment. It is a figure which shows the emission spectrum of the 2nd optical functional material used with the solar cell module of 2nd Embodiment. It is a figure which shows the absorption spectrum of the 2nd optical functional material used with the solar cell module of 2nd Embodiment. It is a figure which shows the emission spectrum and absorption spectrum of a 1st optical functional material used with the solar cell module of 2nd Embodiment. 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 a photo-luminescence mechanism. It is explanatory drawing of a Forster mechanism. It is explanatory drawing of a Forster mechanism. It is explanatory drawing of 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 a figure which shows the spectral sensitivity curve of the various solar cell which can be utilized as a solar cell element. It is a figure which shows the energy conversion efficiency of the various solar cell shown in FIG. It is sectional drawing of the solar cell module of 4th Embodiment. It is a figure for demonstrating the effect | action of a diffusion plate. It is sectional drawing of the solar cell module of 5th Embodiment. It is sectional drawing of the solar cell module of 6th Embodiment. It is sectional drawing of the solar cell module of 8th Embodiment. It is sectional drawing of the solar cell module of 9th Embodiment. It is a figure which shows the emission spectrum of the optical functional material used with the solar cell module of 9th Embodiment, and the spectral sensitivity of a solar cell element. It is a figure which shows the emission spectrum of the optical functional material used with the solar cell module of 10th Embodiment, and the spectral sensitivity of a solar cell element. It is sectional drawing of the light guide applied to the solar cell module of 18th Embodiment. It is sectional drawing which shows the other structural example of the light guide of 18th Embodiment. It is sectional drawing which shows the structure of the principal part of a light guide. It is a schematic block diagram of a solar power generation device. It is a figure which shows the modification of an optical functional material. It is sectional drawing of the solar cell module of 7th Embodiment. It is sectional drawing of the solar cell module for demonstrating the effect | action of a 1/4 (lambda) board. It is sectional drawing of the solar cell module for demonstrating the effect | action of a 1/4 (lambda) board. It is sectional drawing of the solar cell module for demonstrating the effect | action of a 1/4 (lambda) board. It is sectional drawing of the solar cell module for demonstrating the effect | action of a 1/4 (lambda) board. It is sectional drawing of the solar cell module for demonstrating the effect | action of a 1/4 (lambda) board. It is a schematic perspective view of the solar cell module of 11th Embodiment. It is a sectional side view of the solar cell module of 11th Embodiment. It is a schematic diagram which shows schematic structure of a 2nd light guide. It is a schematic diagram which shows schematic structure of a 2nd light guide. It is a sectional side view which shows schematic structure of the solar cell module of 12th Embodiment. It is a sectional side view which shows schematic structure of the solar cell module of 13th Embodiment. It is a sectional side view which shows schematic structure of the solar cell module of 14th Embodiment. It is a figure for demonstrating the effect | action of an optical functional material. It is a sectional side view which shows schematic structure of the solar cell module of 15th Embodiment. It is a figure for demonstrating the effect | action of a diffusion plate. It is a sectional side view which shows schematic structure of the solar cell module of 16th Embodiment. It is a sectional side view which shows the modification of the solar cell module of 16th Embodiment. It is a sectional side view which shows schematic structure of the solar cell module of 17th Embodiment. It is sectional drawing of the light guide applied to the solar cell module of 19th Embodiment. It is sectional drawing which shows the other structural example of the light guide of 19th Embodiment.

[First Embodiment]
FIG. 1 is a schematic perspective view of the solar cell module 11 of the first embodiment.

  As shown in FIG. 1, the solar cell module 11 includes a light guide 14 (fluorescent light guide), a solar cell element 16, and a frame 110. The solar cell element 16 is a solar cell element 16 that receives light emitted from the end face 14 c of the light guide 14. The frame 110 is a frame 110 that integrally holds the light guide 14 and the solar cell element 16.

  The light guide 14 includes a first main surface 14a, a second main surface 14b, and an end surface 14c. The first main surface 14a is a first main surface 14a that is a light incident surface on which external light L is incident. The second main surface 14b faces the first main surface 14a. The end surface 14c of the second main surface 14b is an end surface 14c that is a light emission surface.

  In the present embodiment, the direction parallel to the first main surface 14a of the light guide 14 is the x-axis direction, the direction orthogonal to the x-axis direction is the y-axis direction, and the direction orthogonal to the first main surface 14a. (Thickness direction of the light guide 14) is defined as the z-axis direction.

  The light guide 14 is a substantially rectangular plate-like member having a first main surface 14a and a second main surface 14b. The first main surface 14a and the second main surface 14b of the light guide 14 are flat surfaces. In this embodiment, the light guide 14 is obtained by dispersing a plurality of optical functional materials in a base material (transparent substrate) made of a liquid crystalline polymer. At least one of the plurality of optical functional materials is a phosphor. The light emitted from the phosphor propagates through the light guide 14 and is emitted from the end face 14 c, and is used for power generation by the solar cell element 16.

The solar cell element 16 is disposed with the light receiving surface facing the four end surfaces 14 c of the light guide 14.
The solar cell element 16 is preferably optically bonded to the end face 14c. As the solar cell element 16, 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 16 because it can generate power with high efficiency. Examples of compound solar cells include InGaP, GaAs, InGaAs, AlGaAs, Cu (In, Ga) Se ₂ , Cu (In, Ga) (Se, S) ₂ , CuInS ₂ , CdTe, CdS, and the like. Examples of the quantum dot solar cell include Si and InGaAs.

  In FIG. 1, an example in which the solar cell element 16 is installed on the four end surfaces of the light guide 14 is shown, but the solar cell element 16 may be installed on a part of the four end surfaces of the light guide 14. Good. In the case where the solar cell element 16 is installed on a part of the end face (one side, two sides, or three sides) of the light guide body 14, the end face where the solar cell element is not installed is provided from the inside of the light guide body 14. It is preferable to install a reflective layer that reflects light traveling toward the outside of the light guide 14 toward the inside of the light guide 14.

The frame body 110 includes a transmission surface 110 a that transmits the light L on a surface facing the first main surface 14 a of the light guide body 14. The transmission surface 110a may be an opening of the frame 110, or may be a transparent member such as glass fitted into the opening of the frame 110. The first main surface 14a of the light guide 14 is a light incident surface.
A portion of the first main surface 14a that overlaps the transmission surface 110a of the frame 110 when viewed from the Z direction is a light incident region. The four end faces 14 c of the light guide body 14 are the light exit faces of the light guide body 14.

  FIG. 2 is a cross-sectional view of the solar cell module 11.

  The light guide 14 includes a plurality of optical functional materials. The plurality of optical functional materials include a first optical functional material 12 and a second optical functional material 18.

The second optical functional material 18 is a material having a property of absorbing light isotropically (absorption isotropic property).
Alternatively, the optical functional material has a property of absorbing light anisotropically (absorption anisotropy) but is difficult to be oriented with respect to the light guide forming material and is in a random state.

  The first optical functional material 12 is a material having a property of emitting light anisotropically (emission anisotropy).

  In the case of the present embodiment, in the light guide 14, as the optical functional material, a second optical functional material 18 that absorbs light isotropically, and a first optical functional material 12 that emits light anisotropically, It is included.

  As the second optical functional material 18, a phosphor having a predetermined absorption wavelength region is used. The phosphor 18 absorbs external light and emits fluorescence. For example, the phosphor 18 is mixed when the light guide 14 is molded.

  As the first optical functional material 12, an optical functional material made of a dichroic fluorescent dye is used. The “dichroic fluorescent dye” is a dye having a property of absorbing light anisotropically (absorption anisotropy) and a property of emitting light anisotropically (light emission anisotropy). In the present embodiment, a positive dichroic fluorescent dye having a direction with the highest emission intensity is used as the first optical functional material made of the dichroic fluorescent dye.

  The dichroic fluorescent dye is not limited to the positive dichroic fluorescent dye, and various dichroic fluorescent dyes can be used. For example, a negative dichroic fluorescent dye in which the direction of the molecular major axis is the direction in which the emission intensity is the highest can be used.

  3A and 3B are diagrams showing the characteristics of the dichroic fluorescent dye. FIG. 3A is a diagram showing the absorption characteristics of a dichroic fluorescent dye. FIG. 3B is a diagram showing the light emission characteristics of the dichroic fluorescent dye. 3A and 3B, the symbol V1 is the molecular long axis of the dichroic fluorescent dye 12, and the symbol V2 is an axis orthogonal to the molecular long axis V1.

As shown in FIG. 3A, the dichroic fluorescent dye 12 of this embodiment has absorption anisotropy. For example, when the absorption characteristics of light incident on the dichroic fluorescent dye 12 from below in the direction along the molecular long axis V1 are viewed, before entering the dichroic fluorescent dye 12 and via the dichroic fluorescent dye 12 The height of the curve showing the absorption characteristics hardly changes after and after. The dichroic fluorescent dye 12 hardly absorbs light incident in the direction along the molecular long axis V1 from below.
On the other hand, when the absorption characteristics of light incident on the dichroic fluorescent dye 12 from the left side in the direction along the axis V2 orthogonal to the molecular long axis are seen, the dichroic fluorescence before entering the dichroic fluorescent dye 12 After passing through the dye 12, the height of the curve showing the absorption characteristics is smaller after passing through the dichroic fluorescent dye 12. The dichroic fluorescent dye 12 absorbs most of the light incident in the direction along the axis V2 orthogonal to the molecular long axis from the left side. As described above, the dichroic fluorescent dye 12 of the present embodiment has relatively small absorption characteristics in the direction along the molecular long axis V1, and relatively absorbs in the direction along the axis V2 orthogonal to the molecular long axis. Great characteristics.

  As shown in FIG. 3B, the dichroic fluorescent dye 12 of the present embodiment has emission anisotropy. The direction along the molecular long axis V1 is the direction with the smallest emission intensity. On the other hand, the direction along the axis V2 orthogonal to the molecular long axis is the direction with the highest emission intensity. As described above, the dichroic fluorescent dye 12 of the present embodiment has a relatively small emission intensity in the direction along the molecular long axis V1, and relatively emits light in the direction along the axis V2 orthogonal to the molecular long axis. High strength.

  FIG. 4 is a diagram showing the orientation state of the dichroic fluorescent dye. In FIG. 4, the symbol V1 is the molecular long axis of the dichroic fluorescent dye 12, and the symbol V2 is an axis orthogonal to the molecular long axis V1.

  As shown in FIG. 4, the dichroic fluorescent dye 12 of this embodiment is oriented so that the axis V2 orthogonal to the molecular long axis and the first main surface 14a of the light guide 14 are parallel to each other. That is, the dichroic fluorescent dye 12 of this embodiment is oriented so that the direction in which the emission intensity of the light emitted from the dichroic fluorescent dye 12 is the largest is parallel to the first main surface 14a of the light guide 14. Has been.

  The light guide 14 of the present embodiment is a substantially rectangular plate-like member having a first main surface 14a and a second main surface 14b perpendicular to the Z axis (parallel to the XY plane). Therefore, the dichroic fluorescent dye 12 of this embodiment is oriented so that the axis V2 orthogonal to the molecular long axis and the second main surface 14b of the light guide 14 are parallel to each other. That is, the dichroic fluorescent dye 12 of this embodiment is oriented so that the direction in which the emission intensity of the light emitted from the dichroic fluorescent dye 12 is the largest is parallel to the second main surface 14b of the light guide 14. Has been.

Here, a method for orienting the dichroic fluorescent dye 12 will be described with an example.
In order to align the dichroic fluorescent dye 12, a liquid crystal polymer or the like is used as a light guide forming material. For example, a liquid crystal polymer (UCL018) manufactured by DIC is used.
First, UCL018 (polymer liquid crystal manufactured by DIC), Coumarin 6 (dichroic fluorescent dye), FC-4430 (surfactant), and toluene are mixed. The mixing ratio of each material is UCL018 (40%), Coumarin 6 (0.40%), FC-4430 (0.40%), and toluene (59.2%).
Next, the produced mixed solution is applied onto the substrate using a spin cast manufacturing method. The coating conditions are 20 sec and film formation at 500 rpm to form a film having a thickness of 1 μm. However, the film forming conditions are not limited to this, and the rotation time and the rotation speed are appropriately changed, and the film thickness is also changed in accordance with the light absorption amount of the fluorescent dye. Although details of an example of the spin cast manufacturing method are described here, the manufacturing method is not limited to this, and a manufacturing method such as slit coating, dip coating, roll coating, or bar coating may be used.
Next, the substrate on which the mixed solution is applied is placed on a hot plate and heat-treated under the conditions of a processing temperature of 50 ° C. and a processing time of 1 min to evaporate the solvent in the mixed solution.
Next, the processing temperature is lowered to room temperature.
Next, i-line (365 nm) is irradiated using a UV lamp, and exposure is performed for a processing time of 2 min.
Through the above steps, the dichroic fluorescent dye 12 can be oriented.

Here, an example is given and demonstrated about the method for verifying the orientation state of the dichroic fluorescent dye 12. FIG.
First, light of a predetermined wavelength band is incident on the light guide body 14 including the dichroic fluorescent dye 12 from each direction, and it is verified whether or not there is a place where the amount of light absorption differs depending on the light incident direction. If there is a difference in the amount of light absorption, the wavelength of the light is examined. The wavelength of this light becomes the absorption wavelength of the dichroic fluorescent dye 12.
Next, light corresponding to the absorption wavelength of the dichroic fluorescent dye 12 is incident on the light guide body 14, and confinement efficiency (light absorption efficiency of the dichroic fluorescent dye 12) is isotropically emitted. It is confirmed that the value is higher than that assumed. (When isotropic light is emitted, the confinement efficiency is 75% when the refractive index of the light guide is 1.5.)
Next, light having a wavelength other than the absorption wavelength of the dichroic fluorescent dye 12 is incident on the light guide 14, and the light emitted from the end face of the light guide 14 is the emission wavelength of the dichroic fluorescent dye 12. Make sure that there is.
With the above flow, the orientation state of the dichroic fluorescent dye 12 can be verified.

  5A to 5C are diagrams for explaining the action of the dichroic fluorescent dye. FIG. 5A is a diagram illustrating how energy transfer occurs between the phosphor 18 (second optical functional material) and the dichroic fluorescent dye 12 (first optical functional material). FIG. 5B and FIG. 5C are diagrams showing how the light emitted from the dichroic fluorescent dye 12 propagates inside the light guide 14. In FIG. 5C, the symbol θ is an angle formed by the traveling direction of a part of the light L1 emitted from the dichroic fluorescent dye 12 and the normal line of the second main surface 14b of the light guide 14, and the symbol θm is Is the critical angle.

  As shown in FIG. 5A, a part of the external light incident on the first main surface 14 a of the light guide 14 is absorbed by the phosphor 18. When the phosphor 18 absorbs part of the external light, the excitation energy moves from the phosphor 18 toward the dichroic fluorescent dye 12.

