JP5181550B2 - Photoelectric conversion element - Google Patents

Description

  The present invention relates to a photoelectric conversion element, and more particularly to a dye-sensitized photoelectric conversion element.

  Ruthenium (Ru) complexes are widely used as sensitizing dyes in dye-sensitized solar cells (Non-patent Document 1). However, since ruthenium itself is a rare and expensive metal element, development of a dye-sensitized solar cell using an organic dye that can be manufactured at low cost is in progress.

  On the other hand, as an approach for increasing the conversion efficiency of a dye-sensitized solar cell, it has been studied to increase the absorption of the sensitizing dye and to use light in a wider wavelength range. However, in order to use long-wavelength light in a dye-sensitized solar cell having a conventional configuration, it is necessary to select a semiconductor that matches the LUMO energy level of the sensitizing dye, and as a result, it is necessary to lower the voltage. come.

  As a measure for solving this problem, a tandem cell combining a plurality of semiconductor layers has been studied (Non-Patent Document 2).

When we focused on this technology and studied, high conversion efficiency was obtained by using a photoelectric conversion layer containing an amine derivative having a specific structure, and a tandem cell using a conventionally known ruthenium dye or the like. It has been found to be more stable and advantageous for long-term use.
B. O'Regan and M.M. Gratzel, Nature, 353, 737 (1991) FY2005 NEDO report on new technology for dye-sensitized solar cells (High-efficiency tandem solar cells) March 2006 Shinshu University

  An object of the present invention is to provide a photoelectric conversion element that has high conversion efficiency, is stable, and can withstand long-term use in a tandem cell in which a plurality of photoelectric conversion layers are combined.

  The above problem could be solved by the following configuration.

1. A photoelectric conversion element in which at least two kinds of semiconductor layers and an electrolyte layer are provided between the counter electrodes, and the at least two kinds of semiconductor layers are electrically connected in series , wherein at least one kind of the semiconductor layers is provided. Is a first layer formed by supporting a compound represented by the following (2) -13 or (3) -6 on a titanium oxide layer ,

The photoelectric conversion element, wherein at least one of the semiconductor layers other than the first layer is a second layer containing a phthalocyanine compound or a ruthenium complex .

2 . 2. The photoelectric conversion element as described in 1 above, wherein the second layer is a layer containing a p-type semiconductor.

3 . 2. The photoelectric conversion element as described in 1 above, wherein each of the at least two kinds of semiconductor layers is a layer containing an n-type semiconductor.

  9. 9. The photoelectric conversion element as described in any one of 1 to 8 above, wherein a semiconductor layer and an electrolyte layer on which a compound having the structure of the general formula (1) is supported are provided.

  According to the present invention, a photoelectric conversion element having high conversion efficiency, stability, and high durability could be provided.

  Hereinafter, the present invention will be described in more detail.

  The photoelectric conversion element basically includes an electrode made of a transparent conductive support at least on the incident light side, a photoelectric conversion layer (semiconductor layer) provided on the conductive support, an electrolyte layer, and the other side. It is comprised from the counter electrode.

  The photoelectric conversion element of the present invention will be described with reference to the drawings.

  FIG. 1 is a structural cross-sectional view of a tandem photoelectric conversion element having at least two types of photoelectric conversion layers (semiconductor layers) of the present invention.

  In FIG. 1A, counter electrodes are formed by electrodes 1, 2 and 3, 4 respectively, and photoelectric conversion layers 5 and 6 color-sensitized by the sensitizing dye of the present invention are formed on electrodes 1 and 3, respectively. In addition, electrolyte layers 7 and 8 are provided between the counter electrodes, and cell A and cell B are formed. In each photoelectric conversion layer, an NN pole series tandem using an n-type semiconductor is formed.

  Since the incident light indicated by the arrow is transmitted, at least the electrodes 1, 2, and 3 are electrodes made of a transparent conductive support, and the electrode 4 may be transparent or opaque reflective electrode. good.

