JP2010186845A - Resin composition, wavelength conversion composition, wavelength conversion layer, and photovoltaic device including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wavelength conversion composition uniformly dispersing a wavelength conversion substance therein, to provide a mold body of the same, and to provide a photovoltaic device including the same. <P>SOLUTION: In this transparent resin composition with two or more kinds of nanoparticles dispersed in a resin, the average diameter of primary particles of the nanoparticles is preferably 1-60 nm; the nanoparticles are two or more kinds of particulates selected from semiconductor particulates, oxide particulates with rare-earth ions doped therein and silica particulates; and each semiconductor particulate is a zinc oxide semiconductor particulate. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a resin composition and a wavelength conversion composition. In particular, the wavelength conversion composition is used in a wavelength conversion layer provided in a photovoltaic device to convert the wavelength of light and supply it to the photovoltaic layer of the photovoltaic device.

  Photovoltaic devices are used as solar cells that photoelectrically convert sunlight to extract electrical energy. As this type of photovoltaic device, those using single crystal silicon or amorphous silicon as a photovoltaic layer for converting light into electromotive force are the mainstream. In the case of these photovoltaic devices, the spectral sensitivity is limited to the substantially visible light region, and it is not possible to efficiently convert regions other than visible light, such as the ultraviolet region and the infrared region, among the solar rays into electric energy.

Therefore, as a technique for increasing the conversion efficiency into electric energy in the photovoltaic device, Patent Document 1 discloses that in the photovoltaic device, europium (Eu ^{3+) is} used as a wavelength conversion substance on the light incident side surface of the photovoltaic layer. ), A glass plate in which rare earth ions such as samarium (Sm ²⁺ ) and terbium (Tb ²⁺ ) are blended is described. As a result, the ultraviolet region of the sunlight is converted into the visible light region and supplied to the photovoltaic layer.

Patent Document 2 describes that in a photovoltaic device, europium (Eu ³⁺ ) is doped as a wavelength conversion substance in a non-reflective film provided on the light incident side surface of the photovoltaic layer. . In this photovoltaic device, in order to uniformly disperse europium (Eu ³⁺ ) in the non-reflective film, formation in the non-reflective film and injection of europium (Eu ³⁺ ) are repeated a plurality of times. As a result, the ultraviolet region of the sunlight is converted into the visible light region and supplied to the photovoltaic layer.
Further, Patent Document 3 includes a description of using semiconductor fine particles such as CdSe, CdTe, GaN, Si, InP, and ZnO or particles in which they are made into a core-shell type as a wavelength conversion substance. As a method for synthesizing semiconductor fine particles, there are a sputtering method, an electric furnace heating method, an etching method, a spray pyrolysis method, an anodic oxidation method, and a spray drying method (see Patent Documents 4, 5, and 6). Non-Patent Document 2 describes the synthesis of zinc oxide semiconductor fine particles by a sol-gel method. Non-Patent Document 3 describes a method of producing composite fine particles of zinc oxide semiconductor fine particles and silica fine particles by a spray drying method.

JP 2003-142716 A (paragraphs 0021 and 0022, and FIG. 1) JP-A-8-204222 (paragraph 0010 and FIG. 1) JP 2006-216560 A JP 2006-70089 A JP-A-6-90019 (paragraph 0009) JP 2003-019427 A

Clean Technology, 7, 27-30 (2007) J. et al. Am. Chem. Soc. , 113, 2826-2833 (1991) J. et al. Appl. Phys. 89 (11), 6431-6434 (2001)

By the way, in order to improve the conversion efficiency into electric energy by providing the wavelength conversion layer as described above, it is necessary to improve the wavelength conversion efficiency without impairing the light transmittance in the wavelength conversion layer. For this reason, it is necessary to uniformly disperse the wavelength conversion substance in the wavelength conversion layer. However, in the photovoltaic device described in Patent Document 1, there is a possibility that the wavelength conversion material aggregates when the glass substrate is formed, and it is difficult to uniformly disperse the wavelength conversion material. On the other hand, the photovoltaic device described in Patent Document 2 can disperse the wavelength converting substance uniformly to some extent, but it is necessary to repeat the formation of the nonreflective film layer and the injection of the wavelength converting substance a plurality of times. There is a problem that the process becomes complicated and the manufacturing cost increases. Moreover, although the wavelength conversion is performed in the photovoltaic device described in Patent Document 3, it is not possible to sufficiently improve the energy conversion efficiency of the photovoltaic device because of toxic problems and low light extraction efficiency. There was a problem.
The object of the present invention has been made in view of the above-mentioned problems, a wavelength conversion composition capable of uniformly dispersing a wavelength conversion substance without increasing the manufacturing cost, a molded body thereof, and a light provided with the molded body. It is to provide an electromotive device. At the same time, an object of the present invention is to provide a resin composition in which nanoparticles are uniformly dispersed when the wavelength converting substance is nanoparticles.

