JP2003092417A - Photoelectric conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid state pigment-sensitized photoelectric conversion element which is manufacturable cheaply and superior in photoelectric conversion efficiency. SOLUTION: A solar cell 1 shown in Fig. 2 is the so-called dry type solar cell having no need of an electrolyte. The cell 1 has a first electrode 3, a second electrode 6 facing the first electrode 3, an electron transport layer 4 located between them, a pigment layer D contacted to the transport layer 4, a hole transport layer 5 contacted to the pigment layer D between the transport layer 4 and the second electrode 6, and a barrier layer 8. They are disposed on a substrate 2. The upside of the first electrode 3 is smoothed to reduce its surface irregularities to a surface roughness Rmax of 0.05-1 μm. The cell 1 has the barrier layer 8 apart from the electron transport layer 4 to obtain a superior photoelectric conversion efficiency.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a photoelectric conversion element.

[0002]

2. Description of the Related Art Conventionally, as an environmentally friendly power source,
Solar cells (photoelectric conversion elements) using silicon have been attracting attention. Among the solar cells that use silicon, there are single-crystal silicon type solar cells that are used in artificial satellites, etc., but as practical ones, especially solar cells that use polycrystalline silicon and amorphous silicon are used. The solar cells that have been put into practical use have begun to be used for industrial and household purposes.

However, any of these solar cells using silicon has a high manufacturing cost, requires a large amount of energy for manufacturing, and is not necessarily an energy-saving power source.

JP-A-01-220380, JP-A-05-504023 and JP-A-06-511113
The dye-sensitized wet-type solar cell as disclosed in Japanese Patent Publication (KOKAI) uses an electrolytic solution having a high vapor pressure, and thus has a problem of volatilizing the electrolytic solution.

In addition, in order to make up for such drawbacks,
Presentation of complete solid-state dye-sensitized solar cell (K. Tennakone,
GRRA Kumara, IRM Kottegoda, KGU Wijiayan
tha, and VPS Perera: J. Phys. D: Appl. Phys. 31
(1998) 1492), but the p-type semiconductor layer is TiO 2.
There was a drawback that it penetrated through the _two layers and short-circuited with the counter electrode.

Further, the solar cell using CuI of this announcement has a problem that the generated current is lowered due to deterioration.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a solid-state dye-sensitized photoelectric conversion device which can be manufactured at low cost and has excellent photoelectric conversion efficiency.

[0008]

The above objects are achieved by the present invention described in (1) to (44) below.

(1) A first electrode, a second electrode facing the first electrode, a first electrode and a second electrode, and at least one of them. A partially porous electron transport layer, a dye layer in contact with the electron transport layer,
A photoelectric conversion device having a hole transport layer located between the electron transport layer and the second electrode, wherein a short circuit between the first electrode and the hole transport layer is prevented or A photoelectric conversion element having a barrier layer for suppressing, wherein a surface of the first electrode on the side of the electron transport layer is subjected to a smoothing treatment for reducing unevenness of the surface.

(2) A first electrode, a second electrode facing the first electrode, and a second electrode located between the first electrode and the second electrode. A partially porous electron transport layer, a dye layer in contact with the electron transport layer,
A photoelectric conversion device having a hole transport layer located between the electron transport layer and the second electrode, wherein a short circuit between the first electrode and the hole transport layer is prevented or A photoelectric conversion element having a barrier layer for suppressing, wherein the surface roughness R _max of the surface of the first electrode on the side of the electron transport layer is set to 0.05 to 1 μm.

(3) The average thickness of the barrier layer is H [μ
when the m], the photoelectric conversion element according to the above (2) which satisfies the H ≧ 1.1R _{ma x} the relationship.

(4) The surface roughness of the surface of the first electrode on the side of the electron transport layer is adjusted by performing a smoothing treatment to reduce irregularities on the surface. The photoelectric conversion element according to 2) or (3).

(5) The photoelectric conversion element as described in any one of (1) to (4) above, wherein the smoothing treatment is polishing treatment and / or etching treatment.

(6) The photoelectric conversion element as described in (5) above, wherein the polishing treatment is performed using a polishing liquid containing a polishing agent.

(7) The photoelectric conversion element as described in (5) or (6) above, wherein the etching treatment is wet etching treatment, plasma etching treatment, or sputter etching treatment.

(8) The photoelectric conversion element as described in any one of (1) to (7) above, wherein the barrier layer is formed by laminating on the smoothed surface.

(9) The photoelectric conversion device according to any one of (1) to (8), wherein the barrier layer is formed so that the porosity is smaller than the porosity of the electron transport layer. Conversion element.

(10) The porosity of the barrier layer is A
[%] And the porosity of the electron transport layer is B [%], the photoelectric conversion element according to the above (9), wherein B / A is 1.1 or more.

(11) The porosity of the barrier layer is 20.
The photoelectric conversion element according to the above (9) or (10), which is at most%.

(12) The photoelectric conversion device as described in any one of (1) to (11) above, wherein the thickness ratio of the barrier layer to the electron transport layer is 1:99 to 60:40.

(13) The photoelectric conversion element as described in any one of (1) to (12) above, wherein the barrier layer has an average thickness of 0.01 to 10 μm.

(14) The barrier layer has the same electrical conductivity as that of the electron transport layer, and the barrier layers (1) to (1).
The photoelectric conversion element according to any one of 3).

(15) The photoelectric conversion element as described in any one of (1) to (14) above, wherein the barrier layer is mainly composed of titanium oxide.

(16) The photoelectric conversion element as described in any one of (1) to (15) above, wherein the barrier layer is formed by a MOD method.

(17) The resistance value in the thickness direction of the entire barrier layer and the electron transport layer is 100 Ω / cm ^2.
The photoelectric conversion element as described in any one of (1) to (16) above.

(18) The photoelectric conversion element as described in any one of (1) to (17), wherein the barrier layer is located between the first electrode and the electron transport layer.

(19) The photoelectric conversion element as described in (18) above, wherein the interface between the barrier layer and the electron transport layer is unclear.

(20) The barrier layer and the electron transport layer are integrally formed as described above (18) or (19).
The photoelectric conversion element described in 1.

(21) The photoelectric conversion element as described in any one of (1) to (17) above, wherein a part of the electron transport layer functions as the barrier layer.

(22) The photoelectric conversion element as described in any one of (1) to (21) above, wherein the dye layer is a light-receiving layer that generates electrons and holes by receiving light.

(23) The photoelectric conversion element as described in any one of (1) to (22) above, wherein the dye layer is formed along the outer surface of the electron transport layer and the inner surface of the pores.

(24) The photoelectric conversion element according to any one of (21) to (23), wherein the electron transport layer has a function of transporting electrons generated at least in the dye layer.

(25) The photoelectric conversion element as described in any one of (1) to (24) above, wherein the electron transport layer is in the form of a film.

(26) The photoelectric conversion device according to any one of (1) to (25), wherein the electron transport layer has an average thickness of 0.1 to 300 μm.

(27) The porosity of the electron transport layer is 5
The photoelectric conversion device according to any one of (1) to (26) above, wherein the photoelectric conversion device has a content of ˜90%.

(28) At least a part of the electron transport layer is formed by using a powder of an electron transport layer material having an average particle diameter of 1 nm to 1 μm.
The photoelectric conversion element according to any one of 7).

(29) At least a part of the electron transport layer is formed by a sol-gel method using a sol solution containing a powder of an electron transport layer material having an average particle size of 1 nm to 1 μm. The photoelectric conversion device according to any one of 1) to (28).

(30) The photoelectric conversion device as described in (29) above, wherein the content of the powder of the electron transport layer material in the sol liquid is 0.1 to 10% by weight.

(31) The photoelectric conversion element as described in any one of (1) to (30) above, wherein the electron transport layer is mainly composed of titanium dioxide.

(32) The photoelectric conversion element as described in any one of (1) to (31) above, wherein the hole transport layer is mainly composed of a substance having ionic conduction characteristics.

(33) The photoelectric conversion device according to the above (32), wherein the substance having the ion conductive property is a metal halide compound.

(34) The metal halide compound is
The photoelectric conversion device according to (33), which is a metal iodide compound.

(35) The hole transport layer is formed by coating a material for the hole transport layer containing a substance having the ion conductive property on the dye layer by a coating method. The photoelectric conversion element according to any one of (1) to (34).

(36) While heating the dye layer, the hole transport layer material is coated on the dye layer.
The photoelectric conversion element according to 5).

(37) The hole transport layer material contains a substance for improving hole transport efficiency (3).
5) The photoelectric conversion element described in (36).

(38) The photoelectric conversion element as described in (37) above, wherein the substance is a halide.

(39) The photoelectric conversion element as described in (38) above, wherein the halide is ammonium halide.

(40) The photoelectric conversion device as described in any of (37) to (39) above, wherein the content of the substance in the hole transport layer material is 10 ⁻⁴ to 10 ⁻¹ wt%.

(41) The photoelectric conversion element as described in any one of (1) to (40) above, which has a substrate supporting the first electrode.

(42) The first electrode is positive and the second electrode is positive.
5. The photoelectric conversion element as described in any one of (1) to (41) above, which has a characteristic that the resistance value becomes 100 Ω / cm ² or more when a voltage of 0.5 V is applied so that the electrode becomes negative. .

(43) The incident angle of light on the dye layer is 9
The photoelectric conversion efficiency at 0 ° is R _90, and the incident angle of light is 52
When the photoelectric conversion efficiency in ° is R ₅₂ , R ₅₂ / R
₉₀ is 0.8 or more, The photoelectric conversion element in any one of said (1) thru | or (42).

(44) The photoelectric conversion device as described in any one of (1) to (43) above, which is a solar cell.

