JP2001320068A - Transparent photoelectric converting element, photo cell using the same, optical sensor and window glass - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a see-through type photoelectric converting element and a photo cell in which a high beam transmissivity is compatible with a superior photoelectric converting function, and to provide an optical sensor using the element and interior goods which have an optical poser generating function especially a window glass. SOLUTION: This photoelectric converting element is constituted by at least a transparent conductive layer, a semiconductor layer, a charge transfer layer and a transparent counter electrode. The transparent photoelectric converting element has features having more than 80% that the beam transparent part area has a ratio of more than 80% of the whole photo sensitive part relating to photoelectric conversion, and has a wavelength region which indicates a beam transmissivity of over 10% between 400 to 700 nm wavelength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to photoelectric conversion (photoelectric power generation).
The present invention relates to an optically transparent thin-layer photoelectric conversion element having excellent energy conversion efficiency.

[0002]

2. Description of the Related Art Photoelectric conversion devices are widely used in the industrial fields of energy conversion and light sensing, and are represented by high-sensitivity solid-state junction devices using Si pn junctions or compound semiconductor heterojunctions. And widespread. Currently, photovoltaic (PV) cells for photovoltaic power generation use solar cells using solid junctions of single crystal silicon, polycrystalline silicon, amorphous silicon, and compound semiconductors such as cadmium telluride and indium copper selenide. It has become. Among these existing technologies, amorphous silicon solar cells, which are the most powerful in terms of performance and cost ratio, can use visible light up to 800 nm, open circuit voltage of 0.7 V or more and energy conversion efficiency close to 10%. give. At the same time, these solid-junction batteries are also used for light sensing, image input and digital imaging.

[0003] However, as the needs of society diversify, an element which has a photoelectric conversion function and can simultaneously use a part of optical information (image) and light energy inputted to the element for a second purpose. And systems are required. For example, in the use of solar energy, a solar system that can simultaneously perform photoelectric conversion and heat storage is important as one means of cogeneration. For this purpose, there is a need for a technology for efficiently transmitting light in a wavelength region that has not been used for photoelectric conversion to a portion that performs photoelectric conversion, transmitting the light efficiently, converting the heat into heat in a lower-layer device, and storing the heat. Light transmissivity is required for the part to be performed. In addition, when a material with a photoelectric conversion function is used for window glass or interiors, the material must be supplied as a highly transparent sheet, and the visible scenery and images must be (visually) uniform and of high quality. Become.

However, solid-junction solar cells using silicon or a compound semiconductor as a photoelectric conversion material are basically opaque, and are difficult to apply in this respect. Therefore, in order to make the solid junction photovoltaic cell light-transmitting, a mesh-type photovoltaic cell has been proposed in which small holes or slits are provided at regular intervals in opaque portions of the photovoltaic cell and a part of incident light is transmitted.
In this method, since a part of the light receiving area is replaced with a light transmitting port (a hole having no photoelectric conversion ability), the light transmitting amount is increased, while the light receiving amount, that is, the photoelectric conversion efficiency is reduced monotonously. Therefore, it is difficult to increase light transmittance while maintaining sufficient photoelectric conversion efficiency.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a novel photoelectric conversion element and a photovoltaic cell (for example, a solar cell) having an optically transparent property while maintaining a relatively high energy conversion efficiency. In particular, it is an object of the present invention to provide a see-through type photoelectric conversion element and a photovoltaic cell having both high light transmittance and excellent photoelectric conversion function. It is still another object of the present invention to provide an optical sensor using the same and an interior article having a photovoltaic function, particularly a window glass.

[0006]

As a result of intensive studies in view of the above-mentioned objects, the present inventors have developed a photoelectric conversion element comprising at least a transparent conductive layer, a semiconductor layer, a charge transfer layer, and a transparent counter electrode. The light-transmitting portion has an area ratio of 80% or more among all the light-receiving portions involved, and the light-transmitting portion is designed to have a wavelength region showing a light transmittance of 10% or more between wavelengths of 400 to 700 nm. As a result, they have found that a see-through type photoelectric conversion element having both high light transmittance and excellent photoelectric conversion function can be obtained, and arrived at the present invention.

That is, the photoelectric conversion element of the present invention is characterized in that the transparent semiconductor electrode is used so that the area ratio of the portion exhibiting light transmittance in the visible light region is 80% or more. In the conventional method of providing a mesh structure by providing small holes or slits in an opaque portion, the upper limit of the ratio of the light transmitting portion is practically 50% due to the problem of lowering the photoelectric conversion efficiency. By using a transparent semiconductor electrode, it is possible to increase the ratio of the light transmitting portion.

The photovoltaic cell (solar cell), photosensor and window glass of the present invention use the photoelectric conversion element of the present invention.

According to the present invention, when the following conditions are satisfied, a photoelectric conversion element having more excellent photoelectric conversion efficiency can be obtained.

(1) It is preferable that an area ratio occupied by a light-transmitting portion of all the light receiving portions involved in photoelectric conversion is 90% or more and 99% or less.

(2) It is preferable that a metal lead for improving the conductivity of the electrode is provided in a non-light-transmitting portion of all light-receiving portions involved in photoelectric conversion.

(3) The wavelength range in which the light transmittance shows 10% or more is preferably 500 to 700 nm, more preferably 600 to 7 nm.
It is preferably between 00 nm.

(4) It is preferable that the wavelength region having a light transmittance of 20% or more is between 400 and 700 nm, preferably between 500 and 700 nm, more preferably between 600 and 700 nm.

(5) The thickness of the transparent conductive layer is 0.02 to 10 μm
The thickness of the semiconductor layer is 0.1 to 25 μm, the thickness of the charge transfer layer is 0.001 to 50 μm, and the thickness of the transparent counter electrode is
It is preferably from 0.02 to 10 μm.

(6) The transparent conductive layer and the transparent counter electrode are preferably made of a compound obtained by doping fluorine into indium-tin composite oxide or tin oxide.

(7) The semiconductor layer is preferably made of semiconductor fine particles.

(8) The semiconductor layer is preferably dye-sensitized.

(9) The semiconductor layer is preferably made of an n-type semiconductor, and in particular, at least one or more n-type semiconductors selected from titanium oxide, zinc oxide, tin oxide, tungsten oxide and niobium oxide It is preferred that

(10) The charge transfer layer is preferably an ion conductive electrolyte or a room temperature molten salt electrolyte.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The photoelectric conversion device of the present invention comprises at least a transparent conductive layer, a semiconductor layer, a charge transfer layer, and a transparent counter electrode, and has a light transmittance of 80% or more with respect to all light-receiving portions involved in photoelectric conversion. It has a portion.

In the present invention, the term “light transmittance” refers to a property by which the light transmittance can be sufficiently confirmed by visual observation. Specifically, the light transmittance is within a visible wavelength range of 400 nm to 700 nm. This means that at least one region of a wavelength indicating 10% or more is included. Here, the light transmittance is measured by collecting the transmitted light with an integrating sphere, placing the light-receiving surface of the portion of the element related to photoelectric conversion perpendicular to the monochromatic light for analysis, and measuring the light transmission. Expressed as a ratio (percentage) of light intensity / incident light intensity.

In the present invention, the region of 500 to 700 nm, especially
It is preferable that the film is light-transmissive in the region of 600 to 700 nm. In the visible wavelength region (400 to 700 nm), it is preferable that the total of the light transmitting wavelength regions accounts for 30% or more, particularly 50% or more. Further, the light transmittance is preferably
It is at least 20%, more preferably at least 30%. The integrated transmittance of light in the visible wavelength region (ie, 400
The ratio of the sum of the transmission intensities to the sum of the incident intensities of up to 700 nm) is preferably 30% to 70%, and more preferably 40% to 60%, although it depends on the application. Also, 400nm
Light having a wavelength of less than 700 nm or more than 700 nm may or may not be transmitted depending on the use of the transparent photoelectric conversion element of the present invention.
For example, when the transmitted infrared rays are actively used, the transmitted light may have an element configuration, and when the infrared rays should be shielded, the absorbed element configuration may be used.

