JP2001345125A - Photoelectric conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion element with a small resistance loss, low transmission loss, high photoelectric conversion efficiency, no electrolyte leakage, and keeping high photoelectric conversion efficiency for a long time. SOLUTION: This photoelectric conversion element has an electrode whose at least one surface is covered with a semiconductor layer; a counter electrode facing the semiconductor layer of the electrode; and an electrolyte layer arranged between the semiconductor layer of the electrode and the counter electrode, the semiconductor layer is composed of a conductive material and a semiconductor material, and/or a layer comprising conductive fine particles is arranged between the electrode and the semiconductor layer, and/or the electrolyte layer is composed of a porous supporting body and the electrolyte filled in the porous supporting body.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a photoelectric conversion element. More specifically, the present invention relates to a photoelectric conversion element having a novel structure having high photoelectric conversion efficiency and excellent long-term reliability.

[0002]

2. Description of the Related Art Solar cells are greatly expected as a clean energy source, and pn junction type solar cells and the like have already been put to practical use. On the other hand, photochemical cells that extract electric energy using a chemical reaction in a photo-excited state have been developed by many researchers, but in terms of practical application, they far exceed pn junction type solar cells, which have already been proven. Did not.

[0003] Among conventional photochemical batteries, a type utilizing an oxidation-reduction reaction comprising a sensitizer and an electron acceptor is known. For example, there is a system in which a thionin dye and iron (II) ion are combined. Since the discovery of the Honda-Fujishima effect,
Photochemical cells utilizing photocharge separation of metals and their oxides are also known. When a semiconductor comes into contact with a metal, a Schottky junction can be formed due to the relationship between the work function of the metal and the semiconductor, but a similar junction can be made when the semiconductor is in contact with the solution. For example, Fe ²⁺ / Fe ³⁺ , Fe (CN) ₆
^4- / Fe (CN) ₆ ³⁻ , I ⁻ / I ₂ , Br ⁻ / Br ₂ , hydroquinone / quinone, etc., and when an nd type semiconductor is immersed in a solution, it will be near the surface of the semiconductor Electrons move to the oxidizing agent in the solution to reach an equilibrium state. As a result, the vicinity of the surface of the semiconductor is positively charged and a potential gradient is generated. Accordingly, a gradient also occurs in the conduction band and the valence band of the semiconductor.

When the surface of a semiconductor electrode immersed in an oxidation-reduction solution is irradiated with light, light having energy equal to or greater than the band gap of the semiconductor is absorbed, and electrons are transferred to the conduction band near the surface,
Generates holes in the valence band. The electrons excited in the conduction band are transmitted to the inside of the semiconductor by the above-described potential gradient existing near the surface of the semiconductor, while the holes generated in the valence band rob electrons from the reductant in the redox solution.

When a circuit is formed between a metal electrode and a semiconductor by immersing the metal electrode in an oxidation-reduction solution, the reduced form whose electrons have been deprived of holes diffuses through the solution, receives electrons from the metal electrode, and is reduced again. You. By repeating this cycle, the semiconductor electrode functions as a negative electrode and the metal electrode functions as a positive electrode, so that electric power can be supplied to the outside. Therefore, the photovoltaic power is the difference between the redox level of the redox solution and the Fermi level in the semiconductor.

In order to increase the photovoltaic power, a redox solution having a low oxidation-reduction level, that is, a redox solution having a strong oxidizing power is used, and a large difference is generated between the oxidation-reduction level and the Fermi level in a semiconductor. That is, a semiconductor which can be produced, that is, has a large band gap is used.

However, if the oxidizing power of the redox solution is too large, an oxide film is formed on the surface of the semiconductor itself,
The photocurrent stops within a short time. The band gap is generally 3.0 eV.
The semiconductor having a voltage of 2.0 eV or less has a problem that it is easily dissolved in a solution by a current flowing at the time of photoelectric conversion. For example, n-Si forms an inactive oxide film on the surface by light irradiation in water, and n-GaAs and n-CdS dissolve oxidatively.

In order to solve these problems, attempts have been made to coat a semiconductor with a protective film, and a p-type conductive polymer such as polypyrrole, polyaniline or polythiophene having a hole transporting property is coated with a semiconductor protective film. Ingenuity has been proposed. However, there is a problem with durability,
At best, it was stable for only a few days.

In order to solve the problem of photolysis, it is conceivable to use a semiconductor having a band gap of 3 eV or more.
The intensity peak is too large to efficiently absorb sunlight having a peak near 2.5 eV. Therefore, only ultraviolet rays of sunlight can be absorbed, and the visible region which occupies most of the sunlight is not absorbed at all, and the photoelectric conversion efficiency is extremely low.

In order to achieve both effective use of the visible light region and photostability of a semiconductor having a large band gap, a dye having a semiconductor loaded with a sensitizing dye that absorbs visible light of a longer wavelength smaller than the band gap of the semiconductor. Sensitized solar cells are known. The difference from a conventional wet solar cell using a semiconductor is a photocharge separation process in which electrons are excited by irradiating light to a dye, and the excited electrons move from the dye to the semiconductor.

Dye-sensitized solar cells are often associated with photosynthesis. At first, chlorophyll was considered as a pigment, as in photosynthesis.However, unlike natural chlorophyll, which is constantly replaced with new chlorophyll, pigments used in solar cells have problems in terms of stability. Also had a photoelectric conversion efficiency of less than 0.5%. It is very difficult to simulate the process of photosynthesis in nature as it is to construct a solar cell.

As described above, the dye-sensitized solar cell attempts to absorb long-wavelength visible light with a hint from photosynthesis. However, since the electron conduction mechanism has become complicated, the dye-sensitized solar cell has a loss. Growth was a problem. In a solid-state solar cell, the absorption efficiency can be increased by increasing the thickness of the light-absorbing layer. However, for dye-sensitized solar cells, electrons can be injected into the semiconductor electrode only from the monolayer on the surface. Therefore, in order to eliminate useless absorption of light, it is desirable that the dye on the semiconductor surface be a monomolecular layer.

In order to efficiently inject electrons in the excited dye into the semiconductor, the dye is preferably chemically bonded to the semiconductor surface. For example, with respect to titanium oxide, it is important that the dye has a carboxyl group in order to chemically bond to the semiconductor surface.

An important improvement in this regard is that of Fu.
It is a group of jihira and others. They reported in 1977 to Nature in 1977 that the photocurrent was more than 10 times that of the conventional adsorption method due to the ester bond of the carboxyl group of rhodamine B with the hydroxyl group on the SnO ₂ surface. This is because the ester bond of the ester bond is closer to the surface of the semiconductor in the dye than the conventional amide bond, in which the electron which absorbed light energy exists.

However, even if electrons can be effectively injected into the semiconductor, electrons in the conduction band may recombine with the ground level of the dye, or may recombine with the redox substance. Due to such a problem, the photoelectric conversion efficiency remained low despite the above-described improvement in electron injection.

As described above, a major problem of the conventional dye-sensitized solar cell is that only a sensitizing dye carried in a single layer on the semiconductor surface can inject electrons into the semiconductor. In other words, single-crystal and polycrystalline semiconductors, which have been often used for semiconductor electrodes, have a smooth surface and no pores inside, and the effective area where the sensitizing dye is carried is equal to the electrode area. Is small.

Therefore, when such an electrode is used, the sensitizing dye of the monolayer supported on the electrode can absorb only 1% or less of the incident light even at the maximum absorption wavelength, and the light use efficiency is extremely poor. Become. Attempts have been made to increase the number of sensitizing dyes in order to increase the light-collecting power, but generally no sufficient effect has been obtained.

Grettzel et al., As a means for solving such a problem, made the titanium oxide electrode porous, carried a sensitizing dye, and significantly increased the internal area (for example,
Patent No. 2664196). This titanium oxide porous film was prepared by a sol-gel method, and the porosity of the film was about 50%, and a nanoporous structure having a very high internal surface area was formed. For example, with a film thickness of 8 μm, the roughness factor (the ratio of the actual area inside the porous body to the substrate area) reaches about 720. When this surface is geometrically calculated, the concentration of the sensitizing dye is 1.2 × 10 ⁻⁷ mol / cm.
^As a result, about 98% of the incident light will be absorbed at the wavelength of maximum absorption.

The new dye-sensitized solar cell, also referred to as a Gretzell cell, is capable of dramatically increasing the amount of sensitizing dye carried by the above-mentioned porous titanium oxide, efficiently absorbing sunlight, and supporting the semiconductor on a semiconductor. A major feature is that a sensitizing dye having an extremely high electron injection speed has been developed.

Have developed a bis (bipyridyl) Ru (II) complex for dye-sensitized solar cells. The Ru complex has the structure of the general formula cis-X2bis (2,2'-bipyridyl-4,4'-dicarboxylate) Ru (II). X is Cl-, CN-, SCN-. A systematic study was performed on the fluorescence, visible light absorption, electrochemical and photo-redox behavior of these. Of these,
It has been shown that cis- (diisocyanate) -bis (2,2′-bipyridyl-4,4′-dicarboxylate) Ru (II) has remarkably excellent performance as a solar absorber and a dye sensitizer. Was done.

The visible light absorption of the dye sensitizer is a charge transfer transition from a metal to a ligand. Also, the carboxyl group of the ligand coordinates directly to the Ti ion on the surface, forming a close electronic contact between the dye sensitizer and titanium oxide. Due to this electronic contact, electron injection from the dye sensitizer into the conduction band of titanium oxide occurs at a very high speed of 1 picosecond or less, and the conduction band of titanium oxide by the oxidized dye sensitizer in the opposite direction. It is said that the re-capture of the injected electrons occurs on the order of microseconds. This difference in speed produces the directionality of photoexcited electrons, which is the reason why charge separation is performed with extremely high efficiency. This is a difference from a pn junction solar cell that separates electric charges by a potential gradient of a pn junction surface, and is an essential feature of the Gretzell cell.

The structure of the Grettzel cell is a sandwich type cell in which an electrolyte solution containing a redox couple is sealed between two conductive glass substrates coated with a fluorine-doped tin oxide transparent conductive film. One of the glass substrates is one in which a porous film composed of colloidal titanium oxide ultrafine particles is laminated on a transparent conductive film, and a sensitizing dye is further adsorbed to form a working electrode. The other is a transparent conductive film coated with a small amount of platinum to serve as a counter electrode. A spacer is sandwiched between two glass substrates, and an electrolyte solution is injected into a very small gap between the two glass substrates by using a capillary phenomenon. The electrolyte solution uses a mixed solvent of ethylene carbonate and acetonitrile, obtained by the iodide tetra -n- propyl ammonium and iodine as solutes, I ^- /
Including the I ^3- of oxidation-reduction pair. Platinum coated on the counter electrode is an I ^3- this redox couple I ^- there is a catalytic effect of cathodic reduction to.

The principle of operation of the Grettzel cell is basically the same as that of a conventional wet solar cell using a semiconductor. However, the reason why the photocharge separation response is performed uniformly and efficiently in any part of the porous electrode such as the Gretzell cell is mainly because the electrolyte layer is a liquid. That is, only by immersing the dye-carrying porous electrode in the solution, the solution is uniformly diffused into the porous material and an ideal electrochemical interface can be formed.

The feature of the Grettzel cell is that the roughness factor is remarkably improved by using ultrafine particles of titanium oxide, and the amount of sensitizing dye carried is increased. As a result, higher photoelectric conversion efficiency than the conventional dye-sensitized solar cell is realized. Therefore, in order to achieve higher photoelectric conversion efficiency, it is necessary to increase the roughness factor,
It is conceivable to increase the thickness of the porous film of titanium oxide.

However, when the roughness factor is increased, the ultrafine particles are connected by point contact, and there is a problem that the contact resistance sharply increases. Also, when the film thickness is large, the movement distance of the electrons in the titanium oxide becomes long, and in the titanium oxide having a lower conductivity than the metal, there is a problem that the loss due to the resistance or the loss due to the recombination increases. That is, in the production of a porous film using ultrafine particles of titanium oxide, it is difficult to improve the electric conductivity of the porous film because titanium oxide having poor electric conductivity is used. Further, as another problem, it has been recognized that, in the process of light passing through the titanium oxide semiconductor, the transmission distance of the light in the titanium oxide becomes longer and the transmission loss increases.

As a solution to the former problem, for example, Japanese Unexamined Patent Publication No. 10-112337 discloses that a conductive surface is anodized by coating the surface of the metal with a porous metal oxide so that the conductive substrate can be oxidized. A method is described in which an integral structure of a film is used to reduce the electric resistance at the interface. However,
When this method is used, there is a limitation that metallic titanium must be used as a substrate.

For example, Japanese Patent Application Laid-Open No. 8-81222 discloses that the surface of a porous film composed of ultrafine particles of titanium oxide is etched with a mineral acid to reduce lattice defects and impurities and increase the amount of dye carried. A method is described. In this method, the surface of the titanium oxide ultrafine particles is modified to expect effective electron injection from the sensitizing dye to the titanium oxide, and the electrical conductivity of the porous film remains unchanged.

In order to reduce the resistance of the porous film of titanium oxide, the film thickness may be reduced. However, as the amount of sensitizing dye carried decreases, photoexcited electrons injected from the sensitizing dye into titanium oxide are reduced. And a sufficient photocurrent cannot be obtained. That is, considering the reduction in the resistance of the porous film, it becomes difficult to increase the carrying amount of the sensitizing dye. Such a trade-off relationship occurs because titanium oxide must simultaneously fulfill two functions of a function of a photocharge separation response and a function of providing a roughness factor for obtaining a sufficient amount of a sensitizing dye carried. Because. Due to this trade-off relationship, the photoelectric conversion rate of the conventional titanium oxide / sensitizing dye-based photoelectric conversion element was not always sufficient.

Further, in the Gretzell cell, there is a problem that the internal resistance generated at the interface between the semiconductor layer and the transparent electrode causes a decrease in the conversion efficiency of the solar cell. In order to solve this problem, for example, Japanese Patent Application Laid-Open No. H10-290018 describes a method of maintaining the conductivity of a semiconductor layer by mixing a conductive material into the semiconductor layer. However, in this method, when the electrons excited by the incident light move through the mixed film of the semiconductor particles and the conductive material, the electrons are trapped by the conductive material having high conductivity, which may hinder the electron transfer. No improvement in efficiency can be expected.

