JP2010009786A - Dye sensitized solar cell, and dye sensitized solar cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dye sensitized solar cell and a dye sensitized solar cell module exhibiting high performance. <P>SOLUTION: The dye sensitized solar cell includes a conductive support equipped with a transparent conductive layer on a support, a porous photoelectric transducing layer of adsorbing dye on a porous semiconductor layer on the transparent conductive layer of the conductive support, a carrier transport layer, and a counter electrode side support. It is characterized in that the porous includes at least three layers, and refractive indexes of a porous semiconductor layer formed in a place most nearest and a porous semiconductor layer formed in a place most farthest are higher than a refractive index of a porous semiconductor layer formed in between with respect to an incident direction of light. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a dye-sensitized solar cell and a dye-sensitized solar cell module.

  Solar cells that can convert sunlight into electric power are attracting attention as an energy source to replace fossil fuels. Currently, solar cells that have been partially put into practical use include solar cells using crystalline silicon substrates and amorphous thin-film silicon solar cells.

  As a new type of solar cell, Patent Document 1 discloses a dye-sensitized solar cell to which photoinduced electron transfer of a metal complex is applied. These dye-sensitized solar cells are composed of a porous photoelectric conversion layer composed of a porous semiconductor layer adsorbing a dye, a carrier transport layer, and a pair of electrodes. A bipyridine ruthenium complex is adsorbed on the porous semiconductor layer as a sensitizing dye having an absorption spectrum in the visible light region.

  In these batteries, when light is irradiated to a porous photoelectric conversion layer composed of a porous semiconductor layer and a dye, electrons in the dye are excited, and the electrons move to the counter electrode through an external circuit. The electrons that have moved to the counter electrode are carried by the ions in the electrolyte that is the carrier transport layer, and return to the porous photoelectric conversion layer. Such a process is repeated to extract electric energy.

  However, the present situation is that the dye-sensitized solar cell has a lower photoelectric conversion efficiency than the silicon solar cell.

  In Patent Document 2, it is possible to improve the conversion efficiency by providing a high refractive material thin film on a support, forming a porous semiconductor electrode thereon, and depositing a light reflecting particle layer thereon. A possible technique is disclosed.

  However, in this technique, since the high refractive material thin film is formed on the support, the dye is not adsorbed on the film, and light absorption in the film cannot be expected. Therefore, the incident light is absorbed only by the porous semiconductor electrode, which is a factor of reducing the conversion efficiency.

Patent Document 3 discloses a dye-sensitized solar cell using oxide particles in which a core particle of a high refractive material is coated with a shell of a low refractive material. This is a technique in which the efficiency is improved by reflection with a highly refractive material and reflection between coated oxide particles. However, sufficient reflectivity cannot be obtained with only this single layer of film, and sufficient performance cannot be obtained with a single cell of a dye-sensitized solar cell.
Japanese Patent No. 2664194 JP-A-10-255863 JP 2002-110261 A

  In order to solve the above problems, the present invention provides a dye-sensitized solar cell and a dye-sensitized solar cell module that exhibit high performance.

  The dye-sensitized solar cell of the present invention includes a conductive support provided with a transparent conductive layer on a support, a porous material in which a dye is adsorbed on a porous semiconductor layer on the transparent conductive layer of the conductive support. In a dye-sensitized solar cell including a photoelectric conversion layer, a carrier transport layer, and a counter electrode side support, the porous semiconductor layer is composed of at least three layers, and is formed at a position closest to the incident direction of light. It is characterized in that the refractive index of the porous semiconductor layer formed farthest from the porous semiconductor layer is higher than the refractive index of the porous semiconductor layer formed therebetween.

  The porous semiconductor layer is composed of three layers, and is formed in the order of the first porous semiconductor layer, the second porous semiconductor layer, and the third porous semiconductor layer in order from the incident direction of light, and the second The refractive index of the first and third porous semiconductor layers is preferably larger than the refractive index of the porous semiconductor layer.

  It is preferable that the refractive index of said 1st porous semiconductor layer and the 3rd porous semiconductor layer is 0.1 or more larger than the refractive index of a 2nd porous semiconductor layer.

The first porous semiconductor layer is preferably rutile titanium oxide.
The second porous semiconductor layer is preferably anatase-type titanium oxide or strontium titanate.

The third porous semiconductor layer is preferably rutile titanium oxide.
Moreover, according to this invention, the dye-sensitized solar cell module using the said dye-sensitized solar cell is provided.

  By using the present invention, a dye-sensitized solar cell and a dye-sensitized solar cell module with improved conversion efficiency can be provided.

  Preferred embodiments of the present invention will be described with reference to the drawings. In addition, this embodiment is an example and implementation with a various form is possible within the scope of the present invention.

<Dye-sensitized solar cell>
FIG. 1 shows a cross-sectional view of a dye-sensitized solar cell 8 (hereinafter also referred to as “solar cell”) of the present invention. The dye-sensitized solar cell 8 of the present invention includes a conductive support 3 having a transparent conductive layer 2 on a support 1, and a porous semiconductor layer 11 on the transparent conductive layer 2 of the conductive support 3. In the dye-sensitized solar cell 8 including the porous photoelectric conversion layer 31 on which the dye is adsorbed, the carrier transport layer 4, and the counter electrode support 7, the porous semiconductor layer 11 includes materials having different refractive indexes. It is characterized by comprising a plurality of porous semiconductor layers. Further, the carrier transport layer 4 is filled between the conductive support 3 and the counter electrode support 7, and the side surface is sealed with the spacer 21 and the sealing material 22.