  In FIG. 1 (b), photoelectric conversion layers 5 and 6 are formed on the electrodes 1 and 3, a common electrode 2 'is provided therebetween, and electrolyte layers 7 and 8 are formed between the electrodes. . The electrode 2 'is connected with electrodes formed on both sides. An example of an NN pole parallel tandem in which n-type semiconductors are used for the photoelectric conversion layers and cells A and B are connected in parallel is shown.

  On the other hand, in FIG. 1C, photoelectric conversion layers 5 and 6 are formed on the electrodes 1 and 3, and each photoelectric conversion layer is formed with a counter electrode using an n-type semiconductor or a p-type semiconductor. An example of an NP pole series tandem in which an electrolyte layer is formed between electrodes is shown.

Specific examples of the p-type semiconductor used for the photoelectric conversion layer include Cu ₂ O, Cr ₂ O ₃ , Mn ₂ O ₃ , FeOx (x to 0.1), NiO, CoO, Pr ₂ O ₃ , Ag. ₂ O, MoO ₂ , Bi ₂ O _{3 and the} like can be mentioned.

Specific examples of the n-type semiconductor used for the photoelectric conversion layer include ZnO, TiO ₂ , SnO ₂ , ThO ₂ , V ₂ O ₅ , Nb ₂ O ₅ , Ta ₂ O ₅ , MoO ₃ , WO ₃ and MnO. ₂ etc. are mentioned.

  These semiconductors can be obtained as a powder, and a porous semiconductor layer can be formed by dispersing in a solvent and, if necessary, applying and drying on an electrode plate using a binder, followed by sintering.

  By using the compound having the structure represented by the general formula (1) as the sensitizing dye in the semiconductor layer thus formed, the photoelectric conversion element of the present invention can be obtained, and the tandem photoelectric conversion element The problem of conversion efficiency and durability could be solved.

In the general formula (1), examples of the alkyl group represented by R ₁ and R ₂ include a methyl group, an ethyl group, a butyl group, an octyl group, a nonyl group, an octadecyl group, and the like. For example, a phenyl group, a naphthyl group, etc. can be mentioned, As a heterocyclic group, a pyrrole group, a pyrazole group, a thiazole group, an imidazole group, a triazole group, a pyridyl group, a morpholyl group etc. can be mentioned, for example. R ₁ and R ₂ may be connected to each other to form a cyclic structure.

Examples of the aryl group represented by Ar ₁ include a phenyl group and a naphthyl group. Examples of the heterocyclic group include a pyrrole group, a pyrazole group, a thiazole group, an imidazole group, a triazole group, a pyridyl group, and morpholyl. Groups and the like. Ar ₁ may be linked to R ₁ and R ₂ to form a cyclic structure.

  These groups may further have a substituent. Examples of the substituent include an alkyl group, an alkenyl group, an aryl group, a heterocyclic group, a halogen atom, a hydroxy group, a mercapto group, an amino group, a cyano group, A carboxyl group, a sulfo group, etc. can be mentioned.

  X represents an acidic group or an organic group having an acidic group, and examples of the acidic group include a carboxyl group, a sulfo group, a phosphono group, a hydroxy group, and a mercapto group.

Examples of the organic group to which these acidic groups are bonded include an alkyl group, an alkenyl group, an aryl group, and a heterocyclic group, and the same as the alkyl group, aryl group, and heterocyclic group mentioned in R ₁ and R ₂ . The group can be mentioned.

  n represents an integer of 1 to 8, preferably 2 or more, and particularly preferably 2 or 3.

  Particularly preferred examples of X include —CH═C (CN) COOH, — (heterocycle) —COOH and the like.

In the general formula (1), R ₁ and R ₂ are each preferably a substituted or unsubstituted aryl group or heterocyclic group.

In the general formula (1), it is preferable that at least one substituent of R ₁ , R ₂ , Ar ₁ , and X contains an alkyl group having 6 or more carbon atoms.

  Specific examples of the compound represented by the general formula (1) are shown below, but the present invention is not limited to these compounds.

  The sensitizing dye of the present invention can be prepared by a general synthesis method.

  For example, the method of obtaining the sensitizing dye which introduce | transduced the acidic group by making cyanoacetic acid react with the formyl body which does not have an acidic group is mentioned.

