JP2010225692A - Solar cell and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solar cell which can efficiently collect sunlight to an photoelectric conversion element at a low cost while reducing environmental load. <P>SOLUTION: The solar cell has a light guide, in which core is covered with a clad. In the inside of the core, directional light emission particles which are oriented to extending direction are distributed. External light is entered in the light emission fine particles from the external and directivity is given, and the light is ejected into the core. The light turned in the core is totally reflected off an interface between the core and the clad and is guided to a photoelectric conversion part which converts the light into electric power. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

The present invention relates to a solar cell and a manufacturing method thereof.

In solar cells that are widely used at present, for example, amorphous silicon (CVD) formed on a large area semiconductor substrate such as silicon (Si) or a support substrate such as a glass substrate by chemical vapor deposition (CVD). A structure in which a photoelectric conversion layer is formed using a semiconductor thin film such as a-Si) is common. However, such a solar cell is extremely enormous in the manufacturing process of a large area suitable for the solar cell in the process of manufacturing the semiconductor substrate and the semiconductor thin film, for example, for melting at the time of manufacturing the semiconductor substrate and high vacuum in CVD. There is a problem of consuming energy. The power generation itself uses natural energy of sunlight, but it is important to reduce the environmental load during the manufacturing process in terms of life cycle assessment.

  For the solar cell having such a structure, for example, as disclosed in Patent Document 1, a solar cell system that guides sunlight and focuses it on a photoelectric conversion element has been proposed. This type of solar cell has the advantage that the area of individual solar cells can be significantly reduced. Therefore, in the solar battery according to the present method, it is not necessary to give photoelectric conversion characteristics to the structure that condenses on the solar battery cells, so that it can be characterized as being able to reduce the load during manufacturing.

JP-A-11-340493

  However, since the sunlight guiding / condensing method shown in Patent Document 1 uses a prism action, a relatively high-level process is required for producing a light guide plate for concentrating sunlight. Technology is needed. Further, in the structure using the prism action, efficient light guide can be realized for light rays having a constant incident angle with respect to the light guide plate. However, there is a problem that it is difficult to control the light guide angle for a light source whose light source position changes over time, such as sunlight. That is, for a certain angle of incidence, light can be guided and collected, but at an angle of incidence that deviates from the angle of incidence, light cannot be guided and efficiency is reduced. There is a problem. As a technique for avoiding this problem, there is a method of tracking the sun by changing the prism position in accordance with the movement of the sun. However, since this method needs to give mobility to the solar cell unit itself, not only the structure of the solar cell is complicated, but also there is a problem that driving energy for tracking is required. Therefore, there is a problem that the overall conversion efficiency of the solar cell including this driving energy is substantially lowered.

  This invention is made in order to solve the said problem, The objective is to provide the solar cell which can condense sunlight efficiently to a photoelectric conversion part, and its manufacturing method.

According to this invention,
According to this invention,
A core having a first refractive index;
Directional luminescent particles dispersed in the core that converts light from the outside into guided light,
In a light guide comprising a clad having a second refractive index, which has a core and an interface, and the guided light beam satisfies a total reflection condition at the interface,
The photoelectric conversion unit is provided at an end of the light guide, and the directional light-emitting particles are arranged so that the guided light beam has directivity in the photoelectric conversion unit direction,
A solar cell is provided.

Moreover, according to this invention,
A portion having a first refractive index;
Directional luminescent particles dispersed in the site for converting light from the outside into guided light, and
A core having an interface with the core and having a second refractive index determined so that the guided light beam satisfies a total reflection condition at the interface;
In the light guide made of a clad having a third refractive index that has the interface with the part or the core and the guided light beam satisfies the total reflection condition at the interface,
The photoelectric conversion unit is provided at an end of the light guide, and the directional light-emitting particles are arranged so that the guided light beam has directivity in the photoelectric conversion unit direction,
A solar cell is provided.

Furthermore, according to the present invention,
A first light guide and a second light guide, wherein the first and second light guides are:
A core having a first refractive index;
Directional luminescent particles dispersed in the core that converts light from the outside into a guided light,
A structure comprising a clad having a core and an interface and having a second refractive index determined so that the guided light beam satisfies a total reflection condition at the interface; or
A portion having a first refractive index;
Directional luminescent particles dispersed in the site for converting light from the outside into guided light, and
A core having an interface with the core and having a second refractive index determined so that the guided light beam satisfies a total reflection condition at the interface;
The second light guide has a structure including a clad having a third refractive index that has an interface with the portion or the core and the guided light beam satisfies a total reflection condition at the interface. A body is disposed at an end of the first light guide, and has a photoelectric conversion unit at the end of the second light guide;
The directional luminescent particles dispersed in the first light guide are arranged so that the light beam guided in the first light guide has directivity in the second light guide direction,
The directional luminescent particles dispersed in the second light guide are arranged so that the light beam guided in the second light guide has directivity in the photoelectric conversion unit direction. A solar cell is provided.