<Support>
If the support 1 in this embodiment is a material generally used as a support of a dye-sensitized solar cell, the material will not be specifically limited. For example, a heat-resistant film made of a flexible film made of a glass substrate such as soda glass, fused silica glass, or crystalline quartz glass, or a material such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or Teflon (registered trademark). Can be used. In addition, it is preferable that any one of the support body 1 and the counter electrode side support body 7 has a light transmittance. However, it is sufficient that it transmits light having a wavelength having an effective sensitivity to at least a sensitizing dye described later, and is not necessarily required to be transparent to light having all wavelengths.

  Moreover, the support body 1 can be utilized when attaching the completed solar cell to another structure. That is, the peripheral part of the support body 1 such as a glass substrate can be easily attached to another support body 1 using metal processed parts and screws.

<Transparent conductive layer>
The transparent conductive layer 2 serves as a light receiving surface of the solar cell and needs to be light transmissive, and thus is made of a light transmissive material. However, any material may be used as long as it can substantially transmit light having a wavelength having an effective sensitivity to at least a sensitizing dye described later, and it is not always necessary to transmit light in all wavelength regions.

  The light-transmitting material is not particularly limited as long as it is a material that can be generally used for solar cells and can exhibit the effects of the present invention. Examples of such materials include indium tin composite oxide (ITO), fluorine-doped tin oxide (FTO), and zinc oxide (ZnO).

  The conductive support 3 is formed by laminating a transparent conductive layer 2 made of a light transmissive material on a support 1 made of a light transmissive material.

  The film thickness of the transparent conductive layer 2 is preferably about 0.02 to 5 μm, the lower the sheet resistance of the film, the better, and 40Ω / sq or less is preferable.

Moreover, you may provide a metal lead wire in the transparent conductive layer 2 for resistance reduction.
Examples of the metal lead wire material include platinum, gold, silver, copper, aluminum, nickel, and titanium. However, when the metal lead wire is provided to reduce the amount of incident light from the light receiving surface, the thickness of the metal lead wire is preferably about 0.1 to 4 mm.

  These transparent conductive films can be scribed by using a laser.

<Porous semiconductor layer>
The porous semiconductor layer 11 in the present invention is preferably composed of a porous semiconductor layer containing different refractive index materials.

  Here, the refractive index means a refractive index at a measurement wavelength of 550 nm obtained from a change in polarization between incident light and reflected light using a helium (He) -neon (Ne) laser, a xenon (Xe) lamp or the like as a light source. Means.

  The porous semiconductor layer 11 is preferably composed of at least three layers. Of the porous semiconductor layers, the refractive index of the porous semiconductor layer closest to the light incident side and the farthest porous semiconductor layer are higher than the refractive index of the porous semiconductor layer sandwiched therebetween. Is preferred.

  The case where the porous semiconductor layer is composed of three layers will be described with reference to FIG. The dye-sensitized solar cell 8 of the present invention includes a conductive support 3 having a transparent conductive layer 2 on a support 1, a porous semiconductor layer 11a on the transparent conductive layer 2 of the conductive support 3, In the dye-sensitized solar cell 8 including the porous photoelectric conversion layer 31 in which the dye is adsorbed to 11b and 11c, the carrier transport layer 4, and the counter electrode side support 7, the porous semiconductor layer is on the light incident side. The first porous semiconductor layer 11a, the second porous semiconductor layer 11b, and the third porous semiconductor layer 11c are formed in this order. And it is preferable that the refractive index of the 1st porous semiconductor layer 11a and the 3rd porous semiconductor layer 11c is higher than the refractive index of the 2nd porous semiconductor layer 11b.

  With this porous semiconductor layer structure, light is incident from the first porous semiconductor layer 11a and sequentially incident on the second porous semiconductor layer 11b and the third porous semiconductor layer 11c. When light passes from a material having a low refractive index to a material having a high refractive index, the light is bent by a material having a larger refractive index of light, and the light is easily trapped by being sandwiched between the materials having a high refractive index. From the conductive support 3 to the first porous semiconductor layer 11a, light is incident from a low refractive index to a high refractive index, the light is bent, and the light is easily taken into the dye-sensitized solar cell. .

  Further, according to this structure, conventionally, as described in Patent Document 2, a highly refractive material thin film has been provided on a support. However, as in the present invention, a plurality of porous semiconductor layers are provided, By using the porous semiconductor layer 11a as a refractive index material higher than that of the second porous semiconductor layer 11b, the dye can be adsorbed to the porous semiconductor layer, and the conversion efficiency can be improved.

  As the material forming the first porous semiconductor layer 11a, a material having a relatively high refractive index is preferable, and examples thereof include titanium oxide, zinc oxide, and tin oxide. Among these, stability and safety are preferable. From the viewpoint, titanium oxide is particularly preferably used. Examples of titanium oxide include anatase-type titanium oxide, rutile-type titanium oxide, amorphous titanium oxide, various titanium oxides such as metatitanic acid and orthotitanic acid, and titanium hydroxide and hydrous titanium oxide. These constituent materials can be used alone or in combination of two or more. Preferably, rutile type titanium oxide having the highest refractive index is preferable.

The method for forming the first porous semiconductor layer 11a is not particularly limited and a known method can be used. The main methods include the following.
(1) A method of applying a suspension containing semiconductor fine particles on a conductive support and drying and / or firing.
(2) A chemical vapor deposition (CVD) method or a metal organic chemical vapor deposition (MOCVD) method using a predetermined source gas.
(3) Physical vapor deposition (PVD) method using a solid material, for example, vacuum vapor deposition method, sputtering method, ion plating method, ion plating method and the like.
(4) Sol-gel method and the like.