  The first characteristic configuration of the present invention is that it is a transparent resin composition in which two or more kinds of nanoparticles are dispersed in a resin.

  The 2nd characteristic structure of this invention exists in the point whose average primary particle diameter of the said 2 or more types of nanoparticle is 1-60 nm.

  By setting the average primary particle diameter of the nanoparticles to 1 to 60 nm as in this configuration, the light transmittance of the resin composition is not impaired.

  A third characteristic configuration of the present invention is that the nanoparticles are at least two or more kinds of fine particles selected from semiconductor fine particles, oxide fine particles doped with rare earth ions, and silica fine particles.

  When the nanoparticles are at least two or more kinds of fine particles selected from semiconductor fine particles, rare earth ion-doped oxide fine particles, and silica fine particles, functions such as wavelength conversion, light emission, and conductivity can be imparted. At the same time, the transparency of the resin composition is further improved.

  A fourth characteristic configuration of the present invention is that the semiconductor fine particles are zinc oxide semiconductor fine particles.

  By selecting zinc oxide semiconductor fine particles as the semiconductor fine particles, sunlight in the ultraviolet region can be efficiently converted into light in the green visible region.

  According to a fifth feature of the present invention, the rare earth contains one or more selected from the group consisting of europium (Eu), erbium (Er), dysprodium (Dy), and neodymium (Nd). There is a point.

  By using the above-mentioned substances as rare earths, ultraviolet rays and infrared rays can be efficiently converted into visible light.

  A sixth characteristic configuration of the present invention is that the oxide fine particles are oxide fine particles containing at least one element selected from yttrium, vanadium, and bismuth.

  With this configuration, it is possible to efficiently absorb ultraviolet rays contained in sunlight.

  A seventh characteristic configuration of the present invention is that the silica fine particles are colloidal silica.

  With this configuration, the dispersibility of the semiconductor fine particles and the oxide fine particles doped with rare earth ions is improved, and the transparency of the resin composition is improved.

  According to an eighth characteristic configuration of the present invention, the method for dispersing the nanoparticles is to produce composite fine particles in which two or more kinds of fine particles are uniformly combined, mixed with resin, and mechanically crushed and dispersed. The point is in the way.

  With this configuration, since different types of nanoparticles are uniformly combined in the composite fine particles, the same nano-sized nanoparticles are prevented from being aggregated and difficult to disperse, and mechanically crushed and dispersed easily. Thereby, a nanoparticle can be disperse | distributed to resin and a transparent resin composition can be obtained.

  A ninth characteristic configuration of the present invention is that the resin is an acrylic resin or an epoxy resin.

  With this configuration, the resin composition can be cured by light or heat and molded.

  A tenth characteristic configuration of the present invention is an ethylene-vinyl acetate copolymer resin.

  With this configuration, it can be used as a sealing resin used in solar cells.

  The eleventh characteristic configuration of the present invention is that a silicon compound is contained in the resin composition.

  With this configuration, the affinity between the resin and the nanoparticles is improved. Thereby, a nanoparticle can be disperse | distributed to resin and a transparent resin composition can be obtained.

  A twelfth characteristic configuration of the present invention is that the silicon compound is an aminosilane coupling agent.

  With this configuration, the affinity between the resin and the nanoparticles is improved. Thereby, a nanoparticle can be disperse | distributed to resin and a transparent resin composition can be obtained.

  A thirteenth characteristic configuration of the present invention is that the aminosilane coupling agent is N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane.

  With this configuration, the affinity between the resin and the nanoparticles is improved. Thereby, a nanoparticle can be disperse | distributed to resin and a transparent resin composition can be obtained.

  The 14th characteristic structure of this invention exists in the point which contains at least 1 or more types chosen from the aluminum compound, the gallium compound, the indium compound, the phosphorus compound, and the tin compound in the said resin composition.

