JP2006210229A - Dye-sensitized solar battery and manufacturing method of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dye-sensitized solar battery capable of improving light utilization efficiency, and a manufacturing method of the same. <P>SOLUTION: The dye-sensitized solar battery has a transparent substrate 1, a phosphor layer 10, and a middle layer 11 arranged between them. On condition that arithmetic mean of the roughness of the phosphor layer 10 at main face side is Ra, refractive index of the phosphor layer is n<SB>1</SB>, refractive index of the middle layer 11 is n<SB>2</SB>, the dye-sensitized solar battery 14 fulfills at least either a relation (a) or a relation (b) shown below. (a) 2 nm≤Ra≤1 μm, and n<SB>1</SB>-0.2≤n<SB>2</SB>, (b) 40 nm≤Ra≤1 μm, and n<SB>1</SB>-0.5≤n<SB>2</SB>. For example, the dye-sensitized solar battery 14 can be manufactured by forming the phosphor layer 10 through the middle layer 11 while applying the above physical relations to a light receiving face side of the transparent substrate 1 of a solar battery main body 13. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to a dye-sensitized solar cell and a method for manufacturing the same, and more particularly to a dye-sensitized solar cell including a phosphor layer and a method for manufacturing the same.

In recent years, photovoltaic power generation has attracted attention as a clean energy source that replaces fossil fuels from the viewpoint of energy problems and environmental problems. Silicon-based solar cells have been put into practical use so far, but in order to reduce battery manufacturing costs, research on dye-sensitized solar cells using readily available titanium dioxide as a key component for photoelectric conversion is actively conducted. It is.

Dye-sensitized solar cells are a technology that uses a photosensitizing dye that absorbs in the visible light region, but at present, it is used for the absorption wavelength region of the synthesized photosensitizing dye, that is, for photoelectric conversion. The wavelength range of light that can be used is narrow, and the light utilization efficiency is inferior to silicon solar cells.

Although it is expected to synthesize photosensitizing dyes with a wide absorption wavelength range, it is difficult to match energy with the redox potential of titanium dioxide conductors and electrolytes, and it is still wide enough to match silicon solar cells. It has not yet been achieved to synthesize a dye having an absorption wavelength range.

Therefore, from another aspect, as a technology that also uses light outside the absorption wavelength range of the photosensitizing dye in the incident light, a predetermined wavelength conversion is performed on the light receiving surface of the transparent substrate that forms the working electrode of the solar cell. There is a technique of providing a phosphor layer having characteristics (see Patent Document 1).

JP 2004-171815 A

However, since the fluorescence emitted from the phosphor layer does not have directivity as a whole, the ratio of the fluorescence that is totally reflected when entering the solar cell body is increased. For this reason, the conventional dye-sensitized solar cell typified by Patent Document 1 has a problem that the amount of light reaching the photosensitizing dye is small and the light utilization efficiency cannot be sufficiently improved.

Therefore, an object of the present invention is to provide a dye-sensitized solar cell that can reduce total reflection of incident light accompanying wavelength conversion by a phosphor while utilizing wavelength controllability by the phosphor. Another object of the present invention is to provide a method for producing the dye-sensitized solar cell.

The present inventor controls the relationship between the refractive index of the intermediate layer interposed between the transparent substrate and the phosphor layer and the refractive index of the phosphor layer according to the roughness of the surface of the phosphor layer. The present inventors have found that the characteristics of the dye-sensitized solar cell are improved and have completed the present invention.

The dye-sensitized solar cell of the present invention comprises a transparent substrate, a phosphor layer provided on the light receiving surface side of the transparent substrate, and an intermediate layer provided between the transparent substrate and the phosphor layer. A dye-sensitized solar cell having an arithmetic average roughness Ra of the main surface of the phosphor layer on the intermediate layer side, a refractive index of the phosphor layer n ₁ , and a refractive index of the intermediate layer n ₂ , at least one of the following a) and b) is established.
a) 2 nm ≦ Ra ≦ 1 μm and n ₁ −0.2 ≦ n ₂
b) 40 nm ≦ Ra ≦ 1 μm and n ₁ −0.5 ≦ n ₂

