JPWO2015129608A1 - Porous light reflecting insulating layer paste, porous light reflecting insulating layer, and dye-sensitized solar cell - Google Patents

Abstract

The surface of rutile titanium oxide particles having a volume median diameter (D50) of 100 nm or more and 1000 nm or less is coated with one or more coating materials selected from silicon compounds, magnesium compounds, aluminum compounds, zirconium compounds, and calcium compounds. Particles (A) and a metal oxide particle (B) having a volume median diameter (D50) of 1 nm or more and 30 nm or less, and a mass ratio of the particles (B) to the particles (A) [ The paste for porous light-reflective insulating layers whose particle (B) / particle (A)] is 5 / 95-40 / 60.

Description

  The present invention relates to a porous light reflective insulating layer paste used for forming a porous light reflective insulating layer in a dye-sensitized solar cell, a porous light reflective insulating layer and a dye-sensitized solar cell using the same.

In recent years, research on power generation systems using sustainable energy such as solar energy, geothermal energy, and wind energy has been conducted, and among these, dye-sensitized solar cells are attracting attention as efficient power generation systems. .
As a module of a dye-sensitized solar cell, for example, a porous light reflecting layer, a porous insulating layer is formed on a porous semiconductor layer (power generation layer) obtained by sintering semiconductor fine particles such as titanium oxide and zinc oxide. Patent Document 1 discloses a structure in which conductive layers (counter electrodes) are sequentially stacked.
The porous light reflecting layer is a layer for effectively using light by reflecting incident light transmitted through the porous semiconductor layer toward the porous semiconductor layer. The thing using the titanium oxide particle which is a rate material is disclosed.
The porous insulating layer is provided as a spacer for separating the porous semiconductor layer (power generation layer) and the conductive layer. Patent Documents 2 to 4 include insulating particles such as zirconium oxide and silicon oxide, And those using rutile titanium oxide particles are disclosed.

JP 2003-142171 A JP 2008-16351 A International Publication No. 2010/044445 Japanese Patent Laid-Open No. 2004-127849

However, when the porous light reflecting layer and the porous insulating layer are individually provided as in Patent Document 3, the distance between the conductive layer (counter electrode) and the porous semiconductor layer becomes long, so that the diffusion resistance of the electrolyte is large. Thus, there is a problem that the photoelectric conversion efficiency is lowered.
On the other hand, a porous light-reflective insulating layer having both light reflectivity and insulation was formed using rutile-type titanium oxide particles having light reflectivity and insulation properties as disclosed in Patent Document 4 in order to solve the above problem. In this case, due to the nature of the material, sintering cannot be performed at a high temperature, so that the adhesion between the porous light reflecting insulating layer and the porous semiconductor layer is lowered. Therefore, the porous light reflection insulating layer is easily peeled off from the porous semiconductor layer, resulting in a problem that the photoelectric conversion efficiency is lowered.

  The present invention has been made in view of the above-described problems, and has high adhesion to a porous semiconductor layer and can form a porous light reflecting insulating layer that contributes to improvement of photoelectric conversion efficiency. A reflective insulating layer paste, a porous light reflecting insulating layer formed using the same, and a dye-sensitized solar cell including the porous light reflecting insulating layer are provided.

  As a result of intensive studies to solve the above problems, the present inventors have found that a rutile-type titanium oxide having a specific particle size is surface-treated with a silicon compound, an aluminum compound, or the like, When used in combination with metal oxide particles having a particle size, the porous light can form a porous light-reflective insulating layer that has high adhesion to the porous semiconductor layer and contributes to improvement in photoelectric conversion efficiency. The present inventors have found that a paste for a reflective insulating layer can be obtained and completed the present invention.

That is, this invention makes the following a summary.
[1] One or more coatings selected from silicon compounds, magnesium compounds, aluminum compounds, zirconium compounds, and calcium compounds on the surface of rutile-type titanium oxide particles having a volume median diameter (D50) of 100 nm or more and 1000 nm or less Particles (A) coated with a material and metal oxide particles (B) having a volume median diameter (D50) of 1 nm or more and 30 nm or less, and the particles (B) with respect to the particles (A) The paste for porous light-reflective insulating layers whose mass ratio [particle (B) / particle (A)] is 5 / 95-40 / 60.
[2] The porous light reflective insulating layer paste according to [1], wherein the coating amount of the coating material in the particles (A) is 1% by mass or more and 30% by mass or less.
[3] The porous light reflective insulating layer paste according to [1] or [2], wherein the particles (B) are anatase-type titanium oxide particles.
[4] A porous light reflective insulating layer formed using the porous light reflective insulating layer paste according to any one of [1] to [3].
[5] A dye-sensitized solar cell provided with the porous light reflecting insulating layer according to [4].

  ADVANTAGE OF THE INVENTION According to this invention, the paste for porous light reflection insulation layers which can form the porous light reflection insulation layer which has high adhesiveness with a porous semiconductor layer and contributes to the improvement of photoelectric conversion efficiency, and using this The formed porous light reflecting insulating layer and a dye-sensitized solar cell including the porous light reflecting insulating layer can be provided.

It is a schematic block diagram which shows an example of the dye-sensitized solar cell of this invention.

