JP2011070876A - Dye-sensitized photoelectric conversion element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a dye-sensitized photoelectric conversion element with improved efficiency of photoelectric conversion, in one made up by arranging a working electrode with conductivity and a counter electrode through electrolyte. <P>SOLUTION: Of the dye-sensitized photoelectric conversion element 1 made up by arranging a working electrode 5 with conductivity and a counter electrode 6 through electrolyte 18, the working electrode 5 and the counter electrode 6 are insulated from each other by particles 28 made of an insulator contained in the electrolyte 18, with a shape of the particles made of the insulator of a spherical shape with a maximum outer diameter of 40 μm or more and 120 μm or less. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a dye-sensitized photoelectric conversion element used for solar cells and the like. More specifically, the present invention relates to a dye-sensitized photoelectric conversion element with improved photoelectric conversion efficiency.

The dye-sensitized solar cell has been proposed by a group such as Gretzel et al. In Switzerland, and has attracted attention as a photoelectric conversion element that can obtain high conversion efficiency (see, for example, Non-Patent Document 1).
Dye-sensitized solar cells can be significantly reduced in price compared to silicon-based conventional solar cells, but the price of conductive substrates used in power generation units is an obstacle to lower prices It has become. In a dye-sensitized solar cell having a conventional structure, the electrode (window electrode) on which light enters is particularly required to have visible light transmission and high conductivity. A substrate coated with a transparent conductive metal oxide such as indium oxide or fluorine-doped tin oxide has been used. Therefore, if a dye-sensitized solar cell having a completely new structure that does not use such a transparent conductive substrate is realized, research and development are being carried out on the assumption that the cost of solar cells can be greatly reduced. .

As a solution to these problems, a novel element structure (see Patent Documents 1, 2, 3, and 4) using a metal wire as a working electrode of a power generation unit has been proposed. However, in these structures, since a metal wire is used for the working electrode, it is difficult to configure a large-area solar cell module, and it is easy to increase the area that a dye-sensitized photoelectric conversion element originally has. As a result, the advantage was lost. Therefore, it is necessary to develop an element structure that does not impair the above advantages.
Furthermore, as described in Patent Document 5 and Patent Document 6, a structure in which metal wires are knitted in a mesh shape has been proposed as a structure that enables a large-area element.

JP 2008-181690 A JP 2008-181691 A JP 2005-196982 A JP 2005-516370 gazette JP 2001-283941 A JP 2001-283944 A

O'Regan B., Graetzel M., Alow cost, high-efficiency solar cell based on dye-sensitized colloidal TiO2 films, Nature, 1991, 353, 737-739

  By the way, in the case of the dye-sensitized solar cell 100 using the conventional fine metal wires as shown in FIG. 6, it is composed of a mesh electrode made of the fine metal wires and a porous oxide semiconductor layer 113 on which the dye is supported. The working electrode 105 and the counter electrode 106 made of a conductive substrate are electrically insulated by a separator 110 usually made of an insulating material. In the conventional separator 110, a porous porous membrane (porous sheet) made of resin is inserted between the working electrode 105 and the counter electrode 106, and an electrolyte 118 including a redox pair etc. diffuses and permeates the porous flat membrane. Electrons are supplied from the counter electrode 106 to the dye supported on the porous oxide semiconductor layer 113. However, since the efficiency of the redox couple passing through the porous flat membrane is low, there is a problem that the efficiency of supplying electrons to the dye is poor and the photoelectric conversion efficiency of the dye-sensitized solar cell 100 remains low. Further, at the location where the porous flat membrane and the counter electrode are in close contact, the efficiency of electron supply from the counter electrode to the oxidized component of the redox pair is poor, and the effective area of the counter electrode is reduced. There was a problem that the photoelectric conversion efficiency of the battery 100 remained low.

  The present invention has been made in view of the above circumstances, and is a dye-sensitized photoelectric conversion element in which a conductive working electrode and a counter electrode are arranged via an electrolyte, and the photoelectric conversion efficiency is improved. It is an object to provide a dye-sensitized photoelectric conversion element.

The dye-sensitized photoelectric conversion element according to claim 1 of the present invention is a dye-sensitized photoelectric conversion element in which a working electrode having conductivity and a counter electrode are arranged via an electrolyte, The electrode and the counter electrode are insulated by particles made of an insulator contained in the electrolyte, and the particles made of the insulator have a spherical shape with a maximum outer diameter of 40 μm to 120 μm.
A dye-sensitized photoelectric conversion element according to a second aspect of the present invention is the dye-sensitized photoelectric conversion element according to the first aspect, wherein the working electrode has a plurality of first and second base materials that are conductive and linear. It is characterized by comprising a region knitted into a shape.
The dye-sensitized photoelectric conversion element according to claim 3 of the present invention is the dye-sensitized photoelectric conversion element according to claim 1 or 2, wherein the particles made of the insulator are spherical glass particles, and 1.0 mass in the electrolyte. % To 5.0% by mass or less.