From another aspect, the present invention provides a dye-sensitized method comprising a step of providing a phosphor layer via an intermediate layer on the light-receiving surface side of a transparent substrate as a method suitable for producing the dye-sensitized solar cell. In which the arithmetic mean roughness of the main surface of the phosphor layer on the intermediate layer side is Ra, the refractive index of the phosphor layer is n ₁ , and the refractive index of the intermediate layer is n ₂ The following provides a method for producing a dye-sensitized solar cell in which at least one of the following a) and b) is established.
a) 2 nm ≦ Ra ≦ 1 μm and n ₁ −0.2 ≦ n ₂
b) 40 nm ≦ Ra ≦ 1 μm and n ₁ −0.5 ≦ n ₂

In the dye-sensitized solar cell of the present invention, the refractive index of the intermediate layer interposed between the transparent substrate and the phosphor layer according to the roughness of the main surface on the intermediate layer side of the phosphor layer, and the phosphor layer Therefore, the total reflection of incident light accompanying the wavelength conversion by the phosphor can be reduced while utilizing the wavelength controllability by the phosphor. Thereby, the light utilization efficiency in a dye-sensitized solar cell can be improved.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

The dye-sensitized solar cell 14 shown in the cross-sectional view of FIG. 1 has a pair of substrates 1 and 9 facing each other, and conductive films 2 and 8 are provided in contact with the inner main surface of each substrate. Yes. A barrier layer 3 is provided in contact with one conductive film 2, and a catalyst layer 7 is provided in contact with the other conductive film 8. An electrolyte layer 6 is provided in contact with the catalyst layer 7. An oxide semiconductor porous film 4 is provided in contact with the barrier layer 3 and the electrolyte layer 6. In addition, substrate 1
An intermediate layer 11 is provided in contact with the main surface on the outer side (light-receiving surface side), and a phosphor layer 10 is provided in contact with the intermediate layer 11. Hereinafter, a multilayer structure from the substrate 1 to the oxide semiconductor porous film 4 is referred to as a photoelectrode 5, and a multilayer structure from the substrate 9 to the catalyst layer 7 is referred to as a counter electrode 12, from the substrate 1 to the substrate 9. This multilayer structure is called the main body 13 of the dye-sensitized solar cell.

The material of the substrate 1 is preferably the one that can increase the light transmittance of the substrate. For example, a glass sheet or a resin sheet such as polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene sulfide, or polyimide can be used. On the other hand
The substrate 9 may be a substrate with low light transmittance such as a metal plate, or may be a substrate with high light transmittance such as a resin sheet.

As the material of the conductive film 2, a material having high light transmittance and low electrical resistivity is preferable. For example, tin oxide, zinc oxide, ITO (tin-doped indium oxide), FTO (fluorine-doped tin oxide), or the like can be used. On the other hand, as the material of the conductive film 8, a material having a high light transmittance similar to that of the conductive film 2 may be used. For example, copper, nickel, silver, gold, platinum, tantalum, titanium, ruthenium, carbon, or the like may be used. A conductive material having low light transmittance may be used.

The conductive films 2 and 8 are formed by vapor deposition, sputtering, chemical vapor deposition (CVD).
Method), a coating method, and a sol-gel method. Further, a conductive thin film made of a conductive material such as copper may be disposed between the substrate 1 and the conductive film 2 to the extent that the transparency is not impaired. When the substrate 9 is a metal plate, the conductive film 8 may be omitted.

The oxide semiconductor porous film 4 is a porous structure (thickness: about 0.1 to 100 μm) having countless fine pores inside and a fine uneven structure on the surface. Examples of the material of the porous film 4 include metal oxide fine particles (volume average particles) such as titanium oxide, tin oxide, tungsten oxide, zinc oxide, zirconium oxide, niobium oxide, indium oxide, yttrium oxide, lanthanum oxide, and tantalum oxide. Diameter: about 1 to 500 nm) can be used.

This oxide semiconductor porous film 4 is composed of a colloid liquid or a dispersion liquid in which the metal oxide fine particles are dispersed, such as screen print, ink jet print, roll coat, doctor coat,
For example, it can be obtained by baking after applying to the surface of the barrier layer 3 by applying means such as spin coating or spray coating. However, since the firing temperature here is 600 ° C. or less, preferably in the range of 350 ° C. to 500 ° C., when the substrate is a resin sheet, it can be fired in a low temperature range of 100 to 150 ° C. instead. Using metal oxide paste,
It is preferable to prevent thermal deformation of the substrate by using a baking method using a microwave.