[1] Transparent photoelectric conversion element The transparent photoelectric conversion element of the present invention has at least one semiconductor layer as a photosensitive layer. The configuration of the transparent photoelectric conversion element of the present invention, as long as it satisfies the condition of light transmittance that specifies the present invention,
Solid-junction type (single crystal, amorphous, etc.) may be used, and the semiconductor may itself have photosensitivity or may be sensitized by a dye, but preferably, as shown in FIG.
Transparent conductive layer 10, undercoat layer 60, photosensitive layer 20, charge transfer layer 30,
The counter electrode transparent conductive layer 40 is laminated in this order, and the photosensitive layer 20 is dye 22
Semiconductor particles 21 sensitized by
And a charge transporting material 23 that has penetrated into the gap between the two. The photosensitive layer may have a single-layer structure or a multilayer structure. The charge transport material 23 is composed of the same components as the materials used for the charge transfer layer 30. Further, in order to impart strength to the transparent photoelectric conversion element, a transparent substrate 50 may be provided on the transparent conductive layer 10 side and / or the counter electrode transparent conductive layer 40 side. Hereinafter, in the present invention, the transparent conductive layer 10
The layer composed of the optional transparent substrate 50 is referred to as a “transparent conductive support”, and the layer composed of the counter electrode transparent conductive layer 40 and the optional transparent substrate 50 is referred to as a “transparent counter electrode”. A photovoltaic cell connects the transparent photoelectric conversion element to an external circuit to perform work. In the transparent photoelectric conversion element of the present invention, light enters from one side or both sides, a part of the light is absorbed by the photosensitive layer, photoelectric conversion is performed, and the light is transmitted to the other side.

In the transparent photoelectric conversion device of the present invention shown in FIG. 1, when the semiconductor fine particles are an n-type semiconductor, the light incident on the photosensitive layer 20 containing the semiconductor fine particles 21 sensitized by the dye 22 The excited, high-energy electrons in the excited dye 22 and the like are transferred to the conduction band of the semiconductor fine particles 21 and further reach the transparent conductive layer 10 by diffusion. Then the dye
Molecules such as 22 are oxidized. In photovoltaic cells,
The electrons in the transparent conductive layer 10 return to an oxidized substance such as the dye 22 through the counter-electrode transparent conductive layer 40 and the charge transfer layer 30 while working in an external circuit, and the dye 22 is regenerated. The photosensitive layer 20 functions as a negative electrode (photo anode). When the semiconductor particles are p-type, the excited dye injects holes into the valence body of the semiconductor particles,
The photosensitive layer acts as a positive electrode (photocathode). In addition, at the boundaries of the respective layers (for example, the boundary between the transparent conductive layer 10 and the photosensitive layer 20, the boundary between the photosensitive layer 20 and the charge transfer layer 30, the boundary between the charge transfer layer 30 and the counter electrode transparent conductive layer 40, etc.) The constituent components of each layer may be mutually diffused and mixed. Hereinafter, each layer will be described in detail.

(A) Transparent conductive support The transparent conductive support is composed of two layers, a transparent conductive layer and a transparent substrate supporting the transparent conductive layer. As the conductive agent used for the transparent conductive layer, metal (for example, platinum, gold, silver, copper, aluminum, rhodium, indium, etc.), carbon, or conductive metal oxide (indium-tin composite oxide, tin oxide doped with fluorine) Etc.). Among these, a conductive metal oxide (particularly tin dioxide doped with fluorine) is preferable from the viewpoint of optical transparency.

The lower the surface resistance of the conductive support, the better. The preferred range of the surface resistance is 100 Ω / □ or less, more preferably 40 Ω / □ or less. The lower limit of the surface resistance is not particularly limited, but is usually about 0.1Ω / □.

The transparent conductive support is required to be substantially transparent, and has a region having a light transmittance of 10% or more in a wavelength range of 400 to 700 nm. Preferably,
The light transmittance in the wavelength range of 400 to 800 nm is preferably at least 50%, particularly preferably at least 70%.

In order to ensure sufficient transparency and to provide high conductivity, the amount of the conductive metal oxide applied is preferably 0.01 to 100 g per 1 m ² of the support. The thickness of the conductive layer is preferably about 0.02 to 10 μm.

The transparent conductive support is preferably formed by applying a transparent conductive layer made of a conductive metal oxide on the surface of a transparent substrate such as glass or plastic, by sputtering, vapor deposition or the like. Various glasses can be selected according to the use of the photoelectric conversion element or the photovoltaic cell. Soda lime float glass is preferred in terms of cost. For a low-cost and flexible photoelectric conversion element or solar cell, a transparent polymer film provided with a conductive layer is preferably used. Transparent polymer film materials include tetraacetyl cellulose (TAC),
Polyethylene terephthalate (PET), polyethylene naphthalate (PEN), syndiotactic polysterene (SPS), polyphenylene sulfide (PPS), polycarbonate (PC), polyarylate (PAr), polysulfone (PSF), polyester sulfone (PES) , Polyetherimide (PEI), cyclic polyolefin, brominated phenoxy and the like.

For the purpose of lowering the resistance of the transparent conductive support,
It is preferable that the metal leads be provided in a pattern such as a lattice shape or a parallel line shape. The material of the metal lead is aluminum, copper,
Metals such as silver, gold, platinum and nickel are preferred. The metal lead is preferably provided on a transparent substrate by vapor deposition, sputtering, or the like, and a transparent conductive layer such as fluorine-doped tin oxide or an ITO film is preferably provided thereon. After the transparent conductive layer is provided on the transparent substrate, a metal lead may be provided on the transparent conductive layer. In any case, the structure is such that it is electrically connected to the transparent conductive layer.

Since the portion where the metal lead is provided is usually opaque, the transparent aperture ratio of the device of the present invention (refers to the ratio of the area occupied by the light transmissive portion of all the light receiving portions involved in photoelectric conversion). Here, the total light receiving portion related to the photoelectric conversion is a region having the above-described stacked structure capable of performing the photoelectric conversion.) Therefore, the ratio of the metal lead to the light receiving area needs to be within 20%. It is preferably 1% or more and 10% or less in view of the effect of reducing the resistance and improving the photoelectric conversion efficiency. Specifically, the line width is 10 μm to 1 mm, and the thickness is 0.1 μm.
The wiring is provided at a suitable interval as a wiring of m to 5 μm.

(B) Photosensitive Layer In the photosensitive layer, the semiconductor acts as a photoreceptor, absorbs light to separate charges, and generates electrons and holes. In a dye-sensitized semiconductor, light absorption and thus generation of electrons and holes mainly occur in the dye, and the semiconductor is responsible for receiving and transmitting the electrons or holes. The semiconductor used in the present invention is preferably an n-type semiconductor which gives an anode current by conducting electrons as carriers under photoexcitation.

(1) Semiconductors Semiconductors include simple semiconductors, III-V based compound semiconductors,
Metal chalcogenides (oxides, sulfides, selenides, etc.) or compounds having a perovskite structure (eg, strontium titanate, calcium titanate, sodium titanate, barium titanate, potassium niobate, etc.) can be used. it can.

Preferred metal chalcogenides include titanium, tin, zinc, iron, tungsten, zirconium, hafnium, strontium, indium, cerium, yttrium, lanthanum, vanadium, niobium or tantalum oxide, cadmium, zinc, lead and silver. , Antimony or bismuth sulfide, cadmium or lead selenide, cadmium telluride and the like. Other compound semiconductors include phosphides such as zinc, gallium, indium and cadmium, selenides of gallium-arsenic or copper-indium, and sulfides of copper-indium.

