KR102090978B1 - Dye-sensitized solar cell porous film and dye-sensitized solar cell - Google Patents

Abstract

A porous film containing titanium oxide formed on a film substrate, having a critical load of 8 mN or more, or Japanese Industrial Standard JIS K5600-5-4 "Paint General Test Method-Part 5: Mechanical Properties of Coating Film-Section 4: Scratching Hardness (pencil method) ”A porous film for a dye-sensitized solar cell, characterized in that the pencil hardness conforms to H or higher.

Description

Porous film for dye-sensitized solar cell and dye-sensitized solar cell {DYE-SENSITIZED SOLAR CELL POROUS FILM AND DYE-SENSITIZED SOLAR CELL}

The present invention relates to a porous membrane for a dye-sensitized solar cell and a dye-sensitized solar cell.

A porous film containing an oxide semiconductor such as titanium oxide, to which a photosensitive dye such as a ruthenium metal complex is adsorbed, is used for the photoelectrode of the dye-sensitized solar cell (DSC) (for example, see Patent Document 1). Conventionally, as a method for forming a porous film, for example, a method of forming a porous film by applying a slurry or paste containing particles of an oxide semiconductor onto a substrate and firing it at a high temperature of 400 ° C. or higher is exemplified.

Since the method for forming this porous film is fired at a high temperature, not only does it require a substrate having heat resistance, but also has a problem of high manufacturing energy.

As a method for forming a porous film, a slurry containing metal oxide fine particles and a dispersion medium is injected into a substrate together with a high-speed frame from a spray nozzle of a high-speed frame spraying device that burns by mixing fuel, oxygen and air, and deposits a metal oxide on the substrate The method of doing this can also be mentioned (for example, refer patent document 2).

Since the method of forming the porous film burns the titanium oxide particles, there is a problem that the thermal history remains in the titanium oxide particles, and the titanium oxide particles are deteriorated, resulting in low photoelectric conversion efficiency.

Further, as a method of forming the porous film, there is also a method of forming a porous film by applying a slurry or paste containing particles of an oxide semiconductor on a substrate and baking it at a low temperature such that a plastic substrate can be used. For example, see Patent Document 3).

The method of forming the porous film has a problem in that the slurry or paste is fired at a relatively low temperature, and thus the adhesion of the porous film to the substrate is low, and the porous film is easily peeled from the substrate.

In addition, as a method for forming a porous film, a slurry or paste containing particles of oxide semiconductor is coated on a heat-resistant substrate, and this is fired at a high temperature to form a porous film, followed by transfer adhesion of the porous film formed on the target substrate, Then, the method of forming a porous film on a base material by peeling a heat resistant base material is also mentioned (for example, refer patent document 4).

The method of forming this porous film has a problem that the manufacturing cost is high because the manufacturing process is complicated.

As a method for forming a porous film, a metal foil is used as a substrate having a high heat resistance temperature, a slurry or paste containing particles of oxide semiconductor is coated on the metal foil, and a method of forming a porous film by firing it at high temperature is also mentioned. There is (for example, see patent document 5).

The method of forming this porous film has a problem that, since the slurry or paste is fired at a high temperature, not only is the production energy high, but the price of the substrate having a high heat resistance temperature is high.

Japanese Patent No. 3435459 Japanese Patent Publication No. 2007-265648 Japanese Patent No. 462467 Japanese Patent Publication No. 2008-243425 Japanese Patent Publication No. 2006-286534

The present invention has been made in view of the above circumstances, and is provided with a porous film containing titanium oxide formed on a film substrate, and the porous film is a dye-sensitized type that exhibits the same degree of adhesion as a film formed with a high-temperature baking paste on a glass substrate. It is an object to provide a porous membrane for solar cells and a dye-sensitized solar cell.

(1) The porous membrane for dye-sensitized solar cells of the present invention is a porous membrane containing titanium oxide formed on a film substrate, having a critical load of 8 mN or more, or Japanese Industrial Standard JIS K5600-5-4 "Paint General Test Method- Part 5: Mechanical properties of the coated film-Chapter 4: Scratch hardness (pencil method).

(2) In the above (1), the porous film is formed by a non-heating process, and the non-heating process deposits the fine particles of the porous film onto the film substrate to form a porous film containing the fine particles. It may be a method.

(3) In the above (1) or (2), the non-heating process may be performed at room temperature.

(4) In any one of (1) to (3) above, the film thickness of the porous membrane for dye-sensitized solar cells is 8 to 12 μm, and the variation in film thickness may be ± 1 μm.

(5) In any one of (1) to (4) above, the porosity of the porous membrane may be 15 to 50%.

(6) The porous film according to any one of (1) to (5), wherein the porous film is formed by a non-heating process, and the non-heating process sprays the raw material fine particles of the porous film onto the film substrate, thereby discharging the raw material fine particles. It is a film-forming method for forming a porous film, and the raw material fine particles may be mixed particles of large-diameter particles having an average particle diameter of 0.2 to 2 µm and small-diameter particles having an average particle diameter of less than 1 to 200 nm.

(7) In the above (6), the mixing ratio of the large-diameter particles and the small-diameter particles may be 99.9 parts by weight: 0.1 parts by weight to 70 parts by weight: 30 parts by weight.

(8) In any one of (1) to (7) above, the glass transition temperature (Tg) of the film substrate may be less than 200 ° C.

(9) The dye-sensitized solar cell of the present invention includes a pair of opposing substrates, a pair of electrode films disposed opposite to each other, and a photoelectric conversion layer and an electrolyte layer formed between the electrode films. As one dye-sensitized solar cell, the photoelectric conversion layer is characterized by comprising the porous membrane for a dye-sensitized solar cell according to any one of the above (1) to (8).

(10) In the method for producing a porous membrane for a dye-sensitized solar cell of the present invention, a critical load is 8 mN or more on a film substrate by a non-heating process in which raw material fine particles are sprayed onto a film substrate, or Japanese Industrial Standard JIS K5600- It is characterized by forming a porous film having a pencil hardness of H or more in accordance with 5-4 "General Test Methods for Paints-Part 5: Mechanical Properties of Painted Films-Section 4: Scratching Hardness (Pencil Method)".

