JP5189870B2 - Electrolytic solution and dye-sensitized solar cell - Google Patents

Description

  The present invention relates to an electrolytic solution and a dye-sensitized solar cell.

Known electrolyte solutions for dye-sensitized solar cells use organic solvents and ionic liquids. By using the ionic liquid, it is expected that the durability is improved as compared with the case of using the organic solvent. For example, a dye-sensitized solar cell composed of an electrolytic solution containing an ionic liquid and N-methyl-benzimidazole has been reported (Non-Patent Document 1).
Kuang D. et. al. , J .; AM. CHEM. SOC. 128, 7732-7733 (2006)

  However, a dye-sensitized solar cell using an electrolytic solution using an ionic liquid has insufficient photocurrent and photoelectric conversion efficiency.

  Accordingly, an object of the present invention is to provide an electrolytic solution using an ionic liquid that makes it possible to obtain a dye-sensitized solar cell having high photocurrent and photoelectric conversion efficiency.

  As a result of intensive studies to solve the above problems, the inventors have found that it is effective to add a nonionic organic compound to the electrolytic solution, and have completed the present invention.

  That is, the present invention relates to an electrolytic solution containing iodine and an iodine compound that is an ionic liquid containing iodine ions, and further containing a nonionic organic compound that lowers the viscosity of the electrolytic solution.

  Such an electrolytic solution can obtain high photocurrent and photoelectric conversion efficiency when used in a dye-sensitized solar cell, despite containing an ionic liquid. Moreover, durability and heat resistance are also favorable.

  The electrolytic solution of the present invention may further contain an ionic liquid having a viscosity of 5 to 30 mPa · s, in addition to the iodine compound. Thereby, when this electrolyte solution is used for a dye-sensitized solar cell, photocurrent and photoelectric conversion efficiency are further improved.

  The nonionic organic compound preferably has a boiling point of 220 ° C. or higher under atmospheric pressure. By adding such an organic compound, the durability and heat resistance of the dye-sensitized solar cell using this electrolytic solution are further improved.

  The nonionic organic compound is preferably at least one compound selected from the group consisting of a bifunctional nitrile compound, a polyethylene glycol dialkyl ether, and a phthalate ester. By adding these organic compounds to the electrolytic solution, the photocurrent of the dye-sensitized solar cell using this electrolytic solution is further increased, and the photoelectric conversion efficiency is further improved.

  The electrolytic solution of the present invention may further contain a benzimidazole derivative having a benzimidazole ring and a saturated hydrocarbon group which may be directly bonded to the benzimidazole ring. By adding such a benzimidazole derivative, the photovoltaic voltage at the open end of the dye-sensitized solar cell using this electrolytic solution is further improved. This is considered to be because leakage current is reduced by preventing reverse electron transfer from the titanium oxide to the electrolytic solution by the benzimidazole derivative. Further, the durability of the dye-sensitized solar cell using this electrolytic solution is further improved.

  The electrolytic solution of the present invention may further contain a guanidine salt. By adding the guanidine salt to the electrolytic solution, when this electrolytic solution is used in a dye-sensitized solar cell, it is possible to further increase the photoelectric current and further increase the initial photoelectric conversion efficiency.

  Moreover, this invention provides a dye-sensitized solar cell provided with said electrolyte solution. Since the dye-sensitized solar cell of the present invention has high photocurrent and photoelectric conversion efficiency, it is excellent in practicality.

  According to the present invention, when used in a dye-sensitized solar cell, an electrolytic solution using an ionic liquid that makes it possible to obtain a dye-sensitized solar cell with improved photocurrent and photoelectric conversion efficiency. Can be provided. Moreover, this electrolyte solution is also excellent in terms of durability and heat resistance.

  Hereinafter, preferred embodiments will be described with reference to the drawings as necessary. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. In addition, the drawings are exaggerated for easy understanding, and the dimensional ratios do not necessarily match those described.

(First embodiment)
FIG. 1 is a cross-sectional view showing a dye-sensitized solar cell 20 according to the first embodiment. The dye-sensitized solar cell 20 includes the electrolytic solution E of the present invention as described later.

  The dye-sensitized solar cell 20 mainly includes a photoelectrode 10, a counter electrode CE, a seal material 5 sandwiched between the photo electrode 10 and the counter electrode CE, and a space between the photo electrode 10 and the counter electrode CE by the seal material 5. And an electrolytic solution E filled in the gap formed in the above.

The photoelectrode 10 is mainly attached to the semiconductor electrode 2 having the light receiving surface F2, the transparent electrode (transparent conductive substrate) 1 disposed adjacent to the light receiving surface F2 of the semiconductor electrode 2, and the semiconductor electrode 2. And a sensitizer. The semiconductor electrode 2 is mainly composed of titanium oxide particles. Specifically, the sensitizer is adsorbed on the titanium oxide particles. The semiconductor electrode 2 is in contact with the electrolytic solution E. In addition, the electrolytic solution E has also permeated into the pores of the titanium oxide particles of the semiconductor electrode 2. Here, as the titanium oxide, anatase TiO ₂ is preferable to rutile TiO ₂ because the energy level at the lower end of the conduction band is higher and the open-circuit voltage is higher.

  In the dye-sensitized solar cell 20, the sensitizer adsorbed on the titanium oxide particles in the semiconductor electrode 2 is excited by light transmitted through the transparent electrode 1 and irradiated on the semiconductor electrode 2, and this sensitization is performed. Electrons are injected from the agent into the titanium oxide particles in the semiconductor electrode 2. The electrons injected into the titanium oxide particles in the semiconductor electrode 2 are collected by the transparent electrode 1 and taken out to the outside.

  As the transparent electrode 1, a transparent electrode mounted on a normal dye-sensitized solar cell or an inorganic solid solar cell can be used. The transparent electrode 1 has a configuration in which a transparent conductive film 3 is laminated on the semiconductor electrode 2 side of a transparent substrate 4 made of, for example, a conductive glass substrate. As the transparent conductive film 3, a transparent conductive film used for a liquid crystal panel or the like may be used.

Examples of the transparent electrode 1 include fluorine-doped SnO ₂ coated glass, ITO coated glass, ZnO: Al coated glass, and antimony-doped tin oxide (SnO ₂ —Sb). Also, a transparent electrode obtained by doping tin oxide or indium oxide with cations or anions having different valences, or a metal electrode having a structure capable of transmitting light, such as a mesh shape or a stripe shape, provided on a substrate such as a glass substrate. It can be used as a transparent electrode.

  As the transparent substrate 4, a transparent substrate used for a liquid crystal panel or the like may be used. Specific examples of the transparent substrate include a transparent glass substrate, a substrate in which the surface of the glass substrate is appropriately roughened to prevent reflection of light, and a substrate that transmits light such as a ground glass-like translucent glass substrate. The transparent substrate 4 may be a transparent plastic plate, a transparent plastic film, an inorganic transparent crystal, or the like as long as it transmits light, but is preferably transparent glass.

