JP2013093174A - Dye sensitized photoelectric conversion element and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dye-sensitized photoelectric conversion element which can improve power generation characteristics while reducing manufacturing costs, and a manufacturing method therefor.SOLUTION: The dye-sensitized photoelectric conversion element comprises: a first substrate; a first electrode disposed on the first substrate; a catalyst layer formed on the first electrode and exhibiting catalytic activity against an oxidation-reduction electrolyte; an electrolyte adjoining the catalyst layer and consisting of an oxidation-reduction electrolyte dissolved in a solvent; a porous semiconductor layer adjoining the electrolyte and including semiconductor particulates and dye molecules; a second electrode disposed on the porous semiconductor layer; and an encapsulating material disposed between the first and the second substrates and encapsulating the electrolyte. The catalyst layer is composed with a conductive thin film containing one of metal oxide particulates having corrosion resistance against active carbon and electrolytes and an organic compound having conductivity.

Description

  The present invention relates to a dye-sensitized solar cell (DSC) and a manufacturing method thereof, and more particularly, to a dye-sensitized photoelectric conversion device capable of improving power generation characteristics and a manufacturing method thereof.

  In recent years, DSC has attracted attention as an inexpensive and high-performance photoelectric conversion element (solar cell). DSC was developed by Grezell of Lausanne University of Technology in Switzerland, and has the advantages of high photoelectric conversion efficiency and low manufacturing cost by using titanium oxide carrying a sensitizing dye on the surface. It is expected as a photoelectric conversion element of the next generation. This photoelectric conversion element is also called a wet photoelectric conversion element because an electrolytic solution is sealed inside.

  DSC is packed between a working electrode having a porous titanium oxide layer carrying a sensitizing dye on its surface, a counter electrode disposed opposite the titanium oxide layer of the working electrode, and the working electrode and the counter electrode. An electrolyte solution (see, for example, Patent Document 1).

JP-A-11-135817

  By the way, in DSC, platinum (Pt) is generally used as a counter electrode material, which can cause an oxidation-reduction reaction to proceed smoothly at an electrode.

  However, the platinum film formed by the vacuum film-forming method has a problem that it requires enormous maintenance costs and is inferior in productivity, resulting in an increase in manufacturing cost. In particular, when a large-area DSC is produced, a reduction in manufacturing cost is required.

  In addition, it is immersed in a platinum precursor solution such as platinum chloride solution, or is applied by spraying, and a local film is formed by screen printing, followed by a baking treatment to promote a redox reaction instead of a film. It is also possible to obtain fine platinum particles having a suitable particle size. It is possible to suppress the platinum consumption and form the counter electrode material at a low cost, but with only the platinum particles formed by the above production method, the oxidation-reduction reaction does not proceed efficiently, especially as the amount of incident light on the DSC increases. There was a problem that the power generation efficiency dropped significantly.

  On the other hand, a carbon electrode having a low cost and a high catalytic ability has been proposed as a counter electrode material. This is a porous carbon material such as carbon black particles, graphite particles, activated carbon, etc., dispersed in water or an organic solvent and applied to a substrate, or in combination with a resin binder to form a film by screen printing. I can do it. In particular, film formation by screen printing is excellent in productivity because local film formation is possible. Since the porous carbon electrode can take the electrolyte solution into its pores, the electrode area is larger and the catalytic property is greatly improved as compared with the counter electrode state supported by the platinum particles. It also has the advantage of being chemically stable.

  However, in the DSC use environment, assuming indoor use, the photovoltaic power generation characteristics by incident light such as room light have an insulation resistance (in the solution or paste film for forming the carbon film). For example, it has been found that there is a problem that the resulting Filling Factor (hereinafter referred to as “FF”) and energy conversion efficiency η are low due to the influence of a resin binder.

  An object of the present invention is to provide a dye-sensitized photoelectric conversion element capable of improving the power generation characteristics while reducing the catalyst production cost by carbon and a method for producing the same.

  According to one aspect of the present invention for achieving the above object, the first substrate, the first electrode disposed on the first substrate, and the catalytic activity for the redox electrolyte formed on the first electrode. A catalyst layer in contact with the catalyst layer, an electrolyte solution in which the redox electrolyte is dissolved in a solvent, a porous semiconductor layer in contact with the electrolyte solution, comprising semiconductor fine particles and pigment molecules, and the porous semiconductor layer A second electrode disposed; a second substrate disposed on the second electrode; and a sealing material disposed between the first substrate and the second substrate and sealing the electrolyte. In addition, a dye-sensitized photoelectric conversion element is provided in which the catalyst layer is formed of a conductive thin film having one of activated carbon and metal oxide fine particles having corrosion resistance to the electrolytic solution, or an organic material having conductivity.

  According to another aspect of the present invention, a step of forming a first electrode on a first substrate, and a metal oxide fine particle having a corrosion resistance against activated carbon and an electrolytic solution as a catalyst layer on the first electrode, or a conductive layer. A step of forming a conductive thin film having one of organic materials having a property, a step of forming a second electrode on the second substrate, and a step of forming a porous semiconductor layer comprising semiconductor fine particles on the second electrode; A step of immersing the porous semiconductor layer in a dye solution to adsorb dye molecules; a counter electrode substrate on which the first electrode and the catalyst layer are formed on a first substrate; and a second electrode on a second substrate. And a working electrode substrate having the porous semiconductor layer adsorbed with the dye molecules adhering to each other through an inter-electrode electrode between the substrates and a sealing material for serial arrangement, and the counter electrode substrate, Injection of electrolyte between the working electrode substrate That step in the method of manufacturing the dye-sensitized photoelectric conversion device having a are provided.

