TW202342657A - Organic semiconductor ink, organic film, photoelectric conversion layer, method for producing photoelectric conversion layer, and organic photoelectric conversion element - Google Patents

Abstract

The present invention provides an organic semiconductor ink which contains a p-type organic semiconductor, an n-type organic semiconductor, a compatibilizer and a solvent, and which is characterized in that: the compatibilizer has a fused ring A of 2 to 5 aromatic hydrocarbon rings as the main skeleton, the fused ring A having two or more substituents R that are adjacent to each other; at least one of the substituents R is a monovalent group of a monocyclic aromatic hydrocarbon ring or an aromatic hydrocarbon ring B that is a fused ring of 2 to 4 aromatic hydrocarbon rings, the aromatic hydrocarbon ring B having the same number of or fewer fused rings in comparison to the fused ring A; and the fused ring A and the aromatic hydrocarbon ring B are not present on the same plane.

Description

Organic semiconductor ink, organic film, photoelectric conversion layer, manufacturing method of photoelectric conversion layer and organic photoelectric conversion element

The invention relates to an organic semiconductor ink and an organic film. The present invention also relates to a method for manufacturing a photoelectric conversion layer using the organic semiconductor ink, a photoelectric conversion layer including the organic film, and an organic photoelectric conversion element having the photoelectric conversion layer.

The industry expects that organic photoelectric conversion films that convert incident light energy into electrical energy will be used in solar cells or light sensors (photodiodes). Regarding the organic photoelectric conversion film, PCBM has previously been represented by a conjugated polymer that serves as an electron donor semiconductor (p-type organic semiconductor) and an electron-acceptor semiconductor (n-type organic semiconductor) formed in the film. The bulk heterojunction (BHJ) structure of a mixture of fullerene derivatives is expected to obtain high-performance organic photoelectric conversion films. Organic solar cells with a maximum power conversion efficiency (PCE) of about 11% have been reported.

In recent years, it has been reported that PCE can be further improved by using low-molecular receptors called non-fullerene receptors instead of fullerene derivatives. For example, it is also reported that the energy conversion efficiency from sunlight exceeds 18%.

It is believed that one of the major issues faced by organic photoelectric conversion films is the stability of the BHJ structure. It is considered ideal that in the BHJ structure, the p-type organic semiconductor and the n-type organic semiconductor each have co-continuous crystal domains with a size of approximately 10 to 100 nm in the film. It is mainly determined by the diffusion length of excitons in organic semiconductors. In order to have such a separated structure, it is required that the p-type organic semiconductor and n-type organic semiconductor constituting the BHJ structure have low compatibility and are not excessively mixed with each other. On the other hand, this lower compatibility promotes the growth of phase separation dimensions due to molecular diffusion over time or by heating, resulting in the growth of crystalline domains that are larger than the ideal crystalline domain size. Such phase separation, which can grow to micron size, may cause practical problems, such as degradation of photoelectric conversion characteristics or variation in characteristics between pixels of an image sensor.

In order to deal with this problem, it is known that in order to suppress the molecular diffusion of p-type organic semiconductors and n-type organic semiconductors, at least one of them is cross-linked to reduce thermal mobility, thereby suppressing the growth rate of the phase separation size. technology. For example, Patent Document 1 reports that in addition to p-type organic semiconductors and n-type organic semiconductors, an epoxy cross-linking agent is added to the organic semiconductor ink for cross-linking, thereby improving the thermal stability of the BHJ structure. Prior technical literature patent documents

Patent Document 1: Japanese Patent Application No. 2021-121622

[Problem to be solved by the invention]

However, in the method using a cross-linking component, external energy such as heat or light applied for cross-linking may cause an increase in the phase separation size of the BHJ structure of the photoelectric conversion film or deterioration of the material itself.

The object of the present invention is to provide an organic film that is not prone to phase separation of p-type organic semiconductor and n-type organic semiconductor due to the passage of time or heating without using a cross-linking component; and to provide an organic film suitable for coating method to manufacture the organic semiconductor ink of the organic film. [Technical means to solve problems]

The inventors of the present invention have discovered that p-type organic semiconductors and n-type organic semiconductors are compatible, and that by using a specific compatibilizer that is not prone to self-aggregation or crystallization due to heating or the passage of time, it is possible to provide a An organic film that is unlikely to cause phase separation between p-type organic semiconductors and n-type organic semiconductors due to the passage of time or heating.

The gist of the present invention is as follows.

[1] An organic semiconductor ink, characterized by: containing a p-type organic semiconductor, an n-type organic semiconductor, a compatibilizer and a solvent, and The compatibilizer is the following organic compound: having 2 to 5 condensed rings A of an aromatic hydrocarbon ring with two or more adjacent substituents R as the main skeleton, At least one of the substituents R is a valence group of the aromatic hydrocarbon ring B. The aromatic hydrocarbon ring B is a single aromatic hydrocarbon ring, or the number of condensed rings is the same as or less than that of the condensed ring A. 2 to 4 condensed rings of hydrocarbon rings, The condensed ring A and the aromatic hydrocarbon ring B do not exist on the same plane.

[2] An organic semiconductor ink containing a p-type organic semiconductor, an n-type organic semiconductor, a compatibilizer and a solvent, and The compatibilizer has a main skeleton of 2 to 5 condensed rings A of an aromatic hydrocarbon ring with two or more substituents R adjacent to each other. The substituent R is a monovalent group of the aromatic hydrocarbon ring B', which is a single aromatic hydrocarbon ring or 2 to 4 condensed rings of aromatic hydrocarbon rings.

[3] The organic semiconductor ink as described in [2], wherein the substituent R is a valent group of the aromatic hydrocarbon ring B, and the number of condensed rings of the aromatic hydrocarbon ring B is the same as or less than that of the condensed ring A. 2 to 4 condensed rings of aromatic hydrocarbon rings.

[4] The organic semiconductor ink according to any one of [1] to [3], wherein all of the above R are monovalent groups of aromatic hydrocarbon rings.

[5] The organic semiconductor ink according to [4], wherein all of the above-mentioned R's are phenyl groups.

[6] The organic semiconductor ink according to [5], wherein the compatibilizer is selected from the group consisting of 1,2,3,4-tetraphenylnaphthalene and 1-methyl-3,4-diphenylnaphthalene.

[7] The organic semiconductor ink according to any one of [1] to [6], wherein the p-type organic semiconductor and the n-type organic semiconductor do not have a crosslinking group.

[8] The organic semiconductor ink according to any one of [1] to [7], wherein the p-type organic semiconductor is a polymer compound.

[9] The organic semiconductor ink according to [8], wherein the p-type organic semiconductor is a polymer compound with a weight average molecular weight of 50,000 to 400,000.

[10] The organic semiconductor ink according to [8] or [9], wherein the polymer compound is a polymer compound represented by the following formula (II).

[Chemical 1]

(In formula (II), n is a positive number)

[11] The organic semiconductor ink according to any one of [1] to [10], wherein the n-type organic semiconductor is a non-fullerene-type semiconductor.

[12] The organic semiconductor ink according to [11], wherein the non-fullerene semiconductor is a compound represented by the following formula (I) and a polymer of a compound represented by the following formula (I) At least any compound.

[Chemicalization 2]

(In formula (I), A represents an atom selected from Group 14 of the periodic table; X ¹ to X ⁴ each independently represent a hydrogen atom or a halogen atom; R ^1a and R ^1b each independently represent a chain alkyl group; R ² ~R ⁵ each independently represents a chain alkyl group, a chain alkoxy group, a chain thioalkyl group, or a hydrogen atom)

[13] The organic semiconductor ink according to any one of [1] to [12], wherein the content ratio (mass ratio) of the compatibilizer to the p-type organic semiconductor is 0.1 or more and 10.0 or less.

[14] The organic semiconductor ink according to any one of [1] to [13], wherein the solvent is xylene.

[15] An organic film, characterized by: containing a p-type organic semiconductor, an n-type organic semiconductor and an organic compound, and The organic compound has a main skeleton of 2 to 5 condensed rings A of aromatic hydrocarbon rings with two or more substituents R adjacent to each other. At least one of the substituents R is a valence group of the aromatic hydrocarbon ring B. The aromatic hydrocarbon ring B is a single aromatic hydrocarbon ring, or the number of condensed rings is the same as or less than that of the condensed ring A. 2 to 4 condensed rings of hydrocarbon rings, The condensed ring A and the aromatic hydrocarbon ring B do not exist on the same plane.

[16] An organic film containing a p-type organic semiconductor, an n-type organic semiconductor and an organic compound, and The organic compound has a main skeleton of 2 to 5 condensed rings A of aromatic hydrocarbon rings with two or more substituents R adjacent to each other. The substituent R is a monovalent group of the aromatic hydrocarbon ring B', which is a single aromatic hydrocarbon ring or 2 to 4 condensed rings of aromatic hydrocarbon rings.

[17] The organic film as described in [16], wherein the substituent R is a monovalent group of the aromatic hydrocarbon ring B, and the number of condensed rings of the aromatic hydrocarbon ring B is the same as or less than that of the condensed ring A. 2 to 4 condensed rings of aromatic hydrocarbon rings.

