JP5521419B2 - Electrolyte forming coating solution and dye-sensitized solar cell using the same - Google Patents

Description

  The present invention relates to a coating solution for forming an electrolyte in a dye-sensitized solar cell. Moreover, it is related with the dye-sensitized solar cell and solar cell module which are produced using the coating liquid.

  In recent years, global warming caused by carbon dioxide has become a global problem. In recent years, active research and development of solar cells using solar energy has been promoted as an environmentally friendly and clean energy source. . Among them, a dye-sensitized solar cell has attracted attention as a solar cell with higher photoelectric conversion efficiency and lower cost.

  A dye-sensitized solar cell includes, for example, a transparent substrate, a transparent electrode formed on the transparent substrate, an oxide semiconductor layer carrying a dye, an electrolyte layer having an electrolyte, and a counter electrode from the light incident side. A cell is formed by sequentially stacking the substrates on which the layers are formed. In particular, Gretcher cell is characterized by using a porous oxide semiconductor layer obtained by firing titanium oxide, which is a nanoparticulate, and increasing the adsorption amount of sensitizing dye by making the oxide semiconductor layer porous. The light absorption ability is improved.

  For example, the dye-sensitized solar cell may be manufactured by first forming a porous semiconductor layer made of titanium oxide particles on a transparent electrode formed on the surface of a transparent substrate, and applying the dye to the porous semiconductor layer. Support. Next, after coating the counter electrode with a catalyst such as a platinum film and stacking the semiconductor layer and the platinum film so as to face each other, an electrolyte is injected between them by a technique such as a vacuum injection method to form an electrolyte layer, Seal the inlet with a sealing material such as epoxy resin. In this way, a dye-sensitized solar cell is produced.

  However, conventionally, since a liquid electrolyte has been used for the electrolyte layer, there has been a problem that electrolyte leakage from the inlet and air intrusion occur, resulting in a decrease in photoelectric conversion efficiency and a deterioration in durability. There is also a problem that the injection time becomes longer as the cell size increases. On the other hand, a dye-sensitized solar cell in which an electrolyte layer is quasi-solidified to prevent liquid leakage has been proposed.

  For example, (Patent Document 1) discloses a gel electrolyte composition including an ionic liquid and conductive particles such as carbon nanotubes or oxide semiconductor particles such as titanium oxide. However, the gel electrolyte to which nanoparticles such as carbon nanotubes are added has a low electrolyte solution retention, and the electrolyte solution oozes out, so there is still a problem in durability over a long period of time.

International Publication No. 2005/006482 Pamphlet

  Therefore, in view of the above-described conventional situation, an object of the present invention is to provide a coating solution for stably forming a quasi-solid shape over a long period of time and forming an electrolyte having a high electrolytic solution retainability. Moreover, it aims at providing the dye-sensitized solar cell excellent in durability produced using such a coating liquid, and a solar cell module.

  The present inventor confined the electrolyte in the mesopores by containing at least one porous nanoparticle selected from metal oxide particles and conductive particles having mesopores as a component in the electrolyte. As a result, the present invention was completed. That is, the gist of the present invention is as follows.

(1) A coating liquid for forming an electrolyte of a dye-sensitized solar cell, comprising an electrolytic solution comprising a redox couple and an ionic liquid, and metal oxide particles and conductive particles having mesopores An electrolyte forming coating solution containing at least one selected from the above.
(2) The electrolyte forming coating solution according to (1), wherein one or more selected from metal oxide particles and conductive particles having mesopores is mesoporous silica.
(3) The electrolyte according to (1) or (2) above, wherein one or more selected from metal oxide particles and conductive particles having mesopores is contained in an amount of 5 to 20 parts by weight with respect to 100 parts by weight of the electrolytic solution. Forming coating liquid.
(4) an electrode base material, a porous semiconductor layer formed on the electrode base material with a sensitizing dye supported on the pore surface, a counter electrode base material disposed opposite the porous semiconductor layer, and an electrode base The dye-sensitized solar cell comprised from the electrolyte layer formed from the coating liquid in any one of said (1)-(3) arrange | positioned between a material and a counter electrode base material.
(5) A dye-sensitized solar cell module formed by connecting a plurality of the dye-sensitized solar cells according to (4) in series or in parallel.

