JP5890366B2 - Photoelectric conversion device, imaging device, optical sensor - Google Patents

Description

  The present invention relates to a photoelectric conversion element, an imaging element, and an optical sensor.

  A conventional optical sensor is an element in which a photodiode (PD) is formed in a semiconductor substrate such as silicon (Si). As a solid-state image sensor, signal charges generated in each PD are arranged in two dimensions. Are widely used.

In order to realize a color solid-state imaging device, a structure in which a color filter that transmits light of a specific wavelength is arranged on the light incident surface side of the flat solid-state imaging device is generally used. Color filters that transmit blue (B) light, green (G) light, and red (R) light are regularly arranged on each two-dimensionally arranged PD that is currently widely used in digital cameras and the like. Single-plate solid-state imaging devices are well known.
In this single-plate solid-state imaging device, the light that has not passed through the color filter is not used and the light use efficiency is poor. In recent years, as the number of pixels has increased, the pixel size has been reduced, and a decrease in aperture ratio and a decrease in light collection efficiency have become problems.

In order to solve these drawbacks, a structure is known in which a photoelectric conversion film made of amorphous silicon or a photoelectric conversion film is formed on a signal readout substrate.
There are some known examples of photoelectric conversion elements, imaging elements, and optical sensors using a photoelectric conversion film.
For example, Patent Document 1 discloses a photoelectric conversion film containing a compound (3) represented by the following formula in the example column, and states that it has high photoelectric conversion efficiency. Patent Documents 2 and 3 also disclose photoelectric conversion elements containing a diketopyrrolopyrrole compound.

JP 2006-339424 A JP 2010-192882 A JP 2003-346926 A

In recent years, along with demands for improving the performance of imaging devices, optical sensors, etc., improvements have also been demanded with respect to various characteristics such as heat resistance and response speed required for photoelectric conversion films used for these. For example, when applying a photoelectric conversion element to various uses, such as an image pick-up element and a photovoltaic cell, it is calculated | required that a photoelectric conversion element shows high heat resistance from the point of process suitability. More specifically, as a process for forming an image sensor, there are many processes for heat treatment such as color filter installation, protective film installation, element soldering, etc., and the photoelectric conversion element is excellent even after these processes. Exhibiting characteristics (response speed, low dark current characteristics, etc.).
When the present inventors made a photoelectric conversion film using the compounds specifically disclosed in Patent Documents 1 to 3 (for example, the above-mentioned compound 3), they are not necessarily in terms of heat resistance and response speed. We have not reached the level required recently, and found that further improvement is necessary.

An object of this invention is to provide a photoelectric conversion element provided with the photoelectric converting film which shows the outstanding heat resistance and responsiveness in view of the said situation.
Another object of the present invention is to provide an image sensor and a photosensor including a photoelectric conversion element.

As a result of intensive studies on the above problems, the present inventors have determined a diketopyrrolopyrrole compound contained in a photoelectric conversion film or a compound obtained by further condensing an aromatic ring between two pyrrole rings of diketopyrrolopyrrole. It has been found that the above-mentioned problems can be solved by introducing an aromatic ring-containing amine group at the position, and the present invention has been completed.
That is, the above problems can be solved by the following means.

(1) A photoelectric conversion element formed by laminating a conductive film, a photoelectric conversion film containing a photoelectric conversion material, and a transparent conductive film in this order,
The photoelectric conversion material is selected from the group consisting of a compound represented by general formula (1) described later, a compound represented by general formula (2) described later, and a compound represented by general formula (3) described later. A photoelectric conversion element comprising at least one compound X.
(2) The photoelectric conversion element according to (1), wherein the compound X is a compound represented by the general formula (4) described later.
(3) Ar ¹ and R ¹¹ , Ar ¹ and R ¹² , R ¹¹ and R ¹² , Ar ² and R ¹³ , Ar ² and R ¹⁴ , and R ¹³ and R ¹⁴ are bonded to each other to form a ring The photoelectric conversion element according to (1) or (2).
(4) The photoelectric conversion element according to any one of (1) to (3), wherein X ¹ and X ² are O.
(5) The photoelectric conversion element according to any one of (1) to (4), wherein the photoelectric conversion film further contains an organic n-type compound.
(6) The photoelectric conversion element according to (5), wherein the organic n-type compound includes fullerenes including fullerene and a derivative thereof.

(7) The photoelectric conversion element according to (6), wherein the molar ratio of compound X to fullerene (molar amount of fullerene / molar amount of compound X) is 1.0 or more.
(8) The photoelectric conversion element according to any one of (1) to (7), wherein a charge blocking film is disposed between the conductive film and the transparent conductive film.
(9) An imaging device including the photoelectric conversion device according to any one of (1) to (8).
(10) An optical sensor including the photoelectric conversion element according to any one of (1) to (8).

ADVANTAGE OF THE INVENTION According to this invention, a photoelectric conversion element provided with the photoelectric converting film which shows the outstanding heat resistance and responsiveness can be provided.
Moreover, according to this invention, the image pick-up element and optical sensor containing a photoelectric conversion element can be provided.

FIG. 1A and FIG. 1B are schematic cross-sectional views each showing a configuration example of a photoelectric conversion element. It is a cross-sectional schematic diagram for 1 pixel of an image sensor.

Below, the suitable embodiment of the photoelectric conversion element of this invention is demonstrated.
First, the feature point compared with the prior art of this invention is explained in full detail.
As described above, in the present invention, a fragrance is present at a predetermined position in a diketopyrrolopyrrole compound contained in a photoelectric conversion film or a compound obtained by further condensing an aromatic ring between two pyrrole rings of diketopyrrolopyrrole. It has been found that a desired effect can be obtained by introducing a group ring-containing amine group. By introducing such an amine group containing an aromatic ring, the molecular weight of the compound to be used is increased, the interaction between the compounds is appropriately increased, and the degree of freedom of the molecule is reduced by introducing more ring structures. As a result, it is presumed that the heat resistance has been improved. Also, by introducing an aromatic ring-containing amine group, a skeleton that can hold holes stably projects to the outside of the molecule, which facilitates the exchange of holes between molecules, resulting in improved response speed It is guessed.

Below, the suitable embodiment of the photoelectric conversion element of this invention is demonstrated with reference to drawings. In FIG. 1, the cross-sectional schematic diagram of one Embodiment of the photoelectric conversion element of this invention is shown.
A photoelectric conversion element 10a shown in FIG. 1A includes a conductive film (hereinafter also referred to as a lower electrode) 11 that functions as a lower electrode, an electron blocking film 16A formed on the lower electrode 11, and an electron blocking film 16A. The photoelectric conversion film 12 formed above and a transparent conductive film (hereinafter also referred to as an upper electrode) 15 functioning as an upper electrode are stacked in this order.
FIG. 1B shows a configuration example of another photoelectric conversion element. The photoelectric conversion element 10b shown in FIG. 1B has a configuration in which an electron blocking film 16A, a photoelectric conversion film 12, a hole blocking film 16B, and an upper electrode 15 are laminated on the lower electrode 11 in this order. Have. Note that the stacking order of the electron blocking film 16A, the photoelectric conversion film 12, and the hole blocking film 16B in FIGS. 1A and 1B may be reversed depending on the application and characteristics. For example, the positions of the electron blocking film 16A and the photoelectric conversion film 12 may be reversed.

In the configuration of the photoelectric conversion element 10 a (10 b), it is preferable that light is incident on the photoelectric conversion film 12 through the transparent conductive film 15.
Moreover, when using the photoelectric conversion element 10a (10b), an electric field can be applied. In this case, it is preferable that the conductive film 11 and the transparent conductive film 15 form a pair of electrodes, and an electric field of 1 × 10 ⁻⁵ to 1 × 10 ⁷ V / cm is applied between the pair of electrodes. From the viewpoint of performance and power consumption, an electric field of 1 × 10 ⁻⁴ to 1 × 10 ⁶ V / cm is preferable, and an electric field of 1 × 10 ^{−3 to} 5 × 10 ⁵ V / cm is particularly preferable.
In addition, about the voltage application method, in FIG. 1 (a) and (b), it is preferable to apply so that the electron blocking film | membrane 16A side may become a cathode and the photoelectric converting film 12 side may become an anode. When the photoelectric conversion element 10a (10b) is used as an optical sensor, or when it is incorporated into an image sensor, voltage can be applied by the same method.

Below, the aspect of each layer (The photoelectric conversion film 12, the electron blocking film | membrane 16A, the lower electrode 11, the upper electrode 15, the hole blocking film | membrane 16B etc.) which comprises the photoelectric conversion element 10a (10b) is explained in full detail.
First, the photoelectric conversion film 12 will be described in detail.