  The sensitizer attached to the semiconductor electrode 2 is not particularly limited as long as it is a sensitizer having absorption in the visible light region and / or the infrared light region. The sensitizer preferably emits electrons when excited with light having a wavelength of 200 nm to 10 μm.

  Here, the sensitizer includes an organic dye. The organic dye refers to a metal complex, an organic dye or the like. Metal complexes include metal phthalocyanines such as copper phthalocyanine and titanyl phthalocyanine, chlorophyll or derivatives thereof, hemin, ruthenium, osmium, iron and zinc complexes (eg cis-dicyanate-N, N′-bis (2,2′-bipyridyl) -4,4'-dicarboxylate) ruthenium (II)) and the like. As the organic dye, metal-free phthalocyanine, cyanine dye, merocyanine dye, xanthene dye, triphenylmethane dye, and the like can be used.

  The counter electrode CE is not particularly limited as long as it is composed of a material capable of causing a reduction reaction to obtain a reductant by causing electrons to react with an oxidant of a redox pair contained in the electrolyte E. For example, the same transparent electrode as that normally used for a silicon solar cell, a liquid crystal panel, or the like can be used.

  As the counter electrode CE, for example, one having the same configuration as that of the transparent electrode 1 described above is used, and is arranged so that the transparent conductive film (not shown) side is in contact with the electrolytic solution E. In addition, as the counter electrode CE, a metal thin film electrode such as Pt may be formed on the transparent conductive film 3 similar to the transparent electrode 1, and the metal thin film electrode may be arranged facing the electrolyte E side. . Moreover, the thing which adhered a small amount of platinum to the transparent conductive film 3 of the transparent electrode 1 or a metal thin film such as platinum can be used as the counter electrode CE. Further, a porous carbon electrode may be used as a counter electrode.

The electrolytic solution E contains iodine (I ₂ ), an iodine compound that is an ionic liquid containing iodine ions (I ⁻ ), and a nonionic organic compound that lowers the viscosity of the electrolytic solution.

  The concentration of iodine in the electrolytic solution E is preferably 0.01 to 0.5 mol / L.

  An example of an iodine compound that is an ionic liquid containing iodine ions is propylmethylimidazolium iodide (hereinafter abbreviated as PMII). The concentration of the iodine compound that is an ionic liquid containing iodine ions in the electrolytic solution E is preferably 0.05 to 5 mol / L.

  As the nonionic organic compound, an organic compound that lowers the viscosity of the electrolytic solution E as compared with the case where it is not added is used. This organic compound can be appropriately selected from those which can be dissolved in, for example, an ionic liquid and have a low viscosity. More specifically, it is more preferably at least one compound selected from the group consisting of a bifunctional nitrile compound, polyethylene glycol dialkyl ether, and phthalate ester. Examples of the bifunctional nitrile compound include dimethylmalononitrile and adiponitrile. The boiling point of dimethylmalononitrile is 120 ° C. under a pressure of 33 mmHg (about 4.4 kPa). The boiling point of adiponitrile is 295 ° C. under atmospheric pressure. Examples of the polyethylene glycol dialkyl ether include tetraethylene glycol dimethyl ether and triethylene glycol dimethyl ether. Tetraethylene glycol dimethyl ether has a boiling point of 276 ° C. under atmospheric pressure. The boiling point of triethylene glycol dimethyl ether is 227 ° C. under atmospheric pressure. The phthalic acid ester is more preferably an alkyl phthalic acid ester, and examples thereof include dimethyl phthalate and diethyl phthalate. The boiling point of dimethyl phthalate is 282 ° C. under atmospheric pressure. The boiling point of diethyl phthalate is 299 ° C. under atmospheric pressure.

  The inventors have found that the photocurrent and photoelectric conversion efficiency of the dye-sensitized solar cell 20 using the electrolytic solution E are improved by adding the nonionic organic compound to the electrolytic solution E. . This is presumed to be due to the following reason. That is, an iodine compound which is an ionic liquid containing iodine ions has a high viscosity. For example, PMII has a viscosity of 130 mPa · s. For this reason, the dye-sensitized solar cell 20 using the electrolytic solution E containing an iodine compound which is an ionic liquid containing iodine ions has a large diffusion resistance of iodine ions and an interface resistance between the electrolytic solution E and the photoelectrode. This is considered to be a cause of a decrease in photocurrent and photoelectric conversion efficiency. Therefore, by adding the above nonionic organic compound to the electrolytic solution E, the viscosity of the electrolytic solution E is lowered, and the diffusion resistance of iodine ions in the dye-sensitized solar cell 20 using the electrolytic solution E and the electrolysis are reduced. It is considered that the photoelectric resistance of the dye-sensitized solar cell 20 is increased and the photoelectric conversion efficiency is improved by reducing the interface resistance between the liquid E and the photoelectrode.

  In addition, the dye-sensitized solar cell 20 using the electrolytic solution E to which the nonionic organic compound is added is excellent in heat resistance and durability. This is presumed to be due to the following reason. That is, since the nonionic organic compound has a boiling point of 220 ° C. or higher under atmospheric pressure and a high boiling point, it is considered that the volatility of the electrolytic solution E to which the nonionic organic compound is added is reduced. As a result, it is considered that the evaporation of the electrolyte solution E, which is one of the causes of reducing the durability of the dye-sensitized solar cell 20, is suppressed, and the durability is improved. Moreover, since the nonionic organic compound has a high boiling point, it is considered that the heat resistance of the electrolytic solution E to which the nonionic organic compound is added is improved.

  The ratio of the nonionic organic compound that decreases the viscosity of the electrolytic solution in the electrolytic solution E is 100 wt% of the total of the iodine compound that is an ionic liquid containing iodine ions and the nonionic organic compound. In some cases, it is preferably 20 to 80 wt%, more preferably 30 to 60 wt%, and particularly preferably 40 to 50 wt%.

  In addition, the electrolytic solution E preferably further contains an ionic liquid having a viscosity of 5 to 30 mPa · s, in addition to the iodine compound. Thereby, in the dye-sensitized solar cell 20 using the electrolytic solution E, the photocurrent and the photoelectric conversion efficiency can be further improved. This is presumed to be due to the following reason. That is, by adding an ionic liquid having a viscosity of 5 to 30 mPa · s, the nonionic organic compound for reducing the viscosity described above and the ionic liquid having a viscosity of 5 to 30 mPa · s act synergistically to In the dye-sensitized solar cell 20 using the electrolytic solution E, the viscosity is further lowered, and the diffusion resistance of iodine ions and the interface resistance between the electrolytic solution and the photoelectrode are further reduced, resulting in an increase in photocurrent and photoelectric conversion efficiency. it is conceivable that.

  In addition, by adding an ionic liquid having a viscosity of 5 to 30 mPa · s to the electrolytic solution E, the durability of the dye-sensitized solar cell 20 using the electrolytic solution E is further improved. This is presumed to be due to the further decrease in the volatility of the entire electrolyte E since the ionic liquid is non-volatile.