  With this configuration, conductivity can be imparted to the resin composition. Thereby, a transparent conductive film can be produced.

  A fifteenth characteristic configuration of the present invention is that the resin composition has a function of converting a wavelength of absorbed light.

  With this configuration, light can be effectively used in combination with solar cells, lighting devices, and LED devices. By using together with solar cells, it becomes possible to convert ultraviolet light and infrared light that are not used in solar cells into the visible light region used by solar cells, and it is possible to improve the conversion efficiency of solar cells Become.

  A sixteenth characteristic configuration of the present invention is that it is a wavelength conversion layer formed by molding the wavelength conversion composition.

  With this configuration, light can be effectively used in combination with solar cells, lighting devices, and LED devices. By using together with solar cells, it becomes possible to convert ultraviolet light and infrared light that are not used in solar cells into the visible light region used by solar cells, and it is possible to improve the conversion efficiency of solar cells Become.

  A seventeenth characteristic configuration of the present invention is a photovoltaic device including the wavelength conversion layer.

  With this configuration, it becomes possible to convert ultraviolet light and infrared light that are not used in the photovoltaic device into the visible light region used by the photovoltaic device, thereby improving the conversion efficiency of the photovoltaic device. This makes it possible to manufacture a highly efficient solar cell.

  The 18th characteristic structure of this invention exists in the point in which the said wavelength conversion layer has an uneven structure in the surface of a photovoltaic apparatus.

With this configuration, the light absorption rate of sunlight, the light extraction efficiency of the illumination device and the LED device are improved, and the light can be effectively used.

  A nineteenth characteristic configuration of the present invention is that the uneven structure has an uneven structure having a height difference of 300 nm to 100 μm.

With this configuration, the light absorption rate of sunlight, the light extraction efficiency of the illumination device and the LED device are improved, and the light can be effectively used.

  A twentieth characteristic configuration of the present invention is that an in-plane period of the concavo-convex structure is 300 nm to 50 μm.

With this configuration, the light absorption rate of sunlight, the light extraction efficiency of the illumination device and the LED device are improved, and the light can be effectively used.

  A twenty-first characteristic configuration of the present invention is that the wavelength conversion layer is formed by an ink jet method.

With this configuration, application can be performed at normal pressure without using a vacuum, and various uneven shapes, multilayer structures, and the like can be easily manufactured. This makes it possible to produce a highly functional wavelength conversion layer at low cost.

The wavelength conversion layer used in the photovoltaic device is formed by an ink jet method.
With this configuration, application can be performed at normal pressure without using a vacuum, and various uneven shapes, multilayer structures, and the like can be easily manufactured. This makes it possible to produce a highly functional wavelength conversion layer at low cost. Therefore, it is possible to manufacture a solar cell with low cost and high efficiency.

1 shows a photovoltaic device according to the present invention. Diagram showing details of wavelength conversion layer The figure which shows another embodiment of the photovoltaic apparatus which concerns on this invention The figure which shows another embodiment of the photovoltaic apparatus which concerns on this invention The figure which shows embodiment of the photovoltaic apparatus in which the wavelength conversion layer which concerns on this invention has an uneven structure The figure which shows another embodiment of the photovoltaic apparatus in which the wavelength conversion layer which concerns on this invention has an uneven structure The figure which shows another embodiment of the photovoltaic apparatus in which the wavelength conversion layer which concerns on this invention has an uneven structure The figure which shows another embodiment of the photovoltaic apparatus in which the wavelength conversion layer which concerns on this invention has an uneven structure The figure which shows another embodiment of the photovoltaic apparatus in which the wavelength conversion layer which concerns on this invention has an uneven structure

Although the resin composition of the present invention can be applied to various uses, embodiments in the case of being used mainly as a wavelength conversion composition will be described below with reference to the drawings.
The resin composition of the present invention is characterized by being transparent. In the coating film having a thickness of 100 μm, the resin composition having a parallel light transmittance of 90% or more is transparent.
[Embodiment 1]
FIG. 1 shows a photovoltaic device 1 having a wavelength conversion layer 3 made of a wavelength conversion composition according to the present invention. The photovoltaic device 1 includes a photovoltaic layer 2 that generates an electromotive force by light, and a wavelength conversion layer 3 made of a wavelength conversion composition is provided on the light incident surface side of the photovoltaic layer 2.