  The sensitizing dye of the present invention thus obtained is sensitized by being contained in a semiconductor, and the effects described in the present invention can be achieved. Here, the inclusion of the sensitizing dye in the semiconductor means that the semiconductor is adsorbed on the surface of the semiconductor, and when the semiconductor has a porous structure such as a porous structure, the semiconductor has a porous structure filled with the sensitizing dye. An embodiment is mentioned.

Further, the total content of the sensitizing dye of the present invention per 1 m ^{2 of the} photoelectric conversion layer is preferably in the range of 0.01 mmol to 100 mmol, more preferably 0.1 mmol to 50 mmol, particularly preferably 0.8. 5 to 20 mmol.

  When the sensitizing treatment is performed using the sensitizing dye of the present invention, the sensitizing dye may be used alone or in combination, and other compounds (for example, US Pat. No. 4,684). No. 5,537, No. 4,927,721, No. 5,084,365, No. 5,350,644, No. 5,463,057, No. 5,525. , 440, JP-A-7-249790, JP-A-2000-150007, etc.) can also be used as a mixture. Specifically, phthalocyanine, azo pigments, squalium, various chelates, etc. are used. By using compounds having different absorption wavelengths in at least two types of photoelectric conversion layers, the dye used can be used to utilize light in a wider range of wavelengths, and a photoelectric conversion element with high conversion efficiency is expected.

  In particular, when the tandem photoelectric conversion element of the present invention is used as a solar cell, two or more kinds of dyes having different absorption wavelengths are used so that the wavelength range of photoelectric conversion can be made as wide as possible to effectively use sunlight. However, it is necessary to use the sensitizing dye of the present invention for at least one photoelectric conversion element.

  In order to include the sensitizing dye of the present invention in the semiconductor layer, a method in which the sensitizing dye is dissolved in an appropriate solvent (such as ethanol) and a well-dried photoelectric conversion layer is immersed in the solution for a long time is generally used. is there.

  When using a plurality of sensitizing dyes of the present invention in combination, or in combination with other sensitizing dyes, a sensitizing dye mixed solution may be prepared and used. It is also possible to prepare separate solutions for these sensitizing dyes and immerse them in each solution in turn. When preparing a separate solution for each sensitizing dye and immersing in each solution in order, the effects described in the present invention can be obtained regardless of the order in which the sensitizing dye is included in the photoelectric conversion layer. Can be obtained. Further, it may be produced by mixing semiconductor fine particles adsorbed with the sensitizing dye alone.

  Further, details of the sensitizing treatment of the photoelectric conversion layer according to the present invention will be specifically described in the photoelectric conversion element described later.

  In the case of a photoelectric conversion layer having a high porosity, the adsorption treatment of a sensitizing dye or the like must be completed before water is adsorbed on the semiconductor thin film and in the voids inside the semiconductor thin film due to moisture, water vapor, etc. Is preferred.

(Conductive support)
As the conductive support used in the photoelectric conversion element of the present invention, a conductive support having a structure in which a conductive material is provided on a conductive material such as a metal plate or a non-conductive material such as a glass plate or a plastic film is used. be able to. Examples of materials used for the conductive support include metal (for example, platinum, gold, silver, copper, aluminum, rhodium, indium) or conductive metal oxide (for example, indium-tin composite oxide, tin oxide doped with fluorine) And carbon). The thickness of the conductive support is not particularly limited, but is preferably 0.3 to 5 mm.

  The conductive support is preferably substantially transparent, and substantially transparent means that the light transmittance is 10% or more, more preferably 50% or more, and 80 % Or more is most preferable. In order to obtain a transparent conductive support, it is preferable to provide a conductive layer made of a conductive metal oxide on the surface of a glass plate or a plastic film. When a transparent conductive support is used, light is preferably incident from the support side.

The conductive support has a surface resistance of preferably 50 Ω / cm ² or less, and more preferably 10 Ω / cm ² or less.

<< Production of photoelectric conversion layer >>
A method for manufacturing a photoelectric conversion layer according to the present invention will be described.

