WO2010090123A1

WO2010090123A1 - Organic photoelectric conversion element, solar cell using same, and optical sensor array

Info

Publication number: WO2010090123A1
Application number: PCT/JP2010/051119
Authority: WO
Inventors: 大久保　康; 野島　隆彦; 伊東　宏明; 晃矢子和地
Original assignee: コニカミノルタホールディングス株式会社
Priority date: 2009-02-04
Filing date: 2010-01-28
Publication date: 2010-08-12
Also published as: JPWO2010090123A1

Abstract

Disclosed is an organic thin film solar cell material, which has high solubility that enables the formation of a thick film, which is capable of improving the optical absorption, by a coating process. The organic thin film solar cell material exhibits a sufficient carrier transport ability even when formed into a thick film. The organic thin film solar cell material is characterized by being applied between a negative electrode and a positive electrode, and containing a compound having at least a partial structure represented by general formula (1). (In the formula, Z₁ represents a substituted or unsubstituted aromatic heterocyclic ring; Z₂ represents a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring; and R₁ represents a substituent selected from among a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group and a heteroaryl group.)

Description

Organic photoelectric conversion element, solar cell using the same, and optical sensor array

The present invention relates to an organic photoelectric conversion element, a solar cell, and an optical sensor array, and more particularly, to a bulk heterojunction type organic photoelectric conversion element, a solar cell using the organic photoelectric conversion element, and an optical array sensor.

Due to the recent rise in fossil energy, a system that can generate electric power directly from natural energy has been demanded. Solar cells using monocrystalline, polycrystalline, or amorphous Si, compound-based solar cells such as GaAs and CIGS, or Dye-sensitized photoelectric conversion elements (Gretzel cells) have been proposed and put into practical use.

However, the cost of generating electricity with these solar cells is still higher than the price of electricity generated and transmitted using fossil fuels, which has hindered widespread use. In addition, since heavy glass must be used for the substrate, reinforcement work is required at the time of installation, which is one of the causes that increase the power generation cost.

In this situation, as a solar cell that can achieve a power generation cost lower than that of fossil fuel, an electron donor layer (p-type semiconductor layer) and an electron acceptor layer ( A bulk heterojunction photoelectric conversion element having a bulk heterojunction layer mixed with an n-type semiconductor layer has been proposed (for example, see Non-Patent Document 1).

These bulk heterojunction solar cells are formed by a coating process except for the anode and cathode, and are expected to be able to be manufactured at high speed and at low cost. There is. Furthermore, unlike the Si solar cells, compound semiconductor solar cells, and dye-sensitized solar cells described above, there is no process at a temperature higher than 160 ° C., so it can be formed on a cheap and lightweight plastic substrate. Is done.

In addition to the initial manufacturing cost, the power generation cost must be calculated including the power generation efficiency and the durability of the element. In Non-Patent Document 1, in order to efficiently absorb the solar spectrum, a long wavelength is used. By using an organic polymer capable of absorbing up to 5%, conversion efficiency exceeding 5% has been achieved.

The photoelectric conversion efficiency is calculated by the product of short-circuit current density (Jsc) × open-circuit voltage (Voc) × curve factor (FF), and generally includes organic photoelectric conversion including high-efficiency organic thin-film solar cells as described above. The device has only a low fill factor of about 0.55, and if these can be improved to values comparable to silicon solar cells (0.65 to 0.75), further photoelectric conversion efficiency is expected. The

The curve factor is closely related to the internal resistance of the photoelectric conversion element, and it is known that lowering the resistance of the organic thin film and improving the charge separation efficiency (improving rectification) are effective for improving the curve factor. Yes.

There is a disclosure that the charge separation efficiency can be improved and the photoelectric conversion efficiency can be improved by inserting a hole blocking layer made of bathocuproine (BCP) as in the organic EL element (see, for example, Patent Document 1). Since these materials have high crystallinity and low solubility, there is a problem that it is difficult to apply them to a coating method with high productivity.

Further, although a TiOx layer is disclosed as a hole blocking layer that can be produced by a coating process (see, for example, Non-Patent Document 2), in order to form a TiOx layer, it is necessary to react moisture with titanium alkoxides. An organic photoelectric conversion element that is deteriorated by moisture is not a preferable manufacturing method, and has a problem in durability.

In addition, in an organic electroluminescence device (OLED) having a similar structure but having the opposite function, a carboline derivative or a diazacarbazole derivative is used for the hole blocking layer in order to improve the light emission efficiency. Although there is a disclosure (see, for example, Patent Documents 2 and 3), generally, whether a hole blocking layer functions as a hole blocking layer is determined by the relationship with the HOMO level of an adjacent layer. Any block layer is not necessarily applicable to an organic photoelectric conversion element, and in particular, since the HOMO and LUMO of a fullerene derivative which is an n-type semiconductor contained in a bulk heterojunction layer are relatively deep, the organic photoelectric conversion element The development of a hole blocking layer that can be effectively formed by a non-aqueous coating method is also awaited. It had.

In addition to the fill factor, it is necessary to obtain a high open-circuit voltage in order to obtain a high photoelectric conversion efficiency. Generally, the open-circuit voltage is a HOMO level of a p-type semiconductor material used for a bulk heterojunction layer and an n-type semiconductor. It is said that there is a correlation with the difference from the LUMO level of the material, and it is considered that the higher this value, the higher the open circuit voltage.

For example, Non-Patent Document 3 proposes an organic photoelectric conversion element using a carbazole derivative in a bulk heterojunction layer, and an open circuit voltage as high as 0.89 V is obtained. On the other hand, the compound of Non-Patent Document 4 having a structure in which the carbazole structure is converted into a thiophenecarbazole derivative has been able to absorb a longer wave wavelength by reducing the band gap, but the HOMO level has become shallower. The open circuit voltage is reduced by 0.52 V, and the photoelectric conversion efficiency is low.

Therefore, if an azacarbazole derivative which is a nitrogen-containing aromatic six-membered ring having a deep HOMO level as in the present invention can be used as a semiconductor material for a bulk heterojunction layer, higher open-circuit voltage and photoelectric conversion efficiency can be obtained. It is estimated to be.

US Pat. No. 6,658,0027 B2 International Publication No. 2004-053019 International Publication No. 2004-095889

An object of the present invention is to provide an organic thin-film solar cell having high fill factor, open-circuit voltage, photoelectric conversion efficiency, and durability, and an organic semiconductor material constituting the organic thin-film solar cell.

The above object of the present invention can be achieved by the following configuration.

1. An organic photoelectric conversion element having a cathode, an anode, and a bulk heterojunction layer in which a p-type semiconductor material and an n-type semiconductor material are mixed, and is represented by at least the following general formula (1) between the cathode and the anode. An organic photoelectric conversion device comprising a layer containing a compound having a partial structure.

(In the formula, Z ₁ represents a substituted or unsubstituted nitrogen-containing aromatic 6-membered ring, Z ₂ represents a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring. R ₁ represents a hydrogen atom, halogen, This represents a substituent selected from an atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group.
2. 2. The organic photoelectric conversion according to 1 above, wherein a layer containing a compound having a partial structure represented by the general formula (1) is present between the bulk heterojunction layer and the cathode. element.

3. 2. The organic photoelectric conversion device according to 1 above, wherein the layer containing the compound having a partial structure represented by the general formula (1) is a bulk heterojunction layer.

4. 4. The organic photoelectric conversion device as described in any one of 1 to 3 above, which comprises a compound having two or more partial structures represented by the general formula (1) in the molecule.