[Paste for porous light-reflective insulating layer]
The porous light-reflective insulating layer paste of the present invention comprises a silicon compound, a magnesium compound, an aluminum compound, a zirconium compound, and a surface of rutile titanium oxide particles having a volume median diameter (D50) of 100 nm to 1000 nm. Particles (A) coated with one or more coating materials selected from calcium compounds, and metal oxide particles (B) having a volume median diameter (D50) of 1 nm or more and 30 nm or less, the particles The mass ratio [particle (B) / particle (A)] of the particle (B) to (A) is 5/95 to 40/60.
In the present specification, the “volume median diameter (D50)” refers to a particle size at which the cumulative volume frequency calculated by the volume fraction is 50% calculated from the smaller particle size. The measuring method is as described in the examples.
In addition, when the paste for porous light reflection insulation layers of the present invention is measured with, for example, a laser diffraction type particle size measuring device (manufactured by Horiba, Ltd., model number “LA-750”), the volume median diameter (D50) is Two peaks are observed, a distribution having a peak at 1 nm or more and 30 nm or less and a distribution having a volume median diameter (D50) having a peak at 100 nm or more and 1000 nm or less.

<Particle (A)>
Particle (A) is a kind selected from silicon compounds, magnesium compounds, aluminum compounds, zirconium compounds, and calcium compounds on the surface of rutile titanium oxide particles having a volume median diameter (D50) of 100 nm or more and 1000 nm or less. It is coated with the above coating material.

[Rutyl-type titanium oxide particles]
The volume median diameter (D50) of the rutile-type titanium oxide particles is 100 nm or more and 1000 nm or less. When the volume median diameter (D50) is 100 nm or more, light can be sufficiently reflected. When the volume median diameter (D50) is 1000 nm or less, the insulating property is improved. Leakage current to the conductive layer is suppressed.
The volume median diameter (D50) of the rutile-type titanium oxide particles is preferably 110 nm or more and 950 nm or less, more preferably 150 nm or more and 920 nm or less, and more preferably 150 nm or more and 900 nm or less from the viewpoint of improving light reflectivity and insulation. More preferably, it is more preferably 200 nm or more and 800 nm or less, and particularly preferably 250 nm or more and 700 nm or less.
The volume median diameter (D50) of the rutile titanium oxide particles and the volume median diameter (D50) of the particles (A) coated with the coating material can be regarded as substantially the same.

The average primary particle diameter of the rutile-type titanium oxide particles is preferably 100 nm or more and 1000 nm or less, preferably 110 nm or more and 950 nm or less, more preferably 150 nm or more and 920 nm or less, more preferably 150 nm, from the viewpoint of improving light reflectivity and insulation. As mentioned above, 900 nm or less is still more preferable, 200 nm or more and 800 nm or less are still more preferable, 250 nm or more and 700 nm or less are especially preferable.
The volume median diameter (D50) of the rutile titanium oxide particles and the average primary particle diameter of the rutile titanium oxide particles can be regarded as substantially the same.
In this specification, the average primary particle diameter of rutile-type titanium oxide particles is a value obtained by measuring 100 major axes of particles with a scanning electron microscope and averaging them.

(Coating material)
Examples of the coating material for coating the rutile-type titanium oxide particles include one or more selected from silicon compounds, magnesium compounds, aluminum compounds, zirconium compounds, and calcium compounds. The reason why the photoelectric conversion efficiency of the porous semiconductor layer (power generation layer) is improved by surface treatment of rutile titanium oxide with the coating material is not clear, but rutile titanium oxide particles and particles (B) It is presumed that this is due to the fact that they are not in direct contact.

Specific examples of the coating material include one or more selected from silica, magnesia, alumina, zirconia, and calcia.
Among the coating materials, a silicon compound and an aluminum compound are preferable, and a combination of a silicon compound and an aluminum compound is more preferable. More specifically, silica and alumina are preferable, and the combined use of silica and alumina is more preferable.

As a method for coating the surface of rutile-type titanium oxide particles with a coating material, for example, a dispersion containing rutile-type titanium oxide particles, a sodium silicate solution, a sodium aluminate solution and water is stirred, and this dispersion is neutralized with sulfuric acid. A method of coating by heating at 50 ° C. or more and 70 ° C. or less for 1 hour or more and 5 hours or less after summing is mentioned.
In the present invention, the thickness of the coating material formed on the surface of the rutile type titanium oxide particles is preferably 3 nm or more and 25 nm or less from the viewpoint of preventing the contact between the rutile type titanium oxide particles and the particles (B). As mentioned above, 20 nm or less is more preferable, and 8 nm or more and 15 nm or less are still more preferable.
The covering material is preferably coated on the entire surface of the rutile titanium oxide particles, but may be partially coated.

[Coating amount]
The coating amount of the coating material in the particles (A) is preferably 1% by mass or more and 30% by mass or less, more preferably 1.5% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 15% by mass or less. Further preferred. When the coating amount of the coating material is within the above range, light reflectivity and insulating properties can be compatible at a high level, so that the photoelectric conversion efficiency of the porous semiconductor layer (power generation layer) is improved. In addition, a coating amount shows the ratio of the coating | covering material contained in the whole quantity of particle | grains (A). The coating amount can be determined by dividing the mass of the coating material contained in the total amount of the particles (A) by the total mass of the particles (A).
In addition, the mass of particle | grains and a coating | covering material can be calculated | required by converting the value measured by ICP emission analysis.

[Content of Particle (A)]
The content of the particles (A) in the porous light-reflective insulating layer paste is preferably 10% by mass or more and 40% by mass or less, and preferably 15% by mass or more and 35% by mass or less from the viewpoint of improving the photoelectric conversion efficiency. Is more preferable, 20 mass% or more and 30 mass% or less is still more preferable, and 23 mass% or more and 30 mass% or less is still more preferable.