In addition, in order to increase the photoelectric conversion efficiency of the battery, a known photosensitizing dye such as a pigment or a dye having an absorption wavelength in the visible light region or the infrared region is used alone for the oxide semiconductor porous film 4, Alternatively, a mixture is supported.

When the conductive film 2 and the electrolyte layer 6 are in contact with each other, the leakage current may increase and the photoelectric conversion efficiency may decrease. Therefore, it is preferable to provide the barrier layer 3 as in the above structure. As a material of the barrier layer 3, titanium oxide, an insulating polymer, or the like can be used. However, the thickness needs to be thin enough that electrons separated by charge between the photosensitizing dye and the oxide semiconductor porous film can pass through the barrier layer. Specifically 10-50
The thickness is 0 nm, preferably 50 to 200 nm. The barrier layer 3 can be formed using a sol-gel method, a sputtering method, a vacuum deposition method, a spin coating method, or the like.

The configuration of the electrolyte layer 6 is not particularly limited, and can be a configuration as a known electrolyte layer. For example, it is good also as a structure only of electrolyte solution, and good also as a structure which hold | maintained electrolyte solution to the well-known porous support body. Moreover, it is good also as a structure of a solid electrolyte layer, and good also as a structure of an inorganic or organic hole transport layer.

The electrolytic solution is generated by dissolving an electrolyte in a solvent. The electrolyte is not particularly limited as long as a pair of redox constituents composed of an oxidant and a reductant is contained in the solvent.
For example, a redox-based constituent material in which the oxidant and the reductant have the same charge can be used. Here, the redox-based constituent material means a pair of substances that reversibly exist in the form of an oxidant and a reductant in the redox reaction, and examples thereof include chlorine compound-chlorine, iodine compound-iodine,
Bromine compound-bromine, thallium ion (III)-thallium ion (I), mercury ion (II)-mercury ion (I), ruthenium ion (III)-ruthenium ion (II), copper ion (II)-copper ion ( I)
, Iron ion (III) -iron ion (II), vanadium ion (III) -vanadium ion (II), manganate ion-permanganate ion, ferricyanide-ferrocyanide, quinone-hydroquinone, fumarate-succin An acid etc. are mentioned.

As the solvent that dissolves the electrolyte, a compound that can dissolve the redox constituents and has excellent ion conductivity is preferable. Either an aqueous solvent or an organic solvent can be used, but an organic solvent is preferred from the aspect of stabilizing the oxidation-reduction component. For example, carbonate compounds such as dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, propylene carbonate, ester compounds such as methyl acetate, methyl propionate, gamma-butyrolactone, diethyl ether, 1,2-dimethoxyethane, 1, Ether compounds such as 3-dioxosilane, tetrahydrofuran and 2-methyl-tetrahydrafuran, heterocyclic compounds such as 3-methyl-2-oxazodilinone and 2-methylpyrrolidone, nitrile compounds such as acetonitrile, methoxyacetonitrile and propionitrile, sulfolane And aprotic polar compounds such as didimethyl sulfoxide and dimethylformamide. Each of these can be used alone,
Two or more types can be mixed and used.

As the material of the catalyst layer 7, a material that exhibits a catalytic action for the redox reaction of the redox constituents in the electrolyte, such as platinum or carbon, can be used. The catalyst layer 7 can be formed by a known method such as a vapor deposition method, a sputtering method, a chemical vapor deposition method (CVD method), a coating method, or a sol-gel method. Note that only the catalyst layer 7 may be provided without providing the conductive film 8.

The phosphor layer 10 is a substrate in which a fluorescent material is dispersed. The fluorescent material may be an inorganic material or an organic material, but by dispersing the fluorescent material, a material that can absorb light in a wavelength range of 350 nm or less and emit light in a wavelength range of more than 350 nm is used. It is preferable to select. In general, in a transparent substrate made of glass, light in a wavelength region of 350 nm or less is easily subjected to transmission inhibition. Therefore, when the wavelength of the incident light is shifted to a wavelength region longer than 350 nm by the phosphor layer including such a fluorescent material, the light use efficiency in the solar cell can be improved.

