WO2013102985A1

WO2013102985A1 - Organic photoelectric conversion element and organic thin-film solar battery module

Info

Publication number: WO2013102985A1
Application number: PCT/JP2012/008316
Authority: WO
Inventors: 竜志前田; 圭一安川; 東海林　弘
Original assignee: 出光興産株式会社
Priority date: 2012-01-06
Filing date: 2012-12-26
Publication date: 2013-07-11
Also published as: TW201341345A; JPWO2013102985A1

Abstract

Disclosed is an organic photoelectric conversion element comprising: a pair of electrodes comprising a positive electrode and negative electrode; an intermediate electrode arranged between said pair of electrodes; a first organic photoelectric conversion layer arranged between said positive electrode and intermediate electrode; a second organic photoelectric conversion layer arranged between said negative electrode and intermediate electrode; and a doping layer including an acceptor material and a donor material between said intermediate electrode and second organic photoelectric conversion layer; wherein the energy Ip (D) of the ionisation potential (Ip) of said donor material and the absolute value |LUMO(A)| of the energy level of the lowest unoccupied molecular orbital (LUMO) of said acceptor material is in the relationship: Ip(D)-|LUMO(A)|≦ 0.7eV, and the Ip(D)of said donor material is at least 5.4 eV but no more than 5.6 eV.

Description

Organic photoelectric conversion element and organic thin film solar cell module

The present invention relates to an organic photoelectric conversion element and an organic thin film solar cell module that generate electricity by receiving light. In more detail, it is related with the organic photoelectric conversion element which is an organic thin film solar cell, and the organic thin film solar cell module using the said organic photoelectric conversion element.

Solar cells have attracted much attention as a clean energy source in recent years against the background of fossil fuel depletion problems and global warming problems, and research and development have been actively conducted.
Conventionally, silicon solar cells represented by single crystal Si, polycrystal Si, amorphous Si, etc. have been put into practical use. However, as the cost and raw material Si shortage problems surface, The demand for next generation solar cells is increasing. Against this background, organic solar cells are attracting much attention as next-generation solar cells next to silicon-based solar cells because they are inexpensive, have low toxicity, and do not have a fear of shortage of raw materials.

An organic solar cell is a device that exhibits an electrical output with respect to an optical input, as represented by a photodiode and an imaging device that convert an optical signal into an electrical signal, and a solar cell that converts optical energy into electrical energy.
However, organic solar cells have a problem of low energy conversion efficiency compared to silicon-based solar cells (single crystal silicon, polycrystalline silicon, amorphous silicon) currently used, and have been put into practical use. Not in.

As a means for improving the conversion efficiency of an organic solar cell, a tandem type element in which elements are stacked has been reported. A tandem element is a structure in which a plurality of heterojunction semiconductors are stacked to form one element with an intermediate electrode serving as a connection layer sandwiched between the semiconductors. The tandem type device has an open-ended voltage when there is no electrical or optical loss in the intermediate electrode as a connection layer, compared to a single layer type device (single device; device having only one heterojunction semiconductor). Can be doubled (in the case of two layers).

Regarding the tandem type element, Patent Document 1 uses a metal cluster as an intermediate electrode, thins the film thickness of the front cell and the back cell to balance light absorption, and generates a photocurrent generated in the front cell and the back cell. An example of succeeding in improving the conversion efficiency as compared with a single-layer type element by making it substantially the same will be disclosed.
Non-Patent Document 1 discloses that the conversion efficiency of a tandem organic solar cell using a 4MeO-TPD layer doped with F4-TCNQ as a charge transport layer and a layer adjacent to the intermediate electrode is higher than that of a single-type device. Reporting improvements.

JP-T-2004-523129

An object of the present invention is to provide a photoelectric conversion element having high conversion efficiency.

As a result of intensive studies, the present inventors have found that the donor material constituting the doped layer has a low ionization potential (Ip), such as ZnPc (5.1 eV) or 4MeO-TPD (5.3 eV), where Ip ≦ 5.3 eV. It has been found that the use of a donor material has a drawback that the efficiency of organic solar power cannot be increased.
Based on the above findings, the present inventors can obtain a high effect even when the ionization potential (Ip) of the donor material is large in the case where the donor material constituting the doped layer satisfies the requirements having an energy level relationship. I found out.

According to the present invention, the following photoelectric conversion elements and the like are provided.
1. A pair of electrodes consisting of a positive electrode and a negative electrode;
An intermediate electrode disposed between the pair of electrodes;
A first organic photoelectric conversion layer disposed between the positive electrode and the intermediate electrode;
A second organic photoelectric conversion layer disposed between the negative electrode and the intermediate electrode;
An organic photoelectric conversion device comprising a doped layer including an acceptor material and a donor material between the intermediate electrode and the second organic photoelectric conversion layer,
The energy Ip (D) of the ionization potential (Ip) of the donor material and the absolute value | LUMO (A) | of the lowest unoccupied molecular orbital (LUMO) of the acceptor material are Ip (D) − | LUMO ( A) | ≦ 0.7 eV,
The organic photoelectric conversion element whose Ip (D) of the said donor material is 5.4 eV or more and 5.6 eV or less.
2. 2. The organic photoelectric conversion element according to 1, wherein the acceptor material is a cyano compound.
3. 3. The organic photoelectric conversion element according to 1 or 2, wherein the acceptor material is a tetracyanoquinodimethane derivative represented by the following formula (1).

(In the formula, each R is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, a dialkylamine group having 2 to 20 carbon atoms, or a cyano group. .)
4). 4. The organic photoelectric conversion device according to 3, wherein at least one of the four Rs of the tetracyanoquinodimethane derivative represented by the formula (1) is a cyano group.
5. 5. The organic photoelectric conversion device according to any one of 1 to 4, wherein the donor material is a compound represented by the following formula (2) or formula (3).

(Wherein X ¹ , X ² , Y ¹ and Y ² are each independently a substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms.
R ¹ and R ² are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 ring carbon atoms, A substituted or unsubstituted alkenyl group having 2 to 40 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 40 carbon atoms, a substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms, and 6 to 40 ring atoms A substituted or unsubstituted heteroaryl group, a substituted or unsubstituted alkoxy group having 1 to 40 carbon atoms, a substituted or unsubstituted cycloalkoxy group having 3 to 10 ring carbon atoms, a substituted or unsubstituted 6 to 40 ring carbon atoms, or Unsubstituted aryloxy group, substituted or unsubstituted arylamino group having 6 to 40 ring carbon atoms, or substituted or unsubstituted alkylamino group having 1 to 40 carbon atoms It is. )
6). 6. The organic photoelectric conversion device according to 5, wherein the substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms of X ¹ , X ² , Y ¹ and Y ² is a group represented by the following formula (4).

Wherein R ³ to R ⁷ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 3 to 10 ring carbon atoms. Group, substituted or unsubstituted alkenyl group having 2 to 40 carbon atoms, substituted or unsubstituted alkynyl group having 2 to 40 carbon atoms, substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms, number of ring forming atoms A substituted or unsubstituted heteroaryl group having 6 to 40 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 40 carbon atoms, a substituted or unsubstituted cycloalkoxy group having 3 to 10 ring carbon atoms, and 6 to 6 carbon atoms forming a ring 40 substituted or unsubstituted aryloxy groups, substituted or unsubstituted arylamino groups having 6 to 40 ring carbon atoms, or substituted or unsubstituted alkyl groups having 1 to 40 carbon atoms It is an amino group.)
7). 5. The organic photoelectric conversion device according to any one of 1 to 4, wherein the donor material is an aromatic amine derivative represented by the following formula (5).

(In the formula, L is a phenylene group, a biphenylene group, a terphenylene group, or a fluorenylene group having a C 1-6 alkyl group which may form a ring at the 9-position as a substituent.
Ar ¹ is a phenyl group substituted with an aryl group selected from a phenyl group, a naphthyl group, and a phenanthryl group, or a naphthyl group,
Ar ² to Ar ⁴ are each independently a phenyl group, a phenyl group substituted with a naphthyl group, a biphenyl group, a terphenyl group, a naphthyl group, a naphthyl group substituted with a phenyl group, an anthranyl group, a phenanthryl group, a pyrenyl group, a chrysenyl group, A fluoranthenyl group or a fluorenyl group having a C 1-6 alkyl group which may form a ring at the 9-position as a substituent;
Ar ¹ to Ar ⁴ are different from each other, or any three of Ar ¹ to Ar ⁴ are different from each other.
However, Ar ¹ to Ar ⁴ may be further substituted with an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 1 to 10 carbon atoms, or a halogen atom. )
8). 5. The organic photoelectric conversion device according to any one of 1 to 4, wherein the donor material is an aromatic amine derivative represented by the following formula (5 ′).