[Photoelectric conversion film]
The photoelectric conversion film 12 is a compound represented by the general formula (1) described later as a photoelectric conversion material, a compound represented by the general formula (2) described later, and a compound represented by the general formula (3) described later. A membrane comprising at least one compound X selected from the group consisting of By using the compound X, a photoelectric conversion film exhibiting excellent heat resistance and high-speed response can be obtained.
First, the compounds represented by the general formulas (1) to (3) used in the photoelectric conversion film 12 will be described in detail.

In General Formula (1) to General Formula (3), R ¹ and R ² each independently represents an alkyl group, an aryl group, or a heteroaryl group. Especially, an alkyl group is preferable at the point which is easy to synthesize | combine and the characteristics (heat resistance and responsiveness) of a photoelectric converting film are more excellent.
Although carbon number in an alkyl group is not specifically limited, 1-10 are preferable, 1-6 are more preferable, and 1-3 are more preferable at the point which the characteristic (heat resistance and responsiveness) of a photoelectric converting film is more excellent. The alkyl group may have a linear, branched or cyclic structure.
Preferred examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an n-butyl group, and an n-hexyl group.

Although carbon number in an aryl group is not specifically limited, 6-30 are preferable and 6-18 are more preferable at the point which the characteristic (heat resistance and responsiveness) of a photoelectric converting film is more excellent. The aryl group may be a monocyclic structure or a condensed ring structure in which two or more rings are condensed, and may have a substituent W described later.
Examples of the aryl group include a phenyl group, a naphthyl group, an anthryl group, a pyrenyl group, a phenanthrenyl group, a methylphenyl group, a dimethylphenyl group, a biphenyl group, and a fluorenyl group. A phenyl group, a naphthyl group, or an anthryl group is exemplified. preferable.

The number of carbon atoms in the heteroaryl group (monovalent aromatic heterocyclic group) is not particularly limited, but is preferably 3 to 30, more preferably 3 to 18 in terms of more excellent characteristics (heat resistance and responsiveness) of the photoelectric conversion film. Is more preferable. The heteroaryl group may have a substituent W described later.
The heteroaryl group includes a heteroatom other than a carbon atom and a hydrogen atom. Examples of the heteroatom include a nitrogen atom, a sulfur atom, an oxygen atom, a selenium atom, a tellurium atom, a phosphorus atom, a silicon atom, or a boron atom. And a nitrogen atom, a sulfur atom, or an oxygen atom is preferable. The number of heteroatoms contained in the heteroaryl group is not particularly limited, and is usually about 1 to 10, preferably 1 to 4.
The number of members of the heteroaryl group is not particularly limited, but is preferably a 3- to 8-membered ring, more preferably a 5- to 7-membered ring, and particularly preferably a 5- to 6-membered ring.
Examples of heteroaryl groups include pyridyl, quinolyl, isoquinolyl, acridinyl, phenanthridinyl, pteridinyl, pyrazinyl, quinoxalinyl, pyrimidinyl, quinazolyl, pyridazinyl, cinnolinyl, phthalazinyl, Triazinyl group, oxazolyl group, benzoxazolyl group, thiazolyl group, benzothiazolyl group, imidazolyl group, benzoimidazolyl group, pyrazolyl group, indazolyl group, isoxazolyl group, benzisoxazolyl group, isothiazolyl group, benzoisothiazolyl group, oxadiazolyl Group, thiadiazolyl group, triazolyl group, tetrazolyl group, furyl group, benzofuryl group, thienyl group, benzothienyl group, dibenzofuryl group, dibenzothienyl group, pyrrolyl group, indoline Group, imidazopyridinyl group, and carbazolyl group.

It describes about the substituent W in this specification.
Examples of the substituent W include a halogen atom, an alkyl group (including a cycloalkyl group, a bicycloalkyl group, and a tricycloalkyl group), an alkenyl group (including a cycloalkenyl group and a bicycloalkenyl group), an alkynyl group, an aryl group, and a heterocyclic ring. Group (may be referred to as a heterocyclic group), cyano group, hydroxy group, nitro group, carboxy group, alkoxy group, aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyloxy group , Aryloxycarbonyloxy group, amino group (including anilino group), ammonio group, acylamino group, aminocarbonylamino group, alkoxycarbonylamino group, aryloxycarbonylamino group, sulfamoylamino group, alkyl or arylsulfonylamino Group, mercapto group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, sulfo group, alkyl or arylsulfinyl group, alkyl or arylsulfonyl group, acyl group, aryloxycarbonyl group, alkoxycarbonyl group, carbamoyl group, aryl Alternatively, a heterocyclic azo group, imide group, phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, phosphono group, silyl group, hydrazino group, ureido group, boronic acid group (-B (OH) ₂ ) , Phosphato groups (—OPO (OH) ₂ ), sulfato groups (—OSO ₃ H), and other known substituents.
The details of the substituent W are described in paragraph [0023] of JP-A-2007-234651.

R ¹¹ , R ¹² , R ¹³ and R ¹⁴ each independently represents an alkyl group, an aryl group or a heteroaryl group. Note that at least one of R ¹¹ and R ¹² and at least one of R ¹³ and R ¹⁴ each represents an aryl group or a heteroaryl group. Among them, in that the characteristics of the photoelectric conversion layer (heat resistance and responsiveness) more excellent, it is preferable R ^11, R ^12, R ¹³ and R ¹⁴ are aryl groups.
The definitions and preferred embodiments of the alkyl group, aryl group and heteroaryl group represented by R ¹¹ , R ¹² , R ¹³ and R ¹⁴ are the alkyl group, aryl group and heteroaryl group represented by R ¹ and R ² above. The definition and preferred embodiments are the same.

Ar ¹ and Ar ² each independently represent an arylene group or a heteroarylene group. Especially, it is preferable that Ar < ¹ > and Ar < ² > are arylene groups at the point which the characteristic (heat resistance and responsiveness) of a photoelectric converting film is more excellent.
Although carbon number in an arylene group is not restrict | limited in particular, 6-30 are preferable and 6-20 are more preferable at the point which the characteristic (heat resistance and responsiveness) of a photoelectric converting film is more excellent.
Examples of the arylene group include phenylene group, biphenylene group, terphenylene group, naphthylene group, anthrylene group, phenanthrylene group, pyrenediyl group, perylenediyl group, fluorenediyl group, chrysenediyl group, triphenylenediyl group, benzoanthracenediyl group, benzoic group Examples include phenanthrene diyl group.

Although carbon number in particular in a heteroarylene group is not restrict | limited, 1-20 are preferable and 2-12 are more preferable at the point which the characteristic (heat resistance and responsiveness) of a photoelectric converting film is more excellent.
Examples of the heteroarylene group include a pyridylene group, a quinolylene group, an isoquinolylene group, an acridinediyl group, a phenanthridinediyl group, a pyrazinediyl group, a quinoxalinediyl group, a pyrimidinediyl group, a triazinediyl group, an imidazolediyl group, a pyrazolediyl group, Examples thereof include an oxadiazole diyl group, a triazole diyl group, a furylene group, a thienylene group, a pyrrole diyl group, an indole diyl group, and a carbazole diyl group.

X ¹ and X ² are each independently, O (oxygen atom), S (sulfur atom), or an NR ^A. Among these, O (oxygen atom) or S (sulfur atom) is preferable, and O (oxygen atom) is more preferable in that the characteristics (heat resistance and responsiveness) of the photoelectric conversion film are more excellent.
R ^A represents an alkyl group, an aryl group, or a heteroaryl group. Especially, an alkyl group is preferable at the point which the characteristic (heat resistance and responsiveness) of a photoelectric converting film is more excellent.
The definitions and preferred embodiments of the alkyl group, aryl group and heteroaryl group represented by R ^A are the same as the definitions and preferred embodiments of the alkyl group, aryl group and heteroaryl group represented by R ¹ and R ² above. .

  Q is a group represented by the general formula (A), a group represented by the general formula (B), a group represented by the general formula (C), a group represented by the general formula (D), and It is any one group selected from the group consisting of groups represented by formula (E).

In general formula (A) to general formula (E), R ^{Q1 to} R ^Q22 each independently represent a hydrogen atom or a substituent. Examples of the substituent include the substituent W described above, and examples thereof include an alkyl group, an alkoxy group, and a halogen atom. Especially, it is preferable that R ^{< Q1} > -R ^<Q22> is a hydrogen atom at the point which the characteristic (heat resistance or responsiveness) of a photoelectric conversion element is more excellent.
In addition, the carbon atom shown by * 1- * 4 in general formula (A)-general formula (E) is each shown by * 1- * 4 in general formula (1)-general formula (3). Corresponds to a carbon atom. More specifically, examples of structural formulas in the case where groups represented by general formulas (A) to (E) are introduced into Q in general formulas (1) to (3) below. Indicates.