Preferred specific examples of the semiconductor used in the present invention
Is TiO_Two, SnO_Two, Fe_TwoO_Three, WO_Three, ZnO, Nb_TwoO_Five, V_TwoO_Five, Cd
S, ZnS, PbS, Bi_TwoS_Three, FeS_Two, CdSe, ZnSe, SnSe, CdT
e, GaP, InP, GaAs, TiSrO_Three, KTiO_Three, CuInS_Two, CuInSe_Two
Etc., more preferably TiO_Two, SnO _Two, WO_Three, ZnO or
Nb_TwoO_FiveAnd most preferably TiO_TwoIt is. These materials
料 ２ 以上 ２ ２ ２ ２ ２ ２
It may be used as a complex such as a body.

The semiconductor used in the present invention may be single crystal, polycrystal, or amorphous. A single crystal is preferable from the viewpoint of conversion efficiency, but a polycrystal is preferable from the viewpoint of manufacturing cost, securing of raw materials, energy payback time, and the like, and a porous film using semiconductor fine particles is particularly preferable.

The particle size of the semiconductor fine particles is generally on the order of nm to μm, but the average particle size of the primary particles determined from the diameter when the projected area is converted into a circle is preferably from 5 to 200 nm, and from 8 to 200 nm. 100 nm is more preferred. The average particle size of the semiconductor fine particles (secondary particles) in the dispersion is preferably 0.01 to 20 μm.

Two or more types of fine particles having different particle size distributions may be mixed, in which case the average size of the small particles is 5 nm.
It is preferred that: For the purpose of improving the light capture rate by scattering incident light, semiconductor particles having a large particle size, for example, about 300 nm may be mixed.

As a method for producing semiconductor fine particles, Sakuhana Shizuo's "Sol-Gel Method Science" Agne Shofusha (1998), Technical Information Association "Sol-Gel Method for Thin Film Coating" (1995 ), Tadao Sugimoto, "Synthesis of Monodisperse Particles and Size Morphology Control by New Synthetic Gel-Sol Method", Materia, Vol. 35, No. 9, 1012-1018.
The gel-sol method described on page (1996) is preferred. Also De
Also preferred is a method developed by Gussa to produce oxides by high temperature hydrolysis of chlorides in oxyhydrogen salts.

When the semiconductor fine particles are titanium oxide, any of the above-mentioned sol-gel method, gel-sol method, and high-temperature hydrolysis method in a chloride oxyhydrogen salt are preferable, but furthermore, Manabu Kiyono's “Titanium oxide physical properties and Applied Technology "Gihodo Publishing (1997)
The sulfuric acid method and the chlorine method described in (1) can also be used. Further, the sol-gel method is described in Barb et al., Journal of American Ceramic Society, Vol.
12, No. 3, pp. 3157-3171 (1997), and Burnside et al., Chemistry of Materials, No. 10
Vol. 9, No. 9, pages 2419 to 2425 are also preferable.

(2) Formation of Semiconductor Fine Particle Layer In order to coat semiconductor fine particles on a conductive support, usually,
In addition to the method of applying a dispersion or colloid solution of semiconductor fine particles on a conductive support, the aforementioned sol-gel method or the like is used. In consideration of mass production of photoelectric conversion elements, physical properties of semiconductor fine particle liquid, flexibility of a conductive support, and the like, a wet film forming method is relatively advantageous. As a wet film forming method,
The coating method and the printing method are typical.

As the dispersion medium, water or various organic solvents (eg, methanol, ethanol, isopropyl alcohol, dichloromethane, acetone, acetonitrile, ethyl acetate, etc.) can be used. At the time of dispersion, a polymer, a surfactant, an acid, a chelating agent and the like may be used as necessary for the purpose of a dispersing aid, a void controlling agent and the like.

The application method includes a roller method and a dip method as an application system, an air knife method and a blade method as a metering system.
-4589, the wire bar method, US Patent 268
The slide hopper method, extrusion method, curtain method, and the like described in Nos. 1294, 2761419, and 2761791 are preferable. As a general-purpose machine, a spin method or a spray method is also preferable.

The layer of semiconductor fine particles is not limited to a single layer, but a multi-layer coating of a dispersion of semiconductor fine particles having different particle diameters, or a coating layer containing semiconductor fine particles of different types (or different binders and additives) may be formed in multiple layers. It can also be applied. Multilayer coating is effective even when the film thickness is insufficient by one coating. The extrusion method or the slide hopper method is suitable for multilayer coating. In the case of multi-layer coating, multi-layer coating may be performed at the same time, or several to dozens of times may be sequentially applied. Furthermore, a screen printing method can also be preferably used in the case of successive coating.

In general, as the thickness of the semiconductor fine particle layer (same as the thickness of the photosensitive layer) becomes larger, the amount of dye carried per unit projected area increases, so that the light capture rate increases, but the diffusion distance of generated electrons increases. Therefore, the loss due to charge recombination also increases. In the present invention, it is necessary to ensure light transmittance,
From this viewpoint, the semiconductor fine particle layer is preferably thin. Therefore, the preferred thickness of the semiconductor fine particle layer is 0.1 to 25 μm
, More preferably 0.3 to 20 μm, still more preferably 0.5 to 15 μm, and particularly preferably 1 to 10 μm. Support 1 m ² per coating amount of the semiconductor fine particles 0.1 to 3
0 g is preferable, and 1 to 12 g is more preferable.

After the above-mentioned semiconductor fine particles are coated on the conductive support, the semiconductor fine particles are brought into electronic contact with each other, and a heat treatment is performed to improve the strength of the coating film and the adhesion to the support. Apply. Preferred heating temperature range is 40
℃ 700 or less, more preferably 100 ℃ 600
It is below ° C. When a support having a low melting point or softening point, such as a polymer film, is used for the transparent support, the heat treatment temperature is preferably as low as possible. The lowering of the temperature can be achieved by the above-described combined use of semiconductor fine particles having a size of 5 nm or less, heat treatment in the presence of a mineral acid, or irradiation with ultraviolet rays.

The semiconductor fine particle layer preferably has a large surface area for the purpose of increasing the amount of dye adsorbed, and the ratio (roughness factor) given by the surface area to the projected area of the layer is preferably 10 times or more. It is preferably at least two times. The upper limit is not particularly limited, but is usually about 1000 times.

(3) Dyes Sensitizing dyes used in the photosensitive layer include organometallic complex dyes,
Porphyrin dyes, phthalocyanine dyes or methine dyes are preferred. Specifically, it is the visible wavelength range of 40
The sensitizing dye is selected so as to have a wavelength range showing a light transmittance of 10% or more between 0 nm and 700 nm. To maintain the transparency in the visible region of the photoelectric conversion element, and to increase the conversion efficiency by widening the wavelength region capable of photoelectric conversion as much as possible, even if two or more dyes having a peak outside the visible wavelength region are mixed. Good. The dyes to be mixed and the ratio thereof may be selected so as to match the wavelength range and the intensity distribution of the target light source.

Such a dye is a suitable interlocking group capable of adsorbing to the surface of the semiconductor fine particles.
It is preferable to have Preferred linking groups include
COOH group, OH group, SO ₃ H group, a cyano group, -P (O) (OH) 2 group, -OP
(O) (OH) ₂ groups or chelating groups having π conductivity such as oximes, dioximes, hydroxyquinolines, salicylates and α-ketoenolates. Among them, a COOH group, a -P (O) (OH) ₂ group and a -OP (O) (OH) ₂ group are particularly preferable. These groups may form a salt with an alkali metal or the like, or may form an intramolecular salt. In the case of a polymethine dye, if the methine chain contains an acidic group as in the case of forming a squarylium ring or a croconium ring, this portion may be used as a bonding group.

Hereinafter, preferred sensitizing dyes for use in the photosensitive layer will be specifically described. (A) Organic metal complex dye When the dye is a metal complex dye, the metal atom is ruthenium
Ru is preferred. Ruthenium complex dyes include:
For example, U.S. Pat.Nos. 4,492,721, 4,684,537, 5,084,365
No. 5,350,644, No. 5463057, No. 5,525,440, JP-A-7
-249790, Japanese Translation of PCT International Publication No. 10-504512, and the complex dyes described in World Patent No. 98/50393.