Wherein L ₁ to L ₃ are each independently a phenylene group, a biphenylene group, a terphenylene group, or a fluorenylene having an alkyl group having 1 to 6 carbon atoms which may form a ring at the 9-position as a substituent. It is a group.
Ar ¹ to Ar ⁶ are each independently a phenyl group, a phenyl group substituted with a naphthyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenyl group-substituted naphthyl group, an anthranyl group, a phenanthryl group, a pyrenyl group, a chrysenyl group, A fluoranthenyl group or a fluorenyl group having a C 1-6 alkyl group which may form a ring at the 9-position as a substituent.
However, Ar ¹ to Ar ⁶ may be further substituted with an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 1 to 10 carbon atoms, or a halogen atom. )
9. A pair of electrodes consisting of a positive electrode and a negative electrode;
An intermediate electrode disposed between the pair of electrodes;
A first organic photoelectric conversion layer disposed between the positive electrode and the intermediate electrode;
A second organic photoelectric conversion layer disposed between the negative electrode and the intermediate electrode;
An acceptor material that is a tetracyanoquinodimethane derivative represented by the following formula (1) and a compound represented by the following formula (2) or (3) between the intermediate electrode and the second organic photoelectric conversion layer. An organic photoelectric conversion element comprising a doped layer containing a donor material,
The energy Ip (D) of the ionization potential (Ip) of the donor material and the absolute value | LUMO (A) | of the lowest unoccupied molecular orbital (LUMO) of the acceptor material are Ip (D) − | LUMO ( A) | ≦ 0.7 eV,
The organic photoelectric conversion element whose Ip (D) of the said donor material is 5.4 eV or more and 5.6 eV or less.

(In the formula, each R is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, a dialkylamine group having 2 to 20 carbon atoms, or a cyano group. .)

(Wherein X ¹ , X ² , Y ¹ and Y ² are each independently a substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms.
R ¹ and R ² are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 ring carbon atoms, A substituted or unsubstituted alkenyl group having 2 to 40 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 40 carbon atoms, a substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms, and 6 to 40 ring atoms A substituted or unsubstituted heteroaryl group, a substituted or unsubstituted alkoxy group having 1 to 40 carbon atoms, a substituted or unsubstituted cycloalkoxy group having 3 to 10 ring carbon atoms, a substituted or unsubstituted 6 to 40 ring carbon atoms, or Unsubstituted aryloxy group, substituted or unsubstituted arylamino group having 6 to 40 ring carbon atoms, or substituted or unsubstituted alkylamino group having 1 to 40 carbon atoms It is. )
10. 10. The organic photoelectric conversion element according to 9, wherein at least one of four Rs of the tetracyanoquinodimethane derivative represented by the formula (1) is a cyano group.
11. The organic photoelectric conversion device according to 9 or 10, wherein the substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms of X ¹ , X ² , Y ¹ and Y ² is a group represented by the following formula (4): .

Wherein R ³ to R ⁷ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 3 to 10 ring carbon atoms. Group, substituted or unsubstituted alkenyl group having 2 to 40 carbon atoms, substituted or unsubstituted alkynyl group having 2 to 40 carbon atoms, substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms, number of ring forming atoms A substituted or unsubstituted heteroaryl group having 6 to 40 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 40 carbon atoms, a substituted or unsubstituted cycloalkoxy group having 3 to 10 ring carbon atoms, and 6 to 6 carbon atoms forming a ring 40 substituted or unsubstituted aryloxy groups, substituted or unsubstituted arylamino groups having 6 to 40 ring carbon atoms, or substituted or unsubstituted alkyl groups having 1 to 40 carbon atoms It is an amino group.)
12 A pair of electrodes consisting of a positive electrode and a negative electrode;
An intermediate electrode disposed between the pair of electrodes;
A first organic photoelectric conversion layer disposed between the positive electrode and the intermediate electrode;
A second organic photoelectric conversion layer disposed between the negative electrode and the intermediate electrode;
An acceptor material that is a tetracyanoquinodimethane derivative represented by the following formula (1) and a donor that is an aromatic amine derivative represented by the following formula (5) between the intermediate electrode and the second organic photoelectric conversion layer. An organic photoelectric conversion element comprising a doped layer containing a material,
The energy Ip (D) of the ionization potential (Ip) of the donor material and the absolute value | LUMO (A) | of the lowest unoccupied molecular orbital (LUMO) of the acceptor material are Ip (D) − | LUMO ( A) | ≦ 0.7 eV,
The organic photoelectric conversion element whose Ip (D) of the said donor material is 5.4 eV or more and 5.6 eV or less.

(In the formula, L is a phenylene group, a biphenylene group, a terphenylene group, or a fluorenylene group having a C 1-6 alkyl group which may form a ring at the 9-position as a substituent.
Ar ¹ is a phenyl group substituted with an aryl group selected from a phenyl group, a naphthyl group, and a phenanthryl group, or a naphthyl group,
Ar ² to Ar ⁴ are each independently a phenyl group, a phenyl group substituted with a naphthyl group, a biphenyl group, a terphenyl group, a naphthyl group, a naphthyl group substituted with a phenyl group, an anthranyl group, a phenanthryl group, a pyrenyl group, a chrysenyl group, A fluoranthenyl group or a fluorenyl group having a C 1-6 alkyl group which may form a ring at the 9-position as a substituent;
Ar ¹ ~ Ar ⁴ are different from each other, or one of ^Ar 1 ~ Ar ⁴ ^is any one of the same of Ar 1 ~ Ar ^4.
However, Ar ¹ to Ar ⁴ may be further substituted with an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 1 to 10 carbon atoms, or a halogen atom. )
13. 13. The organic photoelectric conversion element according to 12, wherein at least one of four Rs of the tetracyanoquinodimethane derivative represented by the formula (1) is a cyano group.
14 A pair of electrodes consisting of a positive electrode and a negative electrode;
An intermediate electrode disposed between the pair of electrodes;
A first organic photoelectric conversion layer disposed between the positive electrode and the intermediate electrode;
A second organic photoelectric conversion layer disposed between the negative electrode and the intermediate electrode;
An acceptor material that is a tetracyanoquinodimethane derivative represented by the following formula (1) and an aromatic amine derivative represented by the following formula (5 ′) between the intermediate electrode and the second organic photoelectric conversion layer. An organic photoelectric conversion element comprising a doped layer containing a donor material,
The energy Ip (D) of the ionization potential (Ip) of the donor material and the absolute value | LUMO (A) | of the lowest unoccupied molecular orbital (LUMO) of the acceptor material are Ip (D) − | LUMO ( A) | ≦ 0.7 eV,
The organic photoelectric conversion element whose Ip (D) of the said donor material is 5.4 eV or more and 5.6 eV or less.

Wherein L ₁ to L ₃ are each independently a phenylene group, a biphenylene group, a terphenylene group, or a fluorenylene having a C 1-6 alkyl group which may form a ring at the 9-position as a substituent. It is a group.
Ar ¹ to Ar ⁶ are each independently a phenyl group, a phenyl group substituted with a naphthyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenyl group-substituted naphthyl group, an anthranyl group, a phenanthryl group, a pyrenyl group, a chrysenyl group, A fluoranthenyl group or a fluorenyl group having a C 1-6 alkyl group which may form a ring at the 9-position as a substituent.
However, Ar ¹ to Ar ⁶ may be further substituted with an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 1 to 10 carbon atoms, or a halogen atom. )
15. 15. The organic photoelectric conversion element according to 1 to 14, wherein the second organic photoelectric conversion layer contains a donor material for the doped layer.
16. 16. The organic photoelectric conversion element according to 15, wherein the second organic photoelectric conversion layer includes a hole transport layer in contact with the doped layer, and the hole transport layer includes a donor material of the doped layer.
17. The intermediate electrode is made of 1 to 16 selected from Pt and Au, and one or more selected from metals and oxides of Ni, Cu, Zn, Pd, Ag, Cd, Mo, V, Ti, In, Sn, and Ca. The organic photoelectric conversion element in any one.
18. 18. An organic thin film solar cell module using the organic photoelectric conversion device as described in any one of 1 to 17 above.