The porous membrane for dye-sensitized solar cells of the present invention is a porous membrane containing titanium oxide formed on a film substrate, having a critical load of 8 mN or more, or Japanese Industrial Standard JIS K5600-5-4 "Paint General Test Method-Part 5 : Mechanical properties of the coating film-Section 4: Scratching hardness (pencil method) Since the pencil hardness is greater than or equal to H, it can exhibit the same degree of adhesion as a film formed of a high-temperature baking paste on a glass substrate. Further, the dye-sensitized solar cell using the porous membrane for a dye-sensitized solar cell of the present invention is excellent in photoelectric conversion efficiency.

1 is a schematic cross-sectional view showing a porous membrane for a dye-sensitized solar cell as a first embodiment of the present invention.
Fig. 2 is a schematic configuration diagram showing an example of a film forming apparatus used in the present invention.
3 is a schematic cross-sectional view showing a dye-sensitized solar cell as a second embodiment of the present invention.
4 is a schematic cross-sectional view showing a part of a substrate forming process of a method for manufacturing a dye-sensitized solar cell shown as a second embodiment of the present invention.
5 is a schematic cross-sectional view showing a part of a substrate forming process of a method for manufacturing a dye-sensitized solar cell shown as a second embodiment of the present invention.
6 is a schematic cross-sectional view showing a part of a substrate bonding process of a method for manufacturing a dye-sensitized solar cell shown as a second embodiment of the present invention.

As an embodiment of the present invention, a porous membrane for a dye-sensitized solar cell and a dye-sensitized solar cell will be described.

In addition, this embodiment is demonstrated concretely in order to understand the meaning of invention better, and unless otherwise specified, this invention is not limited.

(Porous membrane for dye-sensitized solar cells)

1 is a schematic cross-sectional view showing a porous membrane for a dye-sensitized solar cell as a first embodiment of the present invention.

The porous film for dye-sensitized solar cell of the present embodiment (hereinafter, sometimes referred to as "porous film" in some cases) 10 is a transparent electrode film 12 formed on one side 11a of the film substrate 11 It is a porous film containing titanium oxide (TiO ₂ ) formed on a surface (hereinafter referred to as “one surface”) on the opposite side to the surface in contact with the film substrate 11 in (a).

The porous film 10 has a function of receiving and transporting electrons from a sensitizing dye to be described later, and includes a porous semiconductor containing titanium oxide, and is formed in a substantially rectangular shape on one side 12a of the transparent electrode film 12 It is done.

The porous film 10 is formed by, for example, a non-heating process that does not use any heat at the time of film formation.

As the non-heating process, a known method is used, and examples thereof include a spraying method, a cold spraying method, and an aerosol deposition method (hereinafter abbreviated as "AD method").

The spraying method is a technique of heating a sprayed material (in this embodiment, titanium oxide fine particles) and spraying it onto a substrate to form a thin film (porous film 10 in this embodiment) on the substrate. As a heat source for heating the sprayed material, combustion salt or plasma is used, and the sprayed material in the form of droplets or particulates is sprayed onto the substrate by a high-speed gas stream or the like. A thin film is formed when the spray material in the form of droplets or particulates solidifies and adheres on the substrate.

The cold spray method is a technique of colliding a powder material (in this embodiment, titanium oxide fine particles) with a substrate at a solid state below the melting temperature to form a thin film (porous film 10 in this embodiment) on the substrate. to be.

With the AD method, raw material particles (in this embodiment, titanium oxide fine particles) are accelerated to subsonic to supersonic speed by a carrier gas containing an inert gas such as helium, argon or nitrogen, and the raw material particles are injected at a high speed to the substrate. It is a technique of forming a thin film on a substrate by bonding the raw material particles to the substrate or the raw material particles.

At least a part of the raw material particles that have collided with the substrate surface enters the substrate surface, so that the material is not easily peeled off. In addition, by continuing spraying, separate fine particles collide with the raw material particles that have dug into the substrate surface, and by the collision of the raw material particles, a new surface is formed on the surface of each of the raw material particles, and mainly the raw material in this new surface. The particles are joined together. In the collision of the raw material particles, the temperature rise at which the raw material particles are melted is unlikely to occur, so that the interface layer where the raw material particles are joined is substantially free of a glassy grain boundary layer. Then, by continuing spraying of the raw material particles, a number of raw material particles are gradually joined to the substrate surface to form a dense thin film. The formed thin film has a sufficient strength as a porous film constituting the photoelectric conversion layer of the dye-sensitized solar cell (DSSC), and thus plastic curing by firing is unnecessary.

As the AD method, for example, the ultrafine particle beam deposition method disclosed in the "International Publication No. WO01 / 27348A1 pamphlet" and the brittle material ultrafine particle low temperature molding method disclosed in "Japanese Patent Publication No. 32,5481" are used.

In these known AD methods, it is important to pre-treat the raw material particles to be sprayed with a ball mill or the like so that internal deformations such as cracks or not are preliminarily applied to the raw material particles. It is said that by applying this internal deformation, it is easy to cause crushing or deformation when the injected fine particles collide with a substrate or already deposited raw material particles, and as a result, a denser film can be formed.

In addition, in the present embodiment, it is not necessary to preliminarily apply internal deformation to the raw material particles by pretreatment.

In this embodiment, it is preferable to perform a non-heating process at room temperature.

Here, the normal temperature refers to a temperature sufficiently lower than the melting point of the raw material fine particles of the porous membrane 10, and is substantially a temperature of 200 ° C or lower.

It is preferable that the temperature of a normal temperature environment is below the melting point of the film substrate 11. It is preferable that the temperature of the normal temperature environment is less than the glass transition temperature of the film substrate 11.

The porous film 10 formed by the non-heating process as described above has a critical load of 8 mN or more, preferably 10 mN or more, and more preferably 15 mN or more.

Since the porous membrane 10 has a critical load of 8 mN or more, the adhesion strength to the transparent electrode membrane 12 is high, and when the dye-sensitized solar cell using the porous membrane 10 is bent, the porous membrane 10 is transparent There is no case of peeling from the electrode film 12. Therefore, the dye-sensitized solar cell using the porous membrane 10 can be made flexible.

