JP2002129045A - Photoelectric conversion agent and relational technique thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a photoelectric conversion agent including an azine-based compound, partially substituted with N-aryl, effectively usable as a photoactive material in an element essentially using a photoelectric conversion action of material, that is, in a charge-generating layer of a photosensitive body of an electrophotography, an optical current-generating layer of an organic solar cell, an optical sensor, an optical switching element and the like. SOLUTION: The photoelectric conversion agent composed of the azine-based compound, partially substituted with N-aryl, expressed by formula (I), the photosensitive body of the electrophotography having the agent in the charge- generating layer, and the organic solar cell having the agent in the optical current layer, are provided. In formula (I), R1 and R2 denote each hydrogen or a halogen atom, R3 and R4 denote each an aryl group that can has a substituting group, R5 and R6 denote each hydrogen, alkyl, aralkyl, aryl, arylamino and aryloxy group, or the halogen atom, and (k), (m) and (n) denote each a positive integer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charge generation layer of an electrophotographic photosensitive member, a photocurrent generation layer of an organic solar cell, an optical sensor, an optical switching element, and the like. The present invention relates to a novel photoelectric conversion agent and a photoelectric conversion method useful as a photoelectric conversion material that can be effectively used as a photoactive substance, and to an electrophotographic photoreceptor and an organic solar cell using the photoelectric conversion agent.

[0002]

2. Description of the Related Art A large number of photoelectric conversion agents (materials) have been known so far. For example, Se and its alloys, Te and its alloys, C
Inorganic materials such as dS and Si are well known as having photosensitivity near visible light. However, many of these have serious problems not only in toxicity but also in practical use, such as being very expensive and poor in workability.

On the other hand, in order to overcome the above-mentioned problems of inorganic materials, organic compounds having a photoelectric conversion action (organic photoelectric conversion agents) have been developed. Organic dyes and pigments such as azo, perylene and phthalocyanine are well known as organic photoelectric conversion agents (materials). Among them, compounds other than phthalocyanines have insufficient stability and fastness. . Many phthalocyanine compounds are stable and robust and are promising, but have a problem in purification difficulty.

In recent years, in an image forming apparatus such as a copying machine or a printer to which the electrophotographic technique is applied, an organic photoreceptor having a sensitivity in a wavelength region of a light source used in such an apparatus is often used. As such an organic photoreceptor,
A single-layer photoreceptor having a single-layer type photosensitive layer in which a charge generation material and a charge transport material are dispersed in a thin film made of an appropriate binder resin,
2. Description of the Related Art A stacked photoconductor in which a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material are stacked is known.

A charge generation material which is one of the photoelectric conversion materials is 800 nm which is a transmission wavelength range of a semiconductor laser.
Attention has been paid to organic photoconductive substances having sensitivity before and after. Many organic photoconductors (OPCs) containing such an organic photoconductive substance as an active ingredient have been proposed. For example, an organic photoconductor using a phthalocyanine-based compound as a charge generating material has been put to practical use.

[0006] A photoelectric conversion agent is also used for a photocurrent generating layer of an organic solar cell. For example, The Chemical Society of Japan, 199
0, (9), p. 962-967 reports a study on an organic laminated solar cell using a phthalocyanine and a perylene derivative. The Chemical Society of Japan, 1992, (1
0), p. 1154-1161, phthalocyanine-
The relationship between the photoelectric conversion characteristics and the chemical structure of the dye in perylene derivative organic stacked solar cells has been reported.

The present invention has been made in view of the above-mentioned problems in the prior art, and has as its object to exhibit an excellent photoelectric conversion effect, and to improve workability, stability, and the like.
And a photoelectric conversion agent comprising an azine-based compound which has good robustness, is relatively easy to purify, and can be obtained at relatively low cost, a photoelectric conversion method using the azine-based compound, and the photoelectric conversion agent is contained. An object of the present invention is to provide an electrophotographic photosensitive member and an organic solar cell.

A technique using an azine compound (eg, a nigrosine dye) for an electrophotographic photoreceptor is disclosed in
As described in JP-A-8-9147, the nigrosine dye used here performs a charge holding function in a charge holding layer provided at the interface between the inorganic photosensitive layer and the insulating layer. It is not related to the conversion action. JP-A-55-50247 describes that a nigrosine dye is used as a component that highly absorbs infrared rays in at least one of the constituent elements of the electrostatic recording medium. In this case, the nigrosine dye is used as a material for improving the static elimination effect by infrared light, and is not related to the photoelectric conversion action.