[18] A photoelectric conversion layer including the organic film according to any one of [15] to [17].

[19] A method for manufacturing a photoelectric conversion layer, which includes the step of applying the organic semiconductor ink according to any one of [1] to [14].

[20] An organic photoelectric conversion element including a photoelectric conversion layer including the organic film according to any one of [15] to [17]. [Effects of the invention]

Since the organic semiconductor ink of the present invention contains p-type organic semiconductors, n-type organic semiconductors and components that make them compatible, even after an organic film is formed from the organic semiconductor ink, the p-type organic semiconductor and the n-type organic semiconductor can be suppressed. of phase separation. In this way, since the organic semiconductor ink of the present invention contains a specific compatibilizer, there is no need to add a cross-linking component to the organic semiconductor ink and provide heat for cross-linking in order to kinetically suppress phase separation as in the previous invention. Or external energy such as light. Therefore, organic photoelectric conversion layers and organic photoelectric conversion elements with excellent heat resistance and stability can be produced more economically than before.

Hereinafter, the embodiment will be described in detail. The descriptions of the constituent elements described below are representative examples of embodiments of the present invention, and the present invention is not limited to these contents.

[Organic semiconductor ink] The organic semiconductor ink of the present invention is characterized by containing p-type organic semiconductor, n-type organic semiconductor, specific compatibilizer and solvent.

＜Compatibilizer＞ The compatibilizer (hereinafter, sometimes referred to as "compatible agent I") used in the first embodiment of the present invention is an organic compound composed of an aromatic hydrocarbon ring having two or more substituents R adjacent to each other. The main skeleton is 2 to 5 condensed rings A, and at least one of the substituents R is a monovalent group of an aromatic hydrocarbon ring B. The aromatic hydrocarbon ring B is a single ring of an aromatic hydrocarbon ring, or the number of condensed rings is the same as that of the aromatic hydrocarbon ring. The condensed ring A is the same as or less than 2 to 4 condensed rings of the aromatic hydrocarbon ring, and the condensed ring A and the aromatic hydrocarbon ring B do not exist on the same plane. The compatibilizer (hereinafter, sometimes referred to as "compatible agent II") used in the second embodiment of the present invention is an organic compound composed of an aromatic hydrocarbon ring having two or more substituents R adjacent to each other. The main skeleton is 2 to 5 condensed rings A, and the substituent R is a valent group of the aromatic hydrocarbon ring B'. The aromatic hydrocarbon ring B' is a single aromatic hydrocarbon ring, or 2 to 5 aromatic hydrocarbon rings. 4 condensed rings. Hereinafter, "compatible agent I" and "compatible agent II" may be collectively referred to as "the compatibilizer of the present invention".

Here, the "main skeleton" refers to the condensed ring skeleton that forms the largest skeleton among the organic compounds of the compatibilizer. In addition, the "same plane" plane refers to the π conjugated plane of the aromatic hydrocarbon ring. Therefore, "the condensed ring A and the aromatic hydrocarbon ring B do not exist on the same plane" means that the π conjugated plane of the condensed ring A and the π conjugated plane of the aromatic hydrocarbon ring B do not exist on the same plane. For example, the monovalent substituent R on the aromatic hydrocarbon ring B can prevent free rotation around the single bond bonded to the condensed ring A through its steric hindrance (steric restriction) with the substituent R on the adjacent condensed ring A. , refers to the state in which the π conjugated plane of the condensed ring A and the π conjugated plane of the aromatic hydrocarbon ring B are not arranged on the same plane. In addition, "aromatic hydrocarbon ring" refers to an aromatic ring, and includes heterocyclic rings in addition to hydrocarbon rings in the so-called narrow sense. However, if the impact on photoelectric conversion characteristics is considered, a hydrocarbon ring in a narrow sense is preferred over a heterocyclic ring.

(mechanism) In order for a compound to function as a compatibilizer between a p-type organic semiconductor and an n-type organic semiconductor, the compound must first be compatible with both the p-type organic semiconductor and the n-type organic semiconductor. Generally, both p-type organic semiconductors and n-type organic semiconductors have a conjugated skeleton as the main skeleton, so the compatibilizer is also required to have a conjugated skeleton. On the other hand, since many unsubstituted conjugated compounds such as naphthalene and pyrene have a planar structure and high structural symmetry, they are easily crystallized when the coating is dried or the film is heated, and cannot be used as p-type compounds. How the compatibilizer between organic semiconductors and n-type organic semiconductors functions. In contrast, since at least two conjugated backbones are connected and are not arranged on the same plane, the conjugated compound in a twisted position relationship maintains the compatibility of p-type organic semiconductors and n-type organic semiconductors, and itself It does not have strong crystallinity, so it effectively functions as a compatibilizer between p-type organic semiconductors and n-type organic semiconductors.

(Condensed ring A) The condensed ring A constituting the main skeleton of the compatibilizer of the present invention is 2 to 5 condensed rings of aromatic hydrocarbon rings. In terms of chemical stability, the number of condensed rings of condensed ring A is preferably larger. On the other hand, in terms of compatibility between the p-type organic semiconductor and the n-type organic semiconductor, it is preferable to have less. Therefore, specifically, the number of condensed rings of the condensed ring A is 2 to 5, preferably 2 to 4. The total number of carbon atoms in the condensed ring A of the main skeleton is preferably 10 to 18.

The condensed ring A as the main skeleton only needs to contain an aromatic hydrocarbon ring, and the condensed ring A as a whole forms a π conjugated plane. For example, naphthalene, azulene, phenanthrene, and anthracene have the following structural formulas: , fluoranthene, pyrene, glycerol, benzo[b]fluoranthene, benzo[a]pyrene, perylene, etc. Examples of the heterocyclic ring include quinoline, phenanthroline, benzodithiophene, naphthodithiophene, and the like.

[Chemical 3]

(Substituent R) The condensed ring A as the main skeleton of the compatibilizer of the present invention has two or more substituents R adjacent to each other. Here, "adjacent" refers to bonding with an adjacent carbon atom on the condensed ring A of the main skeleton. In the compatibilizer I according to the first embodiment of the present invention, at least one of the substituents R is a monovalent group of the aromatic hydrocarbon ring B, and the aromatic hydrocarbon ring B is a monocyclic or condensed aromatic hydrocarbon ring. 2 to 4 condensed rings with the same ring number as the condensed ring A or less than the aromatic hydrocarbon ring. Here, the monovalent group of the aromatic hydrocarbon ring B refers to a group in which the aromatic hydrocarbon ring B is directly bonded to the condensed ring A of the main skeleton through a single bond. As long as the characteristics as a compatibilizer are not impaired, the aromatic hydrocarbon ring B may further have a substituent. Examples of the substituents that the aromatic hydrocarbon ring B may have include an alkyl group, an alkoxy group, and a thioalkyl group.

In the compatibilizer II of the second embodiment of the present invention, at least one of the substituents R is a valent group of the aromatic hydrocarbon ring B', and the aromatic hydrocarbon ring B' is a monocyclic aromatic hydrocarbon ring, Or 2 to 4 condensed rings of aromatic hydrocarbon rings. Here, the monovalent group of the aromatic hydrocarbon ring B' refers to a group in which the aromatic hydrocarbon ring B' is directly bonded with the condensed ring A of the main skeleton through a single bond. As long as the characteristics as a compatibilizer are not impaired, the aromatic hydrocarbon ring B' may further have a substituent. Examples of the substituents that the aromatic hydrocarbon ring B' may have include alkyl groups, alkoxy groups, and thioalkyl groups. wait. In the second embodiment of the present invention, the aromatic hydrocarbon ring B' is also preferably an aromatic hydrocarbon ring B which is an aromatic hydrocarbon ring having the same number of condensed rings as or less than 2 to 4 condensed rings of the condensed ring A. .

In the monovalent group of the aromatic hydrocarbon ring B or the aromatic hydrocarbon ring B', examples of the monocyclic group include phenyl group, thienyl group, pyridyl group, and the like. Examples of the 2-4 fused ring groups of aromatic hydrocarbon rings include those having 2 to 4 fused rings in the fused rings described above as specific examples of the fused ring A.

Regarding the substituents R of the condensed ring A of the main skeleton other than the monovalent group of the aromatic hydrocarbon ring B or the aromatic hydrocarbon ring B', there is no special requirement as long as the characteristics as a compatibilizer are not impaired. Limitation, it may be a group selected from the valent groups of the above-mentioned aromatic hydrocarbon ring B or aromatic hydrocarbon ring B', and may also be an alkyl group, an alkoxy group, a thioalkyl group, etc.