The porous membrane for a dye-sensitized solar cell of the present invention has a film thickness of 8 to 12 μm, a variation in film thickness of preferably ± 1 μm, a film thickness of 8 to 12 μm, and a film thickness variation of ± It is more preferably 0.5 µm.

If the film thickness is too thick, there is a risk of cracking or peeling due to film stress. Therefore, the film thickness is preferably 12 µm or less. On the other hand, if the film thickness is too thin, the adhesion is good, but the amount of dye adsorption becomes insufficient, the generated current is reduced, and there is a fear that the conversion efficiency is lowered. Therefore, the film thickness is preferably 8 µm or more.

In addition, the smaller the variation in the film thickness, the more the bias of the stress and the location of concentration are eliminated, which is preferable from the viewpoint of adhesion.

In addition, the porous film 10 formed by the non-heating process as described above is Japanese Industrial Standard JIS K5600-5-4 "Paint General Test Method-Part 5: Mechanical Properties of the Coating Film-Section 4: Scratching Hardness (Pencil Method ) ”, The pencil hardness is H or more, and preferably 4H or more.

Since the porous film 10 has a pencil hardness of H or more, the adhesion strength to the transparent electrode film 12 is high, and when the dye-sensitized solar cell using the porous film 10 is bent, the porous film 10 The transparent electrode film 12 is not peeled off. Therefore, the dye-sensitized solar cell using the porous membrane 10 can be made flexible.

The porous membrane 10 preferably has a porosity of 15 to 50%, more preferably 15 to 40%, and even more preferably 20 to 35%.

When the porosity of the porous membrane 10 is less than 15%, the membrane is too dense, and it is difficult to sufficiently adsorb the dye, so that the conversion efficiency may be lowered. On the other hand, when the porosity of the porous membrane 10 is more than 50%, the membrane becomes brittle because there are too many pores, and there is a fear of breaking when the film is bent.

In addition, in this invention, "porosity" is the value computed by image analysis from the SEM image of the cross section of the porous membrane 10.

In addition, since the porous film 10 is formed by the non-heating process as described above, the crystal structure of the raw material fine particles (titanium oxide fine particles) is not changed (deformed) by heat, and the crystal structure is not deformed or crystal defects are small. It is a porous membrane. In particular, as the non-heating process, when the above-described AD method is used, aerosol (raw fine particles) is transparent electrode film 12 on film substrate 11 by spraying aerosol onto transparent electrode film 12 on film substrate 11. ), The contact between the transparent electrode film 12 on the film substrate 11 and the raw material fine particles and the raw material fine particles is increased by the impact upon impact to the transparent electrode film 12 of the porous film 10. . Therefore, the dye-sensitized solar cell using the porous film 10 obtained by the above is excellent in photoelectric conversion efficiency. In addition, since the raw material fine particles collide with the transparent electrode film 12 at a speed, the adhesion strength of the raw material fine particles to the transparent electrode film 12 increases, and therefore, when the porous film 10 is applied to a flexible device, the porous material The film 10 is not peeled off.

In addition, in the present invention, it is not necessary to use a solvent or a binder when forming the porous film 10. Therefore, since the porous membrane 10 has no shrinkage or specific voids in the removal step of the solvent or binder, and there are no factors that inhibit adhesion, it is possible to stably form a film having high adhesion.

As the film substrate 11, a material having high light transmittance is used, and for example, polyethylene terephthalate (PET), acrylic, polycarbonate, polyethylene naphthalate (PEN), polyimide, or the like includes a transparent resin material, Flexible film.

It is preferable that the glass transition temperature (Tg) of the film substrate 11 is less than 200 degreeC. Moreover, it is preferable that the glass transition temperature (Tg) of the film substrate 11 is 80 degreeC or more practically.

As the transparent electrode film 12, a conductive material such as tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), zinc oxide (ZnO), or the like is used for sputtering or printing to form the film substrate 11. What was formed into one surface 11a is mentioned.

(Method for manufacturing porous membrane for dye-sensitized solar cell)

Next, the manufacturing method of the porous membrane for dye-sensitized solar cells of this embodiment is demonstrated.

In the method of manufacturing a porous film for dye-sensitized solar cells, a porous film containing titanium oxide is produced by a non-heating process on one surface 11a (one surface 12a of the transparent electrode film 12) of the film substrate 11. (10) is formed.

In the present embodiment, in the method of manufacturing a porous membrane, the non-heating process is performed by dispersing the raw material fine particles of the porous membrane 10 in a carrier gas to form an aerosol, and the aerosol is one side 12a of the transparent electrode film 12 It will be described with reference to a film forming method of forming a porous film 10 containing raw material fine particles by spraying on, i.e., the AD method.

In this embodiment, the film forming apparatus 20 shown in FIG. 2 is used, for example.

The film forming apparatus 20 accommodates the film substrate 11 on which the transparent electrode film 12 is installed, and the film forming chamber 21 for forming the porous film 10 on one side 12a of the transparent electrode film 12 It is equipped with.

In the film production room 21, a stage 22 having an arrangement surface 22a for placing the film substrate 11 is provided. The stage 22 is movable in the horizontal direction with the film substrate 11 disposed.

A vacuum pump 23 is connected to the production chamber 21. By the vacuum pump 23, the inside of the film production room 21 becomes negative pressure.

In addition, a nozzle 24 having a rectangular opening portion 24a is disposed in the production chamber 21.

The nozzle 24 has a transparent electrode film 12 in which the opening 24a is provided on the film surface 11 disposed on the surface 22a of the stage 22, that is, on the surface 22a of the stage 22. It is arranged so as to face one surface 12a of.

The nozzle 24 is connected to the gas cylinder 26 through the conveying pipe 25.

In the middle of the conveying pipe 25, a mass flow controller 27, an aerosol generator 28, a disintegrator 29, and a classifier 30 are provided in order from the gas cylinder 26 side.

In the film forming apparatus 20, nitrogen gas, which is a conveying gas, is supplied from the gas cylinder 26 to the conveying pipe 25, and the flow rate of the nitrogen gas is adjusted by the mass flow controller 27.