[0053]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the photoelectric conversion device of the present invention shown in the accompanying drawings will be described in detail below.

FIG. 1 is a partial sectional view showing an embodiment in which the photoelectric conversion element of the present invention is applied to a solar cell, and FIG.
An enlarged view showing a cross section near the central portion in the thickness direction of the solar cell,
FIG. 3 is a partially enlarged view showing a cross section of the electron transport layer on which the dye layer is formed, FIG. 4 is a schematic view showing the configurations of the electron transport layer and the dye layer, and FIG. 5 is a schematic view showing the principle of the solar cell. , Fig. 6
[Fig. 2] is a diagram showing an equivalent circuit of the solar cell circuit shown in Fig. 1.

The solar cell 1 shown in FIG. 1 is a so-called dry type solar cell which does not require an electrolyte solution, and is composed of a first electrode 3 and a second electrode which is installed opposite to the first electrode 3. Electrode 6 and electron transport layer 4 located between them
A dye layer D that is in contact with the electron transport layer 4, and an electron transport layer 4
And a second electrode 6, and has a hole transport layer 5 in contact with the dye layer D, and a barrier layer 8, which are formed on the substrate 2
It is installed on top.

Each component will be described below. In the following description, the upper surface of each layer (each member) is referred to as the “upper surface” and the lower surface is referred to as the “lower surface” in FIGS. 1 and 2.

The substrate 2 is for supporting the first electrode 3, the barrier layer 8, the electron transport layer 4, the dye layer D, the hole transport layer 5 and the second electrode 6, and is a flat plate member. It is composed of.

In the solar cell 1 of the present embodiment, as shown in FIG. 1, for example, light such as sunlight (hereinafter, simply referred to as “light”) is emitted from the side of the substrate 2 and the first electrode 3 described later. Is incident (irradiated) for use. For this reason,
Each of the substrate 2 and the first electrode 3 is preferably substantially transparent (colorless transparent, colored transparent or translucent). Thereby, the light can efficiently reach the dye layer D described later.

The constituent material of the substrate 2 is, for example,
Examples thereof include various glass materials, various ceramic materials, various plastic materials, various resin materials such as polycarbonate (PC), and various metal materials such as aluminum.

The average thickness of the substrate 2 is appropriately set depending on the material, application, etc., and is not particularly limited, but can be set as follows, for example.

When the substrate 2 is made of a hard material such as a glass material, its average thickness is 0.1 to 1.5 m.
It is preferably about m, and more preferably about 0.8 to 1.2 mm.

The substrate 2 is made of a flexible material such as polyethylene terephthalate (PET).
When the average thickness is 0.5 to 15
The thickness is preferably about 0 μm, more preferably about 10 to 75 μm. The substrate 2 may be omitted if necessary.

On the upper surface of the substrate 2, the first layered (flat plate)
Electrode 3 is installed. In other words, the first electrode 3
Is installed on the light receiving surface side of the electron transport layer 4 on which the dye layer D described later is formed so as to cover the light receiving surface.
The first electrode 3 receives the electrons generated in the dye layer D described later via the electron transport layer 4 and the barrier layer 8,
It is transmitted to the external circuit 100 connected to this.

As the constituent material of the first electrode 3, for example, indium tin oxide (ITO), fluorine-doped tin oxide (FTO), indium oxide (IO),
Examples thereof include metal oxides such as tin oxide (SnO ₂ ), metals such as aluminum, nickel, cobalt, platinum, silver, gold, copper, molybdenum, titanium and tantalum or alloys containing these, carbon, and the like. One of these
One kind or a combination of two or more kinds can be used.

The average thickness of the first electrode 3 is
It is appropriately set depending on the application and the like, and is not particularly limited, but for example, the following can be performed.

When the first electrode 3 is composed of the above metal oxide (transparent conductive metal oxide), the average thickness thereof is preferably about 0.05 to 5 μm, and 0.1
More preferably, it is about 1.5 μm.

When the first electrode 3 is made of the above metals, alloys containing them, or carbon, the average thickness thereof is preferably about 0.01 to 1 μm, and 0.03 is preferable. More preferably, it is about 0.1 μm.

The upper surface of the first electrode 3 (the surface on the electron transport layer 4 side described later) has a surface texture (surface roughness).
Has been adjusted. This point will be described in detail after the barrier layer 8 is described.

The first electrode 3 is not limited to the one having the configuration shown in the figure, and may have a shape having a plurality of comb teeth, for example. In this case, since the light passes between the plurality of comb teeth and reaches the dye layer D, the first electrode 3 does not need to be substantially transparent. This allows
The range of selection of the constituent material of the first electrode 3 and the forming method (manufacturing method) can be expanded. Also, in this case, the first
The average thickness of the electrode 3 is not particularly limited, but is preferably about 1 to 5 μm, for example.

Further, as the first electrode 3, it is also possible to use such a comb-teeth-shaped electrode and a transparent electrode made of ITO, FTO or the like in combination (for example, by laminating).

On the upper surface of the first electrode 3, a film-shaped (layered) barrier layer (short-circuit preventing means) 8 is provided. In addition,
Details of the barrier layer 8 will be described later.

On the upper surface of the barrier layer 8, a porous electron transport layer 4 and a dye layer D which is in contact with the electron transport layer 4 are provided.

The electron transport layer 4 has a function of transporting at least electrons generated in the dye layer D.

Examples of the constituent material of the electron transport layer 4 include titanium dioxide (TiO ₂ ) and titanium monoxide (Ti).
O), titanium oxide such as dititanium trioxide (Ti ₂ O ₃ ),
N such as zinc oxide (ZnO) and tin oxide (SnO ₂ ).
-Type oxide semiconductor materials, other n-type semiconductor materials and the like can be mentioned, and one kind or a combination of two or more kinds thereof can be used. Among them, titanium oxide,
In particular, it is preferable to use titanium dioxide. That is,
The electron transport layer 4 is preferably composed mainly of titanium dioxide.

Titanium dioxide is particularly excellent in electron transporting ability and highly sensitive to light, so that the electron transporting layer 4 itself can generate electrons. as a result,
In the solar cell 1, the photoelectric conversion efficiency (power generation efficiency) can be further improved.

Since the crystal structure of titanium dioxide is stable, the electron transport layer 4 mainly composed of titanium dioxide is used.
Then, even if it is exposed to a harsh environment, it has an advantage that it does not change (deteriorate) over time and stable performance can be continuously obtained for a long time.

Further, as the titanium dioxide, those having a crystal structure mainly composed of anatase type titanium dioxide, those mainly composed of rutile type titanium dioxide, and a mixture of anatase type titanium dioxide and rutile type titanium dioxide are used. It may be one of the main ones.

Titanium dioxide having an anatase type crystal structure has an advantage that electrons can be more efficiently transported.

When rutile type titanium dioxide and anatase type titanium dioxide are mixed, the rutile type titanium dioxide and the anatase type titanium dioxide are not particularly limited. It is preferably about 5:95, and more preferably about 80:20 to 20:80.

The electron transport layer 4 has a plurality of holes (pores) 41. FIG. 3 schematically shows a state where light is incident on the electron transport layer 4. As shown in FIG. 3, light passing through the barrier layer 8 (arrows in FIG. 3) is emitted by the electron transport layer 4
Of the electron transport layer 4 or is reflected in any direction in the hole 41 (diffuse reflection, diffusion, etc.). At this time, the light comes into contact with the dye layer D, and electrons and holes can be generated in the dye layer D with high frequency.

The porosity of the electron transport layer 4 is not particularly limited, but is preferably about 5 to 90%, more preferably about 15 to 50%, and more preferably 2
It is more preferably about 0 to 40%.

By setting the porosity of the electron transport layer 4 within such a range, the surface area of the electron transport layer 4 can be made sufficiently large. Therefore, the formation area (formation region) of the dye layer D (see below) formed along the outer surface of the electron transport layer 4 and the inner surface of the hole 41 can be sufficiently increased. Therefore, in the dye layer D, sufficient electrons can be generated and the electrons can be efficiently transferred to the electron transport layer 4. As a result, in the solar cell 1, the power generation efficiency (photoelectric conversion efficiency) can be further improved.

The electron transport layer 4 may have a relatively large thickness, but a film-shaped one is preferable.
This is advantageous because the solar cell 1 can be made thinner (smaller) and the manufacturing cost can be reduced.

In this case, the average thickness (film thickness) of the electron transport layer 4 is not particularly limited, but is, for example, 0.1 to 0.1.
It is preferably about 300 μm, and 0.5 to 100 μm.
It is more preferably about m, and even more preferably about 1 to 25 μm.

The electron transport layer 4 is formed in such a manner that the dye layer D is brought into contact with the dye layer by, for example, adsorbing, bonding (covalent bond, coordinate bond) a dye.

The dye layer D is a light-receiving layer that generates electrons and holes by receiving light, and is formed along the outer surface of the electron transport layer 4 and the inner surface of the hole 41 as shown in FIG. . Thereby, the electrons generated in the dye layer D can be efficiently transferred to the electron transport layer 4.

The pigment constituting the pigment layer D is not particularly limited, but examples thereof include pigments and dyes,
These can be used alone or in combination,
It is preferable to use a pigment from the viewpoint of less deterioration and deterioration with time, and a dye from the viewpoint of more excellent adsorptivity to the electron transport layer 4 (bondability with the electron transport layer 4).