According to the dye-sensitized photoelectric conversion element of the present invention, by using particles made of an insulator contained in the electrolyte in order to electrically insulate the working electrode and the counter electrode, Since the electron transfer efficiency can be increased, the photoelectric conversion efficiency can be improved.
That is, by using the particles made of the insulator as a separator, the diffusion and permeation of the electrolyte occurs more quickly than in the case of a separator made of a conventional porous flat membrane, so that the working electrode is changed from the counter electrode performed by the electrolyte. Therefore, the dye-sensitized photoelectric conversion element of the present invention is more excellent in photoelectric conversion efficiency than the conventional one.
Further, the particles made of the insulator are particles made of a spherical insulator having a maximum outer diameter of 40 μm or more and 120 μm or less, whereby a plurality of the insulators interposed between the working electrode and the counter electrode A gap having a sufficient distance can be formed between the working electrode and the counter electrode, and the working electrode and the counter electrode can be sufficiently insulated.
Further, since the particles made of the insulator are spherical, the area where the working electrode and the counter electrode are in close contact with the particles made of the insulator is small, and the effective area of each of the working electrode and the counter electrode is small. You can insulate them without. In addition, since the particles made of the insulator are spherical, it is easy to disperse the particles made of the insulator in the electrolyte, and damage due to contact between the particles made of the insulator hardly occurs. Is also easier.

In the dye-sensitized photoelectric conversion element of the present invention, the working electrode is composed of a region in which a plurality of first and second base materials that are conductive and have a linear shape are knitted in a mesh shape. It is preferable that the dye-sensitized photoelectric conversion element of the present invention is excellent in flexibility and photoelectric conversion efficiency is improved.
In the dye-sensitized photoelectric conversion device of the present invention, the particles made of the insulator are spherical glass particles, and the electrolyte has a ratio of 1.0% by mass to 5.0% by mass. When it is included, it is preferable because the particles made of the insulator interposed between the working electrode and the counter electrode can perform efficient photoelectric conversion while sufficiently forming the gap.

1 is a schematic configuration diagram of a dye-sensitized photoelectric conversion element as a first embodiment according to the present invention. It is a schematic sectional drawing in alignment with the A-A 'line in the schematic block diagram (FIG. 1) which shows 1st Embodiment based on this invention. BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic sectional drawing of the current collection part 3 in alignment with the BB 'line | wire in the schematic block diagram (FIG. 1) which shows 1st Embodiment based on this invention, (a) is before resistance welding, (b) is (C) is sectional drawing after resistance welding during resistance welding. It is a schematic block diagram of a dye-sensitized photoelectric conversion element as 2nd Embodiment which concerns on this invention. It is a schematic sectional drawing which follows the C-C 'line in the schematic block diagram (FIG. 4) which shows 2nd Embodiment based on this invention. It is a schematic sectional drawing of an example of the conventional dye-sensitized photoelectric conversion element.

<First embodiment>
Hereinafter, an example of the dye-sensitized photoelectric conversion element according to the present invention will be described in detail with reference to the drawings.

As shown in FIGS. 1 and 2, the dye-sensitized photoelectric conversion element 1 </ b> A (1) according to the first embodiment of the present invention is a power generation unit 2 having a rectangular shape in plan view and a collection provided outside the power generation unit 2. The power generation unit 2 is configured such that electrons generated in the power generation unit 2 are collected in the current collection unit 3 via a current collection wiring 4 extending from one side of the power generation unit 2.
The power generation unit 2 includes a working electrode 5 having a mesh structure knitted into a mesh having a rectangular shape in plan view and a plate-like counter electrode 6 having a rectangular shape in plan view through particles 28 made of an insulator contained in an electrolyte 18. Are configured to overlap each other. The working electrode 5 having a network structure is arranged around the plurality of first base materials 8 and the plurality of second base materials 9 having conductivity, and around the first base material 8 and the second base material 9. It is comprised from the porous oxide semiconductor layer 13 which carry | supported the sensitizing dye, This porous oxide semiconductor layer 13 is also impregnating the electrolyte 18 with the sensitizing dye.
The first base material 8 and the second base material 9 are both linear, and the first base material 8 and the second base material 9 are knitted in a mesh shape to form a region having a rectangular mesh structure. There is no.

The counter electrode 6 is a plate-like conductive base material, and is overlapped with the working electrode 5 via particles 28 made of an insulator contained in the electrolyte 18. The counter electrode 6 has an extraction electrode 6 a that is paired with the current collector 3, and the extraction electrode 6 a extends to the outside of the power generation unit 2.
The electrolyte 18 including the working electrode 5, the counter electrode 6, and the particles 28 made of an insulator interposed therebetween is stored in the storage bag 14, and the storage bag 14 is filled with the electrolyte 18.

  The particles 28 made of an insulator are interposed between the working electrode 5 and the counter electrode 6 together with the electrolyte 18 and function as a separator that electrically insulates the working electrode 5 and the counter electrode 6. At this time, the particles 28 made of the insulator are contained in the electrolyte 18. Of the redox couple contained in the electrolyte 18, the oxidized component obtains an electron from the counter electrode 6 to become a reduced component, diffuses and moves from the counter electrode 6 to the working electrode 5, and passes the electrons to the working electrode to give the oxidized component. Then, it again moves to the counter electrode 6 by diffusion movement. In this way, the redox pair plays a role of transferring electrons from the counter electrode 6 to the working electrode 5.