  As shown in FIG. 5B, the dichroic fluorescent dye 12 emits light anisotropically by excitation energy from the phosphor 18. The dichroic fluorescent dye 12 of this embodiment is oriented so that the direction in which the emission intensity of the light emitted from the dichroic fluorescent dye 12 is the largest is parallel to the first main surface 14a of the light guide 14. Yes. Therefore, light having the highest emission intensity among the light emitted from the dichroic fluorescent dye 12 is directly guided to the solar cell element 16. The mechanism by which the dichroic fluorescent dye 12 emits light anisotropically by excitation energy from the phosphor 18 will be described later.

  As shown in FIG. 5C, most of the light emitted from the dichroic fluorescent dye 12 has a large incident angle θ on the first main surface 14 a or the second main surface 14 b of the light guide 14.

  Here, for example, when the refractive index of the liquid crystalline polymer constituting the light guide 14 is 1.5 and the refractive index of air is 1.0, the critical angle θm in the second main surface 14b of the light guide 14, that is, the guide The critical angle at the interface between the liquid crystalline polymer constituting the light body 14 and air is about 42 ° from Snell's law. When a part of the light L1 emitted from the dichroic fluorescent dye 12 is incident on the second main surface 14b, the incident angle of the light L1 on the second main surface 14b is larger than 42 ° which is a critical angle. Since the total reflection condition is satisfied, the light L is totally reflected by the second main surface 14b. Thereafter, the light L is repeatedly reflected between the first main surface 14 a and the second main surface 14 b and guided to the solar cell element 16.

  In the dichroic fluorescent dye 12 of the present embodiment, the direction in which the light emission intensity of the light emitted from the dichroic fluorescent dye 12 is the smallest is orthogonal to the first main surface 14a of the light guide 14. When light L2 from the direction along the molecular long axis of light emitted from the dichroic fluorescent dye 12 is incident on the second main surface 14b, the incident angle of the light L2 on the second main surface 14b is a critical angle 42. Since it becomes smaller than ° and does not satisfy the total reflection condition, the light L2 is emitted to the external space.

  That is, the light emitted from the dichroic fluorescent dye 12 is confined inside the light guide 14 when the angle of incidence on the first main surface 14a or the second main surface 14b is larger than the critical angle, and the first main surface When the incident angle to 14a or the second main surface 14b is smaller than the critical angle, the light is emitted to the outside. In the present embodiment, the dichroic fluorescent dye 12 is oriented so that the direction in which the emission intensity of the light emitted from the dichroic fluorescent dye 12 is the largest is parallel to the first main surface 14 a of the light guide 14. ing. Therefore, most of the light emitted from the dichroic fluorescent dye 12 has a large incident angle θ on the first main surface 14a or the second main surface 14b of the light guide 14 and satisfies the total reflection condition. It will be. Therefore, most of the light emitted from the dichroic fluorescent dye 12 is confined inside the light guide 14 and guided to the solar cell element 16 without being emitted outside.

  As described above, in the solar cell module 11 of the present embodiment, the dichroic fluorescent dye 12 is included in the light guide 14, and the light emission intensity of the light emitted from the dichroic fluorescent dye 12 is increased. It is oriented so that the largest direction faces the end surface of the light guide 14 on which the solar cell element 16 is disposed. In the present embodiment, the direction in which the emission intensity is the largest among the light emitted from the dichroic fluorescent dye 12 is parallel to the first main surface 14a of the light guide 14, so that the sunlight incident on the light guide 14 is Most of them are directly led to the solar cell element 16. Thereby, it is suppressed that most of the sunlight incident on the light guide body 14 is transmitted through the light guide body 14 before reaching the solar cell element 16. Therefore, most of the sunlight incident on the light guide 14 can be contributed to power generation. Therefore, a solar cell module with high power generation efficiency can be provided.

  In the present embodiment, the configuration in which the axis V2 orthogonal to the molecular long axis and the first main surface 14a of the light guide 14 are aligned in parallel has been described as an example. Not exclusively.

  FIG. 6 is a diagram showing another example of the orientation state of the dichroic fluorescent dye. In FIG. 6, symbol V1 is a molecular long axis of the dichroic fluorescent dye 12, and symbol V2 is an axis orthogonal to the molecular long axis V1.

  For example, in the dichroic fluorescent dye 12 of the present embodiment, as shown in FIG. 6, the angle θ formed by the axis V2 orthogonal to the molecular long axis and the normal line of the second main surface 14b of the light guide 14 is critical. It may be oriented so that it has an angle θm or more. In other words, the dichroic fluorescent dye 12 of the present embodiment has an angle θ formed by the direction in which the emission intensity of the light emitted from the dichroic fluorescent dye 12 is highest and the normal line of the second main surface 14b of the light guide 14. May be oriented so as to be not less than the critical angle θm.

  In addition, the light guide 14 of this embodiment is a substantially rectangular plate-shaped member having a first main surface 14a and a second main surface 14b. Therefore, in the dichroic fluorescent dye 12 of the present embodiment, the angle θ formed by the axis V2 orthogonal to the molecular long axis and the normal line of the first main surface 14a of the light guide 14 is not less than the critical angle θm. It may be oriented. That is, the dichroic fluorescent dye 12 of the present embodiment has an angle θ formed by the direction in which the light emission intensity of the light emitted from the dichroic fluorescent dye 12 is highest and the normal line of the first main surface 14a of the light guide 14. May be oriented so as to be not less than the critical angle θm.

  Even in such an orientation state, most of the sunlight incident on the light guide 14 is suppressed from passing through the light guide 14 before reaching the solar cell element 16. Therefore, most of the sunlight incident on the light guide 14 can be contributed to power generation.

  For example, when the solar cell module 11 is installed on a roof or the like and arranged with the first main surface 14a facing upward, the axis V2 orthogonal to the molecular long axis and the first main surface 14a of the light guide 14 are parallel to each other. It becomes possible to set it as the structure which absorbs sunlight compared with the structure orientated so that it may become. That is, as shown in FIG. 39, the elevation angle θs of the sun S varies from about 30 ° to about 80 ° depending on the season in Japan, but the axis V2 shown in FIG. By arranging so as to face the sun, it is possible to easily absorb sunlight.

  Moreover, in this embodiment, although the solar cell module 11 provided with the light guide 14 and the solar cell element 16 was mentioned and demonstrated, it is not restricted to this. For example, the present embodiment can be applied to a configuration that does not include the solar cell element 16, that is, a configuration that includes only the light guide 14. According to this configuration, it is possible to provide the light guide 14 having high light extraction efficiency from the end face.

[Second Embodiment]
FIG. 7 is a cross-sectional view of the solar cell module 11A of the second embodiment.
The basic configuration of the solar cell module 11A of the present embodiment is the same as that of the first embodiment, and two types of phosphors (first phosphor 18a and second phosphor 18b) are provided inside the light guide body 14. This is different from the first embodiment. In FIG. 7, about the structure which is common in the solar cell module 11 of 1st Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

In the solar cell module 11 </ b> A of the present embodiment, a plurality of types of phosphors having different absorption wavelength ranges (for example, the first phosphor 18 a and the second phosphor 18 b in FIG. 7) are used as the second optical functional material 18.
As the first phosphor 18a, for example, Lumogen F Violet 570 (trade name) manufactured by BASF can be used.
As the second phosphor 18b, for example, Lumogen F Yellow 083 (trade name) manufactured by BASF can be used.

FIG. 8 is a diagram showing an emission spectrum of the second optical functional material (first phosphor 18a, second phosphor 18b) used in the solar cell module 11A of the second embodiment.
FIG. 9 is a diagram showing an absorption spectrum of the second optical functional material (first phosphor 18a, second phosphor 18b) used in the solar cell module 11A of the second embodiment.

As shown in FIG. 8, the emission spectrum 1101 of the first phosphor 18a has a peak wavelength at 430 nm, and the emission spectrum 1102 of the second phosphor 18b has a peak wavelength at 500 nm.
As shown in FIG. 9, the absorption spectrum 1111 of the first phosphor 18a has a peak wavelength at 380 nm, and the absorption spectrum 1112 of the second phosphor 18b has a peak wavelength at 480 nm.

The dichroic fluorescent dye 12 of the present embodiment emits light anisotropically by energy transfer from the first phosphor 18a and the second phosphor 18b.
As the dichroic fluorescent dye 12, for example, a material represented by the following chemical formula (1) can be used.

Hereinafter, the production | generation method of the material shown to Chemical formula (1) is demonstrated.
First, a material represented by the following chemical formula (2) is prepared.

Next, the material represented by the chemical formula (2) is
It is chemically reacted with 5-fromylthiophene-2-ylboronic acid, Pd (PPh ₃ ) ₂ Cl ₂ , 2 M Na ₂ CO ₃ , benzene / EtOH. Thereby, the material shown in the following chemical formula (3) is generated.

Next, the material represented by the chemical formula (3) is
Chemical reaction with arylmethyltriphenylphosphonium bromide, KOH, DMSO. Thereby, the dichroic fluorescent dye 12 shown to Chemical formula (1) in this embodiment can be produced | generated.

FIG. 10 is a diagram showing an emission spectrum and an absorption spectrum of the first optical functional material (dichroic fluorescent dye 12) used in the solar cell module 11A of the second embodiment. In FIG. 10, the symbol F _// is a light emission characteristic in a direction parallel to the molecular long axis of the dichroic fluorescent dye 12. The symbol F _⊥ is a light emission characteristic in a direction orthogonal to the molecular long axis of the dichroic fluorescent dye 12. Symbol _{N F} is the ratio of F _// and _{F ⊥ (F // / F ⊥} ). The symbol A _// is an absorption characteristic in a direction parallel to the molecular long axis of the dichroic fluorescent dye 12. The symbol A _吸収 is an absorption characteristic in a direction orthogonal to the molecular long axis of the dichroic fluorescent dye 12. Symbol _{N A} is the ratio of A _// and _{A ⊥ (A // / A ⊥} ).

As shown in FIG. 10, the emission spectrum of the dichroic fluorescent dye 12 has a peak wavelength at 640 nm in a direction parallel to the molecular long axis (F _// ). Moreover, it has a peak wavelength at 630 nm in the direction orthogonal to the molecular long axis (F _⊥ ).
On the other hand, the absorption spectrum of the dichroic fluorescent dye 12 has a peak wavelength at 530 nm (A _// ) in the direction parallel to the molecular long axis. Moreover, it has a peak wavelength at 520 nm (A _⊥ ) in the direction orthogonal to the molecular long axis.

Also in the solar cell module 11A of the present embodiment, most of the sunlight incident on the light guide 14 can be contributed to power generation.
Further, in the present embodiment, a plurality of types (two types) of second optical functional materials (first phosphor 18 a and second phosphor 18 b) are included in the light guide 14. Thereby, the sunlight which injected into the light guide 14 can be utilized for electric power generation in a wide wavelength range.
Therefore, a solar cell module with high power generation efficiency can be provided.

[Third Embodiment]
FIG. 11 is a cross-sectional view of the solar cell module 11B of the third embodiment.
The basic configuration of the solar cell module 11B of this embodiment is the same as that of the first embodiment, and there are three types of phosphors (first phosphor 18a, second phosphor 18b, and third phosphor) inside the light guide body 14. 18c) is different from the first embodiment. In FIG. 11, about the structure which is common in the solar cell module 11 of 1st Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  As the second optical functional material 18, a plurality of types of phosphors having different absorption wavelength ranges (for example, the first phosphor 18a, the second phosphor 18b, and the third phosphor 18c in FIG. 11) are dispersed. The first phosphor 18a absorbs ultraviolet light and emits blue fluorescence. The second phosphor 18b absorbs blue light and emits green fluorescence. The third phosphor 18c absorbs green light and emits red fluorescence. For example, the first phosphor 18a, the second phosphor 18b, and the third phosphor 18c are mixed when the light guide is molded. The mixing ratio of the first phosphor 18a, the second phosphor 18b, and the third phosphor 18c is as follows. The mixing ratio of the first phosphor 18a, the second phosphor 18b, and the third phosphor 18c is shown as a volume ratio with respect to the light guide.

First phosphor 18a: BASF Lumogen F Violet 570 (trade name) 0.02%, second phosphor 18b: BASF Lumogen F Yellow 083 (trade name) 0.02%, third phosphor 18c: BASF Lumogen F Red 305 (trade name) 0.02%.

The dichroic fluorescent dye 12 of this embodiment emits light anisotropically by energy transfer from the first phosphor 18a, the second phosphor 18b, and the third phosphor 18c.
Hereinafter, a mechanism in which the dichroic fluorescent dye 12 emits light anisotropically by excitation energy from the phosphors 18a, 18b, and 18c will be described.

12 to 15 are diagrams showing the emission characteristics and absorption characteristics of the first phosphor 18a, the second phosphor 18b, and the third phosphor 18c.
In FIG. 12, a curve 1121 shows the spectrum of sunlight after the ultraviolet light is absorbed by the first phosphor 18a. A curve 1122 shows the spectrum of sunlight after the blue light is absorbed by the second phosphor 18b. A curve 1123 indicates the spectrum of sunlight after the green light is absorbed by the third phosphor 18c. A curve 1124 shows the spectrum of sunlight.
In FIG. 13, a curve 1125 shows the spectrum of sunlight after ultraviolet light, blue light, and green light are absorbed by the first phosphor 18a, the second phosphor 18b, and the third phosphor 18c. A curve 1124 shows the spectrum of sunlight.
In FIG. 14, a curve 1126 is an emission spectrum of the first phosphor 18a. A curve 1127 is an emission spectrum of the second phosphor 18b. A curve 1128 is an emission spectrum of the third phosphor 18c.
In FIG. 15, a curve 1129 is a spectrum of light emitted from the end face of the light guide including the first phosphor 18a, the second phosphor 18b, and the third phosphor 18c.

  As shown in FIGS. 12 and 13, the first phosphor 18a absorbs light having a wavelength of approximately 420 nm or less. The second phosphor 18b absorbs light having a wavelength of approximately 420 nm or more and 520 nm or less. The third phosphor 18c absorbs light having a wavelength of approximately 520 nm or more and 620 nm or less. The first phosphor 18a, the second phosphor 18b, and the third phosphor 18c 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 48%. Therefore, 48% of the light incident on the light incident surface of the light guide is absorbed by the first phosphor 18a, the second phosphor 18b, and the third phosphor 18c included in the light guide.

As shown in FIG. 14, the emission spectrum of the first phosphor 18a has a peak wavelength at 430 nm. The emission spectrum of the second phosphor 18b has a peak wavelength at 520 nm. The emission spectrum of the third phosphor 18c has a peak wavelength at 630 nm.
However, as shown in FIG. 15, the spectrum of light emitted from the end face of the light guide including the first phosphor 18a, the second phosphor 18b, and the third phosphor 18c is the emission spectrum of the third phosphor 18c. The peak wavelength has only a wavelength corresponding to the peak wavelength (630 nm) of the first phosphor 18a, and corresponds to the peak wavelength (430 nm) of the emission spectrum of the first phosphor 18a and the peak wavelength (520 nm) of the emission spectrum of the second phosphor 18b. The wavelength does not have a peak wavelength.
Accordingly, excitation energy is transferred between the three types of phosphors used here by the Forster mechanism, and fluorescence emitted from the third phosphor having the largest peak wavelength of the fluorescence spectrum is obtained.