P-type organic semiconductors and n-type organic semiconductors are generally highly hydrophobic. Therefore, from the viewpoint of compatibility with these semiconductors, it is preferable that the substituent R other than the valent group of the aromatic hydrocarbon ring B or the aromatic hydrocarbon ring B′ is relatively hydrophobic. Examples include Alkyl group, aromatic hydrocarbon group, etc. In addition, in order to prevent the π conjugated plane of condensed ring A from being arranged on the same plane as the π conjugated plane of aromatic hydrocarbon ring B or aromatic hydrocarbon ring B', except for aromatic hydrocarbon ring B or aromatic hydrocarbon ring B' The substituent R other than a monovalent group is preferably a conjugated substituent such as an aromatic hydrocarbon group such as a phenyl group, naphthyl group or anthracenyl group, or an aromatic heterocyclic group such as a thienyl group, a pyrrolyl group or a furyl group, and more preferably Aromatic hydrocarbon groups in a narrow sense such as phenyl, naphthyl, and anthryl, and phenyl are more preferred. That is, the substituent R other than the monovalent group of the aromatic hydrocarbon ring B or the aromatic hydrocarbon ring B' is preferably a monovalent group of the aromatic hydrocarbon ring, and more preferably is a phenyl group.

The number of substituents R that the condensed ring A of the main skeleton has is not particularly limited, as long as it is 2 or more. The number of substituents R is more preferably 3 or more, most preferably 4 or more. By having more substituents R adjacent to each other, the volume of the compatibilizer is increased, which can further suppress the aggregation of p-type organic semiconductors and the aggregation of n-type organic semiconductors.

(molecular weight) The compatibilizer of the present invention preferably has a relatively high molecular weight in terms of a relatively high melting point or boiling point and in terms of the compatibilizer being less likely to disappear from the composition or the photoelectric conversion layer due to volatilization or sublimation. On the other hand, in terms of solubility in solvents, the molecular weight is preferably lower. Therefore, the molecular weight of the compatibilizer of the present invention is preferably 200 or more, more preferably 300 or more, further preferably 400 or more, and preferably 10,000 or less, more preferably 5,000 or less, and still more preferably 2,500 or less.

(HOMO and LOMO) The HOMO (Highest Occupied Molecular Orbital, highest occupied molecular orbital) of the compatibilizer of the present invention is preferably lower than the HOMO of the n-type organic semiconductor. The LUMO (Lowest Unoccupied Molecular Orbital) of the compatibilizer of the present invention is preferably higher than the LUMO of the p-type organic semiconductor. This is to prevent the electron orbits of the compatibilizer of the present invention from acting as trap energy levels for carriers during the photoelectric conversion process, thereby resulting in a reduction in photoelectric conversion characteristics.

(specific example) Preferable specific examples of the compatibilizer of the present invention include the following 1,2,3,4-tetraphenylnaphthalene, 1-methyl-3,4-diphenylnaphthalene, and 1,2 -Diphenylanthracene, 1,2-diphenylnaphthalene, 1,2,3,4-tetraphenylanthracene, 1,2-diphenylcondensed tetraphenyl, 1,2,6,7-tetraphenyl Pyrene, etc., but are not subject to any such restrictions.

[Chemical 4]

As representative examples among the above-mentioned exemplary compounds, the following shows the use of p-1,2,3,4-tetraphenylnaphthalene, 1-methyl-3,4-diphenylnaphthalene and 1,2-diphenylnaphthalene. Anthracene is a molecular model of the three-dimensional structure created using the molecular modeling software Spartan (version 18) and applying the semi-empirical molecular orbital method. It can be seen that the ring belonging to the condensed ring A and the ring belonging to the aromatic hydrocarbon ring B do not exist on the same plane.

[Chemistry 5]

The organic semiconductor ink of the present invention may contain only one type of compatibilizer of the present invention, or may contain two or more types with different condensed rings A or substituents R of the main skeleton.

＜p-type organic semiconductor＞ The p-type organic semiconductor is not particularly limited, and a known organic semiconductor compound can be used, preferably a donor semiconductor, and typically an organic semiconductor (compound). Examples of p-type organic semiconductors include hole-transporting organic compounds that are p-type conjugated polymers, and electron-donating compounds can be used.

Specific examples of skeleton structures with excellent electron hole transport properties include: carbazole structure, thiophene structure, benzodithiophene structure, thienothiophene structure, dibenzofuran structure, triarylamine structure, naphthalene structure, phenanthrene structure and Pyrene structure etc. Among these, compounds that can easily form a film by being mixed with an n-type organic semiconductor to be described later and then applied are particularly preferred.

The p-type organic semiconductor may be a polymer compound, or may have units derived from donor monomers (benzodithiophene, cyclopentadithiophene, dithienothiole, etc.) and units derived from acceptor monomers. Copolymers of units (benzo[1,2-b:4,5-b']dithiophene-4,8-dione, acyl imidethiophene, etc.). From the viewpoint that the photoelectric conversion layer can be easily produced by a coating method, the p-type organic semiconductor is preferably a polymer compound.

As a specific p-type organic semiconductor, for example, a semiconductor compound represented by the following formula (II) can be used. Furthermore, in formula (II), n is a positive number.

[Chemical 6]

In order to improve the characteristics as a p-type semiconductor, the weight average molecular weight of the p-type organic semiconductor used in the present invention is preferably higher. Specifically, it is preferably 50,000 or more, more preferably 100,000 or more, and further preferably 150,000 or more. . On the other hand, in terms of solubility in a solvent, the weight average molecular weight of the p-type organic semiconductor is preferably low, specifically, it is preferably 400,000 or less, and more preferably 300,000 or less. Here, the weight average molecular weight of the p-type organic semiconductor is a value determined by size exclusion chromatography.

Specific examples of the p-type organic semiconductor used in the present invention include the following polymer compounds, but are not limited in any way.

[Chemical 7]

＜n-type organic semiconductor＞ N-type semiconductors are acceptor semiconductors, mainly represented by electron-transporting compounds, which refer to semiconductor compounds with electron-accepting properties. Specifically, an n-type organic semiconductor refers to a compound with a large electron affinity when two compounds are brought into contact and used. Therefore, any compound can be used as long as the acceptor compound has electron-accepting properties.

Specific examples of n-type semiconductors include condensed aromatic carbocyclic compounds (naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, pyrene derivatives, perylene derivatives, and fluoranthene derivatives); Heterocyclic compounds with 5 to 7 members of nitrogen atom, oxygen atom, and sulfur atom (such as pyridine, pyridine, pyrimidine, pyrimidine, trisulfide, quinoline, quinoline, quinazoline, pyridine, eudoline, isoline Quinoline, pteridine, acridine, phenanthroline, phenanthroline, tetrazole, pyrazole, imidazole, thiazole, thiazole, indazole, benzimidazole, benzotriazole, benzothiazole, benzothiazole, carbide Azole, purine, triazolopyridine, triazolopyrimidine, tetraazaindane, oxadiazole, imidazopyridine, pyrrolidine, pyrrolopyridine, thiadiazolopyridine, dibenzazepine, triphenzo Nitrogen, etc.); polyarylene compounds; fluorine compounds; cyclopentadiene compounds; metal complexes with silanyl compounds and nitrogen-containing heterocyclic compounds as ligands, etc. Without being limited to these examples, as mentioned above, any compound that has a higher electron affinity than a compound used as a donor semiconductor can be used as an acceptor semiconductor.

Due to the large volume of the fullerene skeleton, when a bulk heterojunction structure is used to improve photoelectric conversion efficiency, the distance from the p-type semiconductor is likely to increase, and the photoelectric conversion efficiency may be reduced.

Therefore, regarding the n-type semiconductor in the present invention, it is preferable that the ratio of the n-type semiconductor having a fullerene skeleton is smaller than that of the n-type semiconductor not having a fullerene skeleton. Specifically, the ratio of the n-type semiconductor having a fullerene skeleton in the n-type semiconductor is preferably 10% by mass or less, and more preferably the n-type semiconductor does not substantially contain non-fullerene having a fullerene skeleton. type semiconductor.

Here, "substantially no fullerene skeleton" means that the non-fullerene n-type semiconductor is responsible for the transport of electrons in the charge generated in the photoelectric conversion layer, and may be contained in a small amount in order to improve the morphology of the photoelectric conversion layer. For this purpose, the amount of the n-type semiconductor containing a fullerene skeleton contained in the total amount of the n-type organic semiconductor is usually 5 mass% or less, preferably 2 mass% or less.

Especially from the viewpoint of compatibility with p-type organic semiconductors and ease of formation of the BHJ-type photoelectric conversion layer, the n-type organic semiconductor used in the present invention preferably contains a compound represented by the following formula (I) and at least any one compound among the polymers of the compounds represented by the following formula (I).