  Examples of ionic liquids having a viscosity of 5 to 30 mPa · s include ethylmethylimidazolium bis (trifluoromethanesulfonyl) imide, ethylmethylimidazolium bis (fluorosulfonyl) imide, allylmethylimidazolium bis (trifluoromethanesulfonyl) imide, ethylmethyl Examples thereof include imidazolium salts such as imidazolium tetracyanoborate.

  The ratio of the ionic liquid having a viscosity of 5 to 30 mPa · s in the electrolytic solution E is 100 wt% of the total of the iodine compound that is an ionic liquid containing iodine ions and the ionic liquid having a viscosity of 5 to 30 mPa · s. In some cases, it is preferably 20 to 60 wt%.

  Moreover, it is preferable that the electrolyte solution E further contains the benzimidazole derivative which has a benzimidazole ring and the saturated hydrocarbon group which may have a substituent directly couple | bonded with this. By adding such a benzimidazole derivative, the durability of the dye-sensitized solar cell using this electrolytic solution is further improved. The saturated hydrocarbon group preferably has 1 to 11 carbon atoms, and more preferably 3 to 11 carbon atoms. The saturated hydrocarbon group may be linear or branched, but is more preferably linear. Further, the saturated hydrocarbon group may have a hydroxyl group or an aldehyde group, but more preferably does not have a hydroxyl group or an aldehyde group. If there is a hydroxyl group or an aldehyde group, it may easily react with moisture in the electrolytic solution E, and the effect of improving durability may be reduced. More specifically, the benzimidazole derivative preferably has a structure represented by the following general formula (I). In the formula, R is a saturated hydrocarbon group which may have a substituent.

  The concentration of the benzimidazole derivative in the electrolytic solution E is preferably 0.2 to 0.8 mol / L.

  Moreover, it is preferable that the electrolyte solution E further contains a guanidine salt. When the electrolytic solution E to which a guanidine salt is added is used for a dye-sensitized solar cell, the initial photoelectric conversion efficiency can be further increased. An example of a guanidine salt is guanidine thiocyanate. The concentration of the guanidine salt in the electrolytic solution E is preferably 0.2 to 0.8 mol / L.

  The sealing material 5 is for preventing the electrolyte E from leaking outside from the side surfaces of the semiconductor electrode 2 and the counter electrode CE. As the sealing material 5, for example, a thermoplastic resin film such as polyethylene or an epoxy adhesive can be used.

  For the purpose of sealing the electrolytic solution E, as an adhesive used to integrate the photoelectrode 10 and the counter electrode CE with respect to the sealing material 5, the component of the electrolytic solution E is not leaked to the outside as much as possible. It is not particularly limited as long as it can be sealed. For example, an epoxy resin, a silicone resin, an ethylene / methacrylic acid copolymer, a thermoplastic resin made of surface-treated polyethylene, or the like can be used.

  Next, a method for manufacturing the dye-sensitized solar cell 20 will be described.

First, the transparent electrode 1 is prepared. The transparent electrode 1 can be formed on the transparent substrate 4 such as a TCO glass substrate by using the above-described transparent conductive film 3 such as fluorine-doped SnO ₂ using a known thin film manufacturing technique such as a spray coating method. . The transparent conductive film 3 can be formed using a known thin film manufacturing technique such as a vacuum deposition method, a sputtering method, a CVD method, and a sol-gel method in addition to the spray coating method.

  Next, the semiconductor electrode 2 is formed on the transparent conductive film 3 of the transparent electrode 1. The semiconductor electrode 2 is formed as follows.

  First, a titanium oxide particle-containing composition containing titanium oxide particles, a dispersant, a thickener, a solvent, and the like is prepared. And this titanium oxide particle containing composition is apply | coated on the transparent conductive film 3 of the transparent electrode 1, and is baked. Thus, the semiconductor electrode 2 is formed on the transparent conductive film 3 of the transparent electrode 1.

  Here, examples of the method for applying the titanium oxide particle-containing composition include a bar coater method and a printing method.

  The firing temperature depends on the composition of the titanium oxide particle-containing composition and cannot be generally specified, but is usually 300 to 600 ° C, and preferably 400 to 600 ° C. Firing is usually performed in an oxidizing atmosphere such as air.

  Next, a sensitizer is attached to the semiconductor electrode 2 by a known technique such as an adhesion method. Thus, the photoelectrode 10 is obtained. At this time, the sensitizer may be attached by adhering to the semiconductor electrode 2 (chemical adsorption, physical adsorption or deposition). As this adhesion method, for example, a method of immersing the photoelectrode 10 in a solution containing a pigment can be used. At this time, adsorption and deposition of a sensitizer (for example, sensitizing dye) can be promoted by heating and refluxing the solution. At this time, in addition to the dye, a metal such as silver or a metal oxide such as alumina may be attached to the semiconductor electrode 2 as necessary.

  Next, a counter electrode CE is formed separately. Here, the manufacturing method of counter electrode CE is not specifically limited, It can manufacture by a well-known method. For example, when the counter electrode CE has the same configuration as that of the transparent electrode 1, the counter electrode CE may be manufactured in the same manner as the method for manufacturing the transparent electrode 1 described above.

  Next, a substrate (not shown) is disposed on the surface of the counter electrode CE opposite to the semiconductor electrode 2, and the side surfaces of the semiconductor electrode 2 and the counter electrode CE are covered with the sealing material 5. Next, the electrolytic solution E is injected into the gap formed between the semiconductor electrode 2 and the photoelectrode 10 and the counter electrode CE.

  The injection of the electrolytic solution E can be performed, for example, using the photoelectrode 10, the counter electrode CE, or an injection port provided in advance in the sealing material 5. The injection port is closed by a predetermined member or resin after the injection of the electrolytic solution E is completed. Thus, the dye-sensitized solar cell 20 is obtained.

(Second Embodiment)
FIG. 2 is a cross-sectional view showing a dye-sensitized solar cell according to the second embodiment. In addition, the same code | symbol is attached | subjected about the component same as the solar cell 20 of 1st Embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 2, in the solar cell 30 of the present embodiment, a porous body layer PS having a structure having a large number of pores is introduced between the semiconductor electrode 2 and the counter electrode CE, and the shape of the counter electrode CE is further increased. And it has the structure similar to the solar cell 20 of 1st Embodiment except having set it as the following.

  That is, the porous body layer PS is not particularly limited as long as it is capable of holding the electrolytic solution E and does not have electron conductivity. For example, a porous body formed of rutile titanium oxide particles may be used as the porous body layer PS. Examples of constituent materials other than rutile type titanium oxide include zirconia, alumina, and silica. Further, the porous layer PS also has a function as a light reflecting layer that reflects light transmitted through the photoelectrode 10 and irradiates the reflected light into the photoelectrode 10 again. Thereby, the utilization efficiency of the light in the photoelectrode 10 can be improved. The electrolytic solution E is also held in the semiconductor electrode 2. Further, when the counter electrode CE is a porous carbon electrode, it is also held in the counter electrode CE. Here, the porous body layer PS has a portion that covers the back surface F22 of the semiconductor electrode 2, and a bowl-shaped edge portion that covers and closely covers the side surface of the semiconductor electrode 2 adjacent to the back surface F22. The flange-shaped edge portion penetrates through the transparent electrode 1 of the photoelectrode 10 and is in contact with the transparent substrate 4. Specifically, the bowl-shaped edge portion extends in the normal direction of the light receiving surface F <b> 1 of the transparent electrode 1 and is electrically connected to the transparent electrode 1.