In the conventional dye-sensitized photoelectric conversion element 100 (FIG. 6) using a porous flat membrane as the separator 110, when the oxidation-reduction pair diffuses and moves between the counter electrode 6 and the working electrode 5, the porous Although it is necessary to permeate through the flat membrane, the efficiency of the diffusion movement is not necessarily good.
On the other hand, since the particles 28 made of an insulator are used as a separator in the present invention, the redox couple only needs to pass through the side of the particles 28 made of an insulator, and the efficiency of diffusion transfer is excellent. The photoelectric conversion efficiency of the dye-sensitized photoelectric conversion element 1 of the invention is improved.

All of the plurality of first base materials 8 constituting the working electrode 5 are extended outward from the working electrode 5 to become the current collecting wiring 4 and constitute a current collecting region 19 outside.
The current collecting area 19 is composed of a first base material 8 constituting the current collecting wiring 4 and a plurality of outer peripheral base materials 20 having conductivity. The outer peripheral base material 20 has a linear shape, and constitutes a part formed by meshing with the current collector wiring 4.

  A Cu foil 21 is overlaid on the current collecting region 19, and the current collecting region 19 and the Cu foil 21 are sandwiched between two Ti foils 22a and 22b. The current collecting region 19, the Cu foil 21, and the Ti foils 22 a and 22 b are pressure-bonded by a resistance welding method and integrated in a plurality of spot welds 24. A part of the Cu foil 21 is drawn to the outside, and current can be collected from this part.

Hereinafter, each component will be described in detail.
In the dye-sensitized photoelectric conversion element 1A (1) of the first embodiment illustrated in FIGS. 1 and 2, the first base material 8, the second base material 9, and the outer peripheral base material 20 are copper having a diameter of 0.05 mm. It is a metal wire (hereinafter referred to as Ti-coated Cu wire) in which a (Cu) wire is coated with titanium (Ti).
The Ti-coated Cu wire can be produced by a known method. For example, Ti is formed into a pipe shape by extrusion molding or the like, and Cu is formed into a linear shape by extrusion molding or the like, and the Cu wire is inserted into the Ti pipe while running these Ti pipe and Cu wire simultaneously, By squeezing them and bringing them into close contact, a Ti-coated Cu wire can be obtained.
A Ti-coated Cu wire produced by such a wire drawing method has better adhesion of the coating layer than that produced by a sputtering method, a plating method or the like, and the production cost can be kept low.

The working electrode 5 has a structure in which a predetermined number of the first base material 8 and the second base material 9 are knitted in a mesh shape. The 1st base material 8 and the 2nd base material 9 are knitted so that it may mutually contact in an overlapping part, and have the mesh-like structure which makes a rectangle.
The gap area (aperture ratio) per unit area of the network structure is not particularly limited, and may be, for example, 0% or more and 20% or less. However, in order to form a sufficient gap between the working electrode 5 and the counter electrode 6, the size of the opening is preferably such that the particles 28 made of the insulator cannot pass through.

The 1st base material 8, the 2nd base material 9, and the outer periphery base material 20 are not restricted to Ti covering Cu wire, The wire which has corrosivity with respect to electrolyte solution, such as tungsten (W) covering Cu wire, can also be used. is there. A highly conductive wire such as a Ti-coated aluminum (Al) wire can also be used.
The thickness (diameter) of such a substrate is preferably 10 μm to 10 mm, for example.
However, in order to fully exhibit flexibility, the thinner the substrate, the better.

In the power generation unit 2 shown in FIG. 1, of the surrounding four sides, the sides located on the sides are the first side 30 and the second side 31, respectively, and the sides located above and below are the third side 32 and the fourth side, respectively. 33, each second base material 9 extends from the third side 32 to the fourth side 33, and a plurality of second base materials 9 are provided from the first side 30 to the second side 31. There are several lines.
The plurality of first base materials 8 are arranged in a predetermined number from the third side 32 to the fourth side 33 and extend from the first side 30 to the current collector 3. That is, all of the first base materials 8 among the base materials constituting the working electrode 5 are drawn out so as to be extended from the power generation section 2 from one side of the power generation section 2 having a rectangular shape.

The extended first base material 8 is knitted in a mesh shape so as to intersect with the outer peripheral base material 20 at a predetermined position, thereby forming a network structure. It is preferable that the outer peripheral base material 20 is composed of three or more so that a network structure can be formed.
Of the first base material 8, the portion between the second side 31 and the current collector 3 serves as the current collector wiring 4, and the electrons generated at the working electrode 5 pass through the current collector wiring 4. Collected in the current collector 3.

The weaving method of the region knitted in a mesh shape is not limited to the plain weave illustrated in FIG. 1, and a method similar to a general cloth weaving method such as twill weave or satin weave can be applied. In the plain weaving, a plurality of vertical lines made of the second base material 9 are alternately divided one above the other on the loom, and the first base material 8 is made between the plurality of vertical lines divided up and down. The process in which the weft is passed and driven with a scissors is one cycle. In the next cycle, the top and bottom of a plurality of vertical lines are replaced with the previous cycle, and the lines are alternately separated one by one again.
Thus, the working electrode 5 which consists of the area | region of the network structure formed by the 1st base material 8 and the 2nd base material 9 being knitted by mesh shape can be obtained.