In the general formula (1) to general formula (3), Ar ¹ and R ¹¹ , Ar ¹ and R ¹² , R ¹¹ and R ¹² , Ar ² and R ¹³ , Ar ² and R ¹⁴ , R ¹³ and R ¹⁴ are respectively They may combine with each other to form a ring. At the time of bonding, Ar ¹ and R ¹¹ , Ar ¹ and R ¹² , R ¹¹ and R ¹² , Ar ² and R ¹³ , Ar ² and R ¹⁴ , R ¹³ and R ¹⁴ are each directly or via a linking group. Are preferably bonded to form a ring, and more preferably bonded directly to form a ring in terms of more excellent characteristics (heat resistance and responsiveness) of the photoelectric conversion film.
By forming the ring structure, the heat resistance of the compounds represented by the general formulas (1) to (3) is improved, and a photoelectric conversion element can be produced at a high vapor deposition rate under high temperature conditions. In addition, the responsiveness is further improved.
The structure of the linking group is not particularly limited. For example, an oxygen atom, a sulfur atom, an alkylene group, a silylene group, an alkenylene group, a cycloalkylene group, a cycloalkenylene group, an arylene group, a divalent heterocyclic group, an imino group, Or the group which combined these is mentioned, These may have a substituent further. An alkylene group, a silylene group, an alkenylene group, a cycloalkylene group, a cycloalkenylene group, an arylene group and the like are preferable.
The structure of the ring formed is not particularly limited, and for example, a benzene ring, a naphthalene ring, an anthracene ring, a phenanthrene ring, a fluorene ring, a triphenylene ring, a naphthacene ring, a biphenyl ring, a pyrrole ring, a furan ring, a thiophene ring, an imidazole ring, Oxazole ring, thiazole ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, indolizine ring, indole ring, benzofuran ring, benzothiophene ring, isobenzofuran ring, quinolidine ring, quinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring Quinoxazoline ring, isoquinoline ring, carbazole ring, phenanthridine ring, acridine ring, phenanthroline ring, thianthrene ring, chromene ring, xanthene ring, phenoxathiin ring, phenothiazine ring, phenazine ring, cyclopenta Ring, cyclohexane ring, pyrrolidine ring, piperidine ring, a tetrahydrofuran ring, tetrahydropyran ring, a tetrahydrothiophene ring, a tetrahydrothiopyran ring.

At least one of Ar ¹ and R ¹¹ , Ar ¹ and R ¹² , and R ¹¹ and R ¹² is bonded to each other to form a ring, and Ar ² and R ¹³ , Ar ² and R ¹⁴ , and R It is preferable that at least one of ¹³ and R ¹⁴ is bonded to each other to form a ring. If it is such an aspect, the heat resistance and responsiveness of a photoelectric converting film will improve more.

n represents 0 or 1. Especially, it is preferable that n is 0 at the point which the characteristic (heat resistance or responsiveness) of a photoelectric conversion element is more excellent.
When n is 1, the compounds represented by the above general formula (1A) to general formula (3E) are exemplified.
When n is 0, the carbon atom indicated by * 1 and the carbon atom indicated by * 3 are the same carbon atom, and the carbon atom indicated by * 2 and the carbon atom indicated by * 4 are the same. Becomes a carbon element. That is, in the general formulas (1) to (3), when n = 0, the compounds represented by the following general formulas (4) to (6) are represented.
In addition, the definition of each group in General formula (4)-General formula (6) is as above-mentioned.

Especially, the compound represented by General formula (4) is especially preferable at the point which the effect of this invention is more excellent. The compound represented by the general formula (4) is a so-called diketopyrrolopyrrole compound.
Examples of the compounds represented by the general formulas (1) to (3) are shown below.

The compounds represented by the general formulas (1) to (3) preferably have an absorption maximum at 400 nm or more and less than 720 nm in the ultraviolet-visible absorption spectrum. The peak wavelength (absorption maximum wavelength) of the absorption spectrum is more preferably 450 nm or more and 700 nm or less, more preferably 480 nm or more and 700 nm or less, and more preferably 510 nm or more and 680 nm or less from the viewpoint of broadly absorbing light in the visible region. Particularly preferred.
The absorption maximum wavelength of the compound can be measured by using a chloroform solution of the compound with UV-2550 manufactured by Shimadzu Corporation. The concentration of the chloroform solution is preferably 5 × 10 ⁻⁵ to 1 × 10 ⁻⁷ mol / l, more preferably 3 × 10 ⁻⁵ to 2 × 10 ⁻⁶ mol / l, and 2 × 10 ^{−5 to} 5 × 10 ^{−. 6} mol / l is particularly preferred.

The compound represented by the general formula (1) to the general formula (3) has an absorption maximum at 400 nm or more and less than 720 nm in the ultraviolet-visible absorption spectrum, and the molar extinction coefficient at the absorption maximum wavelength is 10,000 mol ⁻¹ · l · cm. It is preferably ⁻¹ or more. In order to reduce the film thickness of the photoelectric conversion film and obtain an element having high charge collection efficiency, high-speed response, and high sensitivity characteristics, a material having a large molar extinction coefficient is preferable. More preferably 30000mol ^-1 · l · cm ^-1 or more as a molar extinction coefficient of the formulas (1) to (3), compounds represented by a further preferred 50000mol ^-1 · l · cm ^-1 or more. The molar extinction coefficient of the compounds represented by the general formula (1) to the general formula (3) is measured with a chloroform solution.

  As the difference between the melting point and the deposition temperature (melting point-deposition temperature) increases, the compound represented by the general formula (1) to the general formula (3) is less likely to be decomposed during the deposition. can do. Further, the difference between the melting point and the deposition temperature (melting point−deposition temperature) is preferably 40 ° C. or higher, more preferably 50 ° C. or higher, still more preferably 60 ° C. or higher, and particularly preferably 80 ° C. or higher.

  300-1500 are preferable, as for the molecular weight of the compound represented by General formula (1)-General formula (3), 500-1000 are more preferable, and 500-900 are especially preferable. When the molecular weight of the compound is 1500 or less, the deposition temperature does not increase and the compound is hardly decomposed. If the molecular weight of the compound is 300 or more, the glass transition point of the deposited film is not lowered, and the heat resistance of the device is hardly lowered.

  The glass transition point (Tg) of the compound represented by the general formula (1) to the general formula (3) is preferably 95 ° C. or higher, more preferably 110 ° C. or higher, further preferably 135 ° C. or higher, particularly 150 ° C. or higher. Preferably, 160 ° C. or higher is most preferable. A high glass transition point is preferable because the heat resistance of the device is improved.

  The compounds represented by the general formula (1) to the general formula (3) are particularly useful as a material for a photoelectric conversion film used for an image sensor, an optical sensor, or a photovoltaic cell. In general, the compound represented by the general formula (1) functions as an organic p-type compound in the photoelectric conversion film. As other applications, it can also be used as a coloring material, liquid crystal material, organic semiconductor material, organic light emitting device material, charge transport material, pharmaceutical material, fluorescent diagnostic material, and the like.

(Other materials)
The photoelectric conversion film may further contain a photoelectric conversion material of an organic p-type compound or an organic n-type compound.
The organic p-type semiconductor (compound) is a donor-type organic semiconductor (compound), which is mainly represented by a hole-transporting organic compound and refers to an organic compound having a property of easily donating electrons. More specifically, an organic compound having a smaller ionization potential when two organic materials are used in contact with each other. Therefore, any organic compound can be used as the donor organic compound as long as it is an electron-donating organic compound. For example, a triarylamine compound, a benzidine compound, a pyrazoline compound, a styrylamine compound, a hydrazone compound, a triphenylmethane compound, a carbazole compound, or the like can be used.