 The aerosol generator 28 is loaded with the raw material fine particles for injection, and the raw material fine particles are dispersed in nitrogen gas flowing in the conveying pipe 25, and the raw material fine particles are conveyed to the disintegrator 29 and the classifier 30.

Then, from the nozzle 24, the raw material fine particles 41 are jetted to one surface 12a of the transparent electrode film 12 at a subsonic to supersonic speed.

Here, the detail of the manufacturing method of a porous membrane is demonstrated.

First, the film substrate 11 on which the transparent electrode film 12 is provided is disposed on the arrangement surface 22a of the stage 22 in the film production room 21.

Subsequently, the inside of the film production chamber 21 is set to a negative pressure by the vacuum pump 23.

Subsequently, nitrogen gas is supplied into the film forming chamber 21 from the gas cylinder 26 through the conveying pipe 25, and the inside of the film forming chamber 21 is set to a nitrogen gas atmosphere.

Subsequently, a porous film 10 containing titanium oxide is formed on one surface 12a of the transparent electrode film 12 provided on the film substrate 11 by the AD method.

In order to form the porous membrane 10, the aerosol generator 28 is loaded with raw material fine particles containing titanium oxide, the raw material fine particles are dispersed in nitrogen gas flowing in the conveying tube 25, and the disintegrator 29 and It conveys to the classifier 30. Then, the raw material fine particles 41 containing titanium oxide are injected from the opening 24a of the nozzle 24 to one surface 12a of the transparent electrode film 12 provided on the film substrate 11.

In this embodiment, the case where TiO ₂ particles are used as raw material fine particles will be described as an example. The average particle diameter of TiO ₂ is preferably 1.0 nm to 5.0 μm, and more preferably 1.0 nm to 2.0 μm.

In this embodiment, other TiO ₂ particles may be used or used in combination, in which case the preferred average particle diameter of the other TiO ₂ particles may be the same as the preferred average particle diameter of the TiO ₂ particles, and TiO ₂ It may be smaller or larger than the particles.

The porous film 10 having pores (pores) capable of sufficiently supporting the DSSC dye (sensitizer dye) can be formed by being at least the lower limit of the above range.

By being less than or equal to the upper limit of the above range, a porous film 10 having a more suitable strength can be formed on the DSSC optical electrode.

In addition, the average particle diameter of TiO ₂ is determined as a peak value of a particle diameter (volume average diameter) distribution obtained by a method of measuring and averaging a plurality of particle diameters by SEM observation or a measurement by a laser diffraction particle size distribution measuring device. There is a way to do it.

In the present embodiment, as the raw material fine particles, a plurality of particles having different particle sizes, for example, small-diameter particles and large-diameter particles may be used in combination.

The average particle diameter r of the small-diameter particles is, for example, preferably 1 nm or more and less than 1000 nm (1 μm), more preferably 1 nm or more and less than 500 nm, even more preferably 1 nm or less and less than 200 nm, and particularly 1 nm or more and 100 nm or less. desirable.

The average particle diameter R of the large-diameter particles is, for example, preferably 0.2 μm or more and 100 μm or less, more preferably 0.2 μm or more and 50 μm or less, still more preferably 0.2 μm or more and 5 μm or less, and more preferably 0.2 μm or more and 2 Particularly preferred is µm or less.

When a small-diameter particle and a large-diameter particle are used together, the relative ratio (r / R) of the average particle diameter r of the small-diameter particles and the average particle diameter R of the large-diameter particles is (1/1000) ≤ (r / R) ≤ It is preferable to satisfy the relationship (1/5). It is more preferable that the relative ratio (r / R) satisfies the relationship of (1/750) ≤ (r / R) ≤ (1/10), and (1/500) ≤ (r / R) ≤ (1 / It is more preferable to satisfy the relationship of 20), and it is particularly preferable to satisfy the relationship of (1/250) ≤ (r / R) ≤ (1/30).

When the relative ratio (r / R) satisfies the above relationship, the difference between the average particle diameter r of the small-diameter particles and the average particle diameter R of the large-diameter particles becomes clearer. When the small-diameter particles and the large-diameter particles contain the same inorganic material (for example, titanium oxide), the difference in the average particle diameter becomes more apparent by the weight of the individual particles of the small-diameter particles and the individual particles of the large-diameter particles. It means that the car becomes clearer.

As the raw material fine particles, when a small-diameter particle and a large-diameter particle are used together, mixed particles of a small-diameter particle having an average particle diameter of 1 to less than 200 nm and a large-diameter particle having an average particle diameter of 0.2 to 2 µm are preferable, and an average particle diameter of 1 Mixed particles of small-diameter particles having an average particle diameter of 0.5 to 2 μm and smaller particles having an average particle diameter of 1 to 50 nm are more preferable, and mixing of small-diameter particles having an average particle diameter of 1 to 50 nm and large-diameter particles having an average particle diameter of 1 to 2 µm Particles are more preferred.

In the present invention, by making the difference in weight more clear, it is preferable because the setting of the injection conditions in consideration of the difference in weight can be performed more easily. For example, when the difference in the above weight is relatively large, when a mixed particle of small-diameter particles and large-diameter particles is sprayed onto a substrate to form a film, large-diameter particles are given to the small-diameter particles rather than the collision energy between the small-diameter particles. The collision energy can be significantly increased. That is, in the film forming process, the collided small diameter particles collide against the small diameter particles that have reached on the substrate or adjacent separate particles, so that the collided small diameter particles are pressed against the substrate or adjacent adjacent particles. , Or rubbed, it is possible to more reliably bond the small-diameter particles to the substrate or to separate particles adjacent to the small-diameter particles.

However, when the difference in weight is extremely large, the collided small-diameter particles may break up to shatter, and it may be difficult to form a porous film. In addition, if the difference in weight is extremely small, the degree to which the energy contributed by the large diameter particles colliding with the small diameter particles when the small diameter particles are bonded to the substrate or adjacent separate particles is relatively small. Loses.