Of the first base material 8 and the second base material 9, a portion of the working electrode 5 having a network structure is provided with a porous oxide semiconductor layer 13 on the surface thereof, and at least a part of the surface is provided on the surface. A sensitizing dye is supported on the surface. Of the first substrate 8, the porous oxide semiconductor layer 13 does not have to be disposed on the current collecting wiring 4.
Titanium oxide (TiO ₂ ) is used as the semiconductor that forms the porous oxide semiconductor layer 13. The film thickness of this titanium oxide is not specifically limited, For example, it can carry out at 1 micrometer-50 micrometers.
The semiconductor that forms the porous oxide semiconductor layer 13 is not limited to titanium oxide, and is generally zinc oxide (ZnO), tin oxide (SnO ₂ ), or the like as long as it is used in a dye-sensitized solar cell. Various semiconductor electrodes such as zinc oxide (ZnO), niobium oxide (Nb ₂ O ₅ ), and tungsten oxide (WO ₃ ) can be used without limitation.

  Examples of the sensitizing dye include ruthenium complexes such as N719, N3, and black dye, metal-containing complexes such as porphyrin and phthalocyanine, and organic dyes such as eosin, rhodamine, and merocyanine. From the above, it is only necessary to appropriately select one having an excitation behavior suitable for the application and the semiconductor used.

  The porous oxide semiconductor layer 13 is impregnated with an electrolytic solution, and this electrolytic solution also constitutes a part of the electrolyte 18. In this case, the electrolyte 18 in the porous oxide semiconductor layer 13 is formed by impregnating the porous oxide semiconductor layer 13 with an electrolytic solution, or impregnating the porous oxide semiconductor layer 13 with an electrolytic solution. Then, the electrolyte solution is gelled (pseudo-solidified) using an appropriate gelling agent and formed integrally with the porous oxide semiconductor layer 13 or based on an ionic liquid Further, a gel electrolyte containing oxide semiconductor particles or conductive particles is used. However, when the oxide semiconductor particles or the conductive particles are used, in order to sufficiently insulate between the working electrode 5 and the counter electrode 6, the maximum outer diameter of these particles is made of the insulator. It is preferably smaller than the maximum outer diameter of the particles 28.

  Part of the particles 28 made of an insulator contained in the electrolyte 18 may be contained in the porous oxide semiconductor layer 13, but usually the particles 28 made of an insulator having a porous pore size. Since it is smaller than that, it does not enter. In order for the insulating particles 28 to sufficiently insulate by forming a gap between the working electrode 5 and the counter electrode 6, the insulating particles 28 do not enter the porous oxide semiconductor layer 13. Is preferred.

  The shape of the particles 28 made of the insulator is a spherical shape having a maximum outer diameter of 40 μm or more and 120 μm or less. With this shape, the gap between the working electrode 5 and the counter electrode 6 formed by the particles 28 made of a plurality of insulators interposed between the working electrode 5 and the counter electrode 6 can be made substantially uniform. On the other hand, particles made of an insulator having an irregular shape can be used, but it becomes difficult to control the distance of the gap between the working electrode 5 and the counter electrode 6, resulting in poor insulation.

  Here, in the claims and specification of the present invention, the spherical shape means a substantially spherical shape in which the ratio of the major axis to the minor axis is 1.5 or less. The ratio of the major axis to the minor axis is preferably 1.2 or less, and most preferably 1.0. When the ratio of the major axis to the minor axis is 1.0, the substantially spherical shape is a true sphere. The major axis means the longest diameter in the outer diameter of the particles made of the insulator, and the minor diameter means the shortest diameter in the outer diameter of the particles made of the insulator. The diameter means a distance of a straight line passing through the center of gravity in the particle made of the insulator and connecting two points on the surface of the particle.

  Thus, since the particles 28 made of the insulator are spherical, the contact area between the working electrode 5 and the counter electrode 6 and the particles 28 made of the insulator is small, and the working electrode 5 and the counter electrode 6 are small. They can be insulated without reducing their effective area. Furthermore, it is easy to disperse in the electrolyte 18, damage due to contact between the particles 28 made of the insulator hardly occurs, and handling becomes easy.

The maximum outer diameter of the particles 28 made of the insulator is 40 μm or more and 120 μm or less, preferably 40 μm or more and 80 μm or less, and most preferably 40 μm or more and 60 μm or less.
When the value is equal to or greater than the lower limit of the above range, the distance between the working electrode 5 and the counter electrode 6 formed by the particles 28 made of a plurality of insulators interposed between the working electrode 5 and the counter electrode 6 is sufficiently secured. The working electrode 5 and the counter electrode 6 can be sufficiently insulated.
When the distance is not more than the upper limit of the above range, the distance between the working electrode 5 and the counter electrode 6 formed by the particles 28 made of a plurality of insulators interposed between the working electrode 5 and the counter electrode 6 is the above-mentioned electron. The distance can be moved more efficiently, and the photoelectric conversion efficiency can be improved.
On the other hand, if it is below the lower limit of the above range, the distance between the working electrode 5 and the counter electrode 6 becomes too short, and it becomes difficult to maintain the insulation between the working electrode 5 and the counter electrode 6. In this case, the working electrode 5 and the counter electrode 6 may be insulated by increasing the proportion of the particles 28 made of an insulator contained in the electrolyte 18. However, when the maximum outer diameter of the particles 28 made of the insulator is extremely small (for example, smaller than 1 μm), the working electrode 5 and the counter electrode 6 can be obtained even if the proportion contained in the electrolyte 18 is increased. It is extremely difficult to sufficiently insulate, and it is not practical to use such extremely small particles.