  When the semiconductor of the photoelectric conversion layer according to the present invention is in the form of particles, the photoelectric conversion layer is preferably produced by applying or spraying the semiconductor to a conductive support. In addition, when the semiconductor according to the present invention is in a film form and is not held on the conductive support, it is preferable to produce a photoelectric conversion layer by bonding the semiconductor onto the conductive support.

  As a preferable embodiment of the photoelectric conversion layer according to the present invention, a method of forming by baking using fine particles of semiconductor on the conductive support can be mentioned.

  When the semiconductor according to the present invention is produced by firing, the sensitizing treatment (adsorption, filling into the porous layer, etc.) of the semiconductor using a sensitizing dye is preferably performed after firing. It is particularly preferable to perform the compound adsorption treatment quickly after the firing and before the water is adsorbed to the semiconductor.

  Hereinafter, a method for forming a photoelectric conversion layer, which is preferably used in the present invention, by baking using semiconductor fine powder will be described in detail.

(Preparation of coating liquid containing semiconductor fine powder)
First, a coating solution containing fine semiconductor powder is prepared. The finer the primary particle diameter of the semiconductor fine powder, the better. The primary particle diameter is preferably 1 to 5000 nm, more preferably 2 to 50 nm. The coating liquid containing the semiconductor fine powder can be prepared by dispersing the semiconductor fine powder in a solvent. The semiconductor fine powder dispersed in the solvent is dispersed in the form of primary particles. The solvent is not particularly limited as long as it can disperse the semiconductor fine powder.

  Examples of the solvent include water, an organic solvent, and a mixed solution of water and an organic solvent. As the organic solvent, alcohols such as methanol and ethanol, ketones such as methyl ethyl ketone, acetone and acetyl acetone, hydrocarbons such as hexane and cyclohexane, and the like are used. A surfactant and a viscosity modifier (polyhydric alcohol such as polyethylene glycol) can be added to the coating solution as necessary. The range of the metal compound semiconductor fine powder concentration in the solvent is preferably 0.1 to 70% by mass, more preferably 0.1 to 30% by mass.

(Application of semiconductor fine powder-containing coating solution and baking treatment of the formed photoelectric conversion layer)
The coating solution containing the metal compound semiconductor fine powder obtained as described above is applied or sprayed onto a conductive support, dried, etc., and then baked in air or in an inert gas to be conductive. A metal compound semiconductor layer (semiconductor film) is formed on the support.

  The film obtained by applying and drying the coating liquid on the conductive support is composed of an aggregate of semiconductor fine particles, and the particle size of the fine particles corresponds to the primary particle size of the semiconductor fine powder used. is there.

  Thus, the semiconductor fine particle layer formed on the conductive layer such as the conductive support is weak in bonding strength with the conductive support and fine particles, and has low mechanical strength. The semiconductor fine particle layer is baked to increase the mechanical strength and form a semiconductor layer that is strongly fixed to the substrate.

  In the present invention, the photoelectric conversion layer may have any structure, but is preferably a porous structure film (also referred to as a porous layer having voids).

  Here, the porosity of the photoelectric conversion layer according to the present invention is preferably 10% by volume or less, more preferably 8% by volume or less, and particularly preferably 0.01% by volume to 5% by volume. Note that the porosity of the photoelectric conversion layer means a porosity that is penetrating in the thickness direction of the dielectric, and can be measured using a commercially available device such as a mercury porosimeter (Shimadzu porer 9220 type).

  As for the film thickness of the photoelectric converting layer used as the baked material film | membrane which has a porous structure, 10 nm or more is preferable at least, More preferably, it is 100-10000 nm.

  From the viewpoint of appropriately preparing the actual surface area of the fired product film during the firing treatment and obtaining a fired product film having the above porosity, the firing temperature is preferably lower than 1000 ° C, more preferably in the range of 200 to 800 ° C. Especially preferably, it is the range of 300-800 degreeC.

