JP2018056546A - Material for photoelectric conversion element for image pickup element, and photoelectric conversion element including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a material for a photoelectric conversion element for an image pickup device, which is superior in the property of preventing a hole or electron from being leaked, the property of transporting a hole or electron, the resistance against heat of a process temperature, the transparency to visible light, etc.SOLUTION: A material for a photoelectric conversion element for an image pickup device comprises a compound represented by the formula (1) below. (In the formula (1), Rand Rrepresent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group; X's independently represent an oxygen atom, a sulfur atom or CRR; and Rand Rrepresent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group.)SELECTED DRAWING: None

Description

  The present invention relates to a photoelectric conversion element material for an imaging element that can be used for an imaging element, and a photoelectric conversion element for an imaging element comprising the photoelectric conversion element material for an imaging element.

  In recent years, interest in organic electronics devices has increased. Its features include a flexible structure and a large area, and further enabling an inexpensive and high-speed printing method in the electronic device manufacturing process. Typical devices include organic EL elements, organic solar cell elements, organic photoelectric conversion elements, organic transistor elements, and the like. Organic EL elements are expected as main targets for next-generation display applications as flat panel displays, and are applied to mobile phone displays, TVs, etc., and development aimed at further enhancement of functionality is being continued. Research and development have been made on organic solar cell elements and the like as flexible and inexpensive energy sources, and organic transistor elements and the like on flexible displays and inexpensive ICs.

  In developing an organic electronic device, it is very important to develop a material constituting the device. For this reason, many materials have been studied in each field, but they cannot be said to have sufficient performance, and even now, materials that are useful for various devices are being actively developed. Among them, a compound having benzothienobenzothiophene as a mother skeleton has also been developed as an organic electronics material (Patent Documents 1 to 3). When an alkyl derivative of benzothienobenzothiophene is used, a semiconductor thin film is formed by a printing process. However, it has a problem that the organic electronics device is inferior in heat resistance due to a relatively small number of condensed rings with respect to the alkyl chain length, which tends to cause a phase transition at a low temperature.

  In recent organic electronics, organic photoelectric conversion elements are expected to be developed into next-generation imaging elements, and reports have been made by several groups. For example, an example in which a quinacridone derivative or a quinazoline derivative is used as a photoelectric conversion element (Patent Document 4), an example in which a photoelectric conversion element using a quinacridone derivative is applied to an imaging element (Patent Document 5), and a diketopyrrolopyrrole derivative There is an example (Patent Document 6). In general, it is considered that the performance of an imaging device is improved by aiming at reduction of dark current for the purpose of high contrast and power saving. Therefore, in order to reduce the leakage current from the photoelectric conversion unit in the dark, a method of inserting a hole block layer or an electron block layer between the photoelectric conversion unit and the electrode unit is used.

  The hole blocking layer and the electron blocking layer are generally widely used in the field of organic electronics devices, and are arranged at the interface between the electrode or the conductive film and the other films in the component film of the device, respectively. It is a film that has the function of controlling the reverse movement of holes or electrons, and adjusts the leakage of unnecessary holes or electrons. Depending on the application of the device, heat resistance, transmission wavelength, film formation method, etc. These are selected and used in consideration of the characteristics. However, the required performance of materials especially for photoelectric conversion elements is high, and the conventional hole blocking layer or electron blocking layer is sufficient in terms of leakage current prevention characteristics, heat resistance to process temperature, transparency to visible light, etc. It cannot be said that it has a good performance and has not been utilized commercially.

JP 2008-2558592 A WO2008-047896 WO2010-098372 Japanese Patent No. 4945146 Japanese Patent No. 5022573 JP 2008-290963 A

J. Am. Chem. Soc., 2006, 128 (39), 12604.

  The present invention has been made in view of such a situation, and is excellent in hole or electron leakage prevention characteristics, hole or electron transport characteristics, heat resistance to process temperature, visible light transparency, and the like. It aims at providing the material for photoelectric conversion elements for image sensors which can be used for a conversion element.

As a result of diligent efforts to solve the above problems, the present inventors have found that the above problems can be solved by using a compound represented by the following formula (1), and have completed the present invention.
That is, the present invention is as follows.
[1] The following formula (1)

(In the formula (1), R ₁ and R ₂ are a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted hetero group. X represents independently an oxygen atom, a sulfur atom or CR ₃ R _4. R ₃ and R ₄ represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group. Or a substituted or unsubstituted heteroaryl group.) A material for a photoelectric conversion element for an image sensor, comprising a compound represented by:
(2) The following formula (2)

(In formula (2), R ₁ , R ₂ , X, R ₃ and R ₄ represent the same meaning as R ₁ , R ₂ , X, R ₃ and R ₄ in formula (1) according to claim 1. The material for a photoelectric conversion element for an image sensor according to the preceding item (1) represented by:
(3) The photoelectric conversion element material for an imaging element according to the above item (1) or (2), wherein R ₁ and R ₂ are hydrogen atoms,
(4) The photoelectric conversion element material for an imaging element according to any one of (1) to (3), wherein R ₃ and R ₄ are a hydrogen atom, a halogen atom, a methyl group, or a phenyl group,
(5) A photoelectric conversion element for an image sensor comprising the photoelectric conversion element material for an image sensor according to any one of (1) to (4) above,
(6) A photoelectric conversion element having a p-type organic semiconductor material and an n-type organic semiconductor material, wherein the p-type organic semiconductor material is a photoelectric conversion for an imaging element according to any one of (1) to (4) above. A photoelectric conversion element for an image sensor comprising an element material;
(7) (A) 1st electrode film, (B) 2nd electrode film, and (C) photoelectric conversion which has a photoelectric conversion part arrange | positioned between this 1st electrode film and this 2nd electrode film It is an element, Comprising: This (C) photoelectric conversion part contains organic thin-film layers other than (c-1) photoelectric conversion layer and (c-2) photoelectric conversion layer, and (c-2) photoelectric conversion An organic thin film layer other than the layer comprises the photoelectric conversion element material for an image sensor according to any one of (1) to (4),
(8) (c-2) The photoelectric conversion element for an image pickup device according to item (7), wherein the organic thin film layer other than the photoelectric conversion layer is an electron block layer,
(9) (c-2) The photoelectric conversion element for an image pickup device according to item (7), wherein the organic thin film layer other than the photoelectric conversion layer is a hole blocking layer,
(10) (c-2) The photoelectric conversion element for an image pickup device according to item (7), wherein the organic thin film layer other than the photoelectric conversion layer is an electron transport layer,
(11) (c-2) The photoelectric conversion element for an image pickup element according to item (7), wherein the organic thin film layer other than the photoelectric conversion layer is a hole transport layer,
(12) Any one of (5) to (11) above, further comprising (D) a thin film transistor having a hole accumulating portion and (E) a signal reading portion for reading a signal corresponding to the electric charge accumulated in the thin film transistor. The photoelectric conversion element for an image sensor according to the item,
(13) (D) The thin film transistor having a hole accumulating portion further includes (d) a connecting portion for electrically connecting the hole accumulating portion and one of the first electrode film and the second electrode film. The photoelectric conversion element for an image sensor according to the preceding item (12),
(14) An imaging device in which the photoelectric conversion elements for imaging devices according to any one of (5) to (13) are arranged in an array, and (15) any of (5) to (13) An optical sensor including the photoelectric conversion element for an imaging element according to one item or the imaging element according to the preceding item (14).

