JP2007035594A - Photoelectric cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photoelectric cell of which light utilization factor is improved in order to realize high photoelectric conversion efficiency. <P>SOLUTION: The photoelectricity cell comprises: a substrate (6) whose surface includes an electrode layer (1), on its surface, having a semiconductor film (3) formed by making the electrode layer (1) absorb photosensitive material; and a substrate (7) whose surface includes an electrode layer (2), wherein, the electrode layer (1) and the electrode layer (2) are so arranged that they face each other, electrolyte is enclosed between the semiconductor film (3) and the electrode layer (2) to form an electrolyte layer (5), a reflective layer (4) is formed between the electrolyte layer (5) and the semiconductor film (3), and at least one of the substrates and its electrode layer are transparent. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a photoelectric cell having a high photoelectric conversion efficiency in which a utilization rate of light is improved by providing a reflective layer between a semiconductor film and an electrolyte layer.

  In recent years, since titanium oxide has a high band gap, it has been suitably used as a photocatalyst, and also as a so-called photoelectric conversion material that converts light energy into electric energy. Moreover, it has come to be used also for secondary batteries such as lithium batteries, hydrogen storage materials, proton conductive materials, and the like.

The photoelectric conversion material is a material that can continuously extract light energy as electric energy, and is a material that converts light energy into electric energy using an electrochemical reaction between electrodes.
When the photoelectric conversion material is irradiated with light, electrons are generated on one electrode side, move to the counter electrode, and the electrons moved to the counter electrode move as ions in the electrolyte and return to the one electrode. Since such energy conversion is performed continuously, it is used, for example, for solar cells.

  In general solar cells, first a semiconductor film for photoelectric conversion material is formed on a support such as a glass plate coated with a transparent conductive film as an electrode, and then another transparent conductive film is used as a counter electrode. A support such as a coated glass plate is provided, and an electrolyte is sealed between these electrodes.

  When the photosensitizer adsorbed on the semiconductor for photoelectric conversion material is irradiated with sunlight, the photosensitizer absorbs light in the visible region, the electrons in the photosensitizer are excited, and the excited electrons are applied to the semiconductor. The electrons then move to the counter electrode through the transparent conductive glass electrode, and the electrons transferred to the counter electrode reduce the redox system in the electrolyte. On the other hand, the photosensitizer that has moved electrons to the semiconductor is in an oxidant state, but this oxidant is reduced by the redox system in the electrolyte and returns to its original state. Thus, since electrons flow continuously, it functions as a solar cell using a semiconductor for photoelectric conversion materials.

  As such a photoelectric conversion material, a material in which a photosensitizing dye having absorption in a visible light region is adsorbed on the surface of a semiconductor film is used. For example, Japanese Patent Laid-Open No. 1-220380 (Patent Document 1) describes a solar cell having a color former layer such as a transition metal complex on the surface of a metal oxide semiconductor. Japanese Patent Application Laid-Open No. 5-504023 (Patent Document 2) describes a solar cell having a photosensitizing dye layer such as a transition metal complex on the surface of a titanium oxide semiconductor layer doped with metal ions. .

Further, the present applicant has proposed to use a metal product semiconductor film having a pore volume in a specific range in Japanese Patent Application Laid-Open No. 11-339867 (Patent Document 3). Further, JP-A-2000-77691 (Patent Document 4) and JP-A-2001-155791 (Patent Document 5) disclose photoelectric cells using metal oxide particles having a core cell structure. Japanese Patent Laid-Open No. 2002-123065 (Patent Document 6) proposes that a metal oxide semiconductor film is used in combination with a porous metal oxide semiconductor film and a nonporous metal oxide semiconductor film.
Japanese Patent Laid-Open No. 1-220380 Japanese National Patent Publication No. 5-504023 JP 11-339867 A JP 2000-77691 A JP 2001-155791 A Japanese Patent Laid-Open No. 2002-123065

  In the solar cell as described above, it is important for improving the light conversion efficiency that the electron transfer from the photosensitizing dye layer excited by absorbing light to the titania film is important, and the electron transfer is performed quickly. Otherwise, there is a problem that the recombination of the ruthenium complex and the electrons occurs again and the light conversion efficiency is lowered. The applicant of the present application has proposed Patent Documents 3 to 5 in order to solve such problems, but the photoelectric conversion efficiency is not always sufficient, and there are restrictions on the use, and further improvements have been desired. .

  Under these circumstances, the present inventors have conducted further extensive research and found that the photoelectric conversion efficiency is improved by providing a reflective layer between the semiconductor film and the electrolyte layer, thereby completing the present invention. It came to do.

That is, the photoelectric cell according to the present invention is shown below.
[1] A substrate (6) having an electrode layer (1) on the surface and a semiconductor film (3) having a photosensitizer adsorbed on the electrode layer (1) surface, and an electrode layer on the surface A substrate (7) having (2),
The electrode layer (1) and the electrode layer (2) are arranged so as to face each other,
In a photoelectric cell comprising an electrolyte layer (5) in which an electrolyte is sealed between a semiconductor film (3) and an electrode layer (2),
A reflective layer (4) is provided between the electrolyte layer (5) and the semiconductor film (3);
A photoelectric cell in which at least one of the substrate and the electrode layer has transparency.
[2] The photoelectric cell according to [1], wherein the reflective layer includes core cell particles including a high refractive index core and a low refractive index cell.
[3] The photoelectric cell according to [1] or [2], wherein the thickness of the reflective layer is in the range of 0.4 to 10.0 μm.
[4] The photoelectric cell according to [1] to [3], wherein an average transmittance in a wavelength range of the reflective layer in a range of 400 to 1000 nm is 90% or more.
[5] The photoelectric cell according to [1] to [4], wherein the amount of adsorption of the photosensitizer in the reflective layer is 50 μg / cm ² or less. [6] The refractive index (N _C ) of the core of the core cell particles is in the range of 1.8 to 2.5, and the refractive index (N _S ) of the cell is in the range of 1.2 to 2.0. The photoelectric cell of [1] to [5], wherein the rate difference N _C −N _S is 0.2 or more.
[7] The core of the core cell particle is made of at least one selected from the group consisting of TiO ₂ , ZrO ₂ , BaTiO ₃ and Al ₂ O ₃ , and the cell is made of SiO ₂ , Al ₂ O ₃ , Si ₃ N ₄ , A photoelectric cell comprising at least one selected from the group consisting of AlN, SiO ₂ —Al ₂ O ₃ hydrophobic organic polymer, and fluorine compound.
[8] The photoelectric cell according to [1] to [7], wherein the core of the core cell particle is made of TiO ₂ and the cell is made of SiO ₂ .
[9] The photoelectric cell according to [1] to [8], wherein the average particle diameter of the core cell particles is in the range of 100 to 700 nm.

  ADVANTAGE OF THE INVENTION According to this invention, the utilization rate of light can be improved by providing a reflective layer on a semiconductor film, and the photoelectric cell which can achieve high photoelectric conversion efficiency for this reason can be provided.