  The cause of the disappearance of the peak of the emission spectrum corresponding to the first phosphor 18a and the peak of the emission spectrum corresponding to the second phosphor 18b is the energy transfer between the phosphors due to 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.

  The dichroic fluorescent dye 12 of this embodiment emits light anisotropically by energy transfer from the first phosphor 18a, the second phosphor 18b, and the third phosphor 18c. In the present embodiment, the energy transfer from the first phosphor 18a, the second phosphor 18b, and the third phosphor 18c to the dichroic fluorescent dye 12 includes energy transfer by photoluminescence, energy transfer by Forster mechanism. Either can be adopted.

  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 18a, the second phosphor 18b, and the third phosphor 18c is increased, and the Forster mechanism is used between the phosphors. Energy transfer is performed.

  Here, the Forster mechanism will be described with reference to FIGS. 16A to 17B. FIG. 16A is a diagram illustrating energy transfer by photoluminescence (color conversion by photoluminescence). FIG. 16B is a diagram illustrating energy transfer (color conversion by energy transfer) by the Forster mechanism. FIG. 17A is a diagram for explaining a generation mechanism of energy transfer by the Forster mechanism. FIG. 17B is a diagram showing energy transfer by the Forster mechanism.

As shown in FIG. 16B, in an organic molecule, inorganic nanoparticle, or organic-inorganic hybrid phosphor, energy transfer may occur from a molecule A in an excited state to a molecule B in a ground state by a 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 a host molecule and the molecule B is a guest molecule, the rate constant k _{H → G} (movement probability) when energy is transferred is as shown in Equation (1).

In equation (1), 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.

  The above [1] represents the ease of resonance between two adjacent phosphors. For example, as shown in FIG. 17A, 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. 17B, when the guest molecule B in the ground state exists near the host molecule A in the excited state, the wave function of the guest molecule A changes due to the resonance property, 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. 13 and 15 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 different sized quantum dots in a 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 1 ′, 3′-dihydro-1 ′, 3 ′, 3′-trimethyl-6-nitrospiro [ 2H-1-benzopyran-'2,2 '-(2H] -indole] is well matched with the light absorption spectrum of a ring-opened Spiropyran molecule (SPO open; Merocynanine form) obtained by irradiating ultraviolet rays to quantum dots. In general, inorganic phosphors have an excellent light resistance compared to organic phosphors, and are therefore advantageous when used for a long period of time.

  Normally, when two kinds of phosphors are mixed, as shown in FIG. 16A, the phosphor A first emits light with a certain efficiency, enters the phosphor B, and the phosphor B absorbs and emits light. 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. 16B, 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 light-emitting material such as a phosphor but also in a non-light-emitting body 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. 18 shows a spectral sensitivity curve 1134 of an amorphous silicon solar cell which is an example of the solar cell element 16 together with an emission spectrum 1131 of the first phosphor, an emission spectrum 1132 of the second phosphor, and an emission spectrum 1133 of the third phosphor. FIG.

  The spectrum of the light L1 emitted from the end face 14c of the light guide body 14 substantially matches the emission spectrum 1133 of the third phosphor 18c. Therefore, the solar cell element 16 should just have a high sensitivity in the peak wavelength (630 nm) of the emission spectrum 1133 of the 3rd fluorescent substance 18c. As shown in FIG. 18, the amorphous silicon solar cell has the highest spectral sensitivity with respect to light having a wavelength near 600 nm. When the spectral sensitivity 1134 of the amorphous silicon solar cell at the peak wavelength of the emission spectrum 1131 of the first phosphor, the peak wavelength of the emission spectrum 1132 of the second phosphor, and the peak wavelength of the emission spectrum 1133 of the third phosphor is compared, the light emission is highest. The spectral sensitivity of the amorphous silicon solar cell at the peak wavelength of the emission spectrum of the third phosphor having a large spectrum peak wavelength is any other phosphor (first phosphor or second phosphor) provided in the light guide. It is larger than the spectral sensitivity of the amorphous silicon solar cell at the peak wavelength of the emission spectrum. Therefore, if an amorphous silicon solar cell is used as the solar cell element 16, power generation can be performed with high efficiency.

  The type of solar cell applied to the solar cell element 16 is determined according to the wavelength of light incident on the solar cell element. In FIG. 18, an amorphous silicon solar cell is used as the solar cell element 16, but the solar cell element 16 is not limited to this.

FIG. 19 is a diagram showing spectral sensitivity curves of various solar cells that can be used as the solar cell element 16. FIG. 20 is a diagram showing the energy conversion efficiency η _λ of these solar cells. In FIG. 19, reference numeral 1141 indicates a spectral sensitivity curve of the single crystal silicon solar cell. Reference numeral 1142 indicates a spectral sensitivity curve of the amorphous silicon solar cell (single junction). Reference numeral 1143 indicates a spectral sensitivity curve of the gallium arsenide solar cell (single junction). Reference numeral 1144 denotes a spectral sensitivity curve of the cadmium tellurium solar cell. Reference numeral 1145 indicates a spectral sensitivity curve of the Cu (In, Ga) (Se, S) ₂ solar cell. In FIG. 20, reference numeral 1151 indicates the energy conversion efficiency η _λ of the single crystal silicon solar cell. Reference numeral 1152 indicates the energy conversion efficiency η _λ of the amorphous silicon solar cell (single junction). Reference numeral 1153 indicates the energy conversion efficiency η _λ of the gallium arsenide solar cell (single junction). Reference numeral 1154 indicates the energy conversion efficiency η _λ of the cadmium tellurium solar cell. Reference numeral 1155 indicates the energy conversion efficiency η _λ of the Cu (In, Ga) (Se, S) ₂ solar cell.

  In the solar cells shown in FIGS. 19 and 20, the spectral sensitivity and energy conversion efficiency of the solar cell at the peak wavelength (630 nm) of the emission spectrum of the third phosphor 18c having the largest emission spectrum peak wavelength are as follows. Is larger than the spectral sensitivity and energy conversion efficiency of the solar cell at the peak wavelength of the emission spectrum of any of the other phosphors (first phosphor 18a, second phosphor 18b). Therefore, if these solar cells are used as the solar cell element 16, power generation can be performed with high efficiency.

  19 and 20 are examples of solar cells that can be used as the solar cell element 16, and other solar cells can be used as a matter of course. The solar cell element 16 cannot have high spectral sensitivity with respect to the entire wavelength region of sunlight, such as a dye-sensitized solar cell or an organic solar cell, but with respect to light in a specific narrow wavelength region. It is also possible to actively use solar cells having very high spectral sensitivity.

Also in the solar cell module 11B of this embodiment, most of the sunlight incident on the light guide 14 can be contributed to power generation.
Further, in the present embodiment, a plurality of types (three types) of second optical functional materials (first phosphor 18a, second phosphor 18b, and third phosphor 18c) are included in the light guide body 14. ing. Thereby, the sunlight which injected into the light guide 14 can be utilized for electric power generation in a wide wavelength range.
Therefore, a solar cell module with high power generation efficiency can be provided.

  In the solar cell module 11B of the present embodiment, a part of the external light L incident on the first main surface 14a is converted into a plurality of optical functional materials (first phosphor 18a, second phosphor 18b, and third phosphor 18c. ) To cause energy transfer by a Forster mechanism among a plurality of optical functional materials, and light emitted from the optical functional material (third phosphor 18c) having the largest peak wavelength of the emission spectrum is dichroic. The directivity is enhanced by the fluorescent dye 12, the light is condensed on the end surface 14 c of the light guide 14, and is incident on the solar cell element 16. Therefore, as the solar cell element 16, a solar cell having very high spectral sensitivity in a limited narrow wavelength range can be used.

  In the present embodiment, the light guide body 14 includes three types of second optical functional materials (first phosphor 18a, second phosphor 18b, and third phosphor 18c). Although it gave an example, it is not restricted to this. For example, the present embodiment can also be applied to a configuration in which four or more types of second optical functional materials are included in the light guide 14.

[Fourth Embodiment]
FIG. 21 is a cross-sectional view of the solar cell module 11C of the fourth embodiment. The basic configuration of the solar cell module 11C of the present embodiment is the same as that of the third embodiment, and is different from the first embodiment in that a diffusion plate 13 is provided on the first main surface 14a side of the light guide 14. In FIG. 21, the same reference numerals are given to the configurations common to the solar cell module 11 </ b> B of the third embodiment, and detailed description thereof is omitted.

  As shown in FIG. 21, in the solar cell module 11C of the present embodiment, the diffusion plate 13 is provided on the first main surface 14a side of the light guide 14 via an air layer. The presence of an air layer between the light guide 14 and the diffusion plate 13 makes it easy for light emitted from the dichroic fluorescent dye 12 to satisfy the total reflection condition at the interface between the light guide 14 and the air layer.

  In the present embodiment, the diffusion plate 13 is provided on the first main surface 14a side of the light guide 14 via the air layer, but the present invention is not limited to this. For example, the diffusion plate 13 may be provided in direct contact with the first main surface 14a of the light guide body 14 without using an air layer.

  The diffusing plate 13 is configured by dispersing a large number of light scattering bodies such as acrylic beads in a binder resin such as an acrylic resin. As an example, the thickness of the diffusion plate 13 is about 20 μm, and the spherical diameter of the spherical light scatterer is about 0.5 μm to 20 μm. The diffuser plate 13 diffuses external light isotropically from the outside of the light guide 14 toward the inside of the light guide 14.

  The light scatterer is not limited to this, and is made of an acrylic polymer, an olefin polymer, a vinyl polymer, a cellulose polymer, an amide polymer, a fluorine polymer, a urethane polymer, a silicone polymer, an imide polymer, or the like. You may be comprised with appropriate transparent substances, such as a resin piece and a glass bead. In addition to these transparent substances, scatterers and reflectors that do not absorb light can be used. The shape of each light scatterer can be formed in various shapes such as a spherical shape, an elliptical spherical shape, a flat plate shape, and a polygonal cube. It is only necessary that the size of the light scatterer is uniform or nonuniform.

FIG. 22 is a diagram for explaining the operation of the diffusion plate. In FIG. 22, the phosphor is not shown for convenience.
In the case of the present embodiment, as shown in FIG. 22, the diffusion plate 13 is disposed on the first main surface 14 a side of the light guide 14. As a result, the light incident perpendicularly to the solar cell module 11 </ b> C (the diffusion plate 13) is diffused by the diffusion plate 13 and then enters the light guide body 14. For this reason, light of various angles enters the dichroic fluorescent dye 12. In other words, the proportion of light in the direction in which the dichroic fluorescent dye 12 is easy to absorb is larger than when there is no diffuser. Therefore, the dichroic fluorescent dye 12 having an absorption characteristic that is relatively small in the direction along the molecular long axis V1 and relatively large in the direction along the axis V2 orthogonal to the molecular long axis. Even if it exists, it becomes possible to absorb a part of light which enters perpendicularly with respect to solar cell module 11A (diffusion plate 13).

  In the solar cell module 11C of the present embodiment, since the diffusion plate 13 is provided, a part of the external light incident on the first main surface 14a of the light guide 14 is two compared to the configuration of the third embodiment. The proportion absorbed by the chromatic fluorescent dye 12 increases. When the dichroic fluorescent dye 12 absorbs part of external light, it emits light anisotropically. Also in the dichroic fluorescent dye 12 of the present embodiment, the direction in which the emission intensity of the light emitted from the dichroic fluorescent dye 12 is the largest is oriented so as to be parallel to the first main surface 14a of the light guide 14. Therefore, light having the highest emission intensity among the light emitted from the dichroic fluorescent dye 12 is directly guided to the solar cell element 16. Therefore, most of the sunlight incident on the light guide 14 can be contributed to power generation.

[Fifth Embodiment]
FIG. 23 is a cross-sectional view of the solar cell module 11D of the fifth embodiment. The basic configuration of the solar cell module 11D of the present embodiment is the same as that of the fourth embodiment, and is different from the fourth embodiment in that the reflective layer 15 is provided on the second main surface 14b side of the light guide 14. In FIG. 23, about the structure which is common in the solar cell module 11C of 4th Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  As shown in FIG. 23, in the solar cell module 11D of the present embodiment, the reflective layer 15 is provided on the second main surface 14b side of the light guide 14 via an air layer. The presence of an air layer between the light guide 14 and the reflective layer 15 makes it easier for light emitted from the dichroic fluorescent dye 12 to satisfy the total reflection condition at the interface between the light guide 14 and the air layer.

  In the present embodiment, the reflective layer 15 is provided on the second main surface 14b side of the light guide 14 via the air layer, but the present invention is not limited to this. For example, the reflective layer 15 may be provided in direct contact with the second main surface 14b of the light guide 14 without an air layer.

  The reflective layer 15 reflects light propagating through the light guide body 14. In addition, light that is incident from the first main surface 14 a but is not absorbed by the optical functional material and is emitted from the second main surface 14 b is also reflected toward the inside of the light guide 14.

  As the reflective layer 15, 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) can be used. The reflection layer 15 may be a specular reflection layer that specularly reflects incident light, or may be a scattering reflection layer that scatters and reflects incident light. When a scattering reflection layer is used for the reflection layer 15, the amount of light that goes directly in the direction of the solar cell element 16 increases, so that the light collection efficiency to the solar cell element 16 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. In addition, as a scattering reflection layer, micro foaming PET (polyethylene terephthalate) (made by Furukawa Electric) etc. can be used.

  According to the solar cell module 11D of the present embodiment, the light that travels from the inside of the light guide body 14 toward the outside of the light guide body 14 by the reflective layer 15, is incident from the first main surface 14a, and is absorbed by the optical functional material. Instead, the light emitted from the second main surface 14 b is reflected toward the inside of the light guide 14. Therefore, it is suppressed that most of the sunlight incident on the light guide body 14 leaks outside before reaching the solar cell element 16. Therefore, most of the sunlight incident on the light guide 14 can be contributed to power generation.

Further, since the reflected light is scattered by using the scattering reflection layer for the reflection layer 15, a part of the external light incident on the first main surface 14 a of the light guide 14 is absorbed by the dichroic fluorescent dye 12. The ratio increases.
When the dichroic fluorescent dye 12 absorbs a part of the external light, the dichroic fluorescent dye 12 emits light anisotropically, and the light having the highest light emission intensity emitted from the dichroic fluorescent dye 12 is directly guided to the solar cell element 16. It is burned. Therefore, most of the sunlight incident on the light guide 14 can be contributed to power generation.