Japanese Patent Application Laid-Open No. 10-112337 discloses that a metal substrate is anodized and the surface is coated with a porous metal oxide to form an integrated structure of a conductive substrate and an oxide film, and the interface between the conductive substrate and the oxide film is formed. A method for reducing the electrical resistance at the time is described. However, when this method is used, there is a restriction that metal titanium must be used as a base material, and there is a concern about an increase in cost.

Also, in the case of a Grettzel cell, when a liquid layer is used as the electrolyte layer, there is a problem that the leakage of the electrolyte solution occurs prior to the deterioration of other battery components, thereby deteriorating the performance of the solar cell. Met.

As a solution to the former problem, for example, a conductive polymer (for example,
K. Murakoshi et.al., Chem. Lett., 1997, pp.471-47
2) and amorphous hole transport agents (U. Bach et. Al, Na
Nature, 395, 583 (1998)) and solid ion conductors (JP-A-7-288142 and JP-A-8-23).
Some attempts have been made to solve the above-mentioned problems by using such techniques as disclosed in Japanese Patent Application Laid-Open No. 6165). However, in the above-described method in which the electrolyte layer is solidified, the contact area between the electrolyte layer and the electrode is reduced and the internal resistance is increased, or because the electron mobility of the solid electrolyte layer itself is low, the liquid electrolyte There is a new problem that the photoelectric conversion efficiency is reduced as compared with the layer.

JP-A-9-27352 and JP-A-11-126917 describe the use of an electrolyte layer in which an electrolyte is held by a polymer compound having a crosslinked structure. However, in the present invention, since the oxidation-reduction pair in the electrolyte solution moves in the polymer compound having a cross-linked structure, the mobility of the oxidation-reduction pair in the electrolyte layer decreases, and the dye on the surface of the semiconductor layer and There is a problem that the electron transfer reaction between the counter electrode and the oxidation-reduction pair is rate-determining and the conversion characteristics deteriorate.

[0034]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a photoelectric conversion element having low resistance loss and low transmission loss and capable of achieving high photoelectric conversion efficiency. Another object of the present invention is to provide a photoelectric conversion element that does not leak and that can maintain excellent photoelectric conversion efficiency for a long period of time.

[0035]

The first object of the present invention is to provide at least an electrode having a semiconductor layer adhered on at least one surface, a counter electrode facing the semiconductor layer of the electrode, and In a photoelectric conversion element having an electrolyte layer disposed between a semiconductor layer and a counter electrode, the semiconductor layer is made of a conductive substance and a semiconductor material, and / or between the electrode and the semiconductor layer. The problem can be solved by disposing a layer made of conductive fine particles on the substrate. The second object is to provide at least an electrode having a semiconductor layer attached on one surface;
In a photoelectric conversion element having a counter electrode facing the semiconductor layer of the electrode and an electrolyte layer disposed between the semiconductor layer and the counter electrode of the electrode, the electrolyte layer includes a porous support and a porous support. The problem is solved by comprising the electrolyte solution filled in the porous support. The features described above and can be used in combination as appropriate, whereby a photoelectric conversion element having excellent characteristics that cannot be achieved by the related art can be obtained.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have conducted intensive studies to reduce the loss caused by a semiconductor material. As a result, a semiconductor in a dye-sensitized solar cell is formed in a place where the semiconductor and the sensitizing dye are in contact with each other. It has been found that it is only necessary to have a photoelectric conversion function. That is, in order to improve the conversion efficiency of the dye-sensitized solar cell, it is effective to replace a semiconductor portion that does not contribute to photoelectric conversion with a material having low resistance loss and transmission loss as a means of reducing loss occurring in the semiconductor. I found something.

According to one embodiment of the present invention, by depositing a thin film of semiconductor on the outer surface of the conductive material,
(a) semiconductors (eg, titanium oxide) can be made as thin as necessary to provide a field for photocharge separation, and (b) to obtain a porous film with a high roughness factor, By using high conductive particles, the electric conductivity of the porous film can be improved. Thereby, the trade-off relationship of the dye-sensitized titanium oxide semiconductor photoelectric conversion element of the related art can be completely solved. In other words, by coating the surface of the conductive substance with a thin semiconductor film, the resistance loss generated when moving in the semiconductor film can be reduced, and the electrons generated by charge separation move in the conductive particles, so that the porous film is formed. It is possible to reduce the resistance generated when moving inside.

Further, the present inventors have discovered that the small contact area between the semiconductor layer and the electrode and the resulting increase in resistance at the interface contribute to an increase in the resistance loss of the entire photoelectric conversion element. The semiconductor layer has a nanoporous structure having an extremely high internal surface area formed by semiconductor fine particles having a large specific surface area. On the other hand, the electrode has a smaller surface area than the semiconductor layer and a smaller contact area with the semiconductor layer. In order to obtain an excellent photoelectric conversion element, it has been found that it is effective to increase the contact area between the semiconductor layer and the electrode and reduce the resistance at the interface.

According to an embodiment of the present invention, the contact area between the semiconductor layer and the electrode is increased by disposing a layer made of conductive fine particles between the electrode and the semiconductor layer, thereby increasing the contact area between the electrode and the semiconductor layer. Resistance at the interface can be reduced.

According to the study of the present inventors, the electrolyte present in the porous semiconductor layer having a pore size of several nm to several μm has an electrolyte retention effect by capillary action derived from the structure of the semiconductor layer. However, the electrolyte existing in such a manner as to fill the gap of several μm to several mm between the semiconductor layer and the counter electrode does not work as well as the capillary effect as in the semiconductor layer, so that the electrolyte in this portion flows out. I learned that it is easy to do. That is, in order to obtain a photoelectric conversion element that does not leak and can maintain excellent photoelectric conversion efficiency for a long time,
It has been discovered that it is important to prevent leakage of the electrolyte present between the semiconductor layer and the counter electrode, not the electrolyte present in the semiconductor layer.

Further, by providing a porous support so as to exert a holding effect only on the electrolyte present between the semiconductor layer and the counter electrode, a solid electrolyte layer or a polymer compound having a crosslinked structure is provided. It is possible to suppress a decrease in the mobility of the oxidation-reduction pair, as compared with the electrolyte layer held in the form described above, whereby high photoelectric conversion efficiency can be achieved.
Was.

Hereinafter, the photoelectric conversion device of the present invention will be specifically described with reference to the drawings. First, as a means of reducing the loss generated in the semiconductor, the present invention is to improve the conversion efficiency of the dye-sensitized solar cell by replacing the semiconductor portion that does not contribute to photoelectric conversion with a material having low resistance loss and transmission loss. An embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a schematic sectional view of an example of the photoelectric conversion element of the present invention. As shown, the photoelectric conversion element 1 of the present invention has a transparent electrode 5 formed on one surface of a transparent substrate 3. On one surface of the transparent electrode 5, a semiconductor layer 7 is formed. Further, a counter electrode 9 exists opposite the semiconductor layer 7. The counter electrode 9 is a separate transparent substrate 11
Is formed on one surface. An electrolyte layer 13 exists between the semiconductor layer 7 and the transparent counter electrode 9.

The semiconductor layer 7 includes a thin film 15 of a conductive substance,
It is composed of a semiconductor thin film 17 formed on the surface of the thin film 15. A sensitizing dye 19 is carried on the surface of the semiconductor thin film 17.

The thickness of the conductive material thin film 15 is generally
It is preferable that the thickness be in the range of 1 to 50 μm. If the thickness of the conductive material film 15 is less than 1 μm, the amount of the sensitizing dye carried is small, and disadvantages such as insufficient generation of photoelectrons occur, which is not preferable. On the other hand, if the thickness of the conductive material film 15 is more than 50 μm, it is not preferable because adverse effects such as a decrease in light transmittance of the semiconductor layer 7 and an increase in resistance loss occur. A preferred range of the thickness of the conductive material film 15 is 3 to 40 μm, and a more preferred range is 5 to 40 μm.
~ 30 μm, the most preferred range is 10-20 μm
It is.

The thickness of the semiconductor film 17 covering the conductive material is generally in the range of 2 to 100 nm. If the thickness of the semiconductor film 17 is less than 2 nm, there is a possibility that a portion where the semiconductor film 17 does not cover the conductive substance 15 or 21 may occur, which is not preferable. On the other hand, if the thickness of the semiconductor film 17 is 10
If the thickness exceeds 0 nm, adverse effects such as an increase in resistance loss of the semiconductor film 17 occur, which is not preferable. The preferred range of the thickness of the semiconductor film 17 is 10 to 60 nm, and the more preferred range is 30 to 50 nm.

Instead of the planar conductive material film as shown in FIG. 1, a particulate conductive material 2 shown in FIG.
The semiconductor film 17 can be directly coated on the surface of the semiconductor device 17.
On the outer surface of the semiconductor film 17, as in FIG.
Are carried, and the semiconductor layer 7 is formed as a whole.

The photoelectric conversion element of the present invention is a photoelectric conversion element 1
Is composed of the conductive material film 15 coated with the semiconductor 17, the roughness factor of the semiconductor layer 7 is large, and a large amount of the sensitizing dye 19 can be carried. Furthermore, since a light-transmitting material is used as the conductive substance 15, the sensitizing dye can efficiently absorb light.

As the conductive substance, tin oxide, zinc oxide, aluminum oxide, silicon oxide, indium trioxide,
Fine particles of one or more crystalline metal oxides selected from strontium trioxide and the like, or composite oxides of these metal oxides may be used. For example, fine particles containing tin oxide as a main component and containing 1 to 20 mol% of strontium trioxide or antimony oxide are examples of effective composite oxide conductive materials. In addition, there is a pastel manufactured by Mitsui Kinzoku Mining Co., Ltd., in which barium sulfate or aluminum borate is used as a core material, and the core material is coated with tin oxide, tin oxide treated with a dopant, ITO (Indium tin Oxide), or the like.
Furthermore, if the metal fine particles also have the following light transmittance,
It can be used as a conductive substance used in the present invention.

The volume resistivity of the conductive particles is 10 ⁷ Ω-cm.
Or less, preferably 10 ⁵ Ω-cm or less, particularly preferably 10 Ω-cm or less. The lower limit at this time is not particularly limited, but is usually about 10 ⁻⁹ Ω-cm.

The particle size of the conductive particles is from 1 nm to 500 nm.
Or less, preferably 100 nm or less. When the particle size of the conductive particles is 500 nm or more, it is necessary to increase the roughness factor by increasing the thickness of the semiconductor layer constituting the photoelectric conversion element, and there is a problem that the light transmittance of the semiconductor layer is reduced. When the thickness is 500 nm or less, such a problem does not occur, and when the thickness is 100 nm or less, the semiconductor layer can have high transmittance and roughness factor.

The light transmittance of the conductive particles is preferably such that the transmittance of a thin film made of only the conductive particles is 60% or more. If the light transmittance is less than 60%, the amount of light applied to the sensitizing dye carried on the semiconductor layer is reduced, which causes disadvantages such as insufficient generation of photoelectrons, which is not preferable.

As the semiconductor material to be coated on the conductive particles, Cd, Zn, In, Pb, Mo, W, Sb, Bi,
Cu, Hg, Ti, Ag, Mn, Fe, V, Sn, Z
oxides of r, Sr, Ga, Si, Cr, SrTiO ₃ ,
Perovskite such as CaTiO ₃ or Cd
S, ZnS, In ₂ S ₃ , PbS, Mo ₂ S, WS ₂ , Sb
₂ S ₃ , Bi ₂ S ₃ , ZnCdS ₂ , sulfide of Cu ₂ S, Cd
Se, In ₂ Se ₃ , WSe ₂ , HgSe, PbSe, C
dTe metal chalcogenide, other GaAs, Si,
Se, Cd ₂ P ₃ , Zn ₂ P ₃ , InP, AgBr, PbI
₂ , HgI ₂ and BiI ₃ are preferred. Alternatively, a composite containing at least one selected from the above semiconductors, for example, CdS / TiO ₂ , CdS / AgI, Ag ₂ S / Ag
I, CdS / ZnO, CdS / HgS, CdS / Pb
S, ZnO / ZnS, ZnO / ZnSe, CdS / Hg
S, CdS _x / CdSe _1-x , CdS _x / Te _1-x , CdS
_{e x / Te 1-x,} ZnS / CdSe, ZnSe / CdS
_{e, CdS / ZnS, TiO 2} / Cd 3 P 2, CdS / C
dSeCd _y Zn _1-y S, the CdS / HgS / CdS preferred.

The value of the element ratio Y / X of the metal element Y contained in the semiconductor film 17 to the metal element X contained in the conductive particles 15 or 21 constituting the semiconductor layer 7 in the photoelectric conversion element 1 of the present invention is as follows. It is preferable that it is 0.1 or more and 8.0 or less. When the value of Y / X is 0.1 or less, the thickness of the semiconductor film on the surface of the conductive particles becomes 2 nm or less on average, and there is a possibility that a portion not covered by the semiconductor film may be generated. In this case, the surface area of the semiconductor film 17 where the sensitizing dye 19 is carried becomes small, and as a result, the sensitizing element carrying amount decreases and the output characteristics of the photoelectric conversion element 1 deteriorate.
When the value of Y / X is 8.0 or more, the effect of reducing the resistance loss obtained by replacing the semiconductor portion that does not contribute to the photoelectric conversion with a material having a small resistance loss is reduced, and as a result, the output characteristics of the solar cell are reduced. The improvement effect cannot be obtained.

Here, the value of Y / X can be determined as follows. The electrode provided with the semiconductor layer 7 is washed with an ethanol solution to remove the attached electrolytic solution, and the sensitizing dye 19 is further removed with an alkaline ethanol solution.
Subsequently, the semiconductor layer 7 on the transparent electrode 5 is separated from the electrode. If the separation method can separate the transparent electrode and the semiconductor layer,
Any method may be used. As such a separation method, for example, a method of applying vibration with ultrasonic waves or a method of scraping off may be mentioned. In this manner, only the semiconductor layer 7 is taken out, analyzed by fluorescent X-ray analysis, and a method of measuring and evaluating the element ratio of the metal element Y contained in the semiconductor film to the metal element X contained in the conductive particles is used. Can be determined by

Further, the electrode provided with the semiconductor layer 7 is washed with an ethanol solution to remove the adhered electrolytic solution, and the sensitizing dye 19 is further removed with an alkaline ethanol solution. After separating from the electrode and taking out only the semiconductor layer 7, the semiconductor layer 7 is dissolved with an acid, and the metal element Y contained in the semiconductor film with respect to the metal element X contained in the conductive particles contained in the solution. The ratio can be measured and evaluated by an atomic absorption method or an ICP method.