<Particle (B)>
The particles (B) are metal oxide particles having a volume median diameter (D50) of 1 nm or more and 30 nm or less.
When the volume median diameter (D50) of the particles (B) is 1 nm or more, the particles are less likely to aggregate with each other, so that the handleability is improved. Further, when the volume median diameter (D50) is 30 nm or less, the interval between the particles is narrowed, so that sufficient insulation can be ensured.
The volume median diameter (D50) of the particles (B) is preferably 5 nm or more and 28 nm or less, more preferably 10 nm or more and 26 nm or less, further preferably 12 nm or more and 24 nm or less, and 15 nm, from the viewpoints of handleability and adhesion. As mentioned above, 22 nm or less is still more preferable.
The average primary particle size of the particles (B) is preferably 1 nm or more and 30 nm or less, more preferably 5 nm or more and 28 nm or less, further preferably 10 nm or more and 26 nm or less, more preferably 12 nm or more and 24 nm or less, and even more preferably 15 nm. As mentioned above, 22 nm or less is especially preferable.
The volume median diameter (D50) of the particles (B) and the average primary particle diameter of the particles (B) can be regarded as substantially the same.

The particle (B) is not particularly limited as long as it is a metal oxide particle having low electron conductivity. For example, one or more oxides selected from titanium, silicon, aluminum, zirconium, calcium, and magnesium, or these A composite oxide is mentioned. Among these, at least one selected from titanium oxide and silica is more preferable, and anatase-type titanium oxide is more preferable.
In addition, it is not preferable to use a particle (B) whose surface is covered with a coating material such as the particle (A) because the adhesion to the porous semiconductor layer is lowered.

<Mass ratio of particles (B) to particles (A)>
The mass ratio [particle (B) / particle (A)] of the particle (B) to the particle (A) in the porous light-reflective insulating layer paste is 5/95 to 40/60. When the mass ratio is within the above range, light reflectivity and insulation are improved, and adhesiveness with the porous semiconductor layer is improved, so that the photoelectric conversion efficiency of the porous semiconductor layer (power generation layer) is improved.
The mass ratio [particle (B) / particle (A)] is preferably 7/93 to 38/62, from the viewpoint of improving light reflectivity, insulation, and photoelectric conversion efficiency of the porous semiconductor layer, and 9/91. ~ 32/68 is more preferable, 9/91 to 29/71 is still more preferable, and 9/91 to 25/75 is still more preferable.

<Optional component>
The porous light reflective insulating layer paste of the present invention preferably uses a dispersion medium from the viewpoint of viscosity adjustment and the like.
Although there is no restriction | limiting in particular in a dispersion medium, It is preferable to use diols, such as hexylene glycol and propylene glycol, and high boiling point organic dispersion media, such as a terpineol.
The amount of the dispersion medium with respect to 100 parts by mass in total of the particles (A) and the particles (B) is 1 part by mass or more from the viewpoint of preventing a decrease in the viscosity of the paste for porous light-reflective insulating layer and a decrease in printability 500 parts by mass or less, preferably 50 parts by mass or more and 250 parts by mass or less, more preferably 150 parts by mass or more and 220 parts by mass or less.

The porous light reflective insulating layer paste of the present invention may contain a cellulose resin such as ethyl cellulose, an acrylic resin, or the like from the viewpoint of adjusting the viscosity and the film thickness.
Furthermore, generally used additives such as a leveling agent, a chelating agent, a surfactant, a titanium coupling agent, and a thickener may be appropriately added.
Examples of the leveling agent include water, ethylene glycol, polyethylene glycol, and glycerin.
Examples of chelating agents include acetylacetone, benzylacetone, and acetic acid.
Examples of the surfactant include polyethylene glycol.
Examples of the thickener include methyl cellulose and ethyl cellulose.

[Viscosity of paste for porous light reflection insulating layer]
The viscosity of the paste for a porous light-reflective insulating layer measured using a dynamic viscoelasticity test apparatus under conditions of a temperature of 25 ° C. and a shear rate of 1 s ⁻¹ is preferably 10 Pa · s or more and 1000 Pa · s or less, and 100 Pa · s. As described above, 1000 Pa · s or less is more preferable.

<Method for Producing Porous Light Reflecting Insulating Layer Paste>
The porous light-reflective insulating layer paste can be produced by appropriately mixing the particles (A), the particles (B), and, if necessary, optional components such as a dispersion medium.
More specifically, it can be obtained by mixing particles (A), particles (B), a high-boiling organic dispersion medium such as hexylene glycol and terpineol, and a thickener such as ethyl cellulose.

[Porous light reflective insulating layer]
The porous light reflective insulating layer of the present invention is formed using the porous light reflective insulating layer paste of the present invention.
Although there is no restriction | limiting in particular in the thickness of a porous light reflection insulation layer, From a viewpoint of insulation efficiency, 5 micrometers or more and 50 micrometers or less are preferable, 5 micrometers or more and 40 micrometers or less are more preferable, 5 micrometers or more and 30 micrometers or less are still more preferable, 5 micrometers or more 20 μm or less is still more preferable, and 5 μm or more and 10 μm or less is particularly preferable.

In the present invention, the reflectance of light having a wavelength of 550 nm of the porous light reflecting insulating layer is preferably 60% or more, more preferably 70% or more, and 75% from the viewpoint of efficiently reflecting light to the porous semiconductor layer. The above is more preferable.
From the viewpoint of use as an insulating layer, the resistance value of the porous light reflecting insulating layer is preferably 1 kΩ or more, more preferably 100 kΩ or more, and further preferably 10 MΩ or more.