  The connecting portion between the transparent electrode 1 and the porous layer PS will be described in more detail. In this connecting portion, a part of the transparent conductive film 3 of the transparent electrode 1 is completely scraped by a technique such as laser scribing. A groove 9 having a depth at which the surface of the transparent substrate 4 is exposed is formed. And the edge part formed in the groove | channel shape of the porous body layer PS in the part of this groove | channel 9 is inserted.

  Next, the counter electrode CE will be described. In the solar cell 20 shown in FIG. 1, an electrode having the same configuration as the transparent electrode 1 is adopted as the counter electrode CE, whereas in the solar cell 30 according to the present embodiment, a conductive carbon material is used as the counter electrode CE. Is used as a constituent material.

  The counter electrode CE (carbon electrode) is a porous electrode formed using, for example, carbon black particles, graphite particles, and conductive oxide particles such as anatase-type titanium oxide particles as constituent materials. The electrolyte solution E is held in the pores of the porous counter electrode CE (carbon electrode). In the counter electrode CE, which is a porous carbon electrode, for example, catalyst fine particles such as Pt fine particles may be dispersed and supported from the viewpoint of allowing the speed of the electrode reaction to proceed more rapidly.

  This counter electrode CE (carbon electrode) also has a bowl-like shape for adhering and covering a part of the porous layer PS that covers the part covering the back surface F22 of the semiconductor electrode 2 and a bowl-shaped edge part of the porous layer PS. And an edge portion. The saddle-like edge portion of the counter electrode CE (carbon electrode) also extends in the normal direction of the light receiving surface F1 of the transparent electrode 1 of the photoelectrode 10, and the tip thereof is in close contact with the surface of the transparent conductive film 3 of the transparent electrode 1. To be connected.

  Furthermore, the moisture-proof film 7 is disposed adjacent to the surface of the counter electrode CE (carbon electrode) opposite to the porous body layer PS. Further, the portion of the side surface of the semiconductor electrode 2 not covered with the bowl-shaped edge portion of the porous body layer PS and the side surface of the porous body layer PS are not covered with the bowl-shaped edge portion of the counter electrode CE. The portion is sealed by bringing a sealing material 5 similar to that used in the solar cell 20 shown in FIG. Further, the sealing material 5 is disposed so as to be in close contact with the outer surface of the bowl-shaped edge portion of the counter electrode CE. Thus, by disposing the moisture-proof film 7 and the sealing material 5, the electrolyte contained in each of the semiconductor electrode 2 and the porous body layer PS is sufficiently prevented from escaping to the outside of the battery 40. The

  As described above, the solar cell 30 has a configuration in which the porous layer PS and the counter electrode CE are integrated with the transparent electrode 1 of the photoelectrode 10. And the electrical contact with the photoelectrode 10 and the counter electrode CE is prevented by the bowl-shaped edge part of the porous body layer PS. If the electrical contact between the photoelectrode 10 and the counter electrode CE (electron transfer between the photoelectrode 10 and the counter electrode CE) is sufficiently prevented, the bowl-shaped porous layer PS in FIG. The side surface of the semiconductor electrode 2 and the inner side surface of the bowl-shaped edge portion of the counter electrode CE may be apparently in contact with each other without providing the edge portion. In this case, the constituent material of the semiconductor electrode 2 is inserted into the groove 9.

  Next, a method for manufacturing the solar cell 30 will be described.

  First, the transparent electrode 1 is prepared. The method for forming the transparent electrode 1 is basically the same as the method for manufacturing the transparent electrode 1 described in the method for manufacturing the solar cell 20 described above. However, in this embodiment, after forming the transparent conductive film 3 on the transparent substrate 4, a part of the transparent conductive film 3 is shaved by laser scribing to expose the surface of the transparent substrate 4, and the inside of the filler This is different from the method for forming the transparent electrode 1 in the first embodiment in that the groove 9 (see FIG. 2) in the absence of the groove is formed.

  After forming this groove | channel 9, the precursor layer (or semiconductor electrode 2) of the semiconductor electrode 2 is formed on the transparent conductive film 3 of the transparent electrode 1 (1st process). In this case, the above-described titanium oxide particle-containing composition is applied on the surface of the transparent conductive film 3 so as to avoid the grooves 9, and the semiconductor electrode 2 is formed by firing or ultraviolet irradiation. However, at this time, the precursor layer (or the semiconductor electrode 2) of the semiconductor electrode 2 is also formed in the groove 9, and then the precursor layer (or the semiconductor electrode 2 filling the groove 9 by laser scribing) (or The portion of the semiconductor electrode 2) may be scraped off, and the surface of the transparent substrate 4 may be exposed again to form the groove 9 (see FIG. 2) without any filler inside.

  Next, a liquid containing an insulating porous material is prepared, and the liquid is applied onto the semiconductor electrode 2 and then dried, so that the semiconductor electrode 2 and the porous layer PS formed on the semiconductor electrode 2 are obtained. A laminate comprising the precursor layer is obtained. Here, the precursor layer (or porous layer PS) of the porous layer PS is prepared, for example, as a dispersion (slurry) containing a constituent material of the electrically insulating porous layer PS such as rutile titanium oxide. Then, it can be obtained by applying it on the surface F22 of the semiconductor electrode 2 and drying it.

  Here, after forming the precursor layer of the porous body layer PS, the precursor layer of the porous body layer PS is baked by further heat-treating in an oxidizing atmosphere such as in air at a temperature range of 400 to 600 ° C. The porous body layer PS may be formed. In this case, when the temperature of the heat treatment is less than 400 ° C., the tendency that the precursor layer cannot be sufficiently baked increases. Moreover, when the temperature of the heat treatment exceeds 600 ° C., the tendency of the electrical resistance of the transparent electrode 1 to increase increases and the transparent substrate 4 is distorted to cause the precursor layer of the porous layer PS (or the porous body after firing). Part or all of the layer PS) is exfoliated and the tendency of the battery performance to decrease increases.

  However, even if the heat treatment for firing the precursor layer of the porous body layer PS to form the porous body layer PS is omitted, the heat treatment of the precursor layer of the semiconductor electrode 2 and the precursor layer of the porous body layer is performed later. By carrying out collectively, the precursor layer of porous body layer PS can be baked and porous body layer PS can be formed. For this reason, from the viewpoint of improving the production efficiency, it is preferable to omit the heat treatment at this stage.

  In addition, when the groove | channel 9 is not formed in the transparent electrode 1 in the stage which preparation of the precursor layer (or semiconductor electrode 2) of the semiconductor electrode 2 was completed, the precursor layer of porous body layer PS by laser scribing process. A part of (or porous layer PS) may be shaved to expose the surface of the transparent substrate 4 and form a groove 9 (see FIG. 2) having no filler inside. At this time, the surface on the side where the counter electrode CE (carbon electrode) is formed is scraped out of the bowl-shaped edge portion of the porous body layer PS by the laser scribing process to adjust the shape of the porous body layer PS.