According to the present invention, a photoelectric conversion element having high conversion efficiency can be provided.

It is a figure which shows the approximated curve obtained from the literature value and calculation value of HOMO of a literature description compound, and LUMO. It is a figure which shows the JV characteristic of the doped layer single layer element of Evaluation Examples 1 and 3. It is a figure which shows the JV characteristic of the doped layer single layer element of the evaluation examples 2 and 4.

The photoelectric conversion element of the present invention includes a pair of electrodes composed of a positive electrode and a negative electrode, an intermediate electrode disposed between the pair of electrodes, a first organic photoelectric conversion layer disposed between the positive electrode and the intermediate electrode, A second organic photoelectric conversion layer disposed between the negative electrode and the intermediate electrode, and a doped layer including an acceptor material and a donor material are provided between the intermediate electrode and the second organic photoelectric conversion layer.
Hereinafter, each layer will be described.

[Dope layer]
The doped layer of the organic photoelectric conversion element of the present invention includes an acceptor material and a donor material, and Ip (D) that is the ionization potential (Ip) energy of the donor material and the energy of the lowest unoccupied molecular orbital (LUMO) of the acceptor material. | LUMO (A) |, which is the absolute value of the level, has a relationship of Ip (D) − | LUMO (A) | ≦ 0.7 eV, preferably Ip (D) − | LUMO (A) | ≦ 0. 6 eV.
The lower limit of Ip (D) − | LUMO (A) | is not particularly limited, but is 0 eV, for example.
The donor material of the doped layer has an Ip (D) of 5.4 eV or more and 5.6 eV or less, preferably 5.4 eV or more and 5.5 eV or less.

The doped layer is a low-resistance and high-transmittance layer, and can function as an optical spacer layer that does not interfere with charge transport between adjacent photoelectric conversion layers by satisfying the above energy level requirements. By providing the doped layer, it is possible to design an optimal element thickness considering the optical interference effect caused by incident light and reflected light, and to improve the photoelectric conversion characteristics of the organic photoelectric conversion element.
The above effect is significant when the photoelectric conversion element is a tandem element having two or more photoelectric conversion layers.

Ip (D), which is the ionization potential energy of the donor material, and | LUMO (A) |, which is the absolute value of the LUMO energy level of the acceptor material, can be measured, for example, by the following method.
Ip (D), which is the ionization potential energy of the donor material, forms a thin film of the target compound on the ITO glass substrate by vacuum deposition, and uses the thin film on the ITO glass substrate to produce a photoelectron spectrometer (RIKEN Keiki Co., Ltd.) in the atmosphere. It can be measured using Co., Ltd. (AC-3). Specifically, it can be measured by irradiating a thin film of the target compound with light and measuring the amount of electrons generated by charge separation at that time.

The acceptor material of the doped layer of the photoelectric conversion element of the present invention may have a deep HOMO value, and the photoelectron spectrometer may not be able to accurately measure the HOMO value. Since LUMO is a value calculated from the difference between the HOMO value and the energy gap obtained from the optical absorption edge, the LUMO of the acceptor material may also be difficult to accurately measure.
For acceptor materials having a deep HOMO value, the LUMO value can be calculated by using molecular orbital software.

For example, when WINWOSTER is used as molecular orbital software, “J. AM. CHEM. SOC. 2007, 129, 15259”, “Adv. Mater. 2005, 17, 285.”, “Appl. Phys. Lett., 2001” 79, 126. ”and“ J. Appl. Phys., 2003, 93, 3693. ”, the literature values of these compounds (values described in the above literature) and molecular orbital software are used. The calculated values (calculation conditions are MOPAC / AM1) are compared. These compounds are compounds commonly used in organic thin-film solar cells, and have high ionization potential and affinity.
The compounds described in the literature are shown below. Table 1 shows literature values and calculated values of HOMO and LUMO of the compounds described in the literature. The literature value and the calculated value are different from each other because the literature value is a value as a physical property of the material thin film as a solid, whereas the calculated value is a value obtained by calculation based on one molecule. .

As shown in FIG. 1, by calculating an approximate curve from the above literature values and calculated values, and applying the calculated value of the target compound to the approximate curve, HOMO and LUMO of the target compound can be calculated.
Example HOMO and LUMO in the case of using the approximate curve of FIG. 1 HOMO and LUMO of Compound C and D are 7.9 eV and LUMO of 4.6 eV for Compound C, and HOMO of Compound D is 7.1 eV and LUMO is 4.9 eV.

The acceptor material is, for example, an organic compound having an electron-withdrawing substituent, and specifically, a quinoid derivative having an electron-withdrawing substituent, a pyrazine derivative having an electron-withdrawing substituent, and an electron-withdrawing substitution. And arylborane derivatives having a group, imide derivatives having an electron-withdrawing substituent, and the like.
For example, examples of the quinoid derivative include quinodimethane derivatives, thiopyran dioxide derivatives, thioxanthene dioxide derivatives, quinone derivatives, and the like, and examples of electron-withdrawing substituents include fluoro groups and cyano groups. The species can be used alone or as a mixture of two or more species.
Of these, preferred are cyano compounds in which the substituent of the electron-withdrawing group is a cyano group.

The cyano compound that is an acceptor material is preferably a tetracyanoquinodimethane derivative represented by the following formula (1). In the tetracyanoquinodimethane derivative represented by the formula (1), at least one of the four Rs is preferably a cyano group, and more preferably at least two of the four Rs are cyano groups.

As the donor material, for example, in the case of an organic compound, N, N′-bis (3-tolyl) -N, N′-diphenylbenzidine (mTPD), N, N′-dinaphthyl-N, N′-diphenylbenzidine ( NPD), 4,4 ′, 4 ″ -tris (phenyl-3-tolylamino) triphenylamine (MTDATA) and other amine compounds; phthalocyanine (Pc), copper phthalocyanine (CuPc), zinc phthalocyanine (ZnPc) Phthalocyanines such as titanyl phthalocyanine (TiOPc); porphyrins typified by octaethylporphyrin (OEP), platinum octaethylporphyrin (PtOEP), zinc tetraphenylporphyrin (ZnTPP), and the like; acenes such as anthracene, tetracene, and pentacene And a thiophene group etc. In the case of a high molecular compound, main chain conjugated polymers such as polyhexylthiophene (P3HT) and methoxyethylhexyloxyphenylene vinylene (MEHPPV), and side chains represented by polyvinylcarbazole and the like. Type polymers.
These compounds can be used individually by 1 type or in mixture of 2 or more types.

The donor material is preferably a compound represented by the following formula (2) or formula (3).

(Wherein X ¹ , X ² , Y ¹ and Y ² are each independently a substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms.
R ¹ and R ² are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 ring carbon atoms, A substituted or unsubstituted alkenyl group having 2 to 40 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 40 carbon atoms, a substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms, and 6 to 40 ring atoms A substituted or unsubstituted heteroaryl group, a substituted or unsubstituted alkoxy group having 1 to 40 carbon atoms, a substituted or unsubstituted cycloalkoxy group having 3 to 10 ring carbon atoms, a substituted or unsubstituted 6 to 40 ring carbon atoms, or Unsubstituted aryloxy group, substituted or unsubstituted arylamino group having 6 to 40 ring carbon atoms, or substituted or unsubstituted alkylamino group having 1 to 40 carbon atoms It is. )

In the above formulas (2) and (3), the substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms of X ¹ , X ² , Y ¹ and Y ² is preferably represented by the following formula (4) It is a group.

Wherein R ³ to R ⁷ are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 3 to 10 ring carbon atoms. Group, substituted or unsubstituted alkenyl group having 2 to 40 carbon atoms, substituted or unsubstituted alkynyl group having 2 to 40 carbon atoms, substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms, number of ring forming atoms A substituted or unsubstituted heteroaryl group having 6 to 40 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 40 carbon atoms, a substituted or unsubstituted cycloalkoxy group having 3 to 10 ring carbon atoms, and 6 to 6 carbon atoms forming a ring 40 substituted or unsubstituted aryloxy groups, substituted or unsubstituted arylamino groups having 6 to 40 ring carbon atoms, or substituted or unsubstituted alkyl groups having 1 to 40 carbon atoms It is an amino group.)