  The method for forming the first porous semiconductor layer 11a is preferably used because (1) is simple and has high performance. The formation method will be specifically described.

  Semiconductor fine particles as a material are added to a dispersant, a solvent, and the like, and dispersed to prepare a suspension, and the suspension is applied onto the conductive support 3. Examples of the coating method include known methods such as a doctor blade method, a squeegee method, a spin coating method, a screen printing method, a spray method, and an ink jet method.

  Then, the 1st porous semiconductor layer 11a is obtained by drying and / or baking a coating film. In either method, a semiconductor layer having a porous property can be obtained, and as described below, a dye can be adsorbed on this layer.

  In drying and firing, it is necessary to appropriately set conditions such as temperature, time, and atmosphere depending on the type of substrate, electrodes, and semiconductor fine particles to be used. Firing can be performed, for example, in an air atmosphere or an inert gas atmosphere within a range of about 50 ° C. to 800 ° C. for about 10 seconds to 12 hours. This drying and baking can be performed once at a single temperature or twice or more by changing the temperature.

In order to improve the photoelectric conversion efficiency of the solar cell, it is necessary to form a photoelectric conversion layer by adsorbing more photosensitizing dyes described later to the porous semiconductor layer. Therefore, preferably has a specific surface area of the film-like porous semiconductor layer large, 10 m ² / g to 200 m approximately ² / g are preferred.

  The material forming the second porous semiconductor layer 11b may be a material not used for the first porous semiconductor layer 11a and a material having a refractive index lower than that of the first porous semiconductor layer 11a. There are no particular restrictions, and various materials can be used. For example, when rutile type titanium oxide is used as the first porous semiconductor layer 11a, anatase type titanium oxide, zinc oxide, tin oxide, strontium titanate, etc. can be preferably used, more preferably. Anatase type titanium oxide is preferable.

  At this time, it is preferable that the refractive index of the 1st porous semiconductor layer 11a and the 3rd porous semiconductor layer 11c is 0.1 or more larger than the refractive index of the 2nd porous semiconductor layer 11b. With a refractive index difference of 0.1 or more, light can be bent sufficiently and conversion efficiency can be improved.

  The material forming the third porous semiconductor layer 11c is not particularly limited as long as it is the same material as the first porous semiconductor layer 11a or a material having a higher refractive index than the second porous semiconductor layer 11b. Various materials can be used. Preferably, zinc telluride, ferric oxide, copper oxide, mercury sulfide, platinum, germanium, arsenic selenide, silicon carbide, titanium oxide, ferric oxide, copper oxide, etc., which are stable and safe From the viewpoint, titanium oxide, ferric oxide, and copper oxide are preferable. More preferably, titanium oxide is used.

  For example, when rutile type titanium oxide is used for the first porous semiconductor layer 11a and anatase type titanium oxide is used for the second porous semiconductor layer 11b, as the third porous semiconductor layer 11c, Rutile titanium oxide can be preferably used. In the case of this combination, since the refractive indexes are 2.71, 2.52, and 2.71, respectively, the first porous semiconductor layer 11a and the third porous semiconductor layer 11b are more than the refractive index of the second porous semiconductor layer 11b. The porous semiconductor layer 11c has a refractive index of 0.1 or more, can bend light, and can improve conversion efficiency.

  In the third porous semiconductor layer 11c, the haze ratio of the third porous semiconductor layer 11c is preferably larger than the haze ratio of the first porous semiconductor layer 11a and the second porous semiconductor layer 11b. Here, the haze ratio means the diffuse transmittance when a light beam having a spectrum in the visible light region and / or near infrared region (for example, the standard light source D65 or the standard light source C) is incident on the measurement sample, It is the value divided by the rate, and is displayed as a value between 0 and 1 or a percentage of 0 to 100%.

  In the case of a porous semiconductor layer composed of a plurality of layers of three or more layers, the porous semiconductor layer closest from the light incident side may be applied to the first porous semiconductor layer, and is the farthest from the light incident side. What is necessary is just to apply a porous semiconductor layer to said 3rd porous semiconductor layer, and what is necessary is just to apply to said 2nd porous semiconductor layer as a porous semiconductor layer formed in the meantime.

  The film thickness of each porous semiconductor layer is not particularly limited, and each porous semiconductor layer may be controlled with a film thickness at which the most current can be obtained by dye adsorption. Specifically, the thickness of the entire porous semiconductor layer is preferably about 0.1 μm to 50 μm, and particularly preferably 1 μm to 35 μm.

<Photosensitizing dye>
Examples of the dye that is adsorbed on the porous semiconductor layer 11 and functions as a photosensitizer include those having absorption in various visible light regions and / or infrared light regions. Furthermore, in order to firmly adsorb the dye to the porous semiconductor layer 11, a carboxyl group, a carboxylic acid anhydride group, an alkoxy group, a hydroxyl group, a hydroxyalkyl group, a sulfonic acid group, an ester group, a mercapto group, Those having an interlocking group such as a phosphonyl group (especially those having a carbon atom of 1 to 3) are preferred. Among these, a carboxylic acid group and a carboxylic anhydride group are more preferable. The interlock group provides an electrical bond that facilitates electron transfer between the excited dye and the conduction band of the porous photoelectric conversion layer.

  Examples of the dyes containing these interlock groups include ruthenium metal complex dyes, azo dyes, quinone dyes, quinone imine dyes, quinacridone dyes, squarylium dyes, cyanine dyes, merocyanine dyes, and triphenylmethane dyes. Xanthene dyes, porphyrin dyes, phthalocyanine dyes, berylene dyes, indigo dyes, naphthalocyanine dyes, and the like.