  According to the present invention, a novel imaging device using a compound represented by the formula (1), which is excellent in required properties such as hole or electron leakage prevention and transport properties, heat resistance and visible light transparency. A photoelectric conversion element can be provided.

Sectional drawing which illustrated the embodiment of the photoelectric conversion element for image sensors of this invention is shown.

  The contents of the present invention will be described in detail. The description of the constituent elements described below is based on typical embodiments and specific examples of the present invention, but the present invention is not limited to such embodiments and specific examples.

  The 1st characteristic of the photoelectric conversion element material for imaging devices of this invention exists in including the compound represented by following General formula (1).

In formula (1), R ₁ and R ₂ are a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl. Represents a group. X each independently represent an oxygen atom, a sulfur atom or a _CR 3 _{R 4.} R ₃ and R ₄ represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group.

Examples of the halogen atom represented by R ₁ and R _{2 in} Formula (1) include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, a fluorine atom, a chlorine atom or a bromine atom is preferable, and a fluorine atom is more preferable. Moreover, it is preferable that both R ₁ and R ₂ are the same halogen atom.

The alkyl group represented by R ₁ and R _{2 in} the formula (1) is not limited to any of linear, branched and cyclic, and the carbon number is not particularly limited, but usually has 1 to 4 carbon atoms. It is a linear or branched alkyl group or a cyclic alkyl group having 5 to 6 carbon atoms.
Specific examples of the alkyl group represented by R ₁ and R _{2 in} the formula (1) include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, an iso-butyl group, and a t-butyl group. , Sec-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, cyclopentyl group, cyclohexyl group and the like, preferably a linear or branched alkyl group having 1 to 4 carbon atoms. More preferably, it is a linear alkyl group having 1 or 2 carbon atoms.

Here, the “substituted or unsubstituted alkyl group” means an alkyl group in which a hydrogen atom in the alkyl group is substituted with a substituent or an alkyl group in which a hydrogen atom in the alkyl group is not substituted with a substituent. . When the alkyl group has a substituent, it is sufficient that the alkyl group has at least one substituent, and the substitution position and the number of substituents are not particularly limited.
In the present specification, the terms “substituted” and “unsubstituted” are the same as in the case of the alkyl group, “the hydrogen atom in the substituent is substituted with a substituent” and “in the substituent. In which the hydrogen atom is not substituted with a substituent.
Although there is no limit to the substituent having an alkyl group represented by R ₁ and R ₂ of formula (1), an alkoxy group, an aryl group, a halogen atom, a hydroxyl group, a mercapto group, a nitro group, an alkyl-substituted amino group, an aryl-substituted Examples thereof include an amino group, an unsubstituted amino group (NH ₂ group), a cyano group, and an isocyano group.

Specific examples of the alkoxy group as the substituent of the alkyl group represented by R ₁ and R _{2 in} Formula (1) include a methoxy group, an ethoxy group, a propoxy group, an iso-propoxy group, an n-butoxy group, and an iso-butoxy group. Group, t-butoxy group, n-pentyloxy group, iso-pentyloxy group, t-pentyloxy group, sec-pentyloxy group, n-hexyloxy group, iso-hexyloxy group, n-heptyloxy group, sec -Heptyloxy group, n-octyloxy group, n-nonyloxy group, sec-nonyloxy group, n-decyloxy group, n-undecyloxy group, n-dodecyloxy group, n-tridecyloxy group, n-tetradecyl group Oxy group, n-pentadecyloxy group, n-hexadecyloxy group, n-heptadecyloxy group, n-octa Siloxy group, n-nonadecyloxy group, n-eicosyloxy group, docosyloxy group, n-pentacosyloxy group, n-octacosyloxy group, n-tricontyloxy group, 5- (n-pentyl) decyloxy group , Heneicosyloxy group, tricosyloxy group, tetracosyloxy group, hexacosyloxy group, heptacosyloxy group, nonacosyloxy group, n-triacontyloxy group, squaryloxy group, dotriacontyl Examples thereof include an alkoxy group having 1 to 36 carbon atoms such as an oxy group and a hexatriacontyloxy group, preferably an alkoxy group having 1 to 24 carbon atoms, and more preferably an alkoxy group having 1 to 20 carbon atoms. Preferably, it is an alkoxy group having 1 to 12 carbon atoms, more preferably an alkoxy group having 1 to 6 carbon atoms. Particularly preferred is an alkoxy group having 1 to 4 carbon atoms, and most preferred.

The aryl group as a substituent of the alkyl group represented by R ₁ and R _{2 in} the formula (1) means a residue obtained by removing one hydrogen atom from an aryl compound. Specific examples thereof include a phenyl group, Biphenyl group, terphenyl group, naphthyl group, anthryl group, phenanthryl group, pyrenyl group, naphthacenyl group, chrycenyl group, fluorenyl group, fluoranthenyl group, triphenylene group, benzopyrenyl group and the like can be mentioned. Among these, a phenyl group, a biphenyl group, a naphthyl group or a fluorenyl group is preferable, a phenyl group, a biphenyl group or a naphthyl group is more preferable, and a phenyl group or a naphthyl group is more preferable. Moreover, it is preferable that both R ₁ and R ₂ are the same aryl group.
Examples of the halogen atom as the substituent of the alkyl group represented by R ₁ and R ₂ in Formula (1) include the same halogen atoms as those represented by R ₁ and R ₂ in Formula (1).

The alkyl-substituted amino group as a substituent that the alkyl group represented by R ₁ and R _{2 in} Formula (1) has is not limited to either a monoalkyl-substituted amino group or a dialkyl-substituted amino group. Examples of the alkyl group include the same alkyl groups represented by R ₁ and R ₂ in the formula (1).
The aryl-substituted amino group as a substituent that the alkyl group represented by R ₁ and R _{2 in} Formula (1) has is not limited to either a monoaryl-substituted amino group or a diaryl-substituted amino group. the aryl group include the same aryl groups as described in the section of a substituent having an alkyl group represented by R ₁ and R ₂ of formula (1).