Below, the preferable specific example of a compound shown by Formula (2) and (3) is shown. However, the compounds represented by (2) and (3) are not limited to the following.

Of the specific examples of the compounds represented by the above formulas (2) and (3), the following compounds are more preferable.

The donor material is preferably an aromatic amine derivative represented by the following formula (5) or (5 ′).

(In Formula (5), L is a phenylene group, a biphenylene group, a terphenylene group, or a fluorenylene group having a C 1-6 alkyl group which may form a ring at the 9-position as a substituent.
Ar ¹ is a phenyl group substituted with an aryl group selected from a phenyl group, a naphthyl group, and a phenanthryl group, or a naphthyl group,
Ar ² to Ar ⁴ are each independently a phenyl group, a phenyl group substituted with a naphthyl group, a biphenyl group, a terphenyl group, a naphthyl group, a naphthyl group substituted with a phenyl group, an anthranyl group, a phenanthryl group, a pyrenyl group, a chrysenyl group, A fluoranthenyl group or a fluorenyl group having a C 1-6 alkyl group which may form a ring at the 9-position as a substituent;
Ar ¹ to Ar ⁴ are different from each other, or any three of Ar ¹ to Ar ⁴ are different from each other.
However, Ar ¹ to Ar ⁴ may be further substituted with an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 1 to 10 carbon atoms, or a halogen atom. )
(In Formula (5 ′), L ₁ to L ₃ are each independently a phenylene group, a biphenylene group, a terphenylene group, or an alkyl group having 1 to 6 carbon atoms that may form a ring at the 9-position as a substituent. It is a fluorenylene group having a group.
Ar ¹ to Ar ⁶ are each independently a phenyl group, a phenyl group substituted with a naphthyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenyl group-substituted naphthyl group, an anthranyl group, a phenanthryl group, a pyrenyl group, a chrysenyl group, A fluoranthenyl group or a fluorenyl group having a C 1-6 alkyl group which may form a ring at the 9-position as a substituent.
However, Ar ¹ to Ar ⁶ may be further substituted with an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 1 to 10 carbon atoms, or a halogen atom. )

As described above, at least three of Ar ¹ to Ar ^{4 in} the formula (5) are a substituent (an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an alkoxycarbonyl having 1 to 10 carbon atoms). The aryl skeleton portions excluding the group or halogen atom are different from each other.

Specific examples of the compound represented by the formula (5) or (5 ′) are shown below. However, the compound represented by the formula (5) or (5 ′) is not limited to the following compounds.

Preferably, the doped layer is a tetracyanoquinodimethane derivative in which the acceptor material is represented by the formula (1), and the donor material is a combination of compounds represented by the formula (2) or (3), or the acceptor The material is a tetracyanoquinodimethane derivative represented by the formula (1), and the donor material is a doped layer made of a combination of aromatic amine derivatives represented by the formula (5) or (5 ′).

In the doped layer, the content ratio (or doping ratio) of the acceptor material and the donor material is, for example, 0.1 to 80%, preferably 0.5 to 50% of the acceptor material with respect to the donor material in terms of mass ratio. More preferably, it is 1 to 20%.
Further, the thickness of the doped layer is, for example, 1 to 300 nm, preferably 5 to 250 nm, and more preferably 10 to 200 nm.

[First organic photoelectric conversion layer and second organic photoelectric conversion layer]
Each of the first organic photoelectric conversion layer and the second organic photoelectric conversion layer can have the following layer structure. The layer configurations of the first organic photoelectric conversion layer and the second organic photoelectric conversion layer may be the same as or different from each other.
(1) Lower electrode (positive electrode) | Charge transport layer / i layer (mixed layer of p and n materials) | Upper electrode (negative electrode)
(2) Lower electrode (positive electrode) | i layer / charge transport layer | Upper electrode (negative electrode)
(3) Lower electrode (positive electrode) | Charge transport layer / i layer / charge transport layer | Upper electrode (negative electrode)
(4) Lower electrode (positive electrode) | Charge transport layer / p layer / n layer | Upper electrode (negative electrode)
(5) Lower electrode (positive electrode) | p layer / n layer / charge transport layer | Upper electrode (negative electrode)
(6) Lower electrode (positive electrode) | Charge transport layer / p layer / n layer / charge transport layer | Upper electrode (negative electrode)
(7) Lower electrode (positive electrode) | Charge transport layer / p layer / n layer / buffer layer | Upper electrode (negative electrode)
(8) Lower electrode (positive electrode) | Buffer layer / charge transport layer / p layer / n layer / buffer layer | Upper electrode (negative electrode)
(9) Lower electrode (positive electrode) | Buffer layer / charge transport layer / p layer / i layer / n layer / buffer layer | Upper electrode (negative electrode)

In the above configuration, the p layer and the n layer may be replaced (reverse configuration). For example, when the above (4) and (6) are reversed, the following structures are mentioned. In this case, the lower electrode that was the positive electrode is used as the negative electrode, and the upper electrode is used as the positive electrode.
(10) Lower electrode (negative electrode) | Charge transport layer / n layer / p layer | Upper electrode (positive electrode)
(11) Lower electrode (negative electrode) | Charge transport layer / n layer / p layer / charge transport layer | Upper electrode (positive electrode)

The charge transport layer is a layer that transports charges. For example, in the case of (6), the charge transport layer on the positive electrode side is a hole transport layer, and the charge transport layer on the negative electrode side is an electron transport layer. .
The charge transport layer preferably has a function of blocking charge transport opposite to the main transport charge. Specifically, in order to efficiently move holes generated in the charge generation layer (eg, p layer and n layer) to the positive electrode, a charge transport layer (hole transport layer) between the positive electrode and the charge generation layer is It is preferably configured to prevent movement of electrons to the positive electrode side. The charge transport layer (electron transport layer) between the negative electrode and the charge generation layer prevents the movement of holes to the negative electrode side in order to efficiently move electrons generated in the charge generation layer to the negative electrode. It is preferable to be configured as described above. When it does not have a function to block charge transport, for example, on the positive electrode side, movement of holes and electrons to the positive electrode side occurs in the charge transport layer (hole transport layer) between the positive electrode and the charge generation layer. As a result, deactivation occurs due to recombination of holes and electrons. Similarly, on the negative electrode side, the charge transport layer (electron transport layer) located between the negative electrode and the charge generation layer causes the movement of electrons and holes to the negative electrode side, resulting in deactivation due to recombination of holes and electrons. Can occur.
Therefore, the charge transport layer has a function of blocking the transport of charges opposite to the main transport charge, so that deactivation due to recombination with holes and electrons can be suppressed, and the charge is efficiently taken out to each electrode. It becomes possible.

The material for the charge transport layer is not particularly limited. For example, in the case of the layer configuration of (6), the charge transport layer on the positive electrode side is a hole transport layer, and a compound having a function as a hole acceptor is preferable. A material having a high hole mobility is preferable. The charge transport layer on the negative electrode side is an electron transport layer, preferably a compound having a function as an electron acceptor, and preferably a material having high electron mobility.

The charge generation layer is a layer that absorbs light and generates charges (holes and electrons). For example, a layer (p layer) made of an electron donating p material, an n layer made of an electron accepting n material. Or a mixed layer (i layer) of p material and n material. The i layer can be used alone or in combination as a charge generation layer.

The p material is not particularly limited, but a compound having a function as a hole acceptor is preferable, and a material having a high hole mobility is preferable.
For example, N, N′-bis (3-tolyl) -N, N′-diphenylbenzidine (mTPD), N, N′-dinaphthyl-N, N′-diphenylbenzidine (NPD), 4,4 ′, 4 ′ Amine compounds typified by '-tris (phenyl-3-tolylamino) triphenylamine (MTDATA), etc., phthalocyanine (Pc), copper phthalocyanine (CuPc), zinc phthalocyanine (ZnPc), titanyl phthalocyanine (TiOPc), boron phthalocyanine ( Examples thereof include phthalocyanine complexes such as SubPc), naphthalocyanine complexes, benzoporphyrin (BP), octaethylporphyrin (OEP), platinum octaethylporphyrin (PtOEP), and zinc tetraphenylporphyrin (ZnTPP).
Moreover, if it is a high molecular compound using the application | coating process by a solution, main chain type conjugated polymers, such as methoxyethyl hexyloxy phenylene vinylene (MEHPPV), polyhexyl thiophene (P3HT), cyclopentadithiophene-benzothiadiazole (PCPDTBT) And side chain polymers represented by polyvinylcarbazole and the like.