Further, the ruthenium complex dye used in the present invention is preferably represented by the following general formula (I): (A ₁ ) _p Ru (Ba) (Bb) (Bc) (I) In the general formula (I), A ¹ is C
1, represents a ligand selected from the group consisting of SCN, H ₂ O, Br, I, CN, NCO and SeCN, and p is an integer of 0 to 3. B-
a, Bb and Bc are each independently the following formulas B-1 to B-10:

[0052]

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(Provided that R ₁₁ represents a hydrogen atom or a substituent; examples of the substituent include a halogen atom, a substituted or unsubstituted alkyl group having 1 to 12 carbon atoms, a substituted or unsubstituted alkyl group having 7 to 12 carbon atoms, An unsubstituted aralkyl group, or a substituted or unsubstituted aryl group having 6 to 12 carbon atoms, a carboxylic acid group, a phosphate group (these acid groups may form a salt), and an alkyl group And the alkyl part of the aralkyl group may be linear or branched, and the aryl part of the aryl group and the aralkyl group may be monocyclic or polycyclic (condensed ring, ring assembly). Represents an organic ligand. Ba, Bb and Bc
May be the same or different.

Preferred specific examples of the organometallic complex dye are shown below, but the present invention is not limited thereto.

[0055]

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[0056]

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[0057]

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(B) Methine Dye Preferred methine dyes for use in the present invention are polymethine dyes such as cyanine dyes, merocyanine dyes, and squarylium dyes. Examples of the polymethine dye preferably used in the present invention, JP-A-11-35836, JP-A-11-158
No. 395, JP-A-11-163378, JP-A-11-214730, JP-A-11-214731, European Patents 892411 and 911841. The synthesis of these dyes is described in FM Hamer, Heterocyclic Compounds-Cyanine Soybeans and Related Compounds (Heterocyclic Compounds).
nds-Cyanine Dyes and Related Compounds), John Wiley & Sons
New York, London, 1964, DM
DMSturmer, Heterocyclic Compounds-Special Topics in Heterocyclic Compounds-Sp
ecial topics in heterocyclic chemistry), Chapter 18
Chapter 14, Sections 482-515, John Wiley & Sons, Inc.- New York,
London, 1977, "Rod's Chemistry of
Carbon Compounds (Rodd's Chemistry of Carbon)
Vol.IV, part B, 1977, Chapter 15,
369-422, Elsevier Science Public Company, Inc.
ompany Inc.), New York, UK Patent 1,077,61
No. 1, Ukrainskii Khimicheskii Zhurnal, Volume 40, Volume 3
Issue, pp. 253-258, Dyes and Pigments, Vol. 21, 227-
It is described on page 234 and the references cited in these references.

In addition, phthalocyanine and naphthalocyanine and derivatives thereof, metal phthalocyanine, metal naphthalocyanine and derivatives thereof, porphyrins including tetraphenylporphyrin and tetraazaporphyrin and derivatives thereof, and metal porphyrin and derivatives thereof are also preferably used. Can be. Further, dyes used for dye lasers can also be used in the present invention.

(4) Adsorption of Dye on Semiconductor Fine Particles The dye is adsorbed on the semiconductor fine particles by immersing a conductive support having a well-dried semiconductor fine particle layer in a dye solution or by dissolving the dye solution in a semiconductor solution. A method of applying to the fine particle layer can be used. In the former case, a dipping method, a dipping method, a roller method, an air knife method, or the like can be used. In the case of the immersion method, the dye may be adsorbed at room temperature or may be heated and refluxed as described in JP-A-7-249790. Examples of the latter coating method include a wire bar method, a slide hopper method, an extrusion method, a curtain method, a spin method, and a spray method. Preferred solvents for dissolving the dye include, for example, alcohols (methanol, ethanol, t-butanol, benzyl alcohol, etc.), nitriles (acetonitrile, propionitrile, 3-methoxypropionitrile, etc.), nitromethane, halogenated Hydrocarbons (dichloromethane, dichloroethane, chloroform, chlorobenzene, etc.), ethers (diethyl ether, tetrahydrofuran, etc.), dimethyl sulfoxide, amides (N, N-dimethylformamide, N, N-dimethylacetamide, etc.), N-methyl Pyrrolidone, 1,3-dimethylimidazolidinone, 3-methyloxazolidinone, esters (ethyl acetate, butyl acetate, etc.),
Examples include carbonates (diethyl carbonate, ethylene carbonate, propylene carbonate, etc.), ketones (acetone, 2-butanone, cyclohexanone, etc.), hydrocarbons (hexane, petroleum ether, benzene, toluene, etc.) and mixed solvents thereof. .

The total amount of the dye adsorbed is preferably 0.01 to 100 mmol per unit surface area (1 m ² ) of the porous semiconductor electrode substrate. The amount of the dye adsorbed on the semiconductor fine particles is preferably in the range of 0.01 to 1 mmol per 1 g of the semiconductor fine particles. With such an amount of dye adsorbed, a sufficient sensitizing effect in the semiconductor can be obtained. On the other hand, if the amount of the dye is too small, the sensitizing effect becomes insufficient, and if the amount of the dye is too large, the dye not adhering to the semiconductor floats and causes a reduction in the sensitizing effect. For the purpose of reducing the interaction such as aggregation between the dyes, a colorless compound may be added to the dyes and co-adsorbed to the semiconductor fine particles. Compounds effective for this purpose are compounds having surface-active properties and structures, such as steroid compounds having a carboxyl group (for example, chenodeoxycholic acid).

For the purpose of promoting the removal of excess dye, the surface of the semiconductor fine particles may be treated with an amine after adsorbing the dye. Preferred amines are pyridine,
4-t-butylpyridine, polyvinylpyridine and the like. When these are liquids, they may be used as they are, or may be used after being dissolved in an organic solvent.

(C) Charge Transfer Layer The charge transfer layer is a layer containing a charge transporting material having a function of replenishing an oxidized dye with electrons. In the present invention, it is necessary to ensure light transmittance, and the charge transfer layer is preferably thin. The preferred thickness of the charge transfer layer is 0.001 to 50 μm, more preferably 0.1 to 30 μm, particularly preferably
0.5 to 20 μm.

Examples of typical charge transporting materials that can be used in the present invention include, as an ion transporting material, a solution (electrolytic solution) in which redox couple ions are dissolved, and a redox couple solution in a polymer matrix gel. A so-called gel electrolyte, a molten salt electrolyte containing an oxidation-reduction counter ion, and a solid electrolyte. In addition to a charge transporting material involving ions, an electron transporting material or a hole (hole) transporting material may be used as a material relating to electric conduction in which carrier movement in a solid is involved. These can be used in combination.

(1) Molten Salt Electrolyte A molten salt electrolyte is most preferable for the purpose of the present invention from the viewpoint of achieving both photoelectric conversion efficiency and durability. When using a molten salt electrolyte for the photoelectric conversion element of the present invention, for example, WO95 / 18456
No., JP-A-8-259543, Electrochemistry, Vol. 65, No. 11, 923
Known iodine salts such as pyridinium salts, imidazolium salts, and triazolium salts described on page (1997) can be used.

The molten salt which can be preferably used includes those represented by any of the following formulas (Ya), (Yb) and (Yc).

[0067]

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In the general formula (Ya), Q _y1 is 5
Or an atomic group capable of forming a 6-membered aromatic cation. Q _y1 is preferably composed of one or more atoms selected from the group consisting of a carbon atom, a hydrogen atom, a nitrogen atom, an oxygen atom and a sulfur atom. The 5-membered ring formed by Q _{y 1} is preferably an oxazole ring, a thiazole ring, an imidazole ring, a pyrazole ring, an isoxazole ring, a thiadiazole ring, an oxadiazole ring or a triazole ring, and is preferably an oxazole ring, a thiazole ring or It is more preferably an imidazole ring, particularly preferably an oxazole ring or an imidazole ring. The 6-membered ring formed by Q _y1 is preferably a pyridine ring, a pyrimidine ring, a pyridazine ring, a pyrazine ring or a triazine ring, and more preferably a pyridine ring.