  According to the present invention, the coating liquid for forming the electrolyte is formed from the coating liquid by including metal oxide particles such as mesoporous silica having pores having a diameter of about 2 to 50 nm or conductive particles. Therefore, it is possible to improve the retention of the electrolytic solution in the electrolyte to be maintained, and to maintain the quasi-solid shape stably over a long period of time. Further, by using such an electrolyte, a dye-sensitized solar cell and a dye-sensitized solar cell module excellent in durability can be obtained.

It is sectional drawing which shows one Embodiment of the dye-sensitized solar cell of this invention.

Next, the present invention will be described in detail based on embodiments.
FIG. 1 is a cross-sectional view showing an embodiment of the dye-sensitized solar cell of the present invention. This dye-sensitized solar cell 1 is opposed to an electrode substrate 10, a porous semiconductor layer 20 formed on the electrode substrate 10 with a sensitizing dye supported on the pore surface, and the porous semiconductor layer 20. And the counter electrode base material 40 disposed in a row, and the electrolyte layer 30 formed between the electrode base material 10 and the counter electrode base material 40.

  Hereinafter, each element which comprises the dye-sensitized solar cell 1 is demonstrated.

(1) Electrode base material and counter electrode base material The electrode base material 10 and the counter electrode base material 40 can be obtained by forming an electrode layer on the surface of a substrate such as glass or plastic, respectively. The substrate may be transparent or opaque, but when it is located on the light receiving surface side, it is preferably a transparent substrate having excellent light transmittance. Furthermore, it is preferable that it is excellent in heat resistance, weather resistance, and gas barrier properties against water vapor and the like. Specifically, transparent flexible materials such as quartz glass, Pyrex (registered trademark), and synthetic quartz glass that are not flexible, ethylene-tetrafluoroethylene copolymer film, biaxially stretched polyethylene terephthalate film, polyethersulfone Examples thereof include plastic films such as a film, a polyether ether ketone film, a polyether imide film, a polyimide film, and a polyester naphthalate. In particular, an electrode base material and a counter electrode base material made of a flexible film in which a plastic film is used as a substrate and an electrode layer is formed thereon are preferably used. Thereby, a solar cell can be used for various uses, and the weight of the solar cell can be reduced and the manufacturing cost can be reduced. The plastic film may be used alone as a substrate, or may be used in a state where two or more different plastic films are laminated.

  The thickness of each of the electrode base material and the counter electrode base material is preferably in the range of 15 to 500 μm.

The material of the electrode layer formed on the substrate is not particularly limited as long as it has excellent conductivity, but the electrode layer located on the light receiving surface side has excellent light transmission. Preferably there is. For example, as a material having excellent light _{permeability,} may be mentioned SnO 2, ITO, IZO, ZnO or the like. Among these, fluorine-doped SnO ₂ (FTO) and ITO are particularly preferably used because they are excellent in both conductivity and permeability.

Moreover, it is preferable to select materials for the electrode layers on the electrode base material side and the counter electrode base material side in consideration of respective work functions. For example, a high work function materials include Au, Ag, Co, Ni, Pt, C, ITO, and SnO _{2, SnO} 2, ZnO or the like fluorine-doped. On the other hand, examples of the material having a low work function include Li, In, Al, Ca, Mg, Sm, Tb, Yb, and Zr.

  Each electrode layer may be formed of a single layer or may be formed by stacking materials having different work functions.

  The film thickness of the electrode layer is in the range of 0.1 nm to 500 nm, preferably in the range of 1 nm to 300 nm.

  A method for forming such an electrode layer is not particularly limited, and examples thereof include a vapor deposition method, a sputtering method, and a CVD method. Among these, the sputtering method is preferably used.

  Further, as the counter electrode base material 40, a metal plate or a metal foil made of aluminum or the like can be used in addition to the form in which the electrode layer is formed on the substrate as described above.