Of the above-mentioned p materials, a complex is preferable, and a phthalocyanine complex or a naphthalocyanine complex is particularly preferable.
The phthalocyanine complexes are solid skeletons and have excellent weather resistance and heat resistance to light and heat, as is known for phthalocyanine blue, which is a representative pigment. This is because the charge generation layer is a material capable of generating charges by good light absorption and having excellent durability.
The central metal of the complex is not particularly limited, and magnesium (Mg), zinc (Zn), iron (Fe), nickel (Ni), cobalt (Co), tin (Sn), lead (Pb), copper ( It may be a metal atom such as Cu), silicon (Si), palladium (Pd), titanium (Ti), titanyl (TiO), vanadium (V), vanadyl (VO), or an oxometal atom.
As the naphthalocyanine complex, the following compounds are preferable.

The ionization potential (Ip) of the p material is preferably 5.2 to 5.8 eV. As a result, the energy gap with the affinity of the n material of the charge generation layer becomes sufficiently large, and the open-circuit voltage (Voc) of the organic thin film solar cell can be increased. Can be improved.

The n material is not particularly limited, but a compound having a function as a hole donor is preferable, and a material having high electron mobility is preferable.
For example, in the case of organic compounds, fullerene derivatives such as C ₆₀ and C ₇₀ , carbon nanotubes, perylene derivatives, polycyclic quinones, quinacridones, and the like, such as CN-poly (phenylene-vinylene), MEH-CN-PPV, -CN group or CF ₃ group-containing polymer, poly (fluorene) derivative and the like. A material having a small affinity (electron affinity) is preferable. A sufficient open-circuit voltage can be realized by combining materials with low affinity as the n layer.
Fullerenes or fullerene derivatives are preferred in terms of conversion efficiency.

Examples of inorganic compounds include n-type inorganic semiconductor compounds. Specifically, doping semiconductors and compound semiconductors such as n-Si, GaAs, CdS, PbS, CdSe, InP, Nb ₂ O ₅ , WO ₃ , Fe ₂ O ₃ , titanium dioxide (TiO ₂ ), monoxide Examples thereof include titanium oxide such as titanium (TiO) and dititanium trioxide (Ti ₂ O ₃ ), and conductive oxides such as zinc oxide (ZnO) and tin oxide (SnO ₂ ). One or more of these may be used in combination. From the viewpoint of conversion efficiency, titanium oxide is preferably used, and titanium dioxide is particularly preferably used.

The thickness of the charge generation layer is, for example, 0.5 to 200 nm, preferably 1 to 100 nm, and more preferably 2 to 50 nm.

In general, the organic thin film solar cell often has a thin total film thickness, and therefore, the positive electrode and the negative electrode are short-circuited, and the yield of cell fabrication often decreases. In such a case, it is preferable to prevent this by laminating a buffer layer in contact with the electrode. In addition, it is preferable to provide a buffer layer in order to efficiently extract the generated current to the outside.

Preferred compounds for the buffer layer include, for example, aromatic cyclic acid anhydrides represented by NTCDA shown below for low molecular compounds, and poly (3,4-ethylenedioxy) for high molecular compounds. ) Known conductive polymers represented by thiophene: polystyrene sulfonate (PEDOT: PSS), polyaniline: camphorsulfonic acid (PANI: CSA), and the like.

The buffer layer can also have a role of preventing excitons from diffusing to the electrode and being deactivated. Inserting a buffer layer as an exciton blocking layer in this way is effective for increasing efficiency. The exciton blocking layer can be inserted on either the positive electrode side or the cathode side, or both can be inserted simultaneously.
In this case, as a preferable material for the exciton blocking layer, for example, a well-known material for a hole barrier layer or a material for an electron barrier layer for use in an organic EL device can be used. A preferable material for the hole blocking layer is a compound having a sufficiently large ionization potential, and a preferable material for the electron blocking layer is a compound having a sufficiently small electron affinity. Specifically, bathocuproin (BCP), bathophenanthroline (BPhen), and the like, which are well-known materials for organic EL applications, can be used as the cathode-side hole barrier layer material.

Furthermore, you may use the inorganic semiconductor compound illustrated as said n material for a buffer layer. Further, as the p-type inorganic semiconductor compound, CdTe, p-Si, SiC, GaAs, WO ₃ or the like can be used.

The thickness of the buffer layer is, for example, 0.1 to 200 nm, preferably 0.5 to 100 nm, and more preferably 1 to 50 nm.

Although the layer structure of the first organic photoelectric conversion layer and the second organic photoelectric conversion layer has been described, the second organic photoelectric conversion layer is preferably doped with any of the layers constituting the second organic photoelectric conversion layer The donor material which comprises a layer is included, More preferably, a 2nd organic photoelectric converting layer contains a charge transport layer (hole transport layer), and the said hole transport layer contains the donor material which comprises a dope layer.

[Positive electrode and negative electrode]
The material for the positive electrode and the negative electrode is not particularly limited, and a known conductive material can be used. For example, a metal such as tin-doped indium oxide (ITO), fluorine-doped tin oxide (FTO), gold (Au), osmium (Os), palladium (Pd) can be used as the positive electrode, and silver (Ag) can be used as the negative electrode. ), Aluminum (Al), indium (IN), calcium (Ca), platinum (Pt), lithium (Li), and other metals, binary metals such as Mg: Ag, Mg: In, Al: Li, and the positive electrode The following exemplary materials can be used.

In order to obtain highly efficient photoelectric conversion characteristics, it is desirable that at least one surface of the organic thin film solar cell be sufficiently transparent in the sunlight spectrum. The transparent electrode is formed using a known conductive material so as to ensure predetermined translucency by a method such as vapor deposition or sputtering. The light transmittance of the electrode on the light receiving surface is preferably 10% or more. In a preferred configuration of the pair of electrode configurations, one of the electrode portions includes a metal having a high work function, and the other includes a metal having a low work function.

[Intermediate electrode]
In the stacked organic photoelectric conversion device as in the present invention, the intermediate electrode forms an electron-hole recombination zone, and the individual photoelectric conversion units of the stacked device can be separated.
The intermediate electrode serves to prevent the formation of a reverse heterojunction between the n layer of the positive-side photoelectric conversion unit (front cell) and the p-layer of the negative-electrode side photoelectric conversion unit (back cell). The intermediate electrode provides a zone where electrons entering from the photoelectric conversion unit on the positive electrode side and holes from the photoelectric conversion unit on the negative electrode side are recombined, and a photo-induced current can be generated by efficient recombination.

The intermediate electrode is preferably a thin metal layer, and the metal layer may be sufficiently thin and translucent so that light can reach the photoelectric conversion unit (s) on the negative electrode side.
Accordingly, the thickness of the intermediate electrode is preferably about 20 mm or less, more preferably about 5 mm, and the intermediate electrode may be a continuous film of metal or a layer made of isolated metal nanoparticles.

The material for the intermediate electrode is not particularly limited, and materials for forming the positive electrode and the negative electrode can be used. Preferably, Pt and Au, and Ni, Cu, Zn, Pd, Ag, Cd, Mo, V, Ti, In It consists of one or more selected from the metals and oxides of Sn, Ca.
Examples of the oxides of Ni, Cu, Zn, Pd, Ag, Cd, Mo, V, Ti, In, and Sn include, for example, MoO ₃ , VO, ZnO, TiO, TiO ₂ , In ₂ O ₃ , SnO ₂ and V. ₂ O ₅ is mentioned.
More preferably, the intermediate electrode is a layer made of silver, a layer made of gold, a layer made of calcium, a laminated film or mixed film of the above-mentioned metal and molybdenum oxide (MoO ₃ ), or a layer made of an alloy.