The photoelectric cell according to the present invention will be specifically described below.
[Photoelectric cell]
The photovoltaic cell according to the present invention comprises:
A semiconductor film having an electrode layer (1) on the surface and adsorbing a photosensitizer on the surface of the electrode layer (1) (
3) formed substrate (6), and substrate (7) having an electrode layer (2) on the surface,
The electrode layer (1) and the electrode layer (2) are arranged so as to face each other,
In a photoelectric cell comprising an electrolyte layer (5) in which an electrolyte is sealed between a semiconductor film (3) and an electrode layer (2),
A reflective layer (4) is provided between the electrolyte layer (5) and the semiconductor film (3);
It is characterized in that at least one of the substrate and the electrode layer has transparency.

An example of such a photoelectric cell is shown in FIG.
FIG. 1 is a schematic sectional view showing an embodiment of a photoelectric cell according to the present invention, which has a transparent electrode layer 1 on the surface of a transparent substrate 6 and adsorbs a photosensitizer on the surface of the transparent electrode layer 1. The substrate on which the semiconductor film 3 is formed and the substrate having the electrode layer 2 on the surface of the substrate 7 are arranged so that the electrode layers 1 and 2 face each other, and the electrolyte is interposed between the semiconductor film 3 and the electrode layer 2. Is enclosed, and the reflective layer (4) is provided between the electrolyte layer (5) and the semiconductor film (3).

As the transparent substrate 6, a transparent and insulating substrate such as a glass substrate or an organic polymer substrate such as PET can be used.
In addition, the substrate 7 is not particularly limited as long as it has enough strength to be used, and in addition to an insulating substrate such as a glass substrate or an organic polymer substrate such as PET, metal titanium, metal aluminum, metal copper, metal nickel, etc. The conductive substrate can be used.

  The transparent electrode layer 1 formed on the surface of the transparent substrate 6 includes tin oxide, tin oxide doped with Sb, F or P, indium oxide doped with Sn and / or F, antimony oxide, zinc oxide, noble metal, etc. Conventionally known electrodes can be used.

Such a transparent electrode layer 1 can be formed by a conventionally known method such as a thermal decomposition method or a CVD method.
The electrode layer 2 formed on the surface of the substrate 7 includes electrode materials such as platinum, rhodium, ruthenium metal and ruthenium oxide, tin oxide doped with tin oxide, Sb, F or P, Sn and / or F. Conventionally known electrodes such as an electrode obtained by plating or vapor-depositing the electrode material on the surface of a conductive material such as indium oxide or antimony oxide doped with carbon, or a carbon electrode can be used.

  Such an electrode layer 2 is formed by directly coating, plating, or vapor-depositing the electrode on the substrate 7 and forming a conductive layer from a conductive material by a conventionally known method such as a thermal decomposition method or a CVD method. The electrode material can be formed on the layer by a conventionally known method such as plating or vapor deposition.

The substrate 7 may be transparent like the transparent substrate 6, and the electrode layer 2 may be a transparent electrode like the transparent electrode layer 1.
It is preferable that the visible light transmittance of the transparent substrate 6 and the transparent electrode layer 1 is high, specifically 50% or more, particularly preferably 90% or more. When the visible light transmittance is less than 50%, the photoelectric conversion efficiency may be lowered.

The resistance values of the transparent electrode layer 1 and the electrode layer 2 are each preferably 100 Ω / cm ² or less. The photoelectric conversion efficiency when the resistance value of the electrode layer is increased beyond 100 [Omega / cm ² may decrease.

The semiconductor film 3 is formed on the transparent electrode layer 1 formed on the transparent substrate 6.
The semiconductor film 3 may be formed on the electrode layer 2 formed on the substrate 7.
The thickness of the semiconductor film 3 is preferably in the range of 0.1 to 50 μm, more preferably 2 to 20 μm.

The semiconductor film 3 preferably has a pore volume of 0.05 to 0.8 ml / g and an average pore diameter of 2 to 250 nm.
When the pore volume is less than 0.05 ml / g, the spectral sensitizing dye adsorption amount is low, and when it exceeds 0.8 ml / g, the electron mobility in the film is lowered and the photoelectric conversion efficiency is lowered. is there.

As the semiconductor film 3, a conventionally known semiconductor film can be used.
For example, an inorganic semiconductor film formed from an inorganic semiconductor material, an organic semiconductor film formed from an organic semiconductor material, an organic-inorganic hybrid semiconductor film, or the like can be used.

  Examples of the organic semiconductor material include conventionally known compounds such as phthalocyanine, phthalocyanine-bisnaphthalocyanine, polyphenol, polyanthracene, polysilane, and polypyrrole.

  As the semiconductor film, an inorganic semiconductor film formed from an inorganic semiconductor material is preferably used. Among these, the use of a metal oxide as the inorganic semiconductor material is preferable because a porous metal oxide semiconductor having a high photosensitizer adsorption amount can be obtained. As such a metal oxide semiconductor film, a metal composed of at least one metal oxide selected from titanium oxide, lanthanum oxide, zirconium oxide, niobium oxide, tungsten oxide, strontium oxide, zinc oxide, tin oxide, and indium oxide. An oxide semiconductor film can be given.

  In the present invention, the semiconductor film is particularly preferably composed of titanium oxide, and further preferably composed of titanium oxide derived from peroxotitanic acid that also acts as a binder and titanium oxide particles.

Titanium oxide particles Titanium oxide particles have higher spectral sensitizing dye adsorption and higher electron mobility in the semiconductor film than other metal oxide particles, and are more stable, safer and easier to form. Etc. have excellent properties.

  As the titanium oxide particles, crystalline titanium oxides such as anatase-type titanium oxide, brookite-type titanium oxide, and rutile-type titanium oxide are preferable. Among them, anatase-type titanium oxide and brookite-type titanium oxide have a high band gap and high photoelectric conversion efficiency. A photoelectric cell can be obtained.

The crystallite diameter of such crystalline titanium oxide is preferably in the range of 5 to 50 nm, more preferably 7 to 30 nm.
For example, the crystallite size of the anatase-type titanium oxide particles can be obtained by measuring the half-value width of the peak of the (1.0. 1) plane by X-ray diffraction and calculating by the Debye-Scherrer formula. When the crystallite diameter of the titanium oxide particles is less than 5 nm, the electron mobility in the particles decreases, and when it exceeds 50 nm, the adsorption amount of the spectral sensitizing dye decreases and the photoelectric conversion efficiency decreases.

  Further, the particle diameter of the anatase-type titanium oxide particles can be measured with a laser Doppler particle size measuring instrument (manufactured by Nikkiso Co., Ltd .: Microtrac), and the average particle diameter is in the range of 5 to 600 nm, more preferably in the range of 10 to 500 nm. It is preferable that it exists in.

If the average particle diameter of the crystalline titanium oxide particles is less than 5 nm, cracks are likely to occur in the formed semiconductor film, and it is difficult to form a crack-free thick film having a film thickness described later with a small number of times. This is not preferable because the pore diameter and pore volume of the semiconductor film are decreased and the amount of adsorption of the spectral sensitizing dye is decreased.