[Chemical 8]

(In formula (I), A represents an atom selected from Group 14 of the periodic table, X ¹ to X ⁴ each independently represents a hydrogen atom or a halogen atom, R ^1a and R ^1b each independently represents a chain alkyl group, R ² ~R ⁵ each independently represents a chain alkyl group, a chain alkoxy group, a chain thioalkyl group, or a hydrogen atom)

A represents an atom selected from group 14 of the periodic table. In terms of the stability of the compound, A is preferably a carbon atom and a silicon atom. X ¹ to X ⁴ each independently represent a hydrogen atom or a halogen atom. From the viewpoint of easily controlling the HOMO/LUMO of the n-type organic semiconductor, X ¹ to X ⁴ are preferably halogen atoms. R ^1a and R ^1b each independently represent a chain alkyl group. From the perspective of improving the solubility of the n-type organic semiconductor, the number of carbon atoms of R ^1a and R ^1b is preferably larger. From the perspective of the ease of formation of the BHJ-type photoelectric conversion layer of the p-type organic semiconductor, the carbon number is preferably larger. It is better to have less. The carbon number of R ^1a and R ^1b is preferably 8 or more, more preferably 10 or more, further preferably 12 or more, and preferably 24 or less, more preferably 20 or less, still more preferably 18 or less.

Examples of chain alkyl groups having 8 to 24 carbon atoms include linear alkyl groups such as n-octyl, n-decyl, lauryl, myristyl, palmityl, and stearyl; 2-ethylhexyl, 2 -Branched primary alkyl groups such as butyloctyl and secondary alkyl groups such as 2-octyl, 2-nonyl, 2-decyl, etc. Among these, a linear alkyl group or a branched primary alkyl group is preferred, and 2-ethylhexyl or 2-butyloctyl is particularly preferred.

R ² to R ⁵ each independently represent a chain alkyl group, a chain alkoxy group, a chain thioalkyl group, or a hydrogen atom. In terms of improving the solubility of the n-type organic semiconductor, R ² to R ⁵ are preferably chain alkyl groups, chain alkoxy groups and chain thioalkyl groups.

When R ² to R ⁵ are an alkyl group, an alkoxy group or a thioalkyl group, the number of carbon atoms is preferably larger in order to improve the solubility of the n-type organic semiconductor. Compared with the p-type organic semiconductor, From the viewpoint of the ease of formation of the BHJ-type photoelectric conversion layer, it is preferable to have a smaller number. The carbon number of R ^1a and R ^1b is preferably 8 or more, more preferably 10 or more, further preferably 12 or more, and preferably 24 or less, more preferably 20 or less, still more preferably 18 or less. R ² to R ⁵ are preferably an alkoxy group, more preferably an alkoxy group having 8 to 24 carbon atoms. Specific examples include 2-ethylhexyloxy or palmitoxy.

From the viewpoint of compatibility with p-type organic semiconductors and ease of formation of the BHJ-type photoelectric conversion layer, R ^1a and R ^1b are preferably the same group, and R ² to R ⁵ are preferably two or more different ones. base.

Specific examples of the n-type organic semiconductor used in the present invention include the following compounds, but are not limited thereto.

[Chemical 9]

<Ratio of p-type organic semiconductor and n-type organic semiconductor> Regarding the ratio of p-type organic semiconductors and n-type organic semiconductors contained in the organic semiconductor ink of the present invention, if there are more p-type organic semiconductors, the sensitivity in the near-infrared region tends to be excellent, and if there are more n-type organic semiconductors, the sensitivity will be excellent in the near-infrared region. If it is too large, it will be difficult to generate dark current. The ratio of the p-type organic semiconductor and the n-type organic semiconductor contained in the organic semiconductor ink of the present invention is preferably based on the mass ratio of the n-type organic semiconductor to the p-type organic semiconductor (n-type organic semiconductor/p-type organic semiconductor mass ratio). It is 0.5 times or more, more preferably 1.0 times or more, and it is preferably 3.5 times or less, more preferably 3.0 times or less.

＜Content of compatibilizer＞ Regarding the content of the compatibilizer of the present invention in the organic semiconductor ink of the present invention, the compatibilizer of the present invention will improve the compatibility of p-type organic semiconductor and n-type organic semiconductor, as long as it is not easy to cause damage due to heating or the passage of time. There are no special restrictions on the phase separation caused. However, from the viewpoint that the stabilizing effect of the BHJ structure is likely to occur due to the inclusion of a compatibilizer, a larger amount is preferred. The mass ratio of the compatibilizer of the present invention in the organic semiconductor ink of the present invention relative to the p-type organic semiconductor is preferably 0.1 times or more, more preferably 0.3 times or more, further preferably 0.5 times or more, most preferably is more than 1.0 times. On the other hand, in terms of preventing crystallization of the compatibilizer itself in the organic film produced using the organic semiconductor ink of the present invention, the amount is preferably less. The mass ratio of the compatibilizer of the present invention in the organic semiconductor ink of the present invention relative to the p-type organic semiconductor is preferably 10.0 times or less, more preferably 7.0 times or less, and still more preferably 5.0 times or less.

＜Solvent＞ The organic semiconductor ink of the present invention can be used as a coating liquid by further containing a solvent. The solvent contained in the organic semiconductor ink of the present invention only needs to be a liquid that can dissolve p-type organic semiconductors, n-type organic semiconductors and the compatibilizer of the present invention.

Examples of the solvent include aromatic hydrocarbon solvents such as toluene, xylene, mesitylene, and cyclohexylbenzene; halogen-containing aromatic hydrocarbon solvents such as chlorobenzene and o-dichlorobenzene; and 1,2-dichloro Halogen-containing aliphatic hydrocarbon solvents such as ethane; aliphatic ether solvents such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethyl Oxybenzene, 1,3-dimethoxybenzene, anisole, phenylethyl ether, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylbenzene Aromatic ether solvents such as methyl ether and 2,4-dimethylanisole; aliphatic ester solvents such as ethyl acetate, n-butyl acetate, ethyl lactate, n-butyl lactate, phenyl acetate, and propionic acid Aromatic ester solvents such as phenyl ester, methyl benzoate, ethyl benzoate, isopropyl benzoate, propyl benzoate, n-butyl benzoate, etc.

When using a solvent, one type may be used alone or two or more types may be used in combination.

Among these solvents, from the viewpoint of the solubility of p-type organic semiconductors and n-type organic semiconductors, aromatic solvents are preferred, aromatic non-halogen solvents are particularly preferred, and toluene and xylene are particularly preferred. , mesitylene, mesitylene.

＜Other ingredients＞ The organic semiconductor ink of the present invention, in addition to the above-mentioned p-type organic semiconductor, n-type organic semiconductor, compatibilizer and solvent of the present invention, may also contain components such as stabilizers or tackifiers if necessary. When the organic semiconductor ink of the present invention contains these other components, in order to easily fully express the original effect of the organic semiconductor ink, the p-type organic semiconductor, n-type organic semiconductor and phase of the present invention in the organic semiconductor ink The total amount of the volumetric agent is preferably 90% by mass or more.

＜Solid content concentration＞ In order to achieve excellent formation efficiency of the photoelectric conversion layer, the solid component concentration contained in the organic semiconductor ink of the present invention, that is, the content of components other than the solvent in the organic semiconductor ink is preferably high. On the other hand, in order to easily obtain a uniform ink with high stability and excellent coatability, the amount is preferably less. The solid content concentration of the organic semiconductor ink is preferably 10 mg/mL or more, more preferably 15 mg/mL or more, and preferably 150 mg/mL or less, more preferably 60 mg/mL or less.

＜Manufacturing method of organic semiconductor ink＞ The organic semiconductor ink of the present invention can be produced by mixing the above-mentioned p-type organic semiconductor, n-type organic semiconductor, the compatibilizer of the present invention, and optional other components in a solvent so as to have a predetermined concentration. At this time, there is no particular restriction on the order in which the components are added, as long as a uniform ink can be obtained.

In the step of mixing the components, it is preferable to perform heating in order to easily obtain a liquid with a uniform composition in a shorter time. From the perspective of improving the solubility of each component, the temperature during heating is preferably high, and from the perspective of less likely to cause deterioration of each component or volatilization of the solvent, low temperature is preferred. The temperature during heating is preferably about 50 to 200°C. Moreover, when mixing each component, it is preferable to stir. After mixing, incompletely dissolved components can be removed by filtration through a filter. When heating is performed during mixing, the mixture can be returned to room temperature (25°C) and then filtered. In terms of the stability of the ink, it is best to leave the mixed liquid at room temperature (25°C) for 1 minute to 24 hours.

＜Uses of organic semiconductor ink＞ The organic semiconductor ink of the present invention can form a photoelectric conversion layer with excellent stability of the BHJ structure by containing a specific compatibilizer, and can be suitably used to form the photoelectric conversion layer of an organic photoelectric conversion element.