[substrate]
The substrate preferably has mechanical and thermal strength and has transparency. For example, a glass substrate and a transparent resin film are mentioned.
Transparent resin films include polyethylene, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, polypropylene, polystyrene, polymethyl methacrylate, polyvinyl chloride, polyvinyl alcohol, polyvinyl butyral, nylon, polyether ether ketone. , Polysulfone, polyethersulfone, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer, polyvinyl fluoride, tetrafluoroethylene-ethylene copolymer, tetrafluoroethylene-hexafluoropropylene copolymer, polychlorotrifluoroethylene, Polyvinylidene fluoride, polyester, polycarbonate, polyurethane, polyimide, polyetherimide, polyimide, polypropylene, etc. It is.

[Production Method of Photoelectric Conversion Element]
For the formation of each layer of the organic photoelectric conversion element of the present invention, dry film forming methods such as vacuum deposition, sputtering, plasma, ion plating, etc .; and wet methods such as spin coating, dip coating, casting, roll coating, flow coating, and ink jet A film formation method can be applied.
Any of the above film forming processes or a combination thereof can be applied. However, since the organic thin film is affected by moisture and oxygen, it is more preferable that the film forming process is unified.

The thickness of each layer is not particularly limited, but may be set to an appropriate thickness.
In general, it is known that the exciton diffusion length of an organic thin film is short. If the film thickness is too thick, the exciton is deactivated before reaching the heterointerface, which may reduce the photoelectric conversion efficiency. . On the other hand, if the film thickness is too thin, pinholes and the like are generated, so that sufficient diode characteristics cannot be obtained and conversion efficiency may be reduced.
Therefore, the film thickness is usually in the range of 1 nm to 10 μm, preferably in the range of 3 nm to 0.2 μm.

The dry film forming method is preferably a known resistance heating method, and for forming the mixed layer, for example, a film forming method by simultaneous vapor deposition from a plurality of evaporation sources is preferable. More preferably, the substrate temperature is controlled during film formation.

In the wet film formation method, an organic solution is prepared by dissolving or dispersing the material forming each layer in an appropriate solvent, and the thin film formed by the wet film formation method is heated at an appropriate temperature to remove the solvent. carry out.
Any solvent can be used as the solvent, for example, halogenated hydrocarbon solvents such as dichloromethane, dichloroethane, chloroform, carbon tetrachloride, tetrachloroethane, chlorobenzene, dichlorobenzene, chlorotoluene, dibutyl ether, tetrahydrofuran, dioxane, Ether solvents such as anisole, alcohol solvents such as methanol, ethanol, propanol, butanol, pentanol, hexanol, cyclohexanol, methyl cellosolve, ethyl cellosolve, ethylene glycol, benzene, toluene, xylene, ethylbenzene, hexane, octane, decane , Hydrocarbon solvents such as tetralin, and ester solvents such as ethyl acetate, butyl acetate, and amyl acetate. These solvents are used alone. It may be used in multiple mixing.
Of the above solvents, hydrocarbon solvents or ether solvents are preferred.

In any organic thin film layer of the organic photoelectric conversion element, an appropriate resin or additive may be used in order to improve film formability and prevent pinholes in the film.
Usable resins include polystyrene, polycarbonate, polyarylate, polyester, polyamide, polyurethane, polysulfone, polymethyl methacrylate, polymethyl acrylate, cellulose and other insulating resins and copolymers thereof, poly-N-vinyl. Examples thereof include photoconductive resins such as carbazole and polysilane, and conductive resins such as polythiophene and polypyrrole.
Examples of the additive include an antioxidant, an ultraviolet absorber, and a plasticizer.

[Manufacture of tandem solar cells]
Example 1
A glass substrate with an ITO transparent electrode having a thickness of 25 mm × 75 mm × 0.7 mm was subjected to ultrasonic cleaning in isopropyl alcohol for 5 minutes, and then UV ozone cleaning was performed for 30 minutes. The glass substrate with a transparent electrode line after washing was mounted on a substrate holder of a vacuum deposition apparatus.
Compound A film (film thickness: 10 nm: charge transport layer), SubNc film (film thickness: 10 nm: p layer), C60 film (film thickness: 20 nm: n layer) on the surface where the transparent electrode line as the positive electrode is formed ), BCP film (film thickness 5 nm, buffer layer), Ag film (film thickness 0.5 nm: intermediate electrode), MoO ₃ film (film thickness 2 nm: intermediate electrode), compound A: compound D film (film thickness 150 nm: dope) Layer), Compound A film (film thickness 10 nm: charge transport layer), SubNc film (film thickness 10 nm: p layer), C60 film (film thickness 20 nm: n layer), BCP film (film thickness 10 nm: buffer layer), metal Al films (thickness 80 nm: negative electrode) were laminated in this order to produce an organic thin film solar cell (element area 0.5 cm ² ).
These layers were laminated by resistance heating vapor deposition, and the vapor deposition rate was 1 Å / s except for the doped layer. The compound A: compound D film as the doped layer is formed by depositing compound A on the donor material at 1 加熱 / s by resistance heating vapor deposition and simultaneously using compound D as the acceptor material at 0.05 Å / s by resistance heating vapor deposition. The film was formed by vapor deposition. The deposition temperature of Compound D at this time was about 210 ° C.

The material used for manufacture of the said organic thin film solar cell is shown below.

With respect to the obtained organic thin film solar cell, the IV characteristic was measured under the AM1.5 condition (light intensity (P _in ) 100 mW / cm ² ) by the following method. Table 2 shows the results of open-circuit voltage (Voc), short-circuit current density (Jsc), fill factor (FF), and conversion efficiency (η).
The conversion efficiency η [%] was calculated from Voc × Jsc × FF / P _in × 100.

Example 2
Of the two SubNc film, and 20nm thickness of SubNc film positive side, of the two _{C 60} film, except that the thickness of the _{C 60} film on the negative electrode side was set to 40nm in the same manner as in Example 1 Organic Thin film solar cells were manufactured and evaluated. The results are shown in Table 2.

Example 3
Of the two SubNc film, and 20nm thickness of SubNc film positive side, of the two _{C 60} film, the thickness of the _{C 60} film on the negative electrode side and 40 nm, instead of the two compounds A film, either A compound B film was formed, and an organic thin film solar cell was manufactured and evaluated in the same manner as in Example 1 except that compound B was used instead of compound A as a donor material for the doped layer. The results are shown in Table 2.

Example 4
An organic thin film solar cell is manufactured in the same manner as in Example 2 except that a compound E film is formed in place of the two compound A films and the compound E is used in place of the compound A as a donor material for the doped layer. And evaluated. The results are shown in Table 2.

Example 5
An organic thin film solar cell was manufactured and evaluated in the same manner as in Example 4 except that the Ag film was formed using Ca. The results are shown in Table 2.

Comparative Example 1
In place of the two compound A films, a compound D film is formed, 4MeO-TPD shown below is used instead of compound A as the donor material of the doped layer, and compound D is used as the acceptor material instead of compound D. An organic thin-film solar cell was produced and evaluated in the same manner as in Example 1 except that C was used. The results are shown in Table 2.
The deposition temperature of compound C forming the dope layer was about 310 ° C.

Comparative Example 2
An organic thin film solar cell was manufactured and evaluated in the same manner as in Example 1 except that Compound C was used instead of Compound D as an acceptor material for the doped layer. The results are shown in Table 2.

Comparative Example 3
In place of the two compound A films, a compound B film is formed, and as the donor material of the doped layer, compound B is used instead of compound A, acceptor material, and compound C is used instead of compound D. In the same manner as in Example 1, an organic thin film solar cell was produced and evaluated. The results are shown in Table 2.

Comparative Example 4
In place of the two compound A films, both mTPD films were formed, mTPD was used instead of compound A as the donor material of the doped layer, and compound C was used instead of compound D as the acceptor material. Organic thin-film solar cells were manufactured and evaluated in the same manner as in Example 1. The results are shown in Table 2.

Comparative Example 5
An organic thin-film solar cell was produced and evaluated in the same manner as in Example 4 except that Compound C was used instead of Compound D as the acceptor material for the doped layer. The results are shown in Table 2.

Comparative Example 6
An organic thin film solar cell was manufactured and evaluated in the same manner as in Example 5 except that Compound C was used instead of Compound D as the acceptor material for the doped layer. The results are shown in Table 2.

In the table, Ip of the compound used for the donor material and | LUMO (A) | of the compound used for the acceptor material were measured by the methods described in this specification.