On the other hand, if it exceeds 600 nm, the strength of the semiconductor film becomes insufficient, which is not preferable.
Moreover, when the average pore diameter is less than 2 nm, the amount of the spectral sensitizing dye adsorbed decreases, and when it exceeds 250 nm, the electron mobility may decrease and the photoelectric conversion efficiency may decrease.

  As the anatase-type titanium oxide particles, those obtained by a conventionally known method can be used, and titanium oxide particles derived from peroxotitanic acid are preferred.

Hereinafter, a method for producing titanium oxide particles derived from peroxotitanic acid will be exemplified.
First, hydrogen peroxide is added to a titanium compound aqueous solution, or a hydrated titanium oxide sol or gel, and heated to prepare peroxotitanic acid. In the present invention, peroxotitanic acid refers to titanium peroxide hydrated titanium and has absorption in the visible light region.

  The hydrated titanium oxide sol or gel is obtained by adding an acid or alkali to an aqueous solution of a titanium compound to hydrolyze it, and washing or aging by washing as necessary.

  The titanium compound is not particularly limited, and titanium salts such as titanium halide and titanyl sulfate, titanium alkoxides such as tetraalkoxy titanium, and titanium compounds such as titanium hydride can be used.

  Next, alkali, preferably ammonia and / or amine is added to peroxotitanic acid to make it alkaline, and then titanium oxide colloidal particles are obtained by heating and aging at a temperature range of 80 to 350 ° C. The titanium oxide colloidal particles obtained as necessary may be added as seed particles to peroxotitanic acid, and then the above steps may be repeated. The titanium oxide colloidal particles thus obtained are anatase-type titanium having high crystallinity by X-ray diffraction.

Next, the semiconductor film 3 contains a titanium oxide binder component together with titanium oxide particles.
Binder (Peroxotitanic acid)
As such a titanium oxide binder component, as described above, a peroxo compound obtained by dissolving hydrogenated titanic acid by adding hydrogen peroxide to an orthotitanic acid gel or sol obtained by a titanium oxide sol and / or sol-gel method or the like. Titanic acid is mentioned.

  When such a binder component is contained, the adhesion with the electrode is improved, the strength of the resulting semiconductor film is improved, and an adsorption layer of a photosensitizer can be formed on the surface of the titanium oxide particles. Furthermore, the contact area between the titanium oxide particles is increased, the electron mobility can be improved, and a photoelectric cell with high photoelectric conversion efficiency can be obtained.

  The ratio of the titanium oxide binder component to the titanium oxide particles in the semiconductor film 3 is 0.03 to 0.50, preferably 0.1 to 0.00 in terms of weight ratio in terms of oxide (titanium oxide binder component / titanium oxide particles). It is desirable to be in the range of 3.

If the weight ratio is less than 0.03, the amount of adsorption of the photosensitizer is insufficient, the adhesion to the substrate,
The strength of the semiconductor film may be insufficient.
When the weight ratio is higher than 0.50, a porous semiconductor film may not be obtained, and the photosensitizer adsorption amount may not increase.

The semiconductor film 3 preferably has a pore volume of 0.1 to 0.8 ml / g and an average pore diameter of 2 to 250 nm. When the pore volume is smaller than 0.1 ml / g, the adsorption amount of the photosensitizer is low, and when it is higher than 0.8 ml / g, the electron mobility in the film is lowered and the photoelectric conversion efficiency is reduced. May decrease. Further, when the average pore diameter is less than 2 nm, the adsorption amount of the photosensitizer decreases, and when it exceeds 250 nm, the electron mobility decreases and the photoelectric conversion efficiency may decrease.

  Such a semiconductor film can be produced using a coating liquid for forming a semiconductor film for photoelectric cells, which is composed of peroxotitanic acid as a precursor of a titanium oxide binder component, a titanium oxide particle-dispersed sol, and a dispersion medium.

The film thickness of the semiconductor film thus obtained is preferably in the range of 0.1 to 50 μm.
In the present invention, the semiconductor film 3 adsorbs the photosensitizer.
The photosensitizer is not particularly limited as long as it absorbs and excites light in the visible light region and / or infrared light region. For example, organic dyes, metal complexes, and the like can be used.

  As the organic dye, a conventionally known organic dye having a functional group such as a carboxyl group, a hydroxyalkyl group, a hydroxyl group, a sulfone group, or a carboxyalkyl group in the molecule can be used. Specifically, xanthene, coumarin, acridine, tetraphenylmethane, quinone, eosin Y, dibromofluorescein, fluorescein, fluorescein, metal-free phthalocyanine, cyanine dyes, metarocyanine dyes, triphenylmethane dyes and uranin, eosin, Examples thereof include xanthene dyes such as rose bengal, rhodamine B, and dibromofluorescein. These organic dyes have a characteristic that the adsorption rate to the semiconductor film is fast.

Examples of the metal complex include metal phthalocyanines such as copper phthalocyanine and titanyl phthalocyanine described in JP-A-1-220380 and JP-A-5-504023, chlorophyll, hemin, ruthenium-tris (2,2 ′ -Bispyridyl-4,4'-dicarboxylate), cis- (SCN-)-bis (2,2'-bipyridyl-4,4'-dicarboxylate) ruthenium, ruthenium-cis-diaqua-bis (2, Ruthenium-cis-, such as 2'-bipyridyl-4,4'-dicarboxylate)
Examples thereof include complexes of ruthenium, osmium, iron, zinc and the like, such as diaqua-bipyridyl complexes, porphyrins such as zinc-tetra (4-carboxyphenyl) porphine, and iron-hexocyanide complexes. These metal complexes are excellent in the effect of spectral sensitization and durability.

The above organic dyes and metal complexes may be used alone, or two or more kinds may be mixed and used, and an organic dye and a metal complex may be used in combination.
The adsorption method of such a photosensitizer is not particularly limited, and after forming a reflective layer described later on the semiconductor film, a solution obtained by dissolving the photosensitizer in a solvent is used as a dipping method, a spinner method, or a spray method. A general method such as absorption by a semiconductor film by a method such as drying and then drying can be employed. Furthermore, you may repeat the said absorption process as needed. Further, the photosensitizer can be adsorbed to the semiconductor film by bringing the photosensitizer solution into contact with the substrate while heating and refluxing.

  As the solvent for dissolving the photosensitizer, any solvent that dissolves the photosensitizer can be used. Specifically, water, alcohols, toluene, dimethylformamide, chloroform, ethyl cellosolve, N-methylpyrrolidone, Tetrahydrofuran or the like can be used.

The amount of the photosensitizer adsorbed on the semiconductor film is preferably 50 μg or more per 1 cm ² of the specific surface area of the semiconductor film. When the amount of the photosensitizer is less than 50 μg, the photoelectric conversion efficiency may be insufficient.