Furthermore, according to the present invention,
In the directional light emitting particle in the light guide described above, a solar cell is provided in which the guided light beam has a wavelength different from that of the external light beam.

In addition, according to the present invention,
In the above-described solar cell, there is provided a method for manufacturing a solar cell, wherein the directivity of the guided light beam uses orientation of directional light-emitting particles resulting from a stretching process when forming the light guide. .

  According to the solar cell of the present invention, unlike the conventional solar cell using light guiding and condensing action, the manufacturing method is relatively easy, the energy consumption during the manufacturing is small, and the sun incident on the light guide plate The light beam can be efficiently guided to the locally arranged photoelectric conversion elements. Further, it is possible to collect light in the central wavelength region adapted to the photoelectric conversion element by utilizing the wavelength conversion characteristics of the light emitting element. In addition, since the locally disposed photoelectric conversion element itself can also have a small area, a photoelectric conversion element made of a single crystal substrate having excellent photoelectric conversion characteristics can be used.

1 is a perspective view schematically showing a solar cell according to a first embodiment of the present invention. FIG. 2 is a perspective view schematically showing a flat light guide member shown in FIG. 1. It is sectional drawing which shows schematically the flat light guide member shown by FIG. FIG. 2 is a perspective view schematically showing luminescent fine particles dispersed in a core of a flat light guide member shown in FIG. 1. It is sectional drawing which shows roughly the process in which the flat light guide member shown by FIG. 1 is manufactured. It is sectional drawing which shows roughly the light ray locus | trajectory in the flat light guide member shown by FIG. (A), (b) and (c) is typical sectional drawing which shows more specifically the process of manufacturing the flat light guide member shown by FIG. It is a perspective view which shows roughly the solar cell which concerns on 2nd Embodiment of this invention. (A) And (b) is the longitudinal cross-sectional view which cut | disconnects the fiber-shaped light guide member shown by FIG. 8 along the extension direction of a light guide member, and the extension direction of a light guide member. It is the longitudinal cross-sectional view shown roughly cut | disconnected in the orthogonal plane. It is a schematic cross section which shows roughly the apparatus which manufactures the fiber-shaped light guide member shown in FIG. (A) And (b) is sectional drawing which shows roughly the light ray locus | trajectory in the light guide member shown by FIG. It is sectional drawing which shows roughly the light guide structure which arranged the fiber-shaped light guide member shown in FIG. 8 in parallel. It is a perspective view which shows roughly the modification of the fiber-shaped light guide member shown in FIG. (A) And (b) is the longitudinal cross-sectional view which cut | disconnects the fiber-shaped light guide member shown by FIG. 13 along the extension direction of a light guide member, and the extension direction of a light guide member. It is the longitudinal cross-sectional view shown roughly cut | disconnected in the orthogonal plane. It is a top view which shows roughly the light guide structure provided with the structure where the some fiber-shaped linear light guide member shown in FIG. 8 is curved and arrange | positioned. It is a top view which shows roughly the modification of the light guide structure shown in FIG. It is sectional drawing which shows schematically the light guide member of the solar cell which concerns on 3rd Embodiment of this invention. (A) And (b) is the longitudinal cross-sectional view which cut | disconnects the fiber-shaped light guide member shown by FIG. 17 along the extension direction of a light guide member, and the extension direction of a light guide member. It is the longitudinal cross-sectional view shown roughly cut | disconnected in the orthogonal plane. (A) And (b) is sectional drawing which shows roughly the light ray locus | trajectory in the light guide member shown by FIG. It is sectional drawing which shows schematically the light guide member of the solar cell which concerns on 4th Embodiment of this invention. FIG. 21 is a perspective view schematically showing a flat light guide member shown in FIG. 20.

  Hereinafter, a solar cell according to an embodiment of the present invention will be described with reference to the drawings as necessary.

  FIG. 1 is a perspective view schematically showing a solar cell according to the first embodiment of the present invention. As shown in FIG. 1, the solar cell includes a photoelectric conversion element (photoelectric conversion cell) 28 that converts incident light into electric power Pw and outputs the electric power Pw, and the photoelectric conversion element 28 is one of the flat light guide members 30. It is arranged and fixed on the side end face. A light reflecting electrode (light reflecting layer) 27 is provided on the other side end surface facing the one side end surface of the light guide member 30. The flat light guide member 30 includes a light incident surface 30A directed to the sunlight 12, and a core layer 24 in which a large number of light-emitting fine particles 26 are dispersed substantially uniformly as shown in FIGS. A structure sandwiched between the layers 22-1 and 22-2 is formed. Here, the light-emitting fine particles 26 are extremely small particles compared to the thickness sandwiched between the clad layers of the core layer, and are referred to as fine particles from this viewpoint. Further, the core layer 24 and the clad layer 22 are totally reflected at the interface between the core layer 24 and the clad layers 22-1 and 22-2 in the same manner as the core and clad of a normal optical fiber. As described above, the refractive indexes of the core layer 24 and the cladding layers 22-1 and 22-2 are set. In addition, the light guide member 30, particularly the clad layer 22-1 on the incident surface 30 </ b> A side, has sufficient light transmittance so that the external light beam 12 can enter the core layer 24.