5. Any one of the above 1 to 4, wherein the compound having a partial structure represented by the general formula (1) is a compound having a partial structure represented by the following general formula (2a) or (2b): 2. The organic photoelectric conversion element according to item 1.

(Wherein X ₁ to X ₄ represent a substituted or unsubstituted carbon atom or a nitrogen atom. Z ₃ represents a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring. R ₂ represents a hydrogen atom, It represents a substituent selected from a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group.)
6). 6. The organic photoelectric conversion according to any one of 1 to 5 above, wherein the aromatic heterocycle represented by Z ₂ in the general formula (1) is a nitrogen-containing aromatic 6-membered ring element.

7. Any one of 1 to 6 above, wherein the compound having a partial structure represented by the general formula (1) is a compound having a partial structure represented by the following general formula (3a) or (3b): 2. The organic photoelectric conversion element according to item 1.

(Wherein R ₃ represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, or a heteroaryl group. X ₅ to X ₈ are substituted or unsubstituted. Represents a carbon atom or a nitrogen atom.)
8). 8. The compound according to any one of 1 to 7, wherein the compound having a partial structure represented by the general formula (1) is a compound having a partial structure represented by the following general formula (4): Organic photoelectric conversion element.

(Wherein R ₄ to R ₁₀ represent a substituent selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group.)
9. 9. The compound according to any one of 1 to 8 above, wherein the compound having a partial structure represented by the general formula (1) is a compound having a partial structure represented by the following general formula (5). Organic photoelectric conversion element.

(Wherein R ₁₁ to R ₁₃ represent a substituent selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group. Z ₄ represents a substituted or unsubstituted group. A nitrogen-containing aromatic ring, Z ₅ represents a substituted or unsubstituted aromatic ring and a heteroaromatic ring, p represents an integer of 0 to 4 and q represents an integer of 2 to 6)
10. The compound having a partial structure represented by the general formula (1), (2a), (2b), (3a), (3b), (4) or (5) is a low molecular weight compound having a molecular weight of less than 5000. 10. The organic photoelectric conversion element as described in any one of 1 to 9 above, wherein

11. 11. The compound according to any one of 1 to 10 above, wherein the compound having a partial structure represented by the general formula (1) is a compound having a partial structure represented by the following general formula (6). Organic photoelectric conversion element.

(Wherein R ₁₄ to R ₁₆ represent a substituent selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group. Z ₆ represents a substituted or unsubstituted group. A nitrogen-containing aromatic ring, Z ₇ represents a substituted or unsubstituted aromatic ring and a heteroaromatic ring, r represents an integer of 0 to 4, and s represents an integer of 2 to 10,000)
12 12. The organic photoelectric conversion device as described in 11 above, wherein the compound having a partial structure represented by the general formula (6) is a polymer compound having a molecular weight of 5000 or more.

13. A layer containing a compound having a partial structure represented by the general formula (1), (2a), (2b), (3a), (3b), (4), (5), or (6), 13. The organic photoelectric conversion element as described in any one of 1 to 12 above, which is produced by a solution coating method.

14. 14. A solar cell using the organic photoelectric conversion device as described in any one of 1 to 13 above.

15. 14. An optical sensor array comprising the organic photoelectric conversion elements according to any one of 1 to 13 arranged in an array.

According to the present invention, an organic thin-film solar cell material that can achieve a high photoelectric conversion efficiency, has high durability, and can be applied to a coating process that enables inexpensive manufacturing can be provided.

It is sectional drawing which shows the solar cell which consists of a bulk hetero junction type organic photoelectric conversion element. 1 is a cross-sectional view showing a solar cell composed of an organic photoelectric conversion element including a photoelectric conversion layer having a three-layer structure of pin. It is sectional drawing which shows the solar cell which consists of an organic photoelectric conversion element provided with a tandem-type bulk heterojunction layer. It is a figure which shows the structure of an optical sensor array.

As a result of diligent investigations on the above-mentioned problems, the present inventors can achieve the above-mentioned problems because the layer containing the compound represented by the general formula (1) exists between the cathode and the anode. I found. Furthermore, the effect appears more remarkably when a layer containing the compound represented by the general formula (2) or (3) is present between the bulk heterojunction layer and the cathode.

Hereinafter, the present invention will be described in more detail.

(Configuration of organic photoelectric conversion element and solar cell)
FIG. 1 is a cross-sectional view showing an example of a solar cell composed of a bulk heterojunction organic photoelectric conversion element. In FIG. 1, a bulk heterojunction type organic photoelectric conversion element 10 includes a transparent electrode (generally an anode) 12, a hole transport layer 17, a bulk heterojunction layer photoelectric conversion unit 14, and an electron transport layer 18 on one surface of a substrate 11. And a counter electrode (generally a cathode) 13 are sequentially stacked.

The substrate 11 is a member that holds the transparent electrode 12, the photoelectric conversion unit 14, and the counter electrode 13 that are sequentially stacked. In the present embodiment, since light that is photoelectrically converted enters from the substrate 11 side, the substrate 11 can transmit the light that is photoelectrically converted, that is, with respect to the wavelength of the light to be photoelectrically converted. It is a transparent member. As the substrate 11, for example, a glass substrate or a resin substrate is used. The substrate 11 is not essential. For example, the bulk heterojunction type organic photoelectric conversion element 10 may be configured by forming the transparent electrode 12 and the counter electrode 13 on both surfaces of the photoelectric conversion unit 14.

The photoelectric conversion unit 14 is a layer that converts light energy into electric energy, and includes a bulk heterojunction layer in which a p-type semiconductor material and an n-type semiconductor material are uniformly mixed. The p-type semiconductor material functions relatively as an electron donor (donor), and the n-type semiconductor material functions relatively as an electron acceptor (acceptor). Here, the electron donor and the electron acceptor are “an electron donor in which, when light is absorbed, electrons move from the electron donor to the electron acceptor to form a hole-electron pair (charge separation state)”. And an electron acceptor ”, which does not simply donate or accept electrons like an electrode, but donates or accepts electrons by a photoreaction.

In FIG. 1, light incident from the transparent electrode 12 through the substrate 11 is absorbed by the electron acceptor or electron donor in the bulk heterojunction layer of the photoelectric conversion unit 14, and electrons move from the electron donor to the electron acceptor. Thus, a hole-electron pair (charge separation state) is formed. The generated electric charge is caused by an internal electric field, for example, when the work functions of the transparent electrode 12 and the counter electrode 13 are different, the electrons pass between the electron acceptors due to the potential difference between the transparent electrode 12 and the counter electrode 13, and the holes are The photocurrent is detected as it passes between the donors and is carried to different electrodes. For example, when the work function of the transparent electrode 12 is larger than the work function of the counter electrode 13, electrons are transported to the transparent electrode 12 and holes are transported to the counter electrode 13. If the magnitude of the work function is reversed, electrons and holes are transported in the opposite direction. In addition, by applying a potential between the transparent electrode 12 and the counter electrode 13, the transport direction of electrons and holes can be controlled.

Although not shown in FIG. 1, other layers such as a hole blocking layer, an electron blocking layer, an electron injection layer, a hole injection layer, or a smoothing layer may be included.

More preferably, the photoelectric conversion unit 14 has a so-called pin three-layer structure (FIG. 2). A normal bulk heterojunction layer is a 14i layer composed of a mixture of a p-type semiconductor material and an n-type semiconductor layer, but a 14p layer composed of a single p-type semiconductor material and a 14n layer composed of a single n-type semiconductor material. By sandwiching, the rectification of holes and electrons becomes higher, loss due to recombination of charge-separated holes and electrons is reduced, and higher photoelectric conversion efficiency can be obtained.