Reflective layer 4
In the photoelectric cell according to the present invention, the reflective layer 4 is provided on the semiconductor film 3.
The reflective layer 4 is composed of a binder and core cell particles composed of a high refractive index core and a low refractive index cell. The following core cell particles are difficult to absorb, so the light scattering ability is high, and the reflection layer obtained because the reflection performance is high reflects the light that was not used in the semiconductor film, and this light is irradiated to the semiconductor film, and the sensitizer As a result, the photoelectric conversion efficiency can be improved. (Core cell particles)
The core cell particles used in the present invention are composed of a high refractive index core and a low refractive index cell.

Examples of the core component include TiO ₂ , ZrO ₂ , BaTiO ₃ , Al ₂ O ₃ , Fe ₂ O ₃ , Nb ₂ O ₅ , and composites thereof. Of these, TiO ₂ , ZrO ₂ , BaTiO ₃ , and Al ₂ O ₃ are preferable because they are white and hardly absorb the wavelength of specific light. In particular, TiO ₂ has a high refractive index, and the resulting core cell particles have a high light scattering ability and a high reflection performance, so that the resulting reflective layer reflects light that was not used in the semiconductor film, and this light is irradiated onto the semiconductor film. Thus, the sensitizer can be excited and, as a result, the photoelectric conversion efficiency can be improved.

Such a core is preferably a spherical particle, and when the core particle is spherical, a spherical core cell particle is obtained, and the light scattering effect becomes higher.
The average particle size of the core particles is preferably in the range of about 100 to 700 nm.

When the average particle diameter of the core particles is less than 100 nm, the light scattering (reflecting) light is limited to a short wavelength, and the scattering effect is insufficient.
If the average particle diameter of the core particles exceeds 700 nm, long-wavelength light can be sufficiently scattered (reflected), but cracks are generated in the reflective layer, resulting in insufficient strength or adhesion to the semiconductor film. May be insufficient.

The refractive index (N _C ) of the core component is preferably in the range of 1.8 to 2.5, more preferably 1.9 to 2.3. Within this range, the core component has a refractive index (N _C ) of 1.8, which is excellent in reflection performance.
When the ratio is less than 1, it varies depending on the refractive index of the cell layer, but sufficient reflection performance cannot be obtained.

When the refractive index (N _C ) of the core component exceeds 2.5, it is difficult to obtain a material excellent in transparency, inexpensive and excellent in processability.
Then, as the cell component, the core higher refractive index than component is not particularly limited as long form cells in the core _{component, SiO 2, Al 2 O 3} , Si 3 N 4, AlN, SiO 2 -Al 2 O ₃ , hydrophobic organic polymers, fluorine compounds and the like can be mentioned. Among these, SiO ₂ can form cells uniformly on the surface of the core component, and the adsorption amount of the photosensitizer described later is low. Therefore, high light scattering (reflection) is achieved without absorbing light in the reflective layer. ) The effect is obtained.

The cell component has a refractive index (N _s ) of 1.2 to 2.0, more preferably 1.4 to 1.8. When the refractive index (N _S ) of the cell component is less than 1.2, it is difficult to densely coat the core particles, or it is difficult to obtain a material that can suppress the adsorption of the photosensitizer.
When the refractive index (N _S ) of the cell component exceeds 2.0, the difference in refractive index from the core component becomes small, and sufficient reflection performance may not be obtained.

  The thickness of the cell layer is not particularly limited as long as the average particle diameter of the core cell particles is in the range of 100 to 700 nm, and is preferably in the range of about 0.5 to 20 nm, more preferably 0.5 to 5.0 nm. .

  When the thickness of the cell layer is less than 0.5 nm, a dense cell cannot be formed, so that the dye is adsorbed to the core particles, and the light scattering (reflection) effect may not be sufficiently obtained. When the thickness of the cell layer exceeds 20 nm, the cell layer having a low refractive index is thick, so that the properties and optical characteristics of the core particles cannot be fully utilized, and the light scattering (reflection) effect may be insufficient. is there.

By using such core cell particles, incident light is scattered and can be collected on the semiconductor layer that has adsorbed the photosensitizer, so that the light utilization efficiency can be increased.
The difference between the refractive index (N _C ) of the core component of the core cell particles and the refractive index (N _S ) of the cell component is preferably 0.2 or more, more preferably 0.4 or more. Those having such a refractive index difference have high reflection performance and can effectively scatter incident light. When the difference between the refractive index (N _C ) of the core component and the refractive index (N _S ) of the cell component is less than 0.2, the light scattering (reflection) performance may be insufficient. The core cell particles used in the present invention may be particles in which one layer of the cell component is formed on the core particles or particles in which two or more layers are formed. At this time, the cell layer is preferably a particle in which components having a refractive index are sequentially formed so as to become an outer shell of the particle.

The binder component for forming the reflective layer is not particularly limited as long as the core layer particles can be combined to form the reflective layer and the adsorption of the photosensitizer can be suppressed, but SiO ₂ , TiO ₂ , Al ₂ O _3, etc. Can be mentioned. In particular, when the cell component is SiO ₂ , it is preferable to use SiO ₂ fine particles having a particle diameter of 10 nm or less because the reflection (light scattering) effect is not impaired and the film can be easily formed. it can.

  The ratio of the binder component to the core cell particles in the reflective layer 4 is in the range of 0.03 to 0.50, preferably 0.1 to 0.3, in terms of oxide-converted weight ratio (binder component / core cell particles). Is desirable. If it is this ratio, film | membrane intensity | strength can be made high and adhesiveness can be improved.

If the weight ratio is less than 0.03, the bonds between the core cell particles are weak, and the strength of the film may be insufficient, or the adhesion to the semiconductor film may be insufficient.
When the weight ratio is higher than 0.50, the ratio of the core cell particles is low, and the light scattering (reflection) effect may be insufficient.

The thickness of the reflective layer 4 is preferably in the range of 0.4 to 10.0 μm, more preferably 1.0 to 5.0 μm.
If the thickness of the reflective layer is thin, the light scattering (reflection) effect may be insufficient. Moreover, even if the thickness of the reflective layer is too thick, the moving distance of electrons becomes long, and the photoelectric conversion efficiency may be insufficient.

  The average transmittance in the range where the wavelength region of the reflective layer 4 is 400 to 1000 nm is desirably 90% or more. When the average transmittance is less than 90%, light absorption occurs, so that the light scattering (reflection) effect may be insufficient. A more preferable range of the average transmittance is 95% or more.

The reflective layer 4 may adsorb the above-described photosensitizer.
The adsorption amount of the photosensitizer of the reflective layer 4 is preferably 50 μg / cm ² or less, more preferably 20 μg / cm ² or less. If the amount of the photosensitizer adsorbed on the reflective layer 4 increases, light absorption by the photosensitizer may occur and the light scattering (reflection) effect may be insufficient. It is preferable that the photosensitizer is not substantially adsorbed on the reflective layer.