[Organic film] The organic film of the present invention is characterized in that it is a film containing a p-type organic semiconductor, an n-type organic semiconductor and an organic compound, and the organic compound is the compatibilizer of the present invention. That is, the organic film according to the first embodiment of the present invention is characterized in that it is an organic film including a p-type organic semiconductor, an n-type organic semiconductor, and an organic compound, and the organic compound has two or more adjacent substituents. The 2-5 condensed rings A of the aromatic hydrocarbon ring of R are the main skeleton, and at least one of the substituents R is a valent group of the aromatic hydrocarbon ring B. The aromatic hydrocarbon ring B is a single ring of the aromatic hydrocarbon ring. Or the number of condensed rings is the same as the condensed ring A or less than 2 to 4 condensed rings of the aromatic hydrocarbon ring, and the condensed ring A and the aromatic hydrocarbon ring B do not exist on the same plane. Furthermore, the organic film according to the second embodiment of the present invention is characterized in that it is an organic film including a p-type organic semiconductor, an n-type organic semiconductor and an organic compound, and the organic compound has two or more adjacent substituents. The 2-5 condensed rings A of the aromatic hydrocarbon ring of R are the main skeleton. At least one of the substituents R is a valent group of the aromatic hydrocarbon ring B'. The aromatic hydrocarbon ring B' is a monovalent group of the aromatic hydrocarbon ring. ring, or 2 to 4 condensed rings of aromatic hydrocarbon rings. In the second embodiment of the present invention, the aromatic hydrocarbon ring B' is also preferably an aromatic hydrocarbon ring B which is an aromatic hydrocarbon ring having the same number of condensed rings as or less than 2 to 4 condensed rings of the condensed ring A. . The p-type organic semiconductor, n-type organic semiconductor and organic compound contained in the organic film of the present invention, including their contents, are the same as those in the organic semiconductor ink of the present invention without removing the solvent.

The organic film of the present invention can be produced by removing the solvent from the organic semiconductor ink of the present invention. Specifically, the organic semiconductor ink of the present invention can be used and produced by a coating method. The organic film of the present invention can be used as a photoelectric conversion layer.

The photoelectric conversion layer of the present invention includes the organic film of the present invention, and can be produced by a coating method using the organic semiconductor ink of the present invention. That is, the method of manufacturing a photoelectric conversion layer including the organic film of the present invention includes the step of applying the organic semiconductor ink of the present invention.

[Photoelectric conversion layer] The photoelectric conversion layer of the present invention includes the organic film of the present invention, and is a layer coated with the organic semiconductor ink of the present invention as described above.

The photoelectric conversion layer of the present invention can be coated on the surface on which the photoelectric conversion layer is formed (usually on the electrode surface of the organic photoelectric conversion element of the present invention described later, or on other layers such as the hole transport layer formed on the electrode). The organic semiconductor ink of the present invention is used to form a film. Here, the formed coating film may be heated and dried if necessary.

The coating method is not particularly limited, and specific examples include spin coating. In this case, the spin coating conditions may be appropriately determined according to common practice, taking into account the viscosity of the organic semiconductor ink, etc. The temperature during spin coating is not particularly limited, but is usually 100°C or lower, for example, 20 to 80°C.

The heating conditions for heat-drying the coating film are preferably at a temperature at which the solvent can be removed by drying and the components in the ink do not undergo thermal decomposition or thermal deterioration. Specifically, it may differ depending on the type of solvent used, the solid content concentration, etc., but it is preferably 50 to 250°C, more preferably 80 to 230°C, and particularly preferably 100 to 200°C. The time for drying the solvent is sufficient as long as the solvent can be fully removed and the components in the ink do not deteriorate. It will also vary depending on the type of solvent, solid content concentration, heating temperature, etc., but usually Perform within 1 to 60 minutes.

The film thickness of the photoelectric conversion layer of the present invention can be arbitrarily designed depending on the composition of the photoelectric conversion layer or the use of the organic photoelectric conversion element having the photoelectric conversion layer of the present invention. The film thickness of the photoelectric conversion layer is preferably thick in order to easily increase the efficiency of light absorption, and thin in order to prevent element output loss due to an increase in internal resistance. Therefore, the film thickness of the photoelectric conversion layer is usually set to 10 nm to 1 μm.

[Organic photoelectric conversion element] The organic photoelectric conversion element of the present invention is an element having the above-mentioned photoelectric conversion layer of the present invention.

The structure of the organic photoelectric conversion element of the present invention is not particularly limited as long as it has the photoelectric conversion layer of the present invention. For example, the same structure as the element disclosed in Japanese Patent Application Publication No. 2007-324587 can be mentioned. That is, for example, it may be a structure in which a transparent electrode, an electron transport layer, the photoelectric conversion layer of the present invention, a hole transport layer, and a metal electrode are sequentially laminated on a transparent substrate. Alternatively, a transparent electrode, an electron transport layer, and a metal electrode may be laminated in this order on a transparent substrate. The hole transport layer, the photoelectric conversion layer of the present invention, the electron transport layer, and the structure of the metal electrode. Furthermore, the organic photoelectric conversion element of the present invention may have layers other than these, or may not have two electrodes and layers other than the photoelectric conversion layer of the present invention.

FIG. 1 is a schematic cross-sectional view showing an example of the organic photoelectric conversion element of the present invention. The organic photoelectric conversion element 10 has in sequence a first electrode 11 as an upper electrode, a hole transport layer 12, a photoelectric conversion layer 13, an electron transport layer 14, and a second electrode 15 as a lower electrode (hereinafter, organic photoelectric conversion element may be referred to as The two electrodes of the conversion element, the first electrode 11 and the second electrode 15, are collectively referred to as "two electrodes"). In this example, the hole transport layer 12, the photoelectric conversion layer 13 and the electron transport layer 14 form the organic photoelectric film 20. Usually, a substrate is provided on the side of the first electrode 11 opposite to the hole transport layer 12 .

＜Photoelectric conversion layer＞ The photoelectric conversion layer is a layer that absorbs light and separates charges. The organic photoelectric conversion element of the present invention has the above-mentioned photoelectric conversion layer of the present invention.

＜Electrode＞ The electrodes (the first electrode and the second electrode) can be formed of any conductive material.

Examples of materials constituting the electrode include: platinum, gold, silver, aluminum, chromium, nickel, copper, titanium, magnesium, calcium, barium, sodium and other metals or their alloys; indium oxide or oxide Metal oxides such as tin, or their composite oxides (such as ITO, IZO); conductive polymers such as polyaniline, polypyrrole, polythiophene, and polyacetylene; hydrochloric acid, sulfuric acid, and sulfonic acid are added to the above conductive polymers Conductive polymers such as acids, Lewis acids such as FeCl ₃ , halogen atoms such as iodine, and metal atoms such as sodium and potassium; disperse conductive particles such as metal particles, carbon black, fullerene, and carbon nanotubes Conductive composite materials formed in a polymer binder matrix. The material constituting the electrode may be one type alone, or two or more types may be used in any combination and ratio.

At least one pair (2) electrodes are provided in the organic photoelectric conversion element, and a photoelectric conversion layer is provided between the pair of electrodes. At this time, it is preferable that at least one of the pair of electrodes is transparent (that is, it transmits light absorbed by the photoelectric conversion layer in order to generate electricity). Examples of materials for transparent electrodes include composite oxides such as indium tin oxide (ITO) and indium zinc oxide (IZO); metal thin films, and the like. There is no specific limit on the light transmittance when using a transparent electrode, but when considering the photoelectric conversion efficiency of the organic photoelectric conversion element, it is preferably 80% or more. Light transmittance can usually be measured using a spectrophotometer.

The electrode has the function of capturing holes and electrons generated in the photoelectric conversion layer. Therefore, as a constituent material of the electrode, it is preferable to use a constituent material suitable for capturing holes and electrons among the above-mentioned materials. Examples of materials suitable for the electrode for trapping holes include materials with a relatively high work function such as Au and ITO. As a material suitable for an electrode that captures electrons, a material with a relatively low work function such as Al can be cited.

The thickness of the electrode is not particularly limited and can be appropriately determined taking into account the material of the electrode, required conductivity, transparency, etc., but is usually set to 10 nm to 100 μm.

The formation method of the electrode is not limited. The electrodes can be formed by dry processes such as vacuum evaporation and sputtering. In addition, for example, it can also be formed by a wet process using conductive ink or the like. At this time, any conductive ink can be used. For example, conductive polymers, metal particle dispersions, etc. can be used. The electrode may have a laminated structure of two or more layers, and may also be subjected to surface treatment for improving characteristics (electrical characteristics, wetting characteristics, etc.).

＜Substrate＞ The organic photoelectric conversion element may also have a substrate to support two electrodes, a photoelectric conversion layer, and layers other than these. The substrate may be provided on either one of the first electrode side and the second electrode side, or may be provided on both sides, but is preferably provided on at least the first electrode side. Although the substrate can be made of any material, when light is incident from the substrate side, a material with higher transparency is preferred.

Examples of materials constituting the substrate include inorganic materials such as glass, sapphire, and titanium dioxide; polyethylene terephthalate, polyethylene naphthalate, polyether ethylene, polyimide, Nylon, polystyrene, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, fluororesin, vinyl chloride, polyethylene, cellulose, polyvinylidene chloride, aromatic polyamide, polyphenylene sulfide, polyaminomethyl Resins such as acid ester, polycarbonate, polyarylate, and polynorphene; paper materials such as paper and synthetic paper; stainless steel, titanium, aluminum and other metal composite materials with insulating coating or lamination on the surface. One type of material may be used alone as the constituent material of the substrate, or two or more types may be used in any combination and ratio.