  The photovoltaic layer 2 generates an electromotive force by light. A semiconductor layer composed of a p-type semiconductor layer, a vacuum semiconductor layer, and an n-type semiconductor layer, a sealing material such as an EVA resin composition, one side of the semiconductor layer or Transparent electrode layers provided on both sides are provided. The semiconductor layer is not particularly limited. For example, single crystal silicon, amorphous silicon, a compound semiconductor, or the like can be used. The transparent electrode is not particularly limited, and is made of, for example, ITO or tin oxide. The configuration of the photovoltaic device 1 is not limited to this, and the wavelength conversion composition of the present invention can be applied to various photovoltaic devices 1. In particular, when the wavelength conversion layer 3 is provided on the commercially available photovoltaic layer 2, a glass, a transparent electrode, a non-reflective layer, a protective layer, or the like may be further formed on the photovoltaic layer 2. In this case, the wavelength conversion layer 3 is formed on or below glass, a transparent electrode, a non-reflective layer, a protective layer, or the like.

  In this embodiment, the wavelength conversion layer 3 converts sunlight in the ultraviolet region into the visible light region. As shown in FIG. 2, the wavelength conversion layer 3 includes first nanoparticles 6 dispersed in a resin 5, second nanoparticles 8 and other nanoparticles (not shown) as required. Is provided. Transparent resin composition in which nanoparticles are dispersed in resin 5 by preparing composite fine particles in which two or more kinds of nanoparticles are uniformly compounded, mixing them with resin, mechanically crushing and dispersing them Can be obtained. The wavelength conversion layer 3 is formed, for example, by applying the transparent resin composition to the surface of the photovoltaic layer 2 and curing it. For this reason, the wavelength conversion layer 3 can be formed only by apply | coating the wavelength conversion composition which is a transparent resin composition to the commercially available photovoltaic apparatus 1, for example, and making it photocure.

  Hereinafter, the detail of the wavelength conversion composition which is a transparent resin composition which comprises the wavelength conversion layer 3 is demonstrated. This wavelength conversion composition is constituted by containing two or more kinds of nanoparticles in the resin 5.

  The resin 5 is a photocurable resin, a thermosetting resin, or a thermoplastic resin, and is not particularly limited as long as it transmits light. For example, an acrylic resin, an epoxy resin, a silicon resin, and ethylene-vinyl acetate are used. Polymerized resin etc. are mentioned.

  Epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, naphthalene type epoxy resins or their hydrogenated products, epoxy resins having a dicyclopentadiene skeleton, and epoxy having a triglycidyl isocyanurate skeleton. Examples thereof include resins, epoxy resins having a cardo skeleton, and epoxy resins having a polysiloxane structure. When heat resistance is required, such as for directly forming a photovoltaic layer such as amorphous silicon or an antireflection film, those having an alicyclic structure are preferable. Examples of the alicyclic epoxy resin include 3,4-epoxycyclohexylmethyl 3 ′, 4′-epoxycyclohexanecarboxylate, 1,2,8,9-diepoxy limonene, and ε-caprolactone oligomer at both ends of 3,4- Examples thereof include an ester-bonded epoxy cyclohexyl methanol and 3,4-epoxycyclohexanecarboxylic acid, a hydrogenated biphenyl skeleton, and an alicyclic epoxy resin having a hydrogenated bisphenol A skeleton.

  The acrylic resin is not particularly limited as long as it is a (meth) acrylate having two or more functional groups, but heat resistance is required for directly forming a photovoltaic layer or an antireflection film such as amorphous silicon. When doing, what has an alicyclic structure is preferable. As the (meth) acrylate having an alicyclic structure, an acrylic resin obtained by polymerizing at least one (meth) acrylate selected from Chemical Formula (1) and Chemical Formula (2) is particularly preferable.

（化（１）中、Ｒ¹及びＲ²は、互いに異なっていても良く、水素原子又はメチル
基を示す。ａは１又は２を示し、ｂは０又は１を示す。）

(In the chemical formula (1), R ¹ and R ² may be different from each other and represent a hydrogen atom or a methyl group. A represents 1 or 2, and b represents 0 or 1.)