Furthermore, for the purpose of improving the sunlight utilization rate (photoelectric conversion efficiency), a tandem configuration in which such photoelectric conversion elements are stacked may be employed. FIG. 3 is a cross-sectional view showing a solar cell composed of an organic photoelectric conversion element including a tandem bulk heterojunction layer. In the case of the tandem configuration, the transparent electrode 12 and the first photoelectric conversion unit 14 ′ are sequentially stacked on the substrate 11, the charge recombination layer 15 is stacked, the second photoelectric conversion unit 16, and then the counter electrode. By stacking 13, a tandem configuration can be obtained. The second photoelectric conversion unit 16 may be a layer that absorbs the same spectrum as the absorption spectrum of the first photoelectric conversion unit 14 'or may be a layer that absorbs a different spectrum, but is preferably a layer that absorbs a different spectrum. is there. Further, both the first photoelectric conversion unit 14 ′ and the second photoelectric conversion unit 16 may have the above-described three-layer structure of pin.

The materials that make up these layers are described below. In the present invention, the compound having the partial structure represented by the general formula (1) is included between the cathode and the anode. The layer containing the partial structure represented by the general formula (1) is preferably a bulk heterojunction layer. The layer containing the partial structure represented by the general formula (1) is also preferably an electron transport layer.

[P-type semiconductor materials]
Examples of the p-type semiconductor material used for the bulk heterojunction layer of the present invention include various condensed polycyclic aromatic low molecular compounds and conjugated polymers.

Examples of the condensed polycyclic aromatic low molecular weight compound include anthracene, tetracene, pentacene, hexacene, heptacene, chrysene, picene, fluorene, pyrene, peropyrene, perylene, terylene, quaterylene, coronene, ovalene, circumanthanthene, bisanthene, zeslene. , Heptazethrene, pyranthrene, violanthene, isoviolanthene, circobiphenyl, anthradithiophene, etc., porphyrin, copper phthalocyanine, tetrathiafulvalene (TTF) -tetracyanoquinodimethane (TCNQ) complex, bisethylenetetrathiafulvalene ( BEDTTTTF) -perchloric acid complexes, and derivatives and precursors thereof.

Examples of the derivative having the above condensed polycycle include WO 03/16599 pamphlet, WO 03/28125 pamphlet, US Pat. No. 6,690,029, JP 2004-107216 A. A pentacene derivative having a substituent described in JP-A No. 2003-136964, a pentacene precursor described in US Patent Application Publication No. 2003/136964, and the like; Amer. Chem. Soc. , Vol127. No. 14.4986, J.H. Amer. Chem. Soc. , Vol. 123, p9482; Amer. Chem. Soc. , Vol. 130 (2008), no. 9, acene-based compounds substituted with a trialkylsilylethynyl group described in 2706 and the like.

As the conjugated polymer, for example, a polythiophene such as poly-3-hexylthiophene (P3HT) and an oligomer thereof, or a technical group described in Technical Digest of the International PVSEC-17, Fukuoka, Japan, 2007, P1225. Polythiophene, Nature Material, (2006) vol. 5, p328, a polythiophene-thienothiophene copolymer described in WO2008000664, a polythiophene-diketopyrrolopyrrole copolymer described in WO2008000664, a polythiophene-thiazolothiazole copolymer described in Adv Mater, 2007p4160, Nature Mat. vol. 6 (2007), p497 described in PCPDTBT, etc., polypyrrole and its oligomer, polyaniline, polyphenylene and its oligomer, polyphenylene vinylene and its oligomer, polythienylene vinylene and its oligomer, polyacetylene, polydiacetylene, Examples thereof include polymer materials such as σ-conjugated polymers such as polysilane and polygermane.

In addition, oligomeric materials, not polymer materials, include thiophene hexamer α-seccithiophene α, ω-dihexyl-α-sexualthiophene, α, ω-dihexyl-α-kinkethiophene, α, ω-bis (3 Oligomers such as -butoxypropyl) -α-sexithiophene can be preferably used.

Among these compounds, compounds that are highly soluble in an organic solvent to the extent that a solution process can be performed, can form a crystalline thin film after drying, and can achieve high mobility are preferable. More preferably, it is a compound (a compound capable of forming an appropriate phase separation structure) having appropriate compatibility with the fullerene derivative which is the n-type organic semiconductor material of the present invention.

In addition, when forming an electron transport layer or a hole blocking layer by a solution process on the bulk heterojunction layer, if it can be further applied on the layer once applied, it can be easily laminated, When a layer is further laminated by a solution process on a layer made of a material that usually has good solubility, there is a problem that the layer cannot be laminated because the underlying layer is dissolved. Therefore, a material that can be insolubilized after application by a solution process is preferable.

Examples of such materials include materials that can be insolubilized by polymerizing the coating film after coating, such as polythiophene having a polymerizable group described in Technical Digest of the International PVSEC-17, Fukuoka, Japan, 2007, P1225. Or a material in which soluble substituents react and become insoluble (pigmented) by applying energy such as heat, as described in US Patent Application Publication No. 2003/136964, and Japanese Patent Application Laid-Open No. 2008-16834 And so on.

Among these, a compound having a partial structure represented by the general formula (1) is used in the present invention.

In the general formula (1), Z ₁ represents a substituted or unsubstituted nitrogen-containing aromatic 6-membered ring, and Z ₂ represents a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring. R ₁ represents a substituent selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group.

The structure represented by the general formula (1) has a deep HOMO level, and an element having a high open-circuit voltage can be obtained. Among them, a material having a plurality of these structures is effective.

The nitrogen-containing aromatic six-membered ring represented by Z ₁ in the general formula (1) preferably has a nitrogen atom number range of 1 to 3, but in order to obtain a high open circuit voltage, a carbon atom of the carbazole ring A higher open circuit voltage can be obtained by substituting with more nitrogen atoms. On the other hand, since the stability of the compound is lowered, in order to achieve both high open-circuit voltage and stability of the compound, a heteroaromatic ring containing one nitrogen atom for each of the aromatic rings of Z ₁ and Z ₂ is used. It is preferable. Further, the position occupied by the nitrogen atom in Z ₁ of the general formula (1) is a deep HOMO quasi-state when the α-position, β-position, γ-position, and δ-position from the side close to the nitrogen atom of the central nitrogen-containing 5-membered ring. From the viewpoint of obtaining a compound at the position, the γ-position and the δ-position are preferable, and thus a structure represented by the general formula (2a) or (2b) is more preferable.

In the general formula (2a) or (2b), X ₁ to X _{4 each} represent a substituted or unsubstituted carbon atom or nitrogen atom. R ₂ represents a substituent selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group. Z ₃ represents a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring.

The aromatic ring represented by Z ₃ is also preferably an aromatic 6-membered ring capable of forming a symmetric structure in order to make the obtained p-type semiconductor material highly crystalline and to have a high mobility. And more preferably a nitrogen-containing aromatic 6-membered ring. In this case as well, the γ-position and the δ-position are preferred as the position where the nitrogen atom is substituted, but in particular, the structure is such that the nitrogen atom is substituted at the γ-position or δ-position of both aromatic rings represented by Z ₁ and Z _2. Things are preferable. Furthermore, it is preferable that Z ₁ and Z ₂ have the same and symmetrical structure. That is, a compound represented by the general formula (3a) or (3b) is preferable.

In the general formula (3a) or (3b), R ₃ represents a substituent selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group. X ₅ to X _{8 each} represents a substituted or unsubstituted carbon atom or nitrogen atom.