The material of the particles 28 made of the insulator is not particularly limited as long as it is a chemically stable insulating material having corrosion resistance with respect to the electrolyte 18. For example, zirconia, alumina, quartz glass, soda lime glass, organic glass Etc. Among these, soda-lime glass is preferable because it is easy to make it granular.
When the particles 28 made of the insulator are spherical glass particles having a maximum outer diameter of 40 μm or more and 120 μm or less using soda lime glass as a material, the particles 28 made of the insulator are 1 in the electrolyte 18. It is preferably contained in a proportion of not less than 5% by mass and not more than 5.5% by mass, more preferably in the electrolyte 18 in a proportion of not less than 2.0% by mass and not more than 5.0% by mass. It is preferably contained in a proportion of 2.5% by mass or more and 3.5% by mass or less.
Further, when the particles 28 made of the insulator are spherical glass particles having a maximum outer diameter of 60 μm or more and 120 μm or less using soda lime glass as a material, the particles 28 made of the insulator are contained in the electrolyte 18. Is preferably contained in a proportion of 0.8% by mass or more and 5.5% by mass or less, more preferably 0.9% by mass or more and 5.0% by mass or less in the electrolyte 18. It is preferably contained in a proportion of 1.0% by mass or more and 3.5% by mass or less.
When the ratio is not less than the lower limit of the above range, the particles 28 made of the insulator interposed between the working electrode 5 and the counter electrode 6 are electrically connected with the gap between the working electrode 5 and the counter electrode 6 maintained. Insulation can be performed more reliably.
When the ratio is not more than the upper limit of the above range, efficient photoelectric conversion can be performed while electrically insulating while maintaining a gap between the working electrode 5 and the counter electrode 6.

  The manufacturing method of the particle | grains 28 which consist of an insulator mentioned above can use a well-known method, and what used the said soda-lime glass as a material can use a commercial item.

As said electrolyte solution, what melt | dissolved electrolyte components, such as an iodine, iodide ion, and tertiary butyl pyridine, in organic solvents and ionic liquids, such as ethylene carbonate and methoxyacetonitrile, is used.
Examples of the gelling agent used for gelling the electrolytic solution include polyvinylidene fluoride, a polyethylene oxide derivative, and an amino acid derivative.
Moreover, if it replaces with a volatile electrolyte solution and is generally used for a dye-sensitized solar cell, not only what a solvent is an ionic liquid or the gelatinized thing but a p-type inorganic semiconductor and an organic hole transport layer Even solids such as these can be used without limitation.

Although it does not specifically limit as said ionic liquid, It is a liquid at room temperature, For example, the normal temperature molten salt which used the compound which has the quaternized nitrogen atom as a cation is mentioned.
Examples of the cation of the room temperature molten salt include quaternized imidazolium derivatives, quaternized pyridinium derivatives, and quaternized ammonium derivatives.
Examples of the anion of the room temperature molten salt include BF ₄ ⁻ , PF ₆ ⁻ , (HF) _n ⁻ , bistrifluoromethylsulfonylimide [N (CF ₃ SO ₂ ) ₂ ⁻ ], and iodide ions.
Specific examples of the ionic liquid include salts composed of quaternized imidazolium-based cations and iodide ions or bistrifluoromethylsulfonylimide ions.

  The oxide semiconductor particles are not particularly limited in terms of the type and particle size of the substance, but are excellent in miscibility with an electrolyte mainly composed of an ionic liquid and gel the electrolyte. Is used. However, the maximum outer diameter of the oxide semiconductor particles is preferably smaller than the maximum outer diameter of the particles 28 made of the insulator. In addition, the oxide semiconductor particles are required to have excellent chemical stability against other coexisting components contained in the electrolyte 18 without reducing the semiconductivity of the electrolyte 18. In particular, even when the electrolyte 18 includes a redox pair such as iodine / iodide ions or bromine / bromide ions, the oxide semiconductor particles are preferably those that do not deteriorate due to an oxidation reaction.

Examples of such oxide semiconductor particles include TiO ₂ , SnO ₂ , SiO ₂ , ZnO, Nb ₂ O ₅ , In ₂ O ₃ , ZrO ₂ , Al ₂ O ₃ , WO ₃ , SrTiO ₃ , Ta ₂ O ₅ , One or a mixture of two or more selected from the group consisting of La ₂ O ₃ , Y ₂ O ₃ , Ho ₂ O ₃ , Bi ₂ O ₃ , CeO ₂ is preferable, and the average particle size is about 2 nm to 1000 nm. preferable.

As the conductive particles, conductive particles such as conductors and semiconductors are used.
Further, the type and particle size of the conductive particles are not particularly limited, and those that are excellent in miscibility with an electrolytic solution mainly composed of an ionic liquid and that gel the electrolytic solution are used. However, the maximum outer diameter of the conductive particles is preferably smaller than the maximum outer diameter of the particles 28 made of the insulator. Furthermore, it is necessary to be excellent in chemical stability against other coexisting components contained in the electrolyte 18.
In particular, even when the electrolyte 18 contains an oxidation-reduction pair such as iodine / iodide ions or bromine / bromide ions, an electrolyte that does not deteriorate due to an oxidation reaction is preferable.