  Examples of the method for adsorbing the dye on the porous semiconductor layer 11 include a method of immersing the porous semiconductor layer 11 formed on the conductive support 3 in a solution in which the dye is dissolved (dye adsorption solution). . At that time, adsorption may be performed simply at room temperature, or heating by a reflux method may be performed in order to improve the adsorption rate.

  The solvent for dissolving the dye may be any solvent that dissolves the dye. Specifically, alcohols such as ethanol and methanol, ketones such as acetone and diethyl ketone, ethers such as diethyl ether and tetrahydrofuran, acetonitrile , Nitrile compounds such as benzonitrile, halogenated aliphatic hydrocarbons such as chloroform and methyl chloride, aliphatic hydrocarbons such as hexane and pentane, aromatic hydrocarbons such as benzene and toluene, esters such as ethyl acetate and methyl acetate And water. These solvents can be used alone or in admixture of two or more.

The concentration of the dye in the solution can be appropriately adjusted depending on the type of the dye and the solvent used, but is preferably as high as possible in order to improve the adsorption function, for example, 1 to 5 × 10 ⁻⁴ mol. / Liter or more. As an upper limit, although it changes with kinds of the pigment | dye and solvent to be used, a saturated solution or less is preferable.

  In the adsorption method in which the porous semiconductor layer 11 is immersed in the dye solution, the dye solution is filled in a suitable container that can contain the porous semiconductor layer 11, and the entire porous semiconductor layer 11 is immersed in the solution. Alternatively, it is appropriate to immerse only a desired portion of the porous semiconductor layer 11 and hold it for a predetermined time. The conditions at this time can be appropriately adjusted according to the dye used, the type of solvent, the concentration of the solution, and the like. For example, it is appropriate that the temperature of the atmosphere and the solution is room temperature, and the pressure is atmospheric pressure, but these may be appropriately changed. As for immersion time, about 5 minutes-about 100 hours are mentioned, for example. Immersion may be performed once or a plurality of times.

  The dye adsorbed on the porous semiconductor layer 11 functions as a photosensitizer that absorbs light energy to generate excited electrons and sends the electrons to the porous semiconductor layer 11. That is, the porous photoelectric conversion layer 31 can be formed by adsorbing the dye to the porous semiconductor layer 11.

<Carrier transport layer>
The carrier transport layer 4 is formed in contact with the porous photoelectric conversion layer 31 and has a function of transporting electrons to the dye in order to rapidly reduce the oxidized form of the dye.

  The carrier transport layer 4 can be made of a material that can transport electrons, holes, or ions. For example, hole transport materials such as polyvinyl carbazole and triphenylamine, conductive polymers such as polythiophene and polypyrrole, electrolyte solutions (electrolytic solutions), molten salts, solid electrolytes, gel electrolytes and other ionic conductors, copper iodide, thiocyanic acid Examples include inorganic p-type semiconductors such as copper.

The ion conductor is preferably redox, and is not particularly limited as long as it is an electrolyte that can be generally used in batteries, solar cells, and the like. Specifically, LiI, NaI, KI, CsI, and an iodide such as iodine salt of CaI metal iodide, such as _2, and tetraalkylammonium iodide, pyridinium iodide, imidazolium iodide and quaternary ammonium compounds, Mixtures with iodine, bromides such as bromides of metal bromides (such as LiBr, NaBr, KBr, CsBr, CaBr ₂ ) and quaternary ammonium compounds such as tetraalkylammonium bromide, pyridinium bromide, and mixtures of bromine, metal complexes ( Cobalt complexes, ferrocyanate-ferricyanate, ferrocene-ferricinium ions, etc.), sulfur compounds (polysulfide sodium, alkylthiol-alkyl disulfides, etc.), viologen dyes, hydroquinone-quinones, etc. .

  Among these, dimethylpropylimidazolium iodide, LiI, pyridinium iodide, and a mixture of imidazolium iodide and iodine are preferable from the viewpoint of improving open circuit voltage.

  Moreover, you may add nitrogen-containing aromatic compounds, such as t-butyl pyridine (TBP), as an additive conventionally used.

  Solvents constituting the electrolyte solution (electrolytic solution) include carbonate compounds such as ethylene carbonate and propylene carbonate, heterocyclic compounds such as 3-methyl-2-oxazolidinone, ether compounds such as dioxane and diethyl ether, ethylene glycol dialkyl ether, Propylene glycol dialkyl ether, polyethylene glycol dialkyl ether, polypropylene glycol dialkyl ether, ethylene glycol monoalkyl ether, propylene glycol monoalkyl ether, polyethylene glycol monoalkyl ether, polypropylene glycol monoalkyl ether and other ethers, methanol, ethanol and other alcohols , Ethylene glycol, propylene glycol, polyethylene group Examples include polyhydric alcohols such as coal, polypropylene glycol and glycerin, nitrile compounds such as acetonitrile, glutarodinitrile, methoxyacetonitrile, propionitrile, and benzonitrile, aprotic polar substances such as dimethyl sulfoxide and sulfolane, and water. .

  The electrolyte concentration in the electrolytic solution is preferably about 0.1 mol / liter to 5 mol / liter in order to increase the conductivity.

  As the solid electrolyte, a mixture of an electrolyte and an ion conductive polymer compound can be used. Examples of the ion conductive polymer compound include polar polymer compounds such as polyethers, polyesters, polyamines, polysulfides, and polyvinylidene fluoride.

