JP2009224757A - Photoelectric conversion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric conversion device capable of maintaining sufficient photoelectric conversion efficiency by significantly reducing damage on a light reflective metal layer in forming and manufacturing a light reflecting member, and breakage or the like of the light reflective metal layer when the light reflecting member is formed and stretched. <P>SOLUTION: The photoelectric conversion device includes a conductive substrate 1, a plurality of crystalline semiconductor particles 2 joined on an upper surface of the conductive substrate 1 at intervals between each other, and concave mirror shaped light reflecting members 7 arranged between the crystalline semiconductor particles 2. The light reflecting member 7 includes a concave mirror shaped base 14, a first transparent protection layer 13 formed of resin sequentially formed on a light reflection surface of the base 14, the light reflective metal layer 12, a second transparent protection layer 11 formed of resin, and a surface transparent protection layer 10 formed of resin. The first and second transparent protection layers have softening points lower than that of the surface transparent protection layer 10, and have extension rates at a deformable temperature greater than that of the surface transparent protection layer 10 at the deformable temperature. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a photoelectric conversion device used for photovoltaic power generation and the like, and particularly to a photoelectric conversion device using crystalline semiconductor particles such as crystalline silicon particles.

  A concentrating photoelectric conversion device used as a conventional solar cell cuts a photoelectric conversion element made of a crystalline semiconductor plate such as a crystalline silicon plate to produce a small area photoelectric conversion element, and the photoelectric conversion elements are spaced apart from each other. The thing of the structure which has arrange | positioned the conversion element and provided the condensing lens on each photoelectric conversion element is proposed (for example, refer patent document 1).

  Moreover, as a conventional photoelectric conversion device using crystalline semiconductor particles, an opening is formed in a first aluminum foil, and a silicon sphere having an n-type outer shell on a p-type central core is inserted into the opening. After removing the n-type outer shell on the back side of the sphere, forming an insulating layer on the surface of the silicon sphere from which the first aluminum foil and the n-type outer shell have been removed, and removing the insulating layer on the back side top of the silicon sphere There has been proposed one obtained by joining a silicon sphere and a second aluminum foil via a metal joint (see, for example, Patent Document 2).

  This photoelectric conversion device has a spherical lens for condensing on a silicon sphere. When crystal semiconductor particles are used as in this photoelectric conversion device, gaps are generated between the crystal semiconductor particles, resulting in photoelectric conversion loss, so that light energy incident on the gaps between the crystal semiconductor particles is adjacent to the gaps. A spherical lens is formed on the crystal semiconductor particles in parallel with the curved surface of the surface of the crystal semiconductor particles so that the crystal semiconductor particles are input.

As another conventional photoelectric conversion device, a configuration in which light is reflected by a substrate formed on a concave mirror and condensed on a silicon sphere is known.
JP-A-8-330619 US Pat. No. 5,417,782

  However, the photoelectric conversion device disclosed in Patent Document 1 cuts a crystalline semiconductor plate made of a crystalline silicon plate or the like to produce a small area photoelectric conversion element, and connects the photoelectric conversion elements with a connection tab or the like. Therefore, the number of manufacturing steps is increased, the manufacturing becomes complicated, and the cost cannot be sufficiently reduced.

  In addition, the concave mirror-shaped light reflecting member is mainly composed of a metal such as silver, so that it reacts with sulfur gas, oxygen gas, etc. in the air and deteriorates (blackening in the case of silver) to reflect light. Therefore, it was insufficient to maintain stable photoelectric conversion performance over a long period of time. In addition, the light reflecting member described above is damaged when the metal concave mirror is molded and formed in the process of manufacturing the photoelectric conversion device. It was not big enough.

  Therefore, the present invention has been completed in view of the problems in the above-described conventional technology, and its purpose is to scratch the metal layer (light reflecting layer) when forming and manufacturing the light reflecting member, And it is obtaining the photoelectric conversion apparatus which has a light reflection member which can maintain sufficient photoelectric conversion efficiency by reducing significantly that a damage etc. arise in a metal layer when shape | molding and extending | stretching.

  The photoelectric conversion device of the present invention includes a conductive substrate, a plurality of crystal semiconductor particles bonded to the upper surface of the conductive substrate with a space therebetween, and a concave mirror-shaped light reflecting member disposed between the crystal semiconductor particles. The light reflecting member includes a concave mirror-shaped base, a first transparent protective layer made of resin sequentially formed on the light reflecting surface of the base, a light reflective metal layer, and a second made of resin. A transparent protective layer and a surface transparent protective layer made of a resin, and the first and second transparent protective layers have a softening point lower than that of the surface transparent protective layer and can be deformed. The elongation at temperature is larger than the elongation at the deformable temperature of the surface transparent protective layer.

  According to the photoelectric conversion device of the present invention, the light reflecting member includes the concave mirror-shaped base, the first transparent protective layer made of the resin sequentially formed on the light reflecting surface of the base, the light reflective metal layer, and the resin. A second transparent protective layer and a surface transparent protective layer made of a resin. The first and second transparent protective layers have a softening point lower than the softening point of the surface transparent protective layer and can be deformed. Since the elongation at temperature is larger than the elongation at the deformable temperature of the surface transparent protective layer, it is possible to suppress damage, scratches, etc. occurring in the light reflective metal layer of the light reflecting member during the production of the photoelectric conversion device. Can do.

  In the photoelectric conversion device of the present invention, preferably, the first and second transparent protective layers have a softening point lower than the softening point of the surface transparent protective layer by 60 ° C. or more and an elongation at a deformable temperature of 700. % Or more, the above-described effects are even higher.

  In the photoelectric conversion device of the present invention, preferably, the surface transparent protective layer is made of polyethylene terephthalate, so that it does not flow at a temperature of about 190 ° C. at the time of molding the light reflecting member and maintains a certain thickness so that the molded metal It can protect so that a light-reflective metal layer may not contact a type | mold.

  In the photoelectric conversion device of the present invention, preferably, since at least one of the first and second transparent protective layers is made of an acrylic resin, the first and second transparent protective layers are formed when the light reflecting member is molded. Since the fluidity is higher than that of the surface transparent protective layer, and the elongation rate (stretchability) is higher than that of the surface transparent protective layer, the effect that the fracture portion is not generated is high.