  The light emitting fine particles 26 are particles capable of emitting light incident from the outside with directivity as schematically shown in FIG. Hereinafter, this is referred to as directional luminescent particles. Here, the necessary condition of the luminescent particles is to give directivity to the light beam, and the directional luminescent particles can also perform wavelength conversion together with the directional light emission. In the wavelength conversion, for example, the wavelength of incident light is converted by photoluminescence (PL) emission to emit light 14 having a wavelength different from that of the incident light, and directivity is given to the light as shown in FIG. It is a substantially cylindrical particle that directs light rays from its end faces 26A, 26B to the outside. For example, in the wavelength conversion, when the light emitting fine particles 26 can emit light 14 having a central wavelength region of 650 nm, the light rays 12 having a shorter wavelength are converted into light rays 14 near 650 nm by the light emitting fine particles 26. Case corresponds. Further, as the light emitting fine particles 26 that emit light by photoluminescence (PL), for example, there is lead sulfide (PbS) produced by controlling the fine particle diameter to several nanometers. In the light emitting fine particles 26 of this lead sulfide (PbS), It is possible to absorb the light 12 on the short wavelength side, convert it to a light 14 having a wavelength near 880 nm, and emit it. The light-emitting fine particles 26 are said to have excellent conversion efficiency at wavelengths having energy in the vicinity of 1.4 eV. Since sunlight has a continuous spectral distribution from the ultraviolet region to the long wavelength side, for example, when a wavelength of about 880 nm is applicable as a wavelength having energy near 1.4 eV, The light beam 12 from the ultraviolet region to 880 nm is subjected to light wavelength conversion and direction control using a light emitting element (fine particles capable of controlling wavelength conversion and light direction) 26, and directed to the photoelectric conversion element 28. The photoelectric conversion element 28 is introduced with a uniform light beam 14 having excellent conversion efficiency.

  The orientation direction of the light emitting fine particles 26 is aligned by an extending process as indicated by an arrow Ex in FIG. 5 so that the directivity of the light emitting fine particles 26 is totally reflected at the interface between the core layer 24 and the cladding layers 22-1 and 22-2. It can be set in the direction that satisfies the condition. That is, as shown in the left region of FIG. 5, the directivity of the luminescent particles is not uniform. On the other hand, in the light emitting fine particles 26, the clad members 22-1, 22-2 and the core layer 24 are pulled in the stretching process as shown in FIG. When extending, as shown in FIG. 5, the orientation direction (long axis direction) of the light emitting fine particles 26 is aligned with the extending direction, and the end faces 26A and 26B of the light emitting fine particles 26 are arranged on one side and the other side of the flat light guide member 30. Oriented to face the end face. In the light guide member 30 thus stretched, the light rays from the light-emitting fine particles 26 are repeatedly totally reflected at the interface between the core layer 24 and the cladding layers 22-1 and 22-2 in the same manner as the light rays in the optical fiber. However, the light is guided through the core layer 24 and introduced into the photoelectric conversion fine particles 26.

  In the solar cell shown in FIG. 1, when the solar rays 12 are arranged so as to irradiate the light incident surface 30 </ b> A, the external light rays 12 irradiated on the light incident surface 30 </ b> A are within the plate-shaped light guide member 30. As shown in FIG. 6, the light is incident on the luminescent particles 26, the wavelength is converted by the directional luminescent particles 26, and the converted light beam is emitted from the end face of the directional luminescent particles 26. The emitted light is guided through the core layer 24 while repeating total reflection at the interface between the core layer 24 and the clad layer 22, and one side of the plate-shaped light guide member 30 along the light incident surface 30 </ b> A. The light is guided to a photoelectric conversion element (photoelectric conversion cell) 28 provided on the end face. In addition, the light beam directed to the other side end surface of the plate-shaped light guide member 30 is reflected by the light reflecting electrode (light reflection layer) 27 and provided on one side end surface of the plate-shaped light guide member 30. The light is guided to an element (photoelectric conversion cell) 28. In the photoelectric conversion element 28, the incident light beam is converted into electric power and output as electric power Pw to a load (not shown).