More preferably, the p-type semiconductor material has a diazacarbazole structure in which nitrogen is located at the γ-position where the compound has high symmetry and stability, and the HOMO level is deep and the open circuit voltage (Voc) can be improved. 4).

In the general formula (4), R ₄ to R ₁₀ represent a substituent selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group.

The p-type semiconductor material is more preferably a compound that can absorb a long wavelength of about 800 to 1200 nm so that a wider sunlight spectrum can be used, and therefore has a structure in which the conjugate length of π electrons is as long as possible. It is preferable. That is, the compound represented by the general formula (6) is preferable.

In the general formula (6), R ₁₄ to R ₁₆ represent a substituent selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group. Z ₆ represents a substituted or unsubstituted nitrogen-containing aromatic ring, and Z ₇ represents a substituted or unsubstituted aromatic ring or heteroaromatic ring. r represents an integer of 0 to 4, and s represents an integer of 2 to 10,000.

Specific examples of the compounds represented by the general formulas (1), (2a), (2b), (3a), (3b), (4), (5) and (6) of the present invention will be given below. The present invention is not limited to these.

In the above compounds 29, 30, and 101 to 117, n represents 10 to 100.

In the present invention, the bulk heterojunction layer increases the interface area between the p-type semiconductor material and the n-type semiconductor material as much as possible so that the charge separation efficiency is sufficiently high, while the holes and electrons generated at the interface are reduced. It is necessary to have a continuous phase separation structure so that the extraction electrode can be extracted. In order to form such an appropriate phase separation structure simply by coating, the p-type semiconductor material is preferably a polymer compound.

In the present invention, the low molecular weight compound means a single molecule having no distribution in the molecular weight of the compound. On the other hand, the polymer compound means an aggregate of compounds having a certain molecular weight distribution by reacting a predetermined monomer. However, when defining by molecular weight in practice, a compound having a molecular weight of 5000 or more is classified as a polymer compound. More preferably, it is 10,000 or more, More preferably, it is 30000 or more. On the other hand, since the solubility decreases as the molecular weight increases, the molecular weight is preferably 1,000,000 or less, more preferably 100,000 or less. The molecular weight can be measured by gel permeation chromatography (GPC).

The compound having such a structure according to the present invention is disclosed in Patent Documents 1 and 2 or Tetrahedron vol. 51, no. 44 (1995), p12127 and the like can be synthesized.

[N-type semiconductor materials]
The n-type semiconductor material used in the bulk heterojunction layer of the present invention is not particularly limited. For example, a perfluoro compound (perfluoro compound) in which hydrogen atoms of a p-type semiconductor such as fullerene and octaazaporphyrin are substituted with fluorine atoms. Pentacene, perfluorophthalocyanine, etc.), naphthalenetetracarboxylic anhydride, naphthalenetetracarboxylic acid diimide, perylenetetracarboxylic acid anhydride, perylenetetracarboxylic acid diimide and other aromatic carboxylic acid anhydrides and imidized compounds thereof. Examples thereof include molecular compounds.

However, fullerene derivatives that can perform charge separation with various p-type semiconductor materials at high speed (up to 50 fs) and efficiently are preferable. Fullerene derivatives include fullerene C60, fullerene C70, fullerene C76, fullerene C78, fullerene C84, fullerene C240, fullerene C540, mixed fullerene, fullerene nanotubes, multi-walled nanotubes, single-walled nanotubes, nanohorns (conical), etc. Partially by hydrogen atom, halogen atom, substituted or unsubstituted alkyl group, alkenyl group, alkynyl group, aryl group, heteroaryl group, cycloalkyl group, silyl group, ether group, thioether group, amino group, silyl group, etc. Examples thereof include substituted fullerene derivatives.

Among them, [6,6] -phenyl C61-butyric acid methyl ester (abbreviation PCBM), [6,6] -phenyl C61-butyric acid-n-butyl ester (PCBnB), [6,6] -phenyl C61-buty Rick acid-isobutyl ester (PCBiB), [6,6] -phenyl C61-butyric acid-n-hexyl ester (PCBH), Adv. Mater. , Vol. 20 (2008), p2116, etc., aminated fullerenes such as JP-A 2006-199674, metallocene fullerenes such as JP-A 2008-130889, and cyclics such as US Pat. No. 7,329,709. It is preferable to use a fullerene derivative having a substituent and having improved solubility, such as fullerene having an ether group.

[Method of forming bulk heterojunction layer]
Examples of a method for forming a bulk heterojunction layer in which an electron acceptor and an electron donor are mixed include a vapor deposition method and a coating method (including a casting method and a spin coating method). Among these, the coating method is preferable in order to increase the area of the interface where charges and electrons are separated from each other as described above and to produce a device having high photoelectric conversion efficiency. The coating method is also excellent in production speed.

After application, it is preferable to perform heating in order to cause removal of residual solvent, moisture, and gas, and improvement of mobility and absorption of long wave by crystallization of the semiconductor material. When annealing is performed at a predetermined temperature during the manufacturing process, a part of the particles is microscopically aggregated or crystallized, and the bulk heterojunction layer can have an appropriate phase separation structure. As a result, the carrier mobility of the bulk heterojunction layer is improved and high efficiency can be obtained.

The photoelectric conversion part (bulk heterojunction layer) 14 may be composed of a single layer in which the electron acceptor and the electron donor are uniformly mixed, but a plurality of the mixture ratios of the electron acceptor and the electron donor are changed. It may consist of layers. In this case, it can be formed by using a material that can be insolubilized after coating as described above.

[Electron transport layer (hole blocking layer)]
The organic photoelectric conversion element 10 of the present invention can extract charges generated in the bulk heterojunction layer more efficiently by forming the electron transport layer 18 between the bulk heterojunction layer and the cathode. Therefore, it is preferable to have these layers.

The electron transport layer is a layer that is located between the cathode and the bulk heterojunction layer and can transfer electrons between the bulk heterojunction layer and the electrode more efficiently. is there. More specifically, a compound having an LUMO level intermediate between the LUMO level of the n-type semiconductor material of the bulk hetero junction layer and the work function of the cathode is suitable as the electron transporting layer. More preferably, it is a compound having an electron mobility of 10 ⁻⁴ or more.

As the electron transport layer (hole blocking layer) 18, octaazaporphyrin and a p-type semiconductor perfluoro compound (perfluoropentacene, perfluorophthalocyanine, etc.) can be used. Similarly, in the bulk heterojunction layer. The electron transport layer having a HOMO level deeper than the HOMO level of the p-type semiconductor material used has a rectifying effect that prevents holes generated in the bulk heterojunction layer from flowing to the cathode side. Block function is added. Such an electron transport layer is also referred to as a hole blocking layer. More preferably, a material deeper than the HOMO level of the n-type semiconductor is used as the electron transport layer. Moreover, it is preferable to use a compound with high electron mobility from the characteristic of transporting electrons.

Examples of such materials include phenanthrene compounds such as bathocuproine, n-type semiconductor materials such as naphthalenetetracarboxylic acid anhydride, naphthalenetetracarboxylic acid diimide, perylenetetracarboxylic acid anhydride, perylenetetracarboxylic acid diimide, and titanium oxide. N-type inorganic oxides such as zinc oxide and gallium oxide, and alkali metal compounds such as lithium fluoride, sodium fluoride, and cesium fluoride can be used. A layer made of a single n-type semiconductor material used for the bulk heterojunction layer can also be used.