As shown in the table, the battery including the doped layer satisfying Ip (D) − | LUMO (A) | ≦ 0.7 eV does not decrease the short-circuit current density Jsc even when the doped layer thickness is 150 nm. It became. This means that the thickness of the doped layer of the present invention does not adversely affect the device characteristics, and it can be seen that yield reduction due to leakage or the like can be prevented.
In particular, from Example 2, the doped layer satisfying the relationship of Ip (D) − | LUMO (A) | ≦ 0.7 eV does not lower the Jsc even if the film thickness is 150 nm, which adversely affects the device characteristics. Since it was not given, it was found that by changing the film thickness of the active layer responsible for light generation, element design incorporating the optical interference effect becomes possible, and tandem element characteristics are improved.

Evaluation Example 1
[Production of doped layer single layer element]
A glass substrate with an ITO transparent electrode having a thickness of 25 mm × 75 mm × 0.7 mm was subjected to ultrasonic cleaning in isopropyl alcohol for 5 minutes, and then UV ozone cleaning was performed for 30 minutes. A glass substrate with a transparent electrode line after cleaning is mounted on a substrate holder of a vacuum deposition apparatus, and is a donor material so as to first cover the transparent electrode on the surface on which the transparent electrode line as a positive electrode is formed. Compound A is deposited by resistance heating vapor deposition at 1 Å / s, and at the same time, compound C as an acceptor material is co-evaporated by resistance heating deposition at 0.05 Å / s, thereby forming a 200 nm thick doped layer. did. On the doped layer, metal Al was deposited as a negative electrode in a film thickness of 80 nm to produce a doped layer single layer device (single charge device). The element area was 0.5 cm ² .
The obtained doped layer single layer device was evaluated for JV characteristics. The results are shown in Table 3. FIG. 2 shows the JV characteristics of the doped layer single layer element.

Evaluation Example 2-4
A doped layer single layer device was manufactured and evaluated in the same manner as in Evaluation Example 1 except that the compounds shown in Table 3 were used as the donor material and the acceptor material. The results are shown in Table 3 and FIGS.

As shown in the table, the JV characteristic of the doped layer of Evaluation Example 1 in which the donor material is Compound A and the acceptor material is Compound C is high resistance, whereas the donor material is Compound A. Since the JV characteristic of the doped layer of Evaluation Example 3 in which the acceptor material is Compound D shows an ohmic behavior, the doped layer of Evaluation Example 3 has sufficient intrinsic carriers and has low resistance. It turns out that it is a dope layer.
Similarly, the JV characteristic of the doped layer of Evaluation Example 2 in which the donor material is Compound B and the acceptor material is Compound C is high resistance, whereas the donor material is Compound B and the acceptor material is Compound B. Since the JV characteristic of the doped layer of Evaluation Example 3 in which D is Compound D shows an ohmic behavior, the doped layer of Evaluation Example 4 has sufficient intrinsic carriers, and a low-resistance doped layer and You can see that
Therefore, it can be seen that a doped layer having a relationship of | HOMO (D) | − | LUMO (A) | ≦ 0.7 eV can be a low-resistance doped layer capable of obtaining ohmic JV characteristics.

The photoelectric conversion element and organic thin-film solar cell module of the present invention can be used for watches, mobile phones, mobile personal computers, and the like.

Although several embodiments and / or examples of the present invention have been described in detail above, those skilled in the art will appreciate that these exemplary embodiments and / or embodiments are substantially without departing from the novel teachings and advantages of the present invention. It is easy to make many changes to the embodiment. Accordingly, many of these modifications are within the scope of the present invention.
The contents of the documents described in this specification and the specification of the Japanese application that is the basis of Paris priority of the present application are all incorporated herein.

Claims

A pair of electrodes consisting of a positive electrode and a negative electrode;
An intermediate electrode disposed between the pair of electrodes;
A first organic photoelectric conversion layer disposed between the positive electrode and the intermediate electrode;
A second organic photoelectric conversion layer disposed between the negative electrode and the intermediate electrode;
An organic photoelectric conversion device comprising a doped layer including an acceptor material and a donor material between the intermediate electrode and the second organic photoelectric conversion layer,
The energy Ip (D) of the ionization potential (Ip) of the donor material and the absolute value | LUMO (A) | of the lowest unoccupied molecular orbital (LUMO) of the acceptor material are Ip (D) − | LUMO ( A) | ≦ 0.7 eV,
The organic photoelectric conversion element whose Ip (D) of the said donor material is 5.4 eV or more and 5.6 eV or less.
The organic photoelectric conversion device according to claim 1, wherein the acceptor material is a cyano compound.
The organic photoelectric conversion device according to claim 1 or 2, wherein the acceptor material is a tetracyanoquinodimethane derivative represented by the following formula (1).

(In the formula, each R is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, a dialkylamine group having 2 to 20 carbon atoms, or a cyano group. .)
The organic photoelectric conversion device according to claim 3, wherein at least one of four Rs of the tetracyanoquinodimethane derivative represented by the formula (1) is a cyano group.
The organic photoelectric conversion device according to any one of claims 1 to 4, wherein the donor material is a compound represented by the following formula (2) or formula (3).

(Wherein X 1 , X 2 , Y 1 and Y 2 are each independently a substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms.
R 1 and R 2 are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 ring carbon atoms, A substituted or unsubstituted alkenyl group having 2 to 40 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 40 carbon atoms, a substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms, and 6 to 40 ring atoms A substituted or unsubstituted heteroaryl group, a substituted or unsubstituted alkoxy group having 1 to 40 carbon atoms, a substituted or unsubstituted cycloalkoxy group having 3 to 10 ring carbon atoms, a substituted or unsubstituted 6 to 40 ring carbon atoms, or Unsubstituted aryloxy group, substituted or unsubstituted arylamino group having 6 to 40 ring carbon atoms, or substituted or unsubstituted alkylamino group having 1 to 40 carbon atoms It is. )
6. The organic photoelectric conversion device according to claim 5, wherein the substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms of X 1 , X 2 , Y 1 and Y 2 is a group represented by the following formula (4): .

Wherein R 3 to R 7 are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 3 to 10 ring carbon atoms. Group, substituted or unsubstituted alkenyl group having 2 to 40 carbon atoms, substituted or unsubstituted alkynyl group having 2 to 40 carbon atoms, substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms, number of ring forming atoms A substituted or unsubstituted heteroaryl group having 6 to 40 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 40 carbon atoms, a substituted or unsubstituted cycloalkoxy group having 3 to 10 ring carbon atoms, and 6 to 6 carbon atoms forming a ring 40 substituted or unsubstituted aryloxy groups, substituted or unsubstituted arylamino groups having 6 to 40 ring carbon atoms, or substituted or unsubstituted alkyl groups having 1 to 40 carbon atoms It is an amino group.)
The organic photoelectric conversion device according to any one of claims 1 to 4, wherein the donor material is an aromatic amine derivative represented by the following formula (5).

(In the formula, L is a phenylene group, a biphenylene group, a terphenylene group, or a fluorenylene group having a C 1-6 alkyl group which may form a ring at the 9-position as a substituent.
Ar 1 is a phenyl group substituted with an aryl group selected from a phenyl group, a naphthyl group, and a phenanthryl group, or a naphthyl group,
Ar 2 to Ar 4 are each independently a phenyl group, a phenyl group substituted with a naphthyl group, a biphenyl group, a terphenyl group, a naphthyl group, a naphthyl group substituted with a phenyl group, an anthranyl group, a phenanthryl group, a pyrenyl group, a chrysenyl group, A fluoranthenyl group or a fluorenyl group having a C 1-6 alkyl group which may form a ring at the 9-position as a substituent;
Ar 1 to Ar 4 are different from each other, or any three of Ar 1 to Ar 4 are different from each other.
However, Ar 1 to Ar 4 may be further substituted with an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 1 to 10 carbon atoms, or a halogen atom. )
The organic photoelectric conversion device according to any one of claims 1 to 4, wherein the donor material is an aromatic amine derivative represented by the following formula (5 ').