Some of the azine compounds in the present invention are known compounds. J. Freita
g, et al. , Wissenschaftlich
e Zeitshift der Technish
en Universitagt Dressen 2
7 (1978) Heft 5,915. O .; N. W
itt, Chem. Ber. , 20, 1538 (18
87); Fischer, E .; Hepp, Che
m. Ber. , 23, 2789 (1890). However, these documents have no description regarding the photoelectric conversion agent (material).

[0010]

Means for Solving the Problems The present inventors have found that an azine compound represented by the following formula (I) has an absorption spectrum extending in the near infrared region and has a large photoelectric conversion upon irradiation with white light. The present inventors have found that they exert an effect, and have completed the present invention based on the findings.

The photoelectric conversion agent of the present invention comprises a partially N-aryl-substituted azine compound represented by the following formula (I).
The photoelectric conversion method of the present invention is characterized by using a partially N-aryl-substituted azine-based compound represented by the following formula (I).

[0012]

Embedded image .... Formula (I)

[0013] In the formula (I), ^{R 1} and ^{R 2} are, independently of each other, represent a hydrogen atom or a halogen atom, ^{R 3} and R
⁴ independently represent an aryl group which may have a substituent; R ⁵ and R ⁶ independently represent a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, an arylamino group, an aryl group; It represents an oxy group or a halogen atom, and k, m, and n each represent a positive integer. ]

The above partially N-aryl-substituted azine compound is preferably an extract from a nigrosine compound.

The partially N-aryl-substituted azine-based compound has an X-ray diffraction spectrum by CuKα ray of 9.6 °, 17.2 °, 2 ° of Bragg angle (2θ ± 0.2 °).
0.2 ゜, 21.3 ゜, 26.2 ゜, 27.0 ゜, 2
It preferably has a crystal modification showing strong diffraction peaks at 7.8 ° and 29.6 °.

Next, the electrophotographic photoreceptor of the present invention contains the above-mentioned photoelectric conversion agent of the present invention in a charge generation layer.

The organic solar cell of the present invention contains a photoelectric conversion agent in the photocurrent generating layer.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, R ¹ and R ² in the above formula (I) representing the azine compound (hereinafter sometimes referred to as an N-aryl-substituted azine compound) in the present invention are independently of each other. (That is, they may be the same or different), a hydrogen atom, or a halogen atom such as chlorine, bromine, iodine, and fluorine. Of these, a hydrogen atom and a chlorine atom are preferred.

R ³ and R ⁴ in the formula (I) each independently represent a substituted or unsubstituted group such as a phenyl group, a substituted phenyl group, a naphthyl group or a substituted naphthyl group. Represents an aryl group. Examples of substituents on these phenyl and naphthyl groups include a methyl group,
Examples include an alkyl group such as an ethyl group, an alkoxy group such as a methoxy group and an ethoxy group, and a halogen atom such as chlorine, bromine, iodine, and fluorine.

R ⁵ and R ⁶ in the formula (I) each independently represent a hydrogen atom; a linear or branched alkyl group such as a methyl group, an ethyl group, an isopropyl group, a butyl group and an octyl group (for example, An aralkyl group such as a benzyl group, an α, α-dimethylbenzyl group, or a benzyl group having a substituent (eg, a methyl group, a methoxy group, chlorine, etc.); a phenyl group or a substituent Substituents (for example, an alkyl group such as a methyl group and an ethyl group, an alkoxy group such as a methoxy group and an ethoxy group, a halogen atom such as chlorine, bromine, iodine, and fluorine) such as a phenyl group, a naphthyl group, and a naphthyl group having a substituent. Or an unsubstituted aryl group; an arylamino group such as a phenylamino group;
An aryloxy group such as a phenoxy group or a naphthoxy group; or a halogen atom. Among them, particularly preferred is
A phenylamino group and a phenoxy group.

In the formula (I), n is preferably an integer of 1 to 3, and k and m are each preferably 1 or 2.

Next, preferred examples of the N-aryl-substituted azine-based compound represented by the above formula (I) are shown below, but the present invention is not limited thereto.

[0023]

Embedded image (Compound 1)

[0024]

Embedded image (Compound 2)

[0025]

Embedded image (Compound 3)

[0026]

Embedded image (Compound 4)

[0027]

Embedded image (Compound 5)

[0028]

Embedded image (Compound 6)

[0029]

Embedded image (Compound 7)

[0030]

Embedded image (Compound 8)

[0031]

Embedded image (Compound 9)

[0032]

Embedded image (Compound 10)

The chemical structure of the above compound example is ¹ H-NM
Confirmed by R, IR and double focusing mass spectrometry.