Further, when the conductive particles and the semiconductor film contain several kinds of metal elements, X and Y are the total of the metal elements in the conductive particles and the total of the metal elements in the semiconductor film. .

As shown in FIG. 1, a planar semiconductor layer is formed, for example, by applying a slurry liquid composed of conductive fine particles to a surface of a substrate 3 having a transparent electrode 5 by a known and conventional method (for example, a doctor blade or a bar coater, etc.). Application method, spray method, dip coating method, screen printing method, spin coating method, etc.)
By heating and sintering at a temperature in the range of 400 ° C. to 600 ° C. to form a porous conductive material film 15, and then forming a film made of semiconductor fine particles or a semiconductor film 17 on the porous film. Can be prepared. A liquid phase deposition method, a sol-gel method, an electroless plating method, an electrolytic plating method, a TiCl4 solution processing method, etc. are preferable as a method for forming a film or a semiconductor film composed of semiconductor particles uniformly covering a porous film composed of conductive particles. .

The conductive particles 21 coated with the semiconductor material 17 as shown in FIG. 2 can be obtained by adding the conductive particles to a sol solution of the semiconductor material. A semiconductor sol solution can be made by suspending ultrafine semiconductor particles in water,
It is prepared by a known method of hydrolyzing a metal alkoxide obtained by a reaction between an alcohol and a metal salt or a metal, or hydrolyzing a metal salt dissolved in the metal alkoxide. For example, as an alkoxide of titanium, tetraisopropyl titanate, tetrabutyl titanate, butyl titanate dimer, tetrakis (2-
Ethylhexyloxy) titanium, tetrastearyl titanate, triethanolamine titanate, diisopropoxy bis (acetylacetonato) titanium, titanium ethyl acetoacetate, titanium isopropoxyoctylene glycolate, titanium lactate, and the like.

Further, holes are formed in the semiconductor layer coated on the conductive particles so that the surface of the conductive particles is partially exposed,
For the purpose of further improving the electrical contact between the conductive particles, a known additive such as polyethylene glycol may be added to the sol solution of the semiconductor. Any diluent of the semiconductor sol solution may be used as long as it is compatible with the sol solution, and either a single solution or a mixture can be used without limitation. For example, as a dilute solution of a titanium oxide sol solution, ethanol, 1-propanol, 2-propanol, N-hexane, benzene, toluene, xylene, tricrene,
And propylene dichloride.

As a method for coating the conductive particles with the semiconductor from the semiconductor sol solution, the conductive particles were added to the sol solution, the sol solution was dropped on the conductive particle powder, or the conductive particles were scattered. There is a method of spraying a sol solution into a chamber. The thickness of the semiconductor film coated on the conductive particles cannot be unconditionally determined in relation to the particle size of the conductive particles, but is preferably 50 nm or less. The thickness is controlled by changing the time during which the sol solution and the conductive particles are mixed. If the mixing time is long, the conductive particles are not uniformly coated with the semiconductor, so the mixing time is preferably 60 seconds or less. Since the hydrolyzed semiconductor coated on the conductive particles has a hydroxyl group and the like and easily aggregates, the conductive particles must be immediately separated after mixing the semiconductor sol solution and the conductive particles. In order to minimize agglomeration, it is preferable that the conductive particles be separated and then washed with a liquid compatible with the semiconductor sol solution. Further, by this washing, conductive particles uniformly coated with a semiconductor having a thickness of 50 nm or less can be obtained.

In the case of a semiconductor layer as shown in FIG. 2, the conductive particles coated with the semiconductor obtained as described above are applied to the surface of the transparent electrode 5 of the substrate 3 and then heated and baked. Obtained by tying. The method of applying the conductive particles coated with the semiconductor includes an application method using a doctor blade or a bar coater, a spray method, a dip coating method, a screen printing method, and a spin coating method. In the heat sintering process, the conductive particles are sintered with each other to make the electrical contact stronger, and further, the semiconductor coated on the conductive particles can be crystallized. The heating temperature is set at 400 ° C. in consideration of the sintering rate, the degree of crystallization of the semiconductor, and the decrease in conductivity of the conductive particles due to thermal deterioration.
To 600 ° C. At a temperature of 400 ° C. or lower, a strong film cannot be obtained, and at a temperature of 600 ° C. or higher, the conductivity of the conductive particles is significantly reduced due to thermal degradation. It is preferable that the heating process until the heating temperature from 400 ° C. to 600 ° C. is reached is gradually performed from room temperature. By raising the temperature from room temperature, the conductive particles can be sintered without causing cracks in the semiconductor coated on the conductive particles. By repeating such application and heat sintering, a porous semiconductor film having any desired film thickness can be obtained.

By controlling the thickness of the porous semiconductor layer, the roughness factor (the ratio of the actual area inside the porous body to the substrate area) can be determined. The roughness factor is preferably 20 or more, and more preferably 150 or more. Roughness factor is 20
If it is less than 3, the amount of the sensitizing dye carried becomes insufficient, and the photoelectric conversion characteristics are not improved. The upper limit of the roughness factor is generally about 5000. The roughness factor increases as the thickness of the semiconductor layer increases, and the surface area of the semiconductor layer increases, and an increase in the amount of sensitizing dye carried can be expected. However, when the film thickness is too large, the influence of the light transmittance and the resistance loss of the semiconductor layer starts to appear. Further, if the porosity of the film is increased, the roughness factor can be increased without increasing the film thickness. However, if the porosity is too high, the contact area between the conductive particles decreases, and the effect of resistance loss must be considered. For this reason, the porosity of the film is preferably 50% or more, and the upper limit is generally about 80%. The porosity of the film can be calculated from the measurement result of the adsorption-desorption isotherm of nitrogen gas or krypton gas at the temperature of liquid nitrogen.

FIG. 3 is a schematic diagram illustrating the effect of the photoelectric conversion element 1 according to the present invention. (A) shows resistance loss and transmission loss in the conventional sensitized photoelectric conversion element 100. In the conventional photoelectric conversion element 100, a semiconductor layer 110 made of only a semiconductor material having a film thickness of D is attached to the transparent substrate 3 with the transparent electrode 5, and the sensitizing dye 19 is carried on the surface of the semiconductor layer 110. (B) is a dye-sensitized photoelectric conversion element 1 of the present invention.
Shows the resistance loss and the transmission loss at. In the dye-sensitized photoelectric conversion element 1 of the present invention, the thickness d of the semiconductor film 17 is only a necessary and sufficient value for exhibiting a photoelectric conversion function with the sensitizing dye 19. Therefore, d << D. Moreover, in the device 1 of the present invention, the space between the semiconductor film 17 and the electrode 5 is
There is a conductive particle layer 15 having a transmittance of 60% or more. For this reason, even with the same semiconductor layer, the transmission loss and the resistance loss of the semiconductor layer 7 in the element 1 of the present invention are significantly lower than the transmission loss and the resistance loss of the semiconductor layer 110 in the conventional element 100.

Referring back to FIG. Other components in FIG. 1 are known as components of the photoelectric conversion element. For example, as the transparent substrates 3 and 11, glass or plastic can be used. Because plastic is flexible, it is suitable for applications requiring flexibility. Substrate 3
Is preferably transparent because it functions as a light incident side substrate. On the other hand, the substrate 11 may be transparent or opaque, but light can be incident from both substrates.
Preferably, it is transparent.

The electrode 5 formed on one surface of the substrate 3 is
It is a metal film or a conductive film provided on glass or plastic. Preferred conductive materials include metals (eg, platinum, gold, silver, copper, aluminum, rhodium, indium, etc.), carbon, and conductive metal oxides (indium-tin composite oxide, fluorine-doped tin oxide, etc.). No.

The lower the surface resistance of the electrode 5, the better. The preferable range of the surface resistance is 50 Ω / sq or less, and more preferably 30 Ω / sq or less. The lower limit is not particularly limited, but is usually 0.1 Ω / sq.

The higher the light transmittance of the electrode 5, the better. The preferred light transmittance is 50% or more, more preferably 80% or more. The thickness of the electrode 5 is preferably 0.1 to 10 μm. When the thickness of the electrode 5 is less than 0.1 μm, it is difficult to form an electrode film having a uniform thickness. On the other hand, when the film thickness is more than 10 μm, the light transmittance is reduced, and sufficient light does not reach the semiconductor layer 7 and the sensitizing dye 19. Light is preferably incident from the electrode 5 on the side on which the semiconductor layer 17 is deposited.

By supporting the sensitizing dye molecules 19 on the semiconductor layer 7 of the present invention, a photoelectric conversion element having high photoelectric conversion efficiency can be obtained. As the sensitizing dye 19 used to be supported on the semiconductor layer 7 of the present invention, any dye commonly used in conventional dye-sensitized photoelectric conversion elements can be used. Such dyes are known to those skilled in the art. Such dyes are, for example, RuL ₂ (H ₂ O) ₂ type ruthenium-cis-
Diaqua-bipyridyl complex or ruthenium-tris (RuL
₃ ), ruthenium-bis (RuL ₂ ), osmium-tris (OsL
₃ ), transition metal complexes of osnium-bis (OsL ₂ ) type, zinc-tetra (4-carboxyphenyl) porphyrin, iron-hexacyanide complex, phthalocyanine and the like. As organic dyes, 9-phenylxanthene dyes, coumarin dyes, acridine dyes, triphenylmethane dyes, tetraphenylmethane dyes,
Examples include quinone dyes, azo dyes, indigo dyes, cyanine dyes, merocyanine dyes, and xanthene dyes. Among them, a ruthenium-bis (RuL ₂ ) derivative is preferable.

The amount of the sensitizing dye 19 carried on the semiconductor layer 7
10^-8-10^-6mol / cm ^TwoIf it is in the range of
And especially 0.1 to 9.0 × 10^-7mol / cm^TwoIs preferred
New When the amount of sensitizing dye 19 carried is 10^-8mol / cm^TwoNot yet
When it is full, the effect of improving the photoelectric conversion efficiency becomes insufficient. one
On the other hand, the loading amount of the sensitizing dye is 10^-6mol / cm^TwoSuper place
In this case, the effect of improving the photoelectric conversion efficiency saturates and becomes uneconomical.
It is.

The method for supporting the sensitizing dye 19 on the semiconductor layer 7 includes, for example, a method in which the substrate 3 on which the semiconductor layer 7 is adhered is immersed in a solution in which the sensitizing dye is dissolved. As a solvent for this solution, any solvent can be used as long as it can dissolve the sensitizing dye, such as water, alcohol, toluene, and dimethylformamide. As an immersion method, it is effective to heat and reflux or apply ultrasonic waves while the substrate with electrodes on which the semiconductor layer 7 is applied is immersed in the sensitizing dye solution for a certain period of time.

The counter electrode 9 functions as a positive electrode of the photoelectric conversion element 1 and has the same meaning as the electrode 5 on the side on which the semiconductor layer 7 is deposited. As the counter electrode 9 of the photoelectric conversion element 1 in the present invention, in order to efficiently act as a positive electrode of the photoelectric conversion element 1, platinum, graphite, or the like having a catalytic action of giving electrons to a reduced form of the electrolyte is preferable. Further, a conductive film made of a material different from that of the counter electrode 9 may be provided between the counter electrode 9 and the transparent substrate 11.

An electrolyte layer 13 exists between the semiconductor layer 7 carrying the sensitizing dye 19 and the counter electrode 9. The electrolyte is not particularly limited as long as the solvent contains a pair of oxidation-reduction constituents composed of an oxidant and a reductant, but is preferably an oxidation-reduction constituent in which the oxidant and the reductant have the same charge. . In this specification, the oxidation-reduction component is
In the oxidation-reduction reaction, a pair of substances reversibly existing in the form of an oxidized form and a reduced form. Such a redox-based constituent itself is known to those skilled in the art. Oxidation-reduction constituent materials that can be used in the present invention are, for example, chlorine compounds-chlorine,
Iodine compound-iodine, bromine compound-bromine, thallium ion (III)-thallium ion (I), mercury ion (II)-mercury ion (I), ruthenium ion (III)-ruthenium ion
(II), copper ion (II)-copper ion (I), iron ion (III)-iron ion (II), vanadium ion (III)-vanadium ion (II), manganate ion-permanganate ion, ferricia And quinone-hydroquinone, fumaric acid-succinic acid, and the like. Needless to say, other redox components can also be used. Among them, an iodine compound-iodine is preferable. Examples of the iodine compound include metal iodides such as lithium iodide and potassium iodide, quaternary ammonium salt compounds such as tetraalkylammonium iodide and pyridinium iodide, and dimethylpropyl iodide. Diimidazolium iodide compounds such as imidazolium are particularly preferred.

The solvent used for dissolving the electrolyte is preferably a compound which dissolves the redox constituents and has excellent ion conductivity. As the solvent, any of an aqueous solvent and an organic solvent can be used, but an organic solvent is preferable in order to further stabilize the oxidation-reduction constituent material. For example, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, ethylene carbonate, carbonate compounds such as propylene carbonate, methyl acetate, methyl propionate, ester compounds such as gamma-butyrolactone,
Diethyl ether, 1,2-dimethoxyethane, 1,3
Ether compounds such as dioxosilane, tetrahydrofuran and 2-methyl-tetrahydrafuran, 3-methyl-
Heterocyclic compounds such as 2-oxazodilinone and 2-methylpyrrolidone, acetonitrile, methoxyacetonitrile,
Nitrile compounds such as propionitrile, sulfolane,
Aprotic polar compounds such as didimethylsulfoxide and dimethylformamide; Each of these can be used alone, or two or more of them can be used in combination. Among them, carbonates such as ethylene carbonate and propylene carbonate
Compounds, heterocyclic compounds such as 3-methyl-2-oxazodylinone and 2-methylpyrrolidone, and nitrile compounds such as acetonitrile, methoxyacetonitrile and propionitrile are particularly preferred.

Next, another embodiment of the photoelectric conversion device of the present invention having a low resistance loss and capable of achieving high photoelectric conversion efficiency is shown in FIG. In the embodiment shown in FIG. 1, the conductive material 15 is a thin film having a dense and uniform film thickness in order to reduce the internal resistance. However, in the embodiment shown in FIG. A layer 25 made of 23 is provided between the electrode 5 and the semiconductor layer 7.