In the present invention, the HOMO level is deep and the electron mobility is high, and the general formulas (1), (2a), (2b), (3a), (3b), (4), and (6) of the present invention are used. By using the compound to be used as an electron transporting layer (also serving as a hole blocking layer), effects such as an improvement in fill factor and photoelectric conversion efficiency can be obtained.

More preferably, the structure is represented by the general formula (5). By setting it as the compound of such a structure, it can design to the compound which has the above LUMO levels and HOMO levels, and can be set as a more efficient organic thin-film solar cell.

In the general formula (5), R ₁₁ to R ₁₃ represent a substituent selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group. Z ₄ represents a substituted or unsubstituted nitrogen-containing aromatic ring. Z ₅ represents a substituted or unsubstituted aromatic ring and heteroaromatic ring. p represents an integer of 0 to 4, and q represents an integer of 2 to 6.

The nitrogen-containing heterocycle represented by Z ₄ is more preferably a substituted or unsubstituted imidazole, pyrazole, triazole, oxazole, thiazole, oxadiazole, thiadiazole, benzimidazole, benzooxadiazole, benzothiadiazole. Benzotriazole, pyridothiadiazole, thienopyrazine, pyrrolopyrazine, thiazolothiazole, pyridazine, pyrimidine, pyrazine, triazine, quinoline, quinoxaline and the like.

Among these, a substituent having a strong electron-withdrawing property having a plurality of nitrogen atoms is preferable, and among them, benzoxadiazole, benzothiadiazole, pyridothiadiazole, thienopyrazine, and the like are preferable. Most preferred are benzoxadiazole and benzothiadiazole.

In addition, unlike the bulk heterojunction layer, the electron transport layer is a layer of a single electron transport material, and there is no need to consider the morphology of the mixed state. In view of obtaining a thin film having a sufficient degree, the electron transport material is preferably a low molecular compound. In the present invention, the low molecular weight compound means a single molecule having no distribution in the molecular weight of the compound. On the other hand, the polymer compound means an aggregate of compounds having a certain molecular weight distribution by reacting a predetermined monomer. However, when defining by molecular weight in practice, a compound having a molecular weight of less than 5000 is classified as a low molecular weight compound. More preferably, it is 3000 or less, More preferably, it is 1500 or less. The molecular weight can be measured by gel permeation chromatography (GPC).

The means for forming these layers may be either a vacuum vapor deposition method or a solution coating method, but is preferably a solution coating method.

[Hole transport layer (electron blocking layer)]
In the organic photoelectric conversion element 10 of the present invention, the hole transport layer 17 is provided between the bulk heterojunction layer and the anode, and charges generated in the bulk heterojunction layer can be taken out more efficiently. It is preferable to have these layers.

As a material constituting these layers, for example, as the hole transport layer 17, PEDOT such as trade name BaytronP, polyaniline and its doped material, cyan compounds described in WO2006019270, etc. Can be used. Note that electrons generated in the bulk heterojunction layer do not flow to the anode side in the hole transport layer having a LUMO level shallower than the LUMO level of the n-type semiconductor material used for the bulk heterojunction layer. An electronic block function having a rectifying effect is provided. Such a hole transport layer is also called an electron block layer, and it is preferable to use a hole transport layer having such a function. As such materials, triarylamine compounds described in JP-A-5-271166, metal oxides such as molybdenum oxide, nickel oxide, and tungsten oxide can be used. Moreover, the layer which consists of a p-type semiconductor material single-piece | unit used for the bulk heterojunction layer can also be used. The means for forming these layers may be either a vacuum deposition method or a solution coating method, but is preferably a solution coating method. Forming the coating film in the lower layer before forming the bulk heterojunction layer is preferable because it has the effect of leveling the coating surface and reduces the influence of leakage and the like.

[Other layers]
For the purpose of improving energy conversion efficiency and improving the lifetime of the element, a structure having various intermediate layers in the element may be employed. Examples of the intermediate layer include a hole block layer, an electron block layer, a hole injection layer, an electron injection layer, an exciton block layer, a UV absorption layer, a light reflection layer, and a wavelength conversion layer.

<electrode>
The photoelectric conversion element according to the present invention has at least an anode and a cathode. Further, when a tandem configuration is adopted, the tandem configuration can be achieved by using an intermediate electrode. In the present invention, an electrode through which holes mainly flow is called an anode, and an electrode through which electrons mainly flow is called a cathode.

Also, there is a case where a translucent electrode is referred to as a transparent electrode and a non-translucent electrode is referred to as a counter electrode because of the function of whether or not it has translucency. Usually, the anode is a translucent transparent electrode, and the cathode is a non-translucent counter electrode.

〔anode〕
The anode of the present invention is preferably an electrode that transmits light of 380 to 800 nm. As the material, for example, transparent conductive metal oxides such as indium tin oxide (ITO), SnO ₂ and ZnO, metal thin films such as gold, silver and platinum, metal nanowires and carbon nanotubes can be used.

Also, a conductive material selected from the group consisting of polypyrrole, polyaniline, polythiophene, polythienylene vinylene, polyazulene, polyisothianaphthene, polycarbazole, polyacetylene, polyphenylene, polyphenylene vinylene, polyacene, polyphenylacetylene, polydiacetylene and polynaphthalene. A functional polymer can also be used. Further, a plurality of these conductive compounds can be combined to form an anode.

〔cathode〕
The cathode may be a single layer of a conductive material, but in addition to a conductive material, a resin that holds these may be used in combination. As a conductive material for the cathode, a material having a work function (4 eV or less) metal, alloy, electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) Mixtures, indium, lithium / aluminum mixtures, rare earth metals and the like. Among these, from the viewpoint of electron extraction performance and durability against oxidation, etc., a mixture of these metals and a second metal which is a stable metal having a larger work function value than this, for example, a magnesium / silver mixture, magnesium / Aluminum mixtures, magnesium / indium mixtures, aluminum / aluminum oxide (Al ₂ O ₃ ) mixtures, lithium / aluminum mixtures, aluminum and the like are preferred. The cathode can be produced by forming a thin film of these electrode materials by a method such as vapor deposition or sputtering. The film thickness is usually selected in the range of 10 nm to 5 μm, preferably 50 to 200 nm.

If a metal material is used as the conductive material of the cathode, the light coming to the cathode side is reflected and reflected to the first electrode side, and this light can be reused and absorbed again by the photoelectric conversion layer, further improving the photoelectric conversion efficiency. It is preferable.

Further, the cathode 13 may be a metal (for example, gold, silver, copper, platinum, rhodium, ruthenium, aluminum, magnesium, indium, etc.), a nanoparticle made of carbon, a nanowire, or a nanostructure. A dispersion is preferable because a transparent and highly conductive cathode can be formed by a coating method.

Further, when the cathode side is made light transmissive, for example, a conductive material suitable for the cathode such as aluminum and aluminum alloy, silver and silver compound is made thin with a film thickness of about 1 to 20 nm, and then the anode By providing a film of the conductive light-transmitting material mentioned in the description, a light-transmitting cathode can be obtained.

[Intermediate electrode]
The intermediate electrode material required in the case of the tandem structure as shown in FIG. 3 is preferably a layer using a compound having both transparency and conductivity. Transparent metal oxides such as ITO, AZO, FTO and titanium oxide, very thin metal layers such as Ag, Al and Au, or layers containing nanoparticles / nanowires, conductive polymer materials such as PEDOT: PSS and polyaniline Etc.) can be used.

In addition, in the hole transport layer and the electron transport layer described above, there is also a combination that works as an intermediate electrode (charge recombination layer) by appropriately combining and laminating, and with such a configuration, the process of forming one layer This is preferable because it can be omitted.