  As a gel electrolyte, what was produced using electrolyte and a gelatinizer can be used. As the gelling agent, a polymer gelling agent is preferably used. Examples thereof include polymer gelling agents such as crosslinked polyacrylic resin derivatives, crosslinked polyacrylonitrile derivatives, polyalkylene oxide derivatives, silicone resins, and polymers having a nitrogen-containing heterocyclic quaternary compound salt structure in the side chain.

  As the molten salt gel electrolyte, a room temperature molten salt to which a gel electrolyte material is added can be used. As room temperature type molten salts, nitrogen-containing heterocyclic quaternary ammonium salt compounds such as pyridinium salts and imidazolium salts are preferably used.

  When forming a carrier transport layer using a solid electrolyte, a gel electrolyte, or a molten salt gel electrolyte, the photoelectric conversion efficiency deteriorates unless the polymer electrolyte is sufficiently injected into the porous semiconductor layer 11. The monomer solution in a state is preferably impregnated into the porous semiconductor layer and then polymerized. Examples of the polymerization method include photopolymerization and thermal polymerization.

<Counter electrode support>
The counter electrode support 7 can constitute a pair of electrodes together with the conductive support 3 on which the porous photoelectric conversion layer 31 is formed, and a substrate 5 in which the conductive layer 6 is formed is widely used. Yes. The conductive layer 6 may be transparent or opaque. The substrate 5 is preferably made of the same material as the support 1. Examples of the conductive layer 6 include metals such as gold, platinum, silver, copper, aluminum, titanium, tantalum, and tungsten; and films made of a transparent conductive material such as ITO, SnO2, and ZnO. If these conductive layers 6 are methods for forming an electrode in general, such as a CVD method, an electroless plating method, an electrodeposition method, a printing method, a thin plate of metal or alloy with an adhesive or a double-sided tape, The film is formed by any known method, and the film thickness is suitably about 0.1 to 5 μm. In order to promote charge transfer with the carrier transport layer 4 on the surface of the conductive layer 6, a catalyst layer such as platinum is preferably formed. In this case, the thickness of the platinum film is about 1 to 1000 nm. The catalyst layer may also serve as the conductive layer 6. When forming a catalyst layer, the material which comprises a catalyst layer will not be specifically limited if it is a material which can generally be used for a solar cell and can exhibit the effect of this invention. As such a material, for example, platinum and carbon are preferable. As the form of carbon, carbon black, graphite, glass carbon, amorphous carbon, hard carbon, soft carbon, carbon whisker, carbon nanotube, fullerene and the like are preferable.

<Spacer>
In order to prevent contact between the porous photoelectric conversion layer 31 and the conductive support 3, a spacer 21 may be used as necessary. As these spacers 21, polymer films such as polyethylene are generally used. The film thickness is suitably about 10 to 50 μm.

<Encapsulant>
The sealing material 22 is preferably provided in order to prevent volatilization of the carrier transport layer 4 and intrusion of water or the like into the battery. The sealing material 22 also has a function of (1) absorbing a fallen object and stress (impact) acting on the support, and (2) absorbing a deflection acting on the support during long-term use.

  The material constituting the sealing material 22 is preferably a silicone resin, an epoxy resin, a polyisobutylene resin, a glass frit, or the like, and these can be used in two or more layers. A hot melt resin can also be used. When a nitrile solvent or a carbonate solvent is used as the solvent for the carrier transport layer, silicone resin, hot melt resin (for example, ionomer resin), polyisobutylene resin, and glass frit are particularly preferable.

  The pattern of the sealing material 22 can be formed by a dispenser when silicone resin, epoxy resin, or glass frit is used. When using a hot melt resin, it can be formed by making a patterned hole in a sheet-like hot melt resin.

With the above configuration, the dye-sensitized solar cell 8 of the present invention can be provided.
<Solar cell module>
FIG. 3 is a cross-sectional view of the solar cell module 121 of the present invention. The solar cell module 121 of the present invention includes a conductive support 119 provided with a transparent conductive layer 112 on a support 110, and a dye for the porous semiconductor layer 114a on the transparent conductive layer 112 of the conductive support 119. The adsorbed porous photoelectric conversion layer 114b, the carrier transport layer 117, the counter electrode-side support 120 in which the conductive layer 116 and the catalyst layer 115 are deposited in the above order on the support 111, and the catalyst on the support 110. It comprises an inter-cell insulating layer 113 formed between the layers 115 and a conductive connection layer 118 formed between the adjacent inter-cell insulating layers 113.

  A solar cell module 121 (hereinafter also referred to as “module”) can be provided by connecting a plurality of the dye-sensitized solar cells of the present invention. When the module 121 is manufactured, the porous semiconductor layer 114a is formed on the conductive substrate 119 that has been scribed in advance, the dye is adsorbed, the porous photoelectric conversion layer 114b is formed, and the counter electrode side support 120 is formed. It is preferable to connect the adjacent cells using the conductive connection layer 118 for connecting the dye-sensitized solar cells.

  When producing a dye-sensitized solar cell module as shown in FIG. 3, a catalyst layer and a conductive film may be formed on a desired porous semiconductor layer 114a. Moreover, when using metals other than Pt as a counter electrode, it is preferable to form the catalyst layer 115 on the surface, and it is preferable to form a thin layer with Pt or carbon. There is no limitation on the method of forming the counter electrode, and a method of forming an electrode in general, such as a CVD method, an electroless plating method, an electrodeposition method, a printing method, or a metal or alloy thin plate attached with an adhesive or double-sided tape. Any known method may be used as long as it exists. The counter electrode may be composed of a catalyst layer and a conductive layer.