Wherein L 1 to L 3 are each independently a phenylene group, a biphenylene group, a terphenylene group, or a fluorenylene having an alkyl group having 1 to 6 carbon atoms which may form a ring at the 9-position as a substituent. It is a group.
Ar 1 to Ar 6 are each independently a phenyl group, a phenyl group substituted with a naphthyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenyl group-substituted naphthyl group, an anthranyl group, a phenanthryl group, a pyrenyl group, a chrysenyl group, A fluoranthenyl group or a fluorenyl group having a C 1-6 alkyl group which may form a ring at the 9-position as a substituent.
However, Ar 1 to Ar 6 may be further substituted with an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 1 to 10 carbon atoms, or a halogen atom. )
A pair of electrodes consisting of a positive electrode and a negative electrode;
An intermediate electrode disposed between the pair of electrodes;
A first organic photoelectric conversion layer disposed between the positive electrode and the intermediate electrode;
A second organic photoelectric conversion layer disposed between the negative electrode and the intermediate electrode;
An acceptor material that is a tetracyanoquinodimethane derivative represented by the following formula (1) and a compound represented by the following formula (2) or (3) between the intermediate electrode and the second organic photoelectric conversion layer. An organic photoelectric conversion element comprising a doped layer containing a donor material,
The energy Ip (D) of the ionization potential (Ip) of the donor material and the absolute value | LUMO (A) | of the lowest unoccupied molecular orbital (LUMO) of the acceptor material are Ip (D) − | LUMO ( A) | ≦ 0.7 eV,
The organic photoelectric conversion element whose Ip (D) of the said donor material is 5.4 eV or more and 5.6 eV or less.

(In the formula, each R is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, a dialkylamine group having 2 to 20 carbon atoms, or a cyano group. .)

(Wherein X 1 , X 2 , Y 1 and Y 2 are each independently a substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms.
R 1 and R 2 are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, a substituted or unsubstituted cycloalkyl group having 3 to 10 ring carbon atoms, A substituted or unsubstituted alkenyl group having 2 to 40 carbon atoms, a substituted or unsubstituted alkynyl group having 2 to 40 carbon atoms, a substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms, and 6 to 40 ring atoms A substituted or unsubstituted heteroaryl group, a substituted or unsubstituted alkoxy group having 1 to 40 carbon atoms, a substituted or unsubstituted cycloalkoxy group having 3 to 10 ring carbon atoms, a substituted or unsubstituted 6 to 40 ring carbon atoms, or Unsubstituted aryloxy group, substituted or unsubstituted arylamino group having 6 to 40 ring carbon atoms, or substituted or unsubstituted alkylamino group having 1 to 40 carbon atoms It is. )
The organic photoelectric conversion device according to claim 9, wherein at least one of four Rs of the tetracyanoquinodimethane derivative represented by the formula (1) is a cyano group.
The organic photoelectric device according to claim 9 or 10, wherein the substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms of X 1 , X 2 , Y 1 and Y 2 is a group represented by the following formula (4): Conversion element.

Wherein R 3 to R 7 are each independently a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group having 1 to 40 carbon atoms, or a substituted or unsubstituted cycloalkyl group having 3 to 10 ring carbon atoms. Group, substituted or unsubstituted alkenyl group having 2 to 40 carbon atoms, substituted or unsubstituted alkynyl group having 2 to 40 carbon atoms, substituted or unsubstituted aryl group having 6 to 40 ring carbon atoms, number of ring forming atoms A substituted or unsubstituted heteroaryl group having 6 to 40 carbon atoms, a substituted or unsubstituted alkoxy group having 1 to 40 carbon atoms, a substituted or unsubstituted cycloalkoxy group having 3 to 10 ring carbon atoms, and 6 to 6 carbon atoms forming a ring 40 substituted or unsubstituted aryloxy groups, substituted or unsubstituted arylamino groups having 6 to 40 ring carbon atoms, or substituted or unsubstituted alkyl groups having 1 to 40 carbon atoms It is an amino group.)
A pair of electrodes consisting of a positive electrode and a negative electrode;
An intermediate electrode disposed between the pair of electrodes;
A first organic photoelectric conversion layer disposed between the positive electrode and the intermediate electrode;
A second organic photoelectric conversion layer disposed between the negative electrode and the intermediate electrode;
An acceptor material that is a tetracyanoquinodimethane derivative represented by the following formula (1) and a donor that is an aromatic amine derivative represented by the following formula (5) between the intermediate electrode and the second organic photoelectric conversion layer. An organic photoelectric conversion element comprising a doped layer containing a material,
The energy Ip (D) of the ionization potential (Ip) of the donor material and the absolute value | LUMO (A) | of the lowest unoccupied molecular orbital (LUMO) of the acceptor material are Ip (D) − | LUMO ( A) | ≦ 0.7 eV,
The organic photoelectric conversion element whose Ip (D) of the said donor material is 5.4 eV or more and 5.6 eV or less.

(In the formula, each R is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, a dialkylamine group having 2 to 20 carbon atoms, or a cyano group. .)

(In the formula, L is a phenylene group, a biphenylene group, a terphenylene group, or a fluorenylene group having a C 1-6 alkyl group which may form a ring at the 9-position as a substituent.
Ar 1 is a phenyl group substituted with an aryl group selected from a phenyl group, a naphthyl group, and a phenanthryl group, or a naphthyl group,
Ar 2 to Ar 4 are each independently a phenyl group, a phenyl group substituted with a naphthyl group, a biphenyl group, a terphenyl group, a naphthyl group, a naphthyl group substituted with a phenyl group, an anthranyl group, a phenanthryl group, a pyrenyl group, a chrysenyl group, A fluoranthenyl group or a fluorenyl group having a C 1-6 alkyl group which may form a ring at the 9-position as a substituent;
Ar 1 ~ Ar 4 are different from each other, or one of Ar 1 ~ Ar 4 is any one of the same of Ar 1 ~ Ar 4.
However, Ar 1 to Ar 4 may be further substituted with an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 1 to 10 carbon atoms, or a halogen atom. )
The organic photoelectric conversion device according to claim 12, wherein at least one of four Rs of the tetracyanoquinodimethane derivative represented by the formula (1) is a cyano group.
A pair of electrodes consisting of a positive electrode and a negative electrode;
An intermediate electrode disposed between the pair of electrodes;
A first organic photoelectric conversion layer disposed between the positive electrode and the intermediate electrode;
A second organic photoelectric conversion layer disposed between the negative electrode and the intermediate electrode;
An acceptor material that is a tetracyanoquinodimethane derivative represented by the following formula (1) and an aromatic amine derivative represented by the following formula (5 ′) between the intermediate electrode and the second organic photoelectric conversion layer. An organic photoelectric conversion element comprising a doped layer containing a donor material,
The energy Ip (D) of the ionization potential (Ip) of the donor material and the absolute value | LUMO (A) | of the lowest unoccupied molecular orbital (LUMO) of the acceptor material are Ip (D) − | LUMO ( A) | ≦ 0.7 eV,
The organic photoelectric conversion element whose Ip (D) of the said donor material is 5.4 eV or more and 5.6 eV or less.

(In the formula, each R is independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkyloxy group having 1 to 10 carbon atoms, a dialkylamine group having 2 to 20 carbon atoms, or a cyano group. .)

Wherein L 1 to L 3 are each independently a phenylene group, a biphenylene group, a terphenylene group, or a fluorenylene having an alkyl group having 1 to 6 carbon atoms which may form a ring at the 9-position as a substituent. It is a group.
Ar 1 to Ar 6 are each independently a phenyl group, a phenyl group substituted with a naphthyl group, a biphenyl group, a terphenyl group, a naphthyl group, a phenyl group-substituted naphthyl group, an anthranyl group, a phenanthryl group, a pyrenyl group, a chrysenyl group, A fluoranthenyl group or a fluorenyl group having a C 1-6 alkyl group which may form a ring at the 9-position as a substituent.
However, Ar 1 to Ar 6 may be further substituted with an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkoxycarbonyl group having 1 to 10 carbon atoms, or a halogen atom. )
The organic photoelectric conversion element according to any one of claims 1 to 14, wherein the second organic photoelectric conversion layer contains a donor material of the doped layer.
The organic photoelectric conversion element according to claim 15, wherein the second organic photoelectric conversion layer includes a hole transport layer in contact with the doped layer, and the hole transport layer includes a donor material of the doped layer.
The intermediate electrode is made of Pt and Au, and one or more selected from metals and oxides of Ni, Cu, Zn, Pd, Ag, Cd, Mo, V, Ti, In, Sn, and Ca. The organic photoelectric conversion element according to any one of 16.
An organic thin-film solar cell module using the organic photoelectric conversion element according to any one of claims 1 to 17.