The substituent that the alkyl group represented by R ₁ and R _{2 in} Formula (1) has is preferably an aryl group, a halogen atom, or an alkoxyl group, more preferably a halogen atom or an unsubstituted aryl group, More preferably, it is a phenyl group or a naphthyl group.

Specific examples of the alkoxy group represented by R ₁ and R ₂ in the formula (1) include the same examples as the specific examples of the alkoxy group as the substituent of the alkyl group represented by R ₁ and R _{2 in} the formula (1). The preferred ones are also the same.
Although there is no limitation on the substituent group of the alkoxy group represented by R ₁ and R ₂ of formula (1) may be the same as those for example the substituent group of the alkyl group represented by R ₁ and R ₂ of formula (1).

Specific examples of the aryl group represented by R ₁ and R ₂ in the formula (1) include the same examples as the specific examples of the aryl group as a substituent that the alkyl group represented by R ₁ and R _{2 in} the formula (1) has. The preferred ones are also the same.
Although there is no limitation on the substituent group of the aryl group represented by R ₁ and R ₂ of formula (1), the same thing can be mentioned a substituent having an alkyl group represented by R ₁ and R ₂ alkyl group and the formula (1) It is done.
Examples of the alkyl group as a substituent that the aryl group represented by R ₁ and R ₂ represented by Formula (1) has are the same as the alkyl groups represented by R ₁ and R ₂ represented by Formula (1).

The heteroaryl group represented by R ₁ and R _{2 in} the formula (1) means a residue obtained by removing one hydrogen atom from a heteroaryl compound, and specific examples thereof include a pyridyl group, a pyrazyl group, a pyrimidyl group, Heterocyclic groups such as quinolyl group, isoquinolyl group, pyrrolyl group, imidazolyl group, carbazolyl group, thienyl group, furyl group and pyranyl group, and condensed complex such as benzothienyl group, benzofuranyl group, dibenzothienyl group and dibenzofuranyl group A cyclic group etc. are mentioned. Of these, a pyridyl group, a quinolyl group, a carbazolyl group, a benzothienyl group, a benzofuranyl group, a dibenzothienyl group or a dibenzofuranyl group is preferable, a pyridyl group, a carbazolyl group, a benzothienyl group or a benzofuranyl is more preferable, and a pyridyl group or a benzofuranyl group is more preferable. More preferred is a thienyl group. Moreover, it is preferable that both R ₁ and R ₂ are the same heteroaryl group.
Although there is no limitation on the substituent group of the heteroaryl group represented by R ₁ and R ₂ of formula (1), the same as those of a substituent having an aryl group represented by R ₁ and R _2, for example the formula (1) .

R ₁ and R ₂ in formula (1) are preferably both hydrogen atoms, or both are the same unsubstituted aryl group, and both are hydrogen atoms, or both are the same phenyl group. More preferably, both are hydrogen atoms.

In formula (1), each X independently represents an oxygen atom, a sulfur atom or a divalent linking group CR ₃ R ₄ , wherein R ₃ and R ₄ are a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted group Alternatively, it represents an unsubstituted aryl group, or a substituted or unsubstituted heteroaryl group.

Specific examples of the halogen atom represented by R ₃ and R ₄ in the formula (1) include the same as the specific examples of the halogen atom represented by R ₁ and R _{2 in} the formula (1), and preferable ones are also the same. . Further, it is preferable that both R ₃ and R ₄ are the same halogen atom.

Specific examples of the alkyl group represented by R ₃ and R ₄ in the formula (1) include the same as the specific examples of the alkyl group represented by R ₁ and R _{2 in} the formula (1), and preferable ones are also the same. . Further, it is preferable that both R ₃ and R ₄ are the same alkyl group.
Although R ₃ and R ₄ are not limited to substituents having an alkyl group represented of the formula (1) may be the same as those for example the substituent group of the alkyl group represented by R ₁ and R ₂ of formula (1).

Specific examples of the aryl group represented by R ₃ and R ₄ in the formula (1) are the same as the specific examples of the aryl group as a substituent that the alkyl group represented by R ₁ and R _{2 in} the formula (1) has. The preferred ones are the same. Moreover, it is preferable that both R < ₃ > and R < ₄ > are the same aryl groups.
Although there is no limitation on the substituent group of the aryl group R ₃ and R ₄ represent the formula (1) may be the same as those for example the substituent group of the aryl group represented by R ₁ and R ₂ of formula (1).

Specific examples of the heteroaryl group represented by R ₃ and R ₄ in the formula (1) include the same as the specific examples of the heteroaryl group represented by R ₁ and R _{2 in} the formula (1), and preferable examples thereof are also the same. It is. Further, it is preferable that both R ₃ and R ₄ are the same heteroaryl groups.
Although there is no limitation on the substituent group of the heteroaryl group represented by R ₃ and R ₄ of formula (1), the same thing can be mentioned, for example, a substituent having a heteroaryl group represented by R ₁ and R ₂ of formula (1) It is done.

R ₃ and R ₄ in Formula (1) are preferably a hydrogen atom, a halogen atom, an unsubstituted alkyl group having 1 to 4 carbon atoms or an unsubstituted aryl group, and both R ₃ and R ₄ are More preferably, they are the same hydrogen atom, halogen atom, unsubstituted alkyl group having 1 to 4 carbon atoms or unsubstituted aryl group, and both are the same fluorine atom, hydrogen atom, unsubstituted carbon number 1 to 4 Are more preferably an alkyl group or a phenyl group, and both are particularly preferably the same unsubstituted alkyl group having 1 to 4 carbon atoms.

  The substitution position of the substituent on the benzene ring in the [1] benzothieno [3,2-b] [1] benzothiophene structure in the above formula (1) is not particularly limited, but is preferably the 2,7 position. That is, as the compound represented by the formula (1), a compound represented by the following general formula (2) is more preferable.

In the formula (2), R ₁ , R ₂ and X (R ₃ and R _{4 in} X) have the same meaning as R ₁ , R ₂ and X (R ₃ and R _{4 in} X) in the formula (1). The preferred ones are the same as those in the formula (1).
That is, as the compound represented by the formula (2), R ₁ , R ₂ and X (R ₃ and R _{4 in} X) in the formula (2) are preferable or most preferable in the above formula (1). Are preferred.

  Specific examples of the compound represented by the formula (1) are shown below, but the present invention is not limited to these specific examples.

  The compound represented by the formula (1) can be synthesized by a known method disclosed in Patent Document 1, Patent Document 6, and Non-Patent Document 1. For example, the method described in the following scheme is mentioned. Using the nitrostilbene derivative (A) as a raw material, a benzothienobenzothiophene skeleton (D) is formed and reduced to obtain an aminated product (E). If this compound (E) is halogenated, a halide (F) (iodide is described as an example in the following scheme) is obtained. If this compound (F) is further coupled with a boric acid derivative, the formula It is possible to obtain the compound represented by (1). The boric acid derivative here may be pinacol ester instead of free boric acid. In addition, according to the method of patent document 5, since the compound represented by Formula (1) can be manufactured in 1 step from a corresponding benzaldehyde derivative, it is more effective.