The reflective layer 4 preferably has a pore volume in the range of 0.1 to 0.8 ml / g and an average pore diameter of 2 to 250 nm. When the pore volume is small, the diffusion of the electrolyte is inhibited, and the photoelectric conversion efficiency may be lowered. In addition, when the pore volume is high, the electron mobility in the reflective layer is lowered, and the photoelectric conversion efficiency may be lowered. On the other hand, when the average pore diameter is small, the diffusion of the electrolyte is lowered, and the photoelectric conversion efficiency may be insufficient. When the average pore diameter is large, the electron mobility may be lowered and the photoelectric conversion efficiency may be lowered.

Such a reflective layer 4 can be produced using a coating solution for forming a reflective layer for an photoelectric cell, which comprises a binder component precursor, core cell particles, and a dispersion medium.
The binder component precursor used in the present invention is not particularly limited as long as it can bind the core cell particles to form a reflective layer and suppress the adsorption of the photosensitizer, and examples thereof include silica sol, titania sol, and alumina sol.

In particular, when the cell component is SiO ₂ , it is preferable to use a silica fine particle-dispersed sol having a particle diameter of 10 nm or less because the film formation is facilitated without impairing the reflection (light scattering) effect.

  As the core cell particles, the above-described core cell particles are used. The method for preparing such core cell particles is not particularly limited as long as the above-described core cell particles can be obtained, and conventionally known methods can be employed.

For example, in the case of core cell particles in which the core is made of TiO ₂ and the cell is made of SiO ₂ , a silica solution obtained by dealkalizing silica sol and sodium silicate as a silica source in a TiO ₂ colloidal particle dispersion, or an organosilicon compound / It can be obtained by adding a hydrolyzate of an organosilicon compound, depositing it on the surface of the TiO ₂ colloidal particles, aging, washing, etc. as necessary.

As the TiO ₂ colloidal particle dispersion at this time, the titanium oxide particle-dispersed sol used for the semiconductor film can be preferably used.
Alternatively, it can be obtained by spraying an organic silicon compound solution such as ethyl silicate on core particles such as TiO ₂ under vacuum or normal pressure, vapor deposition, drying and firing.

In addition, when the core is TiO ₂ and the cell is a fluorine compound, a silane coupling agent containing fluorine, a fluororesin coating agent, etc. are used as a precursor and deposited on the surface of the TiO ₂ particles, and if necessary, aged, washed and fired It can obtain by performing etc.

  The ratio of the binder component precursor and the core cell particles in the coating liquid for forming the reflective layer for photoelectric cells used in the present invention is 0.05 to 0.50 in terms of oxide weight ratio (binder component / core cell particles). Preferably it is in the range of 0.1 to 0.3.

If the weight ratio is less than 0.03, the bonds between the core cell particles are weak, and the strength of the film may be insufficient, or the adhesion to the semiconductor film may be insufficient.
When the weight ratio is higher than 0.50, the ratio of the core cell particles is low, and the light scattering (reflection) effect may be insufficient.

  Such a binder component precursor and core cell particles are contained in the coating liquid for forming a reflective layer for photoelectric cells at a concentration of 1 to 30% by weight, preferably 2 to 20% by weight in terms of oxide. Is desirable.

  The dispersion medium can be used without particular limitation as long as it can disperse the binder component precursor and the core cell particles and can be removed when dried, but alcohols are particularly preferable.

  Furthermore, the coating liquid for forming a reflective layer for photoelectric cells used in the present invention may contain a film forming aid as required. Examples of the film forming aid include polyethylene glycol, polyvinyl pyrrolidone, hydroxypropyl cellulose, polyacrylic acid, and polyvinyl alcohol. When such a film forming aid is contained in the coating solution, the viscosity of the coating solution increases, thereby obtaining a uniformly dried film, and further, the core cell particles are densely packed and the bulk density is increased. A reflective layer that is high and porous and has high adhesion to the semiconductor film can be obtained.

The method for producing a reflective layer is characterized in that such a coating liquid for forming a reflective layer for photoelectric cells is applied on a semiconductor film, dried and then cured.
The coating solution is preferably applied such that the finally formed reflective layer has a thickness in the range of 0.4 to 5.0 μm. As a coating method of the coating liquid, it can be applied by a conventionally known method such as a dipping method, a spinner method, a spray method, a roll coater method, flexographic printing, screen printing, and inkjet printing.

The drying temperature may be any temperature that can remove the dispersion medium.
As a curing method, a method such as heat curing or ultraviolet irradiation can be employed although it varies depending on the type of the binder. In addition, when the film forming aid is contained in the coating solution, the film forming aid may be decomposed by further heat treatment after the coating film is cured.

  Next, the photosensitizer is adsorbed, but the method for adsorbing the photosensitizer is not particularly limited. After the reflective layer is formed on the semiconductor film as described above, a solution obtained by dissolving the photosensitizer in a solvent is used. A general method such as dipping, spinner, spraying or the like absorbing the semiconductor film and then drying can be employed. Furthermore, you may repeat the said absorption process as needed. Further, the photosensitizer can be adsorbed to the semiconductor film by bringing the photosensitizer solution into contact with the substrate while heating and refluxing.

The adsorption amount of the photosensitizer on the reflective layer can be obtained by subtracting the adsorption amount of the photosensitizer on the semiconductor film alone from the total adsorption amount of the semiconductor film and the reflective layer.
The reflective layer may be provided between the electrodes, but is preferably provided on the surface of the transparent electrode provided on the transparent substrate surface.

In the photoelectric cell according to the present invention, the semiconductor film 3 (reflective layer 4) and the electrode layer 2 are arranged to face each other, the side surface is sealed with resin or the like, and an electrolyte is sealed between the reflective layer and the electrode. It is formed.
As the electrolyte, a conventionally known mixture of at least one compound that forms a redox system with an electrochemically active salt is used.

Examples of the electrochemically active salt include quaternary ammonium salts such as tetrapropylammonium iodide. Examples of the compound forming the redox system, quinone, hydroquinone, iodine _{^{(I - / I - 3)}} , potassium iodide, bromine _{^{(Br - / Br - 3)}} , potassium bromide, and the like.

Furthermore, in the present invention, a solid electrolyte can be used as the electrolyte.
Examples of solid electrolytes include CuI, CuBr, CuSCN, polyaniline, polypyrrole, polythiophene, arylamine-based polymers, polymers having acrylic groups and / or methacrylic groups, polyvinylcarbazole, triphenyldiamine polymers, L-valine derivative low molecular gels, poly Oligoethylene glycol methacrylate, poly (o-methoxy aniline)
, Poly (epichlorohydrin-Co-ethylene oxide),
Fluorine ions with proton conductivity such as 2,2 ', 7,7'-tetorakis (N, N-di-P-methoxyphenyl-amine) -9,9'-spirobifluorene, perfluorosulfonate In addition to exchange resins, perfluorocarbon copolymers, perfluorocarbon sulfonic acids, etc., polyethylene oxide and ion gel methods such as imidazolium cations and Br ⁻ , BF ₄ ⁻ , N— (SO ₂ CF ₃ ) ₂ form counter ions. And what added and polymerized the vinyl monomer and the PMMA monomer to this can also be used suitably. Here, the solid electrolyte includes a gel electrolyte.