The pigment is not particularly limited, but examples thereof include phthalocyanine pigments such as phthalocyanine green and phthalocyanine blue, fast yellow,
Azo series such as disazo yellow, condensed azo yellow, benzimidazolone yellow, dinitroaniline orange, benzimidazolone orange, toluidine red, permanent carmine, permanent red, naphthol red, condensed azo red, benzimidazolone carmine, benzimidazolone brown Pigments, anthrapyrimidine yellow, anthraquinone pigments such as anthraquinonyl red, azomethine pigments such as copper azomethine yellow,
Quinophthalone pigments such as quinophthalone yellow, isoindoline pigments such as isoindoline yellow, nitroso pigments such as nickel dioxime yellow, perinone pigments such as perinone orange, quinacridone magenta, quinacridone maroon, quinacridone scarlet, quinacridone red, etc. Quinacridone pigments, perylene red, perylene pigments such as perylene maroon, pyrrolopyrrole pigments such as diketopyrrolopyrrole red, organic pigments such as dioxazine pigments such as dioxazine violet, carbon black, lamp black, furnace black, Carbon pigments such as ivory black, graphite and fullerene, chromate pigments such as yellow lead, molybdate orange, cadmium yellow, cadmium lithopone yellow and cadmium Sulfide, cadmium lithopone orange, silver vermillion, cadmium red, cadmium lithopone red, sulfide pigments such as sulfur, ocher, titanium yellow, titanium barium nickel yellow, red iron oxide, amber, amber iron oxide, zinc iron chrome brown , Chrome oxide, cobalt green, cobalt chrome green, titanium cobalt green, cobalt blue, cerulean blue, cobalt aluminum chrome blue, iron black, manganese ferrite black, cobalt ferrite black, copper chrome black, copper chrome manganese black, etc. Pigments, hydroxide pigments such as Viridian,
Examples include ferrocyanide pigments such as dark blue, silicate pigments such as ultramarine blue, phosphate pigments such as cobalt violet and mineral violet, and inorganic pigments such as cadmium sulfide and cadmium selenide. The
These can be used alone or in combination of two or more.

The dye is not particularly limited, and examples thereof include RuL ₂ (SCN) ₂ , RuL ₂ Cl ₂ , RuL ₂ (CN) ₂ and Ruteni.
um535-bisTBA (manufactured by Solaronics), [RuL ₂ (NCS) ₂ ] ₂ H ₂ O-like metal complex dye, cyan dye, xanthene dye, azo dye, hibiscus dye, blackberry dye, raspberry dye, Pomegranate juice pigments, chlorophyll pigments and the like can be mentioned, and one or more of them can be used in combination. In addition, L in the said compositional | empirical formula shows 2,2'-bipyridine or its derivative (s).

On the upper surface of the electron transport layer 4 on which the dye layer D is formed, a layered (plate-shaped) hole transport layer 5 is provided. In other words, the hole transport layer 5 is provided so as to face the first electrode 3 with the electron transport layer 4 having the dye layer D formed therebetween. The hole transport layer 5 has a function of capturing and transporting holes generated in the dye layer D. In other words, the hole transport layer 5 has a function of transporting holes to the external circuit 100 via the second electrode 6 described later, or the hole transport layer itself serves as an electrode.

The average thickness of the hole transport layer 5 is not particularly limited, but is preferably about 1 to 500 μm, more preferably about 10 to 300 μm, and about 10 to 30 μm. Is more preferable.

The constituent material of the hole transport layer 5 is, for example, a substance having various ion-conducting properties, triphenyldiamine (monomer, polymer, etc.), polyaniline, polypyrrole, polythiophene, a phthalocyanine compound (eg, copper phthalocyanine), or these. Examples thereof include various p-type semiconductor materials such as derivatives of Al, nickel, cobalt, platinum, silver, gold, copper, molybdenum, titanium, tantalum, and alloys containing these. One kind or a combination of two or more kinds can be used, and in particular, a substance having ionic conductivity is preferably used. That is, the hole transport layer 5 is preferably composed mainly of a substance having ionic conductivity. Thereby, the hole transport layer 5 is
The holes generated in the dye layer D can be more efficiently transmitted.

Examples of the substance having this ion-conducting property include metal iodide compounds such as CuI and AgI, metal halide compounds such as metal bromide compounds such as AgBr, and metal thiocyanide such as CuSCN. Examples thereof include compounds and the like, and one or more of these may be used in combination. Among them, one or more of metal iodide compounds such as CuI and AgI are particularly preferable. More preferably, they are used in combination. Such a metal iodide compound is particularly excellent in ionic conduction characteristics. Therefore, the photoelectric conversion efficiency (energy conversion efficiency) of the solar cell 1 can be further improved by using the metal iodide compound.

Further, as shown in FIG. 2, the hole transport layer 5 is formed so as to enter the holes 41 of the electron transport layer 4 in which the dye layer D is formed. Thereby, the contact area between the dye layer D and the hole transport layer 5 can be increased, so that the hole transport layer 5 can more efficiently transfer the holes generated in the dye layer D. Therefore, the solar cell 1 can further improve the power generation efficiency. A layered (plate-shaped) second electrode 6 is provided on the upper surface of the hole transport layer 5.

The average thickness of the second electrode 6 is
It is appropriately set depending on the application and the like and is not particularly limited.

As the constituent material of the second electrode 6,
For example, aluminum, nickel, cobalt, platinum,
Examples thereof include metals such as silver, gold, copper, molybdenum, titanium, tantalum, alloys containing these, carbon, and the like, and one or more of these may be used in combination. The second electrode 6 can be omitted if necessary.

In such a solar cell 1, as shown in FIG. 5, when light is incident, electrons are excited mainly in the dye layer D to generate electrons (e ⁻ ) and holes (h ⁺ ). To do.
Among these, the electrons move to the electron transport layer 4 and the holes move to the hole transport layer 5, and between the first electrode 3 and the second electrode 6,
A potential difference (photoelectromotive force) is generated, and a current (photoexcitation current) flows in the external circuit 100.

The value of Vaccum Energy shown in FIG. 5 is
This is an example in which the electron transport layer 4 and the barrier layer 8 are made of titanium dioxide, and the hole transport layer 5 is made of CuI.

When this state is represented by an equivalent circuit, a current circulating circuit having a diode 200 as shown in FIG. 6 is formed.

Now, the barrier layer 8 will be described. The barrier layer 8 has a function of preventing or suppressing a short circuit (leakage) between the first electrode 3 and the hole transport layer 5. The barrier layer 8 is located between the first electrode 3 and the electron transport layer 4, and is formed so that its porosity is smaller than that of the electron transport layer 4.

When manufacturing the solar cell 1, as will be described later, for example, a hole transport layer material is applied to the upper surface of the electron transport layer 4 on which the dye layer D is formed, by a coating method. .

In this case, in a solar cell in which the barrier layer 8 is not provided, if the porosity of the electron transport layer 4 is increased, the hole transport layer material becomes the hole of the electron transport layer 4 in which the dye layer D is formed. It may penetrate into the inside 41 and reach the first electrode 3. That is, in the solar cell having no barrier layer 8, the leakage current increases due to the contact (short circuit) between the first electrode 3 and the hole transport layer 5, and the power generation efficiency (photoelectric conversion efficiency) is increased. May be reduced.

On the other hand, in the solar cell 1 provided with the barrier layer 8, the inconvenience as described above is prevented, and the decrease in power generation efficiency is suitably prevented or suppressed.

When the porosity of the barrier layer 8 is A [%] and the porosity of the electron transport layer 4 is B [%], B /
A is, for example, preferably about 1.1 or more, 5
It is more preferably about 10 or more, and even more preferably about 10 or more. Thereby, the barrier layer 8 and the electron transport layer 4 can exhibit their respective functions more suitably.

More specifically, the porosity A of the barrier layer 8 is preferably about 20% or less,
It is more preferably about 5% or less, further preferably about 2% or less. That is, the barrier layer 8 is preferably a dense layer. Thereby, the effect can be further improved.

Further, the thickness ratio of the barrier layer 8 and the electron transport layer 4 is not particularly limited, but is, for example, 1:99 to.
It is preferably about 60:40 and 10:90 to 4
It is more preferably about 0:60. In other words, the ratio of the barrier layer 8 to the whole of the barrier layer 8 and the electron transport layer 4 is preferably about 1 to 60% in thickness, and more preferably about 10 to 40%. Accordingly, the barrier layer 8 can more reliably prevent or suppress a short circuit due to contact between the first electrode 3 and the hole transport layer 5, and at the same time, the light arrival rate to the dye layer D is reduced. This can be suitably prevented.

More specifically, the average thickness (film thickness) of the barrier layer 8 is, for example, preferably about 0.01 to 10 μm, more preferably about 0.1 to 5 μm. More preferably, it is about 0.5 to 2 μm. Thereby, the effect can be further improved.

The constituent material of the barrier layer 8 is not particularly limited. For example, in addition to titanium oxide which is the main constituent material of the electron transport layer 4, for example, SrTiO ₃ , Zn.
Various metal oxides such as O, SiO ₂ , Al ₂ O ₃ and SnO ₂ , CdS, CdSe, TiC, Si ₃ N ₄ and Si
One kind or a combination of two or more kinds of various metal compounds such as C, B ₄ N, and BN can be used, and among them, one having an electric conductivity equivalent to that of the electron transport layer 4 is used. It is more preferable to use titanium oxide as a main component, particularly titanium oxide. By forming the barrier layer 8 with such a material, the electrons generated in the dye layer D can be more efficiently transferred from the electron transport layer 4 to the barrier layer 8, and as a result, the power generation efficiency of the solar cell 1 can be increased. Can be further improved.

The total resistance value in the thickness direction of the barrier layer 8 and the electron transport layer 4 is not particularly limited, but is preferably about 100 Ω / cm ² or more,
More preferably, it is about 1 kΩ / cm ² or more. This makes it possible to more reliably prevent or suppress a leak (short circuit) between the first electrode 3 and the hole transport layer 5.
There is an advantage that the reduction of the power generation efficiency of the solar cell 1 can be prevented.