  The ratio of the actual surface area to the apparent surface area can be controlled by the particle size, specific surface area, firing temperature, etc. of the semiconductor fine particles. In addition, for the purpose of increasing the surface area of the semiconductor particles after heating, increasing the purity in the vicinity of the semiconductor particles, and increasing the efficiency of electron injection from the dye into the semiconductor particles, for example, chemical plating using a titanium tetrachloride aqueous solution or three An electrochemical plating process using a titanium chloride aqueous solution may be performed.

(Semiconductor sensitization treatment)
As described above, the semiconductor sensitization treatment is performed by dissolving the sensitizing dye of the present invention in an appropriate solvent and immersing the conductive support obtained by firing the semiconductor in the solution. In that case, it is preferable to remove the bubbles in the film by subjecting the conductive support formed by firing the photoelectric conversion layer to pressure reduction treatment or heat treatment in advance. Such treatment allows the sensitizing dye of the present invention to enter deep inside the photoelectric conversion layer (semiconductor film), and is particularly preferable when the photoelectric conversion layer (semiconductor film) is a porous structure film.

  The solvent used for dissolving the sensitizing dye of the present invention is not particularly limited as long as it can dissolve the compound and does not dissolve the semiconductor or react with the semiconductor. However, in order to prevent moisture and gas dissolved in the solvent from entering the semiconductor film and hindering sensitizing treatment such as adsorption of the sensitizing dye, it is preferable to deaerate and purify in advance.

  Solvents preferably used in dissolving the sensitizing dye include alcohol solvents such as methanol, ethanol and n-propanol, ketone solvents such as acetone and methyl ethyl ketone, diethyl ether, diisopropyl ether, tetrahydrofuran and 1,4-dioxane. Ether solvents, halogenated hydrocarbon solvents such as methylene chloride, 1,1,2-trichloroethane, and particularly preferably methanol, ethanol, acetone, methyl ethyl ketone, tetrahydrofuran, and methylene chloride.

(Tensing temperature and time)
The time for immersing the conductive support obtained by baking the semiconductor in the solution containing the sensitizing dye of the present invention is such that the sensitizing dye enters the photoelectric conversion layer (semiconductor layer) deeply so that adsorption or the like proceeds sufficiently, and the semiconductor Is preferably sufficiently sensitized. Further, from the viewpoint of suppressing degradation of the sensitizing dye in the solution and preventing the degradation product from interfering with the adsorption of the compound, it is preferably 3 to 48 hours under 25 ° C., more preferably 4 to 4 hours. 24 hours. This effect is particularly remarkable when the semiconductor film is a porous structure film. However, the immersion time is a value at 25 ° C., and is not limited to the above when the temperature condition is changed.

  In soaking, the solution containing the sensitizing dye of the present invention may be heated to a temperature that does not boil as long as the dye does not decompose. A preferable temperature range is 10 to 100 ° C., more preferably 25 to 80 ° C., but this is not the case when the solvent boils in the temperature range as described above.

"Electrolytes"
Next, the electrolyte used in the present invention will be described.

In the photoelectric conversion element of the present invention, an electrolyte is filled between the counter electrodes to form an electrolyte layer. A redox electrolyte is preferably used as the electrolyte. Here, examples of the redox electrolyte include I ⁻ / I ³⁻ , Br ⁻ / Br ^{3 −} , and quinone / hydroquinone. Such a redox electrolyte can be obtained by a conventionally known method. For example, an I ⁻ / I ³⁻ type electrolyte can be obtained by mixing iodine ammonium salt and iodine. The electrolyte layer is composed of dispersions of these redox electrolytes. These dispersions are dispersed in liquid electrolytes when they are solutions, solid polymer electrolytes and gel substances when dispersed in polymers that are solid at room temperature. It is called a gel electrolyte. When a liquid electrolyte is used as the electrolyte layer, an electrochemically inert solvent is used as the solvent, for example, acetonitrile, propylene carbonate, ethylene carbonate, or the like is used. Examples of the solid polymer electrolyte include the electrolyte described in JP-A No. 2001-160427, and examples of the gel electrolyte include the electrolyte described in “Surface Science” Vol. 21, No. 5, pages 288 to 293.

《Counter electrode》
The counter electrode used in the present invention will be described.