  Moreover, in this invention, a solvent can also be mixed and used for the said electrolyte layer as needed. The solvent used at this time is preferably a solvent having a low solubility of the photosensitizer so that the photosensitizer adsorbed on the semiconductor film does not desorb and dissolve. Specific examples of solvents include water, alcohols, oligoethers, carbonates such as propion carbonate, phosphate esters, dimethylformamide, dimethyl sulfoxide, N-methylpyrrolidone, N-vinylpyrrolidone, sulfolane 66, sulfur compounds, and carbonic acid. Examples include ethylene and acetonitrile.

[Example]
Hereinafter, although an example explains, the present invention is not limited by these examples.
[Example 1]
Formation of semiconductor film
Preparation of titanium oxide particles (A) 5 g of titanium hydride was suspended in 1 liter of pure water, 400 g of a hydrogen peroxide solution having a concentration of 5% by weight was added over 30 minutes, and then heated to 80 ° C. to dissolve. A solution of peroxotitanic acid was prepared. 90% by volume was taken from the total amount of this solution, adjusted to pH 9 by adding concentrated aqueous ammonia, placed in an autoclave, hydrothermally treated at 220 ° C. for 5 hours under saturated vapor pressure, and titanium oxide particles (A) A dispersion was prepared. The obtained titanium oxide particles were anatase type titanium oxide having high crystallinity by X-ray diffraction. Table 1 shows the average particle diameter of the anatase-type titanium oxide particles.

Preparation of coating solution for forming semiconductor film Next, the titanium oxide particle (A) dispersion obtained above was replaced with terpineol, a high boiling point solvent, and concentrated to a concentration of 10%, and the rest of the peroxotitanic acid solution 10 was mixed with volume%, titanium in the mixed liquor TiO ₂ terms, prepare a semiconductor film-forming coating solution with the addition of hydroxypropyl cellulose as a film-forming auxiliaries such that 30 wt% of TiO ₂ by weight did.

Next, the coating solution is applied by screen printing on a transparent glass substrate on which fluorine-doped tin oxide is formed as an electrode layer, naturally dried, and subsequently irradiated with 6000 mJ / cm ² of ultraviolet rays using a low-pressure mercury lamp. The peroxo acid was decomposed to cure the coating film. The coating film was heated at 300 ° C. for 30 minutes to decompose and anneal the hydroxypropyl cellulose to form a semiconductor film.

Table 1 shows the thickness of the obtained semiconductor film and the pore volume and average pore diameter determined by the nitrogen adsorption method.
Formation of the reflective layer (1)
Preparation of Titanium Oxide Particles (B) Isopropoxide titanium and hydroxypropylcellulose were dissolved in ethanol, and water was gradually added to hydrolyze the isopropoxide titanium. 90% by volume is taken from the total amount of this solution, adjusted to pH 9 by adding concentrated aqueous ammonia, placed in an autoclave, hydrothermally treated at 250 ° C. for 5 hours under saturated vapor pressure, and titanium oxide particles (B) Was prepared. The obtained titanium oxide particles were anatase type titanium oxide having high crystallinity by X-ray diffraction. Table 1 shows the refractive index and average particle diameter of the anatase-type titanium oxide particles. The refractive index is a known refractive index of titanium oxide.

Preparation of core cell particles (1) Disperse the titanium oxide particles (B) obtained above in water and dealkalize sodium silicate so that the silicic acid solution is 1% by weight solids with respect to the titanium oxide particles. It added so that it might become a quantity, and it heated at 85 degreeC, hold | maintained for 5 hours, and repeated washing | cleaning by the decantation by centrifugation, and the core cell particle (1) was obtained. Table 1 shows the average particle diameter of the core cell particles (1) and the refractive index of the cells. In addition, the refractive index of the cell showed the known refractive index of silica.

Preparation of coating solution (1) for forming a reflective layer Next, the core cell particles (1) obtained above were replaced with terpineol and concentrated to a concentration of 10%, and silica sol having a particle size of 5 nm was mixed. A reflection layer forming coating solution (1) was prepared by adding hydroxypropylcellulose as a film forming aid so as to be 30% by weight of the solid content in the mixed solution.

  Next, the coating solution is applied onto the semiconductor film by a screen method, dried naturally, and the coating film is heated at 300 ° C. for 30 minutes to be cured, and hydroxypropylcellulose is decomposed and annealed to form the reflective layer (1). Formed.

Table 1 shows the film thickness of the obtained reflective layer (1) and the pore volume and average pore diameter determined by the nitrogen adsorption method.
Adsorption of spectral sensitizing dye Next, the concentration of ruthenium complex represented by RuL ₂ (NCS) ₂ , L = 4.4'-dicarboxy-2,2 'bipyridine as spectral sensitizing dye is 3 × 10 ⁻⁴ mol / liter. An ethanol solution was prepared. This spectral sensitizing dye solution was kept at 80 ° C., and a glass substrate on which the semiconductor film and the reflective layer (1) were formed was immersed in and adsorbed for 1 hour. Table 1 shows the amount of the spectral sensitizing dye adsorbed on the semiconductor film and the reflective layer (1).

(1) Preparation of Photoelectric Cell Mixing was performed so that the volume ratio of acetonitrile to ethylene carbonate (acetonitrile: ethylene carbonate) was 1: 4. Tetrapropylammonium iodide was 0.46 mol / liter and iodine was 0. The mixture for electrolyte layer was obtained by mixing so as to be 0.06 mol / liter.

The electrode prepared above is used as one electrode, and fluorine-doped tin oxide as the other electrode is formed as an electrode. A transparent glass substrate carrying platinum is placed on the opposite side, and the side is sealed with a resin. The above electrolyte layer mixture was sealed between the electrodes, and the electrodes were further connected with lead wires to produce a photoelectric cell (1).

The photoelectric cell (1) is a solar simulator that emits light with an intensity of 100 W / m ^{2 at} an incident angle of 9
Irradiated at 0 °, Voc (voltage in an open circuit state), Joc (density of current flowing when the circuit was short-circuited), FF (fill factor) and η (conversion efficiency) were measured. The results are shown in Table 1.

[Example 2]
Formation of Reflective Layer (2) After forming a semiconductor film in the same manner as in Example 1, the reflective layer-forming coating solution (1) prepared in the same manner as in Example 1 is finally obtained. The reflective layer (2) was formed in the same manner except that the coating was applied so as to be 1 μm.

Spectral sensitizing dye adsorption In Example 1, the spectral sensitizing dye was adsorbed in the same manner except that the glass substrate on which the semiconductor film and the reflective layer (2) were formed was immersed. Table 1 shows the amount of the spectral sensitizing dye adsorbed on the semiconductor film and the reflective layer (2).

(2) Preparation of Photoelectric Cell A photoelectric cell (2) was prepared in the same manner as in Example 1, except that the electrode on which the reflective layer (2) was formed was one electrode.