The interface between the barrier layer 8 and the electron transport layer 4 may or may not be clear, but it is preferably not clear (unclear). That is, the barrier layer 8 and the electron transport layer 4 are preferably formed integrally. This makes it possible to transfer electrons more reliably (efficiently) between the barrier layer 8 and the electron transport layer 4.

Further, the barrier layer 8 and the electron transport layer 4 are
A structure in which materials having the same composition (for example, a material mainly containing titanium dioxide) is used, and only the porosities thereof are different, that is, a part of the electron transport layer 4 is part of the barrier layer 8 is formed.
May be configured to function as.

In this case, the electron transport layer 4 has a dense portion and a rough portion in the thickness direction, of which the dense portion functions as the barrier layer 8.

In this case, it is preferable that the dense portion is formed on the electron transport layer 4 on the first electrode 3 side.
It can also be formed at any position in the thickness direction.

In this case, the electron transport layer 4 has a structure having a portion sandwiching a rough portion between dense portions, a structure having a portion sandwiching a dense portion between rough portions, and the like. It may be.

The present invention is characterized by the surface texture of the upper surface of the first electrode 3. Hereinafter, this point (feature) will be described in detail.

The upper surface of the first electrode 3 is subjected to a smoothing treatment (details of which will be described later) to reduce irregularities on the surface. Thereby, the surface roughness of the upper surface of the first electrode 3 is adjusted, that is, the unevenness is reduced. Therefore, when the barrier layer 8 is formed, it is possible to prevent or suppress the protrusion of the upper surface of the first electrode 3 from protruding through the barrier layer 8.

Therefore, in the solar cell 1, a short circuit (leakage) due to contact between the first electrode 3 and the hole transport layer 5 or the like can be prevented or suppressed, and as a result, extremely excellent power generation efficiency can be obtained. (Photoelectric conversion efficiency) is obtained.

By this smoothing treatment, the upper surface of the first electrode 3 has a surface roughness R _max (JIS B 06
01 maximum height) is preferably 0.05-1 μ
m, more preferably 0.1 to 0.5 μm.

As a result, it is possible to more reliably prevent or suppress the protrusion of the upper surface of the first electrode 3 from protruding from the barrier layer 8.

The surface roughness R _max is H ≧ 1.1 R _max when the average thickness of the barrier layer 8 is H [μm].
It is preferable that the following relation is satisfied, and H ≧ 1.8R _max
It is more preferable to satisfy the following relationship. As a result, the above effect becomes more remarkable.

When the first electrode 3 is formed, the surface roughness R _max of the upper surface depends on the forming method, forming conditions, and the like.
However, in some cases, the smoothing process can be omitted in this case.

In such a solar cell 1, the incident angle of light to the dye layer D (electron transport layer 4 on which the dye layer D is formed) is 9
The photoelectric conversion efficiency at 0 ° is R _90, and the incident angle of light is 52 °
When the photoelectric conversion efficiency at R is R ₅₂ , R ₅₂ / R ₉₀ is 0.
It is preferable that it has a characteristic that it is about 8 or more, and more preferably about 0.85 or more. Satisfying such a condition means that the electron transport layer 4 on which the dye layer D is formed has a low directivity to light, that is, isotropic. Therefore, such a solar cell 1 is provided over almost the entire sunshine duration of the sun.
Power can be generated more efficiently.

Further, in the solar cell 1, when the voltage of 0.5 V is applied so that the first electrode 3 is positive and the second electrode 6 (hole transport layer 5) is negative, the resistance thereof is For example, the value is preferably 100 Ω / cm ² or more, more preferably 1 kΩ / cm ² or more. Having such characteristics means that in the solar cell 1, a short circuit (leakage) due to contact or the like between the first electrode 3 and the hole transport layer 5 is preferably prevented or suppressed. It is a thing. Therefore, in such a solar cell 1, the power generation efficiency (photoelectric conversion efficiency) can be further improved.

Such a solar cell 1 can be manufactured, for example, as follows. First, the substrate 2 made of soda glass or the like is prepared. As the substrate 2, a substrate having a uniform thickness and no bending is preferably used.

<1> First, the first electrode 3 is formed on the upper surface of the substrate 2. The first electrode 3 can be formed by using, for example, the material of the first electrode 3 composed of FTO or the like by using, for example, a vapor deposition method, a sputtering method, a printing method or the like.

In this state, relatively large irregularities are scattered on the upper surface of the first electrode 3, that is, the surface on the electron transport layer 4 (barrier layer 8) side.

<2> Next, the upper surface of the first electrode 3 is smoothed. The smoothing treatment is not particularly limited, and examples thereof include polishing treatment, etching treatment, and ashing treatment. Among them, it is particularly preferable to use polishing treatment and etching treatment. Further, these polishing treatments and etching treatments may be used alone or in combination.

According to such a treatment, the irregularities on the upper surface (surface) of the first electrode 3 can be reduced more reliably and in a short time, and the surface roughness can be adjusted appropriately. .

The polishing process and the etching process will be described in detail below. In the polishing process, for example, a polishing liquid containing a polishing agent (suspension in which the polishing agent is suspended in a liquid) is applied to the upper surface of the first electrode 3, and then a polishing cloth (a partner) is placed on the upper surface. Then, polishing can be carried out by relatively horizontally moving (for example, rotating) these.

When polishing is performed by rotation, the number of rotations is, for example, preferably about 100 to 5000 rpm, more preferably about 500 to 2500 rpm.

The abrasive is not particularly limited, but for example, particles (fine particles) of alumina (Al ₂ O ₃ ), silica (SiO ₂ ), diamond, total rare earth (TRO), cerium oxide (CeO ₂ ), etc. may be used. Among these, one kind or a combination of two or more kinds can be used.

The average particle size of the abrasive is preferably, for example, about 0.1 to 10 μm, and is 0.5.
More preferably, it is about 5 μm.

The polishing treatment can be carried out not only by using such a polishing liquid, but also by electrolytic polishing or the like.

On the other hand, the etching treatment is not particularly limited, and examples thereof include wet etching treatment, plasma etching, sputter etching, and dry etching treatment such as reactive ion etching. Of these, wet etching is particularly preferable. Etching process,
It is preferable to use a plasma etching process or a sputter etching process. By these etching treatments, the unevenness on the upper surface (surface) of the first electrode 3 can be reduced more reliably and in a short time.

Hereinafter, each etching process will be described in sequence. [Wet Etching Treatment] The wet etching treatment can be performed, for example, by bringing the etching liquid into contact with the first electrode 3 (for example, immersing the first electrode 3 in the etching liquid).

The composition of this etching solution is not particularly limited, but for example, nitric acid, sulfuric acid, phosphoric acid, (orthophosphoric acid, metaphosphoric acid, pyrophosphoric acid, triphosphoric acid, tetraphosphoric acid, diphosphoric pentoxide, etc.), Acidic substances such as hydrogen fluoride, acetic acid, hydrogen chloride, boric acid, oxalic acid and tetrafluoroboric acid, alkaline substances such as sodium hydroxide, potassium hydroxide, magnesium hydroxide, calcium hydroxide, chromium oxide (IV), Hydrogen peroxide, iron (III) chloride, perchloric acid, ammonium persulfate, oxidizing agents such as copper nitrate, iron (III) chloride,
Liquid selected from one or a mixture of two or more selected from salts such as ammonium persulfate, copper nitrate, potassium carbonate, sodium phosphate, sodium carbonate, sodium nitrate, ammonium chloride, and at least one selected from these And a liquid containing at least one liquid selected from methanol, ethanol, butanol, water, nitric acid, sulfuric acid, acetic acid, and the like.

The temperature of the etching solution varies depending on the composition of the etching solution, the etching method, etc., but is, for example, 5 to 1
The temperature is preferably about 50 ° C, more preferably about 15 to 80 ° C.

Further, the contact time between the first electrode 3 and the etching solution is, for example, preferably about 0.1 to 20 minutes, more preferably about 0.5 to 5 minutes.

[Plasma Etching Treatment] The plasma etching treatment can be performed, for example, as follows.

By fixing the laminated body of the first electrode 3 and the substrate 2 in the etching apparatus and introducing the reaction gas into the apparatus under reduced pressure or vacuum while applying the reaction gas and high frequency power. , Generate plasma. Then, with this plasma, the convex portion on the upper surface of the first electrode 3 is scraped off,
Reduce irregularities.

Suitable reaction gases include, for example, methane gas (CH ₄ ), hydrogen iodide gas (HI),
The gas flow rate is, for example, preferably about 10 to 6000 sccm, more preferably about 50 to 2000 sccm.

The pressure in the device is, for example, 10 ⁻⁶ to 10
It is preferably about Torr, and 10 ^{-3 to 1} Torr
More preferably, it is about r.

High frequency power is, for example, 1 MHz to 5 GH.
It is preferably about z, and more preferably 10 MHz to 5 GHz.

The plasma irradiation time (high-frequency power application time) is preferably about 0.5 to 120 seconds, more preferably about 5 to 60 seconds.

[Sputter Etching Treatment] The sputter etching treatment can be performed, for example, as follows.

A laminated body of the first electrode 3 and the substrate 2 is fixed in an etching apparatus, and plasma is generated by applying an argon gas (inert gas) filled in the apparatus and high frequency power. . Then, with this plasma, the convex portions on the upper surface of the first electrode 3 are scraped off, and the irregularities are reduced.

The pressure in the apparatus is, for example, 10 ⁻⁶ to 10
Torr is preferably about 10 ^{−3 to 1} Torr
More preferably, it is about r.

High frequency power is, for example, 1 MHz to 5 GH.
It is preferably about z, and more preferably about 10 MHz to 5 GHz.