In the case of the structure shown in FIG. 1, the semiconductor layer 17 having a large specific surface area is in contact with the electrode made of the conductive material layer 1 having a dense structure, so that the contact area between the semiconductor layer and the electrode is small.
Loss due to resistance at the interface between the semiconductor layer and the electrode has been a factor in lowering the conversion efficiency. In the case of the structure of FIG. 4, the conductive particle layer is interposed between the semiconductor layer and the electrode, so that the contact between the semiconductor layer and the electrode can be maintained without impairing the characteristics such as the high specific surface area of the semiconductor and the low resistance of the electrode. The area is increased, the resistance at the interface is reduced, and high conversion efficiency is obtained.

As another method, as shown in FIG. 5, a conductive particle layer 2 is provided between a semiconductor layer 7 (see FIG. 2) made of a particulate conductive material 21 covered with a semiconductor film 17 and an electrode 5.
5 can also be interposed. Thereby, further excellent low resistance loss and low transmission loss can be obtained.

The conductive particles 23 used in the embodiments shown in FIGS. 4 and 5 are preferably light-transmitting. The light transmittance of the conductive particle layer 25 is preferably 60% or more. The light transmittance of the conductive particle layer 25 is 60%.
If it is less than 1, the amount of light applied to the sensitizing dye 19 carried on the semiconductor layer 7 decreases, and disadvantages such as insufficient generation of photoelectrons occur, which is not preferable. As such light-transmitting conductive fine particles, the same conductive material as those in FIGS. 1 and 2 can be used.

The particle size of the conductive particles 23 is 3 nm to 500 n.
It is preferably within the range of m. 3 nm to 100 nm
Is more preferably within the range. If the particle size of the conductive particles exceeds 500 nm, the specific surface area becomes extremely small.
The roughness factor cannot be increased, and the effect of using the conductive particle layer cannot be exhibited. On the other hand, when the particle size of the conductive particles is less than 3 nm, the workability of handling the particles is undesirably reduced.

The thickness of the conductive particle layer 25 is as follows.
Generally, it is preferable to be within the range of 10 to 3000 nm. If the thickness is less than 10 nm, the surface of the electrode 5 may be incompletely covered with the conductive particle layer 25, which is not preferable. On the other hand, if it exceeds 3000 nm, light transmission loss due to the conductive particle layer 25 increases, which is not preferable. The more preferable range of the thickness of the conductive particle layer 25 is 500 nm to 2500 nm.

FIG. 6 is a cross-sectional view of the photoelectric conversion element of the present invention which does not leak and can maintain excellent photoelectric conversion efficiency for a long period of time. In FIG. 6, the electrolyte layer 13
Is composed of a porous support 27 and an electrolyte filled and held in the porous support 27.

The term “porous support” in this specification means not only a space capable of holding an electrolytic solution, but also a space through which a redox couple in the electrolytic solution can pass, and itself is one independent member. Means a film-like structure formed as described above.
Therefore, the porous support having the structure as described above has a feature that it can be taken out as a single film when the photoelectric conversion element is disassembled.

The structure of the porous support 27 constituting the electrolyte layer 13 in the photoelectric conversion element 1 of the present invention may be a structure in which fibrous substances are superimposed, a structure having a lattice-like network structure, a structure in which Those having columnar voids in the normal direction are preferred. Therefore, as the porous support 27, for example, a filtration filter (membrane filter)
Alternatively, a separator or a nonwoven fabric used for a primary battery, a secondary battery, or the like can be suitably used. In particular, when there is a void penetrating in the normal direction to the surface of the porous support, a high photoelectric conversion efficiency can be obtained because the porous support 27 itself has little effect of inhibiting movement of the oxidation-reduction pair.

The material of the filter used as the porous support 27 of the present invention is preferably made of glass fibers, polyolefins such as polypropylene and polyethylene, and polyesters such as polyethylene terephthalate.

The material of the separator or nonwoven fabric used as the porous support 27 of the present invention includes polyolefins such as polypropylene and polyethylene, polyesters such as polyethylene terephthalate, polyamides, and the like.
Polyphenylene sulfide, vinylon (copolymer of vinyl chloride and vinyl acetate), polyimide, vinylon (acetalized polyvinyl alcohol) and the like are preferable. The separator or nonwoven fabric of these materials can be used alone, or a composite of two or more types of separators or nonwoven fabrics can be used. Here, "composite nonwoven fabric"
Is a blended stretched nonwoven fabric obtained by blending the above two types of materials and then melt-spinning / stretching, or a composite fiber (conjugated type fiber) comprising one of the above two types of materials as a core and the other covering the periphery thereof. Is a core-sheath structure type non-woven fabric obtained by heat-sealing. For example, a heat-sealing type nonwoven fabric using a high melting point polypropylene as a core component and a low melting point polyethylene as a sheath component is well known.

The thickness of the porous support 27 is determined by the surface distance between the semiconductor layer 7 and the counter electrode 9. However, in general, the thickness of the porous support 27 is preferably 1 mm or less. When the thickness of the porous support 27 is more than 1 mm, the movement distance of the oxidation-reduction pair in the electrolyte layer 13 becomes longer, and the electron transfer reaction mediated by the oxidation-reduction pair becomes rate-limiting, and the photoelectric conversion efficiency decreases.

Eliminating the space between the semiconductor layer 7 and the counter electrode 9 eliminates the portion of the electrolyte layer 13 in which the electrolyte holding mechanism of the porous support 27 does not work. Leads to improved performance. However, in order to eliminate the space between the semiconductor layer 7 and the counter electrode 9, the electrodes are strongly pressed against each other in the assembling process, so that the semiconductor layer 7 and the counter electrode 9 are mechanically broken and the photoelectric conversion efficiency is reduced. This can be a factor. Therefore, the distance between the semiconductor layer 7 and the counter electrode 9 is at least 1 μm.
It is preferable to provide the above intervals to prevent mechanical destruction of the semiconductor layer 7 and the counter electrode 9. Therefore, the thickness of the porous support 27 provided between the semiconductor layer 7 and the counter electrode 9 is preferably 1 μm or more.

The porous support 2 used to form the electrolyte layer 13 between the semiconductor layer 7 and the counter electrode 9 of the present invention
Reference numeral 7 must not only prevent the movement of the oxidation-reduction pair of the electrolyte filled between the semiconductor layer 7 and the counter electrode 9 but also keep these electrolytes from leaking. Therefore, the porous support 27 of the present invention does not prevent the movement of the oxidation-reduction pair of the electrolytic solution necessary for forming the photoelectric conversion element, and
It must have sufficient porosity (porosity) to hold the electrolyte so as not to leak.

Therefore, as the porous support 27 for forming the electrolyte layer 13 in the photoelectric conversion element 1 of the present invention, a porous material having a porosity in the range of 30% to 80% is used. It is preferred to use When the porous support 27 having a porosity of less than 30% is used, the effect of the porous support 27 preventing movement of the redox pair becomes large, and the electron transfer reaction mediated by the redox pair becomes rate-determining, and the photoelectric conversion is limited. Conversion efficiency decreases. On the other hand, when the porous support 27 having a porosity of more than 80% is used, the pore diameter becomes large, the ability to retain the electrolytic solution by the capillary action is reduced, and a sufficient effect of suppressing the liquid leakage cannot be obtained. It is more preferable to use a porous material having a porosity in the range of 35% to 70%. Most preferably, a porous material having a porosity in the range of 40% to 60% is used.

In FIG. 6, substrates 3 and 11, electrodes 5,
The counter electrode 9, the semiconductor layer 7, and the electrolytic solution may be as described with reference to FIGS.
Alternatively, it may be the same as in the prior art.

If the electrolyte layer 13 is a solid electrolyte layer or an electrolyte layer held by a polymer compound having a crosslinked structure, the problem of liquid leakage does not occur. Therefore, the following seven embodiments are possible as the photoelectric conversion element of the present invention, depending on the configuration of the semiconductor layer 7 and the electrolyte layer 13 to be used. At least an electrode having a semiconductor layer deposited on one surface;
In a photoelectric conversion element having a counter electrode facing the semiconductor layer of the electrode and an electrolyte layer disposed between the semiconductor layer and the counter electrode of the electrode, (1) the semiconductor layer is formed of a conductive material and a semiconductor. (2) disposing a layer made of conductive fine particles between the electrode and the semiconductor layer; (3) forming the semiconductor layer from a conductive substance and a semiconductor material; and A layer made of conductive fine particles is provided between the electrode and the semiconductor layer; (4) the electrolyte layer is composed of a porous support and an electrolyte filled in the porous support; (5) The semiconductor layer is composed of a conductive substance and a semiconductor material, and the electrolyte layer is composed of a porous support and an electrolyte filled in the porous support; Disposing a layer made of conductive fine particles between the electrode and the semiconductor layer, and The decomposition layer is composed of a porous support and an electrolyte filled in the porous support; (7) the semiconductor layer is composed of a conductive substance and a semiconductor material, and the electrode and the semiconductor layer are And a layer made of conductive fine particles is disposed between the porous support and the electrolyte layer. The electrolyte layer is composed of a porous support and an electrolytic solution filled in the porous support. In any of the above embodiments, the semiconductor layer is preferably of a type carrying a sensitizing dye.

FIG. 7 is a partially enlarged sectional view showing the embodiment (7).

[0093]

In the following, as a means for reducing the loss occurring in the semiconductor by the examples, the conversion of the dye-sensitized solar cell is performed by replacing the semiconductor portion which does not contribute to the photoelectric conversion with a material having a small resistance loss and transmission loss. The configuration and effect of the photoelectric conversion device of the present invention with improved efficiency will be specifically illustrated.

Example 1 ITO particles (made by Mitsui Mining & Smelting, average particle size: 20 nm) were dispersed at a concentration of about 1 wt% in a mixed solution (volume mixing ratio = 20/1) of water and acetylacetone containing a surfactant. Thus, a slurry liquid was prepared. Next, this slurry liquid was applied to a thickness of 1 m.
m conductive glass substrate (F-SnO ₂ , 10Ω / sq,
Coated with Asahi Glass) and dried.
Bake at 0 ° C for 30 minutes in air, 10μ thick on substrate
m of porous ITO film was formed. Next, the porous ITO film was immersed together with the substrate in water containing 2.0 g / L of fluorotitanium ammonium and 1.2 g / L of boric acid, and was left at 25 ° C. for 3 hours. A film-like titanium oxide film (thickness: 10 nm) was formed on the film. Then, a conductive glass having a titanium oxide thin film on a porous conductive film is converted into a sensitizing dye represented by [Ru (4,4′-dicarboxyl-2,2′-bipyridine) ₂ (NCS) ₂ ] 8 in the solution
The dye adsorption treatment was performed while refluxing at 0 ° C.

The semiconductor electrode obtained as described above and its counter electrode were brought into contact with an electrolyte solution to form a solar cell. In this case, as a counter electrode, conductive glass in which platinum was deposited to a thickness of 20 nm was used. The distance between both electrodes was 0.1 mm. As the electrolyte solution, a mixed solution of ethylene carbonate containing tetrapropylammonium iodide (0.5M) and iodine (0.04M) and acetonitrile (volume mixing ratio = 80/20) was used.

The conversion efficiency of the battery obtained as described above is summarized in Table 1 below. Also, in Table 1 below,
The element ratio of the metal element present in the semiconductor material to the metal element present in the conductive substance and the resistivity and transmittance of the semiconductor layer are also shown.

Comparative Example 1 Titanium oxide particles (P25, manufactured by Nippon Aerosil Co., Ltd., average particle size: 20 nm) were mixed in a mixed solution of water containing a surfactant and acetylacetone (volume mixing ratio = 20/1) at a concentration of about 1 wt%. To prepare a slurry liquid. Next, this slurry liquid was applied to a conductive glass substrate (F-SnO, manufactured by Asahi Glass Co., Ltd.)
The resultant was dried at 500 ° C. for 30 minutes in air to form a 10 μm-thick porous titanium oxide film on the substrate. Next, along with the substrate provided with the porous titanium oxide film, [Ru (4,
4'-dicarboxyl-2,2'-bipyridine) 2 (NCS) 2], and the dye was adsorbed while refluxing at 80 ° C.

A solar cell was constructed by bringing the semiconductor electrode obtained as described above and its counter electrode into contact with an electrolyte solution. In this case, as a counter electrode, conductive glass in which platinum was deposited to a thickness of 20 nm was used. The distance between both electrodes was 0.1 mm. As the electrolyte solution, a mixed solution of ethylene carbonate containing tetrapropylammonium iodide (0.5 M) and iodine (0.04 M) and acetonitrile (volume mixing ratio = 80/20) was used. The conversion efficiency of the battery obtained as described above is summarized in Table 1 below. Table 1 below also shows the element ratio of the metal element in the semiconductor material to the metal element in the conductive substance, and the resistivity and transmittance of the semiconductor layer.

[0099]

TABLE 1 semiconductor layer resistivity light transmission conversion efficiency element ratio of metal elements in the material of the semiconductor semiconductor layer 500nm to the metal element of the conductive material in (Y / X) (Ω- cm) ratio (%) ( %) Example 1 0.53 0.2 × 10 ⁴ 80 7.3 Comparative Example 1 78.0 0.1 × 10 ⁶ 65 3.2 (Note) The reason for writing the value of Y / X in Comparative Example 1 is that the semiconductor layer 7 on the transparent electrode 5 is separated from the electrode. This is because, at the time of separation, only the semiconductor layer 7 cannot be completely removed, and a very small amount of the transparent electrode component (tin oxide) is mixed. Therefore, in Comparative Example 1, ideally X = 0 and Y / X = infinity, but in reality, the X component is detected and Y / X has a finite value. Becomes

As is clear from the results shown in Table 1 above, the photoelectric conversion element of Example 1 according to the present invention was obtained in Comparative Example 1
Higher output characteristics can be obtained as compared with the conventional photoelectric conversion element.

Example 2 (1) Preparation of titanium particles coated with titanium oxide 60 g of titanium tetraisopropoxide was added to 2-propanol 3
The solution was gradually added to 00 ml to prepare a transparent titanium oxide sol solution. 10 g of ITO particles (Mitsui Metal Mining Co., Ltd., average particle size 20 nm)
Was dispersed in 100 ml of 2-propanol to prepare an ITO suspension. The ITO suspension was added at once to the sol solution of titanium oxide, and the mixture was vigorously stirred for 30 seconds. The reaction solution was filtered to separate ITO particles coated with titanium oxide. To remove excess titanium oxide, the separated particles were added to 200 ml of 2-propanol and stirred. Subsequently, after filtration, the particles were dried to obtain ITO particles coated with titanium oxide. When the obtained particles were observed by TEM, the average particle size was 40 nm, and ITO
It was estimated that the surface of the particles was coated with titanium oxide with an average film thickness of 10 nm. Further, as a result of examining the obtained particles by X-ray diffraction, the coated titanium oxide was of an anatase type.