¹ H-NMR of compound 1 (CDCl ₃ , 3
00 MHz) is 5.47 (s, 2H), 6.12
(D, 2H), 6.5 to 7.8 (m, 16H). The mass measured by double focusing mass spectrometry was 43
6.1661, which was in agreement with the calculated value (436.1688).

Compound 5 has a mass of 527.2142 measured by double-focusing mass spectrometry, and the calculated value (527.
2110). Also, by IR analysis, 3200cm
^{At -1} , absorption of -NH- was confirmed.

Compound 6 has a mass of 527.2109 measured by double-focusing mass spectrometry, and the calculated value (527.
2110). 3200cm by IR analysis
^{At -1} , absorption of -NH- was confirmed.

Many of the azine compounds represented by the formula (I) are soluble in general organic solvents, and are easy to handle such as purification and coating, and are excellent in practicality.

Some of the azine compounds represented by the formula (I) exhibit many crystal modifications. For example, among the compounds exemplified in the present specification, several crystal forms were found by X-ray diffraction analysis, and it was found that the effect of photoelectric conversion differs depending on the crystal forms (specific crystal modifications). One of the findings of the present inventors is that CuKα
X-ray diffraction (XRD) spectrum by X-rays showed Bragg angles (2θ ± 0.2 °) of 9.6 °, 17.2 °, 20.2 °,
It is a partially N-aryl-substituted azine-based compound having a crystal modification showing strong diffraction peaks at 21.3, 26.2, 27.0, 27.8, and 29.6 (see Examples).

The photoelectric conversion agent comprising the azine-based compound represented by the formula (I) is used as an organic photoconductive material in an electrophotographic photosensitive member widely used in a copying machine or the like to which electrophotographic technology is applied. be able to. An electrophotographic organic photoreceptor comprising at least one azine-based compound represented by the formula (I) (for example, Compound 1 of the present invention) and a resin has a photosensitive layer comprising a charge generation layer (CGL) and a charge transport layer. (CT
L) and a single layer type. However, in order to effectively exhibit the electrical characteristics and photosensitive characteristics of the crystal modification of the N-aryl-substituted azine-based compound of the formula (I), the generated charges are less likely to be captured, and each layer has its function. It is preferable to apply the present invention to a function-separated type photoconductor having a two-layer structure, in which charges are efficiently transported to the photoconductor surface without hindrance.

Next, an example in which the N-aryl-substituted azine-based compound represented by the formula (I) is used for a layer that generates electric charges by photoelectric conversion will be described.

Such a function-separated type photoreceptor is, for example,
It can be formed by laminating a charge generation layer and a charge transport layer in a thin film on a conductive support. As the base material of the conductive support, a metal such as aluminum or nickel, a metal-deposited film, or the like can be used. The form of the base material of the conductive support may be a drum shape, a sheet shape, a belt shape, or the like.

In application to an organic photoreceptor for electrophotography, for example, first, a charge generation layer containing the N-aryl-substituted azine compound [photoelectric conversion agent] of the present invention as a charge generation material (CG material) is electrically supported. Formed on the body as a thin film. In this case, the charge generation layer can be formed, for example, by depositing an N-aryl-substituted azine compound of the formula (I) on a conductive support to form a thin film, but by dissolving a binder resin in a solvent. It is more common to form a coating solution in which an N-aryl-substituted azine compound of the formula (I) is dispersed in a solution as a charge generating material and apply the coating solution on a support.

As a method for dispersing the N-aryl-substituted azine compound (CG material) of the formula (I) in the above solution to prepare a coating solution, a usual dispersing method using a ball mill, a sand mill, a paint shaker or the like is employed. be able to.
The means for applying the charge generation layer to the support is not particularly limited, and for example, a bar coater, a dip coater, a spin coater, a roller coater or the like can be used as appropriate. The drying for obtaining the charge generation layer by drying the coating solution applied to the support is, for example, 30 to 20 days.
It can be performed at a temperature of 0 ° C. for 5 minutes to 2 hours under blowing or without blowing (stationary state).

The solvent for preparing the coating solution is not particularly limited as long as it can dissolve the binder resin used as required. For example, alcohol solvents such as methanol, ethanol, isopropanol and butanol; aromatic solvents such as toluene, xylene and tetralin; halogen solvents such as dichloromethane, chloroform, trichloroethylene and carbon tetrachloride; ethyl acetate and acetic acid Ester solvents such as propyl; ether solvents such as ethylene glycol monoethyl ether, dioxane, and tetrahydrofuran; dimethylformamide, dimethyl sulfoxide and the like.