  Examples of such conductive fine particles include those composed mainly of carbon, and specific examples include particles such as carbon nanotubes, carbon fibers, and carbon black. All methods for producing these substances are known, and commercially available products can also be used.

  The counter electrode 6 has a plate shape having conductivity, and a Ti plate having a thickness of 0.1 mm whose surface is non-conductive is used. The counter electrode 6 has a catalyst film (not shown) made of Pt on the surface. Note that an extraction electrode 6a is provided at the end for current collection.

The electrolyte 18 including the working electrode 5, the counter electrode 6, and the particles 28 made of an insulator is stored in a storage bag 14 made of PET or PEN (polyethylene naphthalate). The material used for the storage bag 14 is not limited to PET and PEN, and can be appropriately changed as long as the material has translucency and can withstand the electrolytic solution.
An electrolyte 18 is sealed in the storage bag 14 and is sealed with an adhesive so that the current collection wiring 4 of the working electrode 5 and the extraction electrode 6a of the counter electrode 6 are exposed to the outside. As an adhesive material, an adhesive material that can withstand an electrolyte and can provide a good adhesive force with the storage bag 14 and Ti is preferable.

Next, the structure of the current collector 3 of the dye-sensitized photoelectric conversion element 1A (1) and the manufacturing method thereof according to the first embodiment of the present invention will be described with reference to FIG.
Similar to the power generation unit 2, the current collector 3 has a mesh electrode. In order to implement current collection, Cu foil 21 is used, and Cu foil 21 and current collection region 19 forming a mesh electrode are overlapped and integrated using resistance welding.

  However, when pressure bonding is performed directly between the Cu foil 21 and the current collecting region 19 that is a mesh electrode using a resistance welding method, Cu has a lower melting point than Ti, and therefore, prior to Ti during resistance welding. Will melt. In this case, since the molten Cu is deposited on the resistance welding electrode 25 used in the resistance welding method, the current collecting region 19 and Cu are not joined. Further, when resistance welding is performed by directly bringing the current collecting region 19 of the mesh electrode and the resistance welding electrode 25 into contact with each other, a difference occurs in the joining state depending on the contact state, so that welding is not stable.

  Therefore, in the first embodiment of the present invention, as shown in FIG. 3A, the current collection region 19 and the Cu foil 21 are overlapped, and the current collection region 19 and the Cu foil 21 are further combined. Resistance welding was performed while being sandwiched between a pair of Ti foils 22a and 22b. In FIG. 3B, the current collecting region 19, the Cu foil 21, and the pair of Ti foils 22 a and 22 b are pressed with a pair of resistance welding electrodes 25, and then a current is passed to perform resistance welding. It is a figure which shows a mode.

As a result, as shown in FIG. 3C, the melted portion 23 is formed by melting the inner current collecting region 19 and the Cu foil 21 during resistance welding, so that the Cu foil 21 and the current collecting region 19 are sufficiently formed. Could be joined. On the other hand, since the resistance welding electrode 25 is in contact with only the Ti foils 22a and 22b, Cu was not deposited on the resistance welding electrode 25.
After welding, current is collected from the portion of the Cu foil 21 having low contact resistance, so that current collection becomes easy.

  As described above, the current collecting region 19 and the Cu foil 21, the Ti foil 22a, and the Ti foil 22b can be welded by a method using seam welding or a laser welding method in addition to the method of performing spot welding at multiple points. . The current collecting region 19 and the Cu foil 21, the Ti foil 22a, and the Ti foil 22b are preferably welded as continuously as possible.

  In order to protect the current collector 3, the welded current collector 3 is preferably impregnated with resin. The resin is not particularly limited as long as it is chemically stable to the electrolytic solution and has good adhesion to the Ti foil 22a and the Ti foil 22b. For example, polyimide, fluorine-containing resin, PET resin, etc. Is mentioned. Further, instead of the resin, a low viscosity adhesive may be applied to the current collector 3.

In the dye-sensitized photoelectric conversion element 1A (1) of the first embodiment described above, the mesh-shaped current collecting region 19 and the Cu foil 21 constituting the current collecting unit 3 are pressure-bonded using a resistance welding method, and collected. By melting the electric current region 19 and the Cu foil 21, the contact resistance between the current collecting region 19 and the Cu foil 21 is greatly reduced, and the photoelectric conversion efficiency can be improved.
In addition, when an electrical device or the like is connected to the Cu foil 21 via a connection conductor, all of the electrons generated in the first base material 8 among the electrons generated in the power generation unit 2 when a light beam such as sunlight is incident. Therefore, the photoelectric conversion efficiency can be improved.
Further, the power generation unit 2 is a combination of the working electrode 5 having a mesh structure, the plate-like counter electrode 6, the particles 28 made of an insulator contained in the electrolyte 18, and the storage bag 14 made of PET, and thus has excellent flexibility. Thinning is also possible.
Further, when the working electrode 5 composed of the first base material 8 and the second base material 9 is knitted in a mesh shape so as to cross each other, the current collecting region 19 is knitted in a mesh shape at the same time, so that the working electrode can be obtained in a shorter time. 5 and the current collecting region 19 can be formed.