  The purification method of the compound represented by Formula (1) is not particularly limited, and known methods such as recrystallization, column chromatography, and vacuum sublimation purification can be employed. These methods can be combined as necessary.

  The photoelectric conversion element for an image sensor according to the present invention (hereinafter, also simply referred to as “photoelectric conversion element”) has two electrodes, that is, an opposing (A) first electrode film and (B) second electrode film. An element in which (C) a photoelectric conversion unit is arranged between the films, and light is incident on the photoelectric conversion unit from above (A) the first electrode film or (B) the second electrode film. . (C) The photoelectric conversion unit generates electrons and holes according to the incident light amount, and a signal according to the charge is read out by a semiconductor, and the incident light amount according to the absorption wavelength of the photoelectric conversion film unit. It is an element which shows. In some cases, a reading transistor is connected to the electrode film on which light is not incident. In the case where a large number of photoelectric conversion elements are arranged in an array, the photoelectric conversion element is an imaging element because it indicates incident position information in addition to the incident light quantity. If the photoelectric conversion element arranged closer to the light source does not shield (transmit) the absorption wavelength of the photoelectric conversion element arranged behind the light source when viewed from the light source side, a plurality of photoelectric conversion elements are stacked. It may be used. By laminating and using a plurality of photoelectric conversion elements having different absorption wavelengths in the visible light region, a multicolor imaging element (full color photodiode array) can be obtained.

The photoelectric conversion element material for an image sensor of the present invention is used as a material constituting the (C) photoelectric conversion unit.
(C) The photoelectric conversion part is (c-1) from the group consisting of a photoelectric conversion layer, an electron transport layer, a hole transport layer, an electron block layer, a hole block layer, a crystallization prevention layer, an interlayer contact improvement layer, and the like. It is often composed of one or a plurality of (c-2) organic thin film layers other than the selected photoelectric conversion layer. The photoelectric conversion element material for an image sensor of the present invention can be used for any of (c-1) a photoelectric conversion layer and (c-2) an organic thin film layer other than the photoelectric conversion layer. It is preferable to use for organic thin film layers other than the layer.

  (A) 1st electrode film and (B) 2nd electrode film which the photoelectric conversion element for image sensors of this invention has are contained in the (C) photoelectric conversion part mentioned later (c-1) photoelectric conversion layer In the case of having a hole transport property, (c-2) Organic thin film layer other than the photoelectric conversion layer (hereinafter, the organic thin film layer other than the photoelectric conversion layer is also simply referred to as “(c-2)) organic thin film layer”. ) Is a hole transporting layer having a hole transporting property, it plays a role of collecting and collecting holes from the (c-1) photoelectric conversion layer and the (c-2) organic thin film layer. In addition, when (c-1) the photoelectric conversion layer included in the photoelectric conversion part (C-1) has an electron transporting property, or (c-2) the organic thin film layer is an electron transporting layer having an electron transporting property, It serves to take out electrons from the (c-1) photoelectric conversion layer and the (c-2) organic thin film layer and discharge them. Therefore, the material that can be used as the (A) first electrode film and the (B) second electrode film is not particularly limited as long as it has a certain degree of conductivity, but the adjacent (c-1) photoelectric conversion layer. (C-2) It is preferable to select in consideration of adhesion to the organic thin film layer, electron affinity, ionization potential, stability, and the like. Examples of materials that can be used for (A) the first electrode film and (B) the second electrode film include tin oxide (NESA), indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO). Conductive metal oxide; metals such as gold, silver, platinum, chromium, aluminum, iron, cobalt, nickel and tungsten; inorganic conductive materials such as copper iodide and copper sulfide; conductive polymers such as polythiophene, polypyrrole and polyaniline Carbon etc. are mentioned. A plurality of these materials may be used as a mixture as necessary, or a plurality of these materials may be laminated in two or more layers. The conductivity of the material used for (A) the first electrode film and (B) the second electrode film is not particularly limited as long as it does not obstruct the light reception of the photoelectric conversion element more than necessary, but the signal intensity and consumption of the photoelectric conversion element It is preferable that it is as high as possible from the viewpoint of electric power. For example, an ITO film having a sheet resistance value of 300Ω / □ or less functions well as (A) the first electrode film and (B) the second electrode film, but has a conductivity of several Ω / □. Since a commercial product of a substrate provided with an ITO film having the above is also available, it is desirable to use a substrate having such high conductivity. The thickness of the ITO film (electrode film) can be arbitrarily selected in consideration of conductivity, but is usually about 5 to 500 nm, preferably about 10 to 300 nm. Examples of a method for forming a film such as ITO include conventionally known vapor deposition methods, electron beam methods, sputtering methods, chemical reaction methods, and coating methods. If necessary, the ITO film provided on the substrate may be subjected to UV-ozone treatment, plasma treatment, or the like.

Among the materials for the transparent electrode film used on at least one of the light incident side of (A) the first electrode film and (B) the second electrode film, ITO, IZO, SnO ₂ , ATO ( Antimony-doped tin oxide), ZnO, AZO (Al-doped zinc oxide), GZO (gallium-doped zinc oxide), TiO ₂ , FTO (fluorine-doped tin oxide), and the like. (C-1) The transmittance of light incident through the transparent electrode film at the absorption peak wavelength of the photoelectric conversion layer is preferably 60% or more, more preferably 80% or more, and 95% or more. It is particularly preferred.

  When a plurality of photoelectric conversion layers having different wavelengths to be detected are stacked, the electrode films used between the respective photoelectric conversion layers (this is other than (A) the first electrode film and (B) the second electrode film) It is necessary to transmit light having a wavelength other than the light detected by each photoelectric conversion layer, and the electrode film is preferably made of a material that transmits 90% or more of incident light. It is more preferable to use a material that transmits at least% of light.

  The electrode film is preferably made plasma-free. By producing these electrode films without plasma, the influence of plasma on the substrate on which the electrode films are provided is reduced, and the photoelectric conversion characteristics of the photoelectric conversion element can be improved. Here, plasma-free means that no plasma is generated when the electrode film is formed, or the distance from the plasma generation source to the substrate is 2 cm or more, preferably 10 cm or more, more preferably 20 cm or more, and reaches the substrate. It means a state where plasma is reduced.