  The power generation efficiency of the dye-sensitized solar cell can be further improved by further forming a catalyst layer on the side of the counter electrode substrate facing the electrolyte layer. Examples of the catalyst layer include Pt-deposited layers, conductive polymers such as polyaniline, polythiophene, polypyrrole, or poly (3,4-ethylenedioxythiophene) doped with polystyrene sulfonic acid (PEDOT / PSS). However, the layer is not limited to this. When forming a catalyst layer containing a conductive polymer, the conductive polymer is dispersed and dissolved in a solvent, applied on the counter electrode substrate using various coating methods, and then dried appropriately to remove the solvent. Thus, a catalyst layer can be formed.

(2) Porous semiconductor layer Next, the porous semiconductor layer 20 will be described. The porous semiconductor layer has metal oxide semiconductor particles, on which a sensitizing dye is supported, and has a function of conducting charges generated from the sensitizing dye by light irradiation.

  The metal oxide semiconductor particles are preferably porous having communication holes because the sensitizing dye is supported on the surface of the pores. By setting it as such a porous, the surface area of a porous semiconductor layer becomes large, and sufficient quantity of a sensitizing dye can be carry | supported. Moreover, a contact area with the electrolyte layer mentioned later becomes large, and energy conversion efficiency can be improved.

  The film thickness of the porous semiconductor layer is preferably in the range of 1 μm to 100 μm, and more preferably in the range of 5 μm to 30 μm. This is because the film resistance of the porous semiconductor layer can be reduced within the above range, and light absorption by the porous semiconductor layer is sufficiently performed.

The metal oxide semiconductor particles forming the porous semiconductor layer are not particularly limited as long as the charge generated from the sensitizing dye can be conducted to the electrode layer of the electrode substrate 10. _{Specifically, TiO 2, ZnO, SnO 2} , ITO, ZrO 2, SiO 2, MgO, Al 2 O 3, CeO 2, Bi 2 O 3, Mn 3 O 4, Y 2 O 3, WO 3, Ta ₂ O ₅ , Nb ₂ O ₅ , La ₂ O _{3 and the} like can be mentioned. Any one kind of these metal oxide semiconductor particles may be used, or two or more kinds may be mixed and used. Among these, TiO ₂ can be preferably used. Further, a core-shell structure in which one of these is used as a core particle and the core particle is covered with another metal oxide semiconductor particle to form a shell may be employed.

  The content of the metal oxide semiconductor particles in the porous semiconductor layer is preferably in the range of 40 to 99.9% by weight, and more preferably in the range of 85 to 99.5% by weight.

  The particle size of the metal oxide semiconductor particles is preferably in the range of 1 nm to 10 μm, particularly in the range of 10 nm to 500 nm. When the particle diameter is smaller than the above range, it is difficult to produce such particles, and it is not preferable because each particle may aggregate to form secondary particles. On the other hand, when the particle diameter is larger than the above range, the porous semiconductor layer becomes thicker and the resistance becomes higher, which is not preferable.

  A mixture of the same or different metal oxide semiconductor particles having different particle diameters may be used. Thereby, the light scattering effect can be enhanced and more light can be confined in the porous semiconductor layer, so that light absorption by the sensitizing dye can be efficiently performed. For example, the case where 10-50 nm metal oxide semiconductor particle and 50-200 nm metal oxide semiconductor particle are mixed and used can be mentioned.

  The sensitizing dye supported on the metal oxide semiconductor particles is not particularly limited as long as it can absorb light and generate an electromotive force. Specifically, an organic dye or a metal complex dye can be used. Examples of organic dyes include acridine, azo, indigo, quinone, coumarin, merocyanine, phenylxanthene, indoline, and squalium dyes. In particular, a coumarin system is preferably used.

  As the metal complex dye, a ruthenium dye, particularly a ruthenium bipyridine dye and a ruthenium terpyridine dye are preferably used. By supporting such a sensitizing dye on the pore surfaces of the metal oxide semiconductor particles, it is possible to efficiently take in the visible light range and cause photoelectric conversion.

  The method for forming the porous semiconductor layer is not particularly limited, but it is preferably formed by a coating method. That is, using a known disperser such as a homogenizer, a ball mill, a sand mill, a roll mill, or a planetary mixer, a coating liquid in which metal oxide semiconductor particles are dispersed in a solvent is prepared. It is applied onto the electrode layer, dried, and further baked as necessary. Thereafter, the porous semiconductor layer carrying the sensitizing dye can be formed by adsorbing the sensitizing dye on the surface of the metal oxide semiconductor particles.