  Next, a liquid containing a conductive carbon material is prepared, and the liquid is applied onto the laminated body obtained as described above, and then dried, whereby the counter electrode CE (carbon electrode) is formed on the laminated body. A precursor layer is formed.

  The method for forming the counter electrode CE (carbon electrode) precursor layer is not particularly limited, and can be formed by the following method, for example. That is, a slurry containing carbon black particles, graphite particles, conductive oxide particles such as anatase-type titanium oxide particles, an organic solvent such as acetylacetone, ion-exchanged water, and a surfactant (or in this slurry) Carbon paste to which a thickener is added) is prepared, and this is applied onto the precursor layer of the porous body layer PS and dried. By repeating a series of operations of applying the slurry (or paste) and drying, the thickness of the obtained counter electrode CE (carbon electrode) can be adjusted.

  Here, after forming the precursor layer of the counter electrode CE (carbon electrode), the precursor layer of the porous body layer PS is fired by further heat treatment in a temperature range of 400 to 600 ° C. ) May be formed. In this case, when the temperature of the heat treatment is less than 400 ° C., there is a greater tendency that the precursor layer cannot be sufficiently fired.

Moreover, when the temperature of heat processing exceeds 600 degreeC, the tendency for the electrical resistance of the transparent electrode 1 to increase will become large. Further, in this case, the substrate 4 is distorted, and at least one of the following phenomena (i) to (iii) is generated, and the tendency of the battery performance to decrease is increased.
(I): a phenomenon in which a part or all of the precursor layer of the semiconductor electrode 2 (or the sintered semiconductor electrode 2) is peeled off,
(Ii): a phenomenon in which a part or all of the precursor layer (or the fired porous layer PS) of the porous layer PS is peeled off,
(Iii) Phenomenon in which part or all of the precursor layer (or counter electrode CE after firing) of the counter electrode CE is peeled off.

  In addition, the heat treatment here is performed in an oxidizing atmosphere and a non-oxidizing atmosphere (in an atmosphere not containing an oxidizing agent, for example, in an inert gas such as a rare gas or a chemically inert gas in the above temperature range such as nitrogen However, when the reaction is performed in an oxidizing atmosphere, it is preferably performed in a temperature range of 400 to 550 ° C. from the viewpoint of more reliably preventing the deterioration of the counter electrode CE (carbon electrode). However, even if the heat treatment for forming the counter electrode CE (carbon electrode) is omitted by firing the precursor layer of the counter electrode CE (carbon electrode), the precursor layer of the counter electrode CE (carbon electrode) is fired by the heat treatment described later. Thus, since the counter electrode CE (carbon electrode) can be formed, it is preferable to omit the heat treatment at this stage from the viewpoint of improving the production efficiency.

  Next, a treatment liquid containing a titanium compound is prepared, and a laminate composed of the transparent electrode 1, the semiconductor electrode 2, the porous body layer PS, and the counter electrode CE is immersed in the treatment liquid, and then the laminate is treated with the treatment. It is taken out from the liquid, washed, and heat-treated in an oxidizing atmosphere at a temperature range of 400 to 600 ° C. However, the heat treatment in an oxidizing atmosphere is preferably performed in a temperature range of 400 to 550 ° C. from the viewpoint of more reliably preventing the counter electrode CE from being deteriorated.

  The processing procedure and processing conditions in this step are the same as those of the solar cell 20 manufacturing method described above. That is, the titanium compound contained in the treatment liquid is preferably titanium trichloride, titanium alkoxide, or titanium complex. Further, titanium tetrachloride is also preferable as the titanium compound. Examples of the solvent or dispersion medium include water, alcohol, ethers, and ketones. In addition, at least two of these solvents or dispersion media may be arbitrarily mixed and used.

  Moreover, when the titanium compound contained in the processing liquid to be used is titanium trichloride, titanium alkoxide, or a titanium complex, it is preferable that the temperature at the time of immersing the laminated body obtained in a processing liquid is 0-50 degreeC.

  Furthermore, when the titanium compound contained in the processing liquid to be used is titanium tetrachloride, it is preferable that the temperature at the time of immersing the laminated body obtained in a processing liquid is 0-120 degreeC. Moreover, it is preferable that the density | concentration of the titanium compound in the processing liquid to be used is 0.01-0.20 mol / L.

  Furthermore, dilute hydrochloric acid aqueous solution, ethanol, or methanol is used as the cleaning liquid when the processed laminate is removed from the processing liquid containing the titanium compound and cleaned. The cleaning treatment is performed on the outer surface of the laminate [semiconductor electrode 2 (or precursor layer of semiconductor electrode 2), porous layer PS (or precursor layer of porous layer PS) and counter electrode CE (or counter electrode CE). This is a process for removing the excess treatment liquid adhering to the precursor layer (excluding the surface of the inner pore wall). However, in this cleaning process, the inside of the semiconductor electrode 2 (or the precursor layer of the semiconductor electrode 2), the porous body layer PS (or the precursor layer of the porous body layer PS) and the counter electrode CE (or the precursor layer of the counter electrode CE) The treatment liquid containing the titanium compound intruded into the pores is prevented from being removed outside the laminate.

  Next, a sensitizer is attached to the semiconductor electrode 2 by a known technique such as an immersion method (second step). Thus, the photoelectrode 10 is obtained. As described above, the sensitizer includes an organic dye. The method of attaching the sensitizer to the semiconductor electrode 2 is, for example, a method of immersing the obtained laminate (integrated photoelectrode 10, porous layer PS, and counter electrode CE) in a solution containing a dye. Can be used. At this time, adsorption and deposition of a sensitizer (for example, sensitizing dye) can be promoted by heating and refluxing the solution. At this time, in addition to the dye, a metal such as silver or a metal oxide such as alumina may be attached to the semiconductor electrode 2 as necessary.

  Next, a sealing material 5 having a shape matched to the size of the laminated body (one obtained by integrating the photoelectrode 10, the porous body layer PS, and the counter electrode CE) is prepared. As shown in FIG. The sealing material 5 is arranged on the side surface exposed to the outside of the body layer PS and the counter electrode CE3, and the outer surface of the bowl-shaped edge of the counter electrode CE, and heat-sealed.

  Next, on the back surface of the counter electrode CE (the outer surface of the counter electrode CE that is parallel to the back surface F22 of the semiconductor electrode 2 and is in contact with the porous layer PS), as shown in FIG. A moisture-proof film 7 is disposed on the substrate and heat-sealed.

  Next, the above-described electrolytic solution E is injected into the solar cell 30 (semiconductor electrode 2, porous body layer PS, and counter electrode CE). The injection of the electrolytic solution E can be performed, for example, using the photoelectrode 10, the counter electrode CE, or an injection port provided in advance in the sealing material 5. The injection port is closed by a predetermined member or resin after the injection of the electrolytic solution E is completed. In this way, the solar cell 30 is obtained.