As the fluorescent material, for example, Lumogen F violet 570 (trademark) or Lumogen F blue 65 manufactured by BASF Japan, whose main material is naphthalimide.
0 (trademark) or the like can be used.

It is also preferable to select a material excellent in weather resistance or a material capable of absorbing light in a wavelength region with a low quantum efficiency of the sensitizing dye and emitting light in a wavelength region with a higher quantum efficiency as the fluorescent material.

It is essential to use a light-transmitting material for the substrate. Further, as the material, it is preferable to select a material exhibiting an absorption wavelength region different from the absorption wavelength region of the fluorescent material dispersed in the substrate from the aspect of increasing the fluorescence intensity. Specific examples of the material include glass plates and resin sheets such as polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyethylene sulfide, and polyimide. Moreover, as a shape of a base | substrate, it is good also as a shape with high regularity like a plate shape, and it is good also as a shape with high flexibility, such as a film shape.

The phosphor layer in which the fluorescent material is dispersed is prepared, for example, by mixing the fluorescent material with a known solvent or dispersant in a substrate material such as resin or glass in a liquid phase and then curing the substrate material. Also good.

The main surface on the intermediate layer side of the phosphor layer is provided with a fine concavo-convex structure, the arithmetic mean roughness of the main surface is Ra (as defined in JIS B0601), the refractive index of the phosphor layer is n ₁ , When the refractive index of the intermediate layer is n ₂ , at least one of the following a) and b) is established, and preferably the following a)
More preferably, both a) and b) below are satisfied.
a) 2 nm ≦ Ra ≦ 1 μm and n ₁ −0.2 ≦ n ₂
b) 40 nm ≦ Ra ≦ 1 μm and n ₁ −0.5 ≦ n ₂

The upper limit of Ra is preferably 600 nm or less, and more preferably 200 nm or less.

The range of Ra is 40 nm or more and 60 when the relational expression n ₁ −0.2 ≦ n ₂ is satisfied.
It is preferably 0 nm or less, and more preferably 40 nm or more and 200 nm or less.

Thus, depending on the roughness of the main surface of the phosphor layer on the intermediate layer side, the relationship between the refractive index of the intermediate layer interposed between the transparent substrate and the phosphor layer and the refractive index of the phosphor layer is If controlled, total reflection of incident light accompanying wavelength conversion by the phosphor can be reduced.

In order to form the concavo-convex structure, for example, the main surface of the phosphor layer on the intermediate layer side is processed with a laser, ground with a file or a knife, etched with a solvent or reactive plasma, or heated. After the softening, a mold having a predetermined uneven shape may be pressed. In addition, a concavo-convex structure may be formed together with the production of the phosphor layer. For example, a mold having a predetermined concavo-convex shape may be used as a mold used for rolling a resin or curing a glass.

The intermediate layer 11 may be a solid layer, a liquid layer, or a gas layer. As the material for the intermediate layer, a material having higher light transmittance is preferable. Examples of the material for the liquid layer include ethanol,
Silicone oil, glycerin and the like can be used. As a material for the gas layer, for example, air or a known inert gas can be used. As a material of the solid layer, for example,
Known adhesives and pressure-sensitive adhesives can be used. When the form of the intermediate layer is a solid layer or a liquid layer from the side of increasing the transmittance of incident light into the solar cell, it is preferable to form the layer so that no bubbles remain in the layer.

When the form of the intermediate layer is a liquid layer or a gas layer, it is desirable to surround the periphery of the intermediate layer using a sealing member made of a known material to enhance its airtightness. When the form of the intermediate layer is a solid layer, a phosphor layer may be affixed on a transparent substrate using a similar sealing member, but the adhesiveness of the solid layer itself can be increased without providing a sealing member. It may be used and pasted. For example, the aspect etc. which affix the fluorescent tape by which the intermediate | middle layer as an adhesive bond layer was provided on the inner main surface (it has predetermined arithmetic mean roughness Ra) of a fluorescent film etc. are mentioned.