A counter electrode provided opposite to the photoelectric conversion layer (semiconductor layer) conductive support is formed as described above is as long as it has conductivity, but any conductive material is used, I ^3- ions It is preferable to use a catalyst having a catalytic ability to cause oxidation or other redox ion reduction reaction at a sufficient speed. Examples of such a material include a platinum electrode, a surface of a conductive material subjected to platinum plating or platinum deposition, rhodium metal, ruthenium metal, ruthenium oxide, and carbon.

[Solar cell]
A solar cell is mentioned as a preferable embodiment of the photoelectric conversion element of the present invention.

  The solar cell is an aspect of the photoelectric conversion element of the present invention, and has a structure that allows optimum design and circuit design to sunlight and optimum photoelectric conversion when sunlight is used as a light source. . That is, it has a structure in which sunlight can be applied to a dye-sensitized metal compound semiconductor. When constituting the solar cell of the present invention, it is preferable that the photoelectrode, the electrolyte layer and the counter electrode are housed in a case and sealed, or the whole is sealed with resin.

  When the solar cell of the present invention is irradiated with sunlight or an electromagnetic wave equivalent to sunlight, the sensitizing dye according to the present invention adsorbed on the metal compound semiconductor absorbs the irradiated light or electromagnetic wave and excites it. Electrons generated by excitation move to the metal compound semiconductor, and then move to the counter electrode via the conductive support, thereby reducing the redox electrolyte of the charge transfer layer. On the other hand, the sensitizing dye according to the present invention in which electrons are transferred to a semiconductor is an oxidant, but is reduced by the supply of electrons from the counter electrode via the redox electrolyte of the electrolyte layer, and the original sensitizing dye is reduced. At the same time, the redox electrolyte of the charge transfer layer is oxidized and returned to a state where it can be reduced again by the electrons supplied from the counter electrode. In this way, electrons flow, and a solar cell using the photoelectric conversion element of the present invention can be configured.

Reference Examples 1-7, Example 8, Reference Examples 9, 10, Example 11
A commercially available titanium oxide paste (particle size 18 nm) was applied to a fluorine-doped tin oxide (FTO) conductive glass substrate by the doctor blade method, heated at 60 ° C. for 10 minutes to dry the paste, and then at 500 ° C. for 30 minutes. Firing was performed to form a titanium oxide layer having a thickness of 5 μm after sintering. Next, the dyes listed in Table 1 were dissolved in ethanol to prepare a 3 × 10 ⁻⁴ M solution. The FTO glass substrate on which the titanium oxide was sintered was immersed in this solution at room temperature for 16 hours, and dye adsorption treatment was performed to obtain a first photoelectric conversion electrode (N pole).

Next, a tin oxide paste in which SnO ₂ fine particles (particle size of about 20 nm) are dispersed is prepared, applied onto an electrode substrate made of SnO ₂ conductive glass by a doctor blade method, dried, and then baked at 500 ° C. for 30 minutes. And a porous SnO ₂ photoelectric conversion layer having a thickness of 5 μm was obtained. This was immersed in an ethanol solution of 3 × 10 ⁻⁴ M zinc phthalocyanine (compound A) to produce a second photoelectric conversion electrode (N pole). As the electrolytic solution, a 2-methylpropionitrile solution containing lithium iodide 0.4M, iodine 0.05M, 4- (t-butyl) pyridine 0.5M, two photoelectric conversion electrodes prepared earlier, An NN pole series tandem photoelectric conversion cell shown in FIG. 1A was produced using an FTO electrode on which platinum was supported by sputtering.

  Compound A was obtained by the following preparation method.

[Preparation of Compound A]
Compound A was synthesized according to a method described in a known document (Angew. Chem. Int. Ed., (46), 373-376, (2007)) shown by the following reaction route.

Comparative Example 1
A single cell was fabricated with the first photoelectric conversion electrode (N pole) of Reference Example 1 and an FTO electrode carrying platinum.

Comparative Example 2
In Reference Example 1, an NN-pole series tandem photoelectric conversion cell was produced in the same manner as Reference Example 1 except that the dye described in Table 1 was replaced with a ruthenium dye.