[Sixth Embodiment]
FIG. 24 is a cross-sectional view of the solar cell module 11E of the sixth embodiment. The basic configuration of the solar cell module 11E of the present embodiment is the same as that of the fifth embodiment, and is different from the fifth embodiment in that a diffusion plate 13 is provided on the second main surface 14b side of the light guide 14. In FIG. 24, about the structure which is common in the solar cell module 11D of 5th Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  As shown in FIG. 24, in the solar cell module 11E of the present embodiment, the reflective layer 15 is provided on the second main surface 14b side of the light guide 14 via an air layer. That is, the solar cell module 11E of the present embodiment has a configuration in which the diffusion plate 13 is provided on the first main surface 14a side of the light guide body 14 according to the fourth embodiment in the configuration of the third embodiment. The configuration is a combination of the configuration in which the reflective layer 15 is provided on the second main surface 14b side of the light guide body 14 according to the embodiment.

  Also in the solar cell module 11E of the present embodiment, the same effects as those of the fourth embodiment and the fifth embodiment can be achieved, such that most of the sunlight incident on the light guide body 14 can be contributed to power generation. In the present embodiment, since the diffusing plate 13 and the reflective layer 15 are provided, the above effect is remarkable.

[Seventh Embodiment]
FIG. 34 is a cross-sectional view of the solar cell module 11H of the seventh embodiment. The basic configuration of the solar cell module 11H of the present embodiment is the same as that of the fifth embodiment, and a quarter λ plate 19 is provided between the second main surface 14b of the light guide 14 and the reflective layer 15. Is different from the fifth embodiment. In FIG. 34, about the structure which is common in solar cell module 11D of 5th Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  As shown in FIG. 24, in the solar cell module 11E of the present embodiment, the quarter λ plate 19 is provided between the second main surface 14b of the light guide 14 and the reflective layer 15 via an air layer. It has been. That is, the ¼λ plate 19 is adjacent to the second main surface 14b of the light guide 14 through the air layer. The quarter λ plate 19 is adjacent to the reflective layer 15 through an air layer.

  Light propagation in the case where the ¼λ plate 19 is provided between the second main surface 14b of the light guide 14 and the reflective layer 15 will be described with reference to FIGS. 35A to 35E.

  Since the dichroic fluorescent dye 12 is vertically aligned, the light guide 14 does not function as a polarizing plate for light incident in parallel to the Z axis, but does not function as light incident obliquely to the Z axis. On the other hand, it functions as a polarizing plate. Therefore, as shown in FIGS. 35A and 35B, when the non-polarized sunlight L passes through the light guide body 14, it becomes linearly polarized light L11. As shown in FIG. 35C, the linearly polarized light L11 passes through the ¼λ plate 19 to become circularly polarized light L12. As shown in FIG. 35D, the circularly polarized light L12 is reflected by the reflective layer 15, and becomes circularly polarized light L13 having a different optical rotation direction from the circularly polarized light 12. As shown in FIG. 35E, the circularly polarized light L13 is incident on the ¼λ plate 19 again to become the linearly polarized light L14. However, the linearly polarized light L14 has a deflection direction different from that of the linearly polarized light L11 (ideally 90 °). Different). Therefore, the linearly polarized light L14 is easily absorbed by the dichroic fluorescent dye 12 as compared with the light emitted from the light guide 14 and reflected by the reflective layer 15 without passing through the ¼λ plate 19.

  In the present embodiment, the ¼λ plate 19 is used. However, the present embodiment is not limited to this, and other retardation plates may be used. For example, instead of the 1 / 4λ plate 19, a 1 / 8λ plate, a 5 / 8λ plate, a 3 / 4λ plate, or the like may be used.

  As in the fifth embodiment, the reflection layer 15 may be a scattering reflection layer.

  Also in the solar cell module 11H of the present embodiment, the same effects as those of the fourth embodiment and the fifth embodiment can be achieved, such that most of the sunlight incident on the light guide 14 can be contributed to power generation. In the present embodiment, since the reflection layer 15 and the ¼λ plate 19 are provided, the above-described effect becomes remarkable.

[Eighth Embodiment]
FIG. 25 is a cross-sectional view of the solar cell module 11F of the eighth embodiment. The basic configuration of the solar cell module 11F of the present embodiment is the same as that of the third embodiment, and two types of dichroic fluorescent dyes (first dichroic fluorescent dye 112a and second dichroic dye are provided inside the light guide body 14. The third embodiment is different from the third embodiment in that a fluorescent fluorescent dye 112b) is provided. In FIG. 25, about the structure which is common in the solar cell module 11B of 3rd Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  In the solar cell module 11B of the third embodiment, a part of the external light L incident on the first main surface 14a is converted into a plurality of second optical functional materials (first phosphor 18a, second phosphor 18b, third phosphor). 18c), energy transfer was caused by the Forster mechanism between the plurality of second optical functional materials. Then, the light emitted from the second optical functional material (third phosphor 18c) having the largest peak wavelength of the emission spectrum is enhanced in directivity by the dichroic fluorescent dye 12 (first optical functional material), and the light guide 14 was condensed on the end face 14 c of the solar cell element 16 and made incident on the solar cell element 16.

  On the other hand, in the solar cell module 11F of the present embodiment, a part of the external light L incident on the first main surface 14a is converted into a plurality of second optical functional materials (first phosphor 18a, second phosphor 18b, first 3 phosphor 18c), and energy transfer is caused by the Förster mechanism between some second optical functional materials of the plurality of second optical functional materials. Then, the light emitted from the second optical functional material having the largest peak wavelength of the emission spectrum is enhanced in directivity by the first dichroic fluorescent dye 112a (first optical functional material) and applied to the end face 14c of the light guide body 14. The light is condensed and made incident on the solar cell element 16. Furthermore, energy transfer is caused by the photoluminescence mechanism between the remaining second optical functional materials of the plurality of second optical functional materials. Then, the light emitted from the second optical functional material having the largest peak wavelength of the emission spectrum is enhanced in directivity by the second dichroic fluorescent dye 112b (first optical functional material) and applied to the end face 14c of the light guide body 14. The light is condensed and made incident on the solar cell element 16. That is, in this embodiment, both energy transfer by the Forster mechanism and energy transfer by the photoluminescence mechanism are caused.

Also in the solar cell module 11F of the present embodiment, the same effect as that of the third embodiment, in which most of the sunlight incident on the light guide body 14 can be contributed to power generation, is achieved. Furthermore, in this embodiment, by using two types of dichroic fluorescent dyes 112a and 112b, external light incident on the first major surface 14a by energy transfer by the photoluminescence mechanism in addition to energy transfer by the Forster mechanism. It is possible to propagate energy.
Therefore, a solar cell module with high power generation efficiency can be provided.

[Ninth Embodiment]
FIG. 26 is a cross-sectional view of the solar cell module 11G of the ninth embodiment.
FIG. 27 is a diagram illustrating an emission spectrum of an optical functional material used in the solar cell module 11G of the ninth embodiment and a spectral sensitivity of the solar cell element.
The basic configuration of the solar cell module 11G of this embodiment is the same as that of the first embodiment, and two types of phosphors (first phosphor 18d and second phosphor 18e) are provided inside the light guide body 14. This is different from the first embodiment. In FIG. 26, about the structure which is common in the solar cell module 11 of 1st Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  In the solar cell module 11B of the third embodiment, as the plurality of second optical functional materials provided in the light guide 14, each of the three phosphors (the first phosphor 18a and the second phosphor) having a high fluorescence quantum yield. 18b, the third phosphor 18c) was used. On the other hand, in the solar cell module 11G of the present embodiment, as the plurality of second optical functional materials provided in the light guide, the first phosphor 18d having a low fluorescence quantum yield and the second having a high fluorescence quantum yield. A phosphor 18e is used. The first phosphor 18d is a host molecule, the second phosphor 18e is a guest molecule, energy transfer occurs due to the Forster mechanism between the first phosphor 18d and the second phosphor 18e, and substantially, Only the second phosphor 18e, which is a guest molecule, emits light. In the present embodiment, the light emitted from the second phosphor 18e is enhanced in directivity by the dichroic fluorescent dye 12 (first optical functional material) and condensed on the end surface 14c of the light guide 14 so as to be solar cells. The light is incident on the element 16.

  The first phosphor 18d is, for example, NPB (N, N-di (naphthalene-1-yl) -N, N-diphenyl-benzidene). The fluorescence quantum yield of the first phosphor 18d is 42%, and the peak wavelength 1161 of the emission spectrum of the first phosphor 18d is 430 nm. The second phosphor 18e is, for example, rubrene. The fluorescence quantum yield of the second phosphor 18e is a high fluorescence quantum yield close to 100%, and the peak wavelength of the emission spectrum 1162 of the second phosphor 18e is 560 nm. The content of the second phosphor 18e is 2% with respect to the first phosphor 18d. In the light guide of this embodiment, for example, an optical functional material layer including a first phosphor 18d and a second phosphor 18e is formed on a first main surface of a transparent light guide made of a glass substrate having a thickness of 2 mm. The film is formed to a thickness of 5 μm, and parylene is formed to a thickness of 1 μm as a transparent protective film on the surface of the optical functional material layer.

  As the solar cell element 16, an amorphous silicon solar cell is used. Comparing the spectral sensitivities 1163 of the amorphous silicon solar cells at the peak wavelengths of the emission spectra of the first phosphor 18d and the second phosphor 18e, at the peak wavelength of the emission spectrum of the second phosphor 18e having the largest peak wavelength of the emission spectrum. The spectral sensitivity of the amorphous silicon solar cell is larger than the spectral sensitivity of the amorphous silicon solar cell at the peak wavelength of the emission spectrum of the first phosphor 18d. Therefore, if an amorphous silicon solar cell is used as the solar cell element 16, power generation can be performed with high efficiency.

  In the solar cell module 11G of the present embodiment, the fluorescence quantum yield of the first phosphor 18d, which is a host molecule, is very small as 42%. However, in the energy transfer by the Forster mechanism, the final power generation amount is the guest It depends on the fluorescence quantum yield of the molecule and does not depend on the fluorescence quantum yield of the host molecule. Therefore, if only the guest molecule is composed of a phosphor having a high fluorescence quantum yield, the same power generation amount can be obtained even if the host molecule is composed of a phosphor having a low fluorescence quantum yield. In general, since a phosphor is used as a light emitter, a phosphor with a low fluorescence quantum yield cannot be used, but when only energy is directly transferred without emitting light as in this embodiment. Even if the fluorescence quantum yield is low, the final power generation amount does not change, so it can be used. In general, phosphors having a high fluorescence quantum yield are expensive, have low light resistance, and have a short lifetime, so that maintenance costs are high. On the other hand, phosphors with low fluorescence quantum yields are low in price, abundant in materials, high in light resistance, and long in life, so that maintenance costs can be reduced.

  As the first phosphor 18d, it is preferable to use a fluorescent quantum yield of less than 90%, more preferably a fluorescent quantum yield of 80% or less. In general, since the lifetime of a solar cell is the time until the conversion efficiency reaches 90% of the initial value, the time until the emission intensity of the phosphor decreases by 10% in the light guide can also be regarded as the lifetime. it can. Since the phosphor is normally premised on the use as a light emitter, a high fluorescence quantum yield of 100% to 90% is required as the fluorescence quantum yield. Therefore, the lifetime of the phosphor can be regarded as the time until the fluorescence quantum yield drops by 10% from the initial value, that is, the time until the fluorescence quantum yield drops from 90% to 81%. Therefore, a phosphor having a fluorescence quantum yield of 80% or less is not usually used, and even if such a phosphor exists, it can be obtained at a low cost as a phosphor with poor performance. Therefore, if such a phosphor with a low fluorescence quantum yield is used, a solar cell module with high power generation efficiency can be provided at low cost.

In the present embodiment, NPB is used as an example of the first phosphor 18d, but the first phosphor 18d is not limited to this. Other materials include N, N'-bis (3-methylphenyl) -N, N'-diphenyl- [1,1'-biphenyl] -4,4'-diamine (TPD), 4,4'-bis -[N- (1-naphthyl) -N-phenylamino] -biphenyl) (a-NPD), 4,4'-bis- [N- (9-phenanthyl) -N-phenylamino] -biphenyl (PPD), N , N, N ', N'-tetra-tolyl-1,1'-cyclohexyl-4,4'-diamine (TPAC), 1,1,4,4-tetraphenyl-1,3-butadiene (TPB), TCAP , Poly (N-vinylcarbazole) (PVK), 4,4 ', 4``-tri (N-carbazolyl) triphenylamine (TCTA), 1,3,5-tris [4- (3-methylphenylphenylamino) phenyl] benzene ( m-MTDAPB), 1,3,5-tris [N- (4-diphenylaminophenyl) phenylamino] benzene (p-DPA-TDAB), 4,4,4 ''-tris (3-methylphenylphenylamino) triphenylamine (m-MTDATA ), 4,4 ', 4``-tris (1-naphthylphenylamino) triphenylamine (1-TNATA), 4,4', 4 ''-tris (2-naphthylphenylamino) triphenylamine (2-TNATA), 1,3, 5-tris (4-tert-butylphenyl-1,3,4-oxadiazolyl) benzene (TPOB), tri (p-terphenyl-4-yl) amine (p-TTA), bis {4- [bis (4-methylphenyl ) amino] phenyl} oligothiophene (BMA-nT), 2,5-bis {4- [bis (4-methylphenyl) amino] phenyl} thiophene (BMA-1T), 5,5 ''-bis {4- [bis (4-meth ylphenyl) amino] phenyl} -2,2'-bithiophene (BMA-2T), 5,5 ''-bis {4- [bis (4-methylphenyl) amino] phenyl} -2,2 ': 5', 2 '' -terthiophene (BMA-3T), 5,5 '''-bis {4- [bis (4-methylphenyl) amino] phenyl} -2,2': 5 ', 2'':5'', 2 '' -quaterthiophene (BMA-4T),
2- (4-biphenyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole (PBD), 2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline (BCP), 4,7-diphenyl-1,10-phenanthroline (Bphen), 2,9-bis (naphthalen-2-yl) -4,7-diphenyl-1,10-phenanthroline (NBphen), 1,3-bis [2 -(4-tert-butylphenyl) -1,3,4-oxadiazo-5-yl] benzene (OXD-7), 3- (4-biphenyl) -4-phenyl-5-tert-butylphenyl-1,2, 4-triazole (TAZ), 4,4'-bis (4,6-diphenyl-1,3,5-triazin-2-yl) biphenyl (BTB), 2,5-Bis (1-naphthyl) -1, 3,4-oxadiazole (BND), 4,4'-bis (carbazol-9-yl) biphenyl (CBP), 2,2 ', 7,7'-tetrakis (carbazol-9-yl) -9,9- spirobifluorene (Spiro-CBP), 1,3,5-tris (carbazol-9-yl) benzene (TCP), 1,3-bis (carbazol-9-yl) benzene (MCP),
Organic phosphors such as 4,4'-di (triphenylsilyl) -biphenyl (BSB), 1,4-bis (triphenylsilyl) benzene (UGH-2), 1,3-bis (triphenylsilyl) benzene (UGH-3) Inorganic phosphors composed of quantum dots composed of ZnO, CdSe, ZnSe, AlN, GaN, InN, InP, GaP, GaAs, ZnS, CdS, and the like, but are not limited thereto. In the present embodiment, an organic-inorganic hybrid phosphor (for example, an organometallic complex) may be used.