  Examples of an apparatus that does not generate plasma when forming an electrode film include an electron beam vapor deposition apparatus (EB vapor deposition apparatus) and a pulse laser vapor deposition apparatus. Hereinafter, a method of forming a transparent electrode film using an EB vapor deposition apparatus is referred to as an EB vapor deposition method, and a method of forming a transparent electrode film using a pulse laser vapor deposition apparatus is referred to as a pulse laser vapor deposition method.

  As an apparatus that can realize a state in which plasma can be reduced during film formation (hereinafter referred to as a plasma-free film formation apparatus), for example, an opposed target sputtering apparatus, an arc plasma deposition apparatus, or the like can be considered.

  When the transparent conductive film is an electrode film (for example, the first conductive film), a DC short circuit or an increase in leakage current may occur. One of the causes is that a fine crack generated in the photoelectric conversion layer is covered with a dense film such as TCO (Transparent Conductive Oxide), and is between the electrode film (second conductive film) opposite to the transparent conductive film. This is thought to be due to increased conduction. For this reason, when a material such as Al that is inferior in film quality is used for the electrode, an increase in leakage current is unlikely to occur. By controlling the film thickness of the electrode film according to the film thickness (crack depth) of the photoelectric conversion layer, an increase in leakage current can be suppressed.

  Usually, when the conductive film is made thinner than a predetermined value, the resistance value increases rapidly. The sheet resistance of the conductive film in the photoelectric conversion element for an image sensor according to the present embodiment is usually 100 to 10,000 Ω / □, and the degree of freedom in film thickness is large. In addition, the thinner the transparent conductive film, the smaller the amount of light that is absorbed and the higher the light transmittance. High light transmittance is very preferable because light absorbed by the photoelectric conversion layer is increased and the photoelectric conversion performance is improved.

The (C) photoelectric conversion unit included in the photoelectric conversion element for an image sensor of the present invention includes at least an organic thin film layer other than (c-1) a photoelectric conversion layer and (c-2) a photoelectric conversion layer.
(C) An organic semiconductor film is generally used for the photoelectric conversion layer constituting the photoelectric conversion part. (C-1) The organic semiconductor film may be a single layer or a plurality of layers. A P-type organic semiconductor film, an N-type organic semiconductor film, or a mixed film thereof (bulk heterostructure) is used. On the other hand, in the case of a plurality of layers, it is about 2 to 10 layers, and has a structure in which any one of a P-type organic semiconductor film, an N-type organic semiconductor film, or a mixed film (bulk heterostructure) is laminated. A buffer layer may be inserted in

  (C-1) The organic semiconductor film of the photoelectric conversion layer has a triarylamine compound, a benzidine compound, a pyrazoline compound, a styrylamine compound, a hydrazone compound, a triphenylmethane compound, a carbazole compound, a polysilane compound depending on the wavelength band to be absorbed. Thiophene compound, phthalocyanine compound, cyanine compound, merocyanine compound, oxonol compound, polyamine compound, indole compound, pyrrole compound, pyrazole compound, polyarylene compound, carbazole derivative, naphthalene derivative, anthracene derivative, chrysene derivative, phenanthrene derivative, pentacene derivative, Phenylbutadiene derivatives, styryl derivatives, quinoline derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives, quinacridin Emissions derivatives, coumarin derivatives, porphyrin derivatives, fullerene derivatives and metal complexes (Ir complexes, Pt complexes, Eu complexes, etc.), or the like can be used.

  In the photoelectric conversion element for an image sensor of the present invention, (C) the organic thin film layer other than the photoelectric conversion layer constituting the photoelectric conversion unit is (c-1) a layer other than the photoelectric conversion layer, for example, an electron It is also used as a transport layer, a hole transport layer, an electron block layer, a hole block layer, a crystallization prevention layer, an interlayer contact improvement layer, or the like. In particular, when used as one or more thin film layers selected from the group consisting of an electron transport layer, a hole transport layer, an electron block layer and a hole block layer, an element capable of efficiently converting into an electric signal even with weak light energy can be obtained. Therefore, it is preferable.

The electron transport layer (c-1) transports electrons generated in the photoelectric conversion layer to (A) the first electrode film or (B) the second electrode film, and from the electrode transport destination electrode film (c -1) It plays the role of blocking the movement of holes to the photoelectric conversion layer.
The hole transport layer has the role of transporting the generated holes from (c-1) the photoelectric conversion layer to (A) the first electrode film or (B) the second electrode film, and the hole transport destination electrode film. (C-1) plays the role of blocking the movement of electrons to the photoelectric conversion layer.
The electron blocking layer prevents movement of electrons from (A) the first electrode film or (B) second electrode film to (c-1) the photoelectric conversion layer, and (c-1) within the photoelectric conversion layer. It serves to prevent recombination and reduce dark current.
The hole blocking layer prevents movement of holes from (A) the first electrode film or (B) second electrode film to (c-1) the photoelectric conversion layer, and (c-1) in the photoelectric conversion layer. It has a function of preventing recombination at the time and reducing dark current.
The hole blocking layer is formed by laminating or mixing hole blocking substances alone or in combination. The hole blocking substance is not limited as long as it is a compound that can prevent holes from flowing out of the element from the electrode. As compounds that can be used for the hole blocking layer, in addition to the compound represented by the general formula (1), phenanthroline derivatives such as bathophenanthroline and bathocuproin, silole derivatives, quinolinol derivative metal complexes, oxadiazole derivatives , An oxazole derivative, a quinoline derivative, and the like. Among these, one kind or two or more kinds can be used.
The electron blocking layer is formed by laminating or mixing electron blocking substances alone or in combination. The electron blocking substance is not limited as long as it is a compound that can block electrons from flowing out of the device. Examples of the compound that can be used for the electron blocking layer include arylamine derivatives and carbazole derivatives in addition to the compound represented by the general formula (1). Among these, 1 type, or 2 or more types can be used.

The organic thin film layer other than the (c-2) photoelectric conversion layer containing the compound represented by the general formula (1) can be suitably used particularly as a hole blocking layer or an electron blocking layer. From the viewpoint of preventing leakage current, the hole blocking layer or the electron blocking layer should be thicker, but from the viewpoint of obtaining a sufficient amount of current at the time of signal readout at the time of light incidence, the film thickness is The thinner one is better. In order to make these contradictory characteristics compatible, generally, the film thickness of the (C) photoelectric conversion part including (c-1) and (c-2) is preferably about 5 to 500 nm. Note that the function of the layer in which the compound represented by the general formula (1) is used varies depending on what other compound is used for the photoelectric conversion element.
In addition, the hole blocking layer and the electron blocking layer are preferably (c-1) high in transmittance of the absorption wavelength of the photoelectric conversion layer and used in a thin film so as not to prevent light absorption of the photoelectric conversion layer. preferable.