The plasma irradiation time (high output power application time) is, for example, preferably about 0.5 to 120 seconds, more preferably about 5 to 60 seconds.

<3> Next, the barrier layer 8 is applied to the first electrode 3
Formed on the upper surface of. The barrier layer 8 can be formed by, for example, a sol-gel method, a vapor deposition (vacuum vapor deposition) method, a sputtering method (high-frequency sputtering, DC sputtering), a spray pyrolysis method, a jet mold (plasma spraying) method, a CVD method, or the like. Of these, it is preferable to form them by the sol-gel method.

This sol-gel method is extremely easy to operate. For example, by using it in combination with various coating methods such as dipping, dropping, doctor blade, spin coating, brush coating, spray coating and roll coater, The barrier layer 8 can be preferably formed in a film shape (thick film and thin film) without requiring a large-scale device.

Further, according to the coating method, the barrier layer 8 having a desired pattern shape can be easily obtained by using, for example, masking.

This sol-gel method does not allow (prevent) a reaction (for example, hydrolysis, polycondensation, etc.) of a titanium compound (organic or inorganic) described later in the barrier layer material (hereinafter referred to as " MOD (Metal Organic depositio
n) Law ”. ), Or a method which allows this, but it is particularly preferable to use the MOD method.

According to this MOD method, the stability of the titanium compound (organic or inorganic) in the barrier layer material is maintained, and the barrier layer 8 is more easily and surely (reproducibly) and dense. (Porosity within the above range).

In particular, titanium tetraisopropoxide (T
PT), titanium tetra methoxide, titanium tetraethoxide, chemically very unstable (easily decomposed, such as titanium tetrabutoxide) using an organic titanium compound such as titanium alkoxide, dense TiO ₂ layer (the This MOD method is optimal when forming the inventive barrier layer 8). Hereinafter, a method of forming the barrier layer 8 by the MOD method will be described.

[Preparation of Barrier Layer Material] For example, one of organic titanium compounds such as titanium tetraisopropoxide (TPT), titanium tetramethoxide, titanium tetraethoxide and titanium alkoxide such as titanium tetrabutoxide, or In the case of using a combination of two or more kinds, first, this organic titanium compound (or this solution) is mixed with, for example, absolute ethanol, 2-butanol, or 2
Dissolve in an organic solvent (or a mixed solvent thereof) such as propanol or 2-n-butoxyethanol.

Thus, the concentration (content) of the organic titanium compound in the solution is adjusted (for example, 0.1 to 10 mol).
/ L) to adjust the viscosity of the resulting barrier layer material. The viscosity of the barrier layer material is appropriately set depending on the type of the coating method and the like, and is not particularly limited, but when spin coating is used, it is preferably a high viscosity (for example, about 0.5 to 20 cP), When using a spray coat, preferably a low viscosity (eg 0.1-2 cP
Degree).

Next, a compound capable of stabilizing the titanium alkoxide such as titanium tetrachloride, acetic acid, acetylacetone, triethanolamine, diethanolamine, etc. is added to this solution as an additive.

By adding these additives, the alkoxide (alkoxyl group) in the titanium alkoxide that coordinates with titanium is substituted, and these additives are coordinated with the titanium atom. In this case, the compounding ratio of the additive and the titanium alkoxide is not particularly limited, but for example, the molar ratio is preferably about 1: 2 to 8: 1.

More specifically, when diethanolamine is coordinated to the titanium alkoxide, it replaces (substitutes) the alkoxide (alkoxyl group) of the titanium alkoxide, and two molecules of diethanolamine are coordinated to the titanium atom. It is a more stable compound in forming titanium dioxide. The same applies to combinations in other cases.

As a result, a barrier layer material (sol solution for forming barrier layer: sol solution for MOD) is obtained.

When an inorganic titanium compound such as titanium tetrachloride (TTC) is used, the inorganic titanium compound (or a solution thereof) is used as anhydrous ethanol, 2-butanol, 2-propanol, 2-n-butoxyethanol. When dissolved in an organic solvent such as (or a mixed solvent thereof), the organic solvent coordinates with titanium and becomes a stable compound without adding an additive.

Further, when an organic titanium compound such as titanium oxyacetylacetonate (TOA) is used,
Since this organic titanium compound (or this solution) is stable alone, a stable barrier layer material can be obtained by dissolving it in the organic solvent.

In the present invention, when the barrier layer 8 is formed by the MOD method, among the above-mentioned three solutions,
An organic titanium compound (or a solution thereof) such as titanium alkoxide such as titanium tetraisopropoxide (TPT), titanium tetramethoxide, titanium tetraethoxide and titanium tetrabutoxide is dissolved (or diluted) in a solvent.
Then, by adding additives such as titanium tetrachloride, acetic acid, acetylacetone, triethanolamine, and diethanolamine to this solution, these additives are coordinated with the titanium atom to stabilize the formation of titanium dioxide. The method of obtaining the compound is optimal.

As a result, the chemically unstable titanium alkoxide can be made into a stable compound.
It is possible to form the dense barrier layer 8 of the present invention by using a highly stabilized compound as a material for forming the dense barrier layer 8 of titanium dioxide in the present invention.

[Formation of Barrier Layer 8] A barrier layer material is applied to the upper surface of the first electrode 3 by a coating method (for example, spin coating) to form a film. When spin coating is used as the coating method, the rotation speed is 500 to 4000 rpm.
It is preferably carried out to the extent.

Then, heat treatment is applied to the coating film. Thereby, the organic solvent is volatilized and removed. The heat treatment condition is preferably about 50 to 250 ° C.
It is about 60 minutes, more preferably about 100 to 200 ° C. and about 5 to 30 minutes.

Such heat treatment can be carried out, for example, in air or nitrogen gas, or in addition to various inert gases,
Vacuum or reduced pressure (for example, 10 ⁻¹ to 10 ⁻⁶ Tor)
It may be performed in a non-oxidizing atmosphere such as r).

The coating of the barrier layer material on the upper surface of the first electrode 3 may be performed while heating the first electrode 3.

Further, the coating film is heat-treated at a higher temperature than the above heat treatment. As a result, the organic components remaining in the coating film are removed and titanium dioxide (TiO ₂ ) is sintered to form the barrier layer 8 made of titanium dioxide having an amorphous or anatase type crystal structure. The heat treatment conditions are preferably about 300 to 700 ° C. for about 1 to 70 minutes, more preferably about 400 to 550 ° C. for about 5 to 45 minutes.

The atmosphere of such heat treatment can be the same as that of the heat treatment.

The above operation is preferably carried out in the range of 1 to 20.
The barrier layer 8 having an average thickness as described above is formed about once, more preferably about 1 to 10 times.

In this case, the thickness (film thickness) of the coating film obtained by one operation described above is preferably about 100 nm or less, and more preferably about 50 nm or less.
By forming the barrier layer 8 by laminating such thin films, the barrier layer 8 can be made more uniform and dense. Further, the adjustment of the film thickness obtained by the above-described operation can be easily performed by adjusting the viscosity of the barrier layer material.

Prior to the formation of the barrier layer 8, the first
The upper surface of the electrode 3 of, for example, O ₂ plasma treatment, EB
The organic substance attached to the upper surface of the first electrode 3 may be removed by performing a treatment, a cleaning treatment with an organic solvent (for example, ethanol, acetone, or the like). in this case,
A mask layer is formed on the upper surface of the first electrode 3 and masked in advance, leaving a portion for forming the barrier layer 8. The mask layer may be removed after the barrier layer 8 is formed, or after the solar cell 1 is completed.

<4> Next, the electron transport layer 4 is formed on the upper surface of the barrier layer 8. The electron transport layer 4 is, for example, sol
It can be formed by a gel method, a vapor deposition method, a sputtering method or the like, and among them, the sol-gel method is preferable.

This sol-gel method is extremely easy to operate. For example, by using it in combination with various coating methods such as dipping, dropping, doctor blade, spin coating, brush coating, spray coating, and roll coater, The electron transport layer 4 is preferably used without requiring a large-scale device.
Can be formed into a film (thick film and thin film).

Further, according to the coating method, the electron transport layer 4 having a desired pattern can be easily obtained by using, for example, masking.

For forming the electron transport layer 4, it is preferable to use a sol liquid containing a powder of the electron transport layer material. Thereby, the electron transport layer 4 can be made porous more easily and reliably.

The average particle size of the powder of the electron transport layer material is not particularly limited, but is preferably about 1 nm to 1 μm, more preferably about 5 to 50 nm. By setting the average particle size of the powder of the electron transport layer material within the above range, it is possible to improve the uniformity of the powder of the electron transport layer material in the sol liquid. Further, since the surface area (specific surface area) of the obtained electron transport layer 4 can be increased by reducing the average particle size of the powder of the electron transport layer material in this way, the formation region (formation of the dye layer D) Area) can be made larger, and solar cell 1
Contribute to the improvement of power generation efficiency. Hereinafter, an example of a method of forming the electron transport layer 4 will be described.

[Preparation of Titanium Oxide Powder (Powder for Electron Transport Layer Material)] <4-A0> Rutile type titanium dioxide powder and anatase type titanium dioxide powder are mixed at a predetermined mixing ratio (only anatase type titanium dioxide powder is used). , And rutile type titanium dioxide powder alone).

The average particle size of these rutile type titanium dioxide powders and the average particle size of the anatase type titanium dioxide powder may be different or the same, but they are different. Is preferred. The average particle size of the titanium oxide powder as a whole is within the above range.