  In the present embodiment, the host molecule is composed of only one type of second optical functional material (first phosphor 18d). However, two or more types of second optical functional material can be used as the host material. In that case, the final power generation amount is determined by the fluorescence quantum yield of the second optical functional material having the largest peak wavelength of the emission spectrum. Therefore, it is desirable that the fluorescence quantum yield of the second optical functional material having the largest peak wavelength of the emission spectrum is higher than the fluorescence quantum yield of any other second optical functional material provided in the light guide.

[Tenth embodiment]
FIG. 28 is a diagram illustrating an emission spectrum of an optical functional material used in the solar cell module of the tenth embodiment and a spectral sensitivity of the solar cell element.

  In the solar cell module of the ninth embodiment, the first phosphor 18d having a fluorescence quantum yield of 42% is used as the host molecule. On the other hand, in the solar cell module of the present embodiment, a first phosphor having a fluorescence quantum yield of 3% is used as a host molecule. The first phosphor can be regarded as a non-light emitter that has a very low fluorescence quantum yield and does not emit light substantially. The first phosphor is a host molecule, the second phosphor is a guest molecule, energy transfer occurs by the Forster mechanism between the first phosphor and the second phosphor, and is substantially a guest molecule. Only the second phosphor emits light.

  The first phosphor is, for example, TPDS (N, N, N ′, N′-tetra-tolyl-1,1′-diphenylsulphide-4,4′-diamine). The fluorescence quantum yield of the first phosphor is 3%, and the peak wavelength of the emission spectrum 1171 of the first phosphor is 420 nm. The second phosphor of the present embodiment is the same rubrene as the second phosphor of the eighth embodiment. Reference numeral 1172 indicates the emission spectrum of the second phosphor. The content of the second phosphor is 3% with respect to the first phosphor. In the light guide of this embodiment, for example, an optical functional material layer including a first phosphor and a second phosphor is formed on a first main surface of a transparent light guide made of a glass substrate having a thickness of 2 mm. The film is formed with a thickness, and parylene is formed with a thickness of 1 μm as a transparent protective film on the surface of the optical functional material layer.

  As the solar cell element, an amorphous silicon solar cell is used. Comparing the spectral sensitivity 1173 of the amorphous silicon solar cell at the peak wavelength of the emission spectrum of the first phosphor and the second phosphor, the amorphous silicon at the peak wavelength of the emission spectrum 1172 of the second phosphor having the largest peak wavelength of the emission spectrum The spectral sensitivity 1173 of the solar cell 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 phosphors) provided in the light guide. Therefore, if an amorphous silicon solar cell is used as the solar cell element, power generation can be performed with high efficiency.

  According to this embodiment, a phosphor having a low fluorescence quantum yield such as the first phosphor (for example, TPDS) can be obtained at low cost and has high light resistance, so that a solar cell module with high power generation efficiency can be provided at low cost. .

[Eleventh embodiment]
FIG. 36 is a schematic perspective view of the solar cell module 21 of the eleventh embodiment.
In FIG. 36, the same reference numerals are given to configurations common to the solar cell module 11 of the first embodiment, and detailed description thereof is omitted.

  The solar cell module 21 includes a first light guide (fluorescent light guide) 22, a second light guide (shape light guide) 23, a first solar cell element 16, a second solar cell element 25, And a frame body 26. The first solar cell element 16 receives light emitted from the first end face 22 c of the first light guide 22. Hereinafter, the expression “exit” is also used in the same meaning as “injection”. The second solar cell element 25 receives light emitted from the second end surface 23 c of the second light guide 23. The frame 26 integrally holds the first light guide 22, the second light guide 23, the first solar cell element 16, and the second solar cell element 25. In the present embodiment, the direction parallel to the first main surface 22a of the first light guide 22 is the x-axis direction, the direction parallel to the first main surface 22a, and the x-axis direction. The direction orthogonal to the first axis is defined as the y-axis direction, and the direction orthogonal to the first main surface 22a (thickness direction of the first light guide 22) is defined as the z-axis direction.

  The first light guide 22 includes a first main surface 22a, a second main surface 22b, and a first end surface 22c. The first main surface 22a is a light incident surface on which external light L is incident. The second main surface 22b is located on the opposite side of the first main surface 23a. The first end surface 22c is a light exit surface. The second light guide 23 is disposed on the second main surface 22 b side of the first light guide 22. The second light guide 23 includes a first main surface 23a, a second main surface 23b, and a second end surface 23c. The first main surface 23a is a light incident surface on which light transmitted from the second main surface 22b is incident. The second main surface 23b is located on the opposite side of the first main surface 23a. The second end surface 23c is a light exit surface. The first light guide 22 and the second light guide 23 are arranged such that the second main surface 22b of the first light guide 22 and the first main surface 23a of the second light guide 23 face each other. The light guide 22 and the second light guide 23 are stacked in the Z direction via an air layer K (low refractive index layer) having a refractive index smaller than that of the second light guide 23.

  The first main surface 22a of the first light guide 22 and the first main surface 23a of the second light guide 23 are arranged to face each other in the same direction (light incident side: -Z direction). Thus, the 1st light guide 22 and the 2nd light guide 23 are laminated | stacked along the incident direction of the light L, The 1st light guide of the front | former stage side (side near the side into which the light L injects). The light that could not be captured at 22 can be captured by the second light guide 23 on the rear stage side (the side far from the side where the light L is incident).

  Further, the first end surface 22c of the first light guide 22 and the second end surface 23c of the second light guide 23 face the same direction. The first end face 22c of the first light guide 22 and the second end face 23c of the second light guide 23 are arranged on the same plane parallel to the XZ plane. Accordingly, the first solar cell element 16 that receives light emitted from the first end face 22c of the first light guide 22 and the second sun that receives light emitted from the second end face 23c of the second light guide 23 are received. The battery element 25 is arranged in one place. In addition, it is preferable that these solar cell elements 16 and 25 are optically bonded to the corresponding end face 22c (23c).

  The first light guide 22 is a substantially rectangular plate-like member having a first main surface 22a and a second main surface 22b perpendicular to the Z axis (parallel to the XY plane). The first main surface 22a and the second main surface 22b of the first light guide 22 are flat surfaces substantially parallel to the XY plane. In the present embodiment, the first light guide 22 is obtained by dispersing the anisotropic light functional material 12 inside a transparent substrate made of a liquid crystalline polymer as shown in FIG.

  The anisotropic optical functional material 12 can be the same as the first optical functional material 12 of the first embodiment. That is, the anisotropic light functional material 12 is a material having a property of emitting light anisotropically (light emission anisotropy), and a dichroic fluorescent dye is used in the present embodiment. The dichroic fluorescent dye is a dye having both the property of absorbing light anisotropically (absorption anisotropy) and the property of emitting light anisotropically (light emission anisotropy). In the present embodiment, as the dichroic fluorescent dye (anisotropic optical functional material 12), a positive dichroic fluorescent dye in which the direction orthogonal to the molecular long axis is the direction with the highest emission intensity is used.

The dichroic fluorescent dye is not limited to the positive dichroic fluorescent dye, and various dichroic fluorescent dyes can be used. For example, a negative dichroic fluorescent dye in which the direction of the molecular long axis is the direction in which the emission intensity is the highest can also be used.
Such a dichroic fluorescent dye absorbs, for example, ultraviolet light or visible light and emits visible light or infrared light. The light emitted from the dichroic fluorescent dye is a first light guide. It propagates through the inside of the body 22 and is emitted from the first end face 22 c and is used for power generation by the first solar cell element 16.

  The dichroic fluorescent dye used as the anisotropic light functional material 12 of the present embodiment has the characteristics shown in FIG. In addition, the dichroic fluorescent dye of the present embodiment exhibits a light distribution state similar to that of the dichroic fluorescent dye of the first embodiment. Specifically, the dichroic fluorescent dye exhibits an orientation state as shown in FIG. In addition, the light guide 14, the first main surface 14a, and the second main surface 14b illustrated in FIG. 4 correspond to the first light guide 22, the first main surface 22a, and the second main surface 22b of the present embodiment, respectively. . As shown in FIG. 4, the dichroic fluorescent dye 12 of the present embodiment is oriented so that the axis V2 orthogonal to the molecular long axis and the first main surface 22a of the first light guide 22 are parallel to each other. Yes. That is, in the dichroic fluorescent dye 12 of this embodiment, the direction in which the emission intensity of the light emitted from the dichroic fluorescent dye 12 is largest is parallel to the first main surface 22a of the first light guide 22. Are oriented as follows.

  In addition, the 1st light guide 22 of this embodiment is a substantially rectangular plate-shaped member which has the 1st main surface 22a and the 2nd main surface 22b perpendicular | vertical (parallel to XY plane) to a Z-axis. Therefore, the dichroic fluorescent dye 12 of this embodiment is oriented so that the axis V2 orthogonal to the molecular long axis and the second major surface 22b of the first light guide 22 are parallel. That is, in the dichroic fluorescent dye 12 of this embodiment, the direction in which the emission intensity of the light emitted from the dichroic fluorescent dye 12 is the highest is parallel to the second main surface 22b of the first light guide 22. Are oriented as follows.

  The method for aligning the dichroic fluorescent dye 12 and the method for verifying the alignment state of the dichroic fluorescent dye 12 are the same as those described in the first embodiment.

  As shown in FIG. 5B, the dichroic fluorescent dye 12 emits light anisotropically by the excitation energy of external light incident from the first main surface 22a. The dichroic fluorescent dye 12 of the present embodiment is oriented so that the direction in which the light emission intensity of the light emitted from the dichroic fluorescent dye 12 is the largest is parallel to the first main surface 22a of the first light guide 22. Has been. Therefore, light having the highest emission intensity among the light emitted from the dichroic fluorescent dye 12 is directly guided to the first solar cell element 16.

As shown in FIG. 5C, most of the light emitted from the dichroic fluorescent dye 12 has a large incident angle θ on the first main surface 22a or the second main surface 22b of the first light guide 22. Become.
Here, for example, when the refractive index of the liquid crystalline polymer constituting the first light guide 22 is 1.5 and the refractive index of air is 1.0, the critical angle on the first main surface 22a of the first light guide 22 is set. θm, that is, the critical angle at the interface between the liquid crystalline polymer constituting the first light guide 22 and air is about 42 ° from Snell's law. When a part of the light L1 emitted from the dichroic fluorescent dye 12 is incident on the first main surface 22a, the incident angle of the light L1 on the first main surface 22a is larger than 42 ° which is a critical angle. Since the total reflection condition is satisfied, the light L is totally reflected by the first main surface 22a. Thereafter, the light L1 is repeatedly reflected between the first main surface 22a and the second main surface 22b, and is guided to the first solar cell element 16.

  In the dichroic fluorescent dye 12 of the present embodiment, the direction in which the emission intensity of light emitted from the dichroic fluorescent dye 12 is the smallest is the first main surface 22a and the second main surface of the first light guide 22. 22b is orthogonal to each other. When light L2 from the direction along the molecular long axis of light emitted from the dichroic fluorescent dye 12 is incident on the second main surface 22b, the incident angle of the light L2 on the second main surface 22b is a critical angle 42. The light L2 is emitted to the second light guide 23 side because it becomes smaller than ° and does not satisfy the total reflection condition.

  That is, the light emitted from the dichroic fluorescent dye 12 is confined in the first light guide 22 when the incident angle to the first main surface 22a or the second main surface 22b is larger than the critical angle, and the first When the incident angle to the main surface 22a or the second main surface 22b is smaller than the critical angle, the light is emitted to the outside. In the present embodiment, the dichroic fluorescent dye 12 is oriented so that the direction in which the emission intensity of the light emitted from the dichroic fluorescent dye 12 is maximum is parallel to the first main surface 22a of the first light guide 22. Has been. Therefore, most of the light emitted from the dichroic fluorescent dye 12 has a large incident angle θ on the first main surface 22a or the second main surface 22b of the first light guide 22, and the total reflection condition. Will be satisfied. Therefore, most of the light emitted from the dichroic fluorescent dye 12 is confined inside the first light guide 22 and propagates toward the first solar cell element 16 without being emitted outside. .

  Here, “propagating” means that the first main surface 22a is reflected on the first end surface 22c, the second main surface 22b is reflected on the first end surface 22c, and the first main surface 22a is reflected on the first main surface 22a. It means either the case where the first end surface 22c is reached while being reflected by both of the second main surfaces 22b, or the case where the first end surface 22c is reached without hitting any of the main surfaces 14a, 14b.

As shown in FIGS. 36 and 37, light (fluorescent light) emitted (emitted) from the anisotropic light functional material 12 (dichroic fluorescent dye) is formed on the end surface of the first light guide 22 other than the first end surface 22c. ) Is provided.
As the reflective layer 28, 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 Specular Reflector) reflective film (manufactured by 3M) can be used. The reflection layer 28 may be a specular reflection layer that specularly reflects incident light, or may be a scattering reflection layer that scatters and reflects incident light.

  The second light guide 23 is a substantially rectangular plate-like member having a first main surface 23a perpendicular to the Z-axis (parallel to the XY plane) and a second main surface 23b opposite to the first main surface 23a. It is. As the second light guide 23, a highly transparent organic material or inorganic material such as acrylic resin, polycarbonate resin, or glass is used.

  The second main surface 23b of the second light guide 23 is provided with a plurality of grooves T extending in the X direction. The groove T is a V-shaped groove having an inclined surface T1 that is inclined with respect to a plane parallel to the XY plane and a surface T2 that intersects the inclined surface T1. In FIG. 36, only a few grooves T are shown in order to simplify the drawing, but in practice, a large number of fine grooves T having a width of about 100 μm are formed. The groove T is formed, for example, by injection molding a resin (for example, polymethyl methacrylate resin: PMMA) using a mold.

As shown in FIG. 38A, the inclined surface T1 totally reflects the light L2 incident from the first main surface 23a (the light L2 transmitted from the first light guide 22), and the traveling direction of the light is directed to the second end surface 23c. It is a reflective surface that changes in the direction it heads. The light L2 incident at an angle close to perpendicular to the first main surface 23a is reflected by the inclined surface T1 and propagates in the second light guide 23 in the Y direction. Based on such a configuration, the second light guide 23 is a shape light guide that reflects and propagates light at the inclined surface T1 provided on the second main surface 23b and emits the light from the second end surface 23c. ing.
A plurality of such grooves T are provided in the Y direction on the second main surface 23b of the second light guide 23 so that the inclined surfaces T1 and T2 are in contact with each other. The shapes and sizes of the plurality of grooves T provided on the second main surface 23b are all the same.