  An organic n-type semiconductor (compound) is an acceptor organic semiconductor, and is mainly represented by an electron-transporting organic compound and means an organic compound having a property of easily accepting electrons. More specifically, the organic compound having the higher electron affinity when two organic compounds are used in contact with each other. Therefore, any organic compound may be used as the acceptor organic semiconductor as long as it is an organic compound having an electron accepting property. Preferably, fullerene or a fullerene derivative, a condensed aromatic carbocyclic compound (naphthalene derivative, anthracene derivative, phenanthrene derivative, tetracene derivative, pyrene derivative, perylene derivative, fluoranthene derivative), nitrogen atom, oxygen atom, sulfur atom 5 7-membered heterocyclic compounds (eg, pyridine, pyrazine, pyrimidine, pyridazine, triazine, quinoline, quinoxaline, quinazoline, phthalazine, cinnoline, isoquinoline, pteridine, acridine, phenazine, phenanthroline, tetrazole, pyrazole, imidazole, thiazole, oxazole, indazole , Benzimidazole, benzotriazole, benzoxazole, benzothiazole, carbazole, purine, triazolopyridazine, tria Ropyrimidine, tetrazaindene, oxadiazole, imidazopyridine, pyralidine, pyrrolopyridine, thiadiazolopyridine, dibenzoazepine, tribenzazepine, etc.), polyarylene compounds, fluorene compounds, cyclopentadiene compounds, silyl compounds, nitrogen-containing heterocycles Examples thereof include metal complexes having a compound as a ligand.

As the organic n-type compound, fullerenes selected from the group consisting of fullerenes and fullerene derivatives are preferable. The fullerene, fullerene C _60, fullerene C _70, fullerene C _76, fullerene C _78, fullerene C _80, fullerene C _82, fullerene C _84, fullerene C _90, fullerene C _96, fullerene C _240, fullerene C _540, mixed Fullerene is represented, and the fullerene derivative represents a compound having a substituent added thereto. As the substituent, an alkyl group, an aryl group, or a heterocyclic group is preferable. As a fullerene derivative, the compound as described in Unexamined-Japanese-Patent No. 2007-123707 is preferable.

  The photoelectric conversion film preferably has a bulk heterostructure formed in a state where the compound X and fullerenes are mixed. A bulk heterostructure is a layer in which a p-type organic semiconductor (compound X) and an n-type organic semiconductor are mixed and dispersed in a photoelectric conversion film, and can be formed by either a wet method or a dry method. Those that do are preferred. By including the heterojunction structure, it is possible to make up for the disadvantage that the carrier diffusion length of the photoelectric conversion film is short, and to improve the photoelectric conversion efficiency of the photoelectric conversion film. The bulk heterojunction structure is described in detail in JP-A-2005-303266, [0013] to [0014].

  The molar ratio of the organic n-type compound to the compound X (organic n-type compound / the compound X) in the photoelectric conversion film is preferably 1.0 or more, more preferably 1 or more and 10 or less, and more preferably 2 or more. More preferably, it is 8 or less.

  The photoelectric conversion film containing the compound X and the organic n-type compound of the present invention is a non-light-emitting film and has characteristics different from those of an organic electroluminescent element (OLED). The non-light-emitting film is a film having an emission quantum efficiency of 1% or less, more preferably 0.5% or less, and still more preferably 0.1% or less.

(Film formation method)
The photoelectric conversion film 12 can be formed by a dry film formation method or a wet film formation method. Specific examples of the dry film forming method include a physical vapor deposition method such as a vacuum deposition method, a sputtering method, an ion plating method, and an MBE method, or a CVD method such as plasma polymerization. As the wet film forming method, a casting method, a spin coating method, a dipping method, an LB method, or the like is used. A dry film forming method is preferable, and a vacuum evaporation method is more preferable. When forming a film by a vacuum evaporation method, manufacturing conditions such as the degree of vacuum and the evaporation temperature can be set according to a conventional method.

  The thickness of the photoelectric conversion film 12 is preferably 10 nm to 1000 nm, more preferably 50 nm to 800 nm, and particularly preferably 100 nm to 500 nm. By setting it to 10 nm or more, a suitable dark current suppressing effect is obtained, and by setting it to 1000 nm or less, suitable photoelectric conversion efficiency is obtained.

[electrode]
The electrodes (upper electrode (transparent conductive film) 15 and lower electrode (conductive film) 11) are made of a conductive material. As the conductive material, a metal, an alloy, a metal oxide, an electrically conductive compound, or a mixture thereof can be used.
Since light is incident from the upper electrode 15, the upper electrode 15 needs to be sufficiently transparent to the light to be detected. Specifically, conductive metal oxides such as tin oxide (ATO, FTO) doped with antimony or fluorine, tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), Metal thin films such as gold, silver, chromium, nickel, etc., and mixtures or laminates of these metals and conductive metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, organics such as polyaniline, polythiophene, and polypyrrole Examples thereof include conductive materials and laminates of these with ITO. Among these, a transparent conductive metal oxide is preferable from the viewpoint of high conductivity and transparency.

  Usually, when the conductive film is made thinner than a certain range, a rapid increase in resistance value is caused. However, in the solid-state imaging device incorporating the photoelectric conversion element according to the present embodiment, the sheet resistance is preferably 100 to 10,000 Ω / □. Well, there is a large degree of freedom in the range of film thickness that can be made thin. Further, as the thickness of the upper electrode (transparent conductive film) 15 decreases, the amount of light absorbed decreases, and the light transmittance generally increases. An increase in light transmittance is very preferable because it increases the light absorption in the photoelectric conversion film 12 and increases the photoelectric conversion ability. Considering the suppression of leakage current, the increase in the resistance value of the thin film, and the increase in transmittance due to the thinning, the thickness of the upper electrode 15 is preferably 5 to 100 nm, more preferably 5 to 20 nm. It is desirable.

  Depending on the application, the lower electrode 11 may have transparency, or conversely, may use a material that does not have transparency and reflects light. Specifically, conductive metal oxides such as tin oxide (ATO, FTO) doped with antimony or fluorine, tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), Metals such as gold, silver, chromium, nickel, titanium, tungsten, and aluminum, and conductive compounds such as oxides and nitrides of these metals (for example, titanium nitride (TiN)), and these metals and conductivity Examples include mixtures or laminates with metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, organic conductive materials such as polyaniline, polythiophene, and polypyrrole, and laminates of these with ITO or titanium nitride. .

The method for forming the electrode is not particularly limited, and can be appropriately selected depending on the electrode material. Specifically, it can be formed by a wet method such as a printing method or a coating method, a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, or a chemical method such as CVD or plasma CVD method.
When the material of the electrode is ITO, it can be formed by a method such as an electron beam method, a sputtering method, a resistance heating vapor deposition method, a chemical reaction method (such as a sol-gel method), or a dispersion of indium tin oxide. Furthermore, UV-ozone treatment, plasma treatment, or the like can be performed on a film formed using ITO. When the electrode material is TiN, various methods including a reactive sputtering method can be used, and further UV-ozone treatment, plasma treatment, and the like can be performed.

[Charge blocking film: electron blocking film, hole blocking film]
The photoelectric conversion element of the present invention may have a charge blocking film. By having this film, the characteristics (photoelectric conversion efficiency, response speed, etc.) of the obtained photoelectric conversion element are more excellent. Examples of the charge blocking film include an electron blocking film and a hole blocking film. Below, each film | membrane is explained in full detail.

(Electronic blocking film)
An electron donating organic material can be used for the electron blocking film. Specifically, for low molecular weight materials, N, N′-bis (3-methylphenyl)-(1,1′-biphenyl) -4,4′-diamine (TPD) or 4,4′-bis [N Aromatic diamine compounds such as-(naphthyl) -N-phenyl-amino] biphenyl (α-NPD), oxazole, oxadiazole, triazole, imidazole, imidazolone, stilbene derivative, pyrazoline derivative, tetrahydroimidazole, polyarylalkane, butadiene 4,4 ′, 4 ″ tris (N- (3-methylphenyl) N-phenylamino) triphenylamine (m-MTDATA), porphyrin, tetraphenylporphyrin copper, phthalocyanine, copper phthalocyanine, titanium phthalocyanine oxide, etc. Compounds, triazole derivatives, oxazizazole derivatives, Midazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, silazane derivatives, etc. can be used. As the molecular material, polymers such as phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, diacetylene, and derivatives thereof can be used. Any compound having transportability can be used, and specifically, compounds described in [0083] to [0089] of JP-A-2008-72090 are preferred.

  It is also preferable that the electron blocking film contains a compound represented by the general formula (F-1). By using this compound, the response speed of the obtained photoelectric conversion film is more excellent, and variations in the response speed between the manufacturing rods are further suppressed.

(In General Formula (F-1), R ″ _{11 to} R ″ ₁₈ and R ′ _{11 to} R ′ ₁₈ are each independently a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a heterocyclic group, a hydroxyl group, or an amino group. Or a mercapto group, which may further have a substituent. Any one of R ″ _{15 to} R ″ ₁₈ is linked to any one of R ′ _{15 to} R ′ _18. , .A ₁₁ and a ₁₂ form a single bond represents a group each represented independently by the following general formula (a-1), R " 11 ~R" 14, and R _'11 to R' in the ₁₄ Y is each independently a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, or a silicon atom, which may further have a substituent.