(2) Preparation of Porous Titanium Oxide Film 2 ml of water and 0.2 ml of acetylacetone were added to 6 g of the titanium oxide-coated ITO particles prepared in the preceding section, and a paste was prepared using shear stress. This paste was dispersed in polyethylene glycol (molecular weight 400) in an agate mortar. The ratio of the paste to the polyethylene glycol is 30% by weight. Polyethylene glycol with titanium oxide-coated ITO particles dispersed in a screen plate (mesh 200, coating area 1 cm
^{In 2} ), screen printing was performed on a conductive glass substrate (F-SnO ₂ , 10Ω / sq, manufactured by Asahi Glass). Subsequently, the temperature of the substrate was raised to 450 ° C. over 3 hours, and baked at 450 ° C. for 1 hour. The steps of screen printing and firing were repeated twice to obtain a porous titanium oxide film having a thickness of 15 μm.

(3) Production of Photoelectric Conversion Element A transparent electrode of porous titanium oxide carrying a sensitizing dye was produced in the following procedure. A conductive glass substrate (10 mm x 20 mm) coated with the porous titanium oxide film prepared in the preceding section,
The sensitizing dye [Ru (4,4'-cyclicoxyl-2,2'-polyuricinyl) ₂ (N
CS) ₂ ] 50 ml of dehydrated ethanol in which 0.3 mM was dissolved was placed in a 100 ml eggplant-shaped flask, and the sensitizing dye was adsorbed while refluxing at 80 ° C. The conductive glass substrate was removed from the eggplant-shaped flask and washed with dehydrated ethanol to remove the sensitizing dye not carried on the porous titanium oxide film. Also, platinum on glass with transparent electrodes (10 mm x 20 mm)
This was used as a counter electrode by sputtering with a thickness of 20 nm. 0.5 mol of tetrapropylammonium iodide as electrolyte solution
A mixed solution (volume mixing ratio = 80/20) of ethylene carbonate and acetonitrile containing / 4 and 0.04 mol / l of iodine was used. The electrolyte was impregnated between the two electrodes by capillary action so that the titanium oxide side and the platinum side faced each other. Subsequently, the periphery was sealed, and a terminal was pulled out from each electrode to produce a photoelectric conversion element of the present invention.

The photoelectric conversion element of the present invention was irradiated with xenon lamp light of 45 mW / cm ² (irradiation area: 1 cm ² ), and the photocurrent-voltage characteristics were measured.

Example 3 (1) Preparation of Niobium Oxide-Coated SnO ₂ Particles After gradually adding 64 g of niobium (V) ethoxide to 400 ml of absolute ethanol, 7 ml of water was added to prepare a clear niobium oxide sol solution. . 10 g of SnO2 particles (Pastran TYPE-IV4700, manufactured by Mitsui Kinzoku Mining Co., Ltd., average particle diameter 100 nm) were dispersed in 100 ml of absolute ethanol to prepare a SnO2 suspension. The SnO2 suspension was added at once to the niobium oxide sol solution, and vigorously stirred for 30 seconds. The reaction solution was filtered to separate SnO2 particles coated with niobium oxide. To remove excess niobium oxide, the separated particles were added to 200 ml of absolute ethanol and stirred. Subsequently, after filtration, the powder was dried to obtain SnO2 particles coated with niobium oxide. When the obtained particles were observed by TEM, it was estimated that the average particle diameter was 130 nm, and that the surface of the SnO2 particles was coated with niobium oxide at an average film thickness of 15 nm.

(2) Preparation of Porous Niobium Oxide Film The niobium oxide-coated SnO 2 particles prepared in the preceding section were screen-printed on a conductive glass substrate in the same procedure as in Example 2. Subsequently, the temperature of the substrate was raised to 500 ° C. over 3 hours,
For 1 hour. The steps of screen printing and firing were repeated three times to obtain a porous niobium oxide film having a thickness of 36 μm.

(3) Preparation of Photoelectric Conversion Element A photoelectric conversion element having a porous niobium oxide transparent electrode carrying a Ru complex sensitizing dye as a component was prepared and evaluated in the same procedure as in Example 2. .

Example 4 60 g of titanium tetraisopropoxide was added to 2-propanol 30
After gradually adding to 0 ml, 7 ml of water and 0.5 g of polyethylene glycol having a molecular weight of 1000 were added to prepare a transparent titanium oxide sol solution. 10 g of SnO2 particles (Made by Mitsui Kinzoku Mining Co., Ltd., Pastran TYPE-IV4700, average particle diameter 100 nm) were dispersed in 100 ml of 2-propanol to prepare a SnO2 suspension. The SnO2 suspension was added at once to the sol solution of titanium oxide and stirred vigorously for 30 seconds. The reaction solution was filtered to separate SnO2 particles coated with titanium oxide. To remove excess titanium oxide and polyethylene glycol, the separated particles were added to 200 ml of absolute ethanol and stirred. Subsequently, after filtration, the powder was dried to obtain SnO ₂ particles coated with titanium oxide.
When the obtained particles were observed by SEM, the surface of the SnO2 particles was partially exposed due to the effect of polyethylene glycol, and a surface morphology not covered with titanium oxide was observed. The exposed portion of the surface was a pore having a diameter of 10 to 20 nm.
Using the SnO2 particles partially covered with titanium oxide, a porous titanium oxide film was prepared in the same procedure as in Example 2, and then a photoelectric conversion element was prepared and evaluated.

Comparative Example 2 Titanium oxide particles (manufactured by Nippon Aerosil Co., Ltd., P25, average particle diameter 20 nm) were mixed in a liquid mixture of water containing a surfactant and acetylacetone (volume mixing ratio = 20/1) at a concentration of about 38 wt.
% To prepare a slurry liquid. Next, this slurry liquid was applied to a conductive glass substrate having a thickness of 1 mm (manufactured by Asahi Glass Co., Ltd., F
—SnO 2, 10 Ω / sq) and dried. The obtained dried product was fired at 500 ° C. for 30 minutes in air to form a 10 μm thick porous titanium oxide film on the substrate.
Next, together with the substrate provided with the porous titanium oxide film,
[Ru (4,4'-dicarboxyl-2,2'-bipyridine) 2- (NCS)
2] and immersed in a sensitizing dye solution, and refluxed at 80 ° C. to perform dye adsorption treatment.

The photoelectric conversion element was constructed by interposing an electrolytic solution between the semiconductor electrode obtained as described above and its counter electrode.
In this case, as a counter electrode, conductive glass in which platinum was deposited to a thickness of 20 nm was used. As the electrolytic solution, a mixed solution of ethylene carbonate containing tetrapropylammonium iodide (0.46 M) and iodine (0.6 M) and acetonitrile (volume mixing ratio = 80/20) was used.

Table 2 below shows the evaluation results of the photoelectric conversion efficiency of each of the photoelectric conversion elements of Example 2, Example 3, Example 4, and Comparative Example 2.

[0112]

Table 2 specimen photoelectric conversion efficiency (%) Example 2 6.3 Example 3 5.9 Example 4 6.5 Comparative Example 2 5.2

As is evident from the results shown in Table 2, the photoelectric conversion efficiency of Example 2 was higher than that of Comparative Example 2. Further, as shown in Example 3, a photoelectric conversion element having high photoelectric conversion efficiency was able to be manufactured by using niobium oxide which is a metal oxide other than titanium oxide. Further, as shown in Example 4, by using SnO ₂ conductive particles having a part of the surface obtained by adding polyethylene glycol to a titanium oxide sol solution, the electrical conductivity between the conductive particles was improved. The contact was improved, and a higher conversion efficiency than that of Example 2 was obtained.

Next, in order to provide a photoelectric conversion element having a low resistance loss and a low transmission loss and capable of achieving a high photoelectric conversion rate, at least one of the electrodes having a semiconductor layer adhered on one surface is required. A photoelectric conversion element having a counter electrode facing the semiconductor layer of the electrode, and an electrolyte layer disposed between the semiconductor layer and the counter electrode of the electrode; A specific description will be given of an example of a photoelectric conversion element according to an example of the present invention in which it is effective to provide a fine particle layer.

Example 5 (1) Preparation of Layer Made of Conductive Fine Particles ITO particles (manufactured by Mitsui Mining & Smelting, average particle size) were mixed in a mixed solution (volume mixing ratio = 20/1) of water and acetylacetone containing a surfactant. (Diameter: 20 nm) was dispersed at a concentration of about 1 wt% to prepare a slurry liquid. Next, this slurry liquid was applied to a thickness of 1 m.
m glass substrate with conductive electrodes (10 mm x 20 mm, F
-SnO2, 10 Ω / sq, manufactured by Asahi Glass Co., Ltd.), dried, and fired at 500 ° C. for 30 minutes in air to form a 2 μm thick porous fine particle on a substrate. Layer was formed. At this time, the transmittance of the layer made of the conductive fine particles was about 80%.

(2) Preparation of Porous Titanium Oxide Film Titanium oxide (manufactured by Nippon Aerosil Co., Ltd., P25, average particle size 2)
0nm) 9g of water 21ml and acetylacetone 0.2m
was added to the suspension, and nitric acid was added to the suspension so as to maintain the pH at 1.5, followed by dispersion in an agate mortar for 3 hours. Thereafter, polyethylene glycol (molecular weight: 20,000) is added to prepare a paste. Polyethylene glycol is 30% by weight based on titanium oxide. The paste in which titanium oxide was dispersed was screen-printed on a glass substrate with a transparent electrode to which the ITO particles were applied, using a screen plate (200 mesh, application area: 1 cm 2). Subsequently, the substrate was placed in an electric furnace at 450 ° C. and baked at 450 ° C. for 30 minutes. Thus, a porous titanium oxide film having a thickness of 15 μm was obtained.

(3) Production of Photoelectric Conversion Element A transparent electrode of porous titanium oxide carrying a sensitizing dye was produced in the following procedure. Immediately after firing the glass substrate with a transparent electrode coated with the porous titanium oxide film prepared in the preceding section, the sensitizing dye [Ru (4,4'-cyclicoxyl-2,2'-silicone) 2 (NCS) 2] The mixture was placed in a 100 ml eggplant-shaped flask containing 50 ml of dehydrated ethanol in which 0.3 mM was dissolved, and the sensitizing dye was adsorbed while refluxing at 80 ° C. for 3 hours. The conductive glass substrate was removed from the eggplant-shaped flask and washed with dehydrated ethanol to remove the sensitizing dye not carried on the porous titanium oxide film. Also, platinum was sputtered on a glass with a transparent electrode (10 mm × 20 mm) to a thickness of 20 nm, and this was used as a counter electrode. The distance between both electrodes is 0.
1 mm. As an electrolyte solution, a mixed solution of ethylene carbonate and acetonitrile containing 0.5 mol / l of tetrapropylammonium iodide and 0.04 mol / l of iodine (volume mixing ratio = 80/20) was used. These two
The electrolyte solution was impregnated between the electrodes by capillary action so that the titanium oxide side and the platinum side faced one another.
Next, seal the periphery, pull out the terminal from each electrode,
The photoelectric conversion element of the present invention was produced. The thus obtained photoelectric conversion element of the present invention was irradiated with a xenon lamp light of 45 mW / cm 2 (irradiation area 1 cm ² ), and the photocurrent-voltage characteristics were measured.

Comparative Example 3 Titanium oxide (manufactured by Nippon Aerosil Co., Ltd., P25, average particle size 2)
(0 nm) was added to 100 ml of water, and nitric acid was added to the suspension to keep the pH at 1.5. After stirring, ITO particles (manufactured by Mitsui Kinzoku Mining Co., Ltd., average particle size: 20 nm) were mixed as a conductive material and dispersed in an agate mortar for 3 hours. Thereafter, polyethylene glycol (molecular weight 2000)
0) is added to produce a paste. Polyethylene glycol is 30% by weight based on the total amount of titanium oxide and ITO particles. A paste in which titanium oxide and ITO particles were dispersed was screen-printed on the glass substrate with a transparent electrode using a screen plate (200 mesh, application area 1 cm 2).
Subsequently, the substrate was placed in an electric furnace at 450 ° C.
For 30 minutes. Thus, a mixed film having a thickness of 15 μm was obtained.

Immediately after firing the glass substrate provided with the transparent electrode on which the mixed film was adhered, the sensitizing dye [Ru (4,4′-doxycarboxy-
2,2'-divinyl) ₂ (NCS) ₂ ] was placed in a 100 ml eggplant-shaped flask containing 50 ml of dehydrated ethanol in which 0.3 mM was dissolved, and the sensitizing dye was adsorbed while refluxing at 80 ° C. for 3 hours. Was. The conductive glass substrate was removed from the eggplant-shaped flask and washed with dehydrated ethanol to remove the sensitizing dye not carried on the mixed film. Also, platinum was sputtered on a glass with a transparent electrode (10 mm × 20 mm) to a thickness of 20 nm, and this was used as a counter electrode. The distance between both electrodes was 0.1 mm. As the electrolyte solution, 0.5 mol / l of tetrapropylammonium iodide and 0.04 of iodine were used.
A mixed solution of ethylene carbonate and acetonitrile containing mol / l (volume mixing ratio = 80/20) was used. The electrolyte was impregnated between the two electrodes by capillary action so that the titanium oxide side and the platinum side faced each other.
Next, seal the periphery, pull out the terminal from each electrode,
A photoelectric conversion element for comparison was produced. This comparative photoelectric conversion element was irradiated with xenon lamp light of 45 mW / cm 2 (irradiation area 1 cm ² ), and the photocurrent-voltage characteristics were measured.