  When the porous light reflection insulating layer is observed with a scanning electron microscope, it is observed that the particles (A) and the particles (B) are mixed. That is, when the porous light-reflective insulating layer is observed, large particles (A) having an average primary particle diameter of 100 nm to 1000 nm and small particles (B) having an average primary particle diameter of 1 nm to 70 nm are observed. In many cases, the particle (B) grows by firing and becomes larger than the particle size used in the paste.

<Method for producing porous light-reflective insulating layer>
The method for producing the porous light-reflective insulating layer of the present invention is not particularly limited. For example, the porous light-reflective insulating layer paste of the present invention is formed by a known method to form a substrate (for example, a porous semiconductor layer (power generation layer) It can be manufactured by firing on a substrate).
Examples of the method for applying the paste for the porous light-reflective insulating layer of the present invention on the substrate include screen printing methods and ink jet methods. Among these, the screen printing method is preferable from the viewpoint of facilitating thickening and suppressing the manufacturing cost.
Firing is preferably performed in the air or in an inert gas atmosphere at 50 ° C. or higher and 800 ° C. or lower, 10 seconds or longer, and 4 hours or shorter. Firing may be performed only once at a constant temperature, or may be performed twice or more at different temperatures. It is preferable that the porous light reflecting insulating layer paste is applied and then dried and fired.

[Dye-sensitized solar cell]
The dye-sensitized solar cell of the present invention includes the porous light-reflective insulating layer of the present invention, and the porous light-reflective insulating layer is provided between the porous semiconductor layer and the conductive layer (counter electrode). Is.
Since the porous light reflecting insulating layer of the present invention has both functions of the porous light reflecting layer and the porous insulating layer, the porous light reflecting layer and the porous insulating layer are separately provided. Since the distance between the porous semiconductor layer and the conductive layer (counter electrode) can be shortened compared to the case, the photoelectric conversion efficiency can be improved.

  An example of the dye-sensitized solar cell (series module type) of the present invention is shown in FIG. The dye-sensitized solar cell 10 of this embodiment includes a transparent substrate 1 having a transparent conductive film 2, a conductive layer (counter electrode) 5 provided to face the transparent conductive film 2, and the transparent conductive film. A porous semiconductor layer 7 and a porous light reflecting insulating layer 6 are provided between the conductive layer 5 and the conductive layer 5 in this order from the transparent conductive film 2 side, and the electrolyte 4 is sealed in the module by the sealing material 3. Has been. The conductive layer 5 is in direct contact with the adjacent transparent conductive film 2. A catalyst layer (not shown) may be provided between the porous light reflective insulating layer 6 and the conductive layer 5.

Although there is no restriction | limiting in the porous semiconductor layer 7 and the conductive layer 5 which comprise the said dye-sensitized solar cell 10, Specifically, the following structures are employable.
<Porous semiconductor layer>
The porous semiconductor layer 7 is composed of a semiconductor, and the form thereof may be a particulate form or a film form, but is preferably a film form. As a material constituting the porous semiconductor layer 7, one or more kinds of known semiconductor particles such as titanium oxide and zinc oxide can be used. In these, a titanium oxide is preferable from the point of photoelectric conversion efficiency, and anatase type titanium oxide is more preferable.
As a particle size of the semiconductor particles, the average primary particle size is preferably 1 nm or more and 500 nm or less, more preferably 1 nm or more and 30 nm or less.

Although there is no restriction | limiting in particular in the method of producing the porous semiconductor layer 7, It can obtain by producing the paste for porous semiconductor layers, apply | coating on a board | substrate, and baking it.
The method for obtaining the porous semiconductor layer paste can be obtained by appropriately mixing the semiconductor particles with a solvent, a thickener or the like, similarly to the method for obtaining the porous light reflecting insulating layer paste.
As a method for forming the porous semiconductor layer 7 on the substrate, a known method can be adopted as in the method for producing the porous light reflecting insulating layer. Specifically, a method of applying a paste containing semiconductor particles on a substrate by a screen printing method, an ink jet method, or the like, and then firing the substrate can be used.

In order to improve the photoelectric conversion efficiency, it is necessary to adsorb more dye, which will be described later, to the porous semiconductor layer 7. For this reason, the membrane-like porous semiconductor layer 7 preferably has a large specific surface area, and is preferably 10 m ² / g or more and 200 m ² / g or less, for example. In addition, the specific surface area shown in this specification is a value measured by the BET adsorption method.
The drying and firing of the porous semiconductor layer 7 can be performed by appropriately adjusting conditions such as temperature, time, atmosphere, and the like depending on the substrate to be used and the type of semiconductor particles to be contained. As a specific method, a method of firing at 50 ° C. or higher and 800 ° C. or lower for 10 seconds or longer and 4 hours or shorter in the air or an inert gas atmosphere can be given.

(Dye)
As a dye as a photosensitizer to be adsorbed on the porous semiconductor layer 7, from the viewpoint of strongly adsorbing the dye on the porous semiconductor layer 7, a carboxylic acid group, a carboxylic acid anhydride group, a sulfonic acid group, etc. in the dye molecule A dye having an interlocking group of The interlock group refers to a group that provides an electrical bond that facilitates electron transfer between the excited dye and the conduction band of the porous semiconductor layer.
Examples of these dyes containing an interlock group include ruthenium bipyridine dyes, azo dyes, quinone dyes, quinone imine dyes, squarylium dyes, cyanine dyes, merocyanine dyes, porphyrin dyes, and phthalocyanine dyes. , One or more selected from indigo dyes and naphthalocyanine dyes are preferred.