〔substrate〕
When light that is photoelectrically converted enters from the substrate side, the substrate is preferably a member that can transmit the light that is photoelectrically converted, that is, a member that is transparent to the wavelength of the light to be photoelectrically converted. As the substrate, for example, a glass substrate, a resin substrate and the like are preferably mentioned, but it is desirable to use a transparent resin film from the viewpoint of light weight and flexibility. There is no restriction | limiting in particular in the transparent resin film which can be preferably used as a transparent substrate by this invention, The material, a shape, a structure, thickness, etc. can be suitably selected from well-known things. For example, polyester resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) modified polyester, polyethylene (PE) resin film, polypropylene (PP) resin film, polystyrene resin film, polyolefin resins such as cyclic olefin resin Film, vinyl resin film such as polyvinyl chloride, polyvinylidene chloride, polyether ether ketone (PEEK) resin film, polysulfone (PSF) resin film, polyether sulfone (PES) resin film, polycarbonate (PC) resin film, A polyamide resin film, a polyimide resin film, an acrylic resin film, a triacetyl cellulose (TAC) resin film, and the like can be given. If the resin film transmittance of 80% or more in ~ 800 nm), can be preferably applied to a transparent resin film according to the present invention. Among these, from the viewpoint of transparency, heat resistance, ease of handling, strength and cost, it is preferably a biaxially stretched polyethylene terephthalate film, a biaxially stretched polyethylene naphthalate film, a polyethersulfone film, or a polycarbonate film, and biaxially stretched. A polyethylene terephthalate film and a biaxially stretched polyethylene naphthalate film are more preferable.

The transparent substrate used in the present invention can be subjected to a surface treatment or an easy adhesion layer in order to ensure the wettability and adhesion of the coating solution. A conventionally well-known technique can be used about a surface treatment or an easily bonding layer. For example, the surface treatment includes surface activation treatment such as corona discharge treatment, flame treatment, ultraviolet treatment, high frequency treatment, glow discharge treatment, active plasma treatment, and laser treatment. Examples of the easy adhesion layer include polyester, polyamide, polyurethane, vinyl copolymer, butadiene copolymer, acrylic copolymer, vinylidene copolymer, and epoxy copolymer.

Further, for the purpose of suppressing the permeation of oxygen and water vapor, a barrier coat layer may be formed in advance on the transparent substrate, or a hard coat layer may be formed in advance on the opposite side to which the transparent conductive layer is transferred. Good.

(Optical function layer)
The organic photoelectric conversion element of the present invention may have various optical functional layers for the purpose of more efficient reception of sunlight. As the optical functional layer, for example, a light condensing layer such as an antireflection film or a microlens array, or a light diffusion layer that can scatter light reflected by the cathode and enter the power generation layer again may be provided. .

Various known antireflection layers can be provided as the antireflection layer. For example, when the transparent resin film is a biaxially stretched polyethylene terephthalate film, the refractive index of the easy adhesion layer adjacent to the film is 1.57. It is more preferable to set it to ˜1.63 because the transmittance can be improved by reducing the interface reflection between the film substrate and the easy adhesion layer. The method for adjusting the refractive index can be carried out by appropriately adjusting the ratio of the oxide sol having a relatively high refractive index such as tin oxide sol or cerium oxide sol and the binder resin. The easy adhesion layer may be a single layer, but may be composed of two or more layers in order to improve adhesion.

As the condensing layer, for example, it is processed so as to provide a structure on the microlens array on the sunlight receiving side of the support substrate, or the amount of light received from a specific direction is increased by combining with a so-called condensing sheet. Conversely, the incident angle dependency of sunlight can be reduced.

As an example of a microlens array, quadrangular pyramids having a side of 30 μm and an apex angle of 90 degrees are arranged two-dimensionally on the light extraction side of the substrate. One side is preferably 10 to 100 μm. If it is smaller than this, the effect of diffraction is generated and colored.

Also, examples of the light scattering layer include various antiglare layers, layers in which nanoparticles or nanowires such as metals or various inorganic oxides are dispersed in a colorless and transparent polymer, and the like.

[Patterning]
The method and process for patterning the electrode, the power generation layer, the hole transport layer, the electron transport layer, and the like according to the present invention are not particularly limited, and known methods can be appropriately applied.

If it is a soluble material such as a bulk heterojunction layer and a transport layer, only unnecessary portions may be wiped after the entire surface application such as die coating or dip coating, or directly at the time of application using a method such as an ink jet method or screen printing. Patterning may be performed.

In the case of an insoluble material such as an electrode material, the electrode can be patterned by a known method such as mask vapor deposition during vacuum deposition or etching or lift-off. Alternatively, the pattern may be formed by transferring a pattern formed on another substrate.

(Sealing)
Moreover, since the produced organic photoelectric conversion element 10 is not deteriorated by oxygen, moisture, or the like in the environment, it is preferable to seal not only the organic photoelectric conversion element but also an organic electroluminescence element by a known method. For example, a method of sealing a cap made of aluminum or glass by bonding with an adhesive, a plastic film on which a gas barrier layer such as aluminum, silicon oxide, or aluminum oxide is formed and the organic photoelectric conversion element top 10 are bonded with an adhesive. Method of bonding, spin coating of organic polymer materials with high gas barrier properties (polyvinyl alcohol, etc.), inorganic thin films with high gas barrier properties (silicon oxide, aluminum oxide, etc.) or organic films (parylene, etc.) deposited under vacuum And a method of laminating these in a composite manner.

(Optical sensor array)
Next, an optical sensor array to which the bulk heterojunction type organic photoelectric conversion element 10 described above is applied will be described in detail. The optical sensor array is produced by arranging the photoelectric conversion elements in a fine pixel form by utilizing the fact that the bulk heterojunction type organic photoelectric conversion elements generate a current upon receiving light, and projected onto the optical sensor array. A sensor having an effect of converting an image into an electrical signal.

FIG. 4 is a diagram showing the configuration of the optical sensor array. 4A is a top view, and FIG. 4B is a cross-sectional view taken along line A-A ′ of FIG. 4A.

In FIG. 4, an optical sensor array 20 is paired with an anode 22 as a lower electrode, a photoelectric conversion unit 24 for converting light energy into electrical energy, and an anode 22 on a substrate 21 as a holding member. The cathode 23 is sequentially laminated. The photoelectric conversion unit 24 includes two layers, a photoelectric conversion layer 24b having a bulk heterojunction layer in which a p-type semiconductor material and an n-type semiconductor material are uniformly mixed, and a buffer layer 24a. In the example shown in FIG. 4, six bulk heterojunction type organic photoelectric conversion elements are formed.

The substrate 21, the anode 22, the photoelectric conversion layer 24b, and the cathode 23 have the same configuration and role as the anode 12, the photoelectric conversion unit 14, and the cathode 13 in the bulk heterojunction photoelectric conversion element 10 described above.

For example, glass is used for the substrate 21, ITO is used for the anode 22, and aluminum is used for the cathode 23, for example. For example, the BP-1 precursor is used for the p-type semiconductor material of the photoelectric conversion layer 24b, and for example, the exemplified compound 13 is used for the n-type semiconductor material. The buffer layer 24a is made of PEDOT (poly-3,4-ethylenedioxythiophene) -PSS (polystyrene sulfonic acid) conductive polymer (trade name BaytronP, manufactured by Stark Vitec). Such an optical sensor array 20 was manufactured as follows.