When the relative ratio (r / R) satisfies the above relationship, the difference in weight can be set to an appropriate range, and a porous film excellent in strength and electronic conductivity can be formed on the substrate.

In the mixed particles, the mixing ratio of the large-diameter particles: small-diameter particles is preferably 99.9 parts by weight: 0.1 parts by weight to 0.1 parts by weight: 99.9 parts by weight, and 99.9 parts by weight: 0.1 parts by weight to 50 parts by weight: 50 parts by weight More preferably, the denier is 99.9 parts by weight: 0.1 parts by weight to 70 parts by weight: 30 parts by weight, more preferably 99.5 parts by weight: 0.5 parts by weight to 70 parts by weight: 30 parts by weight, more preferably 99 parts by weight: It is more preferably 1 part by weight to 80 parts by weight: 20 parts by weight.

When the mixing ratio of the large-diameter particles to the small-diameter particles is within the above range, the large-diameter particles can be more reliably collided with the small-diameter particles on the substrate. As a result, the strength and electronic conductivity of the porous film formed on the substrate can be further enhanced.

Particularly, in addition to the above effects, a porous film having high adhesion can be formed on the substrate by mixing the large-diameter particles: small-diameter particles in a range of 99.9 parts by weight: 0.1 parts by weight to 70 parts by weight: 30 parts by weight. .

For the injection of the large-diameter particles and the small-diameter particles, the mixture may be injected from the same nozzle, or the large-diameter particles and the small-diameter particles may be injected from separate nozzles. Further, it is also possible to alternately spray large-diameter particles and small-diameter particles from separate nozzles.

In the present embodiment, the speed of TiO ₂ particles accelerated by the carrier gas (nitrogen gas) is preferably 10 to 1000 m / s, more preferably 10 to 250 m / s.

By being below the upper limit of the above range, when the TiO ₂ particles collide with the film substrate 11 or the already deposited TiO ₂ particles, the film is thin while maintaining the particle diameter at the time of spraying without excessively crushing. Can form.

By being more than the lower limit of the above range, the TiO ₂ particles can be reliably bonded to the film substrate 11 or the TiO ₂ particles already deposited, thereby forming a porous film 10 of sufficient strength.

The speed of the TiO ₂ particles accelerated by the carrier gas may be appropriately adjusted within the above range depending on the type of the transparent electrode film 12.

In this embodiment, it is preferable that the injection of TiO ₂ particles is performed in a normal temperature environment.

Here, the normal temperature refers to a temperature sufficiently lower than the melting point of the TiO ₂ particles, and is substantially 200 ° C. or less.

The temperature in the normal temperature environment is preferably equal to or less than the melting point of the film substrate 11 and preferably less than the glass transition temperature of the film substrate 11.

In the present embodiment, when forming the porous film 10, it is not necessary to apply internal deformation to the injected TiO ₂ particles in advance. When the TiO ₂ particles have an appropriate strength, the TiO ₂ particles are not crushed during film formation, and the structure is easy to maintain, and voids (pore) can be formed between the bonded TiO ₂ particles. Thereby, the porous film 10 having a large specific surface area can be formed.

On the other hand, when forming a dense porous film 10, TiO ₂ particles to which internal deformation has been previously applied may be used.

In the present embodiment, when the porous membrane 10 is formed, its porosity is also affected by the injection speed and the injection angle, but the factor mainly affecting is the particle diameter of the injected TiO ₂ particles. Within the above-mentioned preferred particle diameter range, the larger the particle diameter, the higher the porosity, and the smaller the particle diameter, the lower the porosity.

In addition, by using the AD method, even when a material having low heat resistance (low melting point) is used as the film substrate 11, the film substrate 11 is not warped or deformed by heat, and the porous film 10 is formed. Can form. Therefore, by using the AD method, the types of materials of the film substrate 11 that can be used are increased.

In addition, when forming the porous film 10, since the film substrate 11 does not cause distortion or deformation due to heat, the dye-sensitized solar cell is manufactured using the film substrate 11 on which the porous film 10 is formed. When it does, in the bonding process of this film substrate 11 and another member, the problem that the adhesiveness of both is worsened is less likely to occur. In particular, by using the AD method, when the film substrate 11 on which the porous film 10 is formed is applied to the roll-to-roll method, the porous film 10 is removed from the transparent electrode film 12. There is an advantage that the problem of peeling becomes difficult to occur.

In addition, in the conventional method, since a porous film is formed by applying heat to titanium oxide, it is easy to induce crystal defects and crystal defects in the titanium oxide fine particles, and as a result, the electronic conductivity of the porous film is lowered. Therefore, when the porous film is used as a photoelectric conversion layer of a dye-sensitized solar cell, the photoelectric conversion efficiency of the photoelectric conversion layer decreases.

Since the AD method is a process that does not require high temperature, a porous film (photoelectric conversion layer) can be formed while maintaining the crystal structure of the raw material particles. Therefore, the electron conductivity of the photoelectric conversion layer is improved, and when the photoelectric conversion layer is used as a photo electrode of a dye-sensitized solar cell, the photoelectric conversion efficiency is improved.

In addition, in this embodiment, although the porous film 10 can be formed by one film formation, it is also preferable to perform multiple film formations. By forming a plurality of films with good adhesion to form a plurality of films, the adhesion of the porous film 10 to the film substrate 11 can be ensured, and the uniformity of the film thickness of the porous film 10 (variation suppression) It is also possible to secure.

"Dye-sensitized solar cell" Fig. 3 is a schematic cross-sectional view showing a dye-sensitized solar cell as a second embodiment of the present invention.

In the dye-sensitized solar cell 50 of the present embodiment, a pair of first and second opposing substrates 51 and 52 and a pair of transparent opposingly arranged at predetermined intervals between the substrates The electrode film 53 and the counter electrode film 54, the photoelectric conversion layer 55 and the electrolyte layer 56 formed between the electrode films, and the sealing surrounding the photoelectric conversion layer 55 and the electrolyte layer 56 It is schematically composed of resin 57.

The transparent electrode film 53 is formed on the surface of the first substrate 51 that faces the second substrate 52 (hereinafter referred to as "one surface") 51a.