The substrate can be one piece or a multi-layer structure of two or more pieces. In order to impart gas barrier properties or control surface conditions, other layers may be laminated on the substrate.

There are no restrictions on the structure, shape, and size of the substrate. As long as it can support components other than the substrate that constitute the organic photoelectric conversion element, any structure, shape, and size can be used and set arbitrarily. The thickness of the substrate can be arbitrarily designed depending on the use of the organic photoelectric conversion element, the material of the base material, the material of the layers of the element, etc. However, as a supporting member, in terms of excellent strength, it is preferably thicker, so that it can be reduced The size of the organic photoelectric conversion element is preferably thinner in order to keep the price low when using a substrate made of an expensive material. The substrate is preferably in the form of a film or plate with a film thickness usually ranging from 10 μm to 50 mm.

＜Hole transport layer＞ The hole transport layer is not necessary in the organic photoelectric conversion element, but by disposing the hole transport layer between the photoelectric conversion layer and the first electrode, the photoelectric conversion efficiency can be improved or dark current can be reduced.

The hole transport layer may use a known hole transport material. For example, hole-transporting polymers such as polytriarylamine compounds exemplified below can be used. In addition, for example, 2,7-bis(4-bromophenyl)-9,9-dihexylfluorene and 2-amino-9,9 described in Japanese Patent Application Laid-Open No. 2019-173032 can be used. -Dihexylfluorene, 4-(4-(1,1-bis(4'-bromo-[1,1'-biphenyl]-4-yl)ethyl)phenyl)-1,2-dihydrocyclo Polytriarylamine compound synthesized from but[a]naphthalene; composed of 4,4'-dibromobiphenyl, 2-amino-9,9-dihexylfluorene, 3-(1,2-dihydroxycyclobut[a] ] Naphthalene-4-yl)aniline is a polytriarylamine compound synthesized from 4,4'-dibromobiphenyl, 4-(3,5-dibromophenyl)-1,2-dihydrocyclobutane [a ]Naphthalene, polytriarylamine compounds synthesized from 2-amino-9,9-dihexylfluorene, etc. The hole transport material is not limited to these.

[Chemical 10]

[Chemical 11]

[Chemical 12]

The method of manufacturing the hole transport layer is not particularly limited, but it is preferably formed by a wet film-forming method using a hole transport polymer. When forming a hole transport layer by a wet film-forming method using a hole transport polymer, a hole transport layer forming composition containing a hole transport polymer and a solvent is usually used.

The solvent used here only needs to dissolve the hole-transporting polymer, and is usually used to dissolve more than 0.05% by mass, preferably more than 0.5% by mass, and more preferably more than 1% by mass of the hole-transporting polymer at room temperature. of solvent. The type of solvent is not particularly limited, but preferred examples include ether solvents, ester solvents, aromatic hydrocarbon solvents, and amide solvents.

Examples of the ether solvent include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, propylene glycol-1-monomethyl ether acetate (PGMEA), and 1,2-dimethoxy. Benzene, 1,3-dimethoxybenzene, anisole, phenethyl ether, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole , 2,4-dimethylanisole and other aromatic ethers.

Examples of the ester-based solvent include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate. Examples of aromatic hydrocarbon solvents include toluene, xylene, cyclohexylbenzene, 3-isopropylbiphenyl, 1,2,3,4-tetramethylbenzene, and 1,4-diisopropyl Benzene, cyclohexylbenzene, methylnaphthalene, etc. Examples of the amide-based solvent include N,N-dimethylformamide, N,N-dimethylacetamide, and the like. In addition to these, dimethyl styrene and the like can also be used.

The concentration of the hole transporting polymer in the composition for forming a hole transporting layer containing a hole transporting polymer is arbitrary, but in terms of uniformity of film thickness, it is preferably low so that it is not easy to conduct electricity. In terms of preventing defects in the hole transmission layer, it is preferably higher. The concentration of the hole transporting polymer in the hole transport layer forming composition is specifically preferably 0.01 mass% or more, more preferably 0.1 mass% or more, further preferably 0.5 mass% or more, and more preferably 70 mass % or less, more preferably 60 mass % or less, still more preferably 50 mass % or less.

The concentration of the solvent in the hole transport layer forming composition is usually 10 mass% or more, preferably 30 mass% or more, more preferably 50 mass% or more.

When a hole transport layer-forming composition is used to form a hole transport layer, the layer formed after applying the hole transport layer-forming composition is usually heated. The heating method is not particularly limited. The conditions for heating and drying are usually 100°C or higher, preferably 120°C or higher, more preferably 150°C or higher, usually 400°C or lower, preferably 350°C or lower, more preferably below 300℃. The heating time is usually 1 minute or more, preferably 24 hours or less. The heating method is not particularly limited, but methods such as placing the laminated body having the formed layers on a hot plate or heating in an oven can be used. For example, it can be performed under conditions such as heating at 120° C. or higher for 1 minute or longer on a hot plate.

The film thickness of the hole transport layer is preferably thicker in order to easily express the effect of reducing dark current by providing the hole transport layer as a blocking layer. For CMOS (CMOS) using organic photoelectric conversion elements Complementary Metal Oxide Semiconductor (Complementary Metal Oxide Semiconductor) image sensor is preferably thinner in terms of widening the incident angle of light and making it easy to thin the organic photoelectric conversion element. When the hole transport layer is provided, the film thickness is preferably 50 nm or more, more preferably 100 nm or more, and preferably 400 nm or less, and more preferably 350 nm or less.

The LUMO of the hole transport layer is preferably shallower than the LUMO of the n-type organic semiconductor of the photoelectric conversion layer in order to easily and effectively reduce dark current. Specifically, it is preferably shallower by 0.3 eV or more. More preferably, it is shallower than 0.5 eV, and still more preferably, it is shallower than 1.0 eV. Regarding the HOMO of the hole transport layer, in order to easily and efficiently transport the holes generated in the photoelectric conversion layer to the first electrode, the difference between the HOMO of the p-type organic semiconductor of the photoelectric conversion layer and that of the photoelectric conversion layer is preferably small. , specifically, the difference is preferably within 0.5 eV, more preferably within 0.3 eV.

＜Electron transport layer＞ The electron transport layer is not necessary in the organic photoelectric conversion element, but by disposing the electron transport layer between the photoelectric conversion layer and the second electrode, the photoelectric conversion efficiency can be improved or dark current can be reduced.

The electron transport layer contains a compound that can efficiently transport electrons generated in the photoelectric conversion layer to the second electrode. It is important to use a compound that has high electron injection efficiency from the photoelectric conversion layer and has high electron mobility and can efficiently transport the injected electrons as the electron transport compound contained in the electron transport layer. Therefore, the difference between the LUMO of the electron transport layer and the n-type semiconductor of the photoelectric conversion layer is preferably small. Specifically, the difference is preferably 1.5 eV or less, more preferably 1.0 eV. On the other hand, when dark current is reduced by providing an electron transport layer, the electron transport layer is preferably a deeper HOMO than the p-type semiconductor of the photoelectric conversion layer. Specifically, it is preferably a deeper HOMO of 0.3 eV. or above, more preferably 0.5 eV or more, further preferably 1.0 eV or more.

Examples of the electron-transporting compound used in the electron-transporting layer include metal complexes such as aluminum complexes of 8-hydroxyquinoline (Japanese Patent Laid-Open No. Sho 59-194393), 10-hydroxybenzo [h] Quinoline metal complexes, oxadiazole derivatives, distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzene Tetrazole metal complex, benzothiazole metal complex, triphenzimidazolylbenzene (US Patent No. 5645948), quinoline compound (Japanese Patent Application Laid-Open No. 6-207169), phenanthroline derivatives (Japanese Patent Application Laid-Open No. 5-331459), 2-tert-butyl-9,10-N,N'-dicyananthraquinonediimide, fullerene, n-type hydrogenated amorphous silicon carbide , n-type zinc sulfide, n-type zinc selenide, etc.

As a material for forming the electron transport layer, metal oxides such as titanium oxide, zinc oxide, tin oxide, and cerium oxide can also be used. In this case, as a method for manufacturing the electron transport layer, the following methods can be used: wet film formation and drying of metal oxide nanoparticles to form a metal oxide layer; or wet film formation of a metal oxide precursor. Formula film formation and heating conversion.

The film thickness of the electron transport layer is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less.

The electron transport layer can be formed by a wet film forming method or a vacuum evaporation method, and is usually formed by a vacuum evaporation method.

＜Other layers＞ The organic photoelectric conversion element of the present invention may be provided with layers other than the above-mentioned electrodes, layers, etc., as long as the effects of the present invention are not significantly impaired.

For example, in order to reduce the influence of external environment such as outside air, the organic photoelectric conversion element of the present invention may be provided with a protective film so as to cover the photoelectric conversion layer part and further cover the part including the electrode. The protective layer may include, for example, polymer films such as styrene resin, epoxy resin, acrylic resin, polyurethane, polyimide, polyvinyl alcohol, polyvinylidene fluoride, polyethylene polyvinyl alcohol copolymer, etc. ; Inorganic oxide films or nitride films such as silicon oxide, silicon nitride, aluminum oxide, etc.; or these laminated films, etc.