  The thin film transistor outputs a signal to the signal reading unit based on the electric charge generated by the photoelectric conversion unit. The thin film transistor includes a gate electrode, a gate insulating film, an active layer, a source electrode, and a drain electrode, and the active layer is formed of a silicon semiconductor, an oxide semiconductor, or an organic semiconductor.

  When an active layer used for a thin film transistor is formed using an oxide semiconductor, charge mobility is much higher than that of an amorphous silicon active layer, and it can be driven at a low voltage. In addition, when an oxide semiconductor is used, it is possible to form an active layer that is usually more light transmissive than silicon and has flexibility. An oxide semiconductor, particularly an amorphous oxide semiconductor, can be uniformly formed at a low temperature (for example, room temperature), and thus is particularly advantageous when a flexible resin substrate such as a plastic is used. Further, since a plurality of secondary light receiving pixels are stacked, the lower secondary light receiving pixels are affected when the upper secondary light receiving pixels are formed. In particular, the photoelectric conversion layer is easily affected by heat, but an oxide semiconductor, particularly an amorphous oxide semiconductor, is advantageous because it can be formed at a low temperature.

As the oxide semiconductor for forming the active layer, an oxide containing at least one of In, Ga, and Zn (for example, an In—O system) is preferable, and at least two of In, Ga, and Zn are used. Oxides containing (for example, In—Zn—O, In—Ga—O, and Ga—Zn—O) are more preferable, and oxides including In, Ga, and Zn are more preferable. As the In—Ga—Zn—O-based oxide semiconductor, an oxide semiconductor whose composition in a crystalline state is represented by InGaO ₃ (ZnO) m (m is a natural number less than 6) is preferable, and InGaZnO ₄ is particularly preferable. . As an amorphous oxide semiconductor having this composition, the electron mobility tends to increase as the electrical conductivity increases.

  The signal reading unit reads a charge generated and accumulated in the photoelectric conversion unit or a voltage corresponding to the charge.

  Although the typical element structure of the photoelectric conversion element for image sensors of this invention is demonstrated in detail in FIG. 1, this invention is not limited to these structures. In the embodiment of FIG. 1, 1 is an insulating part, 2 is one electrode film (first electrode film or second electrode film), 3 is an electron block layer, 4 is a photoelectric conversion layer, and 5 is a hole block. A layer, 6 represents the other electrode film (second electrode film or first electrode film), 7 represents an insulating base material, or a stacked photoelectric conversion element. The readout transistor (not shown in the drawing) only needs to be connected to either the electrode film 2 or 6, for example, if the photoelectric conversion layer 4 is transparent, the side opposite to the light incident side The film may be formed outside the electrode film (on the upper side of the electrode film 2 or on the lower side of the electrode film 6). If the thin film layer (electron block layer, hole block layer, etc.) other than the photoelectric conversion layer constituting the photoelectric conversion element does not extremely shield the absorption wavelength of the photoelectric conversion layer, the direction in which light is incident is the upper side (Fig. 1 or the lower portion (insulating substrate 7 side in FIG. 1).

  In the method for forming an organic thin film layer other than the (c-1) photoelectric conversion layer and the (c-2) photoelectric conversion layer in the photoelectric conversion element for an image pickup device of the present invention, generally, resistance heating vapor deposition that is a vacuum process, Electron beam deposition, sputtering, molecular lamination method, solution process casting, spin coating, dip coating, blade coating, wire bar coating, spray coating and other coating methods, inkjet printing, screen printing, offset printing, letterpress printing, etc. A soft lithography technique such as a printing method or a microcontact printing method, or a combination of these techniques may be employed. The thickness of each layer depends on the resistance value and charge mobility of each substance and cannot be limited, but is usually in the range of 7 to 5000 nm, preferably in the range of 1 to 1000 nm, more preferably in the range of 5 to 500 nm. Range.

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated still in detail, this invention is not limited to these examples.
The block layer described in the examples may be either a hole block layer or an electron block layer. The photoelectric conversion element is manufactured using a vapor deposition unit integrated with the glove box, and the photoelectric conversion element is installed in a sealed bottle-type measurement chamber (manufactured by ALS Technology) in a glove box in a nitrogen atmosphere. Then, current voltage application measurement was performed. Current voltage application measurement was performed using a semiconductor parameter analyzer 4200-SCS (Keithley Instruments) unless otherwise specified. Irradiation of incident light was performed using PVL-3300 (manufactured by Asahi Spectroscopic Co., Ltd.) at an irradiation light wavelength of 550 nm and an irradiation light half width of 20 nm unless otherwise specified. The light / dark ratio in the examples indicates a value obtained by dividing the current value in the case of light irradiation by the current value in a dark place.

Synthesis Example 1 (Synthesis of 2,7-bis (2-dibenzofuranyl) [1] benzothieno [3,2-b] [1] benzothiophene (compound represented by No. 1 in the specific example))
(Step 1) Synthesis of 2- (dibenzofuran-2-yl) -4,4,5,5-tetramethyl-1,3,2-dioxaborolane Toluene (150 parts) was added 2-bromodibenzofuran (5.0 parts). ), Bis (pinacolato) diboron (6.2 parts), potassium acetate (4.0 parts) and [1,1′-bis (diphenylphosphino) ferrocene] palladium (II) dichloride dichloromethane adduct (0.5 parts) ) And stirred at reflux temperature for 4 hours under a nitrogen atmosphere. The obtained reaction liquid was cooled to room temperature, solid content was separated by filtration, and a filtrate containing the product was obtained. Subsequently, it is purified by short silica gel column chromatography (developing solution; toluene), and the solvent is removed under reduced pressure to give 2- (dibenzofuran-2-yl) -4,4,5,5-tetramethyl-1,3. , 2-dioxaborolane (3.8 parts, yield 64%) was obtained.

(Step 2) Synthesis of 2,7-bis (2-dibenzofuranyl) [1] benzothieno [3,2-b] [1] benzothiophene DMF (250 parts), water (8.0 parts), patent 2,7-diiodo [1] benzothieno [3,2-b] [1] benzothiophene (4.7 parts) synthesized by the method described in No. 4945757, 2- (dibenzofuran-2 obtained in Step 1) -Yl) -4,4,5,5-tetramethyl-1,3,2-dioxaborolane (7.0 parts), tripotassium phosphate (8.1 parts) and tetrakis (triphenylphosphine) palladium (0. 6 parts) was mixed and stirred at 90 ° C. for 5 hours under a nitrogen atmosphere. After cooling the obtained reaction liquid to room temperature, water (250 parts) was added, and solid content was separated by filtration. The obtained solid content was washed with acetone and dried, followed by purification by sublimation, whereby No. in the above specific example. 1 (1.5 parts, 28% yield) was obtained.