As a method for adsorbing the dye to the porous semiconductor layer 7, a solution in which the porous semiconductor layer 7 or the like is formed on the conductive substrate (transparent conductive film 2) is dissolved in the dye (solution for dye adsorption). The method of immersing in is mentioned.
Solvents for dissolving the dye include alcohols such as ethanol, ketones such as acetone, ethers such as diethyl ether and tetrahydrofuran, nitrogen compounds such as acetonitrile, halogenated aliphatic hydrocarbons such as chloroform, and fats such as hexane. Aromatic hydrocarbons such as aromatic hydrocarbons, benzene, esters such as ethyl acetate and butyl acetate, and water. Two or more of these solvents can be used in combination.
The concentration of the dye in the solution can be appropriately adjusted depending on the kind of the dye and the solvent to be used, but a higher concentration is preferable in order to improve the adsorption function, for example, 1 × 10 ⁻⁵ mol / L or more. preferable.

<Conductive layer>
The conductive layer 5 is not particularly limited as long as it has an ability to reduce the oxide of the electrolyte and conductivity, but is selected from, for example, Pt, C, Ni, Cr, stainless steel, fluorine-doped tin oxide, and ITO. It is preferable that it contains 1 or more types. Among these, the use of Pt as the conductive layer 5 is more preferable because it becomes a catalyst conductive layer that also functions as a catalyst.

<Electrolyte (electrolyte)>
Examples of the electrolyte 4 include one or more selected from an iodine-based electrolyte, a bromine-based electrolyte, a selenium-based electrolyte, and a sulfur-based electrolyte.
It is preferable to use an electrolytic solution obtained by dissolving the electrolyte 4 and I ₂ , LiI, dimethylpropylimidazolium iodide or the like in an organic solvent such as acetonitrile, methoxyacetonitrile, propylene carbonate, ethylene carbonate, or the like.

<Method for producing dye-sensitized solar cell>
There is no restriction | limiting in particular in the manufacturing method of the dye-sensitized solar cell of this invention, It is well-known using suitably constituent materials, such as a conductive substrate, a porous semiconductor layer, a porous reflective insulating layer, and a conductive layer (counter electrode). It can be manufactured by the method.
The dye-sensitized solar cell of the present invention is not particularly limited except that the porous light-reflecting insulating layer of the present invention is used, and constituent materials used for general dye-sensitized solar cells are appropriately selected. Can be used.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention concretely, this invention is not limited by these Examples.
The volume median diameter (D50) of each particle was measured by using a laser diffraction particle size measuring machine (manufactured by Horiba, Ltd., model number “LA-750”) as a measuring device, and each particle dispersed in distilled water. Was measured.

[Example 1]
(Preparation of particles (A-1): Preparation of titanium oxide particles coated with silica and alumina)
A rutile type titanium oxide particle (manufactured by Sumitomo Osaka Cement Co., Ltd.) having a volume median diameter (D50) of 280 nm (average primary particle size is 280 nm), water, a sodium silicate solution, and a sodium aluminate solution are converted into a rutile type oxidation. Mixing was performed so that the mass ratio of titanium, silica, and alumina (rutile titanium oxide / silica / alumina) was 90/2/8 to obtain 100 g of a dispersion. Next, this dispersion was neutralized with sulfuric acid and heated at 60 ° C. for 3 hours to coat the surface of the rutile-type titanium oxide particles with silica and alumina. Particles (A-1) were obtained by filtering the heated solution.
When this particle (A-1) was observed with a transmission electron microscope (TEM: manufactured by Hitachi, Ltd., model number “H-800”), a coating film having a thickness of 10 nm was formed on the surface of the particle. .

(Preparation of porous light reflecting insulating layer paste)
Anatase-type titanium oxide particles having 27 parts by mass of the particles (A-1) and a volume median diameter (D50) of 20 nm (average primary particle diameter of 20 nm) [particles (B-1): manufactured by Sumitomo Osaka Cement Co., Ltd.] 3 100 g of the paste for the porous light-reflective insulating layer of Example 1 was prepared by mixing 10 parts by mass of ethyl cellulose, 10 parts by mass of ethyl cellulose, and 60 parts by mass of terpineol. The viscosity of this porous light-reflective insulating layer paste was measured at a temperature of 25 ° C. and a shear rate of 1 s ⁻¹ using a dynamic viscoelasticity test apparatus, and found to be 300 mPa · s.

<Preparation of dye-sensitized solar cell>
(Preparation of porous semiconductor layer)
26 parts by mass of anatase-type titanium oxide particles having an average primary particle diameter of 20 nm, 8 parts by mass of ethyl cellulose, and 66 parts by mass of terpineol were mixed to prepare 100 g of a paste for forming a porous semiconductor layer.
The obtained paste for forming a porous semiconductor layer is a substrate with a transparent conductive film having a width of 19 mm and a length of 15 mm, and the conductive film at a position of 12.5 mm from the left end is removed in the vertical direction to provide a scribe line. Centering on the central portion of the substrate, screen printing was performed so as to have a length of 5 mm, a width of 5 mm, and a film thickness of 7 μm after firing, followed by firing at 500 ° C. for 60 minutes.

(Preparation of porous light-reflective insulating layer)
Next, the porous light-reflective insulating layer paste of Example 1 is screen-printed on the porous semiconductor layer so that the center portion of the substrate is 7 mm in length, 7 mm in width, and 7 μm in thickness after baking. The porous reflective insulating layer was formed by baking at 500 ° C. for 60 minutes.