The formation method of the above protective film is not limited. For example, when the protective film is made into a polymer film, a formation method is carried out by coating and drying a polymer solution; a formation method is a formation method of coating or vapor-depositing a monomer and polymerizing it, etc. In addition, when forming a polymer film, a cross-linking treatment may be further performed, or a multilayer film may be formed. When the protective film is made into an inorganic film such as an inorganic oxide film or a nitride film, it can be formed by, for example, the following methods: forming methods using vacuum processes such as sputtering and evaporation; using sol-gel methods. It is the formation method of the representative solution process.

In order for the electrode to efficiently capture the charges generated in the photoelectric conversion layer, a charge injection layer may be provided between the first electrode and the hole transport layer, or between the electron transport layer and the second electrode.

For example, the organic photoelectric conversion element of the present invention may be provided with a filter that does not transmit ultraviolet rays on the incident side of the light. Since ultraviolet rays generally promote the deterioration of organic photoelectric conversion elements, blocking the ultraviolet rays can extend the life of the organic photoelectric conversion elements.

＜Manufacturing method of organic photoelectric conversion element＞ The organic photoelectric conversion element of the present invention can be produced by laminating each layer or member in this order: a first electrode, a photoelectric conversion layer and other constituent layers, and a second electrode. In the case of the above example, it can usually be manufactured by sequentially stacking a first electrode, a hole transport layer, a photoelectric conversion layer, and a second electrode on a substrate through the above method. In addition, an optional electron transport layer or the like is formed between these layers.

＜Uses of organic photoelectric conversion elements＞ The organic photoelectric conversion element of the present invention can be suitably used in a photo sensor, an imaging element, etc. In this case, the structures of the photo sensor and the imaging element only need to use known structures. [Example]

Hereinafter, the present invention will be described in more detail through examples. The scope of the present invention is not limited by the following examples.

[Example 1] <Preparation of organic semiconductor ink> A mixed solvent of xylene (manufactured by Sigma-Aldrich Co., Ltd.) and 1,2,4-trimethylbenzene (manufactured by Kanto Chemical Co., Ltd.) (volume ratio 1:1) 1 The following p-type organic semiconductor 8 mg, n-type organic semiconductor 16 mg, and 1,2,3,4-tetraphenylnaphthalene (manufactured by Sigma-Aldrich, HOMO: -6.5 eV, LUMO: -2.7 eV) were added to mL. )8 mg to prepare a solution for organic semiconductor ink. p-type organic semiconductor: p-type organic semiconductor represented by the above-mentioned formula (II) (manufactured by 1-Material Co., Ltd., weight average molecular weight 240000, LUMO: -3.5 eV) n-type organic semiconductor: in the above-mentioned formula (I), A= ^{Carbon atoms X 1 - _ _ _} Non-fullerene n-type organic semiconductor (HOMO: -5.5 eV)

The solution for organic semiconductor ink was heated and stirred on a heating stirrer set to 100°C for 3 hours, and then left to stand at room temperature (25°C) for 3 hours, and then filtered with a 5 μm polytetrafluoroethylene filter. Furthermore, the solution for organic semiconductor ink was left to stand at room temperature (25° C.) overnight to prepare an organic semiconductor ink.

＜Manufacturing of photoelectric conversion layer＞ Use an ultraviolet ozone cleaner (NL-UV253, manufactured by Nippon Laser Electronics Co., Ltd.) to perform a 10-minute ultraviolet ozone treatment on the surface of the ITO substrate with a transparent conductive film of indium tin oxide (ITO) formed as an electrode pattern on the glass substrate. Finally, the hole transport layer is formed as follows.

Dissolve 60 mg of the polytriarylamine compound (hole-transporting polymer) represented by the following formula (1) in 1 mL of anisole to prepare a composition for forming a hole-transporting layer. The composition was spin-coated on the electrode surface of the ITO substrate at a rotation speed of 1000 rpm for 60 seconds, and then heated and dried at 240°C for 30 minutes to form a hole transport layer with a film thickness of 300 nm.

[Chemical 13]

Use the organic semiconductor ink prepared before, spin-coat it on the hole transport layer at a speed of 1000 rpm for 60 seconds, and then heat and dry it at 120°C for 10 minutes to produce a photoelectric conversion layer with a film thickness of 180 nm.

[Example 2] Except using 24 mg of 1,2,3,4-tetraphenylnaphthalene, an organic semiconductor ink was prepared in the same manner as in Example 1, and the photoelectric conversion layer was produced using the organic semiconductor ink.

[Comparative example 1] Except that 1,2,3,4-tetraphenylnaphthalene was not used, an organic semiconductor ink was prepared in the same manner as in Example 1, and the photoelectric conversion layer was produced using the organic semiconductor ink.

[Comparative example 2] An organic semiconductor ink was prepared in the same manner as in Example 1 except that pyrene (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 1,2,3,4-tetraphenylnaphthalene, and the photoelectric conversion layer was produced using the organic semiconductor ink.

[Comparative example 3] An organic semiconductor ink was prepared in the same manner as in Example 2 except that pyrene (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 1,2,3,4-tetraphenylnaphthalene, and a photoelectric conversion layer was produced using the organic semiconductor ink.

[Comparative example 4] An organic semiconductor ink was prepared in the same manner as in Example 1 except that anthracene (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 1,2,3,4-tetraphenylnaphthalene, and a photoelectric conversion layer was produced using the organic semiconductor ink.

[Comparative example 5] An organic semiconductor ink was prepared in the same manner as in Example 2 except that anthracene (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 1,2,3,4-tetraphenylnaphthalene, and a photoelectric conversion layer was produced using the organic semiconductor ink.

[Comparative example 6] Except using triptycene (manufactured by Tokyo Chemical Industry Co., Ltd.) instead of 1,2,3,4-tetraphenylnaphthalene, an organic semiconductor ink was prepared in the same manner as in Example 1, and the photoelectric conversion layer was produced using the organic semiconductor ink. .

[Comparative Example 7] Except using triptycene (manufactured by Tokyo Chemical Industry Co., Ltd.) instead of 1,2,3,4-tetraphenylnaphthalene, an organic semiconductor ink was prepared in the same manner as in Example 2, and a photoelectric conversion layer was produced using the organic semiconductor ink. .

[Comparative example 8] An organic semiconductor ink was prepared in the same manner as in Example 1, except that 9,10-diphenylanthracene (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 1,2,3,4-tetraphenylnaphthalene. The ink makes the photoelectric conversion layer.

[Comparative Example 9] An organic semiconductor ink was prepared in the same manner as in Example 2, except that 9,10-diphenylanthracene (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 1,2,3,4-tetraphenylnaphthalene. The ink makes the photoelectric conversion layer.

[Comparative Example 10] An organic semiconductor was prepared in the same manner as in Example 1, except that 5,6,11,12-tetraphenyl fused tetraphenyl (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 1,2,3,4-tetraphenylnaphthalene. Ink, use this organic semiconductor ink to make a photoelectric conversion layer.

[Comparative Example 11] An organic semiconductor was prepared in the same manner as in Example 2, except that 55,6,11,12-tetraphenyl fused tetraphenyl (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 1,2,3,4-tetraphenylnaphthalene. Ink, use this organic semiconductor ink to make a photoelectric conversion layer.

[Evaluation of film quality of photoelectric conversion layer] Use the optical microscope function of the Keyence laser microscope VK-X200 to observe the film quality of the photoelectric conversion layers produced in Examples 1 and 2 and Comparative Examples 1 to 11 at a magnification of 150 times. Moreover, after observation, it heated at 200 degreeC for 50 minutes in a nitrogen atmosphere, and then observed again in the same manner.

Table 1 shows the observation results of film quality before and after heating. Moreover, each optical microscope photograph is shown in FIGS. 2-8.

[Table 1] compatibilizer Relative to the mass ratio of P-type semiconductor membranous before heating After heating Example 1 1,2,3,4-tetraphenylnaphthalene 1.0 Uniform Uniform Example 2 1,2,3,4-tetraphenylnaphthalene 3.0 Uniform Uniform Comparative example 1 without - Uniform Spots about 1-5 μm Comparative example 2 Pyrene 1.0 Uniform Precipitation crystallization Comparative example 3 Pyrene 3.0 Precipitation crystallization Precipitation crystallization Comparative example 4 anthracene 1.0 Precipitation crystallization Precipitation crystallization Comparative example 5 anthracene 3.0 Precipitation crystallization Precipitation crystallization Comparative example 6 triptycene 1.0 Precipitation crystallization Spots about 1-5 μm Comparative example 7 triptycene 3.0 Precipitation crystallization Spots about 1-5 μm Comparative example 8 9,10-Diphenylanthracene 1.0 Precipitation crystallization Precipitation crystallization Comparative example 9 9,10-Diphenylanthracene 3.0 Precipitation crystallization Precipitation crystallization Comparative example 10 5,6,11,12-tetraphenylcondensed tetraphenyl 1.0 Uniform Spots about 10 μm Comparative example 11 5,6,11,12-tetraphenylcondensed tetraphenyl 3.0 Precipitation crystallization Precipitation crystallization

[Inspection] By comparing Examples 1 and 2 with Comparative Examples 1 to 11, it was confirmed that by using the compatibilizer of the present invention, it is possible to obtain a p-type organic semiconductor that is uniformly contained and is less susceptible to phase separation even with the passage of time or heating. and organic films of n-type organic semiconductors. Specifically, when only a p-type organic semiconductor and an n-type organic semiconductor were mixed like Comparative Example 1, spots of approximately 1 to 5 μm were observed after heating. It is thought that this is caused by the phase separation of p-type organic semiconductor and n-type organic semiconductor. In contrast, in Examples 1 and 2, such phase separation was not observed, suggesting that 1,2,3,4-tetraphenylnaphthalene functions as a compatibilizer.