[Preparation of Sol Solution (Electron Transport Layer Material)] <4-A1> First, for example, titanium such as titanium tetraisopropoxide (TPT), titanium tetramethoxide, titanium tetraethoxide and titanium tetrabutoxide. Organic titanium compounds such as alkoxide and titanium oxyacetylacetonate (TOA), and titanium tetrachloride (T
TC) and the like, one or a combination of two or more of inorganic titanium compounds, for example, anhydrous ethanol, 2-
It is dissolved in an organic solvent (or a mixed solvent thereof) such as butanol, 2-propanol and 2-n-butoxyethanol.

At this time, the concentration (content) of the titanium compound (organic or inorganic) in the solution is not particularly limited, but is preferably about 0.1 to 3 mol / L, for example.

Next, if necessary, various additives are added to this solution. For example, when titanium alkoxide is used as the organic titanium compound, the stability is low,
For example, acetic acid, acetylacetone, nitric acid, etc. are added. In this case, the compounding ratio of the additive and the titanium alkoxide is not particularly limited, but for example, the molar ratio is preferably about 1: 2 to 8: 1.

<4-A2> Next, water such as distilled water, ultrapure water, ion-exchanged water, or RO water is mixed with this solution. The mixing ratio of this water and the organic titanium compound is preferably about 1: 4 to 4: 1 in terms of molar ratio.

<4-A3> Next, the titanium oxide powder prepared in the step <4-A0> is mixed with the solution to obtain a suspension (dispersion) liquid.

<4-A4> Further, this suspension is diluted with the above-mentioned organic solvent (or mixed solvent). This prepares a sol liquid. The dilution ratio is preferably about 1.2 to 3.5 times, for example.

The content of titanium oxide powder (electron transport layer material powder) in the sol liquid is not particularly limited, but is preferably about 0.1 to 10 wt% (weight%), More preferably, it is about 0.5 to 5 wt%. Thereby, the porosity of the electron transport layer 4 can be preferably set within the above range.

[Formation of Electron Transport Layer (Titanium Oxide Layer) 4] <4-A5> While the barrier layer 8 is preferably heated, a coating method (for example, dropping) is applied on the upper surface of the barrier layer 8.
The sol solution is applied to obtain a film-like body (coating film). The heating temperature is not particularly limited, but is, for example, 80 to 180.
The temperature is preferably about 0 ° C, more preferably about 100 to 160 ° C.

The above operation is preferably carried out in the range of 1 to 10
The electron transport layer 4 having the above-mentioned average thickness is formed about once, more preferably about 5 to 7 times.

Next, the electron transport layer 4 may be subjected to heat treatment (for example, firing) at a temperature of about 250 to 500 ° C. for about 0.5 to 3 hours, if necessary.

<4-A6> The electron transport layer 4 obtained in the step <4-A5> can be subjected to a post-treatment, if necessary.

As the post-processing, for example, mechanical processing (post-processing) such as grinding and polishing for adjusting the shape.
Other examples include post-treatment such as cleaning and chemical treatment. The electron transport layer 4 is obtained through the above steps.

<5> Next, the electron transport layer 4 and a liquid containing the dye as described above (for example, a solution of the dye dissolved in a solvent, a suspension of the dye suspended in the solvent) are immersed, for example. , Dyes D are formed on the outer surface of the electron transport layer 4 and the inner surfaces of the holes 41 by, for example, adsorbing, bonding, and the like.

More specifically, the substrate 2, the first electrode 3,
The dye layer D can be easily formed along the outer surface of the electron transport layer 4 and the inner surface of the hole 41 by immersing the laminate of the barrier layer 8 and the electron transport layer 4 in the liquid containing the dye.

The solvent (liquid) that dissolves or suspends (disperses) the dye is not particularly limited, and examples thereof include various types of water, methanol, ethanol, isopropyl alcohol, acetonitrile, ethyl acetate, ether, methylene chloride, NMP (N). -Methyl-2-pyrrolidone) and the like, and one or more of them can be used in combination.

After that, the laminate is treated with the solution (suspension).
From the inside, the solvent is removed by, for example, a method of natural drying or a method of blowing a gas such as air or nitrogen gas.

Further, if necessary, this laminate may be dried in a clean oven or the like at a temperature of about 60 to 100 ° C. for about 0.5 to 2 hours. Thereby, the dye can be more strongly adsorbed (bonded) to the electron transport layer 4.

<6> Next, the hole transport layer 5 is formed on the upper surface of the dye layer D (the electron transport layer 4 on which the dye layer D is formed).

For the hole transport layer 5, for example, a hole transport layer material (electrode material) containing a substance having ionic conductivity such as CuI is provided on the upper surface of the electron transport layer 4 on which the dye layer D is formed.
For example, it is preferably formed by coating by various coating methods such as dipping, dropping, doctor blade, spin coating, brush coating, spray coating and roll coater.

According to such a coating method, the hole transport layer 5
Can be more surely permeated into the holes 41 of the electron transport layer 4 in which the dye layer D is formed.

Further, after the coating film is formed, the coating film may be heat-treated, but the dye layer D of the hole transport layer material may be used.
Coating on the upper surface of the electron transport layer 4 on which the
It is preferable to perform it while heating (the electron transport layer 4 on which the dye layer D is formed). As a result, the hole transport layer 5 can be more quickly formed.
Is advantageous in shortening the manufacturing time of the solar cell 1.

The heating temperature is preferably 5
It is set to about 0 to 150 ° C. When the heat treatment is performed after forming the coating film, the coating film may be dried before the heat treatment. Further, the above operation may be repeated a plurality of times.

More specifically, the substrate 2, the first electrode 3, the barrier layer 8 are placed on a hot plate heated to about 80 ° C.
And the laminated body of the electron transport layer 4 on which the dye layer D is formed is installed, and the hole transport layer material is dropped on the upper surface of the electron transport layer 4 on which the dye layer D is formed, and dried. By repeating this operation a plurality of times to stack the layers, the hole transport layer 5 having the above-described average thickness is formed.

The solvent used for the hole transport layer material is not particularly limited, but, for example, an organic solvent such as acetonitrile, ethanol, methanol, isopropyl alcohol, etc., or one kind or a combination of two or more kinds such as various kinds of water is used. be able to.

Acetonitrile is preferably used as a solvent for dissolving a substance having ionic conductivity. In addition, as a substance having ionic conduction characteristics, CuI
In the case of using, a cyanoethyl compound such as cyanoresin may be added as a CuI binder in the CuI acetonitrile solution. In this case, Cu
I and the cyanoethylated compound are preferably mixed (blended) at a mass ratio (weight ratio) of, for example, about 95.5: 0.5 to 95: 5.

The hole transport layer material preferably contains a substance for improving the hole transport efficiency.
When the hole transport layer material contains this substance, in the hole transport layer 5, the carrier mobility becomes higher due to the improved ionic conductivity, so that the electric conductivity is further improved.

The substance is not particularly limited, but examples thereof include halides such as ammonium halides, and it is particularly preferable to use ammonium halides such as tetrapropylammonium iodide (TPAI). By using tetrapropylammonium iodide, the carrier mobility of a substance having ionic conduction characteristics is further improved, and the electric conductivity of the hole transport layer 5 is further improved.

By adding the above-mentioned substance such as TPAI to the hole transport layer material, it is possible to suppress an increase in the crystal size when the substance having the ion conductive property is crystallized, The following effects can also be obtained.

That is, depending on, for example, the type of substance having ionic conductivity and the above-mentioned heating temperature, when the substance having ionic conductivity is crystallized, its crystal size becomes too large (the volume expansion of the crystal Go too far),
In particular, when such crystallization occurs in the holes (fine holes) of the barrier layer 8, cracks are generated in the barrier layer 8 and, as a result, a partial portion between the hole transport layer 5 and the first electrode 3 is generated. Short circuit (contact) may occur.

On the other hand, when the hole transport layer material contains this substance, the substance having ion-conducting properties suppresses the increase in crystal size and becomes relatively small in crystal size. Therefore, the inconveniences described above can be suitably suppressed.

The content of this substance in the hole transport layer material is not particularly limited, but is, for example, 10 ⁻⁴ to 1
It is preferably about 0 ^-1 wt% (weight%), and 10 ^-4
More preferably, it is about 10 ^-2 wt%. Within such a numerical range, the above-mentioned effect becomes more remarkable.

Further, the hole transport layer 5 is formed of p as described above.
In the case of using a p-type semiconductor material, the p-type semiconductor material may be, for example, acetone or isopropyl alcohol (IP
A) A hole transport layer material is prepared by dissolving (or suspending) it in various organic solvents (or mixed solvents containing these) such as ethanol. Using this hole transport layer material, the hole transport layer 5 is formed (formed) in the same manner as described above.

<7> Next, the second electrode 6 is formed on the upper surface of the hole transport layer 5. The second electrode 6 is formed by using, for example, a vapor deposition method using the material of the second electrode 6 made of platinum or the like.
It can be formed by using a sputtering method, a printing method, or the like. The solar cell 1 is manufactured through the above steps.

Although the photoelectric conversion element of the present invention has been described above based on the illustrated embodiments, the present invention is not limited to these. Each part constituting the photoelectric conversion element can be replaced with one having any configuration capable of exhibiting the same function.

The photoelectric conversion element of the present invention is applicable not only to solar cells but also to various elements (light receiving elements) such as optical sensors and optical switches that receive light and convert it into electric energy. Is something that can be done.

Further, in the photoelectric conversion element of the present invention, the incident direction of light may be from the opposite direction, unlike the one shown in the drawing. That is, the incident direction of light is arbitrary.

[0218]

EXAMPLES Next, specific examples of the present invention will be described.

Example 1 The solar cell (photoelectric conversion element) shown in FIG. 1 was manufactured as follows.