In the example shown in FIG. 38A, the inclination angle θ of the inclined surface T1 is 30 °, the width w in the Y direction of one groove T is 100 μm, and the depth d in the Z direction of the groove T is 90 μm. And the refractive index of the second light guide 23 is 1.5. However, the inclination angle θ, the width w of the groove T, the depth d of the groove T, and the refractive index of the second light guide 23 are of course not limited thereto.
For example, as shown in FIG. 38B, the groove T may have a symmetrical V-shape and the inclination angle θ may be 40 °. In that case, it is preferable to arrange the second solar cell element 25 also on the end surface 23d opposite to the second end surface 23c. Further, a reflective layer may be provided instead of the second solar cell element 25.

In the present embodiment, although not shown, the second light guide is provided from the end face to the end face other than the second end face 23c (23d) of the second light guide 23, that is, the end face where the second solar cell element 25 is not disposed. A reflection layer is provided that reflects light leaking out of the body 23 to the inside of the second light guide 23. As these reflective layers, the same layers as those of the reflective layer 28 are used.
The first light guide 22 and the second light guide 23 have an air layer K interposed between them as shown in FIG. 37, but they may be in contact with each other by adhesion or the like. . However, if the air layer K is interposed between the first light guide 22 and the second light guide 23, the light emitted from the dichroic fluorescent dye (anisotropic light functional material 12) is transmitted to the first light guide. The total reflection condition is easily satisfied at the interface between the air layer 22 and the air layer, which is preferable.

As the 1st solar cell element 16 and the 2nd solar cell element 25, well-known solar cells, such as a silicon type solar cell, a compound type solar cell, a quantum dot solar cell, and an organic type solar cell, can be used. Among these, compound solar cells and quantum dot solar cells using compound semiconductors are suitable as these solar cell elements 4 and 5 because they can generate power with high efficiency. Examples of compound solar cells include InGaP, GaAs, InGaAs, AlGaAs, Cu (In, Ga) Se ₂ , Cu (In, Ga) (Se, S) ₂ , CuInS ₂ , CdTe, CdS, and the like. Examples of the quantum dot solar cell include Si and InGaAs.

  However, other types of solar cells such as Si and organic can be used depending on the price and application. In addition, the first solar cell element 16 and the second solar cell element 25 are appropriately solar cell elements that can perform photoelectric conversion with higher efficiency corresponding to the wavelength range of light emitted from the light guides 14 and 23. It is preferable to select and use. However, it goes without saying that the same type of solar cell element may be used.

As shown in FIG. 36, the frame body 26 is made of a frame such as aluminum, and the first main surface 22a of the first light guide 22 is exposed to the outside, and the first light guide 22 and the second light guide are in that state. While holding the four circumferences of the body 23, the first solar cell element 16 and the second solar cell element 25 are also held together with the light guides 14 and 23.
A transparent member such as glass may be fitted into the opening 26a that allows the first main surface 22a of the first light guide 22 to face the outside. With this configuration, the first light guide 22 has a first main surface 22a facing the outside from the frame 26 as a light incident surface. Further, the first end face 22c of the first light guide 22 and the second end face 23c of the second light guide 23 are light emission surfaces.

  As described above, in the solar cell module 21 of the present embodiment, the dichroic fluorescent dye (anisotropic light functional material 12) is included in the first light guide 22, and emitted from the dichroic fluorescent dye 12. The direction in which the emission intensity of the emitted light is the largest is oriented so as to face the first end face 22c of the first light guide 22 on which the first solar cell element 16 is disposed. That is, the direction in which the emission intensity is the largest among the light emitted from the dichroic fluorescent dye 12 is parallel to the first main surface 22a of the first light guide 22, and therefore the direction in which the emission intensity is the highest and the first light guide. 22 is oriented so that the angle formed with the normal line of the first major surface 22a at 22 is not less than the critical angle.

  Therefore, in the solar cell module 21 of the present embodiment, most of the external light (sunlight) incident on the first light guide 22 at a relatively large (deep) incident angle propagates to the first end face 22c side. To the first solar cell element 16. In addition, light incident on the first light guide 22 at an angle close to perpendicular (small incident angle) cannot be absorbed due to the absorption anisotropy of the dichroic fluorescent dye 12, and is transmitted through the second main surface 22b. However, the light emitted from the second main surface 22 b can be condensed by the second light guide 23 and guided to the second solar cell element 25. That is, since the angle of light incident on the second light guide 23 is mainly vertical light, the angle of the inclined surface T1 of the second light guide 23 which is a shape light guide is appropriately set. Thus, the light collection efficiency can be further increased. Therefore, according to the solar cell module 21 of the present embodiment, high power generation efficiency can be realized by increasing the light extraction efficiency.

  In the present embodiment, as shown in FIG. 36, the first solar cell element 16 is installed only on one end face (first end face 22c) with respect to the first light guide 22; One solar cell element 16 may be installed on a plurality of (2 to 4) end faces among the four end faces of the first light guide 22.

  Further, in the present embodiment, as the second light guide 23, a shape light guide that reflects and propagates light at the inclined surface T1 provided on the second main surface 23b and emits from the second end surface 23c is used. However, instead of such a shape light guide, a fluorescent light guide in which phosphors to be described later are dispersed may be used. As the fluorescent light guide, one using a dichroic fluorescent dye as the fluorescent material can be used. However, in that case, the dichroic fluorescent dye is not oriented in the same direction as the first light guide 22, that is, the direction with the highest emission intensity among the light emitted from the dichroic fluorescent dye is the second light guide. Preferably, the body 23 is oriented so that the direction with the highest emission intensity is directed to the first main surface 23a side to some extent without being parallel to the first main surface 23a.

[Twelfth embodiment]
FIG. 39 is a side sectional view showing a schematic configuration of a solar cell module 21A of the twelfth embodiment.
The solar cell module 21A of the present embodiment is different from the solar cell module 21 of the eleventh embodiment shown in FIGS. 36, 37, etc., in the solar cell module 21 of the eleventh embodiment of the first light guide body 22. The dichroic fluorescent dye (anisotropic light functional material 12) is arranged such that the direction in which the emission intensity is the largest among the light emitted from the dichroic fluorescent dye 12 is parallel to the first main surface 22a of the first light guide 22. In contrast, in this embodiment, the first light guide 22 is oriented so that the direction with the highest light emission intensity is not parallel to the first main surface 22a.

  As described above, the dichroic fluorescent dye 12 is oriented in a predetermined direction by the action of an orientation material (liquid crystalline polymer). However, the orientation control by this orientation material is in a desired direction (the direction in which the emission intensity is the largest in the light emitted from the dichroic fluorescent dye 12 is parallel to the first main surface 22a of the first light guide 22). Instead, it may be oriented slightly tilted. In this embodiment, the direction in which the emission intensity is the largest among the light emitted from the dichroic fluorescent dye 12 is not parallel to the first main surface 22a of the first light guide 22 but is slightly inclined and oriented. It is a case.

  As in the first embodiment, the dichroic fluorescent dye 12 may be distributed as shown in FIG. In addition, the light guide 14, the first main surface 14a, and the second main surface 14b of FIG. 6 correspond to the first light guide 22, the first main surface 22a, and the second main surface 22b of the present embodiment, respectively. As shown in FIG. 6, the angle θ formed by the axis V2 orthogonal to the molecular long axis V1 and the normal line of the first main surface 22a of the first light guide 22 is oriented so that the critical angle θm is not less than the critical angle θm. If so, it may be oriented slightly inclined with respect to the desired direction.

  In this embodiment in which the dichroic fluorescent dye 12 is oriented slightly inclined as described above, for example, when the solar cell module 21A is installed on a roof or the like and the first main surface 22a is arranged upward, the eleventh Compared to the embodiment, the solar light can be easily absorbed. That is, as shown in FIG. 39, the elevation angle θs of the sun S varies from about 30 ° to about 80 ° depending on the season in Japan, but the axis V2 shown in FIG. By arranging so as to face the sun, it is possible to easily absorb sunlight.

  However, in that case, by tilting the dichroic fluorescent dye 12, the amount of light transmitted from the second main surface 22b side without being totally reflected increases. However, in the present embodiment, since the second light guide 23 is provided behind the first light guide 22 (on the second main surface 22b side), the light transmitted from the second main surface 22b is second guided. The light is condensed by the light body 23 and can be generated by the second solar cell element 25. The most efficient one depends on the light emission profile of the dichroic fluorescent dye 12.

Further, since the light transmitted through the first light guide 22 enters the second light guide 23 at a certain angle, the reflection structure of the second light guide 23 (shape light guide) shown in FIG. 38A. That is, by forming the angle of the inclined surface T1 of the groove T according to this, the light collection efficiency can be further increased.
Therefore, according to the solar cell module 21A of the present embodiment, the inclination of the molecular major axis V1 is determined by taking into account the increase in the amount of absorption by tilting the dichroic fluorescent dye 12 and the decrease in the confinement rate. It is possible to achieve high power generation efficiency by increasing the extraction efficiency.

Also in the present embodiment, the first solar cell element 16 may be installed on a plurality of end faces of the first light guide 22.
Further, as the second light guide 23, a fluorescent light guide in which a phosphor is dispersed instead of the shape light guide, or a light guide using a dichroic fluorescent dye as the phosphor can be used.

[Thirteenth embodiment]
FIG. 40 is a side sectional view showing a schematic configuration of the solar cell module 21B of the thirteenth embodiment.
The solar cell module 21B of the present embodiment is different from the solar cell module 21 of the eleventh embodiment shown in FIGS. 36, 37, etc., in the solar cell module 21 of the eleventh embodiment of the first light guide body 22. While the anisotropic optical functional material 12 has only one type of dichroic fluorescent dye, in the present embodiment, the anisotropic optical functional material 12 of the first light guide 22 has two different absorption wavelength ranges. This is a point having (multiple types) of dichroic fluorescent dyes 12a and 12b (anisotropic optical functional material 12).

  Thus, since it has two types (plural types) of dichroic fluorescent dyes 12a and 12b (anisotropic light functional material 12) having different absorption wavelength ranges, the first light guide 22 has light in a wide wavelength range. Can be absorbed. As the dichroic fluorescent dyes 12a and 12b, for example, materials shown in the above formulas (1) and (2) can be used.

However, R in Formula (1) is H (hydrogen).
The dichroic fluorescent dye 12a represented by the formula (1) has an absorption wavelength of 396 nm and a fluorescence wavelength of 526 nm. Moreover, the dichroic fluorescent dye 12b shown in Formula (2) has an absorption wavelength of 516 nm and a fluorescence wavelength of 617 nm.
Incidentally, it is possible to use R in the formula (1), also obtained by substituting the _{O (CH 2) 7 CH 3} .

  Moreover, in the 1st light guide 22, the energy of the light which the dichroic fluorescent dye 12a absorbed, for example can be moved to the dichroic fluorescent dye 12b by repetition of light emission and absorption. Therefore, by continuously causing this energy transfer, light can be guided to the first solar cell element 16 with high efficiency by anisotropic light emission by the dichroic fluorescent dye 12b.

  Further, in the first light guide 22, the light absorbed by the dichroic fluorescent dye 12 a is transferred to the dichroic fluorescent dye 12 b, thereby guiding the light to the first solar cell element 16 with higher efficiency. it can. As the energy transfer, in particular, when the excitation energy is transferred by the Forster mechanism between the optical functional materials, the optical functional material having the largest peak wavelength of the emission spectrum can emit light.

  The mechanism for causing energy transfer between a plurality of types of optical functional materials, particularly the mechanism for causing energy transfer by the Forster mechanism, is as described with reference to FIGS. Although it is described that three kinds of general (commercially available) phosphors are used, the same forster is also obtained by using a plurality of types of dichroic fluorescent dyes 12 that are appropriately selected in this embodiment. It is possible to cause energy transfer by the mechanism. In addition, when the first light guide 22 includes other optical functional materials (including phosphors) together with the dichroic fluorescent dye 12, the same applies to the optical functional material and the dichroic fluorescent dye 12. It is possible to cause energy transfer by the Förster mechanism.

  In the example described with reference to FIGS. 12 to 15, the first light guide includes phosphors having three different emission spectra (first phosphor, second phosphor, and third phosphor). Regardless, due to the energy transfer by the Förster mechanism, substantially 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 first light guide, the light in the wavelength region up to 620 nm is absorbed, and the red having a peak wavelength of 630 nm with an efficiency of 92%. Can be emitted.

  As described with reference to FIGS. 16A and 16B of the first embodiment, such an energy transfer phenomenon is a phenomenon peculiar to an organic phosphor and generally does not occur in an inorganic phosphor. However, some inorganic nanoparticle phosphors such as quantum dots are known to cause energy transfer between inorganic materials or between an inorganic material and an organic material by a Forster mechanism.

  In addition, energy transfer by the Forster mechanism occurs not only in a light-emitting material such as a phosphor but also in a non-light-emitting body 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. 18 is a diagram showing a spectral sensitivity curve of an amorphous silicon solar cell which is an example of the first solar cell element 16 together with an emission spectrum of the first phosphor, an emission spectrum of the second phosphor, and an emission spectrum of the third phosphor. is there.

  The spectrum of the light L1 emitted from the end face of the first light guide 22 substantially matches the emission spectrum of the third phosphor. Therefore, a solar cell element should just have a high sensitivity in the peak wavelength (630 nm) of the emission spectrum of 3rd fluorescent substance. As shown in FIG. 18, 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 first solar cell element 16, power generation can be performed with high efficiency.

  The type of solar cell applied to the first solar cell element 16 is determined according to the wavelength of light incident on the solar cell element. In FIG. 18, an amorphous silicon solar cell is used as the first solar cell element 16, but the first solar cell element 16 is not limited to this.

  In the solar cell shown in FIG. 19 and FIG. 20, the spectral sensitivity and energy conversion efficiency of the solar cell at the peak wavelength (630 nm) of the emission spectrum of the third phosphor having the largest emission spectrum peak wavelength are provided in the light guide. It is larger than the spectral sensitivity and energy conversion efficiency of the solar cell at the peak wavelength of the emission spectrum of any of the other phosphors (the first phosphor and the second phosphor b). Therefore, if these solar cells are used as the first solar cell element 16, power generation can be performed with high efficiency.

  FIGS. 19 and 20 are examples of solar cells that can be used as the first solar cell element 16, and it is of course possible to use other solar cells. The first solar cell element 16, such as a dye-sensitized solar cell or an organic solar cell, cannot have high spectral sensitivity with respect to the entire wavelength region of sunlight, but is limited to light in a specific narrow wavelength region. On the other hand, it is possible to actively use a solar cell having a very high spectral sensitivity.