  According to another aspect of the present invention, a step of forming a plurality of first electrodes on the first substrate at a predetermined interval, and a metal having corrosion resistance against activated carbon and an electrolytic solution as a catalyst layer on each first electrode. A step of forming a conductive thin film having one of oxide fine particles or a conductive organic material, a step of forming a plurality of second electrodes opposed to the first electrodes on a second substrate, Forming a porous semiconductor layer comprising semiconductor fine particles on each second electrode; adsorbing dye molecules to each porous semiconductor layer; and a plurality of first electrodes and catalyst layers on a first substrate. And a working electrode substrate on which a plurality of second electrodes and the porous semiconductor layer on which the dye molecules are adsorbed are formed on the second substrate, each of which serves as a dye-sensitized photoelectric conversion element Bonding through a sealing material to partition Breaking along the scribe line, a scribe process for forming a scribe line on the first substrate or the second substrate, and a scribe line for separating each cell to be a dye-sensitized photoelectric conversion element, There is provided a method for producing a dye-sensitized photoelectric conversion element comprising a separation step of separating and a step of injecting an electrolyte into each cell of the separated dye-sensitized photoelectric conversion element.

  According to the present invention, it is possible to provide a dye-sensitized photoelectric conversion element capable of improving power generation characteristics while reducing the manufacturing cost and a method for manufacturing the same.

1 is a schematic cross-sectional structure diagram of a dye-sensitized photoelectric conversion element according to a first embodiment. FIG. 2 is a schematic structural diagram of semiconductor fine particles of the porous semiconductor layer of FIG. 1. Explanatory drawing of the operation principle of the dye-sensitized photoelectric conversion element according to the first embodiment. Explanatory drawing of the operation principle based on the charge exchange reaction in the electrolyte solution of the dye-sensitized photoelectric conversion element according to the first embodiment. In the dye-sensitized photoelectric conversion element which concerns on 1st Embodiment, the energy potential diagram between a porous semiconductor layer (12) / dye molecule | numerator (32) / electrolyte solution (14). FIG. 8 is an energy potential diagram between a dye molecule (32) / electrolyte solution (14) in the dye-sensitized photoelectric conversion element according to the first embodiment, and is an enlarged view of a portion J in FIG. The typical cross-section figure of the working electrode of the dye-sensitized photoelectric conversion element which concerns on 1st Embodiment. The typical cross-section figure of the counter electrode of the dye-sensitized photoelectric conversion element which concerns on 1st Embodiment. The typical cross-section figure which shows the state which bonded together the working electrode and counter electrode of the dye-sensitized photoelectric conversion element which concern on 1st Embodiment through the sealing material. The typical cross-section figure which shows the state after inject | pouring electrolyte solution into the structure bonded together in FIG. (A) The perspective view which shows the manufacturing process of the working electrode of the dye-sensitized photoelectric conversion element which concerns on 1st Embodiment, (b) The perspective view which shows a mode that the porous semiconductor layer was formed on the 2nd board | substrate, ( c) A perspective view showing a step of immersing the dye solution in the porous semiconductor layer. (A) The perspective view which shows the manufacturing process of the counter electrode of the dye-sensitized photoelectric conversion element which concerns on 1st Embodiment, (b) The perspective view which shows a mode that the catalyst layer was formed on the glass substrate which has an injection hole and a vent hole. Figure. (A) Perspective view showing a state in which the working electrode and the counter electrode are bonded together via a sealing material, which is a step of the manufacturing process of the dye-sensitized photoelectric conversion element according to the first embodiment, and (b) electrolysis The perspective view which shows the state which inject | pours a liquid, (c) The typical cross-section figure which shows the dye-sensitized photoelectric conversion element which concerns on 1st Embodiment manufactured. The typical cross-section figure which is one process of the manufacturing process of the dye-sensitized photoelectric conversion element which concerns on 2nd Embodiment, and shows the state which formed the 2nd electrode on the 2nd board | substrate. FIG. 6 is a process of manufacturing a dye-sensitized photoelectric conversion element according to the second embodiment, and shows a state where inter-electrode wirings for forming a series arrangement with a cathode electrode are formed on a second electrode. FIG. The typical cross-section figure showing the state where it was one process of the manufacturing process of the dye sensitizing photoelectric conversion element concerning a 2nd embodiment, and formed the porous semiconductor layer on each 2nd electrode. A step of manufacturing a dye-sensitized photoelectric conversion element according to the second embodiment, in which inter-substrate wiring and a catalyst layer for forming a series arrangement with an anode electrode are formed on a first electrode The typical cross-section figure which shows the state which was made. It is one process of the manufacturing process of the dye-sensitized photoelectric conversion element which concerns on 2nd Embodiment, Comprising through the interelectrode wiring for making a working electrode and a counter electrode into a serial arrangement with a sealing material FIG. FIG. 19 is a schematic cross-sectional structure diagram showing a state after injecting an electrolytic solution into the structure bonded in FIG. 18, which is one step of the manufacturing process of the dye-sensitized photoelectric conversion element according to the second embodiment. The top view which shows the state by which the several 2nd electrode was formed on the 2nd board | substrate about the manufacturing method of the dye-sensitized photoelectric conversion element which concerns on 3rd Embodiment. The top view which is one process of the manufacturing method of the dye-sensitized photoelectric conversion element which concerns on 3rd Embodiment, and shows the state in which the several 1st electrode was formed on the 1st board | substrate. The top view which is 1 process of the manufacturing method of the dye-sensitized photoelectric conversion element which concerns on 3rd Embodiment, and shows the state which bonded together the working electrode and the counter electrode through the sealing material. FIG. 23 is a schematic cross-sectional structure diagram taken along the line II of FIG. 22 for a method of manufacturing a dye-sensitized photoelectric conversion element according to a third embodiment. The top view which is one process of the manufacturing method of the dye-sensitized photoelectric conversion element which concerns on 3rd Embodiment, and shows the state which formed the scribe line of the horizontal direction. The top view which shows one state of the manufacturing method of the dye-sensitized photoelectric conversion element according to the third embodiment and shows a state in which a vertical scribe line is further formed. The time chart which shows the temperature conditions at the time of baking a catalyst layer. Explanatory drawing of the operation principle of the dye-sensitized photoelectric conversion element according to the first embodiment. (A) The schematic diagram which shows the precipitation state of Pt particle | grains by heat processing, (b) The enlarged view of the B section of FIG. The graph which shows the electric power generation characteristic at the time of irradiating 200 lx white light to the dye-sensitized photoelectric conversion element which concerns on 1st Embodiment. The graph which shows the electric power generation characteristic at the time of irradiating 800 lx white light to the dye-sensitized photoelectric conversion element which concerns on 1st Embodiment. The graph which shows the electric power generation characteristic at the time of irradiating 5000 lx white light to the dye-sensitized photoelectric conversion element which concerns on 1st Embodiment.