Synthesis Example 2 (2,7-bis (9,9-dimethyl-9H-fluoren-2-yl) [1] benzothieno [3,2-b] [1] benzothiophene (represented by No. 12 in the specific example) Compound))
(Step 3) Synthesis of 2- (9,9-dimethyl-9H-fluoren-2-yl) -4,4,5,5-tetramethyl-1,3,2-dioxaborolane Toluene (250 parts) -Bromo-9,9-dimethylfluorene (10.0 parts), bis (pinacolato) diboron (11.2 parts), potassium acetate (7.2 parts) and [1,1'-bis (diphenylphosphino) ferrocene Palladium (II) dichloride dichloromethane adduct (0.9 parts) was mixed and stirred at reflux temperature for 3 hours under nitrogen atmosphere. The obtained reaction liquid was cooled to room temperature, solid content was separated by filtration, and a filtrate containing the product was obtained. Subsequently, it is purified by short silica gel column chromatography (developing solution; toluene), and the solvent is removed under reduced pressure to give 2- (9,9-dimethyl-9H-fluoren-2-yl) -4, 4, 5, 5-tetramethyl-1,3,2-dioxaborolane (11.1 parts, 95% yield) was obtained.

(Step 4) Synthesis of 2,7-bis (9,9-dimethyl-9H-fluoren-2-yl) [1] benzothieno [3,2-b] [1] benzothiophene DMF (300 parts) is mixed with water. (10.0 parts), 2,7-diiodo [1] benzothieno [3,2-b] [1] benzothiophene (7.1 parts) synthesized by the method described in Japanese Patent No. 4945757, obtained in Step 3. 2- (9,9-dimethyl-9H-fluoren-2-yl) -4,4,5,5-tetramethyl-1,3,2-dioxaborolane (11.1 parts), tripotassium phosphate ( 12.2 parts) and tetrakis (triphenylphosphine) palladium (0.9 parts) were mixed and stirred at 90 ° C. for 4 hours under a nitrogen atmosphere. After cooling the obtained reaction liquid to room temperature, water (250 parts) was added, and solid content was separated by filtration. The obtained solid content was washed with acetone and dried, followed by purification by sublimation, whereby No. in the above specific example. 12 (6.2 parts, 69% yield) was obtained.

Synthesis Example 3 (Synthesis of 2,7-bis (2-dibenzothienyl) [1] benzothieno [3,2-b] [1] benzothiophene (compound represented by No. 2 in the specific example))
(Step 5) Synthesis of 2- (dibenzothienyl-2-yl) -4,4,5,5-tetramethyl-1,3,2-dioxaborolane Toluene (250 parts) was added 2-bromodibenzothiophene (10. 0 part), bis (pinacolato) diboron (11.6 parts), potassium acetate (7.5 parts) and [1,1′-bis (diphenylphosphino) ferrocene] palladium (II) dichloride dichloromethane adduct (0. 9 parts) was mixed and stirred at reflux temperature for 4 hours under a nitrogen atmosphere. The obtained reaction liquid was cooled to room temperature, solid content was separated by filtration, and a filtrate containing the product was obtained. Subsequently, it is purified by short silica gel column chromatography (developing solution; toluene), and the solvent is removed under reduced pressure to give 2- (dibenzothienyl-2-yl) -4,4,5,5-tetramethyl-1, 3,2-Dioxaborolane (11.5 parts, 98% yield) was obtained.

(Step 6) Synthesis of 2,7-bis (2-dibenzothienyl) [1] benzothieno [3,2-b] [1] benzothiophene DMF (230 parts), water (7.0 parts), 2,7-diiodo [1] benzothieno [3,2-b] [1] benzothiophene (4.5 parts) synthesized by the method described in No. 4945757, 2- (dibenzothienyl-2 obtained in Step 5 -Yl) -4,4,5,5-tetramethyl-1,3,2-dioxaborolane (7.0 parts), tripotassium phosphate (7.7 parts) and tetrakis (triphenylphosphine) palladium (0. 6 parts) was mixed and stirred at 90 ° C. for 5 hours under a nitrogen atmosphere. After cooling the obtained reaction liquid to room temperature, water (250 parts) was added, and solid content was separated by filtration. The obtained solid content was washed with acetone and dried, followed by purification by sublimation, whereby No. in the above specific example. 2 (2.0 parts, yield 37%) was obtained.

Example 1 (Preparation of photoelectric conversion element and evaluation thereof)
2,7-bis (2-dibenzofuranyl) [1] benzothieno [3,2-b] [1] benzothiophene (Synthesis Example 1) on ITO transparent conductive glass (manufactured by Geomat Co., Ltd., ITO film thickness 150 nm) The compound represented by No. 1 obtained in 1) was formed as a block layer by resistance heating vacuum deposition to a thickness of 50 nm. Next, quinacridone was formed into a 100 nm vacuum film as a photoelectric conversion layer on the block layer. Finally, 100 nm of aluminum was vacuum-deposited as an electrode on the photoelectric conversion layer to produce a photoelectric conversion element for an image sensor according to the present invention. Using ITO and aluminum as electrodes, the contrast ratio when a voltage of 5 V was applied was 1.5 × 10 ⁴ .

Example 2 (Preparation of photoelectric conversion element and its evaluation)
Instead of 2,7-bis (2-dibenzofuranyl) [1] benzothieno [3,2-b] [1] benzothiophene (the compound represented by No. 1 obtained in Synthesis Example 1), 2 , 7-bis (9,9-dimethyl-9H-fluoren-2-yl) [1] benzothieno [3,2-b] [1] benzothiophene (represented by No. 12 obtained in Synthesis Example 2) Except that the compound) was used, the evaluation was performed according to Example 1. As a result, the contrast ratio when a voltage of 5 V was applied was 2.0 × 10 ⁵ .

Example 3 (Preparation of photoelectric conversion element and its evaluation)
Instead of 2,7-bis (2-dibenzofuranyl) [1] benzothieno [3,2-b] [1] benzothiophene (the compound represented by No. 1 obtained in Synthesis Example 1), 2 , 7-bis (2-dibenzothienyl) [1] benzothieno [3,2-b] [1] benzothiophene (the compound represented by No. 2 obtained in Synthesis Example 3), As a result of evaluation according to Example 1, the contrast ratio when a voltage of 5 V was applied was 4.0 × 10 ⁵ .

Comparative Example 1 (Production and Evaluation of Photoelectric Conversion Element)
Other than not using 2,7-bis (2-dibenzofuranyl) [1] benzothieno [3,2-b] [1] benzothiophene (the compound represented by No. 1 obtained in Synthesis Example 1) Was evaluated in accordance with Example 1, and the light / dark ratio when a voltage of 5 V was applied was 4.7.