  Moreover, the photoelectric conversion device of the present invention preferably has high light reflectivity because the light reflective metal layer contains at least one of silver and aluminum. Further, since the light-reflective metal layer is protected by being sandwiched between the first and second transparent protective layers, the light-reflective metal layer deteriorates by reacting with sulfide gas, oxygen gas, etc. in the air (silver In this case, it is possible to prevent the light reflectivity from being lowered. Further, peeling of the light reflective metal layer can be prevented. In addition, it is possible to prevent the light-reflecting metal layer from being electrically connected to the light-transmitting conductive layer by the conductive foreign matter and reducing the current collecting property of the light-transmitting conductive layer.

  In the photoelectric conversion device of the present invention, preferably, since the base is made of polycarbonate, it can be easily deformed into a concave mirror shape by a molding die when the light reflecting member is molded.

  In the photoelectric conversion device of the present invention, preferably, since the light reflective metal layer is electrically insulated from the light transmissive conductive layer, an extra amount of light from the light transmissive conductive layer to the light reflective metal layer is obtained. Since there is no electrical continuity, the current is collected sufficiently by the conductive electrode layer that plays the role of a collector electrode, and the current collection effect is improved.

  In the photoelectric conversion device of the present invention, preferably, the light-reflective metal layer has an acute-angled pointed portion at the boundary between the concave mirrors in the longitudinal section. It is possible to suppress the upward reflection of the incident light at the boundary between them, and to efficiently collect the incident light on the crystalline semiconductor particles.

  In the photoelectric conversion device of the present invention, preferably, the surface transparent protective layer has a convex curved surface at the boundary between the concave mirrors in the longitudinal section, so that the surface transparent protective layer is a light-reflective metal layer from the outside. The light-reflective metal layer is formed at an acute angle without being cut at the boundary portion between the concave mirrors.

  The photoelectric conversion device of this embodiment will be described below in detail with reference to the drawings. Note that the following description is merely an example of the embodiment, and the photoelectric conversion device is not limited to the configuration illustrated in FIGS.

  FIG. 1 is a cross-sectional view showing a photoelectric conversion device of this embodiment, FIG. 2 is a cross-sectional view of a light reflecting member in the photoelectric conversion device of this embodiment, and FIG. 3 is a photoelectric conversion of this embodiment. FIG. 4 is a cross-sectional view of a photoelectric conversion module using the photoelectric conversion device of the present embodiment.

  1 to 4, 1 is a conductive substrate, 2 is a crystalline semiconductor particle constituting a granular photoelectric converter, 3 is a semiconductor part (semiconductor layer) constituting a granular photoelectric converter, 4 is an insulating layer, and 5 is a transparent substrate. Photoconductive layer, 6 is a conductive substrate 1, for example, aluminum and crystalline semiconductor particles, for example, an alloy layer of silicon, 7 is a light reflecting member made of transparent resin, 8 is an electrode layer, and 9 is a conductive adhesive layer It is. 10 is a surface transparent protective layer of the light reflecting member 7, 11 is a second transparent protective layer of the light reflecting member 7, 12 is a light reflective metal layer of the light reflecting member 7, and 13 is a first transparent layer of the light reflecting member 7. A protective layer, 14 is a base of the light reflecting member 7, 15 is a surface filling layer, 16 is a surface protective body, 17 is a back surface filling layer, and 18 is a back surface protective layer.

  In the photoelectric conversion device of the present embodiment, the conductive substrate 1 and the second conductive type semiconductor portion 3 are formed on the surface layer, and a plurality of spherical first electrodes are joined to the upper surface of the conductive substrate 1 at intervals. Crystalline semiconductor particles 2 of one conductivity type, an insulating layer 4 formed between the crystalline semiconductor particles 2 on the upper surface of the conductive substrate 1, and translucent conductive material formed on the insulating layer 4 and on the crystalline semiconductor particles 2 A layer 5 and a concave mirror-shaped light reflecting member 7 which is formed on the translucent conductive layer 5 on the insulating layer 4 and focuses the crystalline semiconductor particles 2. The light reflecting member 7 includes a concave mirror-shaped base 14, a first transparent protective layer 13, a light reflective metal layer 12, a second transparent protective layer 11, and a surface sequentially formed on the light reflecting surface of the base 14. The first and second transparent protective layers 13 and 11 have a softening point lower than the softening point of the surface transparent protective layer 10 and have an elongation at a deformable temperature. It is larger than the elongation at the deformable temperature of the surface transparent protective layer 10.

  With the above configuration, it is possible to suppress damage, scratches, and the like that occur in the light reflective metal layer 12 of the light reflecting member 7 when the photoelectric conversion device is manufactured. The light reflecting member 7 is formed by laminating a base 14, a first transparent protective layer 13, a light reflective metal layer 12, a second transparent protective layer 11, and a surface transparent protective layer 10 each of which is first formed into a sheet shape. It is produced by producing a multilayer laminated sheet and molding the multilayer laminated sheet into a concave mirror shape by a mold, but at least one of the first and second transparent protective layers 13 and 11 is partially broken at the time of molding, Due to the influence, wrinkles and the like are generated in the reflective metal layer 12 and the light reflectance can be effectively suppressed from decreasing. Specifically, at the time of molding, the first and second transparent protective layers 13 and 11 are in a state of higher fluidity than the surface transparent protective layer 10, and the elongation (stretchability) is higher than that of the surface transparent protective layer 10. As a result, the fracture portion does not occur. As a result, wrinkles and the like are not generated in the reflective metal layer 12, high light reflectivity is maintained, and the light reflective metal layer can be protected for a long time even after the photoelectric conversion device is manufactured, and sufficient photoelectric conversion is achieved. Efficiency can be maintained.

The softening point described in this embodiment is a temperature at which a substance becomes soft and has a remarkable fluidity. Specifically, it is a temperature at which the viscosity becomes 10 ¹¹ to 10 ¹² P (poise). is there. Moreover, this softening point can be measured with a thermomechanical analyzer, for example. Specifically, the softening point is measured by raising the temperature while the probe is in contact with the sample to be measured and measuring the process in which the probe is buried in the sample.

  The deformable temperature in the present embodiment is a temperature at which the first transparent protective layer 13, the second transparent protective layer 11, and the surface transparent protective layer 10 can be plastically deformed. The transparent protective layer 13, the second transparent protective layer 11, and the surface transparent protective layer 10 have a molding temperature (about 180 ° C. to 240 ° C.) at which the transparent protective layer 13 and the surface transparent protective layer 10 can be molded with a mold or the like.

  Further, the elongation rate is defined by JISK7113 and the like. Specifically, it can be measured by the ratio of the initial length (length before stretching) when the tensile test is performed at the test temperature and the stretched length after the tensile test.