  Next, embodiments will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  Further, the embodiments described below exemplify apparatuses and methods for embodying the technical idea of the present invention, and the embodiments of the present invention include the material, shape, structure, The layout is not specified as follows. Various modifications can be made to the embodiment of the present invention within the scope of the claims.

  In the dye-sensitized photoelectric conversion element according to the following embodiment, “transparent” is defined as having a transmittance of about 50% or more. Further, “transparent” is also used to mean colorless and transparent to visible light in the dye-sensitized photoelectric conversion element according to the embodiment. Visible light corresponds to a wavelength of about 360 nm to 830 nm and an energy of about 3.45 eV to 1.49 eV, and is transparent if the transmittance is 50% or more in this region.

[First embodiment]
(Dye-sensitized photoelectric conversion element)
A schematic cross-sectional structure of the dye-sensitized photoelectric conversion element 200 according to the first embodiment is expressed as shown in FIG.

  As shown in FIG. 1, the working electrode 100 applied to the dye-sensitized photoelectric conversion element 200 according to the dye-sensitized photoelectric conversion element 200 according to the first embodiment is formed on the glass substrate 22 and the glass substrate 22. A first electrode (counter electrode) 18 disposed and a catalyst layer 21 disposed on the first electrode 18 are provided.

  As illustrated in FIG. 1, the dye-sensitized photoelectric conversion element 200 includes a glass substrate 22, a first electrode 18 provided on the glass substrate 22, a catalyst layer 21 disposed on the first electrode 18, a catalyst The charge transport layer 14 includes an electrolyte that is in contact with the layer 21 and includes an electrolyte made by mixing a solvent and a plurality of types of redox electrolytes.

  Furthermore, as shown in FIG. 1, the dye-sensitized photoelectric conversion element 200 is shown in FIG. 2 in which the second substrate 20, the transparent electrode 10 disposed on the second substrate 20, and the transparent electrode 10 are disposed. A porous semiconductor layer 12 having such semiconductor fine particles 2 and dye molecules 4, an electrolyte solution 14 in contact with the porous semiconductor layer 12, a redox electrolyte dissolved in a solvent, and a first electrode 18 in contact with the electrolyte solution 14. The first substrate 22 disposed on the first electrode 18 and the sealing material 16 disposed between the second substrate 20 and the first substrate 22 and sealing the electrolyte solution 14 are provided.

The transparent electrode 10 and the first electrode 18 are formed of transparent electrodes such as FTO, ZnO, ITO, SnO ₂ , for example.

  The catalyst layer 21 can be formed by firing a paste layer containing fine particles of metal oxide having corrosion resistance against activated carbon and the electrolytic solution 14.

The metal oxide having corrosion resistance to electrolytic _solution, can be used _{TiO 2, ZnO, SnO 2,} WO 3 and the like.

  The catalyst layer 21 formed by firing the paste layer as described above loses its insulating properties because the resin binder contained in the paste does not function by firing at a high temperature (for example, 400 to 450 ° C.), and the first electrode ( Charge transfer on the surface of the counter electrode 18 and charge exchange reaction with the electrolytic solution 14 can be rapidly advanced. As a result, the power generation characteristics of the dye-sensitized photoelectric conversion element 200, particularly F.R. F. Can be improved.

Conventionally, when the resin binder does not function due to high-temperature firing, the adhesion between the activated carbon film and the substrate is lowered, and the activated carbon film is easily peeled off. On the other hand, in the present embodiment, instead of the configuration in which activated carbon is fixed by a conventional resin binder, fine particles of metal oxide such as TiO ₂ , ZnO, SnO _{2 and} WO ₃ added in the activated carbon paste ( By sintering the nanoparticles, the activated carbon is bonded and fixed by necking (covalent bonding).

  As a result, the catalyst layer 21 can maintain the high catalytic properties of the activated carbon and ensure adhesion with the first electrode 18.

  Moreover, the film | membrane peeling of the catalyst layer 21 after baking can be suppressed by making the density | concentration of the activated carbon in the paste containing the microparticles | fine-particles of activated carbon and a metal oxide into about 20 mass%, for example.

  Moreover, by controlling the film thickness of the catalyst layer 21, a relatively large effective area (surface area) due to the activated carbon particles can be secured, and the electron transfer reaction on the surface of the first electrode (counter electrode) 18 can be rapidly advanced. be able to. Therefore, the dye-sensitized photoelectric conversion element 200 according to the first embodiment is not limited to a high illuminance light source such as under sunlight, but has high catalytic properties even under a relatively low illuminance such as indoor light. Photovoltaic properties equivalent to those using platinum (Pt) can be maintained. In addition, the experimental result regarding the power generation characteristic of the dye-sensitized photoelectric conversion element 200 according to the first embodiment will be described later with reference to FIGS.

Further, the activated carbon and the fine particles of metal oxides such as TiO ₂ , ZnO, SnO ₂ , and WO ₃ constituting the catalyst layer 21 are relatively cheaper than platinum (Pt), and the film of platinum (Pt) is formed. There is no need to use a vacuum film formation method, and film formation can be performed by applying a printing method such as screen printing, as will be described later. Therefore, the manufacturing cost is reduced and the unit price of the dye-sensitized photoelectric conversion element is reduced. Can be greatly reduced.

  Furthermore, the catalyst layer 21 can further improve the conductivity between particles by containing a conductive polymer (such as PEDOT: PSS) in the activated carbon, and in this case, while reducing the manufacturing cost, The power generation characteristics can be improved.

The porous semiconductor layer 12 may be formed using a material such as TiO ₂ , ZnO, WO ₃ , InO ₃ , ZrO ₂ , Ta ₂ O ₃ , Nb ₂ O ₃ , SnO ₂ . In particular, TiO ₂ (anatase type, rutile type) that is inexpensive from the viewpoint of efficiency is mainly used.