An ITO film was formed on the glass substrate by sputtering and processed into a predetermined pattern shape by photolithography. The thickness of the glass substrate was 0.7 mm, the thickness of the ITO film was 200 nm, and the measurement area (light receiving area) of the ITO film after photolithography was 0.5 mm × 0.5 mm. Next, a PEDOT-PSS film was formed on the glass substrate 21 by spin coating (conditions: rotational speed = 1000 rpm, filter diameter = 1.2 μm). Thereafter, the substrate was heated in an oven at 140 ° C. for 10 minutes and dried. The thickness of the PEDOT-PSS film after drying was 30 nm.

Next, a 1: 1 mixed film of P3HT (poly-3hexylthiophene) and PCBM is formed on the PEDOT-PSS film by spin coating (conditions: rotational speed = 3300 rpm, filter diameter = 0.8 μm). did. In this spin coating, P3HT and PCBM were mixed with a chlorobenzene solvent in a ratio of 1: 1, and a mixture obtained by stirring (5 minutes) was used. After forming the mixed film of P3HT and PCBM, annealing was performed by heating in an oven at 180 ° C. for 30 minutes in a nitrogen gas atmosphere. The thickness of the mixed film of P3HT and PCBM after the annealing treatment was 70 nm.

Then, using a metal mask having a predetermined pattern opening, 5 nm of the compound 16 of the present invention is deposited as an electron transport layer on a mixed film of P3HT and PCBM, and then an aluminum layer as a cathode is formed by a deposition method ( (Thickness = 10 nm). Thereafter, 1 μm of PVA (polyvinyl alcohol) was formed by spin coating and baked at 150 ° C. to prepare a passivation layer (not shown). The optical sensor array 20 was produced as described above.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

Example 1 (use as a hole blocking layer)
<Preparation of Comparative Organic Photoelectric Conversion Element 1>
The transparent electrode patterned on the glass substrate was cleaned in the order of ultrasonic cleaning with surfactant and ultrapure water, followed by ultrasonic cleaning with ultrapure water, dried with nitrogen blow, and finally UV ozone cleaning. .

On this transparent substrate, Baytron P4083 (manufactured by Starck Vitec), which is a conductive polymer, was spin-coated with a film thickness of 30 nm, and then heat-dried at 140 ° C. for 10 minutes in the air.

After this, the substrate was brought into the glove box and worked in a nitrogen atmosphere. First, the substrate was heat-treated at 140 ° C. for 3 minutes in a nitrogen atmosphere. A solution was prepared by dissolving 1.5 mass% of plexcores OS2100 manufactured by Plextronics as a p-type semiconductor material and 1.5 mass% of E100 (PCBM) manufactured by Frontier Carbon as an n-type semiconductor material in chlorobenzene. While being filtered through a .45 μm filter, spin coating was performed at 500 rpm for 60 seconds, then at 2200 rpm for 1 second, and left at room temperature for 30 minutes.

Next, a solution in which batocuproine (BCP) manufactured by Aldrich was mixed with 2,2,3,3-tetrafluoro-1-propanol at a ratio of 0.5 mass% was spin-coated at 1500 rpm, and a hole block having a thickness of 10 nm was formed. A layer was formed.

Next, the substrate on which the series of organic layers was formed was placed in a vacuum deposition apparatus without being exposed to the atmosphere. The element was set so that the shadow mask with a width of 2 mm was orthogonal to the transparent electrode, and the inside of the vacuum deposition apparatus was depressurized to 10 ⁻³ Pa or less, and then 100 nm of Al was deposited. Finally, the heating for 30 minutes was performed at 120 degreeC, and the comparative organic photoelectric conversion element 1 was obtained. The vapor deposition rate was 2 nm / second, and the size was 2 mm square.

The obtained organic photoelectric conversion element 1 was sealed using an aluminum cap and a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) in a nitrogen atmosphere, and then taken out into the atmosphere.

<Production of Comparative Organic Photoelectric Conversion Element 2>
In the comparative organic photoelectric conversion element 1, instead of 0.5% 2,2,3,3-tetrafluoro-1-propanol solution of batocuproine as a hole blocking layer, Ti-isopropoxide was added to ethanol at 25 mmol / l. After the electrode portion was masked and spin-coated at 2000 rpm, it was taken out into the atmosphere and left for 60 minutes to hydrolyze Ti-isopropoxide, thereby obtaining a film thickness of 10 nm. A comparative organic photoelectric conversion element 2 was produced in the same manner except that a TiOx layer was formed and a hole blocking layer was formed.

<Preparation of organic photoelectric conversion elements 3 to 11 of the present invention>
In the comparative organic photoelectric conversion element 1, organic hole conversion layers 3 to 11 of the present invention were produced in the same manner except that the hole blocking layer was changed to the compound of the present invention described in Table 1 below instead of batocuproine. .

For the obtained organic photoelectric conversion elements 1 to 11, the following conversion efficiency and curve factor were evaluated, and durability was evaluated.

(Evaluation of conversion efficiency and fill factor)
Photoelectric conversion elements prepared above, was irradiated with light having an intensity of 100 mW / cm ² solar simulator (AM1.5G filter), a superposed mask in which the effective area 4.0 mm ² on the light receiving portion, the short circuit current density Jsc ( The four light-receiving portions formed on the same element were measured for mA / cm ² ), open-circuit voltage Voc (V), and fill factor (fill factor) FF, and the average value was obtained. Further, energy conversion efficiency η (%) was obtained from Jsc, Voc, and FF according to Equation 1.

Formula 1 Jsc (mA / cm ² ) × Voc (V) × FF = η (%)
(Durability evaluation 1)
A solar simulator (AM1.5G) was irradiated at an irradiation intensity of 100 mW / cm ² , voltage-current characteristics were measured, and initial conversion efficiency was measured. Further, assuming that the initial conversion efficiency at this time was 100, the conversion efficiency after 100 hours of irradiation with 100 mW / cm ² irradiation intensity with the resistance connected between the anode and the cathode was evaluated, and the relative reduction efficiency was calculated. .

Formula 2 Relative reduction efficiency (%) = (1−conversion efficiency after exposure / conversion efficiency before exposure) × 100
(Durability evaluation 2)
For the purpose of evaluating long-term storage stability, the conversion efficiency after storage for 300 hours under the condition of 65 degrees and 85% humidity was evaluated, and the relative reduction efficiency was calculated.

Formula 2 Relative reduction efficiency (%) = (conversion efficiency after 1-300 hours storage / conversion efficiency before storage) × 100

From Table 1, it can be seen that the use of the hole blocking layer of the present invention improves the fill factor and provides high conversion efficiency. Moreover, it turns out that the relative reduction efficiency which shows durability is also low and durability is high.

Example 2 (use as p-type semiconductor)
<Production of Comparative Organic Photoelectric Conversion Device 21>
As a comparative p-type semiconductor material, Comparative Compound 1 was synthesized with reference to Non-Patent Document 3. After the synthesis, reprecipitation with methanol: pure water = 10: 1 solution, followed by Soxhlet extraction in the order of acetone, hexane, dichloromethane, and chloroform, and again reconstitute the chloroform-dissolved components into methanol: pure water = 10: 1 solution. Purification was performed by precipitation. The number average molecular weight of Comparative Compound 1 was 37000.