(Third embodiment)
FIG. 3 is a cross-sectional view showing a dye-sensitized solar cell according to the third embodiment. In addition, the same code | symbol is attached | subjected to the component same as the solar cell of 1st and 2nd embodiment, and the overlapping description is abbreviate | omitted.

  As shown in FIG. 3, the solar cell 40 according to this embodiment has a form of a module in which a plurality of batteries are provided. Specifically, the solar cell 40 shown in FIG. 3 shows an example in the case where a plurality of the solar cells 30 shown in FIG. 2 are arranged in series (when three solar cells 30 are arranged in series).

  More specifically, the solar cell 40 shown in FIG. 3 has a plurality of the solar cells 30 shown in FIG. 2 arranged in parallel, and the transparent electrodes of the solar cells 30 are used as one common transparent electrode. Hereinafter, a portion of each solar cell 30 excluding the transparent electrode is referred to as a “single cell”.

  In the solar cell 40, the counter electrode CE of the central single cell among the three single cells is electrically connected to the semiconductor electrode 2 of the adjacent single cell through the transparent conductive film 3, and the semiconductor of the central single cell The electrode 2 is electrically connected to the counter electrode CE of the remaining single cell through the transparent conductive film 3. Accordingly, the three single cells are connected in series.

  In the present embodiment, the transparent electrode has a configuration in which the transparent conductive film 3 and the collecting electrode 6 are sequentially formed on the transparent substrate 4. Here, the current collecting electrode 6 has a lower resistance than the transparent conductive film 3 in order to further increase the photocurrent in the photoelectrode 10. As such a collector electrode 6, for example, a metal such as silver (Ag) or titanium (Ti) is used. Moreover, the shape of the current collection electrode 6 is not specifically limited, For example, it is mesh shape.

  Adjacent single cell sealing materials 5 are integrated to fill a gap between adjacent single cells, and also cover the counter electrodes CE of all single cells. Therefore, the sealing material 5 is also provided between the counter electrode CE and the moisture-proof film 7 in each single cell.

  Next, the manufacturing method of the solar cell 40 is demonstrated.

  First, the transparent electrode 11 is prepared. That is, a transparent substrate 4 in which a transparent conductive film 3 and a collecting electrode 6 are sequentially formed is prepared. Next, the same number of grooves 9 as the number of single cells are formed in parallel with each other at a predetermined interval by a laser scribing method or the like.

  Next, the above-described titanium oxide particle-containing composition is applied on the surface of the transparent electrode 11 on the current collecting electrode 6 side so as to avoid each groove 9 by screen printing. The titanium oxide particle-containing composition preferably contains a viscosity modifier. By including the viscosity modifier, the shape of the titanium oxide particle-containing composition after printing is maintained and fluidization is prevented, so that coalescence between adjacent titanium oxide particle-containing compositions is sufficiently prevented. . As a result, the solar cell 40 in which short-circuiting between single cells is sufficiently prevented is obtained.

  Next, the porous body layer PS and the counter electrode CE are formed. Attachment of the sensitizer to the semiconductor electrode 2 is the same as in the case of the first embodiment. Next, the sealing material 5 is arrange | positioned so that all the single cells (three in this embodiment) may be covered, and it heat-welds. Finally, the moisture-proof film 7 is stuck on the sealing material 5 to complete the production of the solar cell 40. In addition, about the formation method of porous body layer PS, counter electrode CE, and the sealing material 5, it is the same as the formation method of porous body layer PS, counter electrode CE, and the sealing material 5 in 2nd Embodiment.

  The present invention is not limited to the above embodiment. For example, in the above embodiment, the titanium oxide particle-containing composition is applied on the transparent electrode 1 and then baked to form the semiconductor electrode 2. However, instead of baking the titanium oxide particle-containing composition, ultraviolet irradiation is performed. Also, the semiconductor electrode 2 can be formed. That is, the semiconductor electrode 2 capable of increasing the photocurrent can be obtained by irradiating with ultraviolet rays without firing the titanium oxide particle-containing composition. The present inventors believe that this is due to the fact that the photocatalytic effect of titanium oxide is exhibited by ultraviolet irradiation, and the organic component serving as the resistance component is decomposed. In addition, the method of obtaining the photoelectrode by forming the semiconductor electrode 2 by irradiating with ultraviolet rays instead of firing as described above is particularly effective when the transparent electrode 1 is a low heat-resistant material such as a polymer film. is there.

  After the ultraviolet irradiation, the titanium oxide particle-containing composition is preferably heat-treated. In this case, the surface of the titanium oxide particles once reduced by ultraviolet irradiation is oxidized, the crystallinity of the oxidized semiconductor electrode 2 is improved, and the electron conductivity in the semiconductor electrode 2 is more than that in the case where heat treatment is not performed. improves.

  Moreover, although the said 1st Embodiment demonstrated the solar cell 20 provided with the electrode which has the structure similar to the transparent electrode 1 as a counter electrode CE, this counter electrode CE is a counter electrode CE which comprises the solar cell 30, ie, a carbon electrode. It is good. The counter electrode CE (carbon electrode) in this case can be produced by the same method as described above.

  In this case, a liquid containing a conductive carbon material is prepared, and the liquid is applied on a substrate and then dried to form a precursor layer of a counter electrode CE (carbon electrode). A porous counter electrode CE (carbon electrode) having pores may be formed by heat treatment in a temperature range of ° C. The heat treatment here is performed in an oxidizing atmosphere and a non-oxidizing atmosphere (in an atmosphere containing no oxidizing agent, for example, an inert gas such as a rare gas or a gas that is chemically inert in the above temperature range such as nitrogen. However, when the reaction is performed in an oxidizing atmosphere, it is preferably performed in a temperature range of 400 to 550 ° C. from the viewpoint of more reliably preventing the deterioration of the carbon electrode.

  Furthermore, in the said 3rd Embodiment, although the solar cell 30 was arranged in parallel and the solar cell which used the transparent electrode of each solar cell 30 as one common transparent electrode is shown, the solar cell of this invention May be a solar cell in which a plurality of solar cells 20 are arranged in parallel as a single cell, and the transparent electrode of each single cell is used as one common transparent electrode 1. In this case, the solar cell is obtained by connecting single cells in parallel.

  As described above, a dye-sensitized solar cell having high photocurrent and photoelectric conversion efficiency and improved durability and heat resistance can be provided.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples of the present invention. However, the present invention is not limited to these examples, and various modifications can be made without departing from the technical idea of the present invention. Can be changed.

(Preparation of dye-sensitized solar cell)
On a glass substrate with a transparent conductive film (TCO), a titanium oxide paste comprising titanium oxide (anaters type) nanoparticles (average particle size 20 nm), an organic dispersant, an organic thickener, and terpineol (solvent). After applying and drying by a screen printing method, baking was performed at 450 to 550 ° C. Further, a titanium oxide layer functioning as a reflective layer was laminated using a titanium oxide paste made of coarse particles of titanium oxide (average particle size: 200 to 400 nm), followed by heating and firing. The TCO substrate with the titanium oxide film was immersed in a typical red dye (N719) dye solution to adsorb the dye on the titanium oxide nanoparticles to produce a photoelectrode.