Comparative Example 4 In a mixed solution of water containing a surfactant and acetylacetone (volume mixing ratio = 20/1), ITO particles (average particle size: 800 n) were used.
m) was dispersed at a concentration of about 1% by weight to prepare a slurry liquid. Next, this slurry liquid was applied to a glass substrate with a conductive electrode having a thickness of 1 mm (10 mm × 20 mm, F-SnO ² , 10Ω).
/ Sq, manufactured by Asahi Glass Co., Ltd.) and dried. The obtained dried product was fired in air at 500 ° C. for 30 minutes to form a 2 μm thick porous transparent conductive film on the substrate. At this time, the transmittance of the porous conductive film was 65%. Next, the titanium oxide paste of Example 1 was screen-printed,
It was baked at 50 ° C. for 30 minutes to obtain a porous semiconductor film. Immediately after firing, the substrate is a sensitizing dye [Ru (4,4'-doxycarboxy-2,2'-
_{Dipyridine) 2 (NCS) 2] 0.3mM} 80 ℃ in dehydrated ethanol 50ml of dissolved was subjected to adsorption treatment of a sensitizing dye while refluxing for 3 hours. The substrate was removed and washed with dehydrated ethanol to remove excess dye. On the other hand,
Glass with a transparent electrode on which platinum was deposited to a thickness of 20 nm was used. The distance between both electrodes was 0.1 mm. As an electrolyte solution, tetrapropyl ammonium iodide (0.5
M) and ethylene carbonate containing iodine (0.04M) and acetonitrile. The electrolyte was impregnated between the two electrodes by capillary action so that the titanium oxide side and the platinum side faced each other. Subsequently, the periphery was sealed, and a terminal was pulled out from each electrode to produce a photoelectric conversion element for comparison. 45 mW / c was applied to this photoelectric conversion element for comparison.
m ² xenon lamp light (irradiation area 1 cm ² )
Photocurrent-voltage characteristics were measured.

Comparative Example 5 ITO particles (manufactured by Mitsui Mining & Smelting, average particle size: 20 nm) were dispersed at a concentration of about 5 wt% in a mixed solution (volume mixing ratio = 20/1) of water and acetylacetone containing a surfactant. Thus, a slurry liquid was prepared. Next, this slurry liquid was applied to a
m glass substrate with conductive electrodes (10 mm x 20 mm, F
-SnO ₂ , 10Ω / sq, manufactured by Asahi Glass Co., Ltd.), dried, and fired at 500 ° C. for 30 minutes in air to form a 10 μm thick porous transparent conductive film on the substrate. Formed. At this time, the transmittance of the transparent conductive film was about 60%. Further, the titanium oxide paste in Example 1 was screen-printed and baked at 450 ° C. for 30 minutes to obtain a porous semiconductor film. After calcination, the porous semiconductor film adhered to dehydrated ethanol in which 0.3 mM of the sensitizing dye [Ru (4,4'-carboxyl-2,2'-dihydroxy) ₂ (NCS) ₂ ] was dissolved. The conductive glass substrate was put therein, and refluxed at 80 ° C. for 3 hours to perform a sensitizing dye adsorption treatment. The substrate was removed and washed with dehydrated ethanol to remove excess dye. As a counter electrode, glass with a transparent electrode on which platinum was deposited to a thickness of 20 nm was used.
The distance between both electrodes was 0.1 mm. As the electrolyte solution, tetrapropylammonium iodide (0.5
M) and ethylene carbonate containing iodine (0.04M) and acetonitrile. The electrolyte solution was impregnated between the two electrodes by capillary action so that the titanium oxide side and the platinum side faced each other. Subsequently, the periphery was sealed, and a terminal was pulled out from each electrode to produce a photoelectric conversion element for comparison. 45 mW /
cm ² xenon lamp light (irradiation area 1c
m ² ), and the photocurrent-voltage characteristics were measured.

Table 3 shows the evaluation results of the photoelectric conversion efficiencies of the respective photoelectric conversion elements in Example 5, Comparative Example 2, Comparative Example 3, Comparative Example 4, and Comparative Example 5 obtained as described above.

[0123]

TABLE 3 specimen photoelectric conversion efficiency (%) Example 5 6.4 Comparative Example 2 5.2 Comparative Example 3 5.4 Comparative Example 4 4.6 Comparative Example 5 5.3

As is evident from the results shown in Table 3 above, the photoelectric conversion element of Example 5 according to the present invention was obtained in Comparative Example 2
Higher photoelectric conversion efficiency than the conventional photoelectric conversion element of (1). Example 5 has a high photoelectric conversion by increasing the contact area between the titanium oxide and the ITO film without lowering the transmittance of the conductive film by interposing the porous ITO film between the titanium oxide and the transparent conductive film. Efficiency was obtained. In Comparative Example 3, a dye is carried on a mixed film containing a semiconductor and a conductive material to reduce the internal resistance in the semiconductor layer. However, the conductive material traps electrons, hinders electron transfer, and decreases the short-circuit current density. Will be. In Comparative Examples 4 and 5, Example 5 was used.
Similarly, although a porous ITO film is interposed, the ITO particles are large and the contact area is not sufficient, and the porous ITO film is thick and the light transmittance is reduced, so that the photoelectric conversion efficiency is reduced.

Next, in order to provide a photoelectric conversion element which does not leak and can maintain excellent photoelectric conversion efficiency for a long period of time, the electrolyte layer is made of a porous support, An example of the present invention, which is solved by being composed of an electrolyte solution filled in a support, will be specifically described with reference to examples.

Example 6 Titanium oxide particles (manufactured by Nippon Aerosil Co., Ltd., P25, average particle diameter: 20 nm) were mixed in a mixed solution of water containing a surfactant and acetylacetone (volume mixing ratio = 20/1) at a concentration of about 38 wt.
% To prepare a slurry liquid. Next, this slurry liquid was applied to a conductive glass substrate having a thickness of 1 mm (manufactured by Asahi Glass Co., Ltd., F
-SnO ₂ , 10Ω / sq) and dried. The obtained dried product was fired at 500 ° C. for 30 minutes in air to form a 10 μm thick porous titanium oxide film on the substrate.
Next, together with the substrate provided with the porous titanium oxide film,
[Ru (4,4'-dicarboxyl-2,2'-bipyridine) _2- (NCS)
₂ ], and the dye was adsorbed while refluxing at 80 ° C.

An electrolyte and a filtration filter (Whatman, 30% porosity) porous support having a columnar void having a pore diameter of 100 nm are sandwiched between the semiconductor electrode obtained as described above and its counter electrode. A conversion element was configured. In this case, as a counter electrode, conductive glass in which platinum was deposited to a thickness of 20 nm was used. The distance between the two electrodes, that is, the thickness of the filtration filter was 60 μm. As an electrolytic solution, tetrapropylammonium iodide (0.
46M) and a mixture of ethylene carbonate and acetonitrile containing iodine (0.6M) (volume mixing ratio = 80 /
20) was used.

Example 7 Titanium oxide particles (manufactured by Nippon Aerosil Co., Ltd., P25, average particle diameter: 20 nm) were mixed in a liquid mixture of water containing surfactant and acetylacetone (volume mixing ratio = 20/1) at a concentration of about 38 wt.
% To prepare a slurry liquid. Next, this slurry liquid was applied to a conductive glass substrate having a thickness of 1 mm (manufactured by Asahi Glass Co., Ltd., F
-SnO ₂ , 10Ω / sq) and dried. The obtained dried product was fired at 500 ° C. for 30 minutes in air to form a 10 μm thick porous titanium oxide film on the substrate.
Next, together with the substrate provided with the porous titanium oxide film,
[Ru (4,4'-dicarboxyl-2,2'-bipyridine) _2- (NCS)
₂ ], and the dye was adsorbed while refluxing at 80 ° C.

A porous support (porosity 40) having an electrolyte and a fibrous substance (mesh film) superposed between the semiconductor electrode obtained as described above and its counter electrode.
%) To form a photoelectric conversion element. In this case, as the counter electrode, a conductive glass on which platinum was deposited to a thickness of 20 nm was used. The distance between the two electrodes, that is, the thickness of the mesh film was 0.1 mm. As the electrolytic solution, a mixed solution of ethylene carbonate containing tetrapropylammonium iodide (0.46 M) and iodine (0.6 M) and acetonitrile (volume mixing ratio = 80/20) was used.

Comparative Example 6 Hexaethylene glycol methacrylate (Blenmer P manufactured by NOF Corporation) was used as a crosslinkable polymer monomer.
E350) 1 g, ethylene glycol 1 g as a substance capable of dissolving a redox couple, and 2-hydroxy-2-methyl-1-phenyl-propan-1-one (Darocur 117 manufactured by Ciba-Geigy Japan) as a polymerization initiator.
3) Add 50 mg of lithium iodide to the mixed solution containing 20 mg.
0 mg was dissolved and the mixed solution was applied on a semiconductor electrode. As the semiconductor electrode, titanium oxide particles (P25, manufactured by Nippon Aerosil Co., Ltd., average particle diameter: 20 nm) were mixed at a concentration of about 38 wt% in a mixed solution of water containing surfactant and acetylacetone (volume mixing ratio = 20/1). The slurry was dispersed to prepare a slurry liquid. Next, this slurry liquid was applied to a conductive glass substrate having a thickness of 1 mm (made by Asahi Glass, F-SnO ₂ , 10Ω / sq).
And dried at 500 ° C. for 30 minutes.
For 10 minutes in the air to form a porous titanium oxide film having a thickness of 10 μm on the substrate, and then, together with the substrate provided with the porous titanium oxide film, [Ru (4,4′-dicarboxyl- 2,
2′-bipyridine) _2- (NCS) ₂ ], and the dye was adsorbed while refluxing at 80 ° C. By placing the semiconductor electrode coated with the mixed solution under reduced pressure to remove bubbles in the porous semiconductor electrode and to promote penetration of the mixed solution, the polymer solid electrolyte having a crosslinked structure is polymerized by ultraviolet light irradiation. An electrode coated with a uniform gel was obtained. The electrode thus obtained was exposed to an iodine atmosphere for 30 minutes to diffuse iodine into the polymer compound, and then the counter electrode was pressed. As the counter electrode, a conductive glass in which platinum was deposited to a thickness of 20 nm was used.

Comparative Example 7 Titanium oxide particles (manufactured by Nippon Aerosil Co., Ltd., P25, average particle diameter: 20 nm) were mixed in a liquid mixture of water containing surfactant and acetylacetone (volume mixing ratio = 20/1) at a concentration of about 38 wt.
% To prepare a slurry liquid. Next, this slurry liquid was applied to a conductive glass substrate having a thickness of 1 mm (manufactured by Asahi Glass Co., Ltd., F
-SnO ₂ , 10Ω / sq) and dried. The obtained dried product was fired at 500 ° C. for 30 minutes in air to form a 10 μm thick porous titanium oxide film on the substrate.
Next, together with the substrate provided with the porous titanium oxide film,
[Ru (4,4'-dicarboxyl-2,2'-bipyridine) _2- (NCS)
₂ ], and the dye was adsorbed while refluxing at 80 ° C.

A porous support (mesh film, porosity 10%) in which an electrolyte and a fibrous substance are superposed between the semiconductor electrode obtained as described above and its counter electrode.
To form a photoelectric conversion element. In this case, as a counter electrode, conductive glass in which platinum was deposited to a thickness of 20 nm was used. The distance between the two electrodes, that is, the thickness of the mesh film was 0.1 mm. As an electrolyte, tetrapropylammonium iodide (0.46M) and iodine (0.
6M) and a mixture of ethylene carbonate and acetonitrile (volume mixing ratio = 80/20) was used.

Each of the photoelectric conversion devices manufactured as described above was evaluated for the difficulty of liquid leakage, the photoelectric conversion efficiency, and the long-term reliability by the following methods.

Regarding the possibility of occurrence of liquid leakage, the surface of the electrode was uniformly spread on the electrode surface along the normal direction of the electrode surface for one week at room temperature.
A pressure of kg / cm ² was applied, and thereafter, the presence or absence of liquid leakage was visually confirmed, and the determination was made using the result of the electrolyte retention test as an index.

Regarding the photoelectric conversion efficiency, the photoelectric conversion element was irradiated with a xenon lamp light of 45 mW / cm ^{2 and} the photocurrent was measured.
The voltage characteristics were measured, and the photoelectric conversion efficiency was determined.

Regarding long-term reliability, see JIS C8917.
The photoelectric conversion efficiency retention was determined from the photoelectric conversion efficiencies before and after the heat resistance (high temperature storage) test B-1 described in Appendix 9 and was used as an index to determine. In addition, JISC8917 Appendix 9
The method of the described heat resistance (high temperature storage) test B-1 is shown below.

Heat Resistance (High Temperature Storage) Test Method The heat resistance (high temperature storage) test includes the heat resistance (high temperature storage) test B- described in Annex 9 of the environmental test method and durability test method for the C8917 crystalline solar cell module. Performed according to 1.
The test method is described below. (1) Prior to the test, the photoelectric conversion efficiency of the sample is measured. (2) After heating from room temperature to 85 ° C. in a thermostat, the temperature is maintained at 85 ± 2 ° C. for 100 ± 12 hours. The output terminals in the test chamber are kept open. (3) After the test, the surface is cleaned with a clean cloth or the like, and then left at room temperature for 24 hours or more to evaluate the photoelectric conversion efficiency of the sample. (4) From the values of the photoelectric conversion efficiencies before and after the test, a photoelectric conversion efficiency retention rate defined by the following equation was determined. (Photoelectric conversion efficiency retention rate) = {(Photoelectric conversion efficiency before heat resistance test) − (Photoelectric conversion efficiency after heat resistance test)} × 100 /
(Photoelectric conversion efficiency before heat resistance test)

The electrolyte solution retention test results, photoelectric conversion efficiency and photoelectric conversion efficiency retention of Examples 5, 6 and Comparative Examples 2 to 4 are summarized in Table 1 below.

[0139]

[Table 4]

As is clear from the results shown in Table 4, the photoelectric conversion elements of the present invention in Examples 6 and 7 have no electrolyte leakage and are equivalent to the case where the electrolyte layer is composed of a liquid. The following photoelectric conversion characteristics were obtained. In particular, when the filtration filter having columnar voids shown in Example 6 is used as a porous support, a high photoelectric conversion efficiency can be obtained because the porous support has a small effect of inhibiting movement of a redox couple. On the other hand, the photoelectric conversion element of Comparative Example 2 has high initial characteristics, but has leakage of the electrolytic solution, and is inferior to the photoelectric conversion element of the present invention in terms of long-term reliability. The photoelectric conversion elements of Comparative Examples 6 and 7 are comparable to the photoelectric conversion elements of the present invention in that there is no electrolyte leakage, but the electrodes are formed of a uniform gel of a solid polymer electrolyte having a crosslinked structure. Since the electrolyte is covered or the electrolyte is held by a porous material having a small porosity, the electron transfer reaction via an oxidation-reduction pair is rate-determined, and the photoelectric conversion efficiency is reduced. In this respect, it is significantly inferior to the photoelectric conversion element of the present invention. Therefore, from these results, by providing a porous support having a porosity of 30% to 80% between the semiconductor layer and the counter electrode, high photoelectric conversion efficiency and a long period of time can be obtained without causing electrolyte leakage. It can be understood that a photoelectric conversion element having excellent reliability can be obtained.