More preferably, in the chemical formula (1), dicyclopentadienyl diacrylate having a structure in which R ¹ and R ² are hydrogen, a is 1 and b is 0, and in the general formula (2), X is —CH ₂ perhydro-1,4; 5,8-dimethananaphthalene-2,3,7- (oxymethyl) triacrylate having a structure in which OCOCH═CH ₂ , R ³ , R ⁴ is hydrogen and p is 1; X, R ³ and R ⁴ are all hydrogen and p is at least one acrylate selected from acrylates having a structure of 0 or 1, and most preferably, X, This is norbornane dimethylol diacrylate having a structure in which R ³ and R ⁴ are all hydrogen and p is 0.

The ethylene-vinyl acetate copolymer resin preferably has a VA content of 20 to 50%, more preferably 25 to 35% for post-crosslinking when used as a sealing material for solar cells. Is.

  The average primary particle size of the two or more kinds of nanoparticles used in the present invention is preferably 1 to 60 nm, and more preferably 2 to 30 nm. If the average primary particle size is less than the lower limit, the wavelength conversion function and the conductive function cannot be sufficiently exhibited. On the other hand, when the average primary particle diameter exceeds the upper limit, the transparency of the resin composition is significantly impaired.

  The nanoparticles are preferably at least two kinds of fine particles selected from semiconductor fine particles, oxide fine particles doped with rare earth ions, and silica fine particles. By using these, a transparent resin composition dispersed in the resin can be obtained.

  Examples of the semiconductor fine particles include compound semiconductor fine particles and silicon semiconductor fine particles. The compound semiconductor fine particles include group III-V semiconductor fine particles and group II-VI semiconductor fine particles. Among these, zinc oxide semiconductor fine particles are preferable from the viewpoints of cost, toxicity and the like.

  The rare earth used in the oxide fine particles doped with rare earth ions is not particularly limited as long as it is a rare earth, but europium (Eu), erbium (Er), dysprodium (Dy), and neodymium (Nd) are preferable, and more preferable. Is preferably europium (Eu). By using europium (Eu) as a rare earth, a function of absorbing ultraviolet rays and emitting red visible light is given. Thereby, when it uses for a solar cell etc., light can be utilized now effectively and the conversion efficiency of a solar cell improves.

  The oxide fine particles of oxide fine particles doped with rare earth ions are not particularly limited as long as they are oxide fine particles, but are oxides containing at least one element selected from silica, zirconia, yttrium, vanadium, and bismuth. Fine particles are preferable, and oxide fine particles containing at least one element selected from yttrium, vanadium, and bismuth are more preferable. Most of sunlight in the ultraviolet region that reaches the ground has a wavelength of 300 nm to 400 nm. By containing at least one element selected from yttrium, vanadium, and bismuth, these can be effectively absorbed and converted into visible light.

  The silica fine particle is not particularly limited as long as it is a fine particle mainly composed of silica, but colloidal silica is preferable from the viewpoint of cost and handling.

  As a method of dispersing two or more kinds of nanoparticles in the resin 5, a composite fine particle obtained by uniformly compounding two or more kinds of nanoparticles is prepared, mixed with the resin, mechanically crushed and dispersed. Is preferred. Usually, once the nanoparticles are aggregated, it is extremely difficult to disperse them in the resin. However, by producing composite fine particles in which two or more kinds of nanoparticles are uniformly composited, the same nanoparticles are surrounded by different kinds of nanoparticles, and aggregation of the same nanoparticles can be prevented. Thereby, it mixes with resin and is disperse | distributed mechanically, it crushes easily and each nanoparticle disperse | distributes by nano order.

  The method for producing the composite fine particles is not particularly limited. For example, sol-gel method, complex polymerization method, PVA method, complex homogeneous precipitation method, reverse micelle method, colloidal precipitation method, hot soap method supercritical hydrothermal method, solvothermal method , Spray pyrolysis method, spray drying method and the like. These may be used alone or in combination. From the viewpoint of cost and mass productivity, the sol-gel method, the reverse micelle method, the spray pyrolysis method, the spray drying method and the like are preferable, and the spray drying method is more preferable.

  The mechanical dispersion method is not particularly limited as long as it is a dispersion method using an apparatus that gives mechanical fracture energy such as shear or impact, but a dispersion method using a ball mill, a bead mill, a biaxial kneader, or the like can be given. It is done. Among these, a dispersion method using a bead mill and a twin-screw kneader that can be processed continuously with high fracture energy is preferable.