The intermediate layer and the transparent substrate have n ₂ ≦ n ₃ +0.5, where n ₃ is the refractive index of the transparent substrate.
It is preferable that the relational expression is satisfied. Furthermore, it is more preferable to satisfy the relational expression of n ₂ ≦ n ₃ +0.2. In this way, when controlling the relationship between the refractive index of the intermediate layer and the refractive index of the transparent substrate,
Total reflection of incident light from the intermediate layer to the transparent substrate can be reduced.

The refractive index of each member can be adjusted by a known refractive index control method. For example, a method of mixing a plurality of materials having different refractive indexes such as a method of dispersing inorganic fine particles such as titanium oxide, zirconium oxide, and silicon oxide in a resin material can be used.

Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited thereto.

Example 1
First, a titanium oxide thin film (film thickness: 100 nm) serving as a barrier layer was formed on the surface of SnO conductive glass doped with fluorine (OTE (trademark) manufactured by Nippon Sheet Glass Co., Ltd.) using a sol-gel method. The refractive index of this glass is 1.45. Next, acetylacetone, pure water, and a surfactant (Triton X100 (trademark) manufactured by Wako Pure Chemical Industries, Ltd.) are added to a commercially available titanium dioxide powder (P25 (trademark) manufactured by Nippon Aerosil Co., Ltd., volume average primary particle size 21 nm) and kneaded. The paste prepared in this manner was applied onto the titanium oxide thin film and dried, followed by 450
The film was baked at 30 ° C. for 30 minutes to form a mesoporous titanium dioxide porous film having a film thickness of 6 μm. Subsequently, this mesoporous titanium dioxide porous membrane was immersed in an ethanol solution of 0.3 mmol / L ruthenium dye, and the photosensitizing dye was supported on the porous film to produce a photoelectrode.

In parallel with this, SnO conductive glass doped with fluorine (OTE made by Nippon Sheet Glass Co., Ltd.)
A platinum film (film thickness: 14 nm) was formed on the surface of the trademark)) by vapor deposition to produce a counter electrode. In addition, a through hole was formed as an electrolyte solution injection hole.

A polyolefin-based resin hot melt agent (Hi-Milan (trademark) manufactured by Mitsui Chemicals, Inc.) as a sealing member is disposed on the periphery of the mesoporous titanium dioxide porous membrane, and then heated to 110 ° C. to face the photoelectrode. Thermocompression bonding was performed between the electrodes.

After injecting the electrolytic solution from the electrolytic solution injection hole, the injection hole was sealed with the hot melt agent and the cover glass, and the main body of the dye-sensitized solar cell was produced. In addition, this electrolyte solution is 0
. 1M lithium iodide, 0.3M 1,2-dimethyl-3-propylimidazolium iodide, 0.05M iodine and 0.5M t-butylpyridine were dissolved in methoxyacetonitrile as a solvent.

On the SnO conductive glass on the photoelectrode side of the main body, ethanol (refractive index:
A phosphor layer was attached via 1.36) to complete a dye-sensitized solar cell. The filled ethanol was surrounded by the hot melt agent and enclosed between the phosphor layer and the glass substrate.

As the phosphor layer, a commercially available fluorescent material (Lumogen F manufactured by BASF Japan Ltd.) is used.
Violet 570 (trademark)) having a mass concentration of 200 ppm dispersed in a substrate made of polymethyl methacrylate was used. The arithmetic mean roughness (Ra) of the inner main surface of this phosphor layer is 5.7 nm, and the refractive index is 1.49. Lumogen F vi above
The olet 570 is a fluorescent material that is excited by light of 250 nm to 400 nm and emits light of 400 nm to 500 nm.

(Example 2)
This is a dye-sensitized solar cell similar to that of Example 1, except that the phosphor layer having an Ra of 54.4 nm is used.

(Example 3)
This is a dye-sensitized solar cell similar to that of Example 1, except that the phosphor layer having Ra of 553.8 nm was used.

Example 4
This is a dye-sensitized solar cell similar to that of Example 2, except that air (refractive index: 1) is filled instead of ethanol.

(Example 5)
This is a dye-sensitized solar cell similar to that of Example 3, except that air was filled instead of ethanol.

(Comparative Example 1)
The dye-sensitized solar cell is the same as that of Example 1, except that the main body of the dye-sensitized solar cell is used as it is without providing the intermediate layer and the phosphor layer.