Example 8 (1) Preparation of Layer Made of Conductive Fine Particles ITO particles (manufactured by Mitsui Mining & Smelting, average particle size) were mixed in a mixed solution (volume mixing ratio = 20/1) of water and acetylacetone containing a surfactant. (Diameter: 20 nm) was dispersed at a concentration of about 1 wt% to prepare a slurry liquid. Next, this slurry liquid was applied to a
m glass substrate with conductive electrodes (10 mm x 20 mm, F
-SnO ₂ , 10Ω / sq, manufactured by Asahi Glass Co., Ltd.), dried, and fired at 500 ° C. for 30 minutes in air to form porous transparent fine particles having a thickness of 2 μm on a substrate. Was formed. At this time, the transmittance of the layer made of the conductive fine particles was about 80%.

(2) Preparation of titanium particles coated with titanium oxide 60 g of titanium tetraisopropoxide was gradually added to 300 ml of 2-propanol to prepare a transparent sol solution of titanium oxide. 10 g of ITO particles (manufactured by Mitsui Kinzoku Mining Co., Ltd., average particle size: 20 nm) were dispersed in 100 ml of 2-propanol to prepare an ITO suspension. The ITO suspension was added at once to the sol solution of titanium oxide, and stirred vigorously for 30 seconds. The reaction solution was filtered to separate the ITO particles coated with titanium oxide. To remove excess titanium oxide, the separated particles were added to 200 ml of 2-propanol and stirred. Subsequently, after filtration, the particles were dried to obtain ITO particles coated with titanium oxide. When the obtained particles were observed by TEM, it was estimated that the average particle diameter was 40 nm, and that the surface of the ITO particles was covered with titanium oxide with an average film thickness of 10 nm. Further, as a result of examining the obtained particles by X-ray diffraction, the coated titanium oxide was of an anatase type.

To 6 g of the titanium oxide-coated ITO particles prepared in the preceding paragraph, 2 ml of water and 0.2 ml of acetylacetone were added, and a paste was prepared by utilizing shear stress. This paste was dispersed in polyethylene glycol (molecular weight 400) in an agate mortar. The ratio of paste to polyethylene glycol is 30% by weight. Titanium oxide coating I
Conductive glass substrate (F-SnO ₂ , 10Ω / sq, manufactured by Asahi Glass) on a screen plate (mesh 200, coating area 1 cm ² ) of polyethylene glycol in which TO particles are dispersed.
Screen printing was performed on the layer of conductive particles formed thereon. Subsequently, the temperature of the substrate was raised to 450 ° C. over 3 hours, and baked at 450 ° C. for 1 hour. The steps of screen printing and firing were repeated twice to obtain a porous titanium oxide film having a thickness of 15 μm.

(3) Preparation of Photoelectric Conversion Element A transparent electrode of porous titanium oxide carrying a sensitizing dye was prepared in the following procedure. A conductive glass substrate (10 mm × 20 m) coated with the porous titanium oxide film prepared in the previous section.
m) and 0.3 mM of a sensitizing dye [Ru (4,4'-carboxyl-2,2'-dihydroxy) ₂ (NCS) ₂ ] in 50 ml of dehydrated ethanol.
The mixture was placed in a 100 ml eggplant-shaped flask and subjected to adsorption treatment of a sensitizing dye while refluxing at 80 ° C. The conductive glass substrate was removed from the eggplant-shaped flask and washed with dehydrated ethanol to remove the sensitizing dye not carried on the porous titanium oxide film. Also, platinum was sputtered on a glass with a transparent electrode (10 mm × 20 mm) to a thickness of 20 nm, and this was used as a counter electrode. As the electrolyte solution, a mixed solution of ethylene carbonate and acetonitrile containing 0.5 mol / l of tetrapropylammonium iodide and 0.04 mol / l of iodine (volume mixing ratio = 80/20) was used. The electrolyte was impregnated between the two electrodes by capillary action so that the titanium oxide side and the platinum side faced each other. Subsequently, the periphery was sealed, and a terminal was pulled out from each electrode to produce a photoelectric conversion element of the present invention.

The photoelectric conversion device of the present invention has a capacity of 45 mW / cm ^2.
Was irradiated (irradiation area: 1 cm ² ), and the photocurrent-voltage characteristics were measured. The results are shown in Table 5 below.

[0146]

Table 5 specimen photoelectric conversion efficiency (%) Example 8 6.7

As is clear from comparison of the photoelectric conversion efficiency data shown in Table 5 with the photoelectric conversion efficiency data shown in Tables 1 to 4, at least one of the surfaces is covered with a semiconductor layer. A photoelectric conversion element comprising an electrode, a counter electrode facing the semiconductor layer of the electrode, and an electrolyte layer disposed between the semiconductor layer and the counter electrode of the electrode.
A structure in which a sensitizing dye is supported on a semiconductor film on a conductive material; and 2) a conductive fine particle layer is provided between the electrode and the semiconductor layer. Conversion efficiency is obtained.

Example 9 (1) Preparation of ITO Particles Coated with Titanium Oxide 60 g of titanium tetraisopropoxide was gradually added to 300 ml of 2-propanol to prepare a transparent titanium oxide sol solution. 10 g of ITO particles (manufactured by Mitsui Kinzoku Mining Co., Ltd., average particle size: 20 nm) were dispersed in 100 ml of 2-propanol to prepare an ITO suspension. The ITO suspension was added at once to the sol solution of titanium oxide, and stirred vigorously for 30 seconds. The reaction solution was filtered to separate the ITO particles coated with titanium oxide. To remove excess titanium oxide, the separated particles were added to 200 ml of 2-propanol and stirred. Subsequently, after filtration, the particles were dried to obtain ITO particles coated with titanium oxide. When the obtained particles were observed by TEM, it was estimated that the average particle diameter was 40 nm, and that the surface of the ITO particles was covered with titanium oxide with an average film thickness of 10 nm. Further, as a result of examining the obtained particles by X-ray diffraction, the coated titanium oxide was of an anatase type.

To 6 g of the titanium oxide-coated ITO particles prepared in the preceding section, 2 ml of water and 0.2 ml of acetylacetone were added, and a paste was prepared using shear stress. This paste was dispersed in polyethylene glycol (molecular weight 400) in an agate mortar. The ratio of paste to polyethylene glycol is 30% by weight. Titanium oxide coating I
Conductive glass substrate (F-SnO ₂ , 10Ω / sq, manufactured by Asahi Glass) on a screen plate (mesh 200, coating area 1 cm ² ) of polyethylene glycol in which TO particles are dispersed.
Screen printing was performed on the layer of conductive particles formed thereon. Subsequently, the temperature of the substrate was raised to 450 ° C. over 3 hours, and baked at 450 ° C. for 1 hour. The steps of screen printing and firing were repeated twice to obtain a porous titanium oxide film having a thickness of 15 μm.

(2) Production of Photoelectric Conversion Element A transparent electrode of porous titanium oxide carrying a sensitizing dye was produced by the following procedure. A conductive glass substrate (10 mm × 20 m) coated with the porous titanium oxide film prepared in the previous section.
m) and 0.3 mM of a sensitizing dye [Ru (4,4'-carboxyl-2,2'-dihydroxy) ₂ (NCS) ₂ ] in dehydrated ethanol 5
0 ml was placed in a 100 ml eggplant-shaped flask, and the sensitizing dye was adsorbed while refluxing at 80 ° C. The conductive glass substrate was removed from the eggplant-shaped flask and washed with dehydrated ethanol to remove the sensitizing dye not carried on the porous titanium oxide film. Also, platinum was sputtered on a glass with a transparent electrode (10 mm × 20 mm) to a thickness of 20 nm, and this was used as a counter electrode. As the electrolyte solution, a mixed solution of ethylene carbonate and acetonitrile containing 0.5 mol / l of tetrapropylammonium iodide and 0.04 mol / l of iodine (volume mixing ratio = 80/20) was used. Between the semiconductor electrode obtained as described above and its counter electrode, an electrolytic solution and a filtration filter having a columnar void having a pore diameter of 100 nm (Whatman Corp., Porosity 30)
%) A photoelectric conversion element was produced by sandwiching a porous support.

Example 10 (1) Preparation of Layer Made of Conductive Fine Particles ITO particles (manufactured by Mitsui Mining & Smelting, average particle size) were mixed in a mixed solution (volume mixing ratio = 20/1) of water and acetylacetone containing a surfactant. (Diameter: 20 nm) was dispersed at a concentration of about 1 wt% to prepare a slurry liquid. Next, this slurry liquid was applied to a
m glass substrate with conductive electrodes (10 mm x 20 mm, F
-SnO ₂ , 10Ω / sq, manufactured by Asahi Glass Co., Ltd.), dried, and fired at 500 ° C. for 30 minutes in air to form porous transparent fine particles having a thickness of 2 μm on a substrate. Was formed. At this time, the transmittance of the layer made of the conductive fine particles was about 80%.

(2) Preparation of Porous Titanium Oxide Film Titanium oxide (manufactured by Nippon Aerosil Co., Ltd., P25, average particle size 2)
0nm) 9g of water 21ml and acetylacetone 0.2m
was added to the suspension, and nitric acid was added to the suspension so as to maintain the pH at 1.5, followed by dispersion in an agate mortar for 3 hours. Thereafter, polyethylene glycol (molecular weight: 20,000) is added to prepare a paste. Polyethylene glycol is 30% by weight based on titanium oxide. The paste in which titanium oxide was dispersed was screen-printed on a glass substrate with a transparent electrode to which the ITO particles had been applied, using a screen plate (200 mesh, application area: 1 cm ² ). Subsequently, the substrate was placed in an electric furnace at 450 ° C. and baked at 450 ° C. for 30 minutes. As a result, a porous titanium oxide film having a thickness of 15 μm was obtained.

(3) Production of Photoelectric Conversion Element A transparent electrode of porous titanium oxide carrying a sensitizing dye was produced by the following procedure. A conductive glass substrate (10 mm × 20 m) coated with the porous titanium oxide film prepared in the previous section.
m) and 0.3 mM of a sensitizing dye [Ru (4,4'-carboxyl-2,2'-dihydroxy) ₂ (NCS) ₂ ] in dehydrated ethanol 5
0 ml was placed in a 100 ml eggplant-shaped flask, and the sensitizing dye was adsorbed while refluxing at 80 ° C. The conductive glass substrate was removed from the eggplant-shaped flask and washed with dehydrated ethanol to remove the sensitizing dye not carried on the porous titanium oxide film. Also, platinum was sputtered on a glass with a transparent electrode (10 mm × 20 mm) to a thickness of 20 nm, and this was used as a counter electrode. As the electrolyte solution, a mixed solution of ethylene carbonate and acetonitrile containing 0.5 mol / l of tetrapropylammonium iodide and 0.04 mol / l of iodine (volume mixing ratio = 80/20) was used. Between the semiconductor electrode obtained as described above and its counter electrode, an electrolytic solution and a filtration filter having a columnar void having a pore diameter of 100 nm (Whatman Corp., Porosity 30)
%) A photoelectric conversion element was produced by sandwiching a porous support.

The xenon lamp light of 45 mW / cm ² (irradiation area 1 cm ² ) was applied to the photoelectric conversion elements of the present invention produced in the above Examples 9 and 10 to evaluate the photoelectric conversion efficiency. In addition, liquid leakage and long-term reliability were evaluated as described above. The results are summarized in Table 6 below.

[0155]

[Table 6] electrolyte solution holding photoelectric conversion efficiency photoelectric conversion efficiency specimen test result (%) Retention (%) Example 9 leakage without 6.3 99 Example 10 leakage without 6.3 99

As shown in Table 6 above, at least an electrode having a semiconductor layer attached on one surface, a counter electrode facing the semiconductor layer of this electrode, and a pair of the electrode and the semiconductor layer. In a photoelectric conversion element having an electrolyte layer disposed between the electrode and an electrode, 1) a structure in which a sensitizing dye is supported on a semiconductor film on a conductive material; 2) the electrolyte layer is formed of a porous support; By comprising the body and the electrolytic solution filled in the porous support, a photoelectric conversion element having high photoelectric conversion efficiency, no liquid leakage, and excellent in long-term reliability can be provided.

As shown in Table 6, at least one electrode having a semiconductor layer attached on one surface, a counter electrode facing the semiconductor layer of the electrode, and a pair of the electrode and the semiconductor layer. In a photoelectric conversion element having an electrolyte layer disposed between the electrode and an electrode, 1) disposing a conductive fine particle layer between the electrode and the semiconductor layer; and 2) forming the electrolyte layer on a porous support. By using both the electrolyte solution and the electrolyte solution filled in the porous support, a photoelectric conversion element having high photoelectric conversion efficiency, no liquid leakage, and excellent long-term reliability can be provided. .

Example 11 (1) Preparation of Layer Made of Conductive Fine Particles ITO particles (manufactured by Mitsui Mining & Smelting, average particle size) were mixed in a mixed solution (volume mixing ratio = 20/1) of water and acetylacetone containing a surfactant. (Diameter: 20 nm) was dispersed at a concentration of about 1 wt% to prepare a slurry liquid. Next, this slurry liquid was applied to a
m glass substrate with conductive electrodes (10 mm x 20 mm, F
-SnO ₂ , 10Ω / sq, manufactured by Asahi Glass Co., Ltd.), dried, and fired at 500 ° C. for 30 minutes in air to form porous transparent fine particles having a thickness of 2 μm on a substrate. Was formed. At this time, the transmittance of the layer made of the conductive fine particles was about 80%.