-0- First, the dimensions: length 30 mm x width 35
A soda glass substrate having a size of mm × thickness of 1.0 mm was prepared.
Next, this soda glass substrate was immersed in a cleaning liquid (mixed liquid of sulfuric acid and hydrogen peroxide solution) at 85 ° C. for cleaning to clean the surface.

-1- The FTO electrode (first electrode) having dimensions of 30 mm in length × 35 mm in width × 1 μm in thickness was formed on the upper surface of the soda glass substrate by vapor deposition.

-2-Next, FTO electrode (first electrode)
Was smoothed on the upper surface of the. This was done as follows.

A polishing solution prepared by suspending silica (SiO ₂ ) (abrasive) having an average particle diameter of 5 μm in water was applied to the upper surface of the FTO electrode (first electrode), and a polishing cloth rotating at 1000 rpm was pressed against it. Polished for 10 seconds. The surface roughness R _max of the upper surface of the FTO electrode was 0.3 μm.

-3- Next, a barrier layer was formed in a region of vertical 30 mm × horizontal 30 mm on the upper surface of the smoothed FTO electrode. This was done as follows.

[Preparation of Barrier Layer Material] First, titanium tetraisopropoxide (organic titanium compound) was added to 2-n-
It was dissolved in butoxyethanol to a concentration of 0.5 mol / L.

Then, diethanolamine (additive) was added to this solution. The mixing ratio of diethanolamine and titanium tetraisopropoxide was set to 2: 1 (molar ratio).

Thus, a barrier layer material was obtained. In addition,
The viscosity of the barrier layer material was 3 cP.

[Formation of Barrier Layer] The barrier layer material was applied by spin coating (coating method) to obtain a coating film. The spin coating was performed at a rotation speed of 1500 rpm.

Then, the laminated body of the soda glass substrate, the FTO electrode and the coating film was placed on a hot plate and
The coating film was dried by heat treatment at 60 ° C. for 10 minutes.

[0230] Further, the above laminated body was heated at 480 ° C for 30
The organic components remaining in the coating film were removed by applying a heat treatment in the oven for 1 minute. This operation was repeated 10 times so that the layers were laminated.

Thus, a barrier layer having a porosity of less than 1% was obtained. The average thickness of this barrier layer is 0.9 μm.
Met.

-4- Next, a titanium oxide layer (electron transport layer) was formed on the upper surface (entire surface) of the barrier layer. This was done as follows.

[Preparation of Titanium Oxide Powder] Titanium oxide powder made of a mixture of rutile type titanium dioxide powder and anatase type titanium dioxide powder was prepared. The average particle size of the titanium oxide powder was 40 nm, and the compounding ratio of the rutile type titanium dioxide powder and the anatase type titanium dioxide powder was 60:40 by weight.

[Preparation of Sol Solution (Titanium Oxide Layer Material)] First, titanium tetraisopropoxide was dissolved in 2-propanol to a concentration of 1 mol / L.

Next, acetic acid (additive) was added to this solution,
Mix with distilled water. The mixing ratio of acetic acid and titanium tetraisopropoxide is 1: 1 (molar ratio), and the mixing ratio of distilled water and titanium tetraisopropoxide is 1: 1 (molar ratio). So that

Next, the prepared titanium oxide powder was mixed with this solution. Further, this suspension was diluted 2-fold with 2-propanol. Thus, a sol liquid (titanium oxide layer material) was prepared. The content of titanium oxide powder in the sol solution was 3 wt%.

[Formation of Titanium Oxide] Soda glass substrate,
The laminate of the FTO electrode and the barrier layer was placed on a hot plate heated to 140 ° C., the sol liquid (titanium oxide layer material) was dropped (coating method) on the upper surface of the barrier layer, and dried. This operation was repeated 7 times so that the layers were laminated.

Thus, a titanium oxide layer having a porosity of 34% was obtained. The average thickness of this titanium oxide layer was 7.
It was 2 μm.

The resistance value in the thickness direction of the entire barrier layer and electron transport layer was 1 kΩ / cm ² or more.

-5-Next, soda glass substrate, FT
The laminated body of the O electrode, the barrier layer and the titanium oxide layer was immersed in a saturated ethanol solution of ruthenium trisbipidyl (organic dye), and then taken out from the ethanol solution.
Ethanol was volatilized by natural drying. Furthermore, 80
After drying in a clean oven at 0 ° C. for 0.5 hours, it was left overnight. As a result, a dye layer was formed along the outer surface of the titanium oxide layer and the inner surface of the holes.

-6- Next, soda glass substrate and FT
A laminate of the titanium oxide layer on which the O electrode, the barrier layer and the dye layer D were formed was placed on a hot plate heated to 80 ° C., and on the upper surface of the titanium oxide layer on which the dye layer D was formed,
A CuI acetonitrile solution (hole transport layer material) was added dropwise and dried. By repeating this operation to stack the layers, the dimensions: length 30 mm × width 30 mm × thickness 30 μm
CuI layer (hole transport layer) was formed.

Tetrapropylammonium iodide was added to the acetonitrile solution so as to be 10 ⁻³ wt%.

In addition, CuI was added to the acetonitrile solution.
As a binder of, cyanoresin (cyanoethylated product) was added. In addition, CuI and cyanoresin were mixed in a mass ratio (weight ratio) of 97: 3.

-7- Then, on the upper surface of the CuI layer, dimensions: 30 mm in length × 30 mm in width × 0.1 in thickness by vapor deposition.
mm platinum electrode (second electrode) was formed.

Example 2 A solar cell was manufactured in the same manner as in Example 1 except that wet etching treatment was carried out instead of polishing treatment.

The laminate of the FTO electrode and the soda glass substrate was immersed in an acidic aqueous solution (etching solution) in which hydrochloric acid, water and nitric acid were mixed at a ratio of 1: 1: 0.2 at 30 ° C. for 3 minutes. Then, the laminate was taken out from the aqueous acid solution. The surface roughness R _max of the upper surface of the FTO electrode is
It was 0.3 μm.

The porosity of the obtained barrier layer is 1%.
And the average thickness was 1.0 μm.

The titanium oxide layer (electron transport layer) thus obtained had a porosity of 35% and an average thickness of 7.2 μm.
It was m.

The resistance value in the thickness direction of the entire barrier layer and titanium oxide layer was 1 kΩ / cm ² or more.

Example 3 A solar cell was manufactured in the same manner as in Example 1 except that plasma etching treatment was carried out instead of polishing treatment.

The laminated body of the FTO electrode and the soda glass substrate was fixed in the etching equipment, and the pressure inside the equipment was adjusted to 10 ⁻³ T.
As orr, HI gas (reaction gas) was introduced at 1500 sccm, and high frequency power of 20 MHz was applied for 10 seconds. The surface roughness R of the upper surface of the FTO electrode
_max was 0.2 μm.

The porosity of the obtained barrier layer is 1%.
And the average thickness was 0.9 μm.

The titanium oxide layer (electron transport layer) thus obtained had a porosity of 36% and an average thickness of 7.0 μm.
It was m.

The resistance value in the thickness direction of the entire barrier layer and titanium oxide layer was 1 kΩ / cm ² or more.

Example 4 A solar cell was manufactured in the same manner as in Example 1 except that a sputter etching process was performed instead of the polishing process.

In the etching apparatus, the laminated body of the FTO electrode and the soda glass substrate was fixed and filled with argon gas,
A high frequency power of 20 MHz was applied for 20 seconds. In addition, F
The surface roughness R _max of the upper surface of the TO electrode was 0.4 μm.

The porosity of the obtained barrier layer is 1%.
And the average thickness was 0.8 μm.

The porosity of the obtained titanium oxide layer (electron transport layer) was 35%, and the average thickness was 7.2 μm.
It was m.

The resistance value in the thickness direction of the entire barrier layer and titanium oxide layer was 1 kΩ / cm ² or more.

Example 5 A solar cell was manufactured in the same manner as in Example 1 except that both polishing treatment and wet etching treatment were performed instead of the polishing treatment.

A polishing liquid prepared by suspending silica (SiO ₂ ) (abrasive) having an average particle diameter of 5 μm in water was applied on the upper surface of the FTO electrode (first electrode), and a polishing cloth rotating at 1000 rpm was pressed against it. Polished for 10 seconds.

Then, hydrochloric acid, water and nitric acid were added at 1: 1: 0.
F in an acidic aqueous solution (etching solution) mixed at a ratio of 2
The laminated body of the TO electrode and the soda glass substrate was immersed for 3 minutes. Then, the laminate was taken out from the aqueous acid solution. The surface roughness R _max of the upper surface of the FTO electrode is
It was 0.2 μm.

The porosity of the obtained barrier layer is 1%.
And the average thickness was 0.7 μm.

The titanium oxide layer (electron transport layer) thus obtained had a porosity of 36% and an average thickness of 7.1 μm.
It was m.

The resistance value in the thickness direction of the entire barrier layer and titanium oxide layer was 1 kΩ / cm ² or more.

(Comparative Example) A solar cell was manufactured in the same manner as in Example 1 except that the smoothing treatment was omitted. The surface R _max of the upper surface of the FTO electrode was 1.2 μm.

The porosity of the obtained barrier layer is 1%.
And the average thickness was 0.8 μm.

The titanium oxide layer (electron transport layer) thus obtained had a porosity of 36% and an average thickness of 7.3 μm.
It was m.

The resistance value in the thickness direction of the entire barrier layer and titanium oxide layer was 20 Ω / cm ² .

(Evaluation 1) In the solar cells manufactured in Examples 1 to 5 and Comparative Example, resistance values were obtained when a voltage of 0.5 V was applied so that the FTO electrode was positive and the platinum electrode was negative. Were measured respectively.