Then, after the PEDOT: PSS layer was provided in the same manner as the organic photoelectric conversion element 1, the substrate was similarly brought into the glove box and operated in a nitrogen atmosphere. First, the substrate was heat-treated at 140 ° C. for 3 minutes in a nitrogen atmosphere. As a p-type semiconductor material in chlorobenzene, a liquid was prepared by dissolving 0.5% by mass of the comparative p-type semiconductor material 1 and 2.0% by mass of Frontier Carbon E100 (PCBM) as an n-type semiconductor material, While being filtered with a 0.45 μm filter, spin coating was performed at 2000 rpm for 60 seconds, followed by heating at 50 ° C. for 10 minutes, and then standing at room temperature for 12 hours.

Next, the substrate on which the series of organic layers was formed was placed in a vacuum deposition apparatus without being exposed to the atmosphere. The element was set so that the shadow mask with a width of 2 mm was orthogonal to the transparent electrode, and the inside of the vacuum deposition apparatus was depressurized to 10 ⁻³ Pa or less, and then 0.6 nm of lithium fluoride and 100 nm of Al were evaporated. Finally, the heating for 30 minutes was performed at 120 degreeC, and the comparative organic photoelectric conversion element 21 was obtained. The vapor deposition rate was 2 nm / second, and the size was 2 mm square.

The obtained organic photoelectric conversion element 21 was sealed using an aluminum cap and a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) in a nitrogen atmosphere, and then taken out into the atmosphere. The following conversion efficiency and open circuit voltage were evaluated.

<Preparation of the organic photoelectric conversion elements 22 to 26 of the present invention>
In the comparative organic photoelectric conversion element 21, the p-type semiconductor material was replaced with the compound of the present invention described in Table 2 below in place of the comparative compound 1, which was the comparative p-type semiconductor material. After producing the organic photoelectric conversion elements 22 to 24 of the invention, the conversion efficiency and the open circuit voltage were similarly evaluated. In the case where the p-type semiconductor material is a polymer, purification is performed by the same reprecipitation and Soxhlet extraction method as in the comparative p-type semiconductor material 1, and in the case of a low molecular material, silica gel column chromatography and gel permeation chromatography are performed. Purification was performed using The number average molecular weights of the exemplary compounds 102 and 104 used in the organic

photoelectric conversion elements

22, 23, and 26 were 7000 to 8000.

Furthermore, after forming a bulk heterojunction layer similarly to the organic

photoelectric conversion elements

24 and 23 as the organic photoelectric conversion elements 25 and 26 of this invention, the said exemplary compounds 16 and 44 are made into 2 in the ratio of 0.5 mass%. A solution mixed with 2,3,3-tetrafluoro-1-propanol was spin-coated at 1500 rpm to form a 10 nm-thick hole blocking layer. Thereafter, the organic photoelectric conversion elements 25 and 26 were produced in the same manner as the organic photoelectric conversion element 23, and the conversion efficiency was evaluated in the same manner as in Example 1.

From Table 2, it is clear that high open-circuit voltage and photoelectric conversion efficiency can be obtained by using the p-type semiconductor material of the present invention. It can also be seen that higher photoelectric conversion efficiency can be obtained by providing a hole blocking layer made of the material of the present invention.

DESCRIPTION OF SYMBOLS 10 Bulk heterojunction type organic photoelectric conversion element 11 Substrate 12 Anode 13 Cathode 14 Photoelectric conversion part (bulk heterojunction layer)
14p p layer 14i i layer 14n n layer 14 'first photoelectric conversion part 15 charge recombination layer 16 second photoelectric conversion part 17 hole transport layer 18 electron transport layer 20 photosensor array 21 substrate 22 anode 23 cathode 24 photoelectric Conversion part 24a Hole transport layer 24b Photoelectric conversion layer

Claims

An organic photoelectric conversion element having a cathode, an anode, and a bulk heterojunction layer in which a p-type semiconductor material and an n-type semiconductor material are mixed, and is represented by at least the following general formula (1) between the cathode and the anode. An organic photoelectric conversion device comprising a layer containing a compound having a partial structure.

(In the formula, Z 1 represents a substituted or unsubstituted nitrogen-containing aromatic 6-membered ring, Z 2 represents a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring. R 1 represents a hydrogen atom, halogen, This represents a substituent selected from an atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group.
2. The organic photoelectric device according to claim 1, wherein a layer containing a compound having a partial structure represented by the general formula (1) is present between the bulk heterojunction layer and the cathode. Conversion element.
The organic photoelectric conversion device according to claim 1, wherein the layer containing the compound having a partial structure represented by the general formula (1) is a bulk heterojunction layer.
The organic photoelectric conversion device according to any one of claims 1 to 3, comprising a compound having two or more partial structures represented by the general formula (1) in a molecule. .
The compound having a partial structure represented by the general formula (1) is a compound having a partial structure represented by the following general formula (2a) or (2b): The organic photoelectric conversion element of Claim 1.

(Wherein X 1 to X 4 represent a substituted or unsubstituted carbon atom or a nitrogen atom. Z 3 represents a substituted or unsubstituted aromatic hydrocarbon ring or aromatic heterocyclic ring. R 2 represents a hydrogen atom, It represents a substituent selected from a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group.)
6. The organic photoelectric device according to claim 1, wherein the aromatic heterocycle represented by Z 2 in the general formula (1) is a nitrogen-containing aromatic 6-membered ring. Conversion element.
7. The compound having a partial structure represented by the general formula (1) is a compound having a partial structure represented by the following general formula (3a) or (3b): The organic photoelectric conversion element of Claim 1.

(Wherein R 3 represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, or a heteroaryl group. X 5 to X 8 are substituted or unsubstituted. Represents a carbon atom or a nitrogen atom.)
8. The compound according to claim 1, wherein the compound having a partial structure represented by the general formula (1) is a compound having a partial structure represented by the following general formula (4). The organic photoelectric conversion element as described.

(Wherein R 4 to R 10 represent a substituent selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group.)
9. The compound according to claim 1, wherein the compound having a partial structure represented by the general formula (1) is a compound having a partial structure represented by the following general formula (5). The organic photoelectric conversion element as described.

(Wherein R 11 to R 13 represent a substituent selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group. Z 4 represents a substituted or unsubstituted group. A nitrogen-containing aromatic ring, Z 5 represents a substituted or unsubstituted aromatic ring and a heteroaromatic ring, p represents an integer of 0 to 4 and q represents an integer of 2 to 6)
The compound having a partial structure represented by the general formula (1), (2a), (2b), (3a), (3b), (4) or (5) is a low molecular weight compound having a molecular weight of less than 5000. The organic photoelectric conversion device according to any one of claims 1 to 9, wherein
11. The compound according to claim 1, wherein the compound having a partial structure represented by the general formula (1) is a compound having a partial structure represented by the following general formula (6). The organic photoelectric conversion element as described.

(Wherein R 14 to R 16 represent a substituent selected from a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a cycloalkyl group, an aryl group, and a heteroaryl group. Z 6 represents a substituted or unsubstituted group. A nitrogen-containing aromatic ring, Z 7 represents a substituted or unsubstituted aromatic ring and a heteroaromatic ring, r represents an integer of 0 to 4, and s represents an integer of 2 to 10,000)
The organic photoelectric conversion device according to claim 11, wherein the compound having a partial structure represented by the general formula (6) is a polymer compound having a molecular weight of 5000 or more.
A layer containing a compound having a partial structure represented by the general formula (1), (2a), (2b), (3a), (3b), (4), (5), or (6), The organic photoelectric conversion device according to any one of claims 1 to 12, wherein the organic photoelectric conversion device is produced by a solution coating method.
A solar cell using the organic photoelectric conversion device according to any one of claims 1 to 13.
An optical sensor array comprising the organic photoelectric conversion elements according to any one of claims 1 to 13 arranged in an array.