(Comparative Example 2)
This is a dye-sensitized solar cell similar to that of Example 1, except that air was filled instead of ethanol.

About each said battery, the short circuit current was investigated as follows.
(Measurement of short circuit current)
From light emitted from a xenon lamp (SX-UI1501XQ manufactured by USHIO INC.)
Using a spectroscope (MC-10N manufactured by Tree Applied Chemical Co., Ltd.), light having a wavelength of 290 nm was dispersed and used as test light (1 mW / cm ² ). While irradiating the test light from the photoelectrode side of the solar cell, the current flowing when the voltage of 0 V was applied between the photoelectrode and the counter electrode was measured with an ammeter (R8340A manufactured by Advantest Corporation) to obtain a short-circuit current.

  The short circuit currents of Examples 1 to 5 and Comparative Examples 1 and 2 are summarized in Table 1 below.

As shown in Table 1, in each of Examples 1 to 5, a short-circuit current value of 1.77 μA or more was obtained. Especially, in Examples 1-3, the high short circuit current value of 2.83 microamperes or more was obtained.
In particular, in Example 2, a short-circuit current value as high as 3.19 μA was obtained. On the other hand, Comparative Example 1
In each case, only a short-circuit current value of 1.69 μA or less was obtained.

Here, from the comparison between Examples 1 to 5 and Comparative Example 1, a phosphor layer having a main surface on the intermediate layer side (hereinafter referred to as an inner main surface) in a predetermined Ra range is interposed through the intermediate layer, It has been found that the short-circuit current value of the dye-sensitized solar cell can be improved by providing a predetermined refractive index relationship on the photoelectrode side of the solar cell.

On the other hand, from comparison between Examples 1 to 5 and Comparative Example 2, even if the phosphor layer is provided via the intermediate layer, Ra on the inner main surface of the phosphor layer is 5.7 nm, and the phosphor layer When the difference (n ₁ −n ₂ ) of the refractive index (n ₂ ) of the intermediate layer with respect to the refractive index (n ₁ ) is 0.49, it was found that the effect of improving the short-circuit current value cannot be obtained. .

Further, from the comparison between Example 1 and Comparative Example 2, when n ₁ −n ₂ is 0.13 even though Ra of the inner main surface of the phosphor layer matches 5.7 nm, n It was found that the short circuit current value was improved by 1.37 μA compared to the case where ₁₋ n ₂ was 0.49.

Further, from comparison between Example 4 and Comparative Example 2, even when n ₁ −n ₂ is equal to 0.49, when the Ra of the inner main surface of the phosphor layer is 54.4 nm, It was found that the short-circuit current value was improved by 0.2 μA compared to the case where Ra was 5.7 nm.

Further, from the comparison between Examples 2 and 4, when Ra of the inner main surface of the phosphor layer is 54.4nm, when n ₁ -n ₂ is a 0.13, n ₁ -n Compared to the case where ₂ is 0.49,
It was found that the short circuit current value was improved by 1.42 μA. Further, from the comparison between Example 3 and Example 5, when Ra of the inner main surface of the phosphor layer is 553.8nm, when n ₁ -n ₂ is a 0.13, n ₁ -n It was found that the short-circuit current value was improved by 1.42 μA compared with the case where ₂ was 0.49.

Further, from comparison between Example 1 or 3 and Example 2, when n ₁ -n ₂ is 0.13, when Ra of the inner main surface of the phosphor layer is 54.4 nm, the Ra Is 5.7 nm or 55
It was found that the short-circuit current value was further improved as compared with the case of 3.8 nm.

The reason why the short-circuit current was as low as 1.69 μA in Comparative Example 1 was that part of the test light was absorbed by the transparent substrate, and the absolute amount of light reaching the photosensitizing dye inside the porous film was reduced. it is conceivable that. In addition, the reason why the short-circuit current was as low as 1.53 μA in Comparative Example 2 is that n ₁ −n ₂ is 0.49, so that the total reflection angle at the interface between the phosphor layer and the intermediate layer is narrow, and Ra is Even if the inner main surface of the phosphor layer is roughened at about 5.7 nm, the incident angle cannot be controlled until the total reflectance of incident light is sufficiently lowered.