(Evaluation 2) The solar cells manufactured in Examples 1 to 5 and Comparative Example were each irradiated with light from an artificial solar lamp, and the photoelectric conversion efficiency at this time was measured. The incident angles of light to the dye layer (titanium oxide layer on which the dye layer is formed) are set to 90 ° and 52 °, and the light incident angle is 90
The photoelectric conversion efficiency at ₉₀ ° was R _90, and the photoelectric conversion efficiency at 52 ° was R ₅₂ . Evaluation 1 and Evaluation 2
The results are shown in Table 1.

[0272]

[Table 1]

From the results shown in Table 1, in the solar cells (Examples 1 to 5) in which the surface roughness R _max of the upper surface of the first electrode was adjusted by performing the smoothing treatment, the FTO electrode and Cu were used.
A short circuit due to contact with the I layer was suitably prevented or suppressed, and the photoelectric conversion efficiency was excellent.

On the other hand, the solar cells of Comparative Examples in which the smoothing treatment was omitted were all inferior in photoelectric conversion efficiency.

In the comparative example, the photoelectric conversion efficiency is inferior.
As is clear from the results of Evaluation 1, the FTO electrode and Cu
It is considered that this is caused by the generation of leakage current due to a short circuit (contact) with the I layer.

The solar cells of Examples 1 to 5 all have R ₅₂ / R ₉₀ of 0.85 or more, which means that the solar cells of Examples 1 to 5 have directivity to light. It was lower.

[0277]

As described above, according to the present invention, since the unevenness of the surface of the first electrode on the electron transport layer side is small, the unevenness of the surface of the first electrode is formed when the barrier layer is formed. The part can be prevented or suppressed from penetrating through the barrier layer. As a result, in the photoelectric conversion element, the generation of leakage current is preferably prevented or suppressed, and an excellent photoelectric conversion element can be obtained. Further, the photoelectric conversion element of the present invention is easy to manufacture and can be manufactured at low cost.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional view showing a case where a photoelectric conversion element of the present invention is applied to a solar cell.

FIG. 2 is an enlarged view showing a cross section of the solar cell in the vicinity of the central portion in the thickness direction.

FIG. 3 is a partially enlarged view showing a cross section of an electron transport layer on which a dye layer is formed.

FIG. 4 is a schematic diagram showing a configuration of an electron transport layer and a dye layer.

FIG. 5 is a schematic view showing the principle of a solar cell.

FIG. 6 is a diagram showing an equivalent circuit of the solar cell circuit shown in FIG.

[Explanation of symbols]

1 solar cell 2 substrates 3 First electrode 4 Electron transport layer 41 holes 5 Hole transport layer 6 Second electrode 8 barrier layers 100 external circuit 200 diodes D dye layer

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 5F051 AA14 CB13 FA03 FA06                 5H032 AA06 AS01 AS06 AS09 AS12                       AS16 AS19 BB05 EE02 EE03                       EE06 HH00 HH01 HH04 HH08

Claims (44)

[Claims] 1. A first electrode, a second electrode that is installed so as to face the first electrode, and is located between the first electrode and the second electrode, and at least one of them is provided. A photoelectric conversion element comprising: an electron transporting layer having a porous portion; a dye layer in contact with the electron transporting layer; and a hole transporting layer located between the electron transporting layer and the second electrode. A barrier layer that prevents or suppresses a short circuit between the first electrode and the hole transport layer, and the surface of the first electrode on the electron transport layer side has irregularities on the surface. A photoelectric conversion element, which has been subjected to a smoothing treatment to reduce it. 2. A first electrode, a second electrode provided to face the first electrode, and located between the first electrode and the second electrode, and at least one of them. A photoelectric conversion element comprising: an electron transporting layer having a porous portion; a dye layer in contact with the electron transporting layer; and a hole transporting layer located between the electron transporting layer and the second electrode. A barrier layer for preventing or suppressing a short circuit between the first electrode and the hole transport layer, and a surface roughness R of a surface of the first electrode on the electron transport layer side.
_A photoelectric conversion element having a _max of 0.05 to 1 μm. 3. The photoelectric conversion element according to claim 2, wherein the relationship of H ≧ 1.1R _max is satisfied, when the average thickness of the barrier layer is H [μm]. 4. The surface roughness of the surface of the first electrode on the side of the electron transport layer is adjusted by performing a smoothing treatment for reducing unevenness of the surface. Alternatively, the photoelectric conversion element according to item 3. 5. The photoelectric conversion element according to claim 1, wherein the smoothing treatment is polishing treatment and / or etching treatment. 6. The photoelectric conversion element according to claim 5, wherein the polishing process is performed using a polishing liquid containing a polishing agent. 7. The photoelectric conversion element according to claim 5, wherein the etching treatment is wet etching treatment, plasma etching treatment, or sputter etching treatment. 8. The photoelectric conversion element according to claim 1, wherein the barrier layer is formed by laminating on the smoothed surface. 9. The photoelectric conversion element according to claim 1, wherein the barrier layer is formed to have a porosity smaller than that of the electron transport layer. 10. When the porosity of the barrier layer is A [%] and the porosity of the electron transport layer is B [%], B is
The photoelectric conversion element according to claim 9, wherein / A is 1.1 or more. 11. The photoelectric conversion element according to claim 9, wherein the barrier layer has a porosity of 20% or less. 12. The photoelectric conversion element according to claim 1, wherein a thickness ratio of the barrier layer to the electron transport layer is 1:99 to 60:40. 13. The barrier layer has an average thickness of 0.01.
The photoelectric conversion element according to any one of claims 1 to 12, which has a thickness of 10 to 10 µm. 14. The photoelectric conversion element according to claim 1, wherein the barrier layer has electric conductivity equivalent to that of the electron transport layer. 15. The photoelectric conversion element according to claim 1, wherein the barrier layer is mainly composed of titanium oxide. 16. The photoelectric conversion element according to claim 1, wherein the barrier layer is formed by a MOD method. 17. The photoelectric conversion element according to claim 1, wherein a resistance value in a thickness direction of the entire barrier layer and the electron transport layer is 100 Ω / cm ² or more. 18. The photoelectric conversion element according to claim 1, wherein the barrier layer is located between the first electrode and the electron transport layer. 19. The photoelectric conversion element according to claim 18, wherein an interface between the barrier layer and the electron transport layer is unclear. 20. The barrier layer and the electron transport layer,
The photoelectric conversion element according to claim 18 or 19, which is integrally formed. 21. The photoelectric conversion element according to claim 1, wherein a part of the electron transport layer functions as the barrier layer. 22. The photoelectric conversion element according to claim 1, wherein the dye layer is a light-receiving layer that generates electrons and holes by receiving light. 23. The photoelectric conversion element according to claim 1, wherein the dye layer is formed along the outer surface of the electron transport layer and the inner surface of the pores. 24. The electron transport layer has a function of transporting electrons generated in at least the dye layer.
24. The photoelectric conversion element according to any one of 23 to 23. 25. The photoelectric conversion element according to claim 1, wherein the electron transport layer has a film shape. 26. The electron transport layer has an average thickness of 0.1.
The photoelectric conversion element according to any one of claims 1 to 25, which has a thickness of ˜300 μm. 27. The electron transport layer has a porosity of 5 to 90.
The photoelectric conversion element according to any one of claims 1 to 26, which is%. 28. At least a part of the electron transport layer comprises:
The photoelectric conversion element according to any one of claims 1 to 27, which is formed by using a powder of an electron transport layer material having an average particle diameter of 1 nm to 1 µm. 29. At least a part of the electron transport layer comprises:
The photoelectric conversion element according to any one of claims 1 to 28, which is formed by a sol-gel method using a sol liquid containing an electron transport layer material powder having an average particle diameter of 1 nm to 1 µm. 30. The content of the powder of the electron transport layer material in the sol liquid is 0.1 to 10% by weight.
The photoelectric conversion element described in 1. 31. The photoelectric conversion element according to claim 1, wherein the electron transport layer is mainly composed of titanium dioxide. 32. The photoelectric conversion element according to claim 1, wherein the hole transport layer is mainly composed of a substance having ionic conduction characteristics. 33. The substance having the ionic conduction property is
The photoelectric conversion element according to claim 32, which is a metal halide compound. 34. The photoelectric conversion element according to claim 33, wherein the metal halide compound is a metal iodide compound. 35. The hole transport layer is formed by applying a hole transport layer material containing a substance having the ion conductive property,
4. The coating is formed on the dye layer by coating.
The photoelectric conversion element according to any one of 2 to 34. 36. The photoelectric conversion element according to claim 35, wherein the hole transport layer material is applied onto the dye layer while heating the dye layer. 37. The photoelectric conversion element according to claim 35, wherein the hole transport layer material contains a substance for improving hole transport efficiency. 38. The photoelectric conversion element according to claim 37, wherein the substance is a halide. 39. The photoelectric conversion element according to claim 38, wherein the halide is ammonium halide. 40. The photoelectric conversion element according to claim 37, wherein the content of the substance in the hole transport layer material is 10 ⁻⁴ to 10 ⁻¹ wt%. 41. The photoelectric conversion element according to claim 1, further comprising a substrate that supports the first electrode. 42. The first electrode is positive and the second electrode is negative, and the resistance value is 100 Ω / cm ² or more when a voltage of 0.5 V is applied. Item 42. The photoelectric conversion element according to any one of Items 1 to 41. 43. The incident angle of light to the dye layer is 90 °
Photoelectric conversion efficiency of R ₉₀And the incident angle of light is 52 °
Photoelectric conversion efficiency is R₅₂And then R₅₂/ R₉₀But
43. The method according to claim 1, which is 0.8 or more.
Photoelectric conversion element. 44. The photoelectric conversion element according to claim 1, which is a solar cell.