<Conductive connection layer>
A conductive connection layer 118 is provided between the dye-sensitized solar cells in the dye-sensitized solar cell module 121 in the thickness direction, and the transparent conductive layer 112 and the adjacent counter electrode support 120 are electrically connected. It is preferable to do so. The conductive connection layer 118 is made of a conductive material. Preferably, any of gold, silver, platinum, chromium, nickel, titanium, or an alloy of two or more thereof, or a transparent conductive material can be used, and the same as the transparent conductive film 112 or the counter electrode side support 120 It may be made of any material. Moreover, the thickness should just have the thickness between the electroconductive support body 119 and the counter electrode side support body 120. FIG.

<Insulation layer between cells>
In order to electrically insulate the conductive connection layer 118 and the porous photoelectric conversion layer 114b, it is preferable to provide an inter-cell insulating layer 113 on both sides of the conductive connection layer 118. The material of the inter-cell insulating layer 113 is not particularly limited, but glass frit, ultraviolet curable resin, thermosetting resin, and the like are preferable. When glass frit is used, it is preferable to perform various printing methods such as screen printing. The resin is preferably applied by a syringe or a dispenser.

The sealing material (not shown) may be the same as that of the dye-sensitized solar cell.
With the above configuration, the dye-sensitized solar cell module 121 in which the dye-sensitized solar cells of the present invention are connected in series can be provided.

  Examples The present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

<Example 1>
An explanation will be given based on FIG.

(Preparation of porous semiconductor layer)
Titanium oxide particles (manufactured by Teika Co., Ltd., product name: AMT-600, particle size of about 30 nm) were baked at 800 ° C. for 2 hours to produce rutile titanium oxide particles (titanium oxide A).

  In the rutile-type titanium oxide particle suspension, titanium oxide A was added to terpineol, 100 g of zirconia beads (diameter 2 mm) was added to 40 ml of the solution, and the dispersion time on the paint shaker was 2 hours and 24 hours. . The solution having passed through these dispersions is filtered to remove zirconia beads, and the filtrate is concentrated with an evaporator until titanium oxide reaches a concentration of 15 wt%, and then twice the ethanol of this solution is added and centrifuged at 5000 rpm. Separation was performed. After the titanium oxide particles produced in this step were washed with ethanol, a solution in which ethylcellulose and terpineol were dissolved in absolute ethanol was added and stirred to disperse the titanium oxide particles in the solution. The ethanol was evaporated at 50 ° C. under a vacuum of 40 mbar to prepare a suspension. The final composition was adjusted so that the titanium oxide concentration was 10 wt%, ethylcellulose 10 wt%, and terpineol 64 wt%, and suspension A (dispersion time: 24 hours), suspension B (dispersion time: 2 hours) ) Was produced.

Tin-coated glass plate oxide (electroconductive support 3) (Nippon Sheet Glass Co., Ltd., trade name: SnO ₂ film-coated glass, SnO ₂ film thickness: 500 nm) to the suspension A was applied by screen printing, porous After the porous semiconductor layer 11a is formed and pre-dried at 80 ° C. for 20 minutes, it is fired at 500 ° C. for 1 hour using an electric furnace (Denken Co., Ltd., trade name: KDF-P70), and the first porous layer The semiconductor layer 11a was produced. The film thickness of the first porous semiconductor layer 11a at this time was 5 μm. The refractive index was 2.71 as measured by an ellipsometer (Moritex, ME-ELP-SD).

  Subsequently, the porous semiconductor layer 11b has a width of 5 mm and a length of 50 mm by screen printing using a titanium oxide paste (manufactured by Solaronix, trade name: Ti-Nanoxide DS / P). The layer 11b was formed, preliminarily dried at 80 ° C. for 20 minutes, and then baked at 500 ° C. for 1 hour using an electric furnace to produce the second porous semiconductor layer 11b. At this time, the film thickness of the second porous semiconductor layer 11b was 5 μm. The refractive index was 2.52.

  Subsequently, the suspension A was applied by screen printing to form a porous semiconductor layer 11c, preliminarily dried at 80 ° C. for 20 minutes, and then baked at 500 ° C. for 1 hour using an electric furnace. A porous semiconductor layer 11c was prepared. The film thickness of the third porous semiconductor layer 11c at this time was 5 μm. The refractive index was 2.71.

(Preparation of porous photoelectric conversion layer)
Next, a sensitizing dye N719 (manufactured by Solaronix, trade name: Ru535bisTBA, ruthenium dye) represented by the following formula (1) is dissolved in ethanol so as to have a concentration of 3 × 10 ⁻⁴ mol / liter, and the dye A solution was obtained. Subsequently, the porous semiconductor layers 11a, 11b, and 11c prepared on the conductive support 3 were immersed in the dye solution for 12 hours, and the sensitizing dye was adsorbed on the porous semiconductor layers 11a, 11b, and 11c. Thereafter, the porous semiconductor layers 11a, 11b, and 11c were washed with ethanol and dried to obtain a porous photoelectric conversion layer 31.

Formula (1)
(In the chemical formula, TBA is tetrabutylammonium.)
(Production of counter electrode support)
Subsequently, a tin oxide coated glass plates (counter side support 7: are formed from the substrate 5 and the conductive film 6) (manufactured by Nippon Sheet Glass Co., Ltd., trade name: SnO ₂ film-coated glass, SnO ₂ film thickness: 500 nm) In addition, platinum was formed by sputtering, and a counter electrode could be produced. Thereafter, an electrolyte inlet (not shown) was opened in the counter electrode support 7.