The binder resin can be selected from various insulating synthetic resins. Preferred resins include condensation resins such as polycarbonate, polyester, polyamide, and polyarylate; polystyrene, polyacrylate, styrene-acrylic copolymer, polyacrylamide, polymethacrylate, polyvinyl butyral, polyvinyl alcohol, polyacrylonitrile, and polyacryl-. Addition polymers such as butadiene copolymer, polyvinyl chloride, and vinyl chloride-vinyl acetate copolymer; organic photoconductive resins such as poly-N-vinyl carbazole and polyvinyl anthracene;
Polysulfone, polyether sulfone, silicone resin,
Epoxy resins, urethane resins and the like can be mentioned.

The amount of the binder resin used in the charge generation layer is preferably generally 0.1 to 3 weight ratio to the charge generation material. If the ratio is larger than 3 weight ratio, the charge generation material concentration in the charge generation layer may be low, and the light sensitivity may be deteriorated. The thickness of the charge generation layer is generally 10 μm or less, and preferably 0.05 to 5.0 μm.

Next, a charge transport layer containing a charge transport material is formed on the charge generation layer. This charge transport layer can be formed by forming a layer containing a charge transport material in a thin film on the charge generation layer in the same manner as the charge generation layer. That is, for example, a charge transporting layer can be formed by dissolving a charge transporting material in a solvent together with a binder resin as required, uniformly applying the solution on the charge generating layer, and then drying it.

Examples of the charge transport material (CT material) include oxazole derivatives, oxadiazole derivatives, pyrazoline derivatives, hydrazone derivatives, hydrazine derivatives, triazine derivatives, quinazoline derivatives, triarylamine compounds, styryl compounds, and styryltri compounds. Examples include phenylamine-based compounds, butadiene-based compounds, carbazole-based compounds, and benzofuran derivatives (compounds).

As the binder resin and the solvent for forming the charge transport layer, the same ones as those used for the charge generation layer can be used.

The amount of the binder resin used in the charge transport layer is as follows:
The weight ratio is preferably 0.1 to 5 relative to the charge transporting material. If the ratio is more than 5% by weight, the concentration of the charge transporting material in the charge transporting layer becomes small, and the light sensitivity may be deteriorated. The thickness of the charge generation layer is generally 100 μm
And the thickness is preferably 5 to 50 μm.

The photoconductive material containing the photoelectric conversion agent (material) of the present invention can be prepared, for example, as described above, and when applied to the charge generation layer of an electrophotographic photoreceptor, the chargeability and half-exposure Good mass sensitivity, low residual potential, and high durability (sensitivity durability, potential durability).

The photoelectric conversion agent of the present invention can also be used for a photocurrent generation layer of an organic solar cell. For example, a thin film composed of an N-aryl-substituted azine-based compound represented by the formula (I) or a thin film composed of an N-aryl-substituted azine-based compound represented by the formula (I) and a binder resin is formed on an ITO transparent electrode. A thin film made of a perylene derivative (for example, N, N'-diphenyl-3,4,9,10-perylenetetracarboxylic acid diimide [PTC]) is provided by a vacuum deposition method or a coating method, and is further provided thereon by a similar method. The heterojunction type photoelectric conversion element provided with a gold electrode has a significant photocurrent observed by white light irradiation.

[0053]

According to the photoelectric conversion agent and the photoelectric conversion method of the present invention, the azine compound used exhibits an excellent photoelectric conversion effect, and is particularly useful as a charge generation material for an electrophotographic photoreceptor and has a residual potential. O with small and half sensitivity
While exhibiting PC properties, it has good processability, stability, and robustness, is relatively easy to purify, and can be obtained at a relatively low cost.
It can be effectively used in an element that essentially uses a photoelectric conversion action, such as a photocurrent generation layer of an organic solar cell, an optical sensor, an optical switching element, and the like.

[0054]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. still,
The X-ray diffraction spectrum by CuKα ray was measured using an automatic X-ray diffraction system “MXP18” manufactured by Max Science.

Compound 1 was obtained from O.D. Fischer, E .; H
epp, Chem. Ber. , 23, 2789 (18
90). Compound 1 can be synthesized or extracted from a nigrosine dye as described below.

[0056]Method for extracting compound 1  The azine-based compound 1 is a nigrosine-based EX
Tolue, a trade name of nigrosine dye manufactured by Nintendo Chemical Industry Co., Ltd.
Precipitates from impurities or ethyl acetate dissolved components containing impurities
Can be done. This is a silica gel chromatograph
(Solvent: for example, chloroform). Compound
The crystal modification of the product 1 depends on the extraction solvent. For example,
When precipitated from roloform solution, as shown in Figure 1
Giving an X-ray diffraction (XRD) spectrum (compound 1-
a). When precipitated from a dichloromethane solution, FIG.
Gives an X-ray diffraction (XRD) spectrum as shown in
(Compound 1-b).