  The solvent used in the metal oxide semiconductor particle coating solution is not particularly limited. Specifically, chlorine solvents such as chloroform, methylene chloride, dichloroethane, ether solvents such as tetrahydrofuran, aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as acetone and methyl ethyl ketone, ethyl acetate, butyl acetate And ester solvents such as ethyl cellosolve acetate, alcohol solvents such as isopropyl alcohol, ethanol, methanol and butyl alcohol, N-methyl-2-pyrrolidone, and pure water.

  In addition, various additives may be used as necessary in order to improve the coating suitability of the coating liquid used for forming the porous semiconductor layer. As the additive, a surfactant, a viscosity adjuster, a dispersion aid, a pH adjuster and the like can be used. Examples of the pH adjuster include nitric acid, hydrochloric acid, acetic acid, ammonia and the like.

  The method for applying the coating liquid containing metal oxide semiconductor particles is not particularly limited as long as it is a known application method, and specifically, die coating, gravure coating, gravure reverse coating, roll coating, reverse roll coating. , Bar coating, blade coating, knife coating, air knife coating, slot die coating, slide die coating, dip coating, micro bar coating, micro bar reverse coating, screen printing, and the like. Using such a coating method, the porous semiconductor layer is formed so as to have a desired film thickness by repeating coating and drying once or a plurality of times.

  After coating and drying, baking is performed as necessary. Thereby, the porous semiconductor layer can be homogenized and densified, and the binding property between the metal oxide semiconductor particles is increased, so that the charge conductivity can be improved. Moreover, the adhesiveness of an electrode base material and a porous semiconductor layer can also be improved. The firing temperature and time vary depending on the film thickness of the porous semiconductor layer and are not limited, but are generally about 300 to 700 ° C. for about 5 to 120 minutes. Moreover, when an electrode base material is comprised from a flexible film, it is preferable to perform drying and baking below the heat-resistant temperature of a film.

  Examples of the method of supporting the sensitizing dye include, for example, a method in which the dried and fired metal oxide semiconductor particles are immersed in a sensitizing dye solution and then drying, or a sensitizing dye solution on the metal oxide semiconductor particles. The method of drying after apply | coating to it, making it infiltrate, etc. can be mentioned. The solvent used in the sensitizing dye solution is appropriately selected from an aqueous solvent and an organic solvent according to the type of the dye sensitizer used.

(3) Electrolyte Layer Next, the electrolyte layer 30 will be described. The electrolyte layer 30 is formed between the electrode substrate 10 and the counter electrode substrate 40, and is selected from an electrolytic solution composed of a redox pair and an ionic liquid, and metal oxide particles and conductive particles having mesopores. It is produced from a coating solution containing at least the above.

  The redox couple can be appropriately selected from those generally used in the electrolyte layer. Specifically, a redox couple of iodine or a redox couple of bromine is preferably used. Examples of the redox pair of iodine include combinations of iodine and iodides such as lithium iodide, sodium iodide, potassium iodide, calcium iodide, and TPAI (tetrapropylammonium iodide). Examples of the redox pair of bromine include combinations of bromine and bromides such as lithium bromide, sodium bromide, potassium bromide, and calcium bromide.

  The concentration of the redox couple in the electrolyte layer 30 varies depending on the type of the redox couple and is not particularly limited. In general, when an iodine or bromine redox couple is used, iodine or bromine is 0% in the electrolyte layer. 0.01 to 0.5 mol / l, and iodide or bromide is preferably 0.1 to 5 mol / l.

  The ionic liquid (room temperature molten salt) lowers the viscosity of the electrolyte, improves the conductivity of ions, and improves the photoelectric conversion efficiency. Ionic liquids have a very low vapor pressure, and hardly evaporate at room temperature. There is no fear of volatilization or ignition like ordinary organic solvents, so it is possible to prevent deterioration of cell characteristics due to volatilization. .