  The mixing ratio of two or more kinds of nanoparticles in the composite fine particles can be adjusted according to the purpose. The content of all nanoparticles in the resin is preferably 1 to 50 vol%, and more preferably 1 to 30 vol%.

In order to uniformly disperse two or more kinds of nanoparticles in the resin, it is preferable to contain a silicon compound in the resin composition. The silicon compound is not particularly limited as long as it is a compound containing silicon, but an aminosilane coupling agent is preferable, and N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane is more preferable.

In order to impart a conductive function, the resin composition may contain at least one selected from an aluminum compound, a gallium compound, an indium compound, a phosphorus compound, and a tin compound. When zinc oxide semiconductor fine particles are contained in the resin, the zinc oxide fine particles may be doped with aluminum or gallium. As a method for doping, when producing zinc oxide semiconductor fine particles by the sol-gel method in the same manner as in Non-Patent Document 2, an aluminum compound such as almatrane, aluminum (III) s-butoxide, or the following compound is used in combination. Can be produced.
M [N (OR) ₄ ] ₃
Here, M is at least one element selected from Al, Ga, and In, N is at least one element selected from Al and Ga, and R is a hydrocarbon having 1 to 5 carbon atoms. .
The above aluminum compound, gallium compound, indium compound, phosphorus compound, and tin compound may be added in the process of mechanically crushing and dispersing the composite fine particles.

[Embodiment 2]
In the above-described embodiment, as shown in FIG. 3, as the wavelength conversion layer 3, the first wavelength conversion layer 31 that converts sunlight in the ultraviolet region into the visible light region and the sunlight in the infrared region into the visible light region. You may provide the 2nd wavelength conversion layer 32 to convert. In this embodiment, as shown in FIG. 3, the first wavelength conversion layer 31 and the second wavelength conversion layer 32 are formed in this order from the light incident side. The longer the wavelength, the more easily light is transmitted. Accordingly, the first wavelength conversion layer 31 for converting the short wavelength ultraviolet region into the visible light region is provided on the light incident side, and the second wavelength conversion layer 32 for converting the long wavelength infrared region into the visible light region is provided on the inner side. By providing in, the efficiency of wavelength conversion can be improved.

[Embodiment 3]
Further, as the wavelength conversion layer 3, a first wavelength conversion layer 3 that converts sunlight in the ultraviolet region into a visible light region and a second wavelength conversion layer 3 that converts sunlight in the infrared region into a visible light region are provided. In this case, as shown in FIG. 4, the first wavelength conversion layer 3 is formed on the light incident surface side of the photovoltaic layer 2, the second wavelength conversion layer 3 is formed on the back surface of the photovoltaic layer 2, and A reflective layer 7 may be provided on the opposite side of the second wavelength conversion layer 3 from the photovoltaic layer 2 side.

[Embodiment 4]
In the above-described embodiment, the example in which the wavelength conversion composition is applied to the photovoltaic device 1 and cured to form the wavelength conversion layer 3 has been described, but the present invention is not limited thereto. For example, the wavelength conversion layer 3 may be formed by forming a film obtained by curing the wavelength conversion composition and providing the film on the photovoltaic device 1 with an adhesive or the like.

[Embodiment 5]
In the above-described embodiment, the wavelength conversion layer 3 may be installed so as to have an uneven structure in the plane of the photovoltaic device. Thereby, light transmission loss, anti-loss at the interface between the wavelength conversion layer and the photovoltaic device can be reduced, and light converted by the wavelength conversion layer can be efficiently supplied to the photovoltaic device.

  The height difference of the concavo-convex structure is preferably 300 nm to 100 μm, more preferably 1 to 50 μm, and most preferably 10 to 50 μm from the balance between absorption of sunlight from the oblique direction and cost. The height difference of the concavo-convex structure can be measured using a microscope such as an atomic force microscope, a confocal microscope, or a laser microscope.

  The in-plane period of the concavo-convex structure is preferably 300 nm to 50 μm. It is preferable that the period is substantially the same as the light absorption wavelength region of the wavelength conversion composition. The indentation periods in the in-plane perpendicular direction (X direction, Y direction) may be the same or different. There may also be variations in the in-plane cycle in the same direction. The in-plane period of the concavo-convex structure can be obtained by Fourier transforming image information measured using a microscope such as an atomic force microscope, a confocal microscope, or a laser microscope.