XRD spectrum of compound 1-a (FIG. 1)
Are 9.6 ° and 17.2 of the Bragg angle (2θ ± 0.2 °).
{20.2}, 21.3}, 26.2}, 27.0
It was confirmed that this was a crystal modification showing strong diffraction peaks at {, 27.8} and 29.6 °. Compound 1-b
The XRD spectrum of FIG. 2 (FIG. 2) shows the Bragg angle (2θ ± 0.2).
゜) 15.3 ゜, 17.4 ゜, 19.0 ゜, 19.6
It was confirmed that the crystal modification had strong diffraction peaks at {, 25.2}, 27.1 °, and 31.3 °.

[0058]Example 1  In this example, the N-aryl substituted represented by the formula (I)
An azine-based compound (photoelectric conversion agent) is converted into a charge generation material (CG
Material applied to a laminated electrophotographic photoreceptor
explain. In addition, "part" in an Example shows a weight part.

Compound 1-a (2 parts), vinyl butyral resin [ELEX BH-3 (trade name) manufactured by Sekisui Chemical Co., Ltd.]
(1 part) and 1-propanol (100 parts) were mixed with glass beads (about 1 m in diameter) having the same volume as the mixed liquid.
m) together with shaking on a paint shaker. The resulting dispersion was applied on an aluminum-evaporated polyester film using an applicator to form a charge generation layer having a thickness of about 0.2 μm. Next, a mixed solution of p-dibenzylaminobenzaldehyde diphenylhydrazone (1 part), a polycarbonate resin and toluene (7 parts) is applied on the above-mentioned charge generating layer using an applicator to form a charge having a thickness of about 20 μm. A transport layer was created.

The electrical properties of the thus obtained laminated electrophotographic photosensitive member were evaluated using an electrophotographic electrostatic recording tester (SP-428, manufactured by Kawaguchi Electric). The measurement was performed with an applied voltage of -6.0 kV, static No. Performed in three modes.

As a result, the half-exposure amount was 1.5 lux.
Seconds and very high sensitivity.

Table 1 shows the compound 1 extracted by the above method.
5 shows the measurement results of half-exposure amounts of -a, compound 1-b, and compounds 4, 6 and 7. These all showed very high sensitivity.

[0063]

[Table 1]

[Brief description of the drawings]

FIG. 1 is an X-ray diffraction spectrum of compound 1-a.

FIG. 2 is an X-ray diffraction spectrum of compound 1-b.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 31/08

Claims (6)

[Claims] 1. A photoelectric conversion agent comprising a partially N-aryl-substituted azine compound represented by the following formula (I). Embedded image ... Formula (I) [In formula (I), R ¹ and R ² independently represent a hydrogen atom or a halogen atom, and R ³ and R ⁴ independently represent a substituent. Represents an aryl group which may have
⁵ and R ⁶ each independently represent a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, an arylamino group, an aryloxy group, or a halogen atom, and k, m, and n each represent a positive integer. Show. ] 2. The photoelectric conversion agent according to claim 1, wherein the partially N-aryl-substituted azine compound is an extract from a nigrosine compound. 3. The partially N-aryl-substituted azine compound has an X-ray diffraction spectrum by CuKα ray of Bragg angle (2θ ± 0.2 °) of 9.6 °, 17.2 °, 20.2 °.
2. The photoelectric conversion agent according to claim 1, wherein the photoelectric conversion agent has a crystal modification showing strong diffraction peaks at {, 21.3}, 26.2}, 27.0 °, 27.8 ° and 29.6 °. 4. An electrophotographic photosensitive member containing the photoelectric conversion agent according to claim 1, 2 or 3 in a charge generation layer. 5. An organic solar cell comprising the photoelectric conversion agent according to claim 1, 2 or 3 in a photocurrent generating layer. 6. A photoelectric conversion method comprising using a partially N-aryl-substituted azine compound represented by the following formula (I). Embedded image ... Formula (I) [In formula (I), R ¹ and R ² independently represent a hydrogen atom or a halogen atom, and R ³ and R ⁴ independently represent a substituent. Represents an aryl group which may have
⁵ and R ⁶ each independently represent a hydrogen atom, an alkyl group, an aralkyl group, an aryl group, an arylamino group, an aryloxy group, or a halogen atom, and k, m, and n each represent a positive integer. Show. ]