For the photoelectric cell (2), Voc, Joc, FF and η were measured. The results are shown in Table 1.
[Example 3]
Formation of Reflective Layer (3) After forming a semiconductor film in the same manner as in Example 1, the reflective layer forming coating solution (1) prepared in the same manner as in Example 1 is used to obtain the thickness of the reflective layer finally obtained. A reflective layer (3) was formed in the same manner except that the coating was applied to a thickness of 5 μm.

Spectral sensitizing dye adsorption In Example 1, the spectral sensitizing dye was adsorbed in the same manner except that the glass substrate on which the semiconductor film and the reflective layer (3) were formed was immersed. Table 1 shows the adsorption amounts of the spectral sensitizing dyes of the semiconductor film and the reflective layer (3).

(3) Preparation of Photoelectric Cell A photoelectric cell (3) was prepared in the same manner as in Example 1 except that the electrode on which the reflective layer (3) was formed was used as one electrode.

For the photoelectric cell (3), Voc, Joc, FF and η were measured. The results are shown in Table 1.
[Example 4]
Preparation of core cell particles (2) Disperse the titanium oxide particles (B) in water and add a silicic acid solution obtained by dealkalizing sodium silicate so as to have a solid content of 2% by weight with respect to the titania particles. The mixture was heated to 85 ° C. and held for 1 hour, and decantation by centrifugation was repeatedly washed to obtain core cell particles (2). Table 1 shows the average particle diameter of the core cell particles (2) and the refractive index of the cells. In addition, the refractive index of the cell showed the known refractive index of silica.
Formation of reflective layer (4)
Preparation of Reflective Layer Forming Coating Liquid (2) A reflective layer forming coating liquid (2) was prepared in the same manner as in Example 1 except that the core cell particles (2) were used.

  Next, after forming a semiconductor film in the same manner as in Example 1, the reflective layer forming coating solution (2) was similarly reflected except that the thickness of the finally obtained reflective layer was 3 μm. Layer (4) was formed.

Spectral sensitizing dye adsorption In Example 1, the spectral sensitizing dye was adsorbed in the same manner except that the glass substrate on which the semiconductor film and the reflective layer (4) were formed was immersed. Table 1 shows the adsorption amounts of the spectral sensitizing dyes of the semiconductor film and the reflective layer (4).

(4) Preparation of Photoelectric Cell A photoelectric cell (4) was prepared in the same manner as in Example 1, except that the electrode on which the reflective layer (4) was formed was one electrode.

For the photoelectric cell (4), Voc, Joc, FF and η were measured. The results are shown in Table 1.
[Example 5]
Preparation of Titanium Oxide Particles (C) Isopropoxide titanium and hydroxypropyl cellulose were dissolved in ethanol, and water was gradually added to hydrolyze the isopropoxide titanium. 90% by volume was taken from the total amount of this solution, adjusted to pH 10 by adding concentrated aqueous ammonia, placed in an autoclave, hydrothermally treated at 250 ° C. for 5 hours under saturated vapor pressure, and titanium oxide particles (C) Was prepared.
The obtained titanium oxide particles were anatase type titanium oxide having high crystallinity by X-ray diffraction. Table 1 shows the refractive index and average particle diameter of the anatase-type titanium oxide particles. The refractive index is a known refractive index of titanium oxide.

Preparation of core cell particles (3) Disperse the titanium oxide particles (C) obtained above in water and dealkalize sodium silicate so that the silicic acid solution is 1% by weight solids with respect to the titanium oxide particles. It added so that it might become a quantity, and it heated at 85 degreeC, hold | maintained for 5 hours, and repeated washing | cleaning by the decantation by centrifugation, and obtained the core cell particle (3). Table 1 shows the average particle diameter of the core cell particles (3) and the refractive index of the cells. In addition, the refractive index of the cell showed the known refractive index of silica.

Formation of the reflective layer (5)
Preparation of Reflective Layer Forming Coating Liquid (3) A reflective layer forming coating liquid (3) was prepared in the same manner as in Example 1 except that the core cell particles (3) were used.

  Next, after forming the semiconductor film in the same manner as in Example 1, the reflective layer forming coating solution (3) was similarly reflected except that the thickness of the finally obtained reflective layer was 3 μm. Layer (5) was formed.

Spectral sensitizing dye adsorption In Example 1, the spectral sensitizing dye was adsorbed in the same manner except that the glass substrate on which the semiconductor film and the reflective layer (5) were formed was immersed. Table 1 shows the amount of the spectral sensitizing dye adsorbed on the semiconductor film and the reflective layer (5).

(5) Preparation of Photoelectric Cell A photoelectric cell (5) was prepared in the same manner as in Example 1 except that the electrode on which the reflective layer (5) was formed was one electrode.

For the photoelectric cell (5), Voc, Joc, FF and η were measured. The results are shown in Table 1.
[Example 6]
Preparation of core cell particles (4) The solvent of titanium oxide particles (B) prepared in the same manner as in Example 1 was replaced with ethanol, then ethanol was replaced with hexane, and N ₂ was bubbled into an N ₂ atmosphere. Polysilazane was added as Si ₃ N ₄ to 0.8 wt% with respect to the titanium oxide particles, then heated to 65 ° C. and held for 8 hours, and decantation by centrifugation was repeatedly washed, Core cell particles (4) were obtained. Table 1 shows the average particle diameter of the core cell particles (4) and the refractive index of the cells. In addition, the refractive index of the cell showed the known refractive index of polysilazane.

Formation of reflective layer (6)
Preparation of Reflective Layer Forming Coating Liquid (4) A reflective layer forming coating liquid (4) was prepared in the same manner as in Example 1 except that the core cell particles (4) were used.

  Next, after forming a semiconductor film in the same manner as in Example 1, the reflective layer forming coating solution (4) was similarly reflected except that the thickness of the finally obtained reflective layer was 3 μm. Layer (6) was formed.

Spectral sensitizing dye adsorption In Example 1, the spectral sensitizing dye was adsorbed in the same manner except that the glass substrate on which the semiconductor film and the reflective layer (6) were formed was immersed. Table 1 shows the adsorption amounts of the spectral sensitizing dyes of the semiconductor film and the reflective layer (6).

(6) Preparation of Photoelectric Cell A photoelectric cell (6) was prepared in the same manner as in Example 1, except that the electrode on which the reflective layer (6) was formed was one electrode.

For the photoelectric cell (6), Voc, Joc, FF and η were measured. The results are shown in Table 1.
[Example 7]
Preparation of core cell particles (5) The solvent of titanium oxide particles (B) prepared in the same manner as in Example 1 was replaced with ethanol, and a solution of aluminum triisopropoxide dissolved in isopropanol and ethyl silicate were mixed with SiO 2. _The solution mixed so that ₂ / Al ₂ O ₃ = 5/1 was added at the same time with ammonia water having a concentration of 1% by weight so that the solid content was 1% by weight with respect to the titanium oxide particles. The mixture was heated to 0 ° C. and held for 1 hour, and decantation by centrifugation was repeatedly washed to obtain core cell particles (5). Table 1 shows the average particle diameter of the core cell particles (5) and the refractive index of the cells. The refractive index of the cell was a known refractive index of silica / alumina (SiO ₂ / Al ₂ O ₃ = 5/1).