(Preparation of sealing material)
The counter electrode side support body 7 and the conductive support body 3 on which the porous photoelectric conversion layer 31 is formed are overlapped with each other through a 50 μm-thick high Milan (manufactured by DuPont), and an electrolyte is injected into the gap. Was sealed with resin to prepare a sealing material. The electrolytes were acetonitrile (Aldrich), LiI (0.1M, Aldrich), I ₂ (0.05M, Aldrich), t-butylpyridine (0.5M, Aldrich), dimethylpropylimidazolium iodide. What dissolved (0.6M, Shikoku Chemicals) was used.

(Measuring method)
The obtained solar cell 8 is irradiated with light having an intensity of 1 kW / m ² (AM1.5 solar simulator), and short circuit current (Jsc), open circuit voltage (Voc), fill factor (FF), and photoelectric conversion efficiency ( Eff (%), also referred to as “conversion efficiency”). The cell characteristics are summarized in Table 1.

<Example 2>
In Example 1, a dye-sensitized solar cell was produced in the same manner as in Example 1 except that strontium titanate was used for the second porous semiconductor layer 1b.

  The porous layer of strontium titanate was formed in the same manner as the method for preparing the suspension A in Example 1 using particles of strontium titanate (manufactured by Wako Pure Chemical Industries). The refractive index of this layer was 2.37. The cell characteristics are summarized in Table 1.

<Example 3>
In Example 1, a dye-sensitized solar cell was produced in the same manner as in Example 1 except that the suspension B was used for the third porous semiconductor layer 1c. The refractive index was 2.71. The first porous semiconductor layer 1a using the suspension A (dispersion time: 24 hours) has a haze ratio of 3%, and the third porosity using the suspension B (dispersion time: 2 hours). The haze ratio of the quality semiconductor layer 1c was 75%. The cell characteristics are summarized in Table 1.

<Example 4>
For the suspension of ferric oxide particles (refractive index: 3.01), fine iron oxide (manufactured by JFE Chemical) is added to terpineol, and 100 g of zirconia beads (diameter 2 mm) are added to 40 ml of the solution. The dispersion time on the shaker was 8 hours. The solution having passed through these dispersions is filtered to remove zirconia beads, and the filtrate is concentrated with an evaporator until ferric oxide has a concentration of 15 wt%, and then ethanol twice as much as this solution is added to 5000 rpm. Centrifugation was performed. After washing the ferric oxide particles produced in this step with ethanol, a solution in which ethylcellulose and terpineol were dissolved in absolute ethanol was added and stirred to disperse the ferric oxide particles in the solution. The ethanol was evaporated at 50 ° C. under a vacuum of 40 mbar to prepare a suspension. As a final composition, the concentration was adjusted so that the ferric oxide concentration was 10 wt%, ethyl cellulose was 10 wt%, and terpineol was 64 wt% to prepare Suspension C.

  In Example 1, a dye-sensitized solar cell was produced in the same manner as in Example 1 except that the suspension C was used for the third porous semiconductor layer 1c. The cell characteristics are summarized in Table 1.

<Example 5>
In Example 4, a dye-sensitized solar cell was obtained in the same manner as in Example 4 except that the ferric oxide was changed to copper oxide (cuprous oxide) (manufactured by Furukawa Chemicals) (refractive index: 2.71). Was made. The cell characteristics are summarized in Table 1.

<Example 6>
This will be described with reference to FIG.

(Formation of inter-cell insulation layer)
Tin-coated glass plate oxide (Nippon Sheet Glass Co., Ltd., trade name: SnO ₂ film-coated glass, SnO ₂ film thickness: 500 nm, a glass substrate shape: Vertical 7 cm, horizontal 7 cm, thickness 1.1 mm) and, using a laser scribing device Then, the tin oxide was removed according to the pattern of the porous semiconductor layer 114a to be formed later.

  Subsequently, using a glass frit (product name: AP5346, manufactured by Asahi Glass Co., Ltd.), it was applied to the position of the inter-cell insulating layer 113 in FIG. 3 and pre-dried at 80 ° C. for 20 minutes. The product was fired at 550 ° C. for 1 hour using a product name, KDF-P70, to form an inter-cell insulating layer 113.

(Preparation of porous semiconductor layer)
Next, as shown in FIG. 3, on the transparent conductive layer 112, the suspension A is used as the first porous semiconductor layer, and the titanium oxide paste (trade name, manufactured by Solaronix Co., Ltd.) is used as the second porous semiconductor layer. : Ti-Nanoxide DS / P) as the third porous semiconductor layer, the suspension A was used, and the porous semiconductor layer 114a had a width of 5 mm and a length of 50 mm by screen printing. The semiconductor layer 114a was formed, pre-dried at 80 ° C. for 20 minutes, and then fired at 500 ° C. for 1 hour using an electric furnace (manufactured by Denken Co., Ltd., trade name: KDF-P70). A semiconductor layer 114a was obtained. At this time, two inter-cell insulating layers 113 are formed at a pitch of 1 mm between the porous semiconductor layers 114a. Nine porous semiconductor layers 114a were formed.

(Formation of conductive connection layer)
A commercially available conductive paste (trade name “Dotite”, manufactured by Fujikura Kasei Co., Ltd.) was poured into the two gaps of the inter-cell insulating layer 113 and dried to form the conductive connection layer 118.