(Catalyst conductive layer production)
The catalyst conductive layer (opposite electrode) is formed by depositing platinum in a range of 7 mm to 14 mm from the left end of the substrate on which the porous reflective insulating layer is formed and 5 mm to 10 mm from the lower end so that the length is 5 mm, the width is 7 mm, and the thickness is 1 μm. Formed.
Next, this substrate was immersed in a 0.3 mM Ru metal dye (Black Dye dye, manufactured by Daisol Co.) solution for 24 hours to adsorb the dye to the porous semiconductor layer to obtain an electrode.

(Preparation of electrolyte)
With respect to acetonitrile, as a supporting electrolyte, iodine salt of 1,2-dimethyl-3-propylimidazolium is 0.6M, lithium iodide is 0.1M, iodine is 0.05M, and t-butylpyridine is 0.5M. It mixed so that electrolyte solution might be produced.

(Preparation of dye-sensitized solar cell)
Using the obtained electrode, 10 mg of the electrolytic solution was injected and sealed with a sealing material to produce a series module type dye-sensitized solar cell shown in FIG.
During the production of this dye-sensitized solar cell, the film peeling between the porous semiconductor layer and the porous light-reflecting insulating layer did not occur, and the adhesion was good.

(Evaluation of photoelectric conversion efficiency)
Using a solar simulator (manufactured by Yamashita Denso Co., Ltd.), the dye-sensitized solar cell of Example 1 was irradiated with simulated sunlight, and the IV characteristics were measured with a current-voltage measuring device (manufactured by Yamashita Denso Co., Ltd.). The photoelectric conversion efficiency was calculated | required by measuring. As a result, the photoelectric conversion efficiency was 7.3% (short-circuit current density 15.1 (A · cm ⁻¹ ), open-circuit voltage 0.70 (V), fill factor 0.69). The results are shown in Table 1.

[Example 2]
(Preparation of porous light reflecting insulating layer paste)
A porous light-reflective insulating layer paste of Example 2 was produced in the same manner as Example 1 except that 21 parts by mass of particles (A-1) and 9 parts by mass of particles (B-1) were used. The viscosity of this porous light-reflective insulating layer paste was 350 mPa · s when measured using a dynamic viscoelasticity test apparatus at a temperature of 25 ° C. and a shear rate of 1 s ⁻¹ .

A dye-sensitized solar cell of Example 2 was produced in the same manner except that the porous light reflective insulating layer paste of Example 2 was used as the porous light reflective insulating layer paste. During the production of the dye-sensitized solar cell, the film peeling between the porous semiconductor layer and the porous light-reflective insulating layer did not occur, and the adhesion was good.
As a result of measuring photoelectric conversion efficiency in the same manner as in Example 1, it was 6.7% (short-circuit current density 13.8 (A · cm ⁻¹ ), open-circuit voltage 0.71 (V), fill factor 0.68). It was. The results are shown in Table 1.

[Example 3]
(Preparation of particles (A-2): Preparation of titanium oxide particles coated with silica and alumina)
The particle (A-2) is obtained in the same manner as the particle (A-1) except that the mass ratio of rutile titanium oxide, silica and alumina (rutile titanium oxide / silica / alumina) is 75/5/20. It was.

(Preparation of porous light reflecting insulating layer paste)
The paste for porous light-reflective insulating layer of Example 3 in the same manner as in Example 1 except that 21 parts by mass of particles (A-2) and 9 parts by mass of particles (B-1) were used as particles (A). Was made. The viscosity of this porous light-reflective insulating layer paste was 350 mPa · s when measured using a dynamic viscoelasticity test apparatus at a temperature of 25 ° C. and a shear rate of 1 s ⁻¹ .

(Preparation of dye-sensitized solar cell)
A dye-sensitized solar cell of Example 3 was fabricated in the same manner as in Example 1 except that the porous light reflective insulating layer paste of Example 3 was used as the porous light reflective insulating layer paste. During the production of the dye-sensitized solar cell, the film peeling between the porous semiconductor layer and the porous light-reflective insulating layer did not occur, and the adhesion was good.
As a result of measuring photoelectric conversion efficiency in the same manner as in Example 1, it was 6.2% (short-circuit current density 12.7 (A · cm ⁻¹ ), open-circuit voltage 0.71 (V), fill factor 0.69). It was. The results are shown in Table 1.

[Example 4]
(Preparation of particles (A-3): preparation of titanium oxide particles coated with silica and alumina)
Particles similar to particles (A-1) except that the mass ratio of rutile titanium oxide, silica and alumina (rutile titanium oxide / silica / alumina) was 98.5 / 0.3 / 1.2. (A-3) was obtained.

(Preparation of porous light reflecting insulating layer paste)
For the porous light-reflective insulating layer of Example 4, except that 21 parts by mass of particles (A-3) and 9 parts by mass of particles (B-1) were used as particles (A). A paste was prepared. The viscosity of this porous light-reflective insulating layer paste was 350 mPa · s when measured using a dynamic viscoelasticity test apparatus at a temperature of 25 ° C. and a shear rate of 1 s ⁻¹ .