  Examples of the ionic liquid include 1-methyl-3-methylimidazolium, 1-ethyl-3-methylimidazolium, 1-butyl-3-methylimidazolium, and 1-hexyl-3-methylimidazole. 1-octyl-3-methylimidazolium, 1-octadecyl-3-methylimidazolium, 1-methyl-2,3-dimethylimidazolium, 1-butyl-2,3-dimethylimidazolium, 1-hexyl- Imidazolium compounds such as 2,3-dimethylimidazolium, 1-octyl-2,3-dimethylimidazolium, 1-octadecyl-2,3-dimethylimidazolium, 1-methyl-pyridium, 1-butyl-pyridium, 1 -Pyridines such as hexyl-pyridium, alicyclic amines, aliphatic amines, Anion is, may be mentioned iodine ion, a bromine ion, a chlorine ion, tetrafluoroborate, hexafluoro borate, trifluoromethanesulfonate, fluorine-based, such as trifluoroacetate, cyanate system, such as those thiocyanates system. Any one of these substances may be used alone, or a plurality of these substances may be mixed and used.

  In particular, it is preferable to use an iodide ionic liquid having iodine as an anion. Specifically, for example, 1,2-dimethyl-3-n-propylimidazolium iodide, 1-methyl-3-n-propylimidazolium iodide, 1-propyl-3-methylimidazolium iodide, 1 -Butyl-2,3-dimethylimidazolium iodide, 1-hexyl-3-methylimidazolium iodide, etc. can be mentioned. These iodide ionic liquids are a source of iodine ions and can also function as the above-described redox couple.

  The concentration of the ionic liquid in the electrolyte layer varies depending on the type of the ionic liquid, but is preferably 1 to 95% by weight, particularly 30 to 95% by weight in the electrolyte layer. An ionic liquid that also functions as a redox pair, such as an iodide ionic liquid, is preferably contained as a redox pair, and preferably has the concentration described for the redox pair, that is, the electrolyte layer. It is preferable to contain 0.1-5 mol / l in. In that case, as the above-described redox couple, iodides other than the iodide-based ionic liquid may or may not be contained. As a result, the total concentration of iodides functioning as the redox couple is 0.1 to 10. It may be 5 mol / l.

  The present invention is characterized in that the electrolyte layer 30 contains metal oxide particles or conductive particles having mesopores. Here, the mesopores are defined in IUPAC (International Pure and Applied Chemistry Association) and mean pores having a pore diameter of 2 nm or more and 50 nm or less. By using particles that have larger mesopores than conventional pores (0.5 to 2 nm micropores) commonly found in zeolites, etc., the electrolyte solution is retained in the pores, and the quasi-solid state of the electrolyte layer The shape can be maintained for a long time. In addition, any one of these metal oxide particles or conductive particles may be contained, or both may be contained in a mixed state.

  The mesopores may be, for example, a state in which pores are regularly arranged in a honeycomb shape on the surface of the particles, or irregularly arranged. The mesopore diameter may be 2 to 50 nm, preferably 2 to 10 nm. In addition, the hole diameter in this case means the diameter when the cross-sectional shape of the hole is a circle, and means the longest portion when the cross-sectional shape is deformed such as an ellipse. Furthermore, as the shape of the particles having mesopores, various shapes such as a spherical shape, an irregular shape, and a rod shape are applicable. The particle size of the particles is not particularly limited, and may be any size as long as it is excellent in miscibility with the electrolyte and has a cell gap or less. In general, if it is too large, the photoelectric conversion efficiency of the battery is lowered. On the other hand, if it is too small, the holding power of the electrolyte may be lowered. Specifically, the thickness is preferably 300 nm to 1 μm. In addition, the particle diameter here means the particle diameter of the longest part when the particles are other than spherical.

Information on the pore size of the particles can be obtained by a nitrogen adsorption method. Specifically, the pore size distribution can be determined by the Berret-Joyner-Halenda (BJH) method from the results of nitrogen gas adsorption measurement. The average pore diameter suitably used in the present invention is preferably 1 to 20 nm, and more preferably 2 to 10 nm. Moreover, it is preferable that the specific surface area and pore volume of particle | grains measured by a nitrogen adsorption method are 400-1500 m < ² > / g and 0.1-3.0 cm < ³ > / g, respectively.