(In the general formula (A-1), Ra _{1 to} Ra ₈ each independently represents a hydrogen atom, a halogen atom, an alkyl group, an aryl group, or a heterocyclic group, and these further have a substituent. * Represents a bonding position, Xa is a single bond, oxygen atom, sulfur atom, alkylene group, silylene group, alkenylene group, cycloalkylene group, cycloalkenylene group, arylene group, divalent heterocyclic group, or Represents an imino group, which may further have a substituent, each of S ₁₁ independently represents the following substituent (S ₁₁ ), and is substituted as any one of Ra _{1 to} Ra _8. Represents an integer of 0 to 4.)

(R ′ _{1 to} R ′ ₃ each independently represents a hydrogen atom or an alkyl group.)

In general formula (F-1), R ″ _{11 to} R ″ ₁₈ and R ′ _{11 to} R ′ ₁₈ are each independently a hydrogen atom, a halogen atom, an alkyl group, an aryl group, a heterocyclic group, a hydroxyl group, an amino group, Alternatively, it represents a mercapto group, and these may further have a substituent. Specific examples of the further substituent include the substituent W described above, preferably a halogen atom, an alkyl group, an aryl group, a heterocyclic group, a hydroxyl group, an amino group, or a mercapto group, more preferably a halogen atom, an alkyl group. A group, an aryl group, or a heterocyclic group, more preferably a fluorine atom, an alkyl group, or an aryl group, particularly preferably an alkyl group or an aryl group, and most preferably an alkyl group.
R ″ _{11 to} R ″ ₁₈ and R ′ _{11 to} R ′ ₁₈ are preferably a hydrogen atom, an alkyl group which may have a substituent, an aryl group, or a heterocyclic group, more preferably a hydrogen atom. , An optionally substituted alkyl group having 1 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, or a heterocyclic group having 4 to 16 carbon atoms. Among them, it is preferable that the substituent represented by the general formula (A-1) is independently substituted with R ″ ₁₂ and R ′ ₁₂ , and the substituent represented by the general formula (A-1) is R ″ ₁₂ and R ′ ₁₂ is each independently substituted, and R ″ _11, R ″ _{13 to} R ″ ₁₈ , R ′ _{11, and} R ′ _{13 to} R ′ _{18 each} have a hydrogen atom and optionally have 1 to 1 carbon atoms. More preferably, the substituent represented by formula (A-1) is each independently substituted with R ″ ₁₂ and R ′ ₁₂ , and R ″ _11, R ″ _13- R ″ ₁₈ , R ′ _{11 and} R ′ _{13 to} R ′ ₁₈ are hydrogen atoms.

Y independently represents a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, or a silicon atom, and these may further have a substituent. That is, Y represents a divalent linking group composed of a carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom, or a silicon atom. Among _{-C (R '21) (R} ' 22) -, - Si (R '23) (R' 24) -, - N (R '20) -, preferably, -C (R' ₂₁₎ ( R ′ ₂₂ ) — and —N (R ′ ₂₀ ) — are more preferable, and —C (R ′ ₂₁ ) (R ′ ₂₂ ) — is particularly preferable.
R ′ _{20 to} R ′ ₂₄ each independently represents a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an aryl group, a heterocyclic group, a hydroxyl group, an amino group, or a mercapto group. Specific examples of the further substituent include the substituent W. R ′ _{20 to} R ′ ₂₄ are preferably a hydrogen atom, an alkyl group which may have a substituent, an aryl group, or a heterocyclic group, more preferably a hydrogen atom or a substituent. A good alkyl group having 1 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, or a heterocyclic group having 4 to 16 carbon atoms, more preferably a hydrogen atom or an optionally substituted carbon number. It is a C1-C18 alkyl group, Most preferably, it is a C1-C18 alkyl group.

Ra _{1 to} Ra ₈ in the general formula (A-1) are each independently a hydrogen atom, a halogen atom, an optionally substituted alkyl group, an aryl group, a heterocyclic group, a hydroxyl group, an amino group, or Represents a mercapto group. Specific examples of the further substituent include the substituent W. In addition, a plurality of these substituents may be bonded to each other to form a ring.

Ra _{1 to} Ra ₈ are preferably a hydrogen atom, a halogen atom, an alkyl group having 1 to 18 carbon atoms, an aryl group having 6 to 18 carbon atoms, or a heterocyclic group having 4 to 16 carbon atoms, and preferably a hydrogen atom or carbon number. An alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 14 carbon atoms is more preferable, and a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms is still more preferable. The alkyl group may be branched.
Preferable specific examples include a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, a cyclohexyl group, a phenyl group, or a naphthyl group.
Further, it is particularly preferable that Ra ₃ and Ra ₆ are a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and Ra ₁ , Ra ₂ , Ra ₄ , Ra ₅ , Ra ₇ and Ra ₈ are a hydrogen atom. .

Xa represents a single bond, an oxygen atom, a sulfur atom, an alkylene group, a silylene group, an alkenylene group, a cycloalkylene group, a cycloalkenylene group, an arylene group, a divalent heterocyclic group, or an imino group, and these further represent a substituent. You may have.
Xa is a single bond, an alkylene group having 1 to 12 carbon atoms, an alkenylene group having 2 to 12 carbon atoms, an arylene group having 6 to 14 carbon atoms, a heterocyclic group having 4 to 13 carbon atoms, an oxygen atom, a sulfur atom, carbon An imino group (for example, phenylimino group, methylimino group, t-butylimino group) having 1 to 12 hydrocarbon groups (preferably an aryl group or an alkyl group) or a silylene group is preferable, and a single bond, an oxygen atom, or a carbon number 1 to 6 alkylene groups (for example, methylene group, 1,2-ethylene group, 1,1-dimethylmethylene group), alkenylene groups having 2 carbon atoms (for example, —CH ₂ ═CH ₂ —), 6 to 10 carbon atoms An arylene group (for example, 1,2-phenylene group, 2,3-naphthylene group) or a silylene group is more preferable, and a single bond, an oxygen atom, or an alkylene group having 1 to 6 carbon atoms (for example, a methyl group). Down group, 1,2-ethylene group, 1,1-dimethylmethylene group) is more preferred. These substituents may further have a substituent W.
Specific examples of the group represented by the general formula (A-1) include groups exemplified by the following N1 to N11. However, it is not limited to these. The group represented by formula (A-1) is preferably N-1 to N-7, more preferably N-1 to N-6, more preferably N-1 to N-3, and N-1 -N-2 is particularly preferred, and N-1 is most preferred.

In the substituent (S ₁₁ ), R ′ ₁ represents a hydrogen atom or an alkyl group. R ′ ₁ is preferably a methyl group, an ethyl group, a propyl group, an iso-propyl group, a butyl group, or a tert-butyl group, more preferably a methyl group, an ethyl group, a propyl group, an iso-propyl group, or A tert-butyl group, more preferably a methyl group, an ethyl group, an iso-propyl group, or a tert-butyl group, and particularly preferably a methyl group, an ethyl group, or a tert-butyl group.

R ′ ₂ represents a hydrogen atom or an alkyl group. R ′ ₂ is preferably a hydrogen atom, methyl group, ethyl group, propyl group, iso-propyl group, butyl group, or tert-butyl group, more preferably a hydrogen atom, methyl group, ethyl group, or propyl group. More preferably a hydrogen atom or a methyl group, and particularly preferably a methyl group.

R ′ ₃ represents a hydrogen atom or an alkyl group. R ′ ₃ is preferably a hydrogen atom or a methyl group, more preferably a methyl group.

R ′ _{1 to} R ′ ₃ may be bonded to each other to form a ring. When forming a ring, the number of ring members is not particularly limited, but is preferably a 5- or 6-membered ring, more preferably a 6-membered ring.

S ₁₁ represents the above substituent (S ₁₁ ) and is substituted as any one of Ra _{1 to} Ra ₈ . It is preferable that at least one of Ra ₃ and Ra ₆ in the general formula (A-1) independently represents the substituent (S ₁₁ ).
Preferred examples of the substituent (S ₁₁ ) include the following (a) to (x), (a) to (j) are more preferable, (a) to (h) are more preferable, and (a) to ( f) is particularly preferable, (a) to (c) are more preferable, and (a) is most preferable.

  n ′ each independently represents an integer of 0 to 4, preferably 0 to 3, more preferably 0 to 2, still more preferably 1 to 2, and particularly preferably 2.