A schematic structure of the semiconductor fine particles 2 of the porous semiconductor layer 12 of FIG. 1 is expressed as shown in FIG. As shown in FIG. 2, in the porous semiconductor layer 12, semiconductor fine particles 2 made of TiO ₂ or the like are bonded to each other to form a complex network. The dye molecules 4 are adsorbed on the surface of the semiconductor fine particles 2. A large number of pores having a size of 100 nm or less exist in the porous semiconductor layer 12.

(Operating principle)
The operation principle of the dye-sensitized photoelectric conversion element 200 according to the first embodiment is expressed as shown in FIG.

  When the following reactions (a) to (d) occur continuously, an electromotive force is generated, and a current is conducted to the load 24.

(A) The dye molecule 32 absorbs a photon (hν), emits an electron (e ⁻ ), and the dye molecule 32 becomes an oxidized DO.

(B) The reduced redox electrolyte 26 represented by Re diffuses in the porous semiconductor layer 12 and approaches the oxidized dye molecule 32 represented by DO.

(C) Electrons (e ⁻ ) are supplied from the redox electrolyte 26 to the dye molecules 32. The redox electrolyte 26 becomes an oxidized redox electrolyte 28 represented by Ox, and the dye molecule 32 becomes a reduced dye molecule 30 represented by DR.

(D) The redox electrolyte 28 diffuses in the direction of the first electrode 18 and is supplied with electrons from the first electrode 18 to become a redox electrolyte 26 of a reductant represented by Re.

  The redox electrolyte 26 needs to approach the vicinity of the dye molecule 32 while diffusing in the complicated space in the porous semiconductor layer 12.

  Moreover, the principle of operation based on the charge exchange reaction in the electrolyte solution 14 of the dye-sensitized photoelectric conversion element 200 according to the first embodiment is expressed as shown in FIG.

First, when light is irradiated from the outside, photons (hν) react with the dye molecules 32, and the dye molecules 32 transition from the ground state to the excited state. The excited electrons (e ⁻ ) generated at this time are injected into the conduction band of the porous semiconductor layer 12 made of TiO ₂ . The electrons (e ⁻ ) conducted through the porous semiconductor layer 12 conduct through the load 24 of the external circuit from the transparent electrode 10 and move to the first electrode 18. Electrons (e ⁻ ) injected from the first electrode 18 into the electrolytic solution 14. Charge exchange is performed with the iodine redox electrolyte (I ⁻ / I ₃ ⁻ ) in the electrolytic solution 14. The iodine redox electrolyte (I ⁻ / I ₃ ⁻ ) diffuses in the electrolytic solution 14 and reacts with the dye molecules 32 again. Here, the charge exchange reaction proceeds according to 3I ⁻ → I ₃ ⁻ + 2e ^{− on the} surface of the dye molecule, and proceeds according to I ₃ ⁻ + 2e ⁻ → 3I ^{− on} the first electrode 18.

The electrolytic solution 14 uses, for example, acetonitrile as a solvent, and as an electrolyte in this case, for example, iodine exists as an iodine redox electrolyte I ₃ ⁻ in the electrolytic solution 14. Further, as an electrolyte, for example, an iodide salt (lithium iodide, potassium iodide, etc.) exists as an iodine redox electrolyte I ⁻ in the electrolytic solution 14. Further, an additive (for example, TBP: tertiary butyl pyridine) may be applied to the electrolytic solution 14 as a reverse electron transfer inhibiting solution.

  The electrolytic solution 14 can be constituted by dissolving the above solute and additive in a solvent (acetonitrile). In addition, said material is applicable to wet DSC etc., Comprising material differs, when normal temperature molten salt (ionic liquid) and a solid electrolyte are used.

  In the dye-sensitized photoelectric conversion element 200 according to the first embodiment, the solvent is a liquid that dissolves an electrolyte and an additive that will be described later, has a high boiling point, high chemical stability, and a high dielectric constant (the electrolyte is good). It is desirable to have a low viscosity. For example, it may be composed of acetonitrile, propylene carbonate, γ-butyrolactone, methoxyacetonitrile, propionitrile, ethylene carbonate, propylene carbonate, and the like.

  In the dye-sensitized photoelectric conversion element 200 according to the first embodiment, the energy potential diagram between the porous semiconductor layer (12) / the dye molecule (32) / the electrolyte solution (14) is expressed as shown in FIG. Is done. Moreover, it is an energy potential diagram between a dye molecule (32) / electrolyte solution (14), Comprising: The enlarged view of J part of FIG. 5 is represented as shown in FIG.

When light is irradiated from the outside, photons (hν) react with the dye molecules 32, and the dye molecules 32 transition from the ground state HOMO to the excited state LUMO. The excited electrons (e ⁻ ) generated at this time are injected into the conduction band of the porous semiconductor layer 12 made of TiO ₂ . The electrons (e ⁻ ) conducted through the porous semiconductor layer 12 conduct through the load 24 of the external circuit from the transparent electrode 10 and move to the first electrode 18. Electrons (e ⁻ ) injected from the first electrode 18 into the electrolytic solution 14 are exchanged with the iodine / mixed redox electrolyte in the electrolytic solution 14. The iodine-bromine mixed redox electrolyte diffuses in the electrolyte solution 14 and reacts with the dye molecules 32 again.

The potential difference between the oxidation-reduction level E _RO of the electrolytic solution 14 and the Fermi level E _f of the porous semiconductor layer 12 is the maximum electromotive force V _MAX . The value of the maximum electromotive force V _MAX varies depending on the redox electrolyte of the electrolytic solution 14. In the case of a single redox electrolyte system (iodine redox electrolyte), for example, 0.9 V (I, N719). When the electrolytic solution 14 contains a mixed redox electrolyte of iodine / bromine, as shown in FIG. 6, the redox potential of the mixed redox electrolyte is adjusted by adjusting the mixing ratio to oxidize the iodine redox electrolyte. It can be adjusted to any value between the reduction potential and the redox potential of the bromine redox electrolyte.

As shown in FIG. 6, when the mixing ratio of bromine redox electrolyte in the electrolytic solution 14 is zero, the redox level E _RO = 0.53 V (I / I ₃ ⁻ ), whereas iodine redox When the mixing ratio of the electrolyte is zero, the oxidation-reduction level E _RO = 1.09 V (Br / Br ₃ ⁻ ). The value of this period of the gap energy _{E ga} is a 1.09-0.53 = 0.56V.