<Second embodiment>
As shown in FIGS. 4 and 5, the dye-sensitized photoelectric conversion element 1B (1) according to the second embodiment of the present invention includes a power generation unit 2, an extraction electrode 6a, and an extraction electrode 35a that are rectangular in plan view. In this configuration, electrons generated in the power generation unit 2 are collected through an extraction electrode 6 a that is extracted from one side of the power generation unit 2.
The power generation unit 2 is configured such that a plate-like working electrode 5 and a counter electrode 6 having a rectangular shape in plan view are superposed via particles 28 made of an insulator contained in an electrolyte 18.

  The working electrode 5 is composed of a transparent conductive substrate 35 and a porous semiconductor layer 13 which is disposed on the conductive surface of the transparent conductive substrate 35 and carries a sensitizing dye. The semiconductor layer 13 is impregnated with the electrolyte 18 together with the sensitizing dye. The porous oxide semiconductor layer 13 can be formed on the transparent conductive substrate 35 by, for example, a screen printing method. The transparent conductive substrate 35 is provided with an extraction electrode 35 a and extends outside the power generation unit 2.

The counter electrode 6 is a plate-like conductive base material, and is overlapped with the working electrode 5 via particles 28 made of an insulator contained in the electrolyte 18. The counter electrode 6 has an extraction electrode 6 a that forms a pair with the extraction electrode 35 a, and the extraction electrode 6 a extends to the outside of the power generation unit 2.
The electrolyte 18 including the working electrode 5, the counter electrode 6, and the particles 28 made of an insulator interposed therebetween is stored in the storage bag 14, and the storage bag 14 is filled with the electrolyte 18.

The transparent conductive substrate 35 has a transparent conductive layer formed on at least one surface of the transparent substrate.
As the transparent substrate used in this embodiment, a plate made of a light-transmitting material is used, and glass, polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyethersulfone, etc. are usually used as transparent substrates for solar cells. Any substrate can be used as long as it is selected, and an appropriate substrate may be selected in consideration of resistance to an electrolyte. However, a substrate having as high a light transmission as possible is preferable for use.

A transparent conductive layer made of metal, carbon, a conductive metal oxide layer or the like is formed on at least one surface of the transparent substrate. When forming a metal layer or a carbon layer, it is preferable to have a structure that does not significantly impair transparency, and the type of metal is also appropriately selected from the viewpoint that a thin film that does not impair conductivity and transparency can be formed.
As the conductive metal oxide, for example, ITO, SnO ₂ , fluorine-doped SnO ₂ or the like can be used.
As a preferable transparent conductive substrate, for example, conductive glass on which fluorine-doped SnO ₂ , ITO or the like is deposited can be exemplified.

  The description of the sensitizing dye, the porous oxide semiconductor layer 13, the counter electrode 6, the electrolyte 18, the particles 28 made of an insulator, and the storage bag 14 are the same as those described in the first embodiment.

  In the dye-sensitized photoelectric conversion element 1B (1) according to the second embodiment of the present invention, similarly to the dye-sensitized photoelectric conversion element 1A (1) according to the first embodiment described above, the particles 28 made of an insulator are used. However, it functions as a separator that is interposed between the working electrode 5 and the counter electrode 6 together with the electrolyte 18 to electrically insulate the working electrode 5 from the counter electrode 6. And compared with the conventional dye-sensitized photoelectric conversion element which uses the porous flat film as a separator, photoelectric conversion can be performed with the outstanding efficiency.

As the dye-sensitized photoelectric conversion element 1 according to the present invention, the first embodiment described above is preferable because of excellent flexibility and photoelectric conversion efficiency.
That is, in the dye-sensitized photoelectric conversion element 1 according to the present invention, the working electrode 5 has a plurality of first base material 8 and second base material 9 that are conductive and have a linear shape. Those composed of rare regions are preferred.

(Example)
A dye-sensitized photoelectric conversion element having the structure shown in FIG. 1 was produced.
First, Ti coated Cu wire drawn to a diameter of 0.05 mm was woven into a mesh electrode having a dense plain weave structure by a loom as shown in FIG. The size of the area of the rectangular network structure in which the vertical and horizontal Ti-coated Cu wires are woven is 10 cm × 10 cm, and the number of Ti-coated Cu wires is 1500 to 2000 in the vertical and horizontal directions.
The number of Ti-coated Cu wires constituting the current collector was 1500 to 2000, and the width of the current collector was 1 cm.

<Production of working electrode>
A TiO ₂ paste (manufactured by JGC Catalysts & Chemicals Co., Ltd .; PNT-21NR) was applied to this power generation unit by a squeegee method, and sintered in an electric furnace at 500 ° C. for 1 hour. A porous TiO ₂ film having a thickness of about 15 μm was formed on the mesh electrode.
Note that portions other than the power generation unit (10 cm × 10 cm) constituting the working electrode were masked with a tape or the like so that the paste of TiO ₂ was not applied.

  Next, the Cu foil formed longer than the length in the longitudinal direction of the current collector is overlapped on the current collector, and further sandwiched between Ti foils, and then resistance welding is performed using a predetermined spot welder. Crimping was performed using this method. The spot welding interval was about 2 mm along the longitudinal direction of the current collector. Thereafter, the current collector was coated by being immersed in a polyimide resin. In addition, it deaerated by the vacuum at the time of immersion.