  The general formula (A-1) is a group represented by the following general formula (A-3), a group represented by the following general formula (A-4), or a group represented by the following general formula (A-5). It may be a group.

(In the general formulas (A-3) to (A-5), Ra _{33 to} Ra ₃₈ , Ra ₄₁ , Ra _{44 to} Ra ₄₈ , Ra ₅₁ , Ra ₅₂ , Ra _{55 to} Ra ₅₈ are each independently a hydrogen atom. , A halogen atom, or an alkyl group, which may further have a substituent, * represents a bonding position, Xc ₁ , Xc ₂ , and Xc ₃ are each independently a single bond, an oxygen atom, sulfur atom, an alkylene group, a silylene group, an alkenylene group, cycloalkylene group, cycloalkenylene group, an arylene group, divalent heterocyclic group or an imino group, and these may have a substituent .Z ₃₁ , Z ₄₁ , and Z ₅₁ each independently represents a cycloalkyl ring, an aromatic hydrocarbon ring, or an aromatic heterocyclic ring, which may further have a substituent.

In the general formulas (A-3) to (A-5), Ra _{33 to} Ra ₃₈ , Ra ₄₁ , Ra _{44 to} Ra ₄₈ , Ra ₅₁ , Ra ₅₂ , Ra _{55 to} Ra ₅₈ are each independently a hydrogen atom, A halogen atom (preferably a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom) or an alkyl group is represented. A hydrogen atom or an alkyl group is preferable and a hydrogen atom is more preferable because a substituent having a low polarity is advantageous for hole transport.
When Ra _{33 to} Ra ₃₈ , Ra ₄₁ , Ra _{44 to} Ra ₄₈ , Ra ₅₁ , Ra ₅₂ , Ra _{55 to} Ra ₅₈ represent an alkyl group, the alkyl group is preferably an alkyl group having 1 to 18 carbon atoms, A C1-C12 alkyl group is more preferable, and a C1-C6 alkyl group is still more preferable. Specifically, a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, or a cyclohexyl group is preferable.
In the general formulas (A-3) to (A-5), adjacent ones of Ra _{33 to} Ra ₃₈ , Ra ₄₁ , Ra _{44 to} Ra ₄₈ , Ra ₅₁ , Ra ₅₂ , Ra _{55 to} Ra ₅₈ are bonded to each other. To form a ring. Examples of the ring include the aforementioned ring R. The ring is preferably a benzene ring, naphthalene ring, anthracene ring, pyridine ring, pyrimidine ring or the like.

Xc ₁ , Xc ₂ , and Xc ₃ are each independently a single bond, an oxygen atom, a sulfur atom, an alkylene group, a silylene group, an alkenylene group, a cycloalkylene group, a cycloalkenylene group, an arylene group, or a divalent heterocyclic group. Or an imino group. When Xc ₁ , Xc ₂ , and Xc ₃ represent an alkylene group, a silylene group, an alkenylene group, a cycloalkylene group, a cycloalkenylene group, an arylene group, a divalent heterocyclic group, or an imino group, these further represent a substituent. You may have. Examples of the further substituent include the substituent W.

Xc _1, Xc _2, and Xc ₃ is a single bond, an alkylene group having 1 to 12 carbon atoms, an alkenylene group having 2 to 12 carbon atoms, an arylene group having 6 to 14 carbon atoms, heterocyclic group of 4 to 13 carbon atoms , An oxygen atom, a sulfur atom, an imino group having a hydrocarbon group having 1 to 12 carbon atoms (preferably an aryl group or an alkyl group) (for example, phenylimino group, methylimino group, t-butylimino group) is preferable, An alkylene group having 1 to 6 carbon atoms (for example, methylene group, 1,2-ethylene group, 1,1-dimethylmethylene group), an alkenylene group having 2 carbon atoms (for example, —CH ₂ ═CH ₂ —), carbon number 6 to 10 arylene groups (for example, 1,2-phenylene group and 2,3-naphthylene group) are more preferable.

Z ₃₁ , Z ₄₁ , and Z ₅₁ each independently represent a cycloalkyl ring, an aromatic hydrocarbon ring, or an aromatic heterocyclic ring. In the general formulas (A-3) to (A-5), Z ₃₁ , Z ₄₁ , and Z ₅₁ are condensed with a benzene ring. Z ₃₁ , Z ₄₁ , and Z ₅₁ are preferably aromatic hydrocarbon rings because the photoelectric conversion element can be expected to have high heat resistance and high hole transport ability.

The electron blocking film may be composed of a plurality of films.
An inorganic material can also be used as the electron blocking film. In general, since an inorganic material has a dielectric constant larger than that of an organic material, a large voltage is applied to the photoelectric conversion film when used as an electron blocking film, and the photoelectric conversion efficiency can be increased. Materials that can be used as electron blocking films include calcium oxide, chromium oxide, chromium copper oxide, manganese oxide, cobalt oxide, nickel oxide, copper oxide, gallium copper oxide, strontium copper oxide, niobium oxide, molybdenum oxide, indium copper oxide, and oxide. Examples include indium silver and iridium oxide. In the case where the electron blocking film is a single layer, the layer can be a layer made of an inorganic material, or in the case of a plurality of layers, one or more layers can be a layer made of an inorganic material. .

(Hole blocking film)
An electron-accepting organic material can be used for the hole blocking film.
Examples of electron accepting materials include 1,3-bis (4-tert-butylphenyl-1,3,4-oxadiazolyl) phenylene (OXD-7) and other oxadiazole derivatives, anthraquinodimethane derivatives, and diphenylquinone derivatives. , Bathocuproine, bathophenanthroline, and derivatives thereof, triazole compounds, tris (8-hydroxyquinolinato) aluminum complexes, bis (4-methyl-8-quinolinato) aluminum complexes, distyrylarylene derivatives, silole compounds, etc. Can do. Further, even if it is not an electron-accepting organic material, it can be used as long as it has a sufficient electron transport property. A porphyrin compound, a styryl compound such as DCM (4-dicyanomethylene-2-methyl-6- (4- (dimethylaminostyryl))-4H pyran), or a 4H pyran compound can be used. Specifically, compounds described in JP-A-2008-72090, [0073] to [0078] are preferable.

  The method for producing the charge blocking film is not particularly limited, and can be formed by a dry film forming method or a wet film forming method. As a dry film forming method, a vapor deposition method, a sputtering method, or the like can be used. The vapor deposition may be either physical vapor deposition (PVD) or chemical vapor deposition (CVD), but physical vapor deposition such as vacuum vapor deposition is preferred. As a wet film forming method, an inkjet method, a spray method, a nozzle printing method, a spin coating method, a dip coating method, a casting method, a die coating method, a roll coating method, a bar coating method, a gravure coating method, etc. can be used. From the viewpoint of high-precision patterning, the inkjet method is preferable.

  The thickness of the charge blocking film (electron blocking film and hole blocking film) is preferably 10 to 200 nm, more preferably 30 to 150 nm, and particularly preferably 50 to 100 nm. This is because if the thickness is too thin, the dark current suppressing effect is lowered, and if it is too thick, the photoelectric conversion efficiency is lowered.

[substrate]
The photoelectric conversion element may further include a substrate. The type of the substrate used is not particularly limited, and a semiconductor substrate, a glass substrate, or a plastic substrate can be used.
The position of the substrate is not particularly limited, but usually a conductive film, a photoelectric conversion film, and a transparent conductive film are laminated on the substrate in this order.
[Sealing layer]
The photoelectric conversion element may further include a sealing layer. The performance of photoelectric conversion materials may deteriorate significantly due to the presence of degradation factors such as water molecules. Ceramics such as dense metal oxides, metal nitrides, and metal nitride oxides that do not penetrate water molecules and diamond-like materials Covering and sealing the entire photoelectric conversion film with a sealing layer such as carbon (DLC) can prevent the deterioration.
In addition, as a sealing layer, you may select and manufacture a material according to description of Paragraph [0210]-[0215] of Unexamined-Japanese-Patent No. 2011-082508.