When the value of the potential difference E _gh between the HOMO level and the oxidation-reduction level E _RO is large, a voltage loss occurs when obtaining the maximum electromotive force V _MAX . If the value of the potential difference _{E gh} the HOMO level and the redox level _{E RO} is low, electrons to the dye molecules 32 from the electrolyte 14 (e ^-) transfer is inhibited.

Therefore, in order to efficiently conduct electrons (e ⁻ ) from the electrolytic solution 14 to the dye molecule 32 side and to suppress voltage loss in obtaining the maximum electromotive force V _MAX , the level of the redox level E _RO Is preferably higher than the HOMO level of the dye molecule 32 and the potential difference E _gh is made as small as possible.

  As shown below, in an electrolytic solution comprising an iodine-bromine mixed redox electrolyte obtained by mixing an iodine redox electrolyte and a bromine redox electrolyte, compared to the case where the iodine redox electrolyte is used alone, The open-circuit voltage value increases according to the amount of bromine redox electrolyte added. Compared with iodine redox electrolyte, bromine redox electrolyte has positive (positive) redox potential, and the redox potential of iodine-bromine mixed redox electrolyte depends on the amount of bromine redox electrolyte added. This is for shifting to the positive side.

(Configuration of dye-sensitized photoelectric conversion element)
Next, a configuration example of the dye-sensitized photoelectric conversion element 200 according to the first embodiment will be described with reference to FIGS.

  As shown in FIG. 7, a working electrode 100 composed of a transparent electrode 10 and a porous semiconductor layer 12 is formed on a second substrate 20 composed of a glass substrate or a flexible plastic substrate.

The transparent electrode 10 is formed by, for example, sputtering film formation of FTO, ZnO, ITO, SnO ₂ or the like.

  The porous semiconductor layer 12 can be formed using, for example, screen printing technology, spin coating technology, dipping, spray coating technology, or the like. A method for forming the porous semiconductor layer 12 will be described later.

  Further, as shown in FIG. 8, the first electrode 18 and the catalyst layer 21 are formed on the first substrate 22 composed of a glass substrate or a flexible plastic substrate.

The first electrode 18 is formed by, for example, sputtering film formation of FTO, ZnO, ITO, SnO ₂ or the like.

  The catalyst layer 21 can be formed using a screen printing technique or the like. The method for forming the catalyst layer 21 will be described later.

  Then, as shown in FIG. 9, the second substrate 20 is bonded onto the first substrate 22 via the sealing material 16.

  The schematic cross-sectional structure diagram of FIG. 10 shows the structure of the dye-sensitized photoelectric conversion element 200 completed by injecting the electrolyte solution 14 into the structure bonded through the sealing material 16 as shown in FIG.

  9 and 10, the anode electrode 3A serving as the positive electrode of the dye-sensitized photoelectric conversion element 200 is formed on the first electrode 18 of the first substrate 22 and the transparent electrode 10 of the second substrate 20. On the top, the cathode electrode 3K that is the negative electrode of the dye-sensitized photoelectric conversion element 200 is formed.

(Method for producing dye-sensitized photoelectric conversion element)
Next, a method for manufacturing the dye-sensitized photoelectric conversion element 200 according to the first embodiment will be described with reference to FIGS.

  First, an example of forming the porous semiconductor layer 12 by screen printing will be described with reference to FIG.

  As shown in FIG. 11A, a mask member 23a having an opening corresponding to the porous semiconductor layer to be formed is positioned and set on the second substrate 20 after the transparent electrode 10 is formed. . The thickness of the mask member 23a is selected according to the target thickness of the porous semiconductor layer to be formed.

Next, paste 12a containing fine particles such as TiO ₂ , ZnO, WO ₃ , InO ₃ , ZrO ₂ , Ta ₂ O ₃ , Nb ₂ O ₃ , SnO ₂ is applied onto the mask member 23a, and the squeegee 25a is moved in the direction of the arrow. It is moved and the paste 12a is filled in the opening of the mask member 23a.

  Next, as shown in FIG. 11B, the porous semiconductor layer 12 is formed by baking the paste layer at a predetermined temperature after removing the mask member 23a.

  Subsequently, as illustrated in FIG. 11C, the porous semiconductor layer 12 is adsorbed with the dye by immersing the porous semiconductor layer 12 in the dye solution 45 placed in the container 44.

  As the dye, a red die (N719), a black die (N749), or the like can be applied.

  Thereby, the working electrode 100 including the porous semiconductor layer 12 on which the dye is adsorbed is created.

  Next, an example of forming the catalyst layer 21 by screen printing will be described with reference to FIG.

  As shown in FIG. 12A, a mask member 23b having an opening corresponding to the catalyst layer to be formed is positioned and set on the first substrate 22 after the first electrode 18 is formed. Note that the thickness of the mask member 23b is selected in accordance with the target thickness of the catalyst layer to be formed.

Next, paste 21a containing fine particles of activated carbon and metal oxides such as TiO ₂ , ZnO, SnO _{2, and} WO ₃ is applied onto mask member 23b, squeegee 25b is moved in the direction of the arrow, and paste 21a is applied to mask member 23b. The inside of the opening is filled.

  Next, as shown in FIG. 12B, after removing the mask member 23b, the catalyst layer 21 is formed by firing the paste layer at a predetermined temperature.

  It should be noted that an injection hole 22a for the electrolyte solution 14 and an exhaust hole 22b for exhausting air when injecting are drilled at two opposite corners of the first substrate 22 by a drill or the like. In addition, when adopting the vacuum injection method from the end face at the time of electrolyte solution injection described below, it is not necessary to form the injection hole 22a of the electrolyte solution 14 and the air discharge hole 22b for performing air discharge at the time of injection. .

  A method of assembling the dye-sensitized photoelectric conversion element 200 will be described with reference to FIG.

  As shown in FIG. 13A, a sealing material 16 made of an ultraviolet curable resin or the like is applied along the peripheral edge of the second substrate 20 on which the porous semiconductor layer 12 is formed in the step of FIG. The first substrate 22 on which the catalyst layer 21 is formed in the step of FIG. 12 is positioned and overlapped.

  Next, the sealing material 16 is cured by irradiating ultraviolet rays or the like from the first substrate 22 side, and the second substrate 20 and the first substrate 22 are bonded together via the sealing material 16.

  Subsequently, as shown in FIG. 13B, the electrolytic solution 14 is injected from the injection hole 22 a formed in the first substrate 22. At this time, since the internal air escapes from the vent hole 22b, the electrolyte solution 14 can be injected smoothly.

  Next, although illustration is omitted, the injection hole 22a and the vent hole 22b are sealed by adhesion of a glass plate, filling with a resin, or the like so as to prevent the electrolyte solution 14 from leaking out.

  As a result, the dye-sensitized photoelectric conversion element 200 having the configuration shown in FIG. 13C is assembled.

[Second Embodiment]
(Dye-sensitized photoelectric conversion element with serial wiring structure)
Next, a configuration example of the dye-sensitized photoelectric conversion element 200a according to the second embodiment will be described with reference to FIGS.

  The dye-sensitized photoelectric conversion element 200a according to the second embodiment has a configuration in which two cells are arranged in series on one substrate.

As shown in FIG. 14, on the second substrate 20 composed of a glass substrate or a flexible plastic substrate, a transparent electrode 10 ₁ and 10 ₂ across a predetermined gap 10a.

Transparent electrodes 10 ₁ and 10 _2, for example, FTO, ZnO, ITO, is formed by sputtering or the like, such as SnO _2.

Figure 15 As shown in, on the transparent electrode 10 _2, pole between the wiring electrodes 3S between the substrates to the cathode electrode 3K and two cells as a negative electrode of the dye-sensitized photoelectric conversion element 200 and the series arrangement Is formed of, for example, Ag, Al, Cu, or the like.

As shown in FIG. 16, on the transparent electrode 10 ₁ and 10 ₂ are porous semiconductor layer 12 ₁ and 12 ₂ are respectively formed.

Incidentally, the porous semiconductor layer 12 ₁ and 12 ₂ can be formed by screen printing (see FIG. 11) such as shown in the manufacturing method of the dye-sensitized photoelectric conversion element 200 according to the first embodiment. That is, for example, a mask member having an opening corresponding to the porous semiconductor layer to be formed is aligned and set, a paste containing fine particles such as TiO ₂ is applied on the mask member, and the inside of the opening of the mask member is applied by a squeegee. To fill. Then, after removing the mask member, the porous semiconductor layer 12 ₁ and 12 ₂ are formed by firing a paste layer at a predetermined temperature. The step of adsorbing the dye on the porous semiconductor layer 12 ₁ and 12 ₂ is the same as in the case shown in FIG. 11 (c).

In addition, as shown in FIG. 17, first electrodes 18 ₁ and 18 ₂ are formed on a first substrate 22 made of a glass substrate, a flexible plastic substrate, or the like, with a predetermined interval 18a interposed therebetween. Catalyst layers 21 ₁ and 21 ₂ are formed on the electrodes 18 ₁ and 18 ₂ .

The first electrodes 18 ₁ and 18 ₂ are formed by, for example, sputtering film formation of FTO, ZnO, ITO, SnO ₂ or the like.

The catalyst layers 21 ₁ and 21 ₂ can be formed by screen printing (see FIG. 12) shown in the method for manufacturing the dye-sensitized photoelectric conversion element 200 according to the first embodiment. That is, a mask member having an opening corresponding to the catalyst layer to be formed is aligned and set on the first substrate 22 after the first electrodes 18 ₁ and 18 ₂ are formed, and activated carbon and TiO ₂ , A paste containing metal oxide fine particles such as ZnO and WO ₃ is applied onto the mask member, and the paste is filled into the opening of the mask member by a squeegee. Then, after removing the mask member, by firing a paste layer at a predetermined temperature, the catalyst layer 21 ₁ and 21 ₂ are formed.

Also, on the first electrode 18 _1, Ya pole between the wiring electrodes 3S for example Ag between the substrates for the anode electrode 3A and the two cells as the positive electrode of the dye-sensitized photoelectric conversion element 200 and the series arrangement It is formed of Al, Cu or the like.

  Then, as shown in FIG. 18, the second substrate 20 is bonded onto the first substrate 22 via the sealing material 16.

A schematic cross-sectional structure diagram of FIG. 19 is a dye-sensitized photoelectric conversion completed by injecting electrolytic solutions 14 ₁ and 14 ₂ into cells that are arranged in series via a sealing material 16 and bonded together as shown in FIG. The structure of the element 200a is shown.

  According to the dye-sensitized photoelectric conversion element 200a according to the second embodiment, it is possible to improve the power generation characteristics while reducing the manufacturing cost.

[Third embodiment]
(Manufacturing method of a plurality of dye-sensitized photoelectric conversion elements)
Next, another method for manufacturing the dye-sensitized photoelectric conversion element 200 according to the third embodiment will be described with reference to FIGS.

  In the method of manufacturing a dye-sensitized photoelectric conversion element according to the third embodiment, a plurality of (m × n: where m and n are integers) cells are formed and separated to form a plurality of dye-sensitized photoelectric conversion elements. This is a manufacturing method for obtaining the conversion element 200.

As shown in FIG. 20, on a second substrate 20 composed of a glass substrate, a flexible plastic substrate, or the like, a total of 10 ₁₁ to 10 _mn with a predetermined interval therebetween, where m and n are (Integer) transparent electrodes are formed.

The transparent electrodes 10 ₁₁ to 10 _mn are formed by, for example, sputtering film formation of FTO, ZnO, ITO, SnO ₂ or the like.

Although not shown, on the transparent electrode ₁₀ 11 _{to 10 mn} are porous semiconductor layer 12 are formed.

  The porous semiconductor layer 12 can be formed by applying screen printing (see FIG. 11) shown in the method for manufacturing the dye-sensitized photoelectric conversion element 200 according to the first embodiment. Further, a dye is adsorbed on each porous semiconductor layer 12.

In addition, as shown in FIG. 21, a total of _mxn of 18 ₁₁ to 18 _mn with a predetermined interval on the first substrate 22 composed of a glass substrate or a flexible plastic substrate or the like (where m and n n is an integer) first electrodes.

The first electrodes 18 ₁₁ to 18 _mn are formed, for example, by sputtering film formation of FTO, ZnO, ITO, SnO ₂ or the like.

Although not shown, on the first electrode ₁₈ 11 _{~ 18 mn,} the catalyst layer 21 are formed.

  The catalyst layer 21 can be formed by screen printing (see FIG. 12) shown in the method for manufacturing the dye-sensitized photoelectric conversion element 200 according to the first embodiment.

  Then, as shown in FIG. 22, a sealing material 16 made of an ultraviolet curable resin or the like is applied to each element on the first substrate 22, and the second substrate 20 is aligned with high accuracy. One substrate 22 is overlaid. Then, the sealing material 16 is cured by irradiation with ultraviolet rays or the like, and the first substrate 22 and the second substrate 20 are bonded to each other through the sealing material 16.

  FIG. 23 is a schematic cross-sectional structure diagram of the dye-sensitized photoelectric conversion element configured as described above, taken along line II of FIG.

  As shown in FIG. 23, only the substrate remains between the sealing materials 16, but this becomes a scribe line SL, which will be described later, and is separated into each element by a break such as hitting.

  Next, in a state where a total of m × n dye-sensitized photoelectric conversion elements are bonded as shown in FIG. 22, a horizontal scribe line SL1 is formed as shown in FIG.

  Specifically, each scribing line SL1 is formed by accurately aligning the scribing wheel of the scribing device at the position where the sealing material 16 is provided.

  Subsequently, a vertical scribe line SL2 is formed as shown in FIG.

  Then, when an impact is given along the scribe line SL1 and the scribe line SL2, etc., the glass material breaks along the scribe line SL1 and the scribe line SL2 and is separated into each element due to the wall opening property of the glass material.

  Although not shown in the figure, after separation into each element, an electrolyte solution is injected, sealed by glass plate adhesion or resin filling, etc., and treated so that the electrolyte solution does not leak out. A photoelectric conversion element is built in.

  According to the method for manufacturing the dye-sensitized photoelectric conversion element according to the third embodiment, the manufacturing cost of the dye-sensitized photoelectric conversion element 200 with improved power generation characteristics can be reduced.

  The time chart of FIG. 26 shows an example of temperature conditions (firing profile) when the catalyst layer 21 included in the dye-sensitized photoelectric conversion elements 200 and 200a according to the first to third embodiments is fired. In this example, the temperature is maintained at room temperature (RT) from the start of firing to t0, the temperature is increased to 450 ° C. with a temperature gradient of about 15 ° C./min at time t0 to t1 (for example, 30 minutes), and time t1 to t2 (for example, 30 minutes) at 450 ° C.

  Next, for a period of time t2 to t3 (for example, for 30 minutes K), the temperature is lowered to a room temperature (RT) with a temperature gradient of about −15 ° C./min, and the firing is finished.

FIG. 27 shows the operation principle of the dye-sensitized photoelectric conversion element 200 according to the first to third embodiments. Moreover, FIG.28 (b) is an enlarged view of the B section of FIG.

  When the following reactions (a) to (d) occur continuously, an electromotive force is generated, and a current is conducted to the load 24.

(A) The dye molecules in the porous semiconductor layer 12 absorb photons (hν), emit electrons (e ⁻ ), and the dye molecules become oxidants.

(B) The reduced redox electrolyte diffuses in the porous semiconductor layer 12 and approaches the oxidized dye molecules.

(C) Electrons (e ⁻ ) are supplied from the redox electrolyte to the dye molecules. The redox electrolyte becomes an oxidized redox electrolyte, and the dye molecule becomes a reduced dye molecule.

(D) The redox electrolyte diffuses in the direction of the first electrode 18 and is supplied with electrons by the catalytic action of the activated carbon AC of the catalyst layer 21 to become a redox electrolyte of the reductant.

  As a comparative example, as shown in FIG. 28A, Pt particles can be formed at a low cost when precipitation of platinum (Pt) by heat treatment is used.

(Experimental results on power generation characteristics)
29 to 31 show experimental results regarding the power generation characteristics of the dye-sensitized photoelectric conversion element 200 according to the first embodiment.

  FIG. 29 is a graph showing power generation characteristics when the dye-sensitized photoelectric conversion element 200 is irradiated with 200 lx white light. In the graph, C represents the power generation characteristics of the dye-sensitized photoelectric conversion element 200 according to the first embodiment, and Pt represents the power generation characteristics when the catalyst layer is made of platinum (Pt) as a comparison target ( The same applies to FIGS. 30 and 31).

  FIG. 30 is a graph showing power generation characteristics when the dye-sensitized photoelectric conversion element 200 is irradiated with 800 lx white light.

  FIG. 31 is a graph showing power generation characteristics when the dye-sensitized photoelectric conversion element 200 is irradiated with 50000 lx white light.

  As can be seen from the graphs of FIGS. 29 and 30, when 200 lx or 800 lx white light is irradiated, the dye-sensitized photoelectric conversion element 200 according to the first embodiment uses a platinum (Pt ).

  On the other hand, as shown in FIG. 31, when 50,000 lx of white light is irradiated, the dye-sensitized photoelectric conversion element 200 according to the first embodiment is more effective than the case where the catalyst layer is made of platinum (Pt). It can be seen that the power generation characteristics are superior.

As described above, the dye-sensitized photoelectric conversion element 200 according to the first embodiment is equivalent to or more than the case where the catalyst layer is formed of platinum (Pt), which has been conventionally considered to have excellent catalytic properties. Has power generation characteristics. Moreover, fine particles of activated carbon and metal oxides such as TiO ₂ , ZnO, SnO _{2, and} WO ₃ constituting the catalyst layer 21 of the dye-sensitized photoelectric conversion element 200 according to the first embodiment are made of platinum (Pt). It is relatively inexpensive, and there is no need to use a vacuum film formation method when forming a film of platinum (Pt), and the manufacturing cost is relatively inexpensive, and the price / performance ratio is platinum (Pt). It can be said that it greatly exceeds the case of formation.

[Other embodiments]
As described above, the embodiments have been described. However, it should be understood that the descriptions and drawings constituting a part of this disclosure are illustrative and do not limit the present invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.

  As described above, the present invention includes various embodiments not described herein.

(Electric double layer capacitor)
For example, in the electric double layer capacitor, any one of the active material electrodes 110 and 112 can be formed of a conductive thin film having fine particles of metal oxide having corrosion resistance against an electrolytic solution and one of activated carbon and organic matter.

(Lithium ion capacitor)
Further, for example, in a lithium ion capacitor, any of the active material electrodes 111 and 112 can be formed of a conductive thin film having fine particles of metal oxide having corrosion resistance to an electrolytic solution and one of activated carbon and organic matter.

(Lithium ion battery)
Further, for example, in a lithium ion battery, any of the active material electrodes 111 and 113 can be formed of a conductive thin film having fine particles of metal oxide having corrosion resistance to an electrolytic solution and one of activated carbon and organic matter.

  The dye-sensitized photoelectric conversion element of the present invention can generate electric power with incident light from a low-illuminance light source such as indoor light as well as sunlight. The present invention can be applied to various systems such as auxiliary power supplies for various electronic devices and drive power supplies for wireless communication sensor modules.

2 ... Semiconductor fine particles 3A ... Anode electrode 3K ... Cathode electrode 3S ... Interelectrode electrode 4 ... Dye molecule 10 ... Transparent electrode 12 ... Porous semiconductor layer 12a ... Paste 14 ... Charge transport layer (electrolyte)
DESCRIPTION OF SYMBOLS 16 ... Sealing material 18 ... 1st electrode 20 ... 2nd board | substrate 19, 21 ... Catalyst layer 21a ... Paste 22 ... 1st board | substrate (glass substrate)
22a ... Injection hole 22b ... Deaeration hole 23a, 23b ... Mask member 24 ... Load 25a, 25b ... Squeegee 26, 28 ... Redox electrolyte 30, 32 ... Dye molecule 44 ... Container 45 ... Dye solution 100 ... Working electrode 110, 112, 113 ... Active material electrode 130 ... Separator 132a, 132b ... Lead electrode 200, 200a ... Dye-sensitized photoelectric conversion element

Claims (8)

A first substrate;
A first electrode disposed on the first substrate;
A catalyst layer formed on the first electrode and having catalytic activity for a redox electrolyte;
An electrolyte solution in contact with the catalyst layer and dissolving the redox electrolyte in a solvent;
A porous semiconductor layer in contact with the electrolyte solution, comprising semiconductor fine particles and dye molecules;
A second electrode disposed in the porous semiconductor layer;
A second substrate disposed on the second electrode;
A sealing material disposed between the first substrate and the second substrate and sealing the electrolyte;
The dye-sensitized photoelectric conversion element, wherein the catalyst layer is composed of a conductive thin film having one of metal oxide fine particles having corrosion resistance to the activated carbon and the electrolytic solution or an organic material having conductivity.   2. The dye-sensitized photoelectric conversion element according to claim 1, wherein the catalyst layer is formed by firing a paste layer containing metal oxide fine particles having corrosion resistance to the activated carbon and the electrolyte solution. _3. The dye-sensitized photoelectric conversion element according to claim 1, wherein the metal oxide having corrosion resistance to the electrolytic solution is TiO ₂ , ZnO, SnO _2, or WO ₃ . Forming a first electrode on a first substrate;
Forming a conductive thin film having, as a catalyst layer on the first electrode, fine particles of activated carbon and metal oxide having corrosion resistance to an electrolyte or an organic material having conductivity;
Forming a second electrode on the second substrate;
Forming a porous semiconductor layer comprising semiconductor fine particles on the second electrode;
Immersing the porous semiconductor layer in a dye solution to adsorb dye molecules;
The counter electrode substrate in which the first electrode and the catalyst layer are formed on the first substrate, and the porous semiconductor layer in which the second electrode and the dye molecules are adsorbed are formed on the second substrate. The polar substrate,
A step of bonding via an inter-electrode electrode between the substrates to be arranged in series and a sealing material,
And a step of injecting an electrolytic solution between the counter electrode substrate and the working electrode substrate. Forming a plurality of first electrodes at a predetermined interval on the first substrate;
Forming a conductive thin film having one of activated carbon and metal oxide fine particles having corrosion resistance against an electrolytic solution or an organic material having conductivity as a catalyst layer on each first electrode;
Forming a plurality of second electrodes opposed to the first electrodes on a second substrate;
Forming a porous semiconductor layer comprising semiconductor fine particles on each of the second electrodes;
Adsorbing dye molecules to each of the porous semiconductor layers;
A counter electrode substrate having a plurality of the first electrodes and the catalyst layer formed on the first substrate; a plurality of the second electrodes and the porous semiconductor layer having the dye molecules adsorbed on the second substrate; And a step of bonding the working electrode substrate formed through a sealing material so as to partition a cell that becomes a dye-sensitized photoelectric conversion element,
A scribe step for forming a scribe line on each of the first substrate or the second substrate for separating each cell to be a dye-sensitized photoelectric conversion element;
A separation step of breaking along the scribe line and separating;
And a step of injecting an electrolytic solution into each cell of the separated dye-sensitized photoelectric conversion element.   The step of forming the conductive thin film includes a step of applying a paste containing fine particles of metal oxide having corrosion resistance to the activated carbon and an electrolytic solution on the first electrode of the first substrate. 6. A method for producing a dye-sensitized photoelectric conversion element according to 5. The step of applying the paste on the first electrode of the first substrate includes:
Aligning and overlaying a mask having an opening of a predetermined area on the first electrode;
Depositing the paste on the mask;
Filling the opening with the paste with a squeegee;
Removing the mask;
And baking the paste layer composed of the paste at a predetermined baking temperature.   The said baking temperature is 400-450 degreeC, The manufacturing method of the dye-sensitized photoelectric conversion element of Claim 7 characterized by the above-mentioned.

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