The counter electrode film 54 is formed on a surface (hereinafter referred to as "one surface") 52a of the second substrate 52 that faces the first substrate 51.

The photoelectric conversion layer 55 is formed on a surface (hereinafter referred to as "one surface") 53a of the transparent electrode film 53 that faces the opposite electrode film 54.

The sealing resin 57 is provided between the first substrate 51 on which the transparent electrode film 53 is provided and the second substrate 52 on which the counter electrode film 54 is provided, and adheres the substrate at a predetermined interval. In addition, the gap formed by the substrate is sealed (sealed).

The electrolyte layer 56 is an electrolyte filled in a gap formed by the first substrate 51 on which the transparent electrode film 53 is installed, the second substrate 52 on which the counter electrode film 54 is installed, and the sealing resin 57 It is formed by. Further, the electrolyte layer 56 is in contact with the transparent electrode film 53, the counter electrode film 54, and the photoelectric conversion layer 55.

The first substrate 51, the transparent electrode film 53 and the photoelectric conversion layer 55 form the photoelectrode substrate 58.

The second substrate 52 and the counter electrode film 54 form a counter electrode substrate 59.

As the first substrate 51 and the second substrate 52, the same ones as the film substrate 11 are used.

The transparent electrode film 53 includes a conductive material such as tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), zinc oxide (ZnO), and the first substrate 51 by sputtering or printing. What was formed into one surface 51a of the is mentioned.

The counter electrode film 54 includes, for example, a conductive material such as platinum, polyaniline, polyethylenedioxythiophene (PEDOT), or carbon, and one surface of the second substrate 52 by sputtering or printing ( 52a).

As the photoelectric conversion layer 55, the above-mentioned porous film 10 is used.

A sensitizing dye is supported on the photoelectric conversion layer 55.

The sensitizing dye is composed of an organic dye or a metal complex dye.

As the organic dye, various organic dyes such as coumarin-based, polyene-based, cyanine-based, hemicyanine-based, and thiophene-based are used, for example.

As a metal complex pigment, a ruthenium complex etc. are used suitably, for example.

As the electrolyte for forming the electrolyte layer 56, non-aqueous electrolyte solvents such as acetonitrile or propionitrile, liquid components such as ionic liquids such as dimethylpropyl imidazolium iodide or butyl methyl imidazolium iodide, lithium iodide, etc. And a solution in which the supporting electrolyte and iodine are mixed. Moreover, these electrolyte solutions may contain t-butylpyridine. In addition, in order to improve the durability of the solar cell, an ionic liquid electrolyte or a solid electrolyte may be used as the electrolyte.

In addition, iodine-based compounds such as dimethylpropyl imidazolium iodide and butyl methyl imidazolium iodide are materials having a property of corroding metal (metal corrosive materials).

As the resin forming the sealing resin 57, for example, an ultraviolet curable resin, a thermosetting resin, a thermoplastic resin and the like are used.

Although the thickness of the sealing resin 57 is not particularly limited, it is appropriate that the transparent electrode film 53 and the counter electrode film 54 are spaced apart at a predetermined interval, and that the electrolyte layer 56 is required. Is adjusted.

According to the dye-sensitized solar cell 50, since the porous film 10 formed by the non-heating process is used as the photoelectric conversion layer 55, as described above, the transparent electrode film of the photoelectric conversion layer 55 ( When the adhesion strength to 53) is high and the dye-sensitized solar cell 50 is bent, the photoelectric conversion layer 55 is not peeled off from the transparent electrode film 53. Therefore, the dye-sensitized solar cell 50 can be made flexible. In addition, since the photoelectric conversion layer 55 does not change (deteriorate) the crystal structure of titanium oxide by heat, and there is little deformation or crystal defect of the crystal structure, the dye-sensitized solar cell 50 has excellent photoelectric conversion efficiency. Do.

Next, "the manufacturing method of a dye-sensitized solar cell", and the dye-sensitized solar cell manufacturing method of this embodiment is demonstrated with reference to FIGS. 4-6.

The dye-sensitized solar cell manufacturing method of the present embodiment comprises: (I) a substrate forming step of forming a photoelectrode substrate and a counter electrode substrate, and (II) bonding a photoelectrode substrate and a counter electrode substrate formed by a substrate forming step. A substrate bonding process is provided.

(I) substrate formation process

First, a transparent electrode film 53 made of tin-doped indium oxide, fluorine-doped tin oxide, zinc oxide, or the like is formed on one surface 51a of the first substrate 51 by sputtering, printing, or the like ( See Figure 4).

Subsequently, as described above, the photoelectric conversion layer 55 (porous film 10) containing titanium oxide is formed on one surface 53a of the transparent electrode film 53 by a non-heating process.

Subsequently, the photoelectric conversion layer 55 is immersed in a sensitizing dye solution formed by dissolving a sensitizing dye in a solvent, and the sensitizing dye is supported on the photoelectric conversion layer 55 to obtain a photoelectrode substrate 58.

In addition, the method for supporting the sensitizing dye on the photoelectric conversion layer 55 is not limited to a method of immersing the photosensitive conversion layer 55 in the sensitizing dye solution, and the sensitizing dye is continuously moved while the photoelectric conversion layer 55 is moved. A method of injecting, immersing or increasing the photoelectric conversion layer 55 in the solution is also employed.

Further, after the sensitizing dye is supported on the photoelectric conversion layer 55, the surface of the photoelectric conversion layer 55 can also be washed with anhydrous alcohol or the like.

Subsequently, a sealing resin 57 is applied to one side 53a of the transparent electrode film 53 by an inkjet method or the like so as to surround the photoelectric conversion layer 55 at a predetermined distance from the photoelectric conversion layer 55. To form.

When surrounding the photoelectric conversion layer 55 of the sealing resin 57, the sealing resin 57 may not have a predetermined distance from the photoelectric conversion layer 55.

Here, when the photoelectrode substrate 58 and the opposing electrode substrate 59 are joined, the transparent electrode film 53 and the opposing electrode film 54 are spaced apart at predetermined intervals, and the electrolyte layer 56 is also provided. The thickness of the sealing resin 57 is adjusted so as to be the required thickness.