  As the shape of the concavo-convex structure, various shapes such as dots, microlenses, L & S, honeycombs, cells, square pyramids, moth eyes, and cones can be used. From the viewpoint of cost and efficiency, the shape of a dot, microlens, L & S, cell, or quadrangular pyramid is preferable, and the shape of a dot or microlens is more preferable. Examples of the above uneven structure are shown in FIGS.

  The uneven structure can be formed on the surface of the photovoltaic device, the surface opposite to the photovoltaic device side, or both surfaces. When forming on the surface of the photovoltaic device side, after forming a fine uneven shape in advance on the surface of the photovoltaic device with a wavelength conversion composition or other resin composition, and then applying the wavelength conversion composition on it good. In this case, the in-plane period of the uneven shape on the surface on the photovoltaic device side is preferably in the range of 300 nm to 1 μm. When forming an uneven structure on both the surface opposite to the photovoltaic device and the surface on the photovoltaic device side, the in-plane period of the uneven shape on the surface on the photovoltaic device side is opposite to that on the photovoltaic device. It is preferable to make it smaller than the in-plane period of the irregular shape of the surface.

  The concavo-convex structure may be a wavelength conversion composition in which the adjacent concavo-convex is the same or a different wavelength conversion composition. When the light absorption wavelength range of the wavelength conversion composition is relatively narrow, by setting the wavelength conversion composition of adjacent concavities and convexities to be different for the purpose of, for example, widening the light absorption wavelength range, an efficient photovoltaic device It is possible to improve the power generation efficiency.

  After forming the concavo-convex structure, another resin composition can be overcoated on the concavo-convex structure. Thereby, declines, such as dirt resistance and durability, can be controlled.

[Embodiment 6]
In the above-described embodiment, various methods such as spray, dispenser, and ink jet can be used as the method for applying the wavelength conversion layer 3. In consideration of application speed, apparatus cost, fine shape drawing accuracy, etc., application using an ink jet method is preferable, and among them, a piezo method ink jet capable of dealing with relatively high viscosity is preferable.
In addition, in the ink jet method, it may be difficult to provide an uneven shape of 10 μm or less. In such a case, it is also possible to form a concavo-convex structure using a technique such as nanoimprint.

Hereinafter, the contents of the present invention will be described in detail by way of examples. However, the present invention is not limited to the following examples unless it exceeds the gist.

[Example 1]
(1) Composite fine particles containing two or more kinds of nanoparticles (zinc oxide semiconductor fine particles and silica fine particles) According to the methods described in Non-Patent Documents 2 and 3, composite fine particles were prepared as follows. First, an ethanol solution of zinc oxide semiconductor fine particles was prepared. The prepared solution emitted green light when irradiated with ultraviolet rays (center wavelength: 365 nm). The average primary particle size of the zinc oxide semiconductor fine particles was about 3 nm. Next, using the ethanol solution of the zinc oxide semiconductor fine particles and the ethanol solution of colloidal silica having an average primary particle size of 5 nm, spraying is performed so that the volume ratio of the zinc oxide fine particles to the colloidal silica of the composite fine particles to be prepared is 1: 1. Composite fine particles were prepared by a drying method. The size of the produced composite fine particles was mainly micron-sized, but some of them were less than 1 μm.

(2) Resin composition Norbornane dimethylol diacrylate having a structure in which X, R ³ , and R ⁴ are all hydrogen and p is 0 in the general formula (2) [Prototype No. TO-2111; Toagosei Co., Ltd. Manufactured), N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, and composite fine particles containing two or more kinds of nanoparticles (zinc oxide semiconductor fine particles and silica fine particles) prepared in (1) by a bead mill. Stir for minutes to disperse. The mixing ratio of norbornane dimethylol diacrylate, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, and composite fine particles was 8: 1: 1 by volume. It was confirmed with the naked eye that the resin composition after the dispersion treatment has the same degree of transparency as that of the resin alone.

(3) Transparency evaluation (3-1) Transparency and linear expansion coefficient The resin composition obtained in (2) and the photocatalyst are mixed and poured into a 0.15 mm thick frame created on a glass plate. A glass plate was placed on the top and filled into the frame. The resin composition was cured by irradiating UV light of about 500 mJ / cm ² from both sides of the glass plate, and the sheet was peeled from the glass. Each of the obtained sheets was heated in a vacuum oven at about 100 ° C. for 3 hours, and further heated at about 275 ° C. for 3 hours to obtain a sheet-like sample. As a result of measuring the thickness of the obtained sheet-like sample with a micrometer, it was 105 μm.
As a result of measuring haze measurement using NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd. with respect to the sheet-like sample, it was 0.5, and as a result of measuring parallel light transmittance with a spectrophotometer UV-2400PC (manufactured by Shimadzu Corporation), The parallel light transmittance was 93%. Even with the naked eye, it was confirmed that the sheet was very transparent.