  Examples of the metal oxide particles having mesopores as described above include mesoporous titanium oxide, zinc oxide, cerium oxide, iron oxide, silica, alumina, and the like. Among these, mesoporous silica is particularly preferable because of its high porosity and excellent mechanical properties.

  The metal oxide particles having mesopores can be obtained by various conventionally known methods depending on the type. For example, mesoporous silica is generally produced using a sol-gel method using a surfactant as a template. Specifically, a surfactant is first dissolved in an aqueous solution at a concentration equal to or higher than the critical micelle concentration, and micelle particles having a certain size and structure are formed according to the type of the surfactant. When this is left standing for a while, the micelle particles take a packed structure and become colloidal crystals. Therefore, when tetraethoxysilane or the like serving as a silica source is added to the solution and a small amount of acid or base is added as a catalyst, The sol-gel reaction proceeds and a silica gel skeleton is formed. By baking this at a high temperature, the surfactant used as a template is decomposed and removed, and pure mesoporous silica can be obtained.

  Examples of the conductive particles having mesopores include particles such as carbon black having mesopores, artificial graphite, carbon nanotubes and multi-walled carbon nanotubes, and mesoporous metal particles.

  For example, mesoporous metal particles form a large-sized molecular assembly by self-organizing an amphiphilic block copolymer, and this molecular assembly is directly used as a template, under precise control of electrolytic deposition conditions. It can be obtained by reducing metal ions.

  If the content of the metal oxide particles or conductive particles having mesopores in the electrolyte layer 30 is too large, the coating property of the electrolyte forming coating solution is lowered, and conversely if the content is too small, the holding power of the electrolyte solution is reduced. Since it cannot be obtained, it is appropriately set in consideration of these. Specifically, the total amount of particles having mesopores is preferably 5 to 20 parts by weight with respect to 100 parts by weight of the electrolytic solution composed of the redox couple and the ionic liquid. However, it is also possible to add 20 parts by weight or more by diluting the coating solution with an organic solvent or the like and volatilizing the organic solvent after coating as an electrolyte layer.

  The electrolyte layer 30 may further contain a polymer material as necessary. The polymer material holds a redox couple and an ionic liquid and forms a stable solid electrolyte layer. Examples of such a polymer material include cellulose derivatives, polyester resins, polyamide resins, polyacrylate resins, polymethacrylate resins such as polymethyl methacrylate, polycarbonate resins, polyurethane resins, and polyolefin resins. Examples thereof include resins, polyvinyl acetal resins, fluorine resins such as polyvinylidene fluoride, polyimide resins, and polyhydric alcohols such as polyethylene glycol. These may be used alone or in combination. Among these, cellulose derivatives, polymethacrylic ester resins, and fluororesins are preferably used, and cellulose derivatives are particularly preferably used because they are excellent in redox pair and ionic liquid retention.

  Examples of cellulose derivatives include methyl cellulose, ethyl cellulose, hydroxypropyl cellulose and the like, and among them, ethyl cellulose is preferably used.

  The molecular weight of the polymer material varies depending on the type and is not particularly limited. For example, when ethyl cellulose is used as the polymer material, the molecular weight is 10 to 1000 mPa · s at a value obtained by dissolving ethyl cellulose at 5% by weight in an ethanol solvent and measuring the viscosity at 25 ° C. It is preferable that

  If the concentration of the polymer material in the electrolyte layer 30 is too large, the photoelectric conversion efficiency of the solar cell is lowered. Specifically, it can be contained in the electrolyte layer 30 in an amount of 30% by weight or less.

  In addition, the electrolyte layer 30 can contain various additives for the purpose of improving durability, improving open-circuit voltage value, and the like. Specific examples of the additive include guanidinium thiocyanate, tertiary butyl pyridine, N-methylbenzimidazole and the like. The concentration of these additives in the electrolyte layer is preferably 1 mol / l or less in the electrolyte layer by adding the various additives.

  The thickness of the electrolyte layer 30 is preferably in the range of 2 μm to 150 μm including the thickness of the porous semiconductor layer 20, and preferably in the range of 10 μm to 50 μm. If the film thickness is too small, the porous semiconductor layer and the counter electrode base material may come into contact with each other and cause a short circuit. On the other hand, if the film thickness is too large, the internal resistance increases and the performance is deteriorated.