In the general formula (Yb), A _y1 represents a nitrogen atom or a phosphorus atom.

R in the general formulas (Ya), (Yb) and (Yc)
_{y1 to Ry6} each independently represent a substituted or unsubstituted alkyl group (preferably having 1 to 24 carbon atoms, which may be linear, branched, or cyclic; for example, methyl Group, ethyl group, propyl group, isopropyl group, pentyl group, hexyl group, octyl group, 2-ethylhexyl group, t-
Octyl, decyl, dodecyl, tetradecyl,
2-hexyldecyl group, octadecyl group, cyclohexyl group, cyclopentyl group, etc.) or a substituted or unsubstituted alkenyl group (preferably having 2 to 24 carbon atoms, which may be linear or branched, For example, a vinyl group or an allyl group), more preferably an alkyl group having 2 to 18 carbon atoms or an alkenyl group having 2 to 18 carbon atoms, and particularly preferably an alkyl group having 2 to 6 carbon atoms. .

Further, two or more of R _{y1 to} R _{y4 in} the general formula (Yb) may be linked to each other to form a non-aromatic ring containing A _y1, and R in the general formula (Yc) Two or more of _{y1 to Ry6} may be connected to each other to form a ring structure.

Q in the general formulas (Ya), (Yb) and (Yc)
_y1 and R _y1 to R _y6 may have a substituent, examples of preferred substituents, a halogen atom (F, Cl, Br, I
), A cyano group, an alkoxy group (such as a methoxy group and an ethoxy group), an aryloxy group (such as a phenoxy group), an alkylthio group (such as a methylthio group and an ethylthio group), an alkoxycarbonyl group (such as an ethoxycarbonyl group), and a carbonate group ( Ethoxycarbonyloxy group, etc.), acyl group (acetyl group, propionyl group, benzoyl group, etc.), sulfonyl group (methanesulfonyl group, benzenesulfonyl group, etc.), acyloxy group (acetoxy group, benzoyloxy group, etc.), sulfonyloxy group ( Methanesulfonyloxy group, toluenesulfonyloxy group, etc.), phosphonyl group (diethylphosphonyl group, etc.), amide group (acetylamino group, benzoylamino group, etc.), carbamoyl group (N, N-
Dimethylcarbamoyl group), alkyl group (methyl group,
Ethyl group, propyl group, isopropyl group, cyclopropyl group, butyl group, 2-carboxyethyl group, benzyl group, etc., aryl group (phenyl group, toluyl group, etc.), heterocyclic group (pyridyl group, imidazolyl group, furanyl group) etc),
Alkenyl groups (vinyl group, 1-propenyl group, etc.) and the like.

According to the general formula (Y-a), (Y-b) or (Y-c)
The compound represented by_y1Or R_y1~ R _y6Multimer through
May be formed.

These molten salts may be used alone or
May be used in combination.
Can be used in combination with a molten salt in which
Wear. As the anion to replace the iodine anion,
Halide ions (Cl-, Br-, etc.), NSC-, BF_Four−,
PF₆−, ClO_Four−, (CF_ThreeSO_Two)_TwoN−, (CF_ThreeCF_TwoSO_Two)_TwoN-, CF _ThreeS
O_Three−, CF_ThreeCOO−, Ph_FourB−, (CF_ThreeSO_Two)_ThreeExamples where C- etc. are preferred
(CF_ThreeSO_Two)_TwoN- or BF_Four-
Is more preferable. In addition, other iodine salts such as LiI are added.
You can also.

Specific examples of the molten salt preferably used in the present invention are shown below, but are not limited thereto.

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It is preferable not to use a solvent for the molten salt electrolyte. Although the solvent described below may be added, the content of the molten salt is preferably at least 50% by mass, particularly preferably at least 90% by mass, based on the entire electrolyte composition. Further, it is preferable that 50% by mass or more of the salt is an iodine salt.

It is preferable to add iodine to the electrolyte composition. In this case, the content of iodine is preferably 0.1 to 20% by mass, and more preferably 0.5 to 5% by mass based on the whole electrolyte composition. Is more preferred.

(2) Electrolyte When an electrolyte is used for the charge transfer layer, the electrolyte is an electrolyte,
It is preferable to be composed of a solvent and an additive. Book
The electrolyte of the invention is I_TwoAnd iodide combinations (iodide
Include LiI, NaI, KI, CsI, CaI_Two Such
Metal iodide or tetraalkyl ammonium
Iodide, pyridinium iodide, imidazolium
Iodine salts of quaternary ammonium compounds such as iodide
Etc.), Br _TwoAnd bromide (the bromide is L
iBr, NaBr, KBr, CsBr, CaBr_Two Such
Metal bromide or tetraalkylammonium
Quaternary ammonium such as romide and pyridinium bromide
Bromide salts), ferrocyanate salts
Ferricyanate and ferrocene-ferricinium ions
Which metal complex, sodium polysulfide, alkyl thiol
-Sulfur compounds such as alkyl disulfide, viologen
Dyes, hydroquinone-quinone and the like can be used.
You. Among them I_TwoAnd LiI and pyridinium iodide,
Quaternary ammonium compounds such as imidazolium iodide
In the present invention, an electrolyte containing a combination of various iodine salts is preferred.
No. The above-mentioned electrolytes may be used as a mixture.

The preferred electrolyte concentration is 0.1 M or more and 15 M or less, more preferably 0.2 M or more and 10 M or less. When iodine is added to the electrolyte, a preferable concentration of iodine is 0.01 M or more and 0.5 M or less.

The solvent used for the electrolyte may be a compound having low viscosity and improving ionic mobility, or having high dielectric constant and improving the effective carrier concentration to exhibit excellent ionic conductivity. desirable. Examples of such solvents include ethylene carbonate, carbonate compounds such as propylene carbonate, heterocyclic compounds such as 3-methyl-2-oxazolidinone, dioxane, ether compounds such as diethyl ether, ethylene glycol dialkyl ether, propylene glycol dialkyl ether, and polyethylene. Chain ethers such as glycol dialkyl ether and polypropylene glycol dialkyl ether, alcohols such as methanol, ethanol, ethylene glycol monoalkyl ether, propylene glycol monoalkyl ether, polyethylene glycol monoalkyl ether and polypropylene glycol monoalkyl ether, ethylene glycol, Propylene glycol, polyethylene glycol, polypropylene Glycol, polyhydric alcohols such as glycerin, acetonitrile, glutarodinitrile, methoxy acetonitrile, propionitrile, nitrile compounds such as benzonitrile, dimethyl sulfoxide, can be used aprotic polar substances such as sulfolane, water, and the like.

Further, according to the present invention, J. Am. Ceram. Soc.,
80 (12) 3157-3171 (1997), a basic compound such as ter-butylpyridine, 2-picoline or 2,6-lutidine can also be added. A preferred concentration range when a basic compound is added is 0.05M or more and 2M or less.

(3) Gel Electrolyte In the present invention, the electrolyte may be gelled (solidified) by a method such as addition of a polymer, addition of an oil gelling agent, polymerization containing a polyfunctional monomer, or crosslinking reaction of a polymer. it can. When gelling by polymer addition, use "Po
lymer Electrolyte Revews-1 and 2 "(JRMacCal
(co-edited by lum and CA Vincent, ELSEVIER APPLIED SCIENCE)
Can be used, and particularly, polyacrylonitrile and polyvinylidene fluoride can be preferably used. When gelling by adding an oil gelling agent, use J. Chem Soc. Japan, Ind. Chem.Sec.,
46,779 (1943), J. Am. Chem. Soc., 111,5542 (1989),
J. Chem. Soc., Chem. Commun., 1993, 390, Angew. Ch.
em. Int. Ed. Engl., 35, 1949 (1996), Chem. Lett., 19
96, 885, J. Chm. Soc., Chem. Commun., 1997, 545, but preferred compounds are those having an amide structure in the molecular structure.