  Next, after applying an alcohol solution of chloroplatinic acid on a TCO glass substrate provided with micropores for injecting an electrolytic solution as a counter electrode, baking is performed at 350 to 450 ° C., whereby transparent nanoparticles having platinum nanoparticles are obtained. A counter electrode was produced.

  Provide a seal film (polyolefin-based thermoplastic resin film) that functions as a spacer that keeps the electrode interval opposite to the above-mentioned photoelectrode and the electrode gap, and also has a function of sealing the electrolyte solution. Then, the photoelectrode and the counter electrode were joined to each other through a seal film.

  Subsequently, after injecting the electrolytic solution from the microhole on the counter electrode side, a sealing film and a glass thin plate were provided on the upper portion of the hole, and the sealing film was heated and fused to enclose the electrolytic solution.

  The following was used for the electrolytic solution. A homogeneous mixture of iodine, PMII as an iodine compound which is an ionic liquid containing iodine ions, an imidazolium salt having a viscosity of 13 mPa · s, and purified N-methyl-benzimidazole as a benzimidazole derivative The electrolyte solution of Comparative Example 1 was prepared. Further, in the electrolyte solution of Comparative Example 1, dimethylmalononitrile (Example 1), adiponitrile (Example 2), tetraethylene glycol dimethyl ether (Example 3) as nonionic organic compounds that reduce the viscosity of the electrolyte solution. , Triethylene glycol dimethyl ether (Example 4), dimethyl phthalate (Example 5), and diethyl phthalate (Example 6) were further added to obtain electrolyte solutions of Examples 1 to 6, respectively. The amount of these organic compounds added was 20 to 50 wt% based on the entire electrolytic solution.

(Measurement of electrolyte viscosity)
The viscosity of the electrolyte solutions of Examples 1 to 6 and Comparative Example 1 was measured after the electrolyte solution was dropped on the sensor part of a digital ultrasonic viscometer (manufactured by Viscotec Co., Ltd.) and allowed to stand for several minutes. . The measurement was performed at room temperature. As a result, the viscosity of the electrolytic solution of Comparative Example 1 was 13 mPa · s. Moreover, the viscosity of the electrolyte solution of Examples 1-6 was 0.6, 0.5, 1.7, 0.4, 1.3, and 0.7 mPa * s, respectively.

(Measurement of photoelectric conversion efficiency)
Examples 1-6 and comparative examples using an AM1.5G solar simulator (WXS-85-H, manufactured by Wacom Denso) and an IV tester (IV-9701, manufactured by Wacom Denso) equipped with a 500 W xenon lamp The current (I) -voltage (V) characteristics (IV characteristics) of the dye-sensitized solar cell produced using the electrolytic solution 1 were measured, and the photoelectric conversion efficiency was measured. FIG. 4 is a graph plotting the photoelectric conversion efficiency of a dye-sensitized solar cell using this electrolytic solution against the viscosity of each electrolytic solution. From this result, it is shown that the electrolyte solutions of Examples 1 to 6 have lower viscosity than the electrolyte solution of Comparative Example 1, and the photoelectric conversion efficiency of the dye-sensitized solar cell using them is improved. It was.

(Photocurrent measurement)
AM1.5G solar simulator (WXS-85-H, manufactured by Wacom Denso Co., Ltd.) and IV, in which a 500 W xenon lamp is mounted on a dye-sensitized solar cell manufactured using the electrolyte solutions of Examples 1 to 6 and Comparative Example 1. Using a tester (IV-9701, manufactured by Wacom Denso), IV characteristics were measured, and photocurrent (short-circuit photocurrent) was measured. FIG. 5 is a graph plotting the photocurrent of a dye-sensitized solar cell using this electrolyte against the viscosity of each electrolyte. From these results, it was shown that the electrolyte solutions of Examples 1 to 6 had a lower viscosity than the electrolyte solution of Comparative Example 1, and increased the photocurrent of the dye-sensitized solar cell using them. .

(Photovoltaic voltage measurement)
AM1.5G solar simulator (WXS-85-H, manufactured by Wacom Denso Co., Ltd.) and IV, in which a 500 W xenon lamp is mounted on a dye-sensitized solar cell manufactured using the electrolyte solutions of Examples 1 to 6 and Comparative Example 1. Using a tester (IV-9701, manufactured by Wacom Denso), the IV characteristics were measured, and the photovoltage at the open end was measured. FIG. 6 is a graph plotting the photovoltage at the open end of a dye-sensitized solar cell using this electrolyte against the viscosity of each electrolyte. As a result, a good photovoltaic voltage was shown in any dye-sensitized solar cell using any electrolytic solution.

(Investigation of relationship between photocurrent and photoelectric conversion efficiency and viscosity)
An electrolytic solution in which iodine, PMII, and N-methyl-benzimidazole were homogeneously mixed was prepared. Hereinafter, this electrolytic solution is referred to as a Group I electrolytic solution. Moreover, the electrolyte solution which added further the imidazolium salt of the viscosity 12.7, 24.1, 13.3, 25.1, 8.0 mPa * s to this electrolyte solution was produced. Hereinafter, these electrolytic solutions are referred to as Group II electrolytic solutions. Furthermore, an electrolytic solution in which 30 to 50 wt% of adiponitrile or tetraethylene glycol dimethyl ether was added to the electrolytic solution of Comparative Example 1 based on the entire electrolytic solution was produced. Hereinafter, these electrolytic solutions are referred to as Group III electrolytic solutions.

  Photocurrents and photoelectric conversion efficiencies of dye-sensitized solar cells prepared using Group I to III electrolytes were measured in the same manner as described above. FIG. 7 is a graph plotting photocurrent and photoelectric conversion efficiency against the viscosity of each electrolyte solution. As a result, the group I electrolyte was plotted in the region I in FIG. Moreover, the electrolyte solution of group II was plotted in the area | region II part in FIG. The group III electrolytes were plotted in the region III in FIG. From the above results, it became clear that the photocurrent and the photoelectric conversion efficiency greatly depend on the viscosity of the electrolytic solution. Therefore, it is thought that lowering the viscosity of the electrolytic solution plays an important role in improving the performance of the dye-sensitized solar cell using the electrolytic solution.

(AC impedance measurement)
An electrolytic solution in which iodine, PMII, and N-methyl-benzimidazole were homogeneously mixed was prepared and used as the electrolytic solution of Comparative Example 2. Further, an electrolytic solution in which an imidazolium salt having a viscosity of 13 mPa · s was further added to the electrolytic solution of Comparative Example 2 was produced, and used as the electrolytic solution of Comparative Example 3. Furthermore, an electrolytic solution obtained by adding 40 wt% of triethylene glycol dimethyl ether to the electrolytic solution of Comparative Example 3 on the basis of the entire electrolytic solution was produced, and the electrolytic solution of Example 7 was obtained.