(2) Preparation of titanium oxide-coated ITO particles 60 g of titanium tetraisopropoxide was gradually added to 300 ml of 2-propanol to prepare a transparent sol solution of titanium oxide. 10 g of ITO particles (manufactured by Mitsui Kinzoku Mining Co., Ltd., average particle size: 20 nm) were dispersed in 100 ml of 2-propanol to prepare an ITO suspension. The ITO suspension was added at once to the sol solution of titanium oxide, and stirred vigorously for 30 seconds. The reaction solution was filtered to separate the ITO particles coated with titanium oxide. To remove excess titanium oxide, the separated particles were added to 200 ml of 2-propanol and stirred. Subsequently, after filtration, the particles were dried to obtain ITO particles coated with titanium oxide. When the obtained particles were observed by TEM, it was estimated that the average particle diameter was 40 nm, and that the surface of the ITO particles was covered with titanium oxide with an average film thickness of 10 nm. Further, as a result of examining the obtained particles by X-ray diffraction, the coated titanium oxide was of an anatase type.

To 6 g of the titanium oxide-coated ITO particles prepared in the preceding paragraph, 2 ml of water and 0.2 ml of acetylacetone were added, and a paste was prepared by utilizing shear stress. This paste was dispersed in polyethylene glycol (molecular weight 400) in an agate mortar. The ratio of paste to polyethylene glycol is 30% by weight. Titanium oxide coating I
Conductive glass substrate (F-SnO ₂ , 10Ω / sq, manufactured by Asahi Glass Co., Ltd.) on a screen plate (mesh 200, coating area 1 cm 2) of polyethylene glycol in which TO particles are dispersed.
Screen printing was performed on the layer of conductive particles formed thereon. Subsequently, the temperature of the substrate was raised to 450 ° C. over 3 hours, and baked at 450 ° C. for 1 hour. The steps of screen printing and firing were repeated twice to obtain a porous titanium oxide film having a thickness of 15 μm.

(3) Production of Photoelectric Conversion Element A transparent electrode of porous titanium oxide carrying a sensitizing dye was produced by the following procedure. A conductive glass substrate (10 mm × 20 m) coated with the porous titanium oxide film prepared in the previous section.
m) and 0.3 mM of a sensitizing dye [Ru (4,4'-carboxyl-2,2'-dihydroxy) ₂ (NCS) ₂ ] in dehydrated ethanol 5
0 ml was placed in a 100 ml eggplant-shaped flask, and the sensitizing dye was adsorbed while refluxing at 80 ° C. The conductive glass substrate was removed from the eggplant-shaped flask and washed with dehydrated ethanol to remove the sensitizing dye not carried on the porous titanium oxide film. Also, platinum was sputtered on a glass with a transparent electrode (10 mm × 20 mm) to a thickness of 20 nm, and this was used as a counter electrode. As the electrolyte solution, a mixed solution of ethylene carbonate and acetonitrile containing 0.5 mol / l of tetrapropylammonium iodide and 0.04 mol / l of iodine (volume mixing ratio = 80/20) was used. Between the semiconductor electrode obtained as described above and its counter electrode, an electrolytic solution and a filtration filter having a columnar void having a pore diameter of 100 nm (Whatman Corp., Porosity 30)
%) A photoelectric conversion element was produced by sandwiching a porous support.

The photoelectric conversion device of the present invention has a capacity of 45 mW / cm ^2.
Was irradiated (irradiation area: 1 cm ² ), and the photoelectric conversion efficiency was evaluated. In addition, liquid leakage and long-term reliability were evaluated as described above. The results are shown in Table 7 below.

[0163]

Table 7 electrolyte solution holding photoelectric conversion efficiency photoelectric conversion efficiency specimen test result (%) Retention (%) Example 11 from leaking without 6.7 99

As shown in Table 7 above, at least an electrode having a semiconductor layer attached on one surface, a counter electrode facing the semiconductor layer of this electrode, and a pair of the electrode and the semiconductor layer. In a photoelectric conversion element having an electrolyte layer disposed between the electrode and the electrode, 1) a structure in which a sensitizing dye is supported on a semiconductor film on a conductive substance; 2) a space between the electrode and the semiconductor layer 3) having a high photoelectric conversion efficiency by forming the electrolyte layer from a porous support and an electrolytic solution filled in the porous support, and It is possible to provide a photoelectric conversion element having no leakage and excellent in long-term reliability.

[0165]

As described above, according to the present invention,
By using a semiconductor layer formed by depositing a semiconductor thin film on the outer surface of a conductive substance as a semiconductor layer of a photoelectric conversion element, a photoelectric conversion element with low resistance loss and low transmission loss can be obtained. it can. Further, according to the present invention, by interposing a layer made of conductive particles between the semiconductor layer of the photoelectric conversion element and the transparent electrode, the contact area between the semiconductor layer and the transparent electrode is increased, and The resistance loss at the interface between the electrodes can be reduced, and a photoelectric conversion element having excellent photoelectric conversion efficiency can be obtained. Further, according to the present invention, by providing a porous support holding an electrolytic solution between a semiconductor layer and a counter electrode, a photoelectric conversion element excellent in long-term reliability that does not cause leakage of the electrolytic solution is obtained. be able to.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an example of a photoelectric conversion element of the present invention using a semiconductor layer formed by depositing a semiconductor thin film on an outer surface of a conductive substance.

FIG. 2 is a partially enlarged schematic cross-sectional view of another example of the photoelectric conversion element of the present invention using a semiconductor layer formed by depositing a semiconductor thin film on the outer surface of a conductive substance.

3A and 3B are schematic cross-sectional views illustrating transmission loss and resistance loss in each semiconductor layer of a conventional photoelectric conversion element and a photoelectric conversion element of the present invention, wherein FIG. 3A is a conventional photoelectric conversion element, and FIG. 3) is a photoelectric conversion element of the present invention using a semiconductor layer formed by depositing a semiconductor thin film on the outer surface of a conductive substance.

FIG. 4 is a partially enlarged schematic cross-sectional view of an example of the photoelectric conversion element of the present invention in which a layer made of conductive particles is interposed between a semiconductor layer and a transparent electrode.

FIG. 5 is a book in which a layer made of conductive particles is interposed between a semiconductor layer formed by depositing a semiconductor thin film on the outer surface of a conductive substance as shown in FIG. 2 and a transparent electrode; 1 is a partially enlarged schematic cross-sectional view of an example of a photoelectric conversion element of the present invention.

FIG. 6 is a schematic cross-sectional view of an example of the photoelectric conversion element of the present invention in which a porous support holding an electrolytic solution is provided between a semiconductor layer and a counter electrode.

7 is a diagram showing a state in which a layer of conductive particles is interposed between a semiconductor layer formed by depositing a semiconductor thin film on the outer surface of a conductive substance as shown in FIG. 5 and a transparent electrode;
FIG. 3 is a partially enlarged schematic cross-sectional view of an example of the photoelectric conversion element of the present invention in which a porous support holding an electrolyte is provided between a semiconductor layer and a counter electrode.

[Explanation of symbols]

 Reference Signs List 1 photoelectric conversion element of the present invention 3, 11 transparent substrate 5 transparent electrode 7 semiconductor layer 9 counter electrode 13 electrolyte layer 15 conductive material layer 17 semiconductor film 19 sensitizing dye 21, 23 conductive particle 25 conductive particle layer 27 porous Support 100 Conventional photoelectric conversion element

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shoji Nishihara 1-1-88 Ushitora, Ibaraki City, Osaka Prefecture Inside Hitachi Maxell Co., Ltd. (72) Inventor Fumihiko Kishi 1-1-88 Ushitora, Ibaraki City, Osaka Hitachi Maxell F term (reference) 5F051 AA14 5H032 AA06 AS16 AS17 BB02 BB05 BB10 CC06 CC14 CC17 EE02 EE04 EE07 EE08 EE16 EE18 HH01 HH04 HH07 HH08

Claims (26)

[Claims] 1. An electrode having a semiconductor layer deposited on at least one surface thereof, a counter electrode facing the semiconductor layer of the electrode, and a electrode disposed between the semiconductor layer and the counter electrode of the electrode. A photoelectric conversion element having an electrolyte layer, wherein the semiconductor layer is composed of a conductive material and a semiconductor material. 2. The photoelectric conversion element according to claim 1, wherein the semiconductor layer is composed of a conductive material layer and a semiconductor material layer formed on a surface of the conductive material layer. . 3. The photoelectric conversion device according to claim 1, wherein the semiconductor layer is formed of a thin film of a semiconductor material coated on outer surfaces of particles of a conductive substance. 4. The photoelectric conversion device according to claim 1, wherein the semiconductor layer further supports a sensitizing dye. 5. The conductive substance is a metal element-containing compound, the semiconductor material is a metal element-containing compound, and an element of a metal element present in the semiconductor material with respect to a metal element present in the conductive substance. The ratio is 0.1 or more.
The photoelectric conversion element according to claim 1, wherein the value is 0 or less. 6. The photoelectric conversion device according to claim 1, wherein the conductive material is light-transmissive. 7. The photoelectric conversion device according to claim 6, wherein the light transmittance of the conductive material is 60% or more. 8. An electrode having a semiconductor layer attached on at least one surface, a counter electrode facing the semiconductor layer of the electrode, and a counter electrode disposed between the semiconductor layer and the counter electrode of the electrode. In the method for manufacturing a photoelectric conversion element having an electrolyte layer, the semiconductor layer, (a) applying a slurry liquid of a conductive substance on the electrode surface,
Drying, then sintering to form a conductive material layer; (b) forming a film of a semiconductor material on the surface of the conductive material layer obtained in the step (a). A method for manufacturing a photoelectric conversion element, comprising: 9. An electrode having a semiconductor layer attached to at least one surface thereof, a counter electrode facing the semiconductor layer of the electrode, and being disposed between the semiconductor layer and the counter electrode of the electrode. In the method for manufacturing a photoelectric conversion element having an electrolyte layer, the semiconductor layer, (i) a step of coating a semiconductor material on the outer surface of the conductive particles using a sol solution of a semiconductor material, (ii) the semiconductor Applying the conductive particles coated with a material to the electrodes, and then heating and sintering the electrodes. 10. The method according to claim 10, further comprising removing at least a part of the semiconductor film covering the conductive particles to expose a lower conductive particle outer surface between the steps (i) and (ii). The method for manufacturing a photoelectric conversion element according to claim 9, wherein: 11. An electrode having a semiconductor layer deposited on at least one surface, a counter electrode facing the semiconductor layer of the electrode, and a electrode disposed between the semiconductor layer and the counter electrode of the electrode. A photoelectric conversion element having an electrolyte layer, wherein a layer made of conductive fine particles is disposed between the electrode and the semiconductor layer. 12. The conductive fine particles having a particle size of 3 nm to 5 nm.
The photoelectric conversion device according to claim 11, wherein the thickness is within a range of 00 nm. 13. The conductive fine particles having a volume resistivity of 10
^-9Ω-cm-10 ⁷Characteristic within the range of Ω-cm
The photoelectric conversion element according to claim 11, wherein 14. The conductive fine particle layer has a thickness of 10 nm.
The photoelectric conversion device according to claim 11, wherein the photoelectric conversion device has a wavelength within a range from 3,000 nm to 3,000 nm. 15. The conductive fine particles are one or more crystalline metal oxide fine particles selected from the group consisting of tin oxide, zinc oxide, aluminum oxide, silicon oxide, indium trioxide and strontium trioxide, or a composite thereof. The photoelectric conversion element according to claim 11, wherein the photoelectric conversion element is an oxide fine particle. 16. The photoelectric conversion device according to claim 15, wherein the composite oxide fine particles are indium tin oxide (ITO). 17. An electrode having a semiconductor layer attached to at least one surface thereof, a counter electrode facing the semiconductor layer of the electrode, and being disposed between the semiconductor layer and the counter electrode of the electrode. A photoelectric conversion element having an electrolyte layer, wherein the electrolyte layer is composed of a porous support and an electrolytic solution filled in the porous support. 18. The porosity of the porous support is 3
2. The method according to claim 1, wherein the value is in the range of 0% to 80%.
8. The photoelectric conversion element according to 7. 19. The thickness of the porous support is from 1 μm to 1 μm.
The photoelectric conversion element according to claim 17, wherein the distance is within the range of mm. 20. The method according to claim 1, wherein the porous support comprises a filter, a separator or a nonwoven fabric.
20. The photoelectric conversion element according to any one of 7 to 19. 21. The photoelectric conversion device according to claim 20, wherein the filter is made of a material selected from the group consisting of glass fibers, polyolefins, and polyesters. 22. The separator or nonwoven fabric is a group consisting of polyolefins, polyesters, polyamides, polyphenylene sulfide, vinylon (copolymer of vinyl chloride and vinyl acetate), polyimide, vinylon (acetalized polyvinyl alcohol). The photoelectric conversion device according to claim 20, wherein the photoelectric conversion device is formed of at least one kind of material selected from the group consisting of: 23. An electrode having a dye-sensitized semiconductor layer adhered on at least one surface thereof, a counter electrode facing the dye-sensitized semiconductor layer of the electrode, and the dye-sensitized semiconductor layer of the electrode. Wherein the dye-sensitized semiconductor layer is formed of a conductive material and a semiconductor material, and the electrode and the dye-sensitized semiconductor layer A photoelectric conversion element, wherein a layer made of conductive fine particles is provided therebetween. 24. An electrode having a dye-sensitized semiconductor layer deposited on at least one surface, a counter electrode facing the dye-sensitized semiconductor layer of the electrode, and the dye-sensitized semiconductor layer of the electrode. And a photoelectric conversion element having an electrolyte layer disposed between the counter electrode, wherein the dye-sensitized semiconductor layer is made of a conductive material and a semiconductor material, and the electrolyte layer is a porous support and And a liquid electrolyte filled in the porous support. 25. An electrode having a dye-sensitized semiconductor layer deposited on at least one surface, a counter electrode facing the dye-sensitized semiconductor layer of the electrode, and the dye-sensitized semiconductor layer of the electrode. And a photoelectric conversion element having an electrolyte layer disposed between the counter electrode, wherein a layer made of conductive fine particles is disposed between the electrode and the dye-sensitized semiconductor layer, and the electrolyte layer is A photoelectric conversion element comprising: a porous support; and an electrolyte filled in the porous support. 26. An electrode having a dye-sensitized semiconductor layer applied on at least one surface thereof, a counter electrode facing the dye-sensitized semiconductor layer of the electrode, and the dye-sensitized semiconductor layer of the electrode. Wherein the dye-sensitized semiconductor layer is formed of a conductive material and a semiconductor material, and the electrode and the dye-sensitized semiconductor layer A layer made of conductive fine particles is disposed therebetween, and the electrolyte layer is constituted by a porous support and an electrolyte filled in the porous support. Conversion element.