(Preparation of dye-sensitized solar cell)
A dye-sensitized solar cell of Example 4 was produced in the same manner as in Example 1 except that the paste for porous light reflecting insulating layer of Example 4 was used as the paste for porous light reflecting insulating layer. During the production of the dye-sensitized solar cell, the film peeling between the porous semiconductor layer and the porous light-reflective insulating layer did not occur, and the adhesion was good.
As a result of measuring the photoelectric conversion efficiency in the same manner as in Example 1, it was 7.0% (short-circuit current density 15.4 (A · cm ⁻¹ ), open-circuit voltage 0.66 (V), fill factor 0.69). It was. The results are shown in Table 1.

[Example 5]
(Preparation of particles (A-4): Preparation of titanium oxide particles coated with silica and alumina)
Particles (A-4) were the same as particles (A-4) except that rutile titanium oxide particles having a volume median diameter (D50) of 900 nm (made by Sumitomo Osaka Cement Co., Ltd.) were used as rutile titanium oxide. )

(Preparation of porous light reflecting insulating layer paste)
A porous light-reflective insulating layer paste of Example 5 was produced in the same manner as Example 1 except that the particles (A-4) were used as the particles (A). The viscosity of this porous light-reflective insulating layer paste was 250 mPa · s when measured using a dynamic viscoelasticity test apparatus at a temperature of 25 ° C. and a shear rate of 1 s ⁻¹ .

(Preparation of dye-sensitized solar cell)
A dye-sensitized solar cell of Example 5 was produced in the same manner as Example 1 except that the paste for porous light reflective insulation layer of Example 5 was used as the paste for porous light reflection insulation layer. During the production of the dye-sensitized solar cell, the film peeling between the porous semiconductor layer and the porous light-reflective insulating layer did not occur, and the adhesion was good.
The photoelectric conversion efficiency was measured in the same manner as in Example 1. As a result, it was 7.5% (short-circuit current density 16.2 (A · cm ⁻¹ ), open-circuit voltage 0.70 (V), fill factor 0.66). It was. The results are shown in Table 1.

[Example 6]
(Preparation of particles (A-5): Preparation of titanium oxide particles surface-coated with silica and alumina)
The particles (A-) were the same as the particles (A-1) except that rutile titanium oxide particles having a volume median diameter (D50) of 110 nm (made by Sumitomo Osaka Cement Co., Ltd.) were used as rutile titanium oxide particles. 5) was obtained.

(Preparation of porous light reflecting insulating layer paste)
A porous light-reflective insulating layer paste of Example 6 was produced in the same manner as Example 1 except that the particles (A-5) were used as the particles (A). The viscosity of this porous light-reflective insulating layer paste was measured at a temperature of 25 ° C. and a shear rate of 1 s ⁻¹ using a dynamic viscoelasticity test apparatus, and it was 400 mPa · s.

(Preparation of dye-sensitized solar cell)
A dye-sensitized solar cell of Example 6 was produced in the same manner except that the porous light reflective insulating layer paste of Example 6 was used as the porous light reflective insulating layer paste. During the production of the dye-sensitized solar cell, the film peeling between the porous semiconductor layer and the porous light-reflective insulating layer did not occur, and the adhesion was good.
As a result of measuring the photoelectric conversion efficiency in the same manner as in Example 1, it was 6.4% (short-circuit current density 13.1 (A · cm ⁻¹ ), open-circuit voltage 0.70 (V), fill factor 0.70). It was. The results are shown in Table 1.

[Example 7]
(Preparation of Particle (A-6): Preparation of Titanium Oxide Particles Surface-Coated with Silica)
A particle (A-6) was obtained in the same manner as the particle (A-1) except that the mass ratio of rutile titanium oxide and silica (rutile titanium oxide / silica) was 90/10. .

(Preparation of porous light reflecting insulating layer paste)
A porous light-reflective insulating layer paste of Example 7 was produced in the same manner as Example 1 except that the particles (A-6) were used as the particles (A). The viscosity of this porous light-reflective insulating layer paste was measured at a temperature of 25 ° C. and a shear rate of 1 s ⁻¹ using a dynamic viscoelasticity test apparatus, and found to be 300 mPa · s.

(Preparation of dye-sensitized solar cell)
A dye-sensitized solar cell of Example 7 was produced in the same manner as in Example 1 except that the porous light reflective insulating layer paste of Example 7 was used as the porous light reflective insulating layer paste. During the production of the dye-sensitized solar cell, the film peeling between the porous semiconductor layer and the porous light-reflective insulating layer did not occur, and the adhesion was good.
The photoelectric conversion efficiency was measured in the same manner as in Example 1. As a result, it was 7.2% (short-circuit current density 15.0 (A · cm ⁻¹ ), open-circuit voltage 0.70 (V), fill factor 0.69). It was. The results are shown in Table 1.

[Comparative Example 1]
(Preparation of porous light reflecting insulating layer paste)
Comparative Example as in Example 1 except that 29.1 parts by mass of particles (A-1) and 0.9 parts by mass of particles (B-1) were used as particles (A) and particles (B). No. 1 porous light reflecting insulating layer paste was prepared. The viscosity of this porous light-reflective insulating layer paste was measured at a temperature of 25 ° C. and a shear rate of 1 s ⁻¹ using a dynamic viscoelasticity test apparatus, and found to be 200 mPa · s.

  A dye-sensitized solar cell was prepared in the same manner except that the porous light-reflective insulating layer paste of Comparative Example 1 was used as the porous light-reflective insulating layer paste. Adhesiveness with the light-reflecting insulating layer was poor, the porous light-reflecting insulating layer was peeled off, and a dye-sensitized solar cell could not be produced. The results are shown in Table 1.