  Using a frequency analyzer (5080, manufactured by NF ELECTRONIC INSTRUMENTS) and a potentiostat (HZ-3000, manufactured by Hokuto Denko), a dye-sensitized solar using the electrolyte solutions of Example 7, Comparative Example 2 and Comparative Example 3 We measured the AC impedance of the battery. At that time, under white light irradiation from a xenon lamp, the frequency response in the frequency band of 10 mHz-100 kHz of impedance was measured near the open-circuit voltage.

  FIG. 8 is a graph showing the results of AC impedance measurement of dye-sensitized solar cells using the electrolyte solutions of Example 7, Comparative Example 2 and Comparative Example 3. It was revealed that the arc of impedance increased in the order of the dye-sensitized solar cells using the electrolyte solutions of Example 7, Comparative Example 3, and Comparative Example 2. The smaller the arc of impedance, the smaller the internal resistance, especially the interfacial resistance component between the photoelectrode and the electrolyte, indicating that the photocurrent and photoelectric conversion efficiency of the dye-sensitized solar cell are high.

(Accelerated endurance test)
The dye-sensitized solar cell produced using the electrolytic solution of Example 2 and the electrolytic solution of Comparative Example 1 was irradiated with continuous light (1 sun) from a xenon lamp at a constant temperature of 60 ° C., and an accelerated durability test was performed. . Before and after the accelerated durability test, using an AM1.5G solar simulator (WXS-85-H, manufactured by Wacom Denso) and IV tester (IV-9701, manufactured by Wacom Denso) equipped with a 500 W xenon lamp, The IV characteristics of the dye-sensitized solar cell were measured to determine the photoelectric conversion efficiency.

  FIG. 9 is a graph showing the transition of photoelectric conversion efficiency when a dye-sensitized solar cell produced using the electrolyte solutions of Examples and Comparative Examples is subjected to an accelerated durability test at 60 ° C. and 1 sun continuous light irradiation. It is. In FIG. 9, the vertical axis indicates the photoelectric conversion efficiency in arbitrary units, and the horizontal axis indicates the elapsed time in the durability test. As a result, compared to the electrolyte solution of Comparative Example 1, the dye-sensitized solar cell using the electrolyte solution of Example 2 showed higher photoelectric conversion efficiency. All the dye-sensitized solar cells showed good durability.

(Accelerated endurance test)
The electrolytic solution of Comparative Example 4 was prepared by adding 40 wt% of γ-butyrolactone having a boiling point of 204 ° C. under atmospheric pressure to the electrolytic solution of Comparative Example 1 based on the entire electrolytic solution. Subsequently, an accelerated endurance test in which the dye-sensitized solar cell produced using the electrolytic solution of Example 6, the electrolytic solution of Comparative Example 1 and the electrolytic solution of Comparative Example 4 is left in a dark place at a constant temperature of 85 ° C. went. Before and after the accelerated durability test, using an AM1.5G solar simulator (WXS-85-H, manufactured by Wacom Denso) and IV tester (IV-9701, manufactured by Wacom Denso) equipped with a 500 W xenon lamp, The IV characteristics of the dye-sensitized solar cell were measured to determine the photoelectric conversion efficiency.

  FIG. 10 is a graph showing the transition of photoelectric conversion efficiency when a dye-sensitized solar cell produced using the electrolytes of Examples and Comparative Examples is subjected to an accelerated durability test at 85 ° C. under dark conditions. is there. In FIG. 10, the vertical axis indicates the photoelectric conversion efficiency when the photoelectric conversion efficiency at the start of the test is 100%, and the horizontal axis indicates the elapsed time in the durability test. As a result, the dye-sensitized solar cell produced with the electrolytic solution of Comparative Example 4 has a lower photoelectric conversion efficiency in a shorter time than the dye-sensitized solar cell produced with the electrolytic solution of Comparative Example 1, and durability and It was shown to be inferior in heat resistance. In contrast, the dye-sensitized solar cell using the electrolytic solution of Example 6 has improved durability and heat resistance compared to the dye-sensitized solar cell using the electrolytic solution of Comparative Example 1 or Comparative Example 4. Indicated.

It is sectional drawing which shows the dye-sensitized solar cell which concerns on 1st Embodiment. It is sectional drawing which shows the dye-sensitized solar cell which concerns on 2nd Embodiment. It is sectional drawing which shows the dye-sensitized solar cell which concerns on 3rd Embodiment. It is the graph which plotted the photoelectric conversion efficiency of the dye-sensitized solar cell using this electrolyte solution with respect to the viscosity of the electrolyte solution of an Example and a comparative example. It is the graph which plotted the photocurrent of the dye-sensitized solar cell using this electrolyte solution with respect to the viscosity of the electrolyte solution of an Example and a comparative example. It is the graph which plotted the photovoltaic voltage of the dye-sensitized solar cell using this electrolyte solution with respect to the viscosity of the electrolyte solution of an Example and a comparative example. It is the graph which plotted the photocurrent and photoelectric conversion efficiency of the dye-sensitized solar cell using this electrolyte solution with respect to the viscosity of the electrolyte solution of an Example and a comparative example. It is a graph which shows the result of having performed alternating current impedance measurement. It is the graph which showed transition of photoelectric conversion efficiency. It is the graph which showed transition of photoelectric conversion efficiency.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Transparent electrode (transparent conductive substrate), 2 ... Semiconductor electrode, 3 ... Transparent electrically conductive film, 4 ... Transparent substrate, 5 ... Sealing material, 6 ... Current collecting electrode, 7 ... Moisture-proof film, 9 ... Formed by laser scribing Groove, 10 ... Photoelectrode, 20, 30, 40 ... Dye-sensitized solar cell, CE ... Counter electrode, F1, F2, F3 ... Light receiving surface, F22 ... Back surface of semiconductor electrode 2, PS ... Porous layer, E ... Electrolytic solution.

Claims (7)

In an electrolytic solution containing iodine and an iodine compound that is an ionic liquid containing iodine ions,
Further containing a nonionic organic compound that lowers the viscosity of the electrolyte ,
In addition to the iodine compound, it further contains an ionic liquid having a viscosity of 5 to 30 mPa · s, and the ionic liquid is ethylmethylimidazolium bis (fluorosulfonyl) imide, allylmethylimidazolium bis (trifluoromethanesulfonyl) imide. Alternatively , an electrolyte solution that is ethylmethylimidazolium tetracyanoborate . The electrolyte solution according to claim 1 , wherein the organic compound has a boiling point of 220 ° C. or higher under atmospheric pressure. The electrolyte solution according to claim 1 or 2 , wherein the organic compound is at least one compound selected from the group consisting of a bifunctional nitrile compound, a polyethylene glycol dialkyl ether, and a phthalate ester. The electrolytic solution according to claim 3, wherein the organic compound is a phthalate ester.   The electrolysis according to any one of claims 1 to 4, further comprising a benzimidazole derivative having a benzimidazole ring and a saturated hydrocarbon group which may be directly bonded to the benzimidazole ring. liquid.   The electrolyte solution according to any one of claims 1 to 5, further comprising a guanidine salt.   A dye-sensitized solar cell comprising the electrolytic solution according to any one of claims 1 to 6.

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