A counter electrode film 54 made of platinum, polyaniline, polyethylenedioxythiophene (PEDOT), carbon, or the like is formed on one surface 52a of the second substrate 52 by sputtering, printing, or the like, to form a counter electrode. A substrate 59 is obtained (see FIG. 5).

(II) Substrate bonding process

The sealing resin is formed by bonding the optical electrode substrate 58 and the counter electrode substrate 59 through the sealing resin 57 formed on the optical electrode substrate 58, and subjecting the sealing resin 57 to heat treatment or light irradiation treatment. By (57), the photoelectrode substrate 58 and the counter electrode substrate 59 are adhered and fixed (see Fig. 6).

A gap is formed between the photoelectrode substrate 58 and the counter electrode substrate 59 by this substrate bonding process.

Subsequently, an electrolyte is injected into the gap between the photoelectrode substrate 58 and the opposing electrode substrate 59 from an injection port (not shown) formed in advance on the photoelectrode substrate 58 or the opposing electrode substrate 59, and the photo The electrolyte layer 56 is formed between the electrode substrate 58 and the counter electrode substrate 59.

Subsequently, the injection port is sealed to obtain a dye-sensitized solar cell 50 as shown in FIG. 3.

Example

Hereinafter, the present invention will be described in more detail with reference to specific examples. However, the present invention is not limited to the examples shown below.

[Example 1]

(Production of porous membrane for dye-sensitized solar cells)

As a film substrate, a PEN film (125 µm thick) in which a transparent electrode film containing tin-doped indium oxide (ITO) was formed on one side was prepared.

Next, a porous film containing titanium oxide was formed on the transparent electrode film provided on the film substrate by the AD method. The obtained porous film had a thickness of about 10 μm.

As titanium oxide, rutile-type large-diameter particles having a particle diameter of 2 µm and anatase-type small-diameter particles having a particle diameter of 25 nm were mixed and used at a ratio of 90:10 by weight.

In addition, formation of the porous film by the AD method was performed under the following conditions.

Gas: nitrogen

Gas volume: 2SLM

Temperature: room temperature (about 25 ℃)

Film chamber pressure: 100Pa

Substrate conveying speed: 5 mm / sec.

Number of film formation (number of scans): 10 to 40 times (adjusted so that the film thickness becomes 10 µm)

(Evaluation of adhesion of porous membrane)

The adhesion of the obtained porous film to the film substrate was evaluated by measuring the critical load and pencil hardness of the porous film.

The ultra-thin scratch tester (trade name: Model CSR-2000, manufactured by RHESCA, Inc.) measured the critical load (unit: mN) of the porous membrane in accordance with Japanese Industrial Standard JIS-R3255 `` Test Method for Adhesion of Thin Films Using Glass as a Substrate '' ). Table 1 shows the results.

The pencil hardness of the porous film was measured by a method conforming to Japanese Industrial Standard JIS K5600-5-4 "General Test Methods for Paints-Part 5: Mechanical Properties of Painted Films-Section 4: Scratch Hardness (Pencil Method)". Did. Table 1 shows the results.

Further, the film substrate (film-forming body) on which the porous film was installed was wound 10 times in a cylinder having a diameter of 80 mm and a cylinder having a diameter of 25 mm, and visually checking whether the film-forming body was peeled off was evaluated for bending resistance. Table 1 shows the results.

(Production of dye-sensitized solar cells)

Further, a dye-sensitized solar cell was produced using a film substrate provided with a porous membrane.

First, an N719 dye solution was prepared in which the dye N719 was dissolved in a mixed solvent of acetonitrile / tert-butanol (1/1, volume ratio) so that the concentration was 0.3 mM.

Subsequently, the film substrate provided with the porous film was dried under a nitrogen gas atmosphere at room temperature under a dry atmosphere at 100 ° C., and then immersed in a N719 dye solution for 18 hours to prepare the photoelectrode substrate of Example 1.

As a counter electrode substrate, ITO, chromium, and platinum were deposited in this order on a film substrate containing a PEN film (125 µm thick) to form a film.

The counter electrode substrate and the photoelectrode substrate were clipped by overlapping with a resin gasket (separator) having a thickness of 30 µm, and the electrolyte solution (AN50, manufactured by Solaronics) was injected between both electrodes to increase or decrease the dye of Example 1. A solar cell was obtained.

(Evaluation of photoelectric conversion efficiency of dye-sensitized solar cells)

The photosensitive conversion efficiency of the dye-sensitized solar cell of Example 1 was measured as follows.

Under the conditions of AM1.5 pseudo-sunlight of 100 mW / cm 2 of incident light, an output current value was measured while scanning a DC voltage at 50 mV / sec using a current voltage measuring device to obtain a current-voltage characteristic.

The photoelectric conversion efficiency was calculated based on this current-voltage characteristic. Table 1 shows the results.

[Examples 2 to 4]

(Production of porous membrane for dye-sensitized solar cells)

Dye-sensitized type was added in the same manner as in Example 1, except that, as titanium oxide, rutile-type large-diameter particles having a particle diameter of 2 µm and anatase-type small-diameter particles having a particle diameter of 25 nm were mixed and used in a weight ratio shown in Table 1. A porous membrane for solar cells was produced.

In the same manner as in Example 1, the adhesion of the obtained porous film to the film substrate was evaluated. Table 1 shows the results.

Further, in the same manner as in Example 1, a dye-sensitized solar cell was produced using a film substrate provided with a porous membrane.

In the same manner as in Example 1, the photoelectric conversion efficiency of the dye-sensitized solar cell of Comparative Example 1 was measured. Table 1 shows the results.

[Comparative Example 1]

The same film substrate as in Example 1 was prepared, and on a transparent electrode film provided on the film substrate, a low-temperature baking paste (manufactured by Pexel) was applied by screen printing, and fired at 120 ° C for 30 minutes to include titanium oxide. A porous film to be formed was formed. The obtained porous film had a thickness of about 10 μm.

In the same manner as in Example 1, the adhesion of the obtained porous film to the film substrate was evaluated.

Table 1 shows the results.

Further, in the same manner as in Example 1, a dye-sensitized solar cell was produced using a film substrate provided with a porous membrane.