(4) Hole transporting material In the present invention, a solid hole transporting material such as an organic or inorganic material or a combination thereof can be used instead of an ion-conductive electrolyte such as a molten salt.

(A) Organic hole transporting material The organic hole transporting material applicable to the present invention includes N, N'-
Diphenyl-N, N'-bis (4-methoxyphenyl)-(1,
1'-biphenyl) -4,4'-diamine (J. Hagen et al., Synth
etic Metal 89 (1997) 215-220), 2,2 ', 7,7'-tetrakis (N, N-di-p-methoxyphenylamine) 9,9'-spirobifluorene (Nature, Vol. 395, 8 Oct. 1998, p583-585 and WO97 / 10617), 1,1-bis {4- (di-p-tolylamino)
An aromatic diamine compound in which a tertiary aromatic amine unit of phenyl @ cyclohexane is linked (JP-A-59-194393), and 4,4-bis [(N-1-naphthyl) -N-phenylamino] biphenyl Aromatic amine containing two or more tertiary amines represented by two or more fused aromatic rings substituted with a nitrogen atom (JP-A-5-234681), and a derivative of triphenylbenzene having a starburst structure Aromatic triamine (U.S. Pat. No. 4,923,774, JP-A-4-3086)
No. 88), and aromatic diamines such as N, N′-diphenyl-N, N′-bis (3-methylphenyl)-(1,1′-biphenyl) -4,4′-diamine (US Pat. , 764, 625), α,
α, α ′, α′-Tetramethyl-α, α′-bis (4-di-p-tolylaminophenyl) -p-xylene (JP-A-3-269084), p-phenylenediamine derivative, whole molecule As a sterically asymmetric triphenylamine derivative (Japanese Unexamined Patent Publication No.
JP-A-129271), a compound in which a pyrenyl group is substituted with a plurality of aromatic diamino groups (JP-A-4-175395), and an aromatic diamine in which a tertiary aromatic amine unit is linked by an ethylene group (JP-A-4-264189) JP-A-5-25473, an aromatic diamine having a styryl structure (JP-A-4-290851), a benzylphenyl compound (JP-A-4-364153), and a tertiary amine linked by a fluorene group (JP-A-5-25473).
JP-A-5-320455), triamine compounds (JP-A-5-239455), and pisdipyridylaminobiphenyl (JP-A-5-320).
634), N, N, N-triphenylamine derivatives (JP-A-6-1972), aromatic diamines having a phenoxazine structure (JP-A-7-138562), and diaminophenylphenanthridine derivatives (JP-A-7-138562). The aromatic amines shown in, for example, Kaihei 7-252474) can be preferably used.

Further, α-octylthiophene and α, ω
-Dihexyl-α-octylthiophene (Adv. Mater. 199
7,9, N0.7, p557), hexadodecyldodecithiophene (Ang
ew.Chem. Int. Ed. Engl. 1995, 34, No. 3, p303-307),
2,8-dihexylanthra [2,3-b: 6,7-b '] dithiophene (J
Oligothiophene compounds such as ACS, Vol120, N0.4, 1998, p664-672), polypyrrole (K. Murakoshi et al.,; Chem.
Lett. 1997, p471), "Handbook of Organic Conduct
ive Molecules and Polymers Vol.1,2,3,4 "(by NALWA,
Polyacetylene and its derivatives, poly (p-phenylene) and its derivatives, poly (p-phenylenevinylene) and its derivatives, polythienylenevinylene and its derivatives, polythiophene and its derivatives, polyaniline and its Conductive polymers such as derivatives, polytoluidine and derivatives thereof can be preferably used.

Nature, Vol. 3
95, 8 Oct. 1998, p583-585, to add a compound containing a cation radical such as tris (4-bromophenyl) aminium hexachloroantimonate to control the dopant level, A salt such as Li [(CF ₃ SO ₂ ) ₂ N] may be added to control the potential of the oxide semiconductor surface (compensate for the space charge layer).

(B) Inorganic Hole Transport Material As the inorganic hole transport material, a p-type inorganic compound semiconductor can be used. The p-type inorganic compound semiconductor for this purpose preferably has a band gap of 2 eV or more,
Further, it is preferably 2.5 eV or more. Further, the ionization potential of the p-type inorganic compound semiconductor needs to be smaller than the ionization potential of the dye adsorption electrode from the condition that the holes of the dye can be reduced. Although the preferred range of the ionization potential of the p-type inorganic compound semiconductor varies depending on the dye used, it is generally preferably 4.5 eV or more and 5.5 eV or less, and more preferably 4.7 eV or more and 5.3 eV or less. Preferred p-type inorganic compound semiconductors are compound semiconductors containing monovalent copper, and examples of compound semiconductors containing monovalent copper include CuI, CuSCN, CuInSe ₂ , Cu (In, Ga)
Se ₂ , CuGaSe ₂ , Cu ₂ O, CuS, CuGaS ₂ , CuInS ₂ , CuAlSe _{2 and the} like. Among them, CuI and CuSCN are preferable, and CuI is most preferable. Other p-type inorganic compound semiconductors include GaP, NiO, CoO, FeO, Bi ₂ O ₃ , MoO ₂ , Cr ₂ O ₃
Etc. can be used.

Charge transfer containing p-type inorganic compound semiconductor
Preferred hole mobility of the layer is 10^-Fourcm ^Two/ Vsec or more 10^Fourcm^Two
/ Vsec or less, more preferably 10^-3cm^Two/ V ・ sec
More than 10^Threecm^Two/ V · sec or less. In addition, the charge transfer layer
Good conductivity is 10^-8S / cm or more 10 ^TwoS / cm or less
Preferably 10^-6It is not less than S / cm and not more than 10 S / cm.

(D) Transparent Counter Electrode An optically transparent conductive material and, if necessary, a transparent substrate are used for the counter electrode of the device of the present invention, similarly to the above-mentioned transparent conductive support. Examples of the conductive material used for the counter electrode transparent conductive layer include a thin film of metal (for example, platinum, gold, silver, copper, aluminum, magnesium, rhodium, indium, or the like), carbon, or a conductive metal oxide. Among them, preferred are conductive metal oxides having a transparent property (indium-tin composite oxide, tin oxide doped with fluorine, and the like). A preferred example of the transparent substrate is glass or plastic described in the section of the transparent conductive support, and the conductive agent is applied or vapor-deposited on the glass or plastic and used as a transparent counter electrode. The thickness of the counter electrode transparent conductive layer is not particularly limited, but is preferably 0.02 to 10 μm. When the counter electrode conductive layer is made of metal, the counter electrode conductive layer is made thin so as to be transparent. The lower the surface resistance of the counter electrode, the better. A preferred surface resistance range is 80
Ω / □ or less, and more preferably 20 Ω / □ or less. It is preferable to provide a metal lead in the same manner as the transparent conductive support.

(E) Other layers In order to prevent a short circuit between the counter electrode and the conductive support, or to prevent the conductive layer from being deteriorated by the electrolyte, a dense space is previously provided between the conductive support and the photosensitive layer. It is preferable to coat a semiconductor thin film layer as an undercoat layer. Preferred as the undercoat layer are TiO ₂ , SnO ₂ , Fe ₂ O ₃ , WO ₃ , ZnO, Nb ₂ O ₅
And more preferably TiO ₂ . The undercoat layer can be applied by, for example, a spray pyrolysis method or a sputtering method described in Electrochimica Acta 40, 643-652 (1995). The preferred thickness of the undercoat layer is
It is 5 to 1000 nm, more preferably 10 to 500 nm. Also,
A spacer layer for preventing electrical short circuit may be provided between the photosensitive layer and the counter electrode layer.