In the solar cell module 21B of the present embodiment, as the anisotropic light functional material 12 of the first light guide 22, two types (plural types) of dichroic fluorescent dyes 12a and 12b (different types) having different absorption wavelength ranges are used. Since it has the isotropic light functional material 12), the first light guide 22 can absorb light in a wide wavelength range. Therefore, the light extraction efficiency can be increased and high power generation efficiency can be realized.
In addition, the energy of light absorbed by one dichroic fluorescent dye 12a can be transferred to another dichroic fluorescent dye 12b by repetition of light emission and absorption, and thus this energy transfer is caused to continue. Thus, light can be guided to the first solar cell element 16 with high efficiency by anisotropic light emission by the dichroic fluorescent dye 12b.
Furthermore, the light emitted from the dichroic fluorescent dye having the largest peak wavelength of the emission spectrum can be obtained by appropriately selecting multiple types of dichroic fluorescent dyes and configuring the energy transfer by the Forster mechanism. The light can be emitted to the first end face 22 c of the first light guide 22 and incident on the first solar cell element 16. Therefore, the light extraction efficiency can be increased and high power generation efficiency can be realized.

In the present embodiment also, the first solar cell element 4 may be installed on a plurality of end surfaces of the first light guide 22.
Further, as the second light guide 23, a fluorescent light guide in which a phosphor is dispersed instead of the shape light guide, or a light guide using a dichroic fluorescent dye as the phosphor can be used.

[Fourteenth embodiment]
FIG. 41 is a side sectional view showing a schematic configuration of a solar cell module 21C of the fourteenth embodiment.
The solar cell module 21C of the present embodiment is different from the solar cell module 21 of the eleventh embodiment shown in FIGS. The solar cell module 21 of the eleventh embodiment has only one kind of anisotropic light functional material 12 (dichroic fluorescent dye) as the light functional material of the first light guide 22. On the other hand, in the present embodiment, the optical functional material of the first light guide 22 includes the anisotropic optical functional material 12 made of the dichroic fluorescent dye and the isotropic optical functional material 29 that absorbs light isotropically. doing. In FIG. 41, only one type of isotropic optical functional material 29 is shown, but this embodiment includes a case where there are a plurality of types of isotropic optical functional material 29.

The isotropic light functional material 29 has a property of absorbing light isotropically (absorption isotropic property) or a property of absorbing light anisotropically (absorption anisotropy). It is an optical functional material that is hardly oriented with respect to the material for forming the body 22 and is arranged in a random state. As this isotropic light functional material 29, it absorbs external light and emits fluorescence, and a phosphor having a predetermined absorption wavelength region is used. Here, any of organic phosphors, inorganic phosphors, organic-inorganic hybrid phosphors (for example, organometallic complexes) can be used as the phosphor.
Such an isotropic light functional material 29 and the dichroic fluorescent dye (anisotropic light functional material 12) are mixed, for example, when the first light guide 22 is molded, and are dispersed almost uniformly.

  Further, as the phosphor (isotropic light functional material 29), a material having the above-described energy transfer with the dichroic fluorescent dye (anisotropic light functional material 12) is appropriately selected and suitably used. Used. In that case, the dichroic fluorescent dye (anisotropic optical functional material 12) is preferably an optical functional material having the largest peak wavelength of the emission spectrum among the plural types of optical functional materials. FIG. 42 is a diagram showing how energy transfer occurs between the phosphor 29 (isotropic light functional material 29) and the dichroic fluorescent dye 12 (anisotropic light functional material 12). As shown in FIG. 42, a part of the external light incident on the first main surface 22 a of the first light guide 22 is absorbed by the phosphor 29. When the phosphor 29 absorbs part of the external light, the excitation energy moves from the phosphor 29 toward the dichroic fluorescent dye 12.

  Thereby, the dichroic fluorescent dye 12 emits light anisotropically as shown in FIG. 5B in the eleventh embodiment. The dichroic fluorescent dye 12 of the present embodiment is also oriented so that the direction in which the light emission intensity of the light emitted from the dichroic fluorescent dye 12 is the largest is parallel to the first main surface 22a of the first light guide 22. Has been. Therefore, light having the highest emission intensity among the light emitted from the dichroic fluorescent dye 12 is directly guided to the first solar cell element 16.

  As the phosphor (isotropic light functional material 29), the above-described ferrule is used between the dichroic fluorescent dye (anisotropic light functional material 12) or a plurality of kinds of phosphors (isotropic light functional material 29). More preferably, a material that causes energy transfer by a star mechanism is selected and used. For example, the first phosphor (Lumogen F Violet 570 (trade name) manufactured by BASF), the second phosphor (Lumogen F Yellow 083 (trade name) manufactured by BASF), and the third phosphor (manufactured by BASF) Lumogen F Red 305 (trade name)) can be used as the isotropic optical functional material 29. By dispersing the first phosphor, the second phosphor, and the third phosphor in the first light guide 22 together with the dichroic fluorescent dye (anisotropic light functional material 12), three types of isotropic light functional materials 29 are provided. It is preferable that energy transfer is caused by the Förster mechanism between them, and light obtained therefrom is absorbed by the dichroic fluorescent dye 12 to emit light.

  In the solar cell module 21C of the present embodiment, since the dichroic fluorescent dye (anisotropic light functional material 12) and the isotropic light functional material 29 are used in combination as the light functional material of the first light guide 22, By causing the isotropic light functional material 29 to perform energy transfer, light having a wide wavelength range and a wide angle can be absorbed. Therefore, the light extraction efficiency can be increased and high power generation efficiency can be realized.

  In the present embodiment, a phosphor having a predetermined absorption wavelength range that absorbs external light and emits fluorescence is used as the isotropic optical functional material 29. However, as the isotropic optical functional material in the present embodiment, It is not limited to this. As the isotropic optical functional material in the present embodiment, a light emitter that emits light in any form of fluorescence or phosphorescence can be used. Furthermore, a non-light-emitting optical functional material may be used as long as it causes energy transfer. However, a phosphor is used for the optical functional material having the largest peak wavelength in the fluorescence spectrum.

  In the present embodiment, the anisotropic optical functional material and the isotropic optical functional material are described as examples of separate molecules, but the fourteenth embodiment or a modification of the eleventh embodiment is the present embodiment. Alternatively, an optical functional material (anisotropic optical functional material) in which an absorbing portion and a light emitting portion exist in one molecule may be used. The light emitting part has light emission anisotropy, and the emitted light efficiently reaches the end face. The absorption part absorbs light isotropically, or has absorption anisotropy, but is oriented perpendicular to the light-emitting part or in a random state. . As such an optical functional material, for example, as shown in FIG. 33, a polymer main chain 1181 corresponds to a light emitting portion and a side chain 1182 corresponds to an absorbing portion.

Also in the present embodiment, the first solar cell element 16 may be installed on the plurality of end faces of the first light guide 22.
Further, as the second light guide 23, a fluorescent light guide in which a phosphor is dispersed instead of the shape light guide, or a light guide using a dichroic fluorescent dye as the phosphor can be used.

[Fifteenth embodiment]
FIG. 43 is a side sectional view showing a schematic configuration of a solar cell module 21D of the fifth embodiment.
The solar cell module 21D of this embodiment is different from the solar cell module 21 of the eleventh embodiment shown in FIGS. 36, 37, etc., as shown in FIG. 43, the first main surface 22a of the first light guide 22 The diffusion plate 13 is provided on the side.

The diffusing plate 13 is provided on the first main surface 22a side of the first light guide 22 via an air layer, and diffuses the external light incident from the outside of the first light guide 22 to make the first guide. The light is incident on the light body 22.
Since an air layer exists between the first light guide 22 and the diffusion plate 13, the light emitted from the dichroic fluorescent dye (anisotropic light functional material 12) is an interface between the first light guide 22 and the air layer. It becomes easy to satisfy the total reflection condition. However, the diffusion plate 13 may be brought into direct contact with the first main surface 22a of the first light guide 22 without interposing an air layer, or may be attached by adhesion or the like.

  The diffusing plate 13 is configured by dispersing a large number of light scattering bodies such as acrylic beads in a binder resin such as an acrylic resin. The thickness of the diffusion plate 13 is about 20 μm, for example, and the spherical diameter of the spherical light scatterer is about 0.5 to 20 μm. The diffuser plate 13 isotropically diffuses external light from the outside of the first light guide 22 toward the inside of the first light guide 22.

  The light scatterer is not limited to this, and the light scatterer described in the first embodiment can be used.

FIG. 44 is a diagram for explaining the operation of the diffusion plate.
In the case of the present embodiment, as shown in FIG. 44, the diffusion plate 13 is disposed on the first main surface 22a side of the first light guide 22. Thereby, the light incident perpendicularly to the solar cell module 21 </ b> D (the diffusion plate 13) is diffused by the diffusion plate 13 and then enters the first light guide 22. For this reason, light of various angles enters the dichroic fluorescent dye 12. That is, the proportion of light in a direction that is easily absorbed by the dichroic fluorescent dye 12 is larger than when the diffuser plate 13 is not provided. Therefore, the dichroic fluorescent dye 12 having an absorption characteristic that is relatively small in the direction along the molecular long axis V1 and relatively large in the direction along the axis V2 orthogonal to the molecular long axis. Even if it exists, it becomes possible to absorb a part of light which enters perpendicularly with respect to solar cell module 21D (diffusion plate 13).

  In the solar cell module 21D of the present embodiment, since the diffusion plate 13 is provided, two colors of external light incident on the first main surface 22a of the first light guide 22 are compared with the eleventh embodiment. The proportion absorbed by the fluorescent fluorescent dye 12 increases. The dichroic fluorescent dye 12 emits light anisotropically when it absorbs external light. Also in the dichroic fluorescent dye 12 of the present embodiment, the direction in which the emission intensity of the light emitted from the dichroic fluorescent dye 12 is the largest is parallel to the first main surface 22a of the first light guide 22. Since it is oriented, the light having the highest emission intensity among the light emitted from the dichroic fluorescent dye 12 is directly guided to the first solar cell element 16. Therefore, most of the sunlight incident on the first light guide 22 can be contributed to power generation. Therefore, high light generation efficiency can be realized by increasing light extraction efficiency.

  In addition, about the diffusion plate 13 which concerns on this embodiment, it combines with each solar cell module 21A-21D of 12th Embodiment-14th Embodiment, without applying only to the solar cell module 21 of 11th Embodiment. May be.

[Sixteenth Embodiment]
FIG. 45 is a side sectional view showing a schematic configuration of a solar cell module 21E of the sixth embodiment.
The solar cell module 21E of this embodiment is different from the solar cell module 21 of the eleventh embodiment shown in FIGS. 36, 37, etc., as shown in FIG. 44, the second main surface 23b of the second light guide 23. The reflective layer 15 is provided on the side.

The reflective layer 15 is provided on the second main surface 23b side of the second light guide 23 via an air layer or an adhesive layer, and the light transmitted through the second light guide 23 is secondly transmitted. The light is reflected inside the light guide 23.
As the reflective layer 15, the same one as the reflective layer 28 described above is used. That is, 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 Specular Reflector) reflective film (manufactured by 3M) can be used.
The reflection layer 15 may also be a mirror reflection layer that specularly reflects incident light, or a scattering reflection layer that scatters and reflects incident light. When a scattering reflection layer is used for the reflection layer 15, the amount of light directly going in the direction of the first solar cell element 16 increases, so that the light collection efficiency to the first solar cell element 16 increases and the amount of power generation increases. To do. In addition, since the reflected light is scattered, changes in the amount of power generation with time and season are averaged. In addition, as a scattering reflection layer, micro foaming PET (polyethylene terephthalate) (made by Furukawa Electric) etc. can be used.

In the solar cell module 21E of the present embodiment, since the reflective layer 15 is provided, the light transmitted from the second main surface 23b of the second light guide 23 is reflected again into the second light guide 23. be able to.
Therefore, the reflected light mainly passes through the second light guide 23 and re-enters the first light guide 22 where it is absorbed by the dichroic fluorescent dye 12 (anisotropic light functional material) and emitted. One solar cell element 16 can emit light. Therefore, most of the sunlight incident on the first light guide 22 can contribute to power generation, and the light extraction efficiency can be increased to achieve high power generation efficiency.
Further, if a scattering reflection layer is used as the reflection layer 15, the reflected light can be scattered, so that light incident again from the second main surface 22 b of the first light guide 22 is absorbed by the dichroic fluorescent dye 12. The ratio can be increased.

  In addition, about the reflective layer 15 which concerns on this embodiment, it combines with each solar cell module 21A-21E of 12th Embodiment-15th Embodiment, without applying only to the solar cell module 21 of 11th Embodiment. May be.

  Further, the quarter λ plate 19 described in the seventh embodiment may be provided between the second main surface 14 b of the light guide 14 and the reflective layer 15. With this configuration, light is more easily absorbed by the dichroic fluorescent dye 12 as compared with light emitted from the second light guide 23 and reflected by the reflective layer 15 without passing through the ¼λ plate 19. .

FIG. 46 is a side sectional view showing a schematic configuration of a solar cell module 21F configured by combining the solar cell module 21E of the fifteenth embodiment with the reflective layer 15 of the sixteenth embodiment.
As shown in FIG. 46, the diffusion plate 13 is provided on the first main surface 22 a side of the first light guide 22, and the reflective layer 15 is provided on the second main surface 22 b side of the second light guide 23. Therefore, even in this solar cell module 21F, as described in the fifth and sixth embodiments, most of the sunlight incident on the first light guide 22 is contributed to power generation, and light extraction is performed. High power generation efficiency can be realized by increasing the efficiency. Further, in the solar cell module 21 </ b> E, a ¼λ plate 19 may be further provided between the second main surface 14 b of the light guide 14 and the reflective layer 15.

[Seventeenth embodiment]
FIG. 47 is a side sectional view showing a schematic configuration of a solar cell module 21G of the seventeenth embodiment.
The solar cell module 21G of the present embodiment differs from the solar cell module 21 of the eleventh embodiment shown in FIGS. 36, 37, etc. in the following points. In the present embodiment, as shown in FIG. 47, the first solar cell element provided on the first end surface 22 c of the first light guide 22 and the second solar cell provided on the second end surface 23 c of the second light guide 23. The element is constituted by a common solar cell element, that is, a single solar cell element 212.

As the solar cell element 212 used in common, various solar cells used as the first solar cell element 16 and the second solar cell element 25 can be used. That is, known solar cells such as silicon solar cells, compound solar cells, quantum dot solar cells, and organic solar cells can be used.
Also in this embodiment, the first light guide 22 and the second light guide 23 may have an air layer interposed between them as shown in FIG. It may be. However, if an air layer is interposed between the first light guide 22 and the second light guide 23, the light emitted from the dichroic fluorescent dye (anisotropic light functional material 12) is emitted from the first light guide 22. It is easy to satisfy the total reflection condition at the interface between the air layer and the air layer, which is preferable.

  In the solar cell module 21G of the present embodiment, the solar cell element of the first light guide 22 and the solar cell element of the second light guide 23 are shared to form a single solar cell element 212. The overall configuration can be simplified and the cost can be reduced.