Formation of reflective layer (7)
Preparation of Reflective Layer Forming Coating Solution (5) A reflective layer forming coating solution (5) was prepared in the same manner as in Example 1 except that the core cell particles (5) were used.

  Next, after forming a semiconductor film in the same manner as in Example 1, the reflective layer forming coating solution (5) was similarly reflected except that the thickness of the finally obtained reflective layer was 3 μm. Layer (7) was formed.

Spectral sensitizing dye adsorption In Example 1, the spectral sensitizing dye was adsorbed in the same manner except that the glass substrate on which the semiconductor film and the reflective layer (7) were formed was immersed. Table 1 shows the adsorption amounts of the spectral sensitizing dyes of the semiconductor film and the reflective layer (7).

(7) Preparation of Photoelectric Cell A photoelectric cell (7) was prepared in the same manner as in Example 1, except that the electrode on which the reflective layer (7) was formed was one electrode.

For the photoelectric cell (7), Voc, Joc, FF and η were measured. The results are shown in Table 1.
[Comparative Example 1]
Production of Photoelectric Cell (R1) A photoelectric cell (R1) was produced in the same manner as in Example 1 except that the reflective layer (1) was not formed.

For the photoelectric cell (R1), Voc, Joc, FF and η were measured. The results are shown in Table 1.
[Comparative Example 2]
Preparation of Reflective Layer Film Forming Coating Solution (R1) Titanium oxide particles (B) obtained in the same manner as in Example 1 were replaced with terpineol, concentrated and concentrated to a concentration of 10%, and oxidized with a particle size of 10 nm. A titanium sol was mixed, and hydroxypropylcellulose was added as a film forming aid so as to have a solid content of 30% by weight in the mixed liquid to prepare a reflection layer film forming coating liquid (R1).

Formation of Reflective Layer (R1) After forming a semiconductor film in the same manner as in Example 1, the reflective layer forming coating solution (R1) was applied so that the thickness of the finally obtained reflective layer was 3 μm. In the same manner, a reflective layer (R1) was formed.

Spectral sensitizing dye adsorption In Example 1, the spectral sensitizing dye was adsorbed in the same manner except that the glass substrate on which the semiconductor film and the reflective layer (R1) were formed was immersed. Table 1 shows the amount of the spectral sensitizing dye adsorbed on the semiconductor film and the reflective layer (R1).

(R2) Preparation of Photoelectric Cell A photoelectric cell (R2) was prepared in the same manner as in Example 1 except that the electrode on which the reflective layer (R1) was formed was one electrode.

Voc, Joc, FF and η were measured for the photoelectric cell (R2). The results are shown in Table 1.
[Comparative Example 3]
Preparation of Core Cell Particles (R1) After replacing the solvent of silica sol (manufactured by Catalytic Chemical Industry Co., Ltd .: SS-550, average particle size 550 nm, SiO ₂ concentration 20% by weight) with methanol, and further substituting with hexane, N ₂
Is bubbled into an N ₂ atmosphere, and polysilazane is made Si ₃ N _{4 with} respect to silica particles.
It added so that it might become 8 weight%, and it heated at 65 degreeC and hold | maintained for 8 hours, and repeated decantation by centrifugation and wash | cleaned and obtained the core cell particle (R1). Table 1 shows the average particle diameter of the core cell particles (R1) and the refractive index of the cells. In addition, the refractive index of the cell showed the known refractive index of polysilazane.

Formation of reflective layer (R2)
Preparation of Reflective Layer Forming Coating Liquid (R2) A reflective layer forming coating liquid (R2) was prepared in the same manner as in Example 1 except that the core cell particles (R1) were used.

  Next, after forming a semiconductor film in the same manner as in Example 1, the reflective layer forming coating solution (R2) was similarly reflected except that the thickness of the finally obtained reflective layer was 3 μm. Layer (R2) was formed.

Spectral sensitizing dye adsorption In Example 1, the spectral sensitizing dye was adsorbed in the same manner except that the glass substrate on which the semiconductor film and the reflective layer (R2) were formed was immersed. Table 1 shows the adsorption amounts of the spectral sensitizing dyes of the semiconductor film and the reflective layer (R2).

(R3) Preparation of Photoelectric Cell A photoelectric cell (R3) was prepared in the same manner as in Example 1, except that the electrode on which the reflective layer (R2) was formed was one electrode.

  Voc, Joc, FF and η were measured for the photoelectric cell (R3). The results are shown in Table 1.

FIG. 1 shows a schematic diagram of the photovoltaic cell of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Transparent electrode layer 2 ... Electrode layer 3 ... Semiconductor film 4 ... Reflective layer 5 ... Electrolyte layer 6 ... Transparent substrate 7 ... Substrate

Claims (9)

A substrate (6) comprising a semiconductor film (3) having an electrode layer (1) on the surface and adsorbing a photosensitizer on the surface of the electrode layer (1);
The substrate (7) having the electrode layer (2) on the surface is arranged so that the electrode layer (1) and the electrode layer (2) face each other,
In a photoelectric cell comprising an electrolyte layer (5) in which an electrolyte is sealed between a semiconductor film (3) and an electrode layer (2),
A reflective layer (4) is provided between the electrolyte layer (5) and the semiconductor film (3);
At least one substrate and an electrode layer have transparency, The photoelectric cell characterized by the above-mentioned.   The photoelectric cell according to claim 1, wherein the reflective layer includes core cell particles including a high refractive index core and a low refractive index cell.   The photoelectric cell according to claim 1 or 2, wherein the thickness of the reflective layer is in the range of 0.4 to 10.0 µm.   The photoelectric cell according to any one of claims 1 to 3, wherein an average transmittance in a wavelength range of 400 to 1000 nm of the reflective layer is 90% or more. The photoelectric cell according to claim 1, wherein the adsorption amount of the photosensitizer in the reflective layer is 50 μg / cm ² or less. The core cell particles have a core refractive index (N _C ) in the range of 1.8 to 2.5, a cell refractive index (N _S ) in the range of 1.2 to 2.0, and a refractive index difference N The photoelectric cell according to claim 1, wherein _C— N _S is 0.2 or more. The core of the core cell particle is made of at least one selected from the group consisting of TiO ₂ , ZrO ₂ , BaTiO ₃ and Al ₂ O ₃ , and the cell is made of SiO ₂ , Al ₂ O ₃ , Si ₃ N ₄ , AlN, and SiO. ₂ -Al ₂ O ₃ hydrophobic organic polymers, photovoltaic cell according to claim 1, characterized in that it consists of at least one selected from the group consisting of fluorine compounds. The photoelectric cell according to claim 1, wherein the core of the core cell particle is made of TiO ₂ , and the cell is made of SiO ₂ . The photoelectric cell according to any one of claims 1 to 8, wherein an average particle diameter of the core cell particles is in a range of 100 to 700 nm.

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