  In the photoelectric conversion device of the present invention, preferably, the first and second transparent protective layers 13 and 11 have a softening point lower than the softening point of the surface transparent protective layer 10 by 60 ° C. and at a deformable temperature. When the elongation is 700% or more, the above-described effects are further enhanced.

  Further, when the light-reflecting metal layer 12 is made of a metal such as silver or aluminum, it is sandwiched and protected by the first and second transparent protective layers 13 and 11, so that the metal is a sulfur gas, oxygen in the air. It is possible to prevent the light reflectivity from being lowered due to deterioration (blackening in the case of silver) by reacting with gas or the like. Moreover, peeling of the light reflective metal layer 12 can be prevented. Further, it is possible to prevent the light-reflecting metal layer 12 from being electrically connected to the light-transmitting conductive layer 5 by the conductive foreign matter and reducing the current collecting property of the light-transmitting conductive layer 5.

  Below, each site | part which comprises the photoelectric conversion apparatus of this Embodiment is demonstrated.

<Conductive substrate>
The conductive substrate 1 may be made of an aluminum substrate, a metal substrate having a melting point equal to or higher than that of aluminum, a ceramic substrate having a conductive layer formed on the surface, and the like. For example, a substrate made of aluminum, aluminum alloy, iron, stainless steel, nickel alloy, alumina ceramic, or the like is used. When the conductive substrate 1 is made of a material other than aluminum, a conductive layer made of aluminum may be formed on the substrate made of a material other than aluminum.

<Crystal semiconductor particles>
The shape of the crystalline semiconductor particle 2 in the present invention is spherical. When the crystalline semiconductor particles 2 are spherical, the crystalline semiconductor particles 2 have a convex curved surface, and the dependency of the incident light on the light beam angle can be reduced. As the spherical shape, a true spherical shape is particularly preferable. In this case, the dependency of the incident light on the ray angle can be made smaller, the bonding property of the crystalline semiconductor particles 2 to the conductive substrate 1 can be improved, and the bonding strength of each crystalline semiconductor particle 2 can be improved. Can be made uniform.

  Further, by making the surface of the crystal semiconductor particles 2 rough, the light reflectance on the surface of the crystal semiconductor particles 2 can be reduced, and the light absorbability of the crystal semiconductor particles 2 can be improved. In order to form this rough surface, the crystalline semiconductor particles 2 may be immersed in an alkaline solution and the surface of the crystalline semiconductor particles 2 may be etched, or the crystalline semiconductor particles 2 may be etched using an RIE (Reactive Ion Etching) apparatus or the like. The surface may be finely processed.

  The particle diameter of the crystalline semiconductor particles 2 is preferably 0.2 to 0.8 mm, and more preferably 0.2 to 0.6 mm in particular for reducing the amount of semiconductor (such as silicon) used. When the particle diameter is less than 0.2 mm, it is difficult to assemble the crystalline semiconductor particles 2 to the conductive substrate 1. Also, if the particle diameter exceeds 0.8 mm, the amount of semiconductor used, including the cutting portion, in the conventional crystalline semiconductor plate type photoelectric conversion device manufactured by cutting out from a crystalline semiconductor mother board (wafer) made of silicon or the like is changed. The merit of using the crystalline semiconductor particles 2 tends to disappear.

  In addition, the particle diameter of the crystalline semiconductor particles 2 is an average particle diameter, which is an average particle diameter before bonding to the conductive substrate 1, and the crystalline semiconductor particles 2 before the formation of the translucent conductive layer 5. The average particle diameter. This average particle diameter can be measured by a particle size distribution measuring device using laser light.

  The crystalline semiconductor particles 2 exhibit the first conductivity type (for example, p-type). In the case of the p-type, a dopant such as B, Al, and Ga is produced, and the crystalline semiconductor particles 2 are produced by a jet method (melting drop method) or the like. It is obtained, for example, by incorporating it into the raw material.

  The crystalline semiconductor particles 2 are made of a single crystal or a polycrystal of a semiconductor, but are particularly preferably single crystals since photocurrent can be taken out efficiently. In the case of polycrystal, recombination of electrons and vacancies occurs at the grain boundary, and as a result, the output of photocurrent decreases.

  The crystalline semiconductor particles 2 are formed into a granular shape by, for example, a melt drop method (jet method) or the like, and single crystallized by a method such as a remelt (remelting) method. Further, depending on the manufacturing conditions, it is possible to obtain crystal semiconductor particles 2 that are substantially single crystallized with few grain boundaries only by the jet method, and may be used as it is in a photoelectric conversion device.

  On the surface layer of the crystalline semiconductor particles 2, a second conductivity type (for example, n-type) semiconductor portion 3 is formed. The second conductivity type semiconductor portion 3 is formed by, for example, a thermal diffusion method, a vapor phase growth method, or the like.

  In the thermal diffusion method, for example, if a semiconductor compound 3 is n-type by inserting a crystalline semiconductor particle 2 into a high-temperature quartz tube for a certain period of time using a phosphorus compound such as phosphorus oxychloride as a diffusing agent, a crystalline semiconductor An n-type semiconductor portion 3 can be formed on the surface of the particle 2. As an example, by inserting the crystalline semiconductor particles 2 into a quartz tube at 900 ° C. for 30 minutes, an n-type semiconductor portion 3 having a thickness of 1 μm can be formed on the surface. However, in this case, as shown in FIG. 1, in order to electrically separate the semiconductor portion 3 and the alloy layer (eutectic layer) 6, the surface of the semiconductor portion 3 except for the vicinity of the alloy layer 6 is covered with an acid resistant resist or the like. It is necessary to remove the semiconductor portion 3 by coating with an etching solution and removing the semiconductor portion 3 of the uncovered portion with an etching solution.

  In the case of the thermal diffusion method, it can be performed before the bonding of the crystalline semiconductor particles 2 and the conductive substrate 1.

  Further, in the vapor phase growth method or the like, for example, the n-type semiconductor portion 3 can be formed by introducing a small amount of a vapor phase of a phosphorus compound serving as an n-type dopant into the gas phase of a silane compound.

  The film quality of the semiconductor part (semiconductor layer) 3 may be any of crystalline, amorphous, or a mixture of crystalline and amorphous, but considering the light transmittance, crystalline or crystalline and amorphous. It is good to mix quality.