Subsequently, the power generation unit was kept in an oven at 120 ° C. for 10 minutes to evaporate the adsorbed water, and then the ruthenium dye {manufactured by Solaronix; RutheAlum 535-bisTBA (generally called N719)}. It was immersed in a 3 mM acetonitrile / tert-butanol = 1: 1 solution and allowed to stand at room temperature for 24 hours to carry the dye on the TiO ₂ surface. After pulling up from the dye solution, it was washed with the above mixed solvent and used as a working electrode.

<Production of counter electrode>
On the other hand, a counter electrode was formed by forming a Pt layer having a thickness of about 200 nm on a rectangular Ti plate (10 cm × 10 cm) having a thickness of about 0.1 mm using a ternary RF sputtering apparatus. In addition, an extraction electrode was provided at the end.

<Production of electrolyte>
In 10 mL of methoxypropionitrile (MPN), 0.377 g (0.15 M) of I2, 2.128 g (0.8 M) of DMPImI, 0.1182 g (0.1 M) of GuSCN, and 0.6609 g of NMBI ( 0.5M) was dissolved to obtain an electrolytic solution.

  Spherical soda-lime glass particles having the diameters shown in Table 1 were mixed in the ratio shown in Table 1 with respect to the electrolytic solution, and the respective electrolytes were designated as electrolytes 1-17.

<Production of cell>
In the storage bag made of PET, the working electrode and the counter electrode are inserted to face each other, and after the electrolytes 1 to 17 are injected, they are sealed with an adhesive, and Examples 1 to 8 and Comparative Examples 1 to 1 are used. No. 9 dye-sensitized photoelectric conversion element (cell).
On the other hand, the dye-sensitized photoelectric conversion element (cell) of Comparative Example 10 was produced as follows.
After the working electrode and the counter electrode are made to face each other and a porous flat membrane made of polyolefin having a thickness of 20 μm is sandwiched therebetween, inserted into a storage bag made of PET, and the electrolytic solution is injected And sealed with an adhesive.

<Evaluation of photoelectric conversion efficiency>
Irradiating light to each of the dye-sensitized photoelectric conversion elements of Examples 1 to 8 and Comparative Examples 1 to 9 manufactured as described above using a solar simulator (AM1.5, 100 mW / cm ² ). Then, the current potential curve was measured, and the photoelectric conversion efficiency was obtained. The results are also shown in Table 1.
Moreover, when the photoelectric conversion efficiency of the dye-sensitized photoelectric conversion element of Comparative Example 10 was determined under the same conditions, it was 3.2%. In addition, about Comparative Examples 1-6 which could not insulate a working electrode and a counter electrode, since it did not function as a photoelectric conversion element, the photoelectric conversion efficiency was not measured.

  From the above results, the dye-sensitized photoelectric conversion elements of Examples 1 to 8 according to the present invention are all superior to or equivalent to the dye-sensitized photoelectric conversion elements of Comparative Examples 1 to 10. It is clear that it has efficiency.

  The present invention is widely applicable to dye-sensitized photoelectric conversion elements.

DESCRIPTION OF SYMBOLS 1 ... Dye-sensitized photoelectric conversion element, 2 ... Power generation part, 3 ... Current collection part, 4 ... Current collection wiring, 5 ... Working electrode, 6 ... Counter electrode, 8 ... 1st base material, 9 ... 2nd base material DESCRIPTION OF SYMBOLS 13 ... Porous oxide semiconductor layer, 14 ... Storage bag, 18 ... Electrolyte, 19 ... Current collection area | region, 20 ... Outer periphery base material, 21 ... Cu foil, 22 ... Ti foil, 23 ... Molten part, 24 ... Spot welding Part, 25 ... electrode for resistance welding, 28 ... particle made of insulator, 30 ... first side, 31 ... second side, 32 ... third side, 33 ... fourth side, 35 ... transparent conductive substrate, 100 ... Conventional dye-sensitized conversion element, 102 ... power generation section, 103 ... current collection section, 104 ... current collection wiring, 105 ... working electrode, 106 ... counter electrode, 108 ... first base material, 109 ... second base material, DESCRIPTION OF SYMBOLS 110 ... Separator, 113 ... Porous oxide semiconductor layer, 114 ... Storage bag, 118 ... Electrolyte, 120 ... Outer periphery base material, 121 ... Cu foil, 22 ... Ti foil, 123 ... melting unit.

Claims (3)

A dye-sensitized photoelectric conversion element in which a working electrode and a counter electrode having conductivity are arranged via an electrolyte,
The working electrode and the counter electrode are insulated by particles made of an insulator contained in the electrolyte, and the particles made of the insulator have a spherical shape with a maximum outer diameter of 40 μm or more and 120 μm or less. A dye-sensitized photoelectric conversion element.   The said working electrode is comprised from the area | region where the some 1st base material and 2nd base material which have electroconductivity and make linear form are knitted in mesh shape. Dye-sensitized photoelectric conversion element. The particles made of the insulator are spherical glass particles,
3. The dye-sensitized photoelectric conversion element according to claim 1, wherein the dye-sensitized photoelectric conversion element is contained in the electrolyte at a ratio of 1.0% by mass or more and 5.0% by mass or less.

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