[Optical sensor]
Examples of the use of the photoelectric conversion element include a photovoltaic cell and an optical sensor, but the photoelectric conversion element of the present invention is preferably used as an optical sensor. As an optical sensor, the photoelectric conversion element used alone may be used, or a line sensor in which the photoelectric conversion elements are linearly arranged or a two-dimensional sensor arranged on a plane is preferable. The photoelectric conversion element of the present invention converts optical image information into an electrical signal using an optical system and a drive unit like a scanner in a line sensor, and optically converts optical image information like an imaging module in a two-dimensional sensor. The system functions as an image sensor by forming an image on a sensor and converting it into an electrical signal.
Since the photovoltaic cell is a power generation device, the efficiency of converting light energy into electrical energy is an important performance, but dark current, which is a current in a dark place, is not a functional problem. Further, a subsequent heating step such as installation of a color filter is not necessary. Since it is important to convert light and dark signals into electrical signals with high accuracy, the efficiency of converting light intensity into current is also important for optical sensors. Low dark current is required. In addition, resistance to subsequent processes is also important.

[Image sensor]
Next, a configuration example of an image sensor including the photoelectric conversion element 10a will be described.
In the configuration examples described below, members having the same configuration / action as those already described are denoted by the same or corresponding reference numerals in the drawings, and the description is simplified or omitted.
An image sensor is an element that converts optical information of an image into an electric signal. A plurality of photoelectric conversion elements are arranged on a matrix in the same plane, and an optical signal is converted into an electric signal in each photoelectric conversion element (pixel). That can be output to the outside of the imaging device for each pixel sequentially. Therefore, one pixel is composed of one photoelectric conversion element and one or more transistors.
FIG. 2 is a schematic cross-sectional view showing a schematic configuration of an image sensor for explaining an embodiment of the present invention. This imaging device is used by being mounted on an imaging device such as a digital camera or a digital video camera, an imaging module such as an electronic endoscope or a mobile phone, or the like.
This imaging element has a plurality of photoelectric conversion elements having the configuration shown in FIG. 1 and a circuit board on which a readout circuit for reading a signal corresponding to the charge generated in the photoelectric conversion film of each photoelectric conversion element is formed. A plurality of photoelectric conversion elements are arranged one-dimensionally or two-dimensionally on the same surface above the circuit board.

  2 includes a substrate 101, an insulating layer 102, a connection electrode 103, a pixel electrode (lower electrode) 104, a connection portion 105, a connection portion 106, a photoelectric conversion film 107, and a counter electrode. (Upper electrode) 108, buffer layer 109, sealing layer 110, color filter (CF) 111, partition 112, light shielding layer 113, protective layer 114, counter electrode voltage supply 115, and readout circuit 116.

  The pixel electrode 104 has the same function as the lower electrode 11 of the photoelectric conversion element 10a shown in FIG. The counter electrode 108 has the same function as the upper electrode 15 of the photoelectric conversion element 10a shown in FIG. The photoelectric conversion film 107 has the same configuration as the layer provided between the lower electrode 11 and the upper electrode 15 of the photoelectric conversion element 10a illustrated in FIG.

  The substrate 101 is a glass substrate or a semiconductor substrate such as Si. An insulating layer 102 is formed on the substrate 101. A plurality of pixel electrodes 104 and a plurality of connection electrodes 103 are formed on the surface of the insulating layer 102.

  The photoelectric conversion film 107 is a layer common to all the photoelectric conversion elements provided on the plurality of pixel electrodes 104 so as to cover them.

  The counter electrode 108 is one electrode provided on the photoelectric conversion film 107 and common to all the photoelectric conversion elements. The counter electrode 108 is formed up to the connection electrode 103 disposed outside the photoelectric conversion film 107, and is electrically connected to the connection electrode 103.

  The connection part 106 is embedded in the insulating layer 102 and is a plug or the like for electrically connecting the connection electrode 103 and the counter electrode voltage supply part 115. The counter electrode voltage supply unit 115 is formed on the substrate 101 and applies a predetermined voltage to the counter electrode 108 via the connection unit 106 and the connection electrode 103. When the voltage to be applied to the counter electrode 108 is higher than the power supply voltage of the image sensor, the power supply voltage is boosted by a booster circuit such as a charge pump to supply the predetermined voltage.

  The readout circuit 116 is provided on the substrate 101 corresponding to each of the plurality of pixel electrodes 104, and reads out a signal corresponding to the charge collected by the corresponding pixel electrode 104. The readout circuit 116 is configured by, for example, a CCD, a CMOS circuit, a TFT circuit, or the like, and is shielded by a light shielding layer (not shown) disposed in the insulating layer 102. The readout circuit 116 is electrically connected to the corresponding pixel electrode 104 via the connection unit 105.

  The buffer layer 109 is formed on the counter electrode 108 so as to cover the counter electrode 108. The sealing layer 110 is formed on the buffer layer 109 so as to cover the buffer layer 109. The color filter 111 is formed at a position facing each pixel electrode 104 on the sealing layer 110. The partition wall 112 is provided between the color filters 111 and is for improving the light transmission efficiency of the color filter 111.

  The light shielding layer 113 is formed in a region other than the region where the color filter 111 and the partition 112 are provided on the sealing layer 110, and prevents light from entering the photoelectric conversion film 107 formed outside the effective pixel region. The protective layer 114 is formed on the color filter 111, the partition 112, and the light shielding layer 113, and protects the entire image sensor 100.

  In the imaging device 100 configured as described above, when light is incident, the light is incident on the photoelectric conversion film 107, and charges are generated here. Holes in the generated charges are collected by the pixel electrode 104, and a voltage signal corresponding to the amount is output to the outside of the image sensor 100 by the readout circuit 116.

The manufacturing method of the image sensor 100 is as follows.
On the circuit board on which the common electrode voltage supply unit 115 and the readout circuit 116 are formed, the connection units 105 and 106, the plurality of connection electrodes 103, the plurality of pixel electrodes 104, and the insulating layer 102 are formed. The plurality of pixel electrodes 104 are arranged on the surface of the insulating layer 102 in a square lattice pattern, for example.

  Next, the photoelectric conversion film 107 is formed on the plurality of pixel electrodes 104 by, for example, a vacuum heating deposition method. Next, the counter electrode 108 is formed on the photoelectric conversion film 107 under vacuum by, for example, sputtering. Next, the buffer layer 109 and the sealing layer 110 are sequentially formed on the counter electrode 108 by, for example, a vacuum heating deposition method. Next, after forming the color filter 111, the partition 112, and the light shielding layer 113, the protective layer 114 is formed, and the imaging element 100 is completed.

  Even in the method of manufacturing the image sensor 100, a plurality of processes can be performed even when a step of placing the image sensor 100 being manufactured under non-vacuum is added between the process of forming the photoelectric conversion film 107 and the process of forming the sealing layer 110. The performance deterioration of the photoelectric conversion element can be prevented. By adding this step, it is possible to suppress the manufacturing cost while preventing the performance degradation of the image sensor 100.

  Examples are shown below, but the present invention is not limited thereto.

(Synthesis of Compound D3)

  To a 100 mL three-necked round bottom flask, 5.46 g (30 mmol) of p-bromobenzonitrile, 20 mL of t-amyl alcohol, and 5.05 g (45 mmol) of potassium t-butoxide were added and heated to 95 ° C. with stirring. To this mixture, a solution of 2.73 g (13.5 mmol) of diisopropyl succinate in 3 mL of t-amyl alcohol was added dropwise over 25 minutes. After the addition, the reaction mixture was heated to reflux for 4 hours and then cooled to 50 ° C. To this mixture, 15 mL of water and 15 mL of methanol were added, stirred for 30 minutes, and the precipitate was collected by filtration. The obtained red powder was washed with 50% aqueous methanol and water and vacuum dried at 80 ° C. to obtain 3.0 g (yield 50%) of Compound 1 as a red powder.

  Compound 1 (1.0 g, 2.24 mmol), potassium carbonate 1.24 g (8.97 mmol) and N-methylpyrrolidone 35 mL were added to a 200 mL three-necked round bottom flask, and the mixture was stirred at room temperature for 30 minutes under a nitrogen atmosphere. Next, 4.07 g (28.7 mmol) of iodomethane was added and stirred at room temperature for 1 hour. Further, 3.18 g (22.4 mmol) of iodomethane was added, heated to 55 ° C., and stirred for 5 hours. After cooling to room temperature, 100 mL of water was added, and the resulting solid was collected by filtration. The product was purified by silica gel column chromatography to obtain Compound 2 as an orange powder in 319 mg (yield 30%).

Compound 2 (0.3 g, 0.63 mmol), 50 mg of Pd ₂ (dba) ₃ , ₃₀ mg of DPPF, and 15 mL of xylene were added to a 100 mL three-necked round bottom flask and stirred at room temperature for 15 minutes under a nitrogen atmosphere. Diphenylamine 0.32 g (1.89 mmol) and sodium t-butoxide 0.9 g (9.45 mmol) were added, and the mixture was stirred at 100 ° C. for 7 hours, and then cooled to room temperature. Water and ethyl acetate were added to the reaction mixture, the organic layer was extracted, and the solvent was distilled off. Purification by silica gel column chromatography gave 0.26 g (64% yield) of D3 as a reddish brown powder.