  As described above, in the solar cell according to the first embodiment of the present invention, unlike the conventional solar cell using light guiding and condensing action, the manufacturing method is relatively easy and the energy consumption during manufacturing is In addition, it is possible to efficiently guide sunlight incident on the light guide plate to the photoelectric conversion elements 28 disposed locally. Further, it is possible to collect light in the central wavelength region adapted to the photoelectric conversion element by utilizing the wavelength conversion characteristics of the light emitting element. In addition, since the locally disposed photoelectric conversion element itself can also have a small area, a photoelectric conversion element made of a single crystal substrate having excellent photoelectric conversion characteristics can be used.

  More specifically, the light guide (member 30) is manufactured by being stretched through the steps shown in FIGS. First, as shown in FIG. 7A, luminescent fine particles 26 capable of directional light emission are prepared. At this time, the orientation of the oriented luminescent particles is disordered. It is dispersed and mixed in a plate-like core member 34 having a thickness larger than that of the core layer 24. Next, clad members 32-1 and 32-2 to be the clad layer 22 are formed on both surfaces of the plate-like core member 34. The clad members 32-1 and 32-2 are also formed to have a larger thickness than the clad layer 22 to be manufactured in the same manner. Therefore, as shown in FIG. 7B, the plate-like core member 34 is covered with the plate-like clad members 32-1 and 32-2, and is larger than the plate-like light guide member 30 to be manufactured. A plate-like structure having a thickness is prepared. Here, for example, an acrylic resin can be used as the core material, and a fluorine-based resin can be used as the cladding material. The plate-like structure is heated between the rolling rollers 37 and 39 as shown in FIG. 7C in a state where the plate-like structure is heated so as to be equal to or higher than the softening points of the core layer 24 and the cladding layers 22-1 and 22-2. It is guided and rolled by the rolling rollers 37 and 39 under a heated state. In this rolling process, the core layer 24 is stretched, and the luminous particles 26 that are initially arranged in the non-oriented state are rearranged by stretching, and the orientation direction (major axis direction) of the luminous particles 26 is aligned with the stretching direction. The end surfaces 26A and 26B of the light emitting fine particles 26 are oriented so as to be directed to one side and the other side end surface of the flat light guide member 30. Moreover, a desired plate thickness is given to the plate-shaped light guide member 30 by adjusting the pitch between the rolls 40 and 42 during rolling.

  In the solar cell shown in FIG. 1, the reflective electrode 27 is provided on one of the opposing end faces of the plate-shaped light guide member 30, and the photoelectric conversion element 28 is attached to the opposite side. This is because the luminous fine particles 26 are not only oriented in the direction orthogonal to the plate thickness direction (for example, the longitudinal direction) by the rolling process at the time of manufacturing shown in FIG. The orientation of the light beam emitted from the end face of the photoelectric conversion element 28 is specified by the stretching in the in-plane direction. Accordingly, when the arrow Ex in FIG. 7C is set in the rolling direction, the luminescent fine particles 26 are easily oriented in the direction of the arrow Ex also in the in-plane direction, and thus the light beam is directed toward the end face perpendicular to the arrow Ex. Is propagated. Here, the external light beam 12 incident on the plate-shaped light guide member 30 is secondarily wavelength-converted in the core layer 24 by the directional light-emitting fine particles 26 dispersed in the core layer 24, so that the inside of the core layer 24. The light is guided as a wavelength-converted light beam in the propagation direction. Since the core layer 24 is sandwiched by the clad layer 22, the light beam directed to the clad layer 22 is totally reflected at the interface between the core layer 24 and the clad layer 22, and repeats the total reflection, so that the plate shape Light is guided toward the end surface of the light guide member 30. In other words, the external light beam 12 irradiated on the surface of the plate-shaped light guide member 30 undergoes wavelength conversion and propagates toward the end surface of the light guide member 30. The photoelectric conversion element 28 that is optimal for photoelectric conversion of the propagated light beam wavelength is disposed on the end face, so that the wavelength converted and propagated light beam is photoelectrically converted into a current. In such a solar cell structure, the area of the light irradiation surface (incident surface) of the photoelectric conversion element 28 can be made sufficiently smaller than the area of the surface of the plate-shaped light guide plate 20 to which the external light beam 12 is irradiated. As a result, as the structure of the solar cell, a load in the manufacturing process can be suppressed, and a solar cell module having a large area incident surface can be manufactured.

  In addition, in 1st Embodiment, although the shape of the plate-shaped light guide member 30 is made into a rectangular parallelepiped, it is not limited to this shape, You may form in another shape. Moreover, although the photoelectric conversion element 28 is provided in one of the four end surfaces of a rectangular parallelepiped, it is not limited to this.

  8 and 9 (a) and 9 (b) show a light guide member 40 of a solar cell according to the second embodiment of the present invention. In the second embodiment shown in FIG. 8 and FIGS. 9A and 9B, unlike the first embodiment shown in FIGS. 1 to 7, a flat light guide member 30 is used. Instead, a fiber-shaped light guide member 40 is employed.