In the above embodiment, when the Ra of the inner main surface of the phosphor layer is in the range of 5.7 nm to 553.8 nm and n ₁ −n ₂ is 0.13 (0.1 ≦ n ₁ −n). ₂ ≦ 0.2), or when the Ra is in the range of 54.4 nm to 553.8 nm and n ₁ −n ₂ is 0.49 (0
. 4 ≦ n ₁ −n ₂ ≦ 0.5), but it has been confirmed that an excellent effect of improving the short-circuit current can be obtained as long as at least one of the following a) and b) is established.
a) 2 nm ≦ Ra ≦ 1 μm of the inner main surface of the phosphor layer, and n ₁ −0.2 ≦ n ₂
b) 40 nm ≦ Ra of inner main surface of phosphor layer ≦ 1 μm and n ₁ −0.5 ≦ n ₂

Furthermore, it has been confirmed that when the Ra of the inner main surface of the phosphor layer is 600 nm or less, preferably 200 nm or less, a further excellent short-circuit current improvement effect can be obtained. N ₁ −0
. When the relational expression 2 ≦ n ₂ is satisfied, Ra of the inner main surface of the phosphor layer is 40 nm or more and 600
It has been confirmed that when the thickness is in the range of nm or less, more preferably in the range of 40 nm or more and 200 nm or less, a further excellent short-circuit current improvement effect can be obtained.

The present invention can reduce the total reflection of incident light accompanying the wavelength conversion by the phosphor while utilizing the wavelength controllability by the phosphor, thereby improving the light utilization efficiency of the dye-sensitized solar cell. It can also be applied to.

It is sectional drawing which shows an example of the dye-sensitized solar cell of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Conductive film 3 Barrier layer 4 Oxide semiconductor porous film 5 Photoelectrode 6 Electrolyte 7 Catalyst layer 8 Conductive film 9 Substrate 10 Phosphor layer 11 Intermediate layer 12 Counter electrode 13 Main body 14 Dye-sensitized solar cell

Claims (9)

A dye-sensitized solar cell having a transparent substrate, a phosphor layer provided on the light-receiving surface side of the transparent substrate, and an intermediate layer provided between the transparent substrate and the phosphor layer,
The arithmetic mean roughness of the main surface of the phosphor layer on the intermediate layer side is Ra, and the refractive index of the phosphor layer is n.
_1. A dye-sensitized solar cell in which at least one of the following a) and b) is established, where n ₂ is a refractive index of the intermediate layer.
a) 2 nm ≦ Ra ≦ 1 μm and n ₁ −0.2 ≦ n ₂
b) 40 nm ≦ Ra ≦ 1 μm and n ₁ −0.5 ≦ n ₂ The dye-sensitized solar cell according to claim 1, wherein the phosphor layer absorbs light of 350 nm or less and emits light of 350 nm or more. The dye-sensitized solar cell according to claim 2, wherein the transparent substrate is made of a material that absorbs light of 350 nm or less.   The dye-sensitized solar cell according to claim 3, wherein a material of the transparent substrate is glass.   The dye-sensitized solar cell according to claim 1, wherein Ra is in a range of 600 nm or less.   The dye-sensitized solar cell according to claim 1, wherein Ra is in a range of 200 nm or less. In the above a) and b), n ₂ ≦ n ₃ +0.5, where n ₃ is the refractive index of the transparent substrate.
The dye-sensitized solar cell according to claim 1, wherein:   The dye-sensitized solar cell according to claim 1, wherein both a) and b) are established. A method for producing a dye-sensitized solar cell, comprising a step of providing a phosphor layer via an intermediate layer on the light-receiving surface side of a transparent substrate,
The arithmetic mean roughness of the main surface of the phosphor layer on the intermediate layer side is Ra, and the refractive index of the phosphor layer is n.
_{1. A} method for producing a dye-sensitized solar cell in which at least one of the following a) and b) is established, where n ₂ is a refractive index of the intermediate layer.
a) 2 nm ≦ Ra ≦ 1 μm and n ₁ −0.2 ≦ n ₂
b) 40 nm ≦ Ra ≦ 1 μm and n ₁ −0.5 ≦ n ₂

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