  As a method for forming the electrolyte layer 30, a method of forming a coating liquid used for forming the electrolyte layer by applying it on the porous semiconductor layer 20 and drying it (hereinafter referred to as a coating method), or a porous semiconductor. A method of forming an electrolyte layer by arranging the electrode substrate 10 on which the layer 20 is formed and the counter electrode substrate 40 so as to have a predetermined gap and injecting a coating liquid into the gap (hereinafter referred to as an injection method). Etc.

  The coating liquid can be diluted with a solvent as necessary. Examples of the solvent include alcohol solvents such as ethanol, ketone solvents such as methyl ethyl ketone, amide solvents such as N-methylpyrrolidone, and pure water.

  In the coating method, known means can be used as means for applying the coating liquid onto the porous semiconductor layer 20, and specifically, die coating, gravure coating, gravure reverse coating, roll coating, reverse roll coating. , Bar coating, blade coating, knife coating, air knife coating, slot die coating, slide die coating, dip coating, micro bar coating, micro bar reverse coating, screen printing, and the like. After coating, when the solvent is contained, the electrolyte layer can be formed by drying it appropriately and removing the solvent.

  When the coating liquid contains a polymer material, it contains a crosslinking agent, a photopolymerization initiator, etc. as additives, and after applying the coating liquid on the porous semiconductor layer, the electrolyte layer is irradiated with light. May be cured.

  The dye-sensitized solar cell of the present invention can be obtained by bonding the catalyst layer side of the counter electrode substrate 40 to the electrolyte layer 30 thus formed.

  When the electrolyte layer 30 is formed by an injection method, first, the electrode base material 10 and the counter electrode base material 40 on which the porous semiconductor layer 20 is formed are arranged so as to face each other with a predetermined gap. The gap at this time is preferably set so that the distance between the electrode substrate 10 and the counter electrode substrate 40 is 2 μm to 150 μm. In order to arrange the counter electrode base material 40 with a predetermined gap, a spacer can be provided on either the electrode base material 10 side or the counter electrode base material 40 side. Examples of such a spacer include known glass spacers and resin spacers.

  Next, a coating solution used for forming the electrolyte layer is injected into the gap by utilizing a capillary phenomenon or the like, and is optionally cured by performing temperature adjustment, ultraviolet irradiation, electron beam irradiation, or the like. Can be formed. Thereby, a dye-sensitized solar cell can be obtained.

  Furthermore, a dye-sensitized solar cell module can be obtained by connecting a plurality of the dye-sensitized solar cells 1 obtained as described above in series or in parallel. Specifically, for example, a plurality of dye-sensitized solar cells are arranged in a planar shape or a curved shape, and each cell is electrically connected using a conductive member, and the positive or negative electrode is connected from the end. The electrode lead can be pulled out and modularized. The number of dye-sensitized solar cells constituting the module is arbitrary, and can be freely designed so as to obtain a desired voltage.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, it is not limited to this.

Example 1
-Preparation of electrolyte solution Volume of 1-ethyl-3-methylimidazolium-tetracyanoborate (EMIm-B (CN4)) and 1-methyl-3-n-propylimidazolium iodide (MPImI) as ionic liquids Mixed at a ratio of 7:13 (91.4% by weight), further dissolved in an amount of 0.2 mol / l iodine, 0.1 mol / l guanidinium thiocyanate, 0.5 mol / l N-methylbenzimidazole (NMBI) To prepare an electrolytic solution.

-Production of electrolyte forming coating solution 10 parts by weight of mesoporous silica filler (manufactured by Admatechs) was added to 100 parts by weight of the electrolyte solution to obtain a gel-like electrolyte forming coating solution. The mesoporous silica filler used had an average particle size of 530 nm and a pore size of 4 nm.