In the present embodiment, the first light guide 22 shown in the eleventh embodiment is used. Instead, the first light guide in any of the twelfth to fourteenth embodiments is used. The body 22 may be used. Moreover, it is good also as a structure provided with the any one or both of the diffuser plate 13 shown in 15th Embodiment, and the reflection layer 15 shown in 16th Embodiment.
Further, as the second light guide 23, a fluorescent light guide in which a phosphor is dispersed instead of the shape light guide, or a light guide using a dichroic fluorescent dye as the phosphor can be used.

[Eighteenth embodiment]
FIG. 29 is a cross-sectional view of the light guide 124 applied to the solar cell module of the eighteenth embodiment. The configuration other than the light guide 124 is the same as that of the solar cell module 11B of the third embodiment. Therefore, only the configuration of the light guide 124 will be described here. Moreover, about the structure which is common in the solar cell module 11B of 3rd Embodiment, the same code | symbol is attached | subjected and detailed description is abbreviate | omitted.

  The light guide 124 includes a transparent light guide 125, a fluorescent film 126 bonded to the first main surface 125 a of the transparent light guide 125, and a transparent protective film 127 that covers the surface of the fluorescent film 126. .

  The fluorescent film 126 is a film-like optical functional material layer in which the first fluorescent material 18a, the second fluorescent material 18b, and the third fluorescent material 18c are dispersed as the optical functional material described above. The fluorescent film 126 converts part of the external light (for example, sunlight) incident on the first main surface 126 a into fluorescence and radiates it toward the transparent light guide 125. For example, the phosphor film 126 includes a PMMA resin in which 0.2% of the first phosphor 18a, the second phosphor 18b, and the third phosphor 18c are mixed in a volume ratio with respect to the PMMA resin to form a film having a thickness of 200 μm. Formed.

  As the transparent light guide 125 and the transparent protective film 127, a highly transparent organic material or inorganic material such as acrylic resin, polycarbonate resin, or glass is used. For example, the transparent light guide 125 is made of an acrylic plate having a thickness of 5 mm, and the transparent protective film 127 is made of a PMMA resin film having a thickness of 200 μm. In FIG. 29, the transparent protective film 127, the fluorescent film 126, and the transparent light guide 125 are arranged in this order from the incident side of the external light L. However, as shown in FIG. You may arrange | position the transparent protective film 127 from the incident side of the external light L in this order.

  The transparent light guide 125 and the transparent protective film 127 are made of a highly transparent material that does not contain an optical functional material. Part of the fluorescence emitted from the fluorescent film 126 (light having a spectrum substantially the same as the emission spectrum of the third phosphor 18c shown in FIG. 14) is totally reflected inside the transparent light guide 125 and the transparent protective film 127. However, it propagates toward the end surfaces of the transparent light guide 125 and the transparent protective film 127. Light emitted from the end faces of the transparent light guide 125 and the transparent protective film 127 is incident on the solar cell element and used for power generation.

  The fluorescent film 126 and the transparent light guide 125 are bonded by a peelable adhesive layer 128 as shown in FIG. The fluorescent film 126 is peeled off from the transparent light guide 125 and replaced when damage, deterioration, or foreign matter (such as dust or bird droppings) adheres. The refractive indexes of the fluorescent film 126, the adhesive layer 128, and the transparent light guide 125 are all 1.49. The fluorescence emitted from the fluorescent film 126 propagates through the fluorescent film 126, the adhesive layer 128, and the transparent light guide 125 without loss. As such an adhesive layer 128, for example, Gel Poly (trade name) manufactured by Panac Corporation can be used.

  In the light guide 124 configured as described above, the fluorescent film 126 and the transparent light guide 125 are bonded to each other with a peelable adhesive layer 128. Therefore, when the fluorescent film 126 is damaged, deteriorated, or has foreign matter attached (such as dust or bird droppings) and power generation efficiency is reduced, only the fluorescent film 126 is peeled off from the transparent light guide 125 and replaced. Can do. Therefore, the maintenance cost can be reduced as compared with the case where the entire light guide is replaced.

[Nineteenth Embodiment]
FIG. 48 is a side sectional view showing a schematic configuration of the first light guide 220 applied to the solar cell module of the nineteenth embodiment. The configuration other than the first light guide 220 is the same as that of the solar cell module 21 of the eleventh embodiment. Therefore, only the configuration of the first light guide 220 will be described here.

The first light guide 220 includes a transparent light guide 221, a fluorescent film 222 bonded to the first main surface 221 a of the transparent light guide 221, and a transparent protective film 223 that covers the surface of the fluorescent film 222. ing.
The fluorescent film 222 is a film-like optical functional material layer in which a dichroic fluorescent pigment is dispersed as the anisotropic optical functional material 12 described above. In addition, a plurality of types of dichroic fluorescent dyes (anisotropic light functional material 12) may be dispersed in the fluorescent film 222. In addition to the anisotropic light functional material 12, the isotropic light functional material 29 described above. 1 type or multiple types may be disperse | distributed.

  The fluorescent film 222 converts a part of external light (for example, sunlight) incident on the first main surface 222a into fluorescence and radiates it toward the transparent light guide 221. The fluorescent film 222 is formed, for example, with a thickness of about 200 μm by dispersing the dichroic fluorescent dye 12 and the like inside a PMMA resin.

  As the transparent light guide 221 and the transparent protective film 223, a highly transparent organic material or inorganic material such as an acrylic resin, a polycarbonate resin, or glass is used. For example, the transparent light guide 221 is made of an acrylic plate having a thickness of 5 mm, and the transparent protective film 223 is made of a PMMA resin film having a thickness of 200 μm. In FIG. 48, the transparent protective film 223, the fluorescent film 222, and the transparent light guide 221 are arranged in this order from the incident side of the external light L. However, as shown in FIG. You may arrange | position the transparent protective film 223 from the incident side of the external light L in this order.

  The transparent light guide 221 and the transparent protective film 223 are made of a highly transparent material that does not contain an optical functional material. Part of the fluorescence emitted from the fluorescent film 222 propagates toward the end surfaces of the transparent light guide 221 and the transparent protective film 223 while totally reflecting the inside of the transparent light guide 221 and the transparent protective film 223. Light emitted from the end surfaces of the transparent light guide 221 and the transparent protective film 223 is incident on the first solar cell element and used for power generation.

  The fluorescent film 222 and the transparent light guide 221 are bonded together by a peelable adhesive layer 128 as shown in FIG. 31 in the eighteenth embodiment. That is, in FIG. 31, the fluorescent film 126 and the transparent light guide 125 correspond to the fluorescent film 222 and the transparent light guide 221 of this embodiment. The fluorescent film 222 is peeled off from the transparent light guide 221 and replaced when damage, deterioration, or foreign matter (such as dust or bird droppings) adheres. The refractive indexes of the fluorescent film 222, the adhesive layer 224, and the transparent light guide 221 are all 1.49. The fluorescence emitted from the fluorescent film 222 propagates through the fluorescent film 222, the adhesive layer 224, and the transparent light guide 221 without loss. As such an adhesive layer 224, for example, Gel Poly (trade name) manufactured by Panac Co., Ltd. can be used.

  In the 1st light guide 220 of the said structure, the fluorescent film 222 and the transparent light guide 221 are adhere | attached with the adhesive layer 224 which can peel. Therefore, when the fluorescent film 222 is damaged, deteriorated, or has foreign matter attached (such as dust or bird droppings) and the power generation efficiency is reduced, only the fluorescent film 222 is peeled off from the transparent light guide 221 and replaced. Can do. Therefore, the maintenance cost can be reduced as compared with the case where the entire first light guide is replaced.

[Solar power generator]
FIG. 32 is a schematic configuration diagram of the solar power generation device 11000.

  A solar power generation device 11000 includes a solar cell module 11001 that converts sunlight energy into electric power, an inverter (DC / AC converter) 11004 that converts DC power output from the solar cell module 11001 into AC power, A storage battery 11005 for storing DC power output from the battery module 11001.

The solar cell module 11001 includes a light guide body 1002 that condenses sunlight and a solar cell element 1003 that generates power using sunlight collected by the light guide body 1002.
As the solar cell module 11001, for example, the solar cell module described in the first to tenth embodiments is used.

  The solar power generation device 11000 supplies power to an external electronic device 11006. The electronic device 11006 is supplied with power from the auxiliary power source 11007 as necessary.

  Since the solar power generation device 11000 includes the solar cell module according to the above-described embodiment, the solar power generation device 11000 is a solar power generation device with high power generation efficiency.

  The technical scope of the aspect of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the aspect of the present invention.

  For example, the aspect of the present invention can be applied not only to the case where the first main surface and the second main surface of the light guide are parallel, but also to a configuration where the first main surface and the second main surface are not parallel. That is, the critical angle is the angle formed between the direction in which the emission intensity of light emitted from the first optical functional material (anisotropic optical functional material) is the largest and the normal of the first main surface of the light guide (first light guide). In the configuration in which the angle formed between the direction in which the emission intensity of the light emitted from the first optical functional material is the largest and the normal to the second main surface of the light guide is less than the critical angle The embodiments of the present invention can also be applied. Even in such a configuration, most of the sunlight incident on the light guide can be contributed to power generation.

For example, the material for forming the light guide (first light guide) is not limited to a liquid crystalline polymer, and a highly transparent organic material or inorganic material such as an acrylic resin, a polycarbonate resin, or glass can also be used.
Examples of the optical functional material include a phosphor that absorbs ultraviolet light or visible light and emits visible light or infrared light, or is excited by absorbing ultraviolet light or visible light, but emits light. A non-luminous material that deactivates without being included may be included. 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.

  It is desirable that the material of the base material (transparent substrate) of the light guide (first light guide, second light guide) be transparent to a wavelength of 400 nm or less so that external light can be taken in effectively. For example, a material having a transmittance of 90% or more, more preferably 93% or more with respect to light in a wavelength region of 360 nm to 800 nm is suitable. For example, in the case of a silicon resin substrate, a quartz substrate, or a PMMA resin substrate, “Acrylite” (registered trademark) manufactured by Mitsubishi Rayon is suitable because it has high transparency to light in a wide wavelength region. .

  In the above embodiment, the first optical functional material and the second optical functional material are described as examples of separate molecules, but the present invention is not limited thereto. For example, it includes those in which an absorption part and a light emission part exist in one molecule. The light emitting part has light emission anisotropy, and the emitted light efficiently reaches the end face. The absorption part absorbs light isotropically, or has absorption anisotropy, but is oriented perpendicular to the light-emitting part or in a random state. . For example, as shown in FIG. 33, the main chain 1181 of the polymer corresponds to the light emitting portion, and the side chain 1182 corresponds to the absorbing portion.

  The aspect of the present invention can be used for a solar cell module and a solar power generation device.

11, 11A, 11B, 11C, 11D, 11E, 11F, 11G ... solar cell module, 12 ... dichroic fluorescent dye (first optical functional material), 13 ... diffusion plate, 14 ... light guide, 14a ... first Main surface, 14b ... second main surface, 14c ... end surface, 15 ... reflective layer, 16 ... solar cell element, 18, 18a, 18b, 18c ... phosphor (second optical functional material), 124 ... light guide, 125 ... Transparent light guide, 125a ... First main surface, 126 ... Fluorescent film (optical functional material layer), 128 ... Adhesive layer, 11000 ... Solar power generator, L, L1, L2 ... Light

Claims (20)

A first main surface and a first end surface;
Including at least one optical functional material,
The at least one optical functional material includes a first optical functional material that emits light anisotropically,
At least light emitted from the first optical functional material is propagated and emitted from the end face;
The first optical functional material is oriented so that an angle formed by a direction in which the emission intensity of light emitted from the first optical functional material is maximum and a normal line of the first main surface is equal to or greater than a critical angle. Light guide.   The light guide according to claim 1, wherein the first optical functional material absorbs part of external light incident from the first main surface.   The light guide according to claim 1, further comprising a second optical functional material that isotropically absorbs part of the incident external light.   The second optical functional material has a property of absorbing light isotropically, or has a property of absorbing light anisotropically, but is difficult to be oriented with respect to the material included in the light guide body and is random. The light guide according to claim 3, which is one of the optical functional materials in a state. Including a plurality of the optical functional materials,
5. The light guide according to claim 1, wherein the first optical functional material includes an optical functional material having a maximum peak wavelength of an emission spectrum among the plurality of optical functional materials.   The first optical functional material is oriented so that the direction in which the light emission intensity of light emitted from the first optical functional material is the largest faces the end surface when viewed from the normal direction of the first main surface. Item 6. The light guide according to any one of Items 1 to 5.   The light guide according to any one of claims 1 to 6, wherein the first optical functional material includes an optical functional material made of a dichroic fluorescent dye.   The light guide according to claim 7, wherein the dichroic fluorescent dye includes a positive dichroic fluorescent dye in which the direction orthogonal to the molecular long axis is the direction having the highest emission intensity.   The light guide according to any one of claims 1 to 8, further comprising a diffusion plate that is provided on the first main surface side and diffuses external light incident from outside the light guide.   The energy transfer by the Forster mechanism is caused 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 emitted from the first end surface. The light guide according to any one of the above.   The optical functional material having a fluorescence quantum yield of 80% or less is included in one or more optical functional materials other than the optical functional material having the largest peak wavelength of the emission spectrum among the optical functional materials. The light guide according to any one of 3 to 10.   The light guide according to claim 11, wherein a fluorescence quantum yield of the optical functional material having the largest peak wavelength of the emission spectrum is higher than a fluorescence quantum yield of any other optical functional material included in the light guide. .   Furthermore, the light guide of any one of Claim 1 thru | or 12 containing the reflection layer which reflects the light which propagates the inside of the said light guide.   The light guide according to claim 13, further comprising a retardation plate between the light guide and the reflective layer.   The light guide according to claim 14, wherein the retardation plate is a ¼λ plate. A light guide according to any one of claims 1 to 15,
And a first solar cell element that receives the light emitted from the first end face of the light guide.   Among the optical functional materials, the spectral sensitivity of the first solar cell element at the peak wavelength of the emission spectrum of the optical functional material having the largest emission spectrum peak wavelength is any other optical functional material provided in the light guide. The solar cell module according to claim 16, wherein the solar cell module has a spectral sensitivity greater than a spectral sensitivity of the first solar cell element at a peak wavelength of the emission spectrum.   Furthermore, it has a 3rd main surface and a 2nd end surface, is arrange | positioned at the said 2nd main surface side, the light which permeate | transmitted from the said 2nd main surface enters from the said 3rd main surface, is propagated, and said 2nd end surface The solar cell module according to claim 16 or 17, further comprising: a second light guide that is emitted from the second light guide body; and a second solar cell element that is provided on the second end surface and receives light emitted from the second end surface. .   The anisotropic optical functional material is oriented so that a direction in which a light emission intensity of light emitted from the anisotropic optical functional material is maximum is directed to the first end surface when viewed from a normal direction of the first main surface. Item 19. The solar cell module according to Item 18.   20. The sun according to claim 18, wherein the second light guide is a shape light guide that reflects and propagates light at an inclined surface provided on the fourth main surface and emits the light from the second end surface. Battery module.

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