In the same manner as in Example 1, the photoelectric conversion efficiency of the dye-sensitized solar cell of Comparative Example 1 was measured. Table 1 shows the results.

[Comparative Example 2]

A glass substrate having a thickness of 1.1 mm was prepared, and on a transparent electrode film provided on the glass substrate, a high temperature firing paste (manufactured by Solaronics) was applied by screen printing, and fired at 500 ° C. to form a porous oxide containing titanium oxide. A film was formed. However, in Comparative Example 2, after the high-temperature firing, the porous membrane was broken by the membrane stress. Therefore, each evaluation measurement could not be performed.

[Comparative Example 3]

A porous membrane for a dye-sensitized solar cell was produced in the same manner as in Comparative Example 2, except that the thickness of the porous membrane was about 5 μm.

In the same manner as in Example 1, the adhesion of the obtained porous film to the film substrate was evaluated. Table 1 shows the results.

Further, in the same manner as in Example 1, a dye-sensitized solar cell was produced using a film substrate provided with a porous membrane.

In the same manner as in Example 1, the photoelectric conversion efficiency of the dye-sensitized solar cell of Comparative Example 1 was measured. Table 1 shows the results.

From the results of Table 1, it was found that in Examples 1 to 4, although the porous film was formed by the AD method of the non-heating process, the adhesion of the porous film to the film substrate was high and the photoelectric conversion efficiency was high.

On the other hand, in Comparative Example 1, although film formation was performed at low temperature firing, it was found that the adhesion of the porous film to the film substrate was not only very low, but also the photoelectric conversion efficiency was lower than Examples 1 to 4.

Further, in Comparative Example 2, a film was formed by firing at a high temperature using a glass substrate, but after firing, the film was broken by film stress. Therefore, the critical load, pencil hardness, bending test, and conversion efficiency could not be measured.

In addition, in Comparative Example 3, the same operation as in Comparative Example 2 was performed except that the film thickness of the porous membrane was changed to about 5 μm. As a result, the critical load, pencil hardness, and conversion efficiency were equal to or higher than in Example 1. However, in Comparative Example 3, since film formation was performed at high temperature firing, a porous film cannot be formed on the film substrate.

Further, in Examples 1 to 4, the particle mixing ratio was adjusted in the range of large diameter: small diameter = 70:30 to 96: 4, but if large diameter: small diameter = 70 parts by weight or more and 30 parts by weight or less, It was confirmed that the adhesion of the porous film to the film substrate was high and the photoelectric conversion efficiency was high.

The preferred embodiments of the present invention have been described above, but the present invention is not limited to these embodiments. It is possible to add, omit, substitute, and change other components without departing from the spirit of the present invention. The invention is not limited by the foregoing description, but only by the scope of the appended claims.

10: porous membrane for dye-sensitized solar cell (porous membrane)
11: film substrate
12: transparent electrode film
50: dye-sensitized solar cell
51: first substrate
52: second substrate
53: transparent electrode film
54: counter electrode film
55: photoelectric conversion layer
56: electrolyte layer
57: sealing resin
58: photoelectrode substrate
59: counter electrode substrate

Claims (13)

A porous film comprising titanium oxide formed on a film substrate, wherein the critical load is 8 mN or more, the porous film is formed by a non-heating process, and the non-heating process converts the raw material fine particles of the porous film to a temperature below its melting point. A porous film for a dye-sensitized solar cell, characterized in that it is a film-forming method of spraying a film substrate to form a porous film containing the raw material fine particles. The porous membrane for a dye-sensitized solar cell according to claim 1, wherein the non-heating process is performed at 200 ° C or lower. The porous membrane for a dye-sensitized solar cell according to claim 1 or 2, wherein the film thickness is 8 to 12 μm, and the variation in film thickness is ± 1 μm. The porous membrane for a dye-sensitized solar cell according to claim 1 or 2, wherein the porosity of the porous membrane is 15 to 50%. The dye-sensitized type according to claim 1 or 2, wherein the raw material fine particles are mixed particles of large-diameter particles having an average particle diameter of 0.2 to 2 µm and small-diameter particles having an average particle diameter of less than 1 to 200 nm. Porous membrane for batteries. The porous membrane for a dye-sensitized solar cell according to claim 5, wherein a mixing ratio of the large-diameter particles and the small-diameter particles is 99.9 parts by weight: 0.1 parts by weight to 70 parts by weight: 30 parts by weight. The porous membrane for a dye-sensitized solar cell according to claim 1 or 2, wherein a glass transition temperature (Tg) of the film substrate is less than 200 ° C. A dye-sensitized solar cell comprising a pair of opposing substrates, a pair of electrode films facing each other between these substrates, and a photoelectric conversion layer and an electrolyte layer formed between these electrode films, wherein the photoelectric conversion layer is A dye-sensitized solar cell comprising the porous membrane for the dye-sensitized solar cell according to claim 1 or 2. A method of manufacturing a porous membrane for dye-sensitized solar cells,
A method for producing a porous membrane for a dye-sensitized solar cell, wherein a porous membrane having a critical load of 8 mN or more is formed on the film substrate by a non-heating process in which the raw material fine particles are sprayed onto the film substrate at a temperature equal to or lower than the melting point. The porous membrane for a dye-sensitized solar cell according to claim 1, wherein the non-heating process is an aerosol deposition method. The porous membrane for a dye-sensitized solar cell according to claim 6, wherein a mixing ratio of the large-diameter particles and the small-diameter particles is 70 parts by weight: 30 parts by weight to 96 parts by weight: 4 parts by weight. The method of manufacturing a porous membrane for a dye-sensitized solar cell according to claim 9, wherein the non-heating process is an aerosol deposition method. The method of claim 9, wherein the raw material fine particles are mixed particles of large-diameter particles having an average particle diameter of 0.2 μm to 2 μm and small-diameter particles having an average particle diameter of less than 1 nm to 200 nm. The mixing ratio, 70 parts by weight: 30 parts by weight to 96 parts by weight: a method for producing a porous membrane for dye-sensitized solar cell, characterized in that 4 parts by weight.

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