A functional layer such as a protective layer, an antireflection layer, or an ultraviolet absorbing layer may be provided on one or both of the conductive support serving as an electrode and the counter electrode. In order to form such a functional layer, in addition to a coating method such as a slide hopper method or an extrusion method, an evaporation method or a sticking method can be used depending on the material.

(F) Specific Example of Internal Structure of Photoelectric Conversion Element The internal structure of the photoelectric conversion element can take various forms according to the purpose. 2 to 5 show specific examples of the laminated structure.

FIG. 2 shows a photosensitive layer 20 made of a dye-sensitized porous semiconductor on one side of a colorless and transparent substrate 50 via a transparent conductive layer 10.
A charge transfer layer 30 is placed underneath, and a transparent substrate 50 carrying a light-transmitting counter electrode conductive layer 40 as a counter electrode is disposed as the lowermost layer, and these electrode layers are electrically connected to each other. This is a cell having a stacked structure. Transparent conductive layer 10
And 40 may be the same or different, and their substrates 50 may be the same or different (eg, a combination of glass and a transparent plastic film). The configuration in FIG. 3 is an example in which two types of photosensitive layers are used. The photosensitive layer 20a and the photosensitive layer 20b are coated on both sides of the colorless and transparent support 50 with the transparent conductive layer 10 interposed therebetween, and the charge transfer layer 30 is placed outside each of them. Tier 40
This is a configuration comprising two sets of photoelectric conversion elements on which a colorless and transparent support 50 provided with is provided. In this device, the two types of photosensitive layers may be photosensitive layers having different photosensitive wavelength regions or may be the same photosensitive layer having the same photosensitive wavelength region. The photoelectric conversion element shown in FIG. 4 is composed of two sets of photoelectric conversion elements as in FIG. 3, except that a transparent counter electrode is disposed inside, and a photosensitive layer and a transparent conductive support are disposed outside. FIG.
In this configuration, metal leads 11 are inserted into the transparent conductive support and the transparent counter electrode having the laminated structure described above. Although the width of the metal lead is emphasized in the figure for easy understanding, the occupied area (when viewed from the light incident side) is set to 20% or less.

Since the photoelectric conversion element of the present invention is transparent,
Light can be incident from either side, but in order to increase the power generation efficiency, it is preferable to arrange so that stronger light is incident from the transparent conductive support side (that is, the photosensitive layer side). For example, when applied to window glass, FIG.
In the configuration described above, it is preferable that the transparent conductive support is directed outdoors and the transparent counter electrode is directed indoors.

[2] Photovoltaic cell The photovoltaic cell of the present invention is such that the above-mentioned photoelectric conversion element works in an external circuit. It is preferable that the side surface of the photovoltaic cell is sealed with a polymer, an adhesive, or the like in order to prevent deterioration of components and volatilization of the contents. The external circuit itself connected to the conductive support and the counter electrode via a lead may be a known one. Among the photovoltaic cells, those that generate power under the sunlight in particular are solar cells. When the photoelectric conversion element of the present invention is applied to an outdoor solar cell, the transmitted light can be used for other systems (a heat storage system using infrared rays, lighting from a roof, and the like). The light-transmissive photoelectric conversion element of the present invention is used as a window glass, particularly when used as a window glass or as a film-like photoelectric conversion element to be attached to a conventional window glass, so that the window has appropriate transparency and light shielding properties. , A power generation function, a colorful interior function, etc.

[3] Optical Sensor The photoelectric conversion element of the present invention can also be used as a light transmission type optical sensor. In particular, a characteristic application is possible as a large-area sensor having an array of pixel units (that is, a position-sensitive sensor). For example, the photoelectric conversion element of the present invention is placed on a window of a building or a device or on the front of a device,
It is possible to monitor external light, brightness and its distribution while maintaining the light transmittance, and feed back this information to the control of the device to control a target event.

Further, by arranging a plurality of the above optical sensors as one pixel and two-dimensionally arranging them,
An image sensor can be formed. Thereby, two-dimensional image information can be obtained as an electric signal.

[0105]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to these examples. In this example, a transparent photovoltaic cell having the layer configuration shown in FIG. 5 was assembled according to the following procedure.

1. Production of transparent conductive support and transparent counter electrode One side of an 80 μm thick PET sheet supporting a SiO ₂ film is covered with a polyimide film mask provided with a lead pattern, and platinum is vapor-deposited through a mask by a vacuum vapor deposition method. A platinum lead pattern having a width of 0.4 mm and a thickness of 500 nm was prepared. A thin film of indium tin oxide (ITO) is uniformly coated on the entire surface by vacuum sputtering, and has a thickness of 200 nm, a sheet resistance of about 8Ω / □, and a light transmittance of 9 mm.
One side of the support provided with the lead pattern was coated with a conductive ITO film of 0% (wavelength 500 nm) to form a transparent conductive support (transparent counter electrode). The transparent conductive support (transparent counter electrode) had a transparent aperture ratio (a ratio of the area excluding the lead pattern to the entire area of the support) of 93%.

2. Preparation of Coating Solution Containing Titanium Dioxide Particles According to the production method described in the article of CJ Barbe et al., J. Am. Ceramic Soc. Was set at 230 ° C. to synthesize a titanium dioxide dispersion having a titanium dioxide concentration of 11% by weight. The average size of the primary particles of the obtained titanium dioxide particles was about 10 nm.
To this dispersion, 30% by weight of polyethylene glycol (average molecular weight: 20,000, manufactured by Wako Pure Chemical Industries) based on titanium dioxide was added and kneaded to obtain a viscous coating solution.

3. Preparation of Titanium Dioxide Electrode The transparent conductive support prepared in 1 above was coated with the coating solution of 2 above in a thickness of 50 μm by a doctor blade method on the ITO-coated side, dried at 25 ° C. for 60 minutes, and irradiated with ultraviolet rays. Lower 150
Heat treatment was performed at 60 ° C. for 60 minutes to form a thin layer of porous titanium dioxide on the PET sheet support. The coating amount of titanium dioxide was 4 g / m ² , and the film thickness was 3 μm.

4. Preparation of Dye Adsorption Solution As a sensitizing dye having absorption up to 750 nm on the long wavelength side and having an absorption peak in a blue to green region, Ru of the above-described specific example is used.
The complex dye (dye R-1) was dried with acetonitrile:
Concentration of 3 × 10 ^-4 mo in a mixed solvent of t-butanol (1: 1)
The dye was dissolved at 1 / L to prepare a dye adsorption solution.

5. Adsorption of Dye The above titanium dioxide electrode was immersed in the above dye solution for adsorption, and left at 40 ° C. for 3 hours with stirring. After the dye was adsorbed on the titanium dioxide fine particle layer in this way, the electrode was washed with acetonitrile to prepare a dye-sensitized titanium dioxide electrode.

6. Preparation of Photocell A part of the TiO ₂ layer of the dye-sensitized TiO ₂ electrode was scraped off to form a light receiving layer having a light receiving area of 12.0 cm ² (3.0 × 4.0 cm). In the light receiving surface, a platinum lead having a width of 0.4 mm was arranged at a pitch (period) of 5 mm in parallel with the 3.0 cm side of the light receiving surface. The titanium dioxide electrode and the transparent counter electrode (produced in 1.) are overlapped so that the photosensitive layer and the counter electrode transparent conductive layer face each other (so that the platinum leads overlap and face each other) according to the layer configuration of FIG. Was. Between these substrates, as a frame-shaped spacer, a thermocompression-bonding polyethylene film (thickness: 10 μm) was inserted so as to surround the photosensitive layer and overlapped, and the spacer portion was heated to 120 ° C. and laminated. The substrate was fixed by crimping. Further, the edge of the cell was sealed with an epoxy resin adhesive.