(Formation of porous photoelectric conversion layer)
Next, a sensitizing dye N719 represented by the above formula (1) (manufactured by Solaronix, trade name: Ru535bisTBA, ruthenium dye) is dissolved in ethanol so as to have a concentration of 3 × 10 ⁻⁴ mol / liter, and the dye A solution was obtained. Subsequently, the porous semiconductor layer 114a previously prepared on the support was immersed in a dye solution for 12 hours to adsorb the sensitizing dye to the porous semiconductor layer titanium oxide film. Thereafter, the porous semiconductor layer was washed with ethanol and dried to obtain a porous photoelectric conversion layer 114b.

(Production of counter electrode)
Subsequently, a counter electrode is produced. Similarly to the previous step, the tin oxide-attached glass plate was removed with a laser scribing device so as to match the pattern of the porous semiconductor layer prepared earlier. Platinum was formed by patterning by sputtering so that platinum was not formed where the tin oxide was removed. Thereby, the counter electrode was produced. Thereafter, an electrolyte inlet (not shown) was opened.

(Production of solar cell module)
The porous semiconductor layer 114a and the counter electrode produced in the above-described process are coated with UV curable resin (manufactured by ThreeBond: product name 31x-088) on the inter-cell insulating layer 113, and bonded together as shown in FIG. , Quickly lit UV light. Thereafter, the electrolytic solution was injected by a capillary effect to form a carrier transport layer 117, and the periphery was coated with the above-described UV curable resin, irradiated with UV light, and sealed to prepare a solar cell module 121.

(Measuring method)
The obtained solar cell module 121 is irradiated with light having an intensity of 1 kW / m ² (AM1.5 solar simulator), and short circuit current (Jsc), open circuit voltage (Voc), fill factor (FF), and photoelectric conversion efficiency (Eff (%), also referred to as “conversion efficiency”) was measured. The cell characteristics are summarized in Table 1.

<Comparative Example 1>
In Example 1, except that the first to third porous semiconductor layers were all prepared using titanium oxide paste (manufactured by Solaronix, trade name: Ti-Nanoxide DS / P), as in Example 1, A dye-sensitized solar cell was produced. The cell characteristics are summarized in Table 1.

<Comparative example 2>
In Example 1, a dye-sensitized solar cell was prepared in the same manner as in Example 1 except that the first porous semiconductor layer was prepared using a titanium oxide paste (manufactured by Solaronix, trade name: Ti-Nanoxide DS / P). A battery was produced. The cell characteristics are summarized in Table 1.

<Comparative Example 3>
In Example 1, a dye-sensitized solar layer was prepared in the same manner as in Example 1 except that the third porous semiconductor layer was prepared using a titanium oxide paste (manufactured by Solaronix, trade name: Ti-Nanoxide DS / P). A battery was produced. The cell characteristics are summarized in Table 1.

<Comparative example 4>
In Example 4, except that the first to third porous semiconductor layers were all produced using a titanium oxide paste (manufactured by Solaronix, trade name: Ti-Nanoxide DS / P), the same as in Example 4, A dye-sensitized solar cell was produced. The cell characteristics are summarized in Table 1.

  From the above results, it can be seen that the conversion efficiency is improved when the refractive indexes of the first and third porous semiconductor layers are higher than the refractive index of the second porous semiconductor layer. It was also confirmed that the present invention can provide a dye-sensitized solar cell module with improved characteristics.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a schematic sectional drawing of the dye-sensitized solar cell of this invention. It is a schematic sectional drawing of the dye-sensitized solar cell of this invention. It is a schematic sectional drawing of the solar cell module of this invention.

Explanation of symbols

  1,110,111 Support, 2,112 Transparent conductive layer, 3,119 Conductive support, 4,117 Carrier transport layer, 5 Substrate, 6,116 Conductive layer, 7,120 Counter electrode support, 8 Dye enhancement Sensitive solar cell, 11, 114a porous semiconductor layer, 21 spacer, 22 sealing material, 31, 114b porous photoelectric conversion layer, 113 inter-cell insulation layer, 115 catalyst layer, 118 conductive connection layer, 121 solar cell module .

Claims (7)

  A conductive support provided with a transparent conductive layer on a support, a porous photoelectric conversion layer in which a dye is adsorbed on a porous semiconductor layer on the transparent conductive layer of the conductive support, a carrier transport layer, and a counter electrode In a dye-sensitized solar cell including a side support, the porous semiconductor layer is composed of at least three layers, and is formed farthest from the porous semiconductor layer formed closest to the incident direction of light. A dye-sensitized solar cell, wherein the refractive index of the porous semiconductor layer formed is higher than the refractive index of the porous semiconductor layer formed therebetween.   The porous semiconductor layer is composed of three layers, and is formed in the order of the first porous semiconductor layer, the second porous semiconductor layer, and the third porous semiconductor layer in order from the incident direction of light, and the second The dye-sensitized solar cell according to claim 1, wherein the refractive index of the first and third porous semiconductor layers is larger than the refractive index of the porous semiconductor layer.   The refractive index of said 1st porous semiconductor layer and the 3rd porous semiconductor layer is 0.1 or more larger than the refractive index of a 2nd porous semiconductor layer, The Claim 1 or 2 characterized by the above-mentioned. The dye-sensitized solar cell described.   The dye-sensitized solar cell according to any one of claims 1 to 3, wherein the first porous semiconductor layer is a rutile type titanium oxide.   The dye-sensitized solar cell according to any one of claims 1 to 4, wherein the second porous semiconductor layer is anatase-type titanium oxide or strontium titanate.   The dye-sensitized solar cell according to any one of claims 1 to 5, wherein the third porous semiconductor layer is a rutile type titanium oxide.   A dye-sensitized solar cell module using the dye-sensitized solar cell according to claim 1.

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