In Comparative Examples 2 to 7, conjugated compounds similar to 1,2,3,4-tetraphenylnaphthalene were used, and it was confirmed that these compounds precipitated crystals before and after heating. Pyrene and anthracene are compounds similar to polycyclic aromatic hydrocarbons, but they have a simple two-dimensional planar structure, so it is easy to produce orderly crystals. Regarding triptycene, since each of the three benzene ring skeletons does not exist in the same Although it has a three-dimensional structure on a plane, it does not have a polycyclic aromatic hydrocarbon partial skeleton, so it is considered to have low compatibility with p-type organic semiconductors and n-type organic semiconductors.

Comparative Examples 8 to 11 are comparative examples using 9,10-diphenylanthracene and 5,6,11,12-tetraphenylcondensed tetraphenyl. The above 9,10-diphenylanthracene and 5,6,11, 12-Tetraphenylcondensed tetraphenyl is a conjugated compound similar to 1,2,3,4-tetraphenylnaphthalene, and is a compound in which the substituents R are in positions that are not adjacent to each other. Since the substituents R of these compatibilizers are in positions that are not adjacent to each other, it is considered that compared with 1,2,3,4-tetraphenylnaphthalene, it is easier to form a two-dimensional planar structure in the film, that is, it is easier to generate crystals. , unable to fully obtain compatibility with p-type organic semiconductors and n-type organic semiconductors.

It is estimated from the above results that by using the compatibilizer of the present invention, it has solubility in each of the p-type organic semiconductor and the n-type organic semiconductor, and also does not cause self-aggregation or change due to heating or time-dependent changes. Crystal formation can suppress the increase in phase separation size of the BHJ structure.

Although the present invention has been described in detail using specific aspects, it will be apparent to those skilled in the art that various changes can be made without departing from the intention and scope of the present invention. This application is based on Japanese Patent Application 2022-023979 filed on February 18, 2022, the entire content of which is incorporated by reference.

10: Organic photoelectric conversion element 11: 1st electrode 12: Hole transport layer 13: Photoelectric conversion layer 14:Electron transport layer 15: 2nd electrode 20: Organic photoelectric film

FIG. 1 is a schematic cross-sectional view showing an example of the embodiment of the organic photoelectric conversion element of the present invention. Figure 2 is an optical microscope photograph of the film surface of the photoelectric conversion layer produced in Examples 1 and 2 before and after heating. 3 is an optical microscope photograph of the film surface of the photoelectric conversion layer produced in Comparative Example 1 before and after heating. Figure 4 is an optical microscope photograph of the film surface of the photoelectric conversion layer produced in Comparative Example 2 and Comparative Example 3 before and after heating. Figure 5 is an optical microscope photograph of the film surface of the photoelectric conversion layer produced in Comparative Example 4 and Comparative Example 5 before and after heating. 6 is an optical microscope photograph of the film surface of the photoelectric conversion layer produced in Comparative Example 6 and Comparative Example 7 before and after heating. 7 is an optical microscope photograph of the film surface of the photoelectric conversion layer produced in Comparative Example 8 and Comparative Example 9 before and after heating. 8 is an optical microscope photograph of the film surface of the photoelectric conversion layer produced in Comparative Example 10 and Comparative Example 11 before and after heating.

Claims (20)

An organic semiconductor ink, characterized by: containing p-type organic semiconductor, n-type organic semiconductor, compatibilizer and solvent, and The compatibilizer is the following organic compound: having 2 to 5 condensed rings A of an aromatic hydrocarbon ring with two or more adjacent substituents R as the main skeleton, At least one of the substituents R is a valence group of the aromatic hydrocarbon ring B. The aromatic hydrocarbon ring B is a single aromatic hydrocarbon ring, or the number of condensed rings is the same as or less than that of the condensed ring A. 2 to 4 condensed rings of hydrocarbon rings, The condensed ring A and the aromatic hydrocarbon ring B do not exist on the same plane. An organic semiconductor ink containing p-type organic semiconductor, n-type organic semiconductor, compatibilizer and solvent, and The compatibilizer has a main skeleton of 2 to 5 condensed rings A of an aromatic hydrocarbon ring with two or more substituents R adjacent to each other. The substituent R is a monovalent group of the aromatic hydrocarbon ring B', which is a single aromatic hydrocarbon ring or 2 to 4 condensed rings of aromatic hydrocarbon rings. Such as the organic semiconductor ink of claim 2, wherein the substituent R is a valent group of an aromatic hydrocarbon ring B, and the aromatic hydrocarbon ring B is an aromatic hydrocarbon ring with the same number of condensed rings as or less than that of the condensed ring A. 2 to 4 condensed rings. The organic semiconductor ink according to any one of claims 1 to 3, wherein all the above-mentioned R's are monovalent groups of aromatic hydrocarbon rings. The organic semiconductor ink of claim 4, wherein all of the above R are phenyl groups. The organic semiconductor ink of claim 5, wherein the compatibilizer is selected from the group consisting of 1,2,3,4-tetraphenylnaphthalene and 1-methyl-3,4-diphenylnaphthalene. The organic semiconductor ink of any one of claims 1 to 6, wherein the p-type organic semiconductor and n-type organic semiconductor do not have cross-linking groups. The organic semiconductor ink according to any one of claims 1 to 7, wherein the p-type organic semiconductor is a polymer compound. The organic semiconductor ink of claim 8, wherein the p-type organic semiconductor is a polymer compound with a weight average molecular weight of 50,000 to 400,000. The organic semiconductor ink of claim 8 or 9, wherein the polymer compound is a polymer compound represented by the following formula (II): [Chemical 1] (In formula (II), n is a positive number). The organic semiconductor ink of any one of claims 1 to 10, wherein the n-type organic semiconductor is a non-fullerene-type semiconductor. The organic semiconductor ink of claim 11, wherein the non-fullerene semiconductor is at least any one of a compound represented by the following formula (I) and a polymer of a compound represented by the following formula (I): [Chemicalization 2] (In formula (I), A represents an atom selected from Group 14 of the periodic table, X ¹ to X ⁴ each independently represents a hydrogen atom or a halogen atom, R ^1a and R ^1b each independently represents a chain alkyl group, R ² ~R ⁵ each independently represents a chain alkyl group, a chain alkoxy group, a chain thioalkyl group, or a hydrogen atom). The organic semiconductor ink according to any one of claims 1 to 12, wherein the content ratio (mass ratio) of the compatibilizer to the p-type organic semiconductor is 0.1 or more and 10.0 or less. The organic semiconductor ink according to any one of claims 1 to 13, wherein the solvent is xylene. An organic film, characterized in that: it contains a p-type organic semiconductor, an n-type organic semiconductor and an organic compound, and The organic compound has a main skeleton of 2 to 5 condensed rings A of aromatic hydrocarbon rings with two or more substituents R adjacent to each other. At least one of the substituents R is a valence group of the aromatic hydrocarbon ring B. The aromatic hydrocarbon ring B is a single aromatic hydrocarbon ring, or the number of condensed rings is the same as or less than that of the condensed ring A. 2 to 4 condensed rings of hydrocarbon rings, The condensed ring A and the aromatic hydrocarbon ring B do not exist on the same plane. An organic film containing a p-type organic semiconductor, an n-type organic semiconductor and an organic compound, and The organic compound has a main skeleton of 2 to 5 condensed rings A of aromatic hydrocarbon rings with two or more substituents R adjacent to each other. The substituent R is a monovalent group of the aromatic hydrocarbon ring B', which is a single aromatic hydrocarbon ring or 2 to 4 condensed rings of aromatic hydrocarbon rings. The organic film of claim 16, wherein the substituent R is a valent group of an aromatic hydrocarbon ring B, and the number of condensed rings of the aromatic hydrocarbon ring B is the same as or less than that of the condensed ring A. 2 to 4 condensed rings. A photoelectric conversion layer comprising the organic film according to any one of claims 15 to 17. A method for manufacturing a photoelectric conversion layer, which has the step of applying the organic semiconductor ink according to any one of claims 1 to 14. An organic photoelectric conversion element containing a photoelectric conversion layer including the organic film according to any one of claims 15 to 17.