Next, Y7-2 / Y8-1 / iodine was passed through a small hole for injecting an electrolytic solution previously provided at a corner of the spacer.
= 15: 35: 1 (weight ratio), a room temperature molten salt electrolyte composition was infiltrated into the space between the electrodes at 50 ° C by utilizing the capillary phenomenon. All of the above-described cell assembling step and the electrolyte injecting step were performed in the above-described dry air at a dew point of −60 ° C. After the injection of the molten salt, the cell was suctioned for several hours under vacuum to deaerate the inside of the cell, and after completion, the small hole for injection was sealed with low-melting glass. As described above, the transparent photoelectric conversion element (transparent photocell) of the present invention using a transparent plastic as a support
Was fabricated (Example 3).

In the same manner, a long-wavelength dye R-10 having absorption in the visible region up to 900 nm was used as the sensitizing dye instead of R-1 used in the above examples, and the transparent photoelectric conversion of the present invention was carried out. An element was manufactured (Example 4). Furthermore, a photovoltaic cell of the present invention (Examples 1, 2, 5 to 9) and a photovoltaic cell for comparison were combined with those without a platinum lead, those with a changed pattern, and those with a changed titanium dioxide layer thickness as shown in Table 1. (Comparative Examples 1 and 2) were produced.

The photovoltaic cell manufactured in this manner has a wavelength of 650 nm.
Table 1 shows the results obtained by measuring the transmittance of the opening at the time of the measurement with a spectrophotometer equipped with an integrating sphere. In the cell using the dye R-1, the transmission color was dark red, and in the cell using R-10, the transmission color was dark green.

7. Measurement of photoelectric conversion efficiency A 500W xenon lamp (USHIO Inc.)
Correction filter (Oriel AM1.5direct)
And the incident light intensity on the battery is 100mW / cm ^TwoAdjust to
The simulated sunlight was irradiated. The fabricated photoelectrochemical battery
The electrical output of the instrument is measured with a current-voltage measuring device (Keithley source
Jar unit 238) and measure current-voltage characteristics.
Specified. Light energy conversion efficiency determined by this
(η) is described in Table 1 together with the contents of the cell components.
Was. The light energy conversion efficiency is not related to photoelectric conversion.
Calculated for the incident energy to all light receiving
You.

8. Visual sensory test of transparency To evaluate cell transparency and in-plane uniformity of transparency,
A test character array pattern is placed at a position 30 cm behind the cell, and the test pattern can be easily seen when viewed through the cell, from 1 (difficult to distinguish) to 3 (discriminable) to
The evaluation was performed on a scale of 5 (easy to determine). The results are shown in Table 1.
Described together.

[0117]

[Table 1]

From the results in Table 1, the following is clear. 1) In all of Examples 1 to 9, half or more of the maximum efficiency (6%) obtained by using the cell 7 with metal leads of the present invention, that is, 3 % Or better energy conversion efficiency. In contrast, in Comparative Examples 1 and 2, the conversion efficiency was low,
Visual transparency is also poor. 2) From the comparison between Example 3 and Example 9 and Comparative Example 1, even in a series of cells in which the photosensitive layer has a sufficient transmittance at 650 nm in the visible light region, even if the cell has a low transmission aperture ratio, the transmittance is visually observed. The rating is low, and at the same time the efficiency drops. In particular, in Comparative Example 1, compatibility between permeability and efficiency is no longer achieved. 3) When the transmittance measured at 650 nm is less than 20% as in Examples 7 and 8, the efficiency is sufficiently high but the transmittance is slightly deteriorated. In Example 8, the transmittance at 650 nm was 9%, which was lower than 10%.
It had a transmittance of 8%.

As described above, it can be seen from the results of the above examples that the light-transmitting photoelectric conversion element according to the conditions of the present invention provides good performance in terms of both light transmittance and conversion efficiency. Similar results were obtained when transparent glass was used as the substrate.

[0120]

According to the present invention, a light-transmitting photoelectric conversion element and a photovoltaic cell having excellent energy conversion efficiency are provided. This light-transmitting photoelectric conversion element can be applied to windows and interior goods having a power generation function.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a preferred configuration of a photoelectric conversion element of the present invention.

FIG. 2 is a cross-sectional view showing another example of the configuration of the photoelectric conversion element of the present invention.

FIG. 3 is a sectional view showing another example of the configuration of the photoelectric conversion element of the present invention.

FIG. 4 is a sectional view showing another example of the configuration of the photoelectric conversion element of the present invention.

FIG. 5 is a sectional view showing another example of the configuration of the photoelectric conversion element of the present invention.

[Explanation of symbols]

 10 ... Transparent conductive layer 11 ... Metal lead 20, 20a, 20b ... Photosensitive layer 21 ... Semiconductor fine particles 22 ... Dye 23 ... Charge transport material 30 ... Charge transfer layer 40 ..Transparent conductive layer 50 ... Transparent substrate 60 ... Undercoat layer

Claims (18)

[Claims] 1. A photoelectric conversion element comprising at least a transparent conductive layer, a semiconductor layer, a charge transfer layer, and a transparent counter electrode, wherein an area ratio of a light-transmitting portion of all light-receiving portions involved in photoelectric conversion is 80% or more. Wherein the light-transmitting portion has a wavelength region showing a light transmittance of 10% or more between wavelengths of 400 to 700 nm. 2. The transparent photoelectric conversion device according to claim 1, wherein an area ratio of a light-transmitting portion of all light-receiving portions involved in the photoelectric conversion is 90% or more and 99% or less. element. 3. The transparent photoelectric conversion element according to claim 1, wherein the transparent photoelectric conversion element has a metal lead in a portion that is not light-transmissive. 4. The transparent photoelectric conversion element according to claim 1, wherein the light transmitting portion has a wavelength of 500 to 700.
A transparent photoelectric conversion element having a wavelength region showing a light transmittance of 10% or more between nm. 5. The transparent photoelectric conversion element according to claim 1, wherein the light transmitting portion has a wavelength of 600 to 700.
A transparent photoelectric conversion element having a wavelength region showing a light transmittance of 10% or more between nm. 6. The transparent photoelectric conversion element according to claim 1, wherein said transparent photoelectric conversion element has a wavelength range in which said light transmittance is 20% or more. 7. The transparent photoelectric conversion element according to claim 1, wherein the thickness of the transparent conductive layer is 0.02 to 10
μm, the thickness of the semiconductor layer is 0.1 to 25 μm, the thickness of the charge transfer layer is 0.001 to 50 μm, and the thickness of the transparent counter electrode is 0.02 to 10 μm. Conversion element. 8. The transparent photoelectric conversion element according to claim 1, wherein the transparent conductive layer and the transparent counter electrode are:
A transparent photoelectric conversion element comprising a compound in which indium-tin composite oxide or tin oxide is doped with fluorine. 9. The transparent photoelectric conversion device according to claim 1, wherein said semiconductor layer is made of semiconductor fine particles. 10. The transparent photoelectric conversion device according to claim 1, wherein the semiconductor layer is dye-sensitized. 11. The transparent photoelectric conversion device according to claim 1, wherein said semiconductor layer is made of an n-type semiconductor. 12. The transparent photoelectric conversion element according to claim 11, wherein the n-type semiconductor is at least one kind selected from titanium oxide, zinc oxide, tin oxide, tungsten oxide and niobium oxide. A transparent photoelectric conversion element, which is an n-type semiconductor. 13. The transparent photoelectric conversion device according to claim 1, wherein the charge transfer layer is an ion-conductive electrolyte. 14. The transparent photoelectric conversion device according to claim 1, wherein said charge transfer layer is a room temperature molten salt electrolyte. 15. A photovoltaic cell comprising the transparent photoelectric conversion element according to claim 1. Description: 16. A solar cell comprising the transparent photoelectric conversion element according to claim 1. Description: 17. An optical sensor comprising the transparent photoelectric conversion element according to claim 1. Description: 18. A window glass having a power generation function, comprising a transparent photoelectric conversion element according to claim 1. Description: