JP2010205581A - Manufacturing method of photoelectric conversion element using conductive mesh - Google Patents

Abstract

The present invention provides a method for manufacturing a photoelectric conversion element that can improve the conductivity of an electrode and that can shorten the distance between both electrodes, has a low resistance between both electrodes, and has high photoelectric conversion efficiency.
An electrode (10) having a transparent conductive member on a transparent substrate (6) and a photocatalytic film (8) thereon, and a counter electrode (9) having at least a conductive member on a counter substrate (1) are predetermined. This is a method for producing a photoelectric conversion element, which is arranged in an opposing manner at intervals and in which an electrolyte is arranged between both electrodes. A conductive mesh (2) is provided as a transparent conductive member on the surface of the transparent substrate (6), a glassy film (4) is formed thereon and the conductive mesh (2) is embedded, and the glassy film (4) The upper surface of the conductive mesh (2) is exposed from the glassy film (4) by grinding the surface portion, and the photocatalytic film (8) is provided thereon.

[Selection] Figure 4

Description

  In the present invention, an electrode having a transparent conductive film and a photocatalyst film thereon on a transparent substrate and a counter electrode having at least a conductive member on the counter electrode substrate are arranged at a predetermined interval and an electrolyte is arranged between the electrodes. The present invention relates to a method for producing a photoelectric conversion element comprising a conductive mesh on a transparent substrate.

  In general, a photoelectric conversion element such as a dye-sensitized solar cell is formed by forming a transparent conductive film on a transparent substrate such as a glass plate and forming a photocatalytic film made of a metal oxide such as titanium oxide on the transparent conductive film. An electrode formed by adsorbing a film with a photosensitizing dye such as a ruthenium complex and a counter electrode formed by forming a transparent conductive film on a counter electrode substrate are arranged opposite to each other, and an iodine electrolyte or the like is formed between the electrodes. One having an electrolyte layer interposed is known (Patent Document 1).

  In the photoelectric conversion element, since the resistance value of the electrode has a great influence on the photoelectric conversion efficiency, a metal mesh is provided on the electrode to reduce the resistance between the two electrodes and increase the conductivity (patent) Reference 2).

  By providing a conductive mesh on the electrode of the photoelectric conversion element as described above, the conductivity of the electrode can be increased. However, with such a configuration, the distance between the two electrodes is inevitably increased due to the thickness of the conductive mesh, and the resistance between the two electrodes is increased, so that electrons cannot reach the substrate surface, and the electron transfer efficiency There was a problem that decreased.

  In order to solve this problem, it is conceivable to reduce the thickness of the conductive mesh, but in this case, it is difficult to make the thickness of the metal mesh on the electrode constant, and this prevents contact between the two electrodes. Again, it is necessary to increase the distance between the two electrodes, and the same problem as above cannot be avoided.

  Therefore, the present invention provides a method for producing a photoelectric conversion element that can improve the conductivity of the electrodes and can shorten the distance between the two electrodes, and has low resistance between the two electrodes and high photoelectric conversion efficiency.

In the invention according to claim 1, a transparent conductive member on the transparent substrate, an electrode having a photocatalytic film thereon, and a counter electrode having at least a conductive member on the counter electrode substrate are arranged at a predetermined interval so as to face each other. A method for producing a photoelectric conversion element in which an electrolyte is disposed on the substrate,
A conductive mesh is provided as a transparent conductive member on the surface of the transparent substrate, a glassy film is formed thereon, the conductive mesh is embedded, the surface of the glassy film is ground, and the upper end of the conductive mesh is glass. It is exposed from a film-like film, and the photocatalyst film is provided thereon.

 The invention according to claim 2 further includes providing a conductive mesh as a conductive member on the surface of the counter electrode substrate, forming a glassy film thereon, embedding the conductive mesh, and grinding the surface portion of the glassy film. 2. The method for producing a photoelectric conversion element according to claim 1, wherein an upper end portion of the conductive mesh is exposed from the glassy film.

 The invention according to claim 3 is characterized in that the conductive mesh is made of a material that functions as a catalyst for the reaction of reducing the oxidant of the redox couple in the electrolyte to the reductant. It is a manufacturing method of this photoelectric conversion element.

 The invention according to claim 4 is characterized in that a layer made of a material functioning as a catalyst for the reaction of reducing the oxidized form of the redox couple in the electrolyte to a reduced form is formed on the exposed surface of the conductive mesh. It is a manufacturing method of the photoelectric conversion element of Claim 2.

  According to the first aspect of the present invention, the electrode can obtain sufficient conductivity and the distance between the two electrodes can be reduced, so that the resistance between the two electrodes can be lowered.

  According to the second aspect of the invention, the counter electrode can also have sufficient conductivity and the distance between the two electrodes can be further reduced, so that the resistance between the two electrodes can be further reduced.

  According to the invention of claim 3 or 4, the above effect can be further increased.

  In this way, a photoelectric conversion element with high photoelectric conversion efficiency can be manufactured.

3 is a vertical longitudinal sectional view schematically showing a counter electrode of Example 1. FIG. 2 is a plan view showing a conductive mesh of Example 1. FIG. 2 is a vertical longitudinal sectional view schematically showing the arrangement of electrodes and counter electrodes in Example 1. FIG. 5 is a vertical longitudinal sectional view showing a photoelectric conversion element of Reference Example 1. FIG.

  First, the invention according to claim 1 will be described. In this invention, a conductive mesh is provided as a transparent conductive member on the surface of the transparent substrate, a glassy film is formed thereon, the conductive mesh is embedded, and the surface portion of the glassy film is ground to form a conductive mesh. The upper end portion is exposed from the glassy film, and the photocatalytic film is provided thereon.

  As the transparent substrate, a synthetic resin plate, a glass plate or the like is used as appropriate, but a thermoplastic resin film such as a PEN (polyethylene naphthalate) film is preferable. In addition to PEN, the synthetic resin may be polyethylene terephthalate, polyester, polycarbonate, polyolefin, or the like.

  The thickness of the transparent substrate is preferably several tens of μm to 1 mm.

  Examples of the conductive mesh material include metals such as iron, nickel, chromium, titanium, aluminum, platinum, silver, palladium, cobalt, copper, copper, tantalum, ruthenium, tungsten, zinc, tin, and alloys thereof. However, the present invention is not limited thereto, and any conductive polymer fiber, metal-coated polymer fiber, natural fiber, or the like having conductivity can be used.

  As a method of providing a conductive mesh on the surface of the transparent substrate, in addition to the known roll-to-roll method, when using a synthetic resin plate for the transparent substrate, the conductive mesh is heated by energization or directly heated while the transparent substrate is used. A method of embedding a heated conductive mesh is preferred.

  In addition, a conductive mesh is arranged on a transparent substrate, and a liquid transparent resin (for example, polyvinyl alcohol), liquid transparent rubber (for example, styrene butadiene rubber) or the like is poured on the conductive mesh, or about 0.5 to 1 mm. A method of applying the thickness by a squeegee method, drying, and lightly polishing the surface is preferable. The liquid transparent resin or rubber layer may be formed on a transparent substrate by a squeegee method or the like, and a conductive mesh may be embedded on the layer.

  Although the conductive mesh is embedded in the transparent substrate by the above method, the conductive mesh preferably exposes about 1/3 to 1/2 of the thickness of the conductive mesh on the transparent substrate surface.

  The diameter (mesh thickness) of the wire material (wire) constituting the conductive mesh is 500 μm or less, and the distance between the wire materials (wires) is 100 μm or less. The shorter one is preferable, but the aperture ratio is 80% or more. It is preferable to do.

  The shape of the opening area of the conductive mesh is not particularly limited, but it can be square, rectangular, rhombus, parallelogram, trapezoid, triangle, circle, ellipse, polygon, irregular shape, etc. It is determined as appropriate in consideration.

  A preferable conductive mesh is, for example, an expanded mesh made of titanium having a thickness of 50 μm or less.

  The glassy film formed on the surface of the transparent substrate after providing the conductive mesh acts as a sealing material for holding the conductive mesh and preventing moisture and the like from entering from the outside of the photoelectric conversion element. By scattering the light beam, the light beam is confined in the element, which contributes to improving the photoelectric conversion efficiency.

  The glassy film can be obtained by applying a coating solution containing silicate, alumina silicate, or the like on the upper surface of a transparent substrate in which a conductive mesh is embedded and baking it. Next, the surface of the transparent substrate on which the conductive mesh and the glassy film are formed is ground by, for example, a normal lapping or polishing method to expose and smooth the upper end portion of the conductive mesh. The thickness of the glassy film is preferably 1 sub μm to 20 μm.

  Further, in the electrode, in order to improve the conductivity and prevent the conductive mesh from being corroded by the electrolyte, it is preferable to improve the corrosion resistance by forming a transparent conductive film over the exposed mesh surface and the glassy film surface.

There are various methods for forming this film, such as ionized vapor deposition and CVD, and it is not particularly limited. As a metal target in the sputtering method, tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), tin oxide (SnO ₂ ), indium zinc oxide (IZO), and zinc oxide (ZnO) of a transparent conductive film are used. Materials such as In—Sn alloy, Zn, In—Zn alloy, Sn, Ga—Zn alloy, Al—Zn alloy, etc. are preferably used. There is no particular limitation. The thickness of the transparent conductive film is preferably several tens to several hundreds nm.

  A photocatalytic film is formed on the conductive mesh of the electrode or the transparent conductive film thereon. For example, i) a method in which a paste containing photocatalyst particles (metal oxide particles) is applied on a conductive mesh or a transparent conductive film thereon, dried, and optionally fired, or ii) a metal oxide The sol is electrostatically applied onto a conductive mesh or a transparent conductive film thereon, dried, and optionally fired.

The photocatalytic particles are made of a metal oxide such as titanium oxide (TiO ₂ ), tin oxide (SnO ₂ ), tungsten oxide (WO ₃ ), zinc oxide (ZnO), or niobium oxide (Nb ₂ O ₅ ). Furthermore, it is preferable to mix photocatalyst particles having a particle size of several hundred nm.

  In the method i), the photocatalyst-containing paste may be one obtained by adding photocatalyst particles to pure water, ethanol, propanol, t-butanol or the like.

In the method ii), the electrostatic coating apparatus is set on the negative side, the conductive mesh as the object to be coated or the transparent conductive film thereon is set on the positive side, a high voltage is applied therebetween to form an electrostatic field, and electrostatic coating is performed. The metal oxide sol sprayed from the spray nozzle of the apparatus is charged to the negative side and applied to the conductive mesh or the surface of the transparent conductive film thereon. In this case, laser irradiation may be performed while electrostatic coating, and the drying and baking may be performed simultaneously. The electrostatic coating apparatus is not limited to the above configuration as long as it can apply the metal oxide sol onto the conductive mesh or the transparent conductive film thereon. The laser is preferably visible light region to near infrared region (700 nm to 1100 nm), specifically, Nd: YAG laser (1064 nm), Nd: YVO4 laser (1064 nm), or TI: sapphire laser (650-1100 nm), A tunable laser such as a Cr: LiSAF laser (780-1010 nm), an alexandrite laser (700-820 nm), or a CO ₂ laser is applicable.

  Examples of the metal compound used as a starting material for the metal oxide sol include metal alkoxides, metal acetylacetonates, metal carboxylates, and metal inorganic compounds such as metal nitrates, oxychlorides, and chlorides. Can be mentioned.

  The metal oxide is preferably titanium oxide, and other examples include tin oxide, tungsten oxide, zinc oxide, and niobium oxide.

  As an example of using titanium oxide, as metal alkoxide, titanium tetramethoxide, titanium ethoxide, titanium isopropoxide, titanium butoxide, etc., as metal acetylacetonate, as titanium acetylacetonate, as metal carboxylate , Titanium carboxylate, titanium nitrate, titanium oxychloride, titanium tetrachloride and the like.

  Furthermore, the above metal compounds include water, methanol, ethanol, 1-propanol, isopropyl alcohol, 1-butanol, 2-butanol, isobutanol, t-butanol, 1-pentanol, 2-pentanol, 3-pentanol and the like. By adding a solvent, acid or ammonia, and other additives, sol-formation and gelation are performed.

  In the methods i) and ii), the drying is performed at room temperature for about 5 to 30 minutes. Firing is performed at a temperature of 450 to 550 ° C. for about 30 to 60 minutes.

  The thickness of the photocatalyst film is preferably 5 to 20 μm.

  Next, it is preferable to irradiate the photocatalyst film with a laser from the transparent substrate side through the same electrode. This laser may be the same as described above.

  Thereafter, the photosensitizing dye is adsorbed on the photocatalyst film. The photosensitizing dye is adsorbed by, for example, immersing an electrode having a photocatalytic film in an immersion liquid containing the photosensitizing dye and adsorbing the dye on the surface of the photocatalytic film. After immersion, it is preferable to perform drying and further firing. Photosensitizing dyes include, for example, ruthenium complexes and iron complexes having a ligand containing a bipyridine structure, a terpyridine structure, etc., porphyrin-based and phthalocyanine-based metal complexes, and organic dyes such as eosin, rhodamine, merocyanine, and coumarin. It may be.

  Next, the invention according to claim 2 will be described. In the present invention, a conductive mesh is further provided as a conductive member on the surface of the counter electrode substrate, a glassy film is formed thereon, the conductive mesh is embedded, and the surface of the glassy film is ground to form a conductive mesh. The upper end of is exposed from the glassy film.

  The material of the counter electrode substrate may be the same as that of the transparent substrate. The thickness of the counter electrode substrate is preferably several tens of μm to 1 mm.

  A method of providing a conductive mesh on the surface of the counter electrode substrate, a method of embedding a conductive mesh by forming a glassy film on the surface, and a glass-like upper surface of the conductive mesh by grinding the surface of the glassy film. The method of exposing from the film may be the same as the method described in the invention of claim 1.

  The glassy film formed here has an effect of preventing corrosion of the counter electrode substrate and the conductive mesh due to an electrolyte such as iodine, in addition to the effect of the electrode.

  As the material for the conductive mesh provided on the counter electrode, in addition to the above materials, a material that functions as a catalyst for the reaction of reducing the oxidized form of the redox couple in the electrolyte to a reduced form is preferable. , Titanium, polyethylenedioxythiophene (PEDOT), platinum, and a mixture of titanium and carbon carrying chloroplatinic acid or platinum.

  Further, on the exposed surface of the conductive mesh, if necessary, a coating solution of a material that functions as a catalyst for a reduction reaction that reduces the oxidized form of the redox couple in the electrolyte to a reduced form is applied, and further fired. To do. Examples of such a material include titanium, polyethylene dioxythiophene (PEDOT), platinum, and a mixture of titanium and carbon carrying chloroplatinic acid or platinum. Although baking after application | coating is not specifically limited, The method by a laser is preferable. This laser may be the same as described above. Thereby, the said reduction reaction in the exposed surface of an electroconductive mesh is accelerated | stimulated (catalyst capability improvement), and it leads to the improvement of corrosion resistance.

  If it is not necessary to introduce light mainly into the device on the electrode side and light into the device on the counter electrode side, the counter electrode substrate does not need to be transparent, and the conductive mesh of the counter electrode has an open area (transmittance). ) Or a conductive plate having no opening may be used on the counter electrode side to improve conductivity. In addition, a coating liquid in which a conductive polymer such as polyethylenedioxythiophene (PEDOT) / polysilastyrene (PSS) and ethanol are mixed in a suitable ratio (for example, 1: 1) is spinned in the opening area of the conductive mesh. A layer for improving conductivity may be formed by applying by a method such as coating, drying, and baking as necessary.

  In the photoelectric conversion element, a transparent conductive member on a transparent substrate, an electrode having a photocatalyst film thereon, and a counter electrode having at least a conductive member on a counter electrode substrate are arranged in an opposing manner at a predetermined interval, and an electrolyte is interposed between both electrodes. It is mainly configured by being arranged.

As the electrolyte, for example, an iodine-based electrolyte is used. Specifically, an electrolyte component such as iodine, iodide ion, or tertiary butyl pyridine is dissolved in an organic solvent such as ethylene carbonate or methoxyacetonitrile. Is exemplified. The electrolyte is not limited to an electrolyte and may be a solid electrolyte. The solid electrolyte, for example, is illustrated DMPImI (dimethylpropyl imidazolium iodide) is, in addition, LiI, NaI, KI, CsI, metal iodide such as CaI _2, and tetraalkylammonium iodide and quaternary ammonium compounds A combination of iodides such as the iodine salts of I ₂ and I ₂ ; bromides such as bromides of metal bromides such as LiBr, NaBr, KBr, CsBr, CaBr ₂ and quaternary ammonium compounds such as tetraalkylammonium bromide and Br _2. And the like can be used as appropriate.

  In the photoelectric conversion element, for example, a transparent conductive member for electrodes, a conductive member for counter electrodes, a collecting electrode, an electrolyte layer, and a photocatalyst film are arranged at predetermined intervals between a transparent electrode substrate and a rectangular counter electrode substrate. In this case, the connection between the electrode and the counter electrode may be in series or in parallel. In either case, the electrolyte layer and the photocatalyst film are separated from each other by the sealing material. In the case of series connection, a transparent conductive member for electrodes, a conductive member for counter electrode, and a collecting electrode are formed with a gap between adjacent ones, and the transparent conductive member for electrode and the conductive member for counter electrode are connected by a conductor. Is done. In the case of parallel connection, the electrode transparent conductive member, the counter electrode conductive member, and the current collecting electrode have a shape with no gap between adjacent ones.

  If the transparent substrate is not embedded with conductive mesh, a transparent conductive film is formed on the transparent substrate (ITO glass, FTO glass, etc.), metal plate or metal foil (aluminum, copper, tin, titanium, etc.) Etc. can be used.

  In addition, when the counter electrode substrate is not embedded with a conductive mesh, the counter electrode is formed by forming a transparent conductive film on the counter electrode substrate, or a conductive film such as platinum or PEDOT on the surface of a metal sheet such as aluminum, copper or tin. May be formed.

  In order to assemble the photoelectric conversion element, for example, the electrode and the counter electrode are aligned to face each other at an interval of several μm to several tens of μm, and the both electrodes are sealed with a heat-sealing film or a sealing material, and the counter electrode or The electrolyte is injected from holes or gaps provided in advance in the electrodes. When a solid electrolyte is used, the photocatalyst film and the electrolyte layer may be stacked so as to be sandwiched between the two electrodes, and the peripheral portions thereof may be heat bonded. Heating may be performed by a mold, or may be performed by irradiation with an energy beam such as plasma (having a long wavelength), microwave, visible light (600 nm or more), or infrared light.

  Next, in order to describe the present invention specifically, examples of the present invention will be given.

Example 1 (Production of electrode and counter electrode)
In FIG. 1, a titanium expanded mesh (2) having an opening diameter of 100 μm and a thickness of 30 μm shown in FIG. 2 is heated on the upper surface of a counter electrode substrate (1) made of transparent biaxially stretched PET by energization. It was embedded so as to protrude 10 μm from the surface of the substrate.

  On the surface of the counter electrode substrate (1) embedded with the mesh (2), a coating liquid containing silicate was sprayed and dried to form a glassy film (4) having a thickness of 15 μm.

  Next, the surface of the counter electrode substrate (1) having the mesh (2) and the glassy film (4) is ground by lapping so that the upper end of the mesh (2) is exposed from the glassy film (4). The surface of (1) was smoothed.

  A 1-propanol solution containing 0.1% of chloroplatinic acid is applied on the counter electrode substrate (1) having the mesh exposed surface, dried, and then fired with a laser to have a thickness of 5 nm on the mesh exposed surface. A catalyst layer (5) was formed. Thus, the counter electrode (9) was constructed.

  On the other hand, in FIG. 3, after the titanium expanded mesh (2) is embedded in the upper surface of the transparent substrate (6) for electrodes made of transparent biaxially stretched PET by the same operation as described above, a glassy film is formed on the surface. (4) was formed.

  Then, by the same operation as described above, the surface of the transparent substrate (6) having the mesh (2) and the glassy film (4) is ground to expose the upper end of the mesh (2) from the glassy film (4). It was.

  A transparent conductive film (7) having a thickness of 150 nm made of tin-added indium oxide (ITO) is formed over the mesh exposed surface thus obtained and the surface of the glassy film (4), and further, photocatalyst particles are further formed thereon. Apply a paste containing titanium oxide particles (ethanol and water added with titanium oxide), dry at room temperature for 15 minutes, baked at 150 ° C for 15 minutes, on the transparent conductive film (7) A photocatalytic film (8) having a thickness of 10 μm was formed.

  An electrode (10) composed of a transparent substrate (6), a mesh (2), a glassy film (4), a transparent conductive film (7), and a photocatalytic film (8) is immersed in an immersion liquid (ruthenium complex ( N719, molecular weight 1187.7 g./mol) is dissolved in t-butanol: acetonitrile (volume ratio 1: 1), and the photocatalyst film (8) is immersed in a dye concentration: 0.3 mM for 40 minutes at a temperature of 40 ° C. The same dye was adsorbed on the surface.

  The transmittances of the counter electrode (9) and the electrode (10) were 85% and 5Ω / □.

  As shown in FIG. 3, the counter electrode (9) and the electrode (10) were arranged so as to face each other at an interval of 15 μm with each mesh (2) inside.

Example 2 (Manufacture of photoelectric conversion elements)
FIG. 4 shows an example of a photoelectric conversion element. The photoelectric conversion element is mainly composed of an electrode (10), a counter electrode (9) disposed so as to face the electrode (10), and an electrolyte (11) made of iodine disposed between both electrodes. The configurations of the electrode (10) and the counter electrode (9) are as described in the first embodiment with reference to FIGS.

  In FIG. 4, (1) is a counter electrode substrate, (2) is a titanium expanded mesh, (4) is a glassy film, (5) is a conductivity improving layer, (6) is a transparent substrate, and (7) is a transparent conductive material. (8) is a photocatalyst film, (9) is a counter electrode, (10) is an electrode, (11) is an electrolyte, and (12) is a plurality of sealing materials / separators provided between both electrodes. A plurality of sections are formed between them. (13) is a plurality of electrode between electrodes passed to both electrodes, and (14) is a sealing material for electrode protection.

When a 100 mm square dye-sensitized solar cell having the above-described configuration was prepared and the power conversion efficiency was measured by irradiation with a standard light source of AM 1.5 and 100 mW / cm ² , a high efficiency of conversion efficiency η = 6% was obtained. It was.

(1) is the counter electrode substrate
(2) is titanium expanded mesh
(3) is a glassy membrane
(5) is the conductivity enhancement layer
(6) is transparent substrate
(7) is transparent conductive film
(8) is a photocatalytic film
(9) is the counter electrode
(10) is an electrode
(11) is the electrolyte
(12) is a sealant and separator
(13) is the electrode between electrodes
(14) is a seal material for electrode protection

JP 2002-93475 A JP 2007-294288 A

Claims (4)

A photoelectric device comprising a transparent conductive member on a transparent substrate, an electrode having a photocatalyst film thereon, and a counter electrode having at least a conductive member on a counter electrode substrate arranged at a predetermined interval and facing each other, and an electrolyte disposed between the electrodes. A method for manufacturing a conversion element, comprising:
A conductive mesh is provided as a transparent conductive member on the surface of the transparent substrate, a glassy film is formed thereon, the conductive mesh is embedded, the surface of the glassy film is ground, and the upper end of the conductive mesh is glass. A method for producing a photoelectric conversion element, wherein the photocatalyst film is provided on the exposed film.   Furthermore, a conductive mesh is provided as a conductive member on the surface of the counter electrode substrate, a glassy film is formed on the conductive mesh, the conductive mesh is embedded, and the upper surface of the conductive mesh is ground by grinding the surface of the glassy film. 2. The method for producing a photoelectric conversion element according to claim 1, wherein the photoelectric conversion element is exposed from the glassy film.   3. The method of manufacturing a photoelectric conversion element according to claim 2, wherein the conductive mesh is made of a material that functions as a catalyst for a reaction for reducing an oxidized form of an oxidation-reduction pair in the electrolyte to a reduced form.   3. The photoelectric conversion layer according to claim 2, wherein a layer made of a material that functions as a catalyst for a reaction of reducing an oxidized form of the redox couple in the electrolyte to a reduced form is formed on the exposed surface of the conductive mesh. A method for manufacturing a conversion element.

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