-Preparation of electrode substrate and porous semiconductor layer As a transparent electrode substrate, transparent conductive glass (manufactured by Nippon Sheet Glass Co., Ltd.) with an FTO film (fluorine-doped tin oxide) formed on a glass plate is prepared, and titanium oxide paste Nanooxide
A porous semiconductor having a film thickness of 10 μm formed by a large number of semiconductor fine particles (TiO ₂ fine particles) formed by applying D-SP (manufactured by solaronix) to a 4 mm square pattern by screen printing and firing at 550 ° C. A layer was obtained. Thereafter, a ruthenium complex (manufactured by Dyesole; N719) as a sensitizing dye was dissolved in a solvent having a volume ratio of acetonitrile and tert-butyl alcohol of 1: 1 so that the concentration was 3 × 10 ⁻⁴ mol / l. The porous semiconductor layer described above was immersed in the solution at room temperature for 20 hours. Next, the porous semiconductor layer was pulled up from the dye-carrying solution, and the attached dye-carrying solution was washed with acetonitrile and then air-dried. As a result, a sensitizing dye was supported on the surface of the titanium oxide fine particles forming the porous semiconductor layer, and an electrode substrate (with a porous semiconductor layer) having a substrate size of 10 mm □ was obtained.

-Production of counter electrode base material A platinum film (film thickness of 300 nm) was formed on the above-mentioned transparent conductive glass by a sputtering method to produce a 10 mm □ counter electrode base material.

-Formation of electrolyte layer The said gel-like coating liquid was apply | coated with the pattern of 4 mm (square) on the porous semiconductor layer by the screen-printing method, and the electrolyte layer was formed.

-Cell assembly On the outer periphery of the formed electrolyte layer, a square frame ionomer resin cut out at 6 mm □ and then punched out at a size of 5 mm □ was placed, and a counter electrode base material was bonded. Next, the ionomer resin was melted and bonded on a 105 ° C. hot plate to obtain the target dye-sensitized solar cell.

(Example 2)
A dye-sensitized solar cell was produced in the same manner as in Example 1 except that a particle size of 530 nm and a pore size of 2.7 nm were used as the mesoporous silica filler.

(Comparative Example 1)
A dye-sensitized solar cell was produced in the same manner as in Example 1 except that a coating liquid to which a 12 nm non-porous spherical silica filler was added was used.

(Comparative Example 2)
A dye-sensitized solar cell was produced in the same manner as in Example 1 except that a particle size of 530 nm and a pore size of 1.8 nm were used as the mesoporous silica filler.
The results of Examples 1 and 2 and Comparative Examples 1 and 2 are shown in Table 1.

(Performance comparison)
For the dye-sensitized solar cells produced in Examples 1 and 2, the conversion efficiency was determined using pseudo-sunlight AM1.5 and incident light intensity of 100 mW / cm ² ) as the light source, and η = 5.57% and 5 respectively. 51%. On the other hand, the dye-sensitized solar cell of Comparative Example 1 had η = 5.65%. Therefore, the performance equivalent to the conventional gel electrolyte was confirmed.

  When the electrolyte layer produced in Examples 1 and 2 was held at 85 ° C. for 1000 hours, the electrolyte component did not ooze out and no change was observed in the viscosity of the gel electrolyte. On the other hand, the electrolyte layer produced in Comparative Example 1 was confirmed to seep out of the electrolytic solution component, and the electrolyte layer was reduced to a viscosity of about the electrolytic solution made of an ionic liquid. Further, in Comparative Example 2, the electrolyte component oozed out and separated from the particles with time. This is presumably because the electrolyte was not able to enter the pores because the pore diameter was too small.

1 Dye-sensitized solar cell 10 Electrode base material 20 Porous semiconductor layer 30 Electrolyte layer 40 Counter electrode base material

Claims (4)

A coating solution for forming an electrolyte of a dye-sensitized solar cell, comprising at least an electrolyte solution comprising a redox couple and an ionic liquid, and mesoporous silica having mesopores . Having mesopores, mesoporous silica, the electrolyte forming coating liquid according to claim 1 which contains 5 to 20 parts by weight based on the electrolyte solution 100 parts by weight. Electrode substrate, porous semiconductor layer formed on electrode substrate with sensitizing dye supported on pore surface, counter electrode substrate disposed opposite to porous semiconductor layer, electrode substrate and counter electrode The dye-sensitized solar cell comprised from the electrolyte layer formed from the coating liquid of Claim 1 or 2 arrange | positioned between base materials. A dye-sensitized solar cell module comprising a plurality of the dye-sensitized solar cells according to claim 3 connected in series or in parallel.

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