Comparative Example 2 (Production and Evaluation of Photoelectric Conversion Element)
Instead of 2,7-bis (2-dibenzofuranyl) [1] benzothieno [3,2-b] [1] benzothiophene (the compound represented by No. 1 obtained in Synthesis Example 1), 2 , 7-diphenyl [1] benzothieno [3,2-b] [1] benzothiophene (a compound represented by the following formula (11)) was used, and evaluation was performed according to Example 1. The contrast ratio when a voltage of 5 V was applied was 600.

Comparative Example 3 (Production and Evaluation of Photoelectric Conversion Element)
Instead of 2,7-bis (2-dibenzofuranyl) [1] benzothieno [3,2-b] [1] benzothiophene (the compound represented by No. 1 obtained in Synthesis Example 1), tris Except that (8-quinolinolato) aluminum was used, the evaluation was performed according to Example 1. As a result, the contrast ratio was 31 when a voltage of 5 V was applied.

Comparative Example 4 (Production and Evaluation of Photoelectric Conversion Element)
Instead of 2,7-bis (2-dibenzofuranyl) [1] benzothieno [3,2-b] [1] benzothiophene (the compound represented by No. 1 obtained in Synthesis Example 1), 2 , 7-bis (9-phenanthrenyl)-[1] benzothieno [3,2-b] [1] benzothiophene (compound represented by the following formula (12)) was used according to Example 1 As a result, the contrast ratio when a voltage of 5 V was applied was 690.

Comparative Example 5 (Production and Evaluation of Photoelectric Conversion Element)
Instead of 2,7-bis (2-dibenzofuranyl) [1] benzothieno [3,2-b] [1] benzothiophene (the compound represented by No. 1 obtained in Synthesis Example 1), 2 , 7-bis (1-naphthyl)-[1] benzothieno [3,2-b] [1] benzothiophene (compound represented by the following formula (13)) was used in the same manner as in Example 1. As a result, the contrast ratio was 240 when a voltage of 5 V was applied.

Comparative Example 6 (Production and Evaluation of Photoelectric Conversion Element)
Instead of 2,7-bis (2-dibenzofuranyl) [1] benzothieno [3,2-b] [1] benzothiophene (the compound represented by No. 1 obtained in Synthesis Example 1), 2 , 7-bis (9H-carbazol-9-yl)-[1] benzothieno [3,2-b] [1] benzothiophene (compound represented by the following formula (14)) As a result of evaluation in accordance with Example 1, the light / dark ratio when a voltage of 5 V was applied was 47.

  The light / dark ratio obtained in the evaluation of Examples 1 and 2 clearly shows excellent characteristics as a photoelectric conversion element for an image sensor.

  From the above evaluation results, the photoelectric conversion element for an image sensor according to the example including the material for the photoelectric conversion element for an image sensor of the present invention including the compound represented by the formula (1) is the photoelectric sensor for the image sensor of the comparative example. Obviously, it has better properties than the conversion element.

  As described above, the photoelectric conversion element for an image pickup element including the material for the photoelectric conversion element for an image pickup element of the present invention including the compound represented by the formula (1) has excellent performance in organic photoelectric conversion characteristics. Organic imaging devices with high resolution and responsiveness as well as organic electronics devices such as organic EL devices, organic solar cell devices and organic transistor devices, optical sensors, infrared sensors, ultraviolet sensors, X-ray sensors, photon counters, etc. These devices are expected to be applied in the fields of devices, cameras using them, video cameras, infrared cameras, and the like.

DESCRIPTION OF SYMBOLS 1 Insulation part 2 Upper electrode 3 Electron block layer or hole transport layer 4 Photoelectric conversion part 5 Hole block layer or electron transport layer 6 Lower electrode 7 Insulating base material or other photoelectric conversion element

Claims (15)

Following formula (1)

(In the formula (1), R ₁ and R ₂ are a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted hetero group. X represents independently an oxygen atom, a sulfur atom or CR ₃ R _4. R ₃ and R ₄ represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group. Or a substituted or unsubstituted heteroaryl group.) A material for a photoelectric conversion element for an imaging element, comprising a compound represented by: Following formula (2)

(In formula (2), R ₁ , R ₂ , X, R ₃ and R ₄ represent the same meaning as R ₁ , R ₂ , X, R ₃ and R ₄ in formula (1) according to claim 1. The material for a photoelectric conversion element for an image sensor according to claim 1, which is represented by: The material for a photoelectric conversion element for an imaging element according to claim 1, wherein R ₁ and R ₂ are hydrogen atoms. The photoelectric conversion element material for an imaging element according to any one of claims 1 to 3, wherein R ₃ and R ₄ are a hydrogen atom, a halogen atom, a methyl group, or a phenyl group. A photoelectric conversion element for an image sensor comprising the photoelectric conversion element material for an image sensor according to any one of claims 1 to 4. A photoelectric conversion element having a p-type organic semiconductor material and an n-type organic semiconductor material, wherein the p-type organic semiconductor material includes the photoelectric conversion element material for an imaging element according to any one of claims 1 to 4. A photoelectric conversion element for an image sensor. A photoelectric conversion element having (A) a first electrode film, (B) a second electrode film, and (C) a photoelectric conversion unit disposed between the first electrode film and the second electrode film. The (C) photoelectric conversion part comprises at least (c-1) an organic thin film layer other than the photoelectric conversion layer and (c-2) the photoelectric conversion layer, and (c-2) other than the photoelectric conversion layer. A photoelectric conversion element for an image sensor, wherein the organic thin film layer comprises the photoelectric conversion element material for an image sensor according to any one of claims 1 to 4. (C-2) The organic thin film layer other than the photoelectric conversion layer is an electronic block layer, The photoelectric conversion element for an image pickup device according to claim 7. (C-2) The photoelectric conversion element for an image pickup device according to claim 7, wherein the organic thin film layer other than the photoelectric conversion layer is a hole blocking layer. (C-2) The organic thin film layer other than the photoelectric conversion layer is an electron transport layer, The photoelectric conversion element for an image pickup device according to claim 7. (C-2) The organic thin film layer other than the photoelectric conversion layer is a hole transport layer, The photoelectric conversion element for an image pickup device according to claim 7. The image pickup device according to any one of claims 5 to 11, further comprising (D) a thin film transistor having a hole accumulating portion, and (E) a signal reading portion for reading a signal corresponding to the electric charge accumulated in the thin film transistor. Photoelectric conversion element. (D) The thin film transistor having a hole accumulating portion further includes (d) a connecting portion that electrically connects the hole accumulating portion and one of the first electrode film and the second electrode film. The photoelectric conversion element for image sensors described in 2. An image sensor in which a plurality of photoelectric conversion elements for an image sensor according to any one of claims 5 to 13 are arranged in an array. An optical sensor including the photoelectric conversion element for an imaging element according to any one of claims 5 to 13 or the imaging element according to claim 14.

Images