[Comparative Example 2]
(Preparation of porous light reflecting insulating layer paste)
The porous material of Comparative Example 2 was the same as Example 1 except that 6 parts by mass of particles (A-1) and 24 parts by mass of particles (B-1) were used as particles (A) and particles (B). A light reflective insulating layer paste was prepared. The viscosity of this porous light-reflective insulating layer paste was 500 mPa · s when measured using a dynamic viscoelasticity test apparatus at a temperature of 25 ° C. and a shear rate of 1 s ⁻¹ .

(Preparation of dye-sensitized solar cell)
A dye-sensitized solar cell of Comparative Example 2 was produced in the same manner as Example 1 except that the porous light reflective insulating layer paste of Comparative Example 2 was used as the porous light reflective insulating layer paste. During the production of the dye-sensitized solar cell, the film peeling between the porous semiconductor layer and the porous light-reflective insulating layer did not occur, and the adhesion was good.
As a result of measuring the photoelectric conversion efficiency in the same manner as in Example 1, it was 4.5% (short-circuit current density 12.0 (A · cm ⁻¹ ), open-circuit voltage 0.60 (V), fill factor 0.62). It was. The results are shown in Table 1.

[Comparative Example 3]
Use of rutile type titanium oxide particles (Sumitomo Osaka Cement Co., Ltd.) having a volume median diameter (D50) of 280 nm as particles (A), that is, using rutile type titanium oxide particles not coated with silica and alumina. A porous light-reflective insulating layer paste of Comparative Example 3 was produced in the same manner as in Example 1 except that it was the same. The viscosity of this porous light-reflective insulating layer paste was measured at a temperature of 25 ° C. and a shear rate of 1 s ⁻¹ using a dynamic viscoelasticity test apparatus, and found to be 300 mPa · s.

A dye-sensitized solar cell of Comparative Example 3 was produced in the same manner as Example 1 except that the porous light reflective insulating layer paste of Comparative Example 3 was used as the porous light reflective insulating layer paste. During the production of the dye-sensitized solar cell, the film peeling between the porous semiconductor layer and the porous light-reflective insulating layer did not occur, and the adhesion was good.
The photoelectric conversion efficiency was measured in the same manner as in Example 1. As a result, it was 4.7% (short-circuit current density 15.5 (A · cm ⁻¹ ), open-circuit voltage 0.58 (V), fill factor 0.52). It was. The results are shown in Table 1.

[Comparative Example 4]
Zirconia particles having an average primary particle diameter of 50 nm between the porous light reflecting insulating layer and the catalyst conductive layer, using the porous light reflecting insulating layer paste of Comparative Example 3 as the porous light reflecting insulating layer paste. Example 1 except that the paste containing was applied with a screen printer so as to be 7 mm in length, 7 mm in width, and 7 μm in thickness centered on the center portion of the substrate, and an extra porous insulating layer was formed. Similarly, the dye-sensitized solar cell of Comparative Example 4 was produced. During the production of the dye-sensitized solar cell, the film peeling between the porous semiconductor layer and the porous light-reflective insulating layer did not occur, and the adhesion was good.
The photoelectric conversion efficiency was measured in the same manner as in Example 1. As a result, it was 5.5% (short-circuit current density 15.4 (A · cm ⁻¹ ), open-circuit voltage 0.63 (V), fill factor 0.57). It was. The results are shown in Table 1.

[Evaluation of reflectivity of porous reflective insulating layer]
Form the porous reflective insulating layer pastes of Examples 1 to 7 and Comparative Examples 2 to 4 on a transparent conductive substrate (manufactured by Nippon Sheet Glass Co., Ltd.) by a screen printing method so that the fired film thickness becomes 10 μm. And it fired at 500 degreeC for 60 minutes, and the board | substrate with a porous light reflection insulation layer was obtained.
When the reflectance of light at a wavelength of 550 nm of the obtained substrate was measured, the reflectance of light when the pastes of Examples 1 to 7 and Comparative Examples 3 and 4 were used was 80%. On the other hand, when the paste having a large content of particles (B) of Comparative Example 2 was used, the light reflectance was as low as 60%, and it was confirmed that sufficient light reflectivity could not be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the porous light reflection insulation layer which has high adhesiveness with a porous semiconductor layer and contributes to the improvement of photoelectric conversion efficiency, and the paste for porous light reflection insulation layers which can form this are obtained. It is done.

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Transparent conductive film 3 Sealing material 4 Electrolyte 5 Conductive layer (counter electrode)
6 Porous light reflection insulating layer 7 Porous semiconductor layer 10 Dye-sensitized solar cell

Claims (5)

  The surface of rutile titanium oxide particles having a volume median diameter (D50) of 100 nm or more and 1000 nm or less is coated with one or more coating materials selected from silicon compounds, magnesium compounds, aluminum compounds, zirconium compounds, and calcium compounds. Particles (A) and a metal oxide particle (B) having a volume median diameter (D50) of 1 nm or more and 30 nm or less, and a mass ratio of the particles (B) to the particles (A) [ The paste for porous light-reflective insulating layers whose particle (B) / particle (A)] is 5 / 95-40 / 60.   The paste for porous light-reflective insulating layers according to claim 1, wherein a coating amount of the coating material in the particles (A) is 1% by mass or more and 30% by mass or less.   The paste for porous light-reflective insulating layers according to claim 1 or 2, wherein the particles (B) are anatase-type titanium oxide particles.   The porous light reflection insulation layer formed using the paste for porous light reflection insulation layers in any one of Claims 1-3.   A dye-sensitized solar cell comprising the porous light-reflecting insulating layer according to claim 4.