(3-2) Power generation efficiency The resin composition obtained in (2) and the photocatalyst are mixed on the surface of a commercially available crystalline silicon solar battery cell, and a micro as shown in FIG. It was applied in a lens shape and irradiated with UV light to obtain the final solar battery cell. The diameter of the microlens shape obtained by microscopic observation, the height difference of the concavo-convex structure, and the period were about 30 μm, about 10 μm, and about 40 μm, respectively. When the power generation efficiency of this cell was measured, it was confirmed that the power generation efficiency was improved by about 3%.

  The resin composition of the present invention can be applied as a wavelength conversion composition to a photovoltaic device that converts light into electrical energy. In addition, since light having a wavelength in the visible region is emitted by application of voltage, electron beam irradiation, ultraviolet rays of sunlight, near infrared rays, or the like, it can be suitably used for bioimaging, security paints, displays, lighting, and the like. When nanocrystals are used as the wavelength conversion substance, they can be used for photovoltaic devices themselves.

DESCRIPTION OF SYMBOLS 1 Photovoltaic device 2 Photovoltaic layer 3 Wavelength conversion layer 4 Composite fine particle 5 Resin 6 1st nanoparticle 7 Reflective layer 8 2nd nanoparticle

Claims (22)

A transparent resin composition in which two or more kinds of nanoparticles are dispersed in a resin.   The resin composition according to claim 1, wherein the nanoparticles have an average primary particle diameter of 1 to 60 nm.   The resin composition according to claim 1, wherein the nanoparticles are at least two kinds of fine particles selected from semiconductor fine particles, oxide fine particles doped with rare earth ions, and silica fine particles.   The resin composition according to claim 3, wherein the semiconductor fine particles are zinc oxide semiconductor fine particles.   The resin composition according to claim 3, wherein the rare earth is a substance containing one or more selected from the group consisting of europium (Eu), erbium (Er), dysprodium (Dy), and neodymium (Nd). object.   The resin composition according to claim 3, wherein the oxide fine particles are oxide fine particles containing at least one element selected from yttrium, vanadium, and bismuth. The resin composition according to claim 3, wherein the silica fine particles are colloidal silica. The method of dispersing the nanoparticles is a method of preparing composite fine particles in which two or more kinds of nanoparticles are uniformly combined, mixing the composite fine particles with a resin, mechanically crushing and dispersing the composite fine particles. The resin composition as described in any one of -7.   The resin composition according to any one of claims 1 to 8, wherein the resin is an acrylic resin or an epoxy resin.   The resin composition according to any one of claims 1 to 8, wherein the resin is an ethylene-vinyl acetate copolymer resin. The resin composition according to any one of claims 1 to 10, further comprising a silicon compound in the resin composition. The resin composition according to claim 11, wherein the silicon compound is an aminosilane coupling agent.   The resin composition according to claim 12, wherein the aminosilane coupling agent is N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane.   The resin composition according to any one of claims 1 to 13, wherein the resin composition contains at least one selected from an aluminum compound, a gallium compound, an indium compound, a phosphorus compound, and a tin compound. object.   The wavelength conversion composition according to any one of claims 1 to 14, wherein the resin composition has a function of converting a wavelength of absorbed light. The wavelength conversion layer formed by shape | molding the wavelength conversion composition of Claim 15.   A photovoltaic device comprising the wavelength conversion layer according to claim 16. The photovoltaic device according to claim 17, wherein the wavelength conversion layer has an uneven structure in a plane of the photovoltaic device. The photovoltaic device according to claim 18, wherein the uneven structure has an uneven structure having a height difference of 300 nm to 100 μm. The photovoltaic device according to claim 18 or 19, wherein an in-plane period of the concavo-convex structure is 300 nm to 50 µm. The wavelength conversion layer according to claim 16, which is formed by an inkjet method. The photovoltaic device according to any one of claims 17 to 20, wherein the wavelength conversion layer is formed by an inkjet method.

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