  The fiber-shaped light guide member 40 shown in FIG. 8 and FIGS. 9A and 9B includes a core 42 and a clad 44 covering the core 42 in the same manner as a normal optical fiber. In the core 42, as in the core 24, luminous particles 26 that can emit light having directivity are dispersed. The luminescent fine particles 26 are the same as the fine particles shown in FIG. 4, so refer to the description in the first embodiment. Further, the core 42 and the clad 44 have a refractive index that satisfies the condition that the light beam propagating in the core 42 is totally reflected at the interface between the core 42 and the clad 44 as in the case of a normal optical fiber. Is given. In other words, the refractive index of the core 42 is set higher than that of the clad 44 so that the light beam 14 can be guided.

  The fiber-shaped light guide member 40 is irradiated with light from the outside in the same manner as shown in FIG. 6 and is incident on the core 42 through the cladding 44 having excellent transparency in the main wavelength region of the external light. In the core 42, the incident light beam enters the light emitting fine particle 26 as schematically shown in FIG. 4 in a cylindrical shape, and the light beam converted by the wavelength conversion in the light emitting fine particle 26 is converted into the end faces 26A, 26A of the light emitting fine particle 26. From 26B. Here, since the long axes of the luminescent fine particles 26 are arranged substantially along the extending direction of the core 42, the light emitted from the end faces 26 A and 26 B of the luminescent fine particles 26 is at the interface between the core 42 and the clad 44. The total reflection is repeated and propagated through the core 42.

  The fiber-shaped light guide member 40 shown in FIG. 8 is manufactured through the manufacturing method shown in FIG. 10 and the luminescent particles 26 are oriented in the core 42 so that directional light emission is possible. That is, first, a columnar member 50 is prepared in which the luminous particles 26 are dispersed non-oriented in the core 42 and the outer periphery of the core 42 is covered with the clad 44. The columnar member 50 is heated and softened in the heating furnace 52 and guided to the capstan 54. The heat-softened columnar member 50 is stretched by being pulled by a take-up drum 56 in a capstan 54, given a desired size (diameter), and formed into a fiber-shaped light guide member 40. The fiber-shaped light guide member 40 formed by the capstan 54 is wound around a winding drum 56.

  Since the core 42 is stretched in the molding process described above, the non-orientated luminescent particles 26 are rearranged by stretching and oriented along the longitudinal direction (fiber extending direction). As a result, the end faces 26A and 26B of the respective light emitting fine particles 26 are directed in the extending direction of the core 42, and the wavelength-converted light beam 14 is completely transmitted from the end faces 26A and 26B of the light emitting fine particles 26 at the interface between the core 42 and the clad 44. Directed to be reflected.

  11 (a) and 11 (b), for example, the paths of the light beams 12 and 14 when the external light beam 12 such as sunlight is incident on the fiber-shaped light guide member 40 as shown in FIG. Is schematically shown. As already described, when the external light beam 12 is incident on the fiber-shaped light guide member 40, the wavelength of the incident light beam 12 is converted by, for example, photoluminescence in the light emitting fine particles 26 that are oriented and dispersed in the core 42. It is converted into a light beam 14 having directivity. This wavelength conversion means that, for example, when the luminescent fine particles 26 can emit light having a central wavelength region of 650 nm, light having a shorter wavelength is converted into a light beam 14 near 650 nm. Further, since the directivity of the light emitting fine particles 26 is emitted in the total reflection direction in the core 42 in FIG. 11A by the stretching process, the light rays 14 from the light emitting fine particles 26 are the same as the light rays in the optical fiber. The inside of the core 42 is guided while repeating total reflection at the interface between the core 42 and the clad 44.

  As shown in FIG. 11B, since the fiber-shaped light guide member 40 has a circular cross-sectional shape, for example, the light ray 14 incident so as to be orthogonal to the extending direction of the light guide member 40 is the cladding 44. Acts as a lens and can be condensed in the core 42. Therefore, the outside light 12 is concentrated and directed to the light emitting fine particles 26, and the light conversion efficiency in the light emitting fine particles 26 can be increased.

  As shown in FIG. 12, in the structure in which the fiber-shaped light guide members 40-1 to 40-n are arranged in parallel, the external light 12 can be received over a wider area. That is, even if it is the fiber-shaped light guide member 40, the surface-expanded light guide member 40 can be realized with an integrated structure arranged in parallel. In this structure, the adjacent clad 44 is a region that does not contribute to the wave guide of the light beam 14, but it is also possible to collect the external light beam 12 on the core 42 by the lens action (condensing action) of the clad 44 itself. It is.

  In order to further improve the lens action (condensing characteristics) of the external light beam 12, the external light beam 12 is applied to the core 42 on the outer periphery of the clad 44 as shown in FIGS. 13 and 14A and 14B. A refractive index control layer 48 for condensing light may be provided. The refractive index control layer 48 refracts the external light 12 toward the core 42, and further refracts the refracted light beam toward the core 42 by the clad 44, and the external light beam 12 incident on the light guide member 40. Most of them may be guided to the core layer 42. In this structure, in the structure in which the outer periphery of the core 42 is covered with the clad 44, the refractive index of the core 42 and the clad 44 is limited in order to totally reflect the light beam 14 at the interface between the core 42 and the clad 44, so that sufficient condensing is possible. Although there is a possibility that the action cannot be given, the refractive index control layer 48 provided on the outer periphery of the clad 44 may give a sufficient lens action (light condensing action) to the refractive index control layer 48 although there is a limitation on the refractive index. it can. Therefore, according to the structure shown in FIG. 13 and FIGS. 14A and 14B, a more efficient solar cell can be provided.

  Not only the case where a plurality of linear light guide members 40 are arranged in parallel, but one long light guide member 40 is curved and unfolded in a plan view as shown in FIGS. You may arrange | position so that it may have the light incident surface of an area. A reflective surface 27 may be provided on the light exit surface at one end of the light guide member 40, and a photoelectric conversion element 28 may be provided on the light exit surface at the other end. In the structure shown in FIGS. 13 and 14A and 14B, since the fiber-shaped light guide member 40 is continuously developed in a plane, this structure provides a large-area solar cell. can do. Further, in this structure, the fiber-shaped light guide member 40 has a light guide function and a light collecting function, and the photoelectric conversion element 28 receives light having a sufficiently small area compared to the area irradiated with the external light beam 12. The photoelectric conversion element 28 in which a photoelectric conversion part is formed on a single crystal substrate that has an excellent photoelectric conversion characteristic can be used. For example, in a solar cell in which a compound semiconductor composed of Group 3 and Group 5 elements is formed on a gallium arsenide substrate, a higher conversion efficiency can be realized as compared with a structure composed of Si. Therefore, a high-efficiency solar cell having excellent photoelectric conversion efficiency can be provided.

  In addition, as shown in FIG. 16, the light emitting surface at the other end of the fiber-shaped light guide member 40 and the light receiving portion of the photoelectric conversion element 28 are optically connected by an optical fiber 49 having excellent optical waveguide characteristics. The light beam 14 may be guided from the light guide member 40 to the photoelectric conversion element 28 via the optical fiber 49. According to the solar cell shown in FIG. 16, the photoelectric conversion element 28 can be installed relatively freely, and the degree of freedom of installation of the solar cell can be increased. As an example, a solar cell is generally installed on the roof of a house or a building. However, such an external environment has a large change in outside air temperature or a change in humidity, and is not preferable for the photoelectric conversion element 28. Yes. However, according to the structure shown in FIG. 16, the photoelectric conversion element 28 can be installed in a temperature-controlled dark room or the like without placing it in a harsh external environment, and a reduction in photoelectric conversion efficiency can be prevented. In addition, the photoelectric conversion element 28 can be prevented from being deteriorated in the external environment. Furthermore, the power Pw taken out from the photoelectric conversion element 28 by photoelectric conversion can be supplied to the load with a relatively short wiring length, and power loss in the wiring can be reduced.

  FIGS. 17-19 has shown the light guide member 60 and the waveguide light of the solar cell which concerns on the 3rd Embodiment of this invention. In the solar cell according to the third embodiment, the light guide member 60 is formed in a fiber shape as in the second embodiment, but not in the core 42 unlike the second embodiment. In the second clad 62, the light emitting fine particles 26 are given a light emitting property of light emission along the extending direction of the light guide member 60 and are dispersed substantially uniformly. That is, the light guide member 60 shown in FIG. 17 and FIGS. 18A and 18B includes first and second clads 44 and 62, and the fiber-like second clad 62 is covered by the core 42. The core 42 is further covered with a first cladding 44. In the second clad 62, the light-emitting fine particles 26 capable of emitting light having a directivity are uniformly dispersed so as to be oriented in the extending direction of the second clad 62. Here, the luminescent fine particles 26 emit light having a directivity similar to the fine particles shown in FIG. 4, for example, the directional light 14 by converting the wavelength of the external light 12 incident by photoluminescence. In addition, the core 42 and the first and second claddings 44 and 62 have a light beam propagating through the core 42 in the same manner as a normal optical fiber. A refractive index that satisfies the total reflection condition is given at the interface and the interface between the core 42 and the second cladding 62. That is, the core 42 is set to have a higher refractive index than the first clad 44 and the second clad 62 so that the light beam 14 can be guided.

  As shown in FIGS. 19A and 19B, the fiber-shaped light guide member 60 is irradiated with light from the outside, and the inside of the second cladding 62 passes through the transparent first cladding 44 and the core 42. Is incident on. In the second clad 62, incident light enters the light emitting fine particles 26, and light rays 14 having directivity in the longitudinal direction of the fiber are emitted from the end faces 26 A and 26 B of the light emitting fine particles 26. Here, the light beam 14 may be converted to a different wavelength with respect to the light beam 12. It is. The emitted light beam 14 propagates through the second cladding 62 and enters the core 42. Here, since the long axes of the light-emitting fine particles 26 are arranged substantially along the extending direction of the core 42, the light-emitting fine particles 26 are emitted from the end surfaces 26 A and 26 B of the light-emitting fine particles 26 schematically shown in FIG. The light beam that has entered and propagated is totally reflected at the interface between the core and the first cladding and at the interface between the core and the second cladding, and is guided in the core.

  In the structure shown in FIGS. 17 and 18 (a) and (b), unlike the first or second embodiment, the luminous particles 26 are not dispersed in the core 42 that propagates the light beam. The propagation of the light beam 14 is efficiently guided in the core 42 without being inhibited by the light emitting fine particles 26.

  In the solar cell according to the third embodiment, the fiber-shaped light guide member 60 is described as in the second embodiment, but can be applied to the same form as in the first embodiment. That is, assuming that FIG. 2 shows a cross section of the flat light guide member shown in FIG. 17, the flat second clad 62 has two flat cores so as to have the form shown in FIG. The first clad 44 may be formed on the two flat cores 42 so as to be sandwiched between the two flat plates 42. In the solar cell having such a structure, as shown in FIGS. 19A and 19B, the wavelength of the external light 12 is converted by the luminescent fine particles 26, and the external light 14 is converted from the luminescent fine particles to the two flat cores 42. It is introduced and propagated through the two flat cores 42.

  FIG. 20 shows a solar cell according to the fourth embodiment of the present invention. The solar cell shown in FIG. 20 includes a flat light guide member 70 having the same structure as the flat light guide member 30 shown in FIG. 2, and the flat light guide members 70 are opposed to each other. The side surfaces of fiber light guide members 72-1 and 72-2 having the same structure as the light guide members 40 and 60 shown in FIG. 8, FIG. 13 or FIG. ing. Photoelectric conversion elements 28-1 and 28-2 are provided at one end in the extending direction of the fiber light guide members 72-1 and 72-2, and a reflective layer (see FIG. (Not shown) or a photoelectric conversion element (not shown) is provided. The light beam guided in the fiber-shaped light guide members 72-1 and 72-2 is reflected by the reflection layer and directed to the photoelectric conversion elements 28-1 and 28-2, and the photoelectric conversion elements 28-1 and 28-. 2 is received, converted into electric power and output. The light beams guided in the fiber-shaped light guide members 72-1 and 72-2 are photoelectric conversion elements 28-1 and 28-2 provided at both ends of the light guide members 72-1 and 72-2, and illustrated. The light is received by the photoelectric conversion element that is not converted into electric power Pw1, Pw2, and output.

  As shown in FIGS. 2 and 3, the flat light guide member 70 has a structure in which the core 24 is sandwiched between the clads 22-1 and 22-2. As shown in FIG. 4, the particles are uniformly dispersed so as to be oriented along the Z direction. In the planar light guide member 70 having this structure, the light beam 12 incident from the outside, for example, the light beam 12 incident along the Y direction, is emitted from the end faces 26A and 26B of the light emitting element 26 in the Z direction by the light emitting element 26. Emitted as a light beam 14. The light beam 14 is guided while satisfying the total reflection condition at the interface between the core and the clad, and is directed to the opposite end surfaces of the light guide member 70, and is introduced into the fiber-shaped light guide members 72-1 and 72-2. Is done.

  For example, when the structure shown in FIG. 8 (or FIG. 13 or FIG. 17) is adopted in the fiber light guide members 72-1 and 72-2, the outermost cladding 44 or the cladding 44 and the refractive index control layer 48 are used. Since the combination of the above has a condensing function (lens function), the incident light beam 14 enters the core 42 as shown in FIGS. 9A and 9B or FIGS. 19A and 19B. The dispersed light emitting elements 26 or the light emitting elements 26 dispersed in the clad 62 as shown in FIG. This light beam is given directivity by the light emitting element 26 in the core 42 or the light emitting element 26 in the clad 62, and directivity is given in the longitudinal direction of the fiber light guide members 72-1, 72-2. Is guided through the core 42. The light beams guided through the cores 24 and 44 are reflected at one end of the fiber light guide members 72-1 and 72-2, respectively, and the photoelectric conversion elements 28-1 and 28-2 provided at the one end. Is converted into electric power Pw1 and Pw2.

  In the flat waveguide member 70 as shown in FIG. 21, the reflection layer 74 is provided on the surface facing the light incident surface, and the light beam 12 that has passed through the waveguide member 70 is again transmitted. The light may be reflected by the reflective layer 74 toward the inside of the waveguide member 70 and the light emitting element 26 may be irradiated with the reflected light. By providing the reflective layer 74, for example, an external ray such as sunlight can be directed to the light emitting element 26, and some components that are transmitted without being absorbed by the particles are included in the layer containing the particles again. The light conversion efficiency can be further improved.

  According to the solar cell shown in FIG. 20, since the photoelectric conversion element 28 may be installed at the fiber end, the photoelectric conversion element 28 is much smaller than the solar cell according to the first embodiment. An element having a light receiving portion with a large area can be obtained.

  In the solar cell shown in FIG. 20, the light guide wavelength in the plate-shaped light guide member 70 and the light guide wavelength in the fiber-shaped light guide need not be the same. As an example, when the photoelectric conversion element 28 having excellent photoelectric conversion characteristics in the wavelength region of 670 nm is used, the directional light-emitting fine particles 26 capable of wavelength conversion in the wavelength region of 670 nm are used in the fiber-shaped light guide member. In the plate-shaped light guide, the luminescent fine particles 26 having directivity capable of wavelength conversion in the wavelength region of 650 nm can also be used.

  In the above-described embodiment, only the structure in which the solar cell is expanded in a plane is described, but FIG. 1, FIG. 15, FIG. 16, and FIG. Alternatively, the solar cells may be arranged so as to be laminated, and wavelength dependence may be given to each solar cell to perform wavelength conversion and photoelectric conversion may be performed by each solar cell.

  There is provided a solar cell that is capable of concentrating sunlight efficiently on a photoelectric conversion element with low cost and low environmental load.

12 . . External light, 14. . . Guided light, 22. . . Clad, 24. . . Core layer, 22-1, 22-2. . . Clad layer, 26. . . Light emitting element, 26A, 26B. . . End face, 27. . . Light reflecting electrode 28, 28-2, 28-2. . . Photoelectric conversion element 30. . . Light guide member, 30A. . . Light incident surface, 32-1, 32-2. . . Clad member, 34. . . Core member, 37, 39. . . Rolling roller, 40, 40-1 to 40-n. . . Light guide member, 42. . . Core, 44. . . Clad, 48. . . Refractive index control layer, 49. . . Optical fiber, 50. . . Columnar member, 52. . . Heating furnace, 54. . . Capstans, 56. . . Winding drum, 60. . . Light guiding member, 62. . . Cladding, 70, 72-1, 72-2. . . Light guide member

Claims (5)

A core having a first refractive index;
Directional luminescent particles dispersed in the core that converts light from the outside into guided light,
In a light guide comprising a clad having a second refractive index, which has a core and an interface, and the guided light beam satisfies a total reflection condition at the interface,
A solar cell comprising a photoelectric conversion unit at an end of the light guide, wherein the directional light emitting particles are arranged so that the guided light beam has directivity in the direction of the photoelectric conversion unit. . A portion having a first refractive index;
Directional luminescent particles dispersed in the site for converting light from the outside into guided light, and
A core having an interface with the core and having a second refractive index determined so that the guided light beam satisfies a total reflection condition at the interface;
In the light guide made of a clad having a third refractive index having the interface with the part or the core, and the guided light beam satisfying the total reflection condition at the interface,
A solar cell comprising a photoelectric conversion unit at an end of the light guide, wherein the directional light-emitting particles are arranged so that the guided light beam has directivity in the direction of the photoelectric conversion unit. . A first light guide and a second light guide, wherein the first and second light guides are:
A core having a first refractive index;
Directional luminescent particles dispersed in the core that converts light from the outside into guided light,
A structure comprising a clad having a core and an interface and having a second refractive index determined so that the guided light beam satisfies a total reflection condition at the interface; or
A portion having a first refractive index;
Directional luminescent particles dispersed in the site for converting light from the outside into guided light, and
A core having an interface with the core and having a second refractive index determined so that the guided light beam satisfies a total reflection condition at the interface;
The second light guide has a structure including a clad having a third refractive index that has an interface with the part or the core and the guided light beam satisfies a total reflection condition at the interface. A body is disposed at an end of the first light guide, and has a photoelectric conversion unit at the end of the second light guide;
The directional luminescent particles dispersed in the first light guide are arranged so that the light beam guided in the first light guide has directivity in the direction of the second light guide,
The directional light-emitting particles dispersed in the second light guide are arranged so that the light beam guided in the second light guide has directivity in the photoelectric conversion unit direction. Solar cell.     4. The solar cell according to claim 1, wherein the guided light beam has a wavelength different from that of the external light beam. 5.   5. The solar cell according to claim 1, wherein the directivity of the guided light beam uses orientation of directional light-emitting particles resulting from a stretching process when forming the light guide. A method for manufacturing a solar cell.

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