Reference Example 12
As in Reference Example 1, the first photoelectric conversion layer (N pole) was used, and the FTO glass substrate sintered with titanium oxide was immersed in an ethanol solution of ruthenium dye, so that the third photoelectric conversion electrode (N pole) was used. Then, a platinum mesh electrode was arranged between the first and third photoelectric conversion electrodes, and an NN pole parallel tandem photoelectric conversion cell as shown in FIG. 1B was manufactured.

Comparative Example 3
In Reference Example 12, a NN pole parallel tandem photoelectric conversion cell was produced in the same manner as in Example 12 except that the dye of the first photoelectric conversion layer was changed to the following ruthenium dye.

Reference Example 13
The first photoelectric conversion layer (N pole) was used as in Reference Example 1, while the nickel oxide sintered FTO was sintered in the same manner by replacing the titanium oxide of the FTO glass substrate sintered with the titanium oxide with nickel oxide. A glass substrate was prepared. Using the nickel oxide sintered substrate of the lake, it was immersed in the ethanol solution of the commercially available ruthenium pigment | dye, and the 4th photoelectric conversion electrode (P pole) was formed. 1st photoelectric conversion electrode (N pole) and 4th photoelectric conversion electrode (P pole) were made to oppose, and the photoelectric conversion cell of an NP pole series tandem as shown in FIG.1 (c) was produced.

Comparative Example 4
In Reference Example 13, an NP pole series tandem photoelectric conversion cell was produced in the same manner as Reference Example 13 except that the dye of the first photoelectric conversion layer was changed to ruthenium dye.

  The following evaluation was performed using the photoelectric conversion cell produced as described above.

Ruthenium dye: Dithiocyanato-bis (2,2′-bipyridyl-4,4′-dicarboxylate) ruthenium [Evaluation]
After the first to fourth photoelectric conversion electrodes were exposed for 20 minutes in an ozone atmosphere of 13 ppm, photoelectric conversion cells were similarly produced, and changes in power generation characteristics with and without ozone treatment were compared.

In the evaluation, photoelectric conversion characteristics were measured under the condition that a semiconductor electrode was covered with a 5 × 5 mm ² mask under irradiation of a xenon lamp having an intensity of 100 mW / cm ² . That is, the current-voltage characteristics of the photoelectric conversion elements of the examples were measured at room temperature using an IV tester, and the short circuit current (Isc), the open circuit voltage (Voc), and the form factor (FF) were measured. The photoelectric conversion efficiency (η (%)) was determined from these. In addition, the photoelectric conversion efficiency ((eta) (%)) of the solar cell was computed based on the following formula (A).

η = 100 × (Voc × Isc × FF) / P (A)
Here, P is the incident light intensity [mW / cm ⁻² ], Voc is the open circuit voltage [V], Isc is the short-circuit current density [mA · cm ⁻² ], F.V. F. Indicates a form factor.

  Table 1 shows the evaluation of the characteristics of ozone exposure.

  It can be seen that the dye of the present invention is superior in stability to ozone as compared with the ruthenium dye of the comparative example, and exhibits a good conversion efficiency by tandemization.

An example of the tandem photoelectric conversion element of the present invention is shown.

Explanation of symbols

1, 2, 3, 4 Electrodes 5, 6 Photoelectric conversion layer 7, 8 Electrolyte layer

Claims (3)

A photoelectric conversion element in which at least two kinds of semiconductor layers and an electrolyte layer are provided between the counter electrodes, and the at least two kinds of semiconductor layers are electrically connected in series ,
At least one of the semiconductor layers is a first layer formed by supporting a compound represented by the following (2) -13 or (3) -6 on a titanium oxide layer ,
The photoelectric conversion element, wherein at least one of the semiconductor layers other than the first layer is a second layer containing a phthalocyanine compound or a ruthenium complex . The photoelectric conversion element according to claim 1 , wherein the second layer is a layer containing a p-type semiconductor. The photoelectric conversion element according to claim 1 , wherein each of the at least two types of semiconductor layers is a layer containing an n-type semiconductor.