The concentration of the trace element in the semiconductor part 3 is preferably about 1 × 10 ¹⁶ to 1 × 10 ²¹ atm / cm ³ , for example. Furthermore, the semiconductor part 3 is preferably formed along a convex curved surface of the surface of the crystalline semiconductor particle 2. By being formed along the surface of the convex curved surface of the crystalline semiconductor particle 2, the area of the pn junction can be increased widely, and carriers generated inside the crystalline semiconductor particle 2 can be efficiently collected. .

<Insulating layer>
The insulating layer 4 formed on the conductive substrate 1 between the crystalline semiconductor particles 2 is made of an insulating material for separating the positive electrode and the negative electrode. That is, the insulating layer 4 is provided so that the translucent conductive layer 5 disposed on the upper surface side thereof does not contact the conductive substrate 1 on the lower surface side. As the insulating material forming the insulating layer 4, to _{SiO 2, B 2 O 3,} Al 2 O 3, CaO, MgO, P 2 O 5, Li 2 O, SnO, ZnO, BaO, and TiO ₂ or the like as optional components Examples thereof include low-temperature firing glass (glass frit) materials made of materials, glass compositions containing fillers made of one or more of the above materials, and organic materials such as polyimide or silicone resin. The amount of the insulating material is not particularly limited, and the light-transmitting conductive layer 5 provided on the insulating layer 4 may be provided uniformly.

  The insulating layer 4 may further contain dispersed insulating particles made of an insulating material such as glass, ceramics, or resin. The average particle diameter of the insulator particles is preferably 4 to 20 μm. When the average particle diameter of the insulator particles is within the range, the insulator particles can be sufficiently dispersed in the insulating layer 4.

<Translucent conductive layer>
The translucent conductive layer 5 is coated on the crystalline semiconductor particles 2 and the insulating layer 4. Here, when the conductive substrate 1 is one electrode, the translucent conductive layer 5 functions as the other electrode.

The translucent conductive layer 5 is made of one or more oxide-based films selected from SnO ₂ , In ₂ O ₃ , ITO, ZnO, TiO _2, etc., and is formed by sputtering, vapor phase growth, or coating. It is formed by a firing method or the like. The translucent conductive layer 5 can also provide an effect as an antireflection film by selecting an appropriate film thickness.

  Since the translucent conductive layer 5 is transparent, a part of incident light is transmitted through the translucent conductive layer 5 in a portion where the crystalline semiconductor particles 2 are not present, and is reflected by the lower conductive substrate 1 to be crystal semiconductor particles 2. The light energy irradiated to the whole photoelectric conversion device can be efficiently guided to the crystal semiconductor particles 2 and irradiated.

  The translucent conductive layer 5 is preferably formed along the surface of the semiconductor portion 3 or the crystalline semiconductor particle 2 and is formed along the convex curved surface of the crystalline semiconductor particle 2. In this case, carriers generated inside the crystalline semiconductor particles 2 can be efficiently collected.

<Light reflecting member>
The light reflecting member 7 has a concave light reflecting metal layer 12 for condensing the crystal semiconductor particles 2. In terms of improving the light collecting property, the light reflective metal layer 12 preferably has a concave mirror structure formed of a partial curved surface such as a spherical surface or a spheroid surface. In particular, it is preferable that the concave curved surface shape is a curved surface shape of an elliptic rotating body in order to reduce the incident angle dependency of light. According to the computer simulation, when the incident angle changes with time like the sun, the curved surface shape of the elliptical rotating body can collect light more efficiently than the curved surface shape of the sphere. Table 1 shows the light use efficiency for the curved surface of the sphere and the curved surface of the spheroid.

  The light-reflective metal layer 12 is preferably formed of a metal layer having a high reflectance such as Ag, Al, Au, Cu, Pt, Zn, Ni, and Cr. And a metal including at least one of Al and Al, or a metal composed of at least one of Ag and Al.

  The light-reflective metal layer 12 has a high reflectivity such as Ag, Al, Au, Cu, Pt, Zn, Ni, and Cr by a method such as vacuum deposition, sputtering, electroless plating, or electrolytic plating. The metal can be thinly formed with a substantially uniform thickness.

  The thickness of the light reflective metal layer 12 is preferably 0.04 to 0.2 μm. By setting this range, the reflectance of the light-reflective metal layer 12 is maintained to prevent the light transmittance from increasing, and the thickness is increased, the surface becomes uneven and the reflected light is scattered. Can be reduced.

  The light reflecting member 7 is placed on the light-transmitting conductive layer 5 between the adjacent crystal semiconductor particles 2 so that the crystal semiconductor particles 2 are exposed from the opening at the lower end portion of the light reflecting member 7 and is directly bonded. Alternatively, as shown in FIG. 4, the light reflecting member 7 is placed on the translucent conductive layer 5, the surface filling layer 15 and the surface protector 16 are sequentially laminated and sealed with a vacuum heating device or the like. , Installed at a predetermined site. Thereby, it is not necessary to perform the operation | work which inserts the crystalline semiconductor particle 2 one by one in the opening part of aluminum foil like the conventional manufacturing method, and the light reflection member 7 can be installed stably at once and easily. it can.

  Further, as shown in FIG. 1, the light reflecting member 7 is preferably formed by integrally forming the electrode layer 8 on the lower surface thereof and then adhering the light reflecting member 7 onto the light-transmitting conductive layer 5 with the conductive adhesive layer 16. The light reflecting member 7 can be further stably and easily installed. The light reflecting member 7 and the electrode layer 8 may not be integrally formed, and the light reflecting member 7 may be fixed on the electrode layer 8 with an adhesive or the like (not shown).

  The light reflecting member 7 is formed of a material such as resin or metal capable of maintaining a concave mirror shape, and an opening is provided at the bottom of the concave mirror shape so that the crystalline semiconductor particles 2 can enter.

  For example, the portion of the light reflecting member 7 excluding the light reflecting metal layer 12 is formed of a resin such as polycarbonate, polyethylene terephthalate, acrylic resin, fluorine resin, olefin resin, or the like. When such a resin is provided, the light-reflective metal layer 12 may be formed by integrally molding the above-described metal foil having a high reflectance on the resin sheet.

  The resin is preferably a resin having flexibility that can be easily deformed by atmospheric pressure. By doing so, the reflection efficiency is improved without the floating of the light reflecting member 7 from the translucent conductive layer 5 spreading to the periphery. Even if the conductive substrate 1, the electrode layer 8, or the insulating layer 4 has irregularities, the light reflecting member 7 is placed on top of them so as to follow it.

  It is preferable that the light reflecting member 7 has a sharp apex at the top (boundary portion between the concave mirrors) in the longitudinal section. Conventionally, when the boundary as shown in Patent Document 3 is wide, a horizontal part is wide at the boundary, and therefore incident light is reflected upward at the boundary. In the present embodiment, since the top of the light reflecting member 7 is an acute-pointed cusp, the upward reflection of the incident light at the top is suppressed, and the incident light is efficiently reflected by the crystalline semiconductor particles 2. Can be condensed. The angle of the acute-angled cusp is about 5 ° to 60 °.

  The light reflecting member 7 made of a resin having a multilayer laminated structure is molded by a molding die having a number of concave mirror-shaped negative shapes (convex shapes) formed of a heat-resistant material such as metal.

<Surface transparent protective layer>
The surface transparent protective layer 10 is coated on the second transparent protective layer 11 to indirectly protect the light reflective metal layer 12. The surface transparent protective layer 10 is a surface of the light-reflective metal layer 12 depending on the surface roughness of the mold, for example, when a resin multilayer laminated sheet that becomes the light-reflecting member 7 having the light-reflective metal layer 12 is formed. It is possible to suppress the occurrence of problems such as damage.

  Further, by protecting the light reflective metal layer 12 from directly contacting the mold with the surface transparent protective layer 10, it is possible to prevent a decrease in the reflectance of the light reflective metal layer 12 in the manufacturing process of the photoelectric conversion device. it can. Furthermore, it can suppress that the malfunction that the light-reflective metal layer 12 deteriorates easily by sulfur gas, oxygen, etc. by using over a long period of time.

  The surface transparent protective layer 10 is made of a resin such as polyethylene terephthalate, polycarbonate, fluororesin, olefin resin, etc., and maintains a certain thickness without flowing when the light reflecting member 7 is molded. The layer 12 is protected from contact. In particular, the surface transparent protective layer 10 is preferably made of polyethylene terephthalate for the above reasons.

  In addition, these resins preferably have a refractive index difference of 0.2 or less, more preferably 0.1 or less, and most preferably no refractive index difference with the surface filling layer 15 (FIG. 4). preferable. By doing so, even if the surface roughness of the molding die is transferred to the surface transparent protective layer 10 to some extent, the optical loss is reduced.

  The thickness of the surface transparent protective layer 10 may be about 1 μm to 50 μm although it depends on the surface roughness of the molding die. By setting the thickness to about 1 μm to 50 μm, the light reflective metal layer 12 is prevented from being scratched by the surface roughness of the molding die, and between the concave mirrors of the light reflective metal layer 12 after molding. It can suppress that a roundness arises in a boundary part (top part), and condensing property falls.

  By providing the surface transparent protective layer 10, the corrosion resistance of the light reflective metal layer 12 can be improved, and higher reliability can be obtained. A separate corrosion resistant coat may be provided between the light reflective metal layer 12 and the surface transparent protective layer 10.

  The light reflective metal layer 12 is preferably electrically insulated from the light transmissive conductive layer 5. By doing so, there is no electrical continuity from the translucent conductive layer 5 to the light-reflective metal layer 12, so that the current is sufficiently collected for the collector electrode such as the electrode layer 8, The current collection effect tends to improve.

  It is preferable that the boundary part (top part) between the concave mirrors of the surface transparent protective layer 10 is comprised from the convex curved surface in the longitudinal cross section, as shown in FIG. Since the top of the surface transparent protective layer 10 is a convex curved surface, the surface transparent protective layer 10 presses the light reflective metal layer 12 from the outside, so that the light reflective metal layer 12 is at the top of the light reflecting member 7. It is formed at an acute angle without being cut. Further, the top of the surface transparent protective layer 10 is formed from a convex curved surface in the vertical cross section, and the top of the light reflecting member 7 is an acute-pointed point in the vertical cross section. Incident light is reflected by the adjacent crystal semiconductor particles 2 without being reflected upward, and a synergistic effect that contributes to the photoelectric conversion effect is obtained.

<First and second transparent protective layers>
The photoelectric conversion device of the present embodiment has a second transparent protective layer 11 between the light reflective metal layer 12 and the surface transparent protective layer 10, and between the light reflective metal layer 12 and the substrate 14. The first transparent protective layer 13 is provided.

  The first transparent protective layer 13 and the second transparent protective layer 11 are formed by compressing and molding the multilayer laminated sheet to be the light reflecting member 7 at the molding temperature at the time of molding. When the protective layer 11 is softened, stress when the surface transparent protective layer 10 is stretched is relieved to protect the light reflective metal layer 12.

  The first and second transparent protective layers 13 and 11 preferably have a softening point that is lower than the softening point of the surface transparent protective layer 10 by 60 ° C. or more and an elongation at a deformable temperature of 700% or more.

  On the other hand, for example, the first transparent protective layer 13 and the second transparent protective layer 11 have a softening point lower than the softening point of the surface transparent protective layer 10 by 60 ° C. or more at a molding temperature (deformable temperature). When the elongation is less than 700%, specifically, the surface transparent protective layer 10 is made of polyethylene terephthalate (about 200% elongation at a softening point of about 250 ° C. and a molding temperature (about 190 ° C.)). When the transparent protective layer 13 and the second transparent protective layer 11 are made of polyester resin (softening point of about 200 to 240 ° C., elongation rate of about 200% at a molding temperature (about 190 ° C.)), the multilayer laminated sheet is compressed. When molding, the stress when the surface transparent protective layer 10 is stretched is easily transmitted to the first transparent protective layer 13, the second transparent protective layer 11, and the light reflective metal layer 12 as it is.

  Therefore, in order to relieve stress when the surface transparent protective layer 10 is stretched, the first and second transparent protective layers 13 and 11 preferably have a softening point of 60 than the softening point of the surface transparent protective layer 10. It is assumed that the elongation at a temperature lower than ° C. and deformable is 700% or more.

  Specifically, for example, when the surface transparent protective layer 10 is made of polyethylene terephthalate (a softening point of about 250 ° C. and an elongation of about 200% at a molding temperature (about 190 ° C.)), the first transparent protective layer 13 and the second transparent protective layer 10 At least one of the transparent protective layer 11 is made of urethane resin (softening point 180 to 190 ° C., elongation rate of about 700% at molding temperature (about 190 ° C.)), acrylic resin (softening point 160 to 180 ° C., molding temperature). (Elongation rate at about 190 ° C. is about 1000%).

  Furthermore, an acrylic resin or the like having a glass transition point (Tg) of 60 to 80 ° C. (a softening point of about 120 to 160 ° C. and an elongation of about 1500% at a molding temperature (about 190 ° C.)) is more preferable.

  Furthermore, both the second transparent protective layer 11 and the first transparent protective layer 13 have a softening point lower than the softening point of the surface transparent protective layer 10 by 60 ° C. or more, and an elongation at a deformable temperature is 700. % Or more is preferable.

  Moreover, the thickness of the 1st transparent protective layer 13 should just be about 1-10 micrometers. By setting the thickness to about 1 to 10 μm, it is possible to obtain sufficient corrosion resistance by covering the light reflective metal layer 12, and also due to the difference in material from the surface transparent protective layer 10, multilayer lamination The sheet can be prevented from being bent and difficult to handle. The first transparent protective layer 13 may be a single layer, but a multiple layer is advantageous for further improving the corrosion resistance.

  The thickness of the second transparent protective layer 11 may be about 0.1 to 1 μm. By setting the thickness to about 0.1 to 1 μm, it is possible to suppress the occurrence of cracks in the light reflective metal layer 12 when the multilayer laminated sheet serving as the light reflecting member 7 is compression-molded, and the decrease in photoelectric conversion efficiency. It is possible to prevent the multilayer laminated sheet from being bent and difficult to handle due to the difference in material from the surface transparent protective layer 10. The second transparent protective layer 11 may be a single layer, but if it is a multilayer, it is advantageous for further improving the corrosion resistance.

  The molding temperature for molding the light reflecting member 7 is preferably a temperature range between the softening point of the surface transparent protective layer 10 and the softening point of the second transparent protective layer 11. In this case, the surface transparent protective layer 10 does not start flowing at the molding temperature, and the second transparent protective layer 11 starts flowing.

  Furthermore, the resin of the second transparent protective layer 11 serving as a light path preferably has a refractive index difference of 0.2 or less with respect to the surface filling layer 15 (FIG. 4), and preferably 0.1 or less. More preferably, there is no difference in refractive index. By doing so, the optical interface is reduced and the optical loss is reduced.

<Substrate>
The light reflecting member 7 includes a base body 14 that is a concave mirror-shaped base body for condensing the crystalline semiconductor particles 2. The base 14 may be made of a material that is easily deformed when formed into a concave shape, and is made of a resin such as polycarbonate or olefin resin.

  The thickness of the base 14 is not particularly limited, but may be any thickness as long as the thickness of the opening for penetrating the crystal semiconductor particles 2 in the light reflecting member 7 after molding is several μm to several tens μm. Since the substrate 14 is located on the back surface side of the light reflective metal layer 12, the color tone is not particularly limited, and may be, for example, transparent or white, and white is considered when slight transmitted light of the light reflective metal layer 12 is taken into consideration. More preferred.

<Electrode layer>
The electrode layer 8 is formed on the conductive adhesive layer 16 on the transparent conductive layer 5 between the adjacent crystalline semiconductor particles 2 in order to reduce the series resistance value between the transparent conductive layer 5 and the external terminal. Is provided as a collector electrode. The electrode layer 8 is used as a low resistance conductor for taking out the photoelectric current generated by the crystalline semiconductor particles 2 from the photoelectric conversion device without causing a resistance loss.

  The electrode layer 8 is preferably made of a metal plate having an opening corresponding to the crystalline semiconductor particle 2, and for example, Al, Cu, Ni, Cr, Ag, and alloys thereof are suitable. The thickness of the electrode layer 8 is preferably 20 to 200 μm. The use of the electrode layer 8 made of a metal plate is preferable in that it also serves as a substrate that firmly supports the light reflecting member 7 formed thereon.

  The conductive adhesive layer 16 is made of an adhesive made of a thermosetting resin or the like containing conductive particles, and electrically connects the electrode layer 8 and the translucent conductive layer 5. It plays the role of fixing. As the conductive particles, Ag, Ni, Au or a composite particle thereof is suitable, and the translucent conductive layer 5 can efficiently collect the generated current with respect to the electrode layer 8. Further, as shown in FIG. 2, the conductive adhesive layer 16 is formed in a circular shape (dot shape) so as to avoid the crystal semiconductor particles 2, and a large number of them are arranged adjacent to the crystal semiconductor particles 2. It is possible to eliminate the formation of a direct shadow area. At the same time, the electrode layer 8 and the conductive adhesive layer 16 can be covered by the light reflecting member 7 described above, and the appearance can be improved. Furthermore, the electrical path of the translucent conductive layer 5 having relatively low conductivity can be shortened by the conductive adhesive layer 16, and the current generated in the crystalline semiconductor particles 2 can be efficiently collected by the electrode layer 8.

<Protective layer>
A protective layer (not shown) may be formed on the translucent conductive layer 5. Such a protective layer preferably has a characteristic of a transparent dielectric, and is formed by, for example, silicon oxide, cesium oxide, aluminum oxide, silicon nitride, titanium oxide, tantalum oxide, yttrium oxide, etc. by CVD or PVD. Are formed on the light-transmitting conductive layer 5 by a single composition or a combination of a single composition or a plurality of compositions.

  Since the protective layer is on the light incident surface side, the protective layer needs to be transparent, and is a dielectric in order to prevent current leakage between the semiconductor portion 3 or the translucent conductive layer 5 and the outside. It is necessary. In addition, if the film thickness of the protective layer is optimized, a function as an antireflection film can be provided.

<Photoelectric conversion module>
Next, a photoelectric conversion module (FIG. 4) is formed using the photoelectric conversion device of this embodiment. The photoelectric conversion module is a module in which a plurality of photoelectric conversion elements are connected in series or in parallel, the generated electrical output is improved, and a practical electrical output can be taken out. The photoelectric conversion module can obtain a sufficient electric output that cannot be obtained by one photoelectric conversion element.

  The surface filling layer 15 on the light reflecting member 7 may be an optically transparent material, and examples of the constituent material include ethylene vinyl acetate polymer (EVA), polyolefin, fluorine-based resin, and silicone resin.

  The surface protector 16 on the surface filling layer 15 is made of an optically transparent and weather-resistant material, and is made of glass, silicone resin, polyvinyl fluoride (PVF), ethylene-4 fluoroethylene copolymer (ETFE), poly Such as tetrafluoroethylene (PTFE), tetrafluoroethylene-perfluoroalkoxy copolymer (PFA), tetrafluoroethylene-6 fluoropropylene copolymer (FEP), polytrifluoroethylene chloride (PCTFE), etc. A fluororesin can be used.

  Moreover, the back surface filling layer 17 can be provided on the back surface of the conductive substrate 1 using the same material as the material of the surface filling layer 15, and a back surface transparent protective layer may be further laminated. As a material for the back surface transparent protective layer, for example, a fluororesin such as polyvinyl fluoride (PVF), ethylene-tetrafluoroethylene copolymer (ETFE), polytrifluoroethylene chloride (PCTFE), polyethylene terephthalate (PET), etc. The resin is good. Examples of the back transparent protective layer include a sheet obtained by laminating an aluminum foil or a metal oxide film using these resins and a metal sheet such as glass or stainless steel.

  In the peripheral portion of the photoelectric conversion device of the present embodiment, the light reflecting member 7 is a spacing member. The spacing member can be easily formed by adding it to the peripheral edge of the mold when the light reflecting member 7 is formed. The interval holding member has a thickness corresponding to the interval between the surface protection body 16 and the insulating layer 4. When the surface protection body 16, the surface filling layer 15 and the photoelectric conversion device are combined and vacuum-heated, photoelectric conversion is performed. The light reflecting member 7 on the apparatus has a role of securing the interval so as not to be destroyed.

  Further, the spacing member may be formed inside the photoelectric conversion device. When the photoelectric conversion device is large, an interval holding member formed inside is effective. At this time, one spacing member may be provided in a region corresponding to one crystalline semiconductor particle, or a plurality of spacing members may be arranged.

  Note that a photoelectric conversion device in which one photoelectric conversion element (a photoelectric conversion unit having one crystal semiconductor particle 2) having the above-described configuration is provided or a plurality of photoelectric conversion elements are connected (connected in series, parallel, or series-parallel) To do. Further, one photoelectric conversion device is provided, or a plurality of devices connected in series (connected in series, parallel, or series-parallel) is used as the power generation means, and the generated power is directly supplied from the power generation means to the DC load. Good. In addition, after the power generation means converts the generated power to appropriate AC power via power conversion means such as an inverter, the generated power can be supplied to an AC load such as a commercial power system or various electric devices. It is good also as a power generator. Furthermore, it is also possible to use such a power generation device as a photovoltaic power generation device such as a solar power generation system in various modes by installing it on the roof or wall surface of a building with good sunlight.

  Next, although the Example of the photoelectric conversion apparatus of this invention is described, this invention is not limited to this Example.

  The photoelectric conversion device of the example was manufactured as shown below.

  First, a large number of p-type crystalline silicon particles having a diameter of about 0.3 mm were used as the crystalline semiconductor particles 2, and a pn junction portion was formed using the outer portion as an n + semiconductor portion by subjecting them to phosphorus thermal diffusion treatment.

  Next, a large number (30,000 particles) of crystalline silicon particles are arranged on the main surface of the conductive substrate made of aluminum at an interval of about 0.6 times the diameter of each other, and both aluminum and silicon are co-located. A large number of crystalline silicon particles were bonded onto the conductive substrate by heating for about 10 minutes at a crystal temperature of 577 ° C. or higher (630 ° C.).

  After the pn separation was performed by etching around the base of the crystalline silicon particles bonded to the conductive substrate, an insulating layer made of polyimide was filled between the many crystalline silicon particles on the conductive substrate. Thereafter, the upper surface of the crystalline silicon particles was washed, and an ITO layer having a thickness of 80 nm was formed as a translucent conductive layer.

  Further, as the electrode layer (collecting electrode), an aluminum foil having a thickness of 50 μm having through holes about the diameter of the crystalline silicon particles is used, and as shown in FIG. 3, surrounded by three crystalline silicon particles on the lower surface of the aluminum foil. Ag paste (Ag particle-containing resin paste) was applied in a circular shape (dot shape) by screen printing. And the electrode layer was formed by heat-processing for 30 minutes at 150 degreeC, pressing on an ITO layer so that a crystalline silicon particle might protrude from the through-hole of an electrode layer.

  Next, the light reflecting member was formed as follows. A light reflecting member was produced by vacuum forming using the following materials using a mold having a width of 1.6 times the diameter of the crystalline silicon particles and a large number of vertically long semi-spheroids arranged.

  On a PET (polyethylene terephthalate, softening point 250 ° C.) film having a thickness of 12 μm as a surface transparent protective layer, a second transparent protective layer made of the material shown in the examples of Table 3 is formed with a thickness of 0.3 μm. A silver layer having a thickness of 100 nm as a light-reflective metal layer is formed on the transparent protective layer by vacuum deposition, and two first transparent protective layers made of the materials shown in the examples in Table 3 are formed on the silver layer by 3 μm. A multilayer laminated sheet formed with a thickness of 1 mm was prepared.

  The multilayer laminated sheet is laminated on a polycarbonate film having a thickness of 50 μm as a substrate, compression-molded into a concave mirror shape with a mold, an opening through which the crystalline semiconductor particles 2 pass is formed at the bottom of the concave mirror shape, and a light reflecting member Was made.

And the light reflection member was arrange | positioned on the translucent conductive layer on an insulating layer so that the crystalline silicon particle as a photoelectric conversion element might each protrude from the opening part of a light reflection member. In addition, a backside protective layer with a thickness of about 0.1 mm formed by laminating a backside filling layer made of EVA (ethylene vinyl acetate) with a thickness of about 0.4 mm, a PET film, a SiO ₂ layer and a PET film on the lower surface of the conductive substrate Layers were laminated. Further, a surface filling layer made of EVA having a thickness of about 0.6 mm and a surface protective body made of glass having a thickness of about 3 mm were sequentially laminated on the upper surface side of the conductive substrate so as to cover the light reflecting member. These were laminated with a vacuum laminator to produce a photoelectric conversion device.

  In addition, the PET film (refractive index: 1.6) as the surface transparent protective layer 10 and the polyester resin (refractive index: 1.6) and urethane resin (refractive index: 1 .. 2) as the second transparent protective layer. 6) The difference in refractive index between the acrylic resin (refractive index: 1.6) and EVA as the surface filling layer 17 (refractive index: 1.5) was 0.1.

(Comparative example)
A photoelectric conversion device of a comparative example was produced as the same configuration as the example except that the materials shown in Comparative Example 1 and Comparative Example 2 of Table 3 were used as the first transparent protective layer and the second transparent protective layer.

  Table 2 shows the results of measuring the reflectance of the light reflecting surface of the concave mirror of the light reflecting member 7 before being incorporated in the photoelectric converting device of the above-described Examples and Comparative Examples. Table 3 shows the results of measuring the photoelectric conversion efficiency of the photoelectric conversion device incorporating the light reflecting member. In Tables 2 and 3, Tg means a glass transition point. Further, the expression “urethane resin / acrylic resin” means that a urethane resin layer and an acrylic resin layer are laminated from the light reflective metal layer 12 side.

  According to Table 2, when the first transparent protective layer and the second transparent protective layer are made of a polyester-based resin (softening point of about 200 to 240 ° C., elongation is about 200% at a molding temperature of 190 ° C., for example), the reflectance is There was only 82%. In the case of a silicone resin (softening point of about 260 ° C., elongation is about 400% at a molding temperature of 190 ° C., for example), the reflectance was only 85.1%. According to microscopic observation with transmitted light, innumerable cracks were generated in the light reflective metal layer.

  When the first transparent protective layer is urethane-based (softening point 180-190 ° C., elongation rate about 700% at a molding temperature of about 190 ° C.) / Acrylic resin, and the second transparent protective layer is polyester-based resin The reflectivity was improved by 5% to 87.3%. According to microscopic observation with transmitted light, the number of cracks generated in the light reflective metal layer was extremely small.

  When the first transparent protective layer and the second transparent protective layer were acrylic resins (softening point: 160 to 180 ° C., elongation rate of about 1000% at a molding temperature of about 190 ° C.), the reflectance was 90.7%.

  In the case where the first transparent protective layer and the second transparent protective layer are low Tg acrylic resins (glass transition point 60 to 80 ° C., softening point 120 to 160 ° C., elongation rate about 190% at a molding temperature 190 ° C.) The reflectance was 93.5%. According to microscopic observation with transmitted light, no cracks in the light-reflecting metal layer were observed.

  From the above, by using a material in which the softening point of at least one of the first transparent protective layer and the second transparent protective layer is 60 ° C. lower than the softening point of the surface transparent protective layer (PET, softening point 250 ° C.), It has been found that there is an effect of suppressing the decrease in reflectivity by reducing or eliminating the damage that occurs in the light reflective metal layer.

  Further, from Table 3, the first transparent protective layer is a urethane resin (softening point 180 to 190 ° C., elongation rate about 700% at a molding temperature of about 190 ° C.) / Acrylic resin, and the second transparent protective layer In Example 1 in which is a polyester resin, the photoelectric conversion efficiency was 11.6%.

  In Example 3 in which the first transparent protective layer and the second transparent protective layer were acrylic resins, the photoelectric conversion efficiency was 12.2%.

  In Example 5 in which the first transparent protective layer and the second transparent protective layer are low Tg acrylic resins, the photoelectric conversion efficiency was 12.8%.

  On the other hand, when the first transparent protective layer and the second transparent protective layer of Comparative Example 1 are polyester resins (softening point of about 200 to 240 ° C., elongation rate of about 200% at a molding temperature of about 190 ° C.), When the conversion efficiency is 11.1% and the first transparent protective layer silicone resin of Comparative Example 2 (softening point is about 260 ° C., elongation rate is about 400% at a molding temperature of about 190 ° C.), The conversion efficiency was 11.4%, and both were lower than in the examples.

  The first transparent protective layer and the second transparent protective layer are materials whose softening point is 60 ° C. lower than the softening point of the surface transparent protective layer (PET, softening point 250 ° C.), and the elongation at the molding temperature is It has been found that by being about 700% or more, there is an effect of reducing a decrease in photoelectric conversion efficiency due to a decrease in reflectance.

  Furthermore, it was found that if a low Tg acrylic resin having a low softening point is used as the first transparent protective layer and the second transparent protective layer, a photoelectric conversion device with further reduced photoelectric conversion efficiency can be produced.

  In addition, this invention is not limited to said embodiment and Example, A various change can be given in the range which does not deviate from the summary of this invention.

It is sectional drawing which shows the photoelectric conversion apparatus of this Embodiment. It is sectional drawing of the light reflection member in the photoelectric conversion apparatus of this Embodiment. It is a see-through plan view of the photoelectric conversion device of the present embodiment. It is sectional drawing of the photoelectric conversion module of this Embodiment.

Explanation of symbols

1: Conductive substrate 2: Crystalline semiconductor particle 3: Semiconductor part 4: Insulating layer 5: Translucent conductive layer 7: Light reflecting member 10: Surface transparent protective layer 11: Second transparent protective layer 12: Light reflective metal Layer 13: First transparent protective layer 14: Substrate

Claims (9)

A conductive substrate;
A plurality of crystalline semiconductor particles bonded to the upper surface of the conductive substrate at intervals,
A concave mirror-shaped light reflecting member disposed between the crystal semiconductor particles,
The light reflecting member includes a concave mirror-shaped base, a first transparent protective layer made of resin sequentially formed on the light reflecting surface of the base, a light reflective metal layer, a second transparent protective layer made of resin, and a resin. A surface transparent protective layer comprising:
The first and second transparent protective layers have a softening point lower than the softening point of the surface transparent protective layer, and an elongation at a deformable temperature is an elongation at a deformable temperature of the surface transparent protective layer. Larger photoelectric conversion device.   2. The first and second transparent protective layers according to claim 1, wherein the softening point is 60 ° C. or more lower than the softening point of the surface transparent protective layer, and the elongation at a deformable temperature is 700% or more. Photoelectric conversion device.   The photoelectric conversion device according to claim 1, wherein the surface transparent protective layer is made of polyethylene terephthalate.   The photoelectric conversion device according to claim 1, wherein at least one of the first and second transparent protective layers is made of an acrylic resin.   The photoelectric conversion device according to claim 4, wherein the acrylic resin has a glass transition point of 60 ° C. to 80 ° C.   The photoelectric conversion device according to claim 1, wherein the light reflective metal layer includes at least one of silver and aluminum.   The photoelectric conversion device according to claim 1, wherein the substrate is made of polycarbonate.   The photoelectric conversion device according to any one of claims 1 to 7, wherein the light-reflective metal layer has an acute-angled pointed portion at a boundary between concave mirrors in a longitudinal section.   The photoelectric conversion device according to any one of claims 1 to 8, wherein the surface transparent protective layer has a convex curved surface at a boundary between concave mirrors in a longitudinal section.