In addition, the compounds D1 to D2 and D4 to D14 described later were synthesized with reference to the synthesis method of the compound D3 and known methods.
The compounds (D1 to D14, RD1 to RD4) used in the examples and comparative examples are collectively shown below.

<Production of photoelectric conversion element>
A photoelectric conversion element having the configuration shown in FIG. Here, the photoelectric conversion element includes the lower electrode 11, the electron blocking film 16 </ b> A, the photoelectric conversion film 12, and the upper electrode 15.
Specifically, an amorphous ITO film is formed on a glass substrate by sputtering to form the lower electrode 11 (thickness: 30 nm), and the following compound (EB-1) is vacuum heated on the lower electrode 11. An electron blocking film 16A (thickness: 100 nm) was formed by vapor deposition. Furthermore, with the substrate temperature controlled at 25 ° C., the above compounds (D1 to D14, RD1 to RD4) and fullerene (C ₆₀ ) are 100 nm and 300 nm in terms of a single layer, respectively, on the electron blocking film 16A. Thus, a film was formed by co-evaporation by vacuum heating evaporation to form a photoelectric conversion film 12. Further, an amorphous ITO film was formed on the photoelectric conversion film 12 by sputtering to form an upper electrode 15 (transparent conductive film) (thickness: 10 nm). An SiO film was formed as a sealing layer on the upper electrode 15 by heating vapor deposition, and then an aluminum oxide (Al ₂ O ₃ ) layer was formed thereon by ALCVD to produce a photoelectric conversion element.

<Element heat resistance>
Each element obtained was thermally annealed by holding it on a hot plate at 150 ° C. for 20 minutes under a nitrogen atmosphere, and after returning to room temperature, the dark current was measured and the rate of increase in dark current from before the annealing [{ (A dark current value after annealing−dark current value before annealing) / dark current value before annealing} × 100 (%)] was less than 5%, “A”, 5% or more and less than 10% The result was listed as “B” and “C” in the “Heat resistance” column of Table 1 as “C”. In practice, it must be A or B.

<Evaluation of response speed (98% signal rise time)>
The relative response speed (rising time from 0 to 98% signal intensity) when an electric field of 2 × 10 ⁵ V / cm was applied to the photoelectric conversion element in the obtained solid-state imaging device was measured. It was calculated as a relative value and described in the “response speed (relative value)” column of Table 1. In the measurement of the photoelectric conversion performance of each element, light was incident from the upper electrode (transparent conductive film) side. The method for obtaining the relative value is shown below.
(Relative value with Example 1 as 1)
= [Rise Time from 0 to 98% Signal Strength in Example (or Comparative Example) X] / [Rise Time from 0 to 98% Signal Strength in Example 1]
In practice, it is preferably within 20 and more preferably within 5.

As shown in Table 1 above, it was confirmed that the photoelectric conversion element of the present invention exhibits excellent heat resistance and responsiveness.
For example, as can be seen from the comparison of Examples 1 to 14, Ar ¹ and R ¹¹ , Ar ¹ and R ¹² , R ¹¹ and R ¹² , Ar ² and R ¹³ , Ar ² and R ¹⁴ , and R ¹³ and R ¹⁴ It was confirmed that the heat resistance was more excellent when at least one of these bonded to each other to form a ring.
Further, as can be seen from the comparison between Example 1 and Example 5, at least one of Ar ¹ and R ¹¹ , Ar ¹ and R ^12, and R ¹¹ and R ¹² in the general formulas (1) to (3). Are bonded to each other to form a ring, and Ar ² and R ¹³ , Ar ² and R ¹⁴ , and R ¹³ and R ¹⁴ are bonded to each other to form a ring (corresponding to Example 1). It was confirmed that the responsiveness was more excellent.
As can be seen from the comparison between Example 4 and Example 6, Ar ¹ and R ¹¹ , Ar ¹ and R ¹² , R ¹¹ and R ¹² , Ar ² and R ¹³ , Ar ² and R ¹⁴ , R ¹³ and It was confirmed that R ¹⁴ was more excellent in responsiveness when bonded directly without a linking group (corresponding to Example 6).
Further, as can be seen from the comparison between Example 3 and Example 7, when X ¹ and X ² are O (oxygen atoms) (corresponding to Example 3), it was confirmed that the response speed and the heat resistance were more excellent. It was.
Further, as can be seen from the comparison between Example 1 and Example 8, it was confirmed that when Ar ¹ and Ar ² are an arylene group (corresponding to Example 1), the responsiveness is more excellent.

On the other hand, when RD1 used in the Example column of Patent Document 1 was used (corresponding to Comparative Example 1), it was confirmed that the heat resistance and responsiveness were inferior.
Also, formulas (1) to (3) (corresponding to Comparative Example 2) When using the R ¹ and R ² are hydrogen atoms RD2 in, it was confirmed that the poor responsiveness.
Furthermore, when RD3 whose R < ¹¹ > -R < ¹⁴ > in General formula (1)-General formula (3) is an alkyl group was used (corresponding to the comparative example 3), it was confirmed that it is inferior in responsiveness.
Moreover, when RD4 which does not have an amino group was used (corresponding to Comparative Example 4), the compound was originally decomposed during vapor deposition, and a photoelectric conversion film could not be produced.
RD2 and RD3 correspond to the exemplified compounds (19) and (71) exemplified in JP2010-192882A, and RD4 is used in Example 6 of JP2003-346926A. Corresponds to the compound.

<Production of image sensor>
An image sensor similar to that shown in FIG. 2 was produced. That is, after depositing amorphous TiN 30 nm on the CMOS substrate by sputtering, patterning is performed by photolithography so that one pixel exists on each photodiode (PD) on the CMOS substrate to form the lower electrode. Thereafter, the electron blocking material was formed in the same manner as in Examples 1 to 14 and Comparative Examples 1 to 4. The evaluation was performed in the same manner, and the same results as in Table 1 were obtained. It was found that the imaging element is suitable for manufacturing and exhibits excellent performance.

10a, 10b Photoelectric conversion element 11 Lower electrode (conductive film)
12 Photoelectric conversion film 15 Upper electrode (transparent conductive film)
16A Electron blocking film 16B Hole blocking film 100 Image sensor 101 Substrate 102 Insulating layer 103 Connection electrode 104 Pixel electrode (lower electrode)
105 connecting portion 106 connecting portion 107 photoelectric conversion film 108 counter electrode (upper electrode)
109 Buffer layer 110 Sealing layer 111 Color filter (CF)
112 partition wall 113 light shielding layer 114 protective layer 115 counter electrode voltage supply unit 116 readout circuit

Claims (8)

A photoelectric conversion element formed by laminating a conductive film, a photoelectric conversion film containing a photoelectric conversion material, and a transparent conductive film in this order,
The photoelectric conversion material is at least one selected from the group consisting of a compound represented by the general formula (1), a compound represented by the general formula (2), and a compound represented by the general formula (3). compound X seen including,
The photoelectric conversion element in which the said photoelectric conversion film contains an organic n-type compound further .
(In the general formulas (1) to (3), R ¹ and R ² each independently represents an alkyl group, an aryl group, or a heteroaryl group. R ¹¹ , R ¹² , R ^13, and R ¹⁴ are independently .Ar ¹ and Ar ² represents an alkyl group, an aryl group or heteroaryl group, each independently, represent an a arylene group or a heteroarylene group. Note that at least one of R ¹¹ and R ^12, and, At least one of R ¹³ and R ¹⁴ represents an aryl group or a heteroaryl group, X ¹ and X ² each independently represent O, S, or NR ^A , R ^A represents an alkyl group, an aryl group, Or Q represents a group selected from the group consisting of general formula (A) to general formula (E), and R ^{01 to} R ⁰²² each independently represents a hydrogen atom or a substituent. Group To .n represents 0 or 1.
However, Ar ¹ and R ^11, Ar ¹ and R ^12, R ¹¹ and R ^12, Ar ² and R ^13, Ar ² and R ^14, and, at least one is bonded to each other rings of R ¹³ and R ¹⁴ formation to. )
The photoelectric conversion element of Claim 1 whose said compound X is a compound represented by General formula (4).
(In General Formula (4), R ¹ and R ² each independently represents an alkyl group, an aryl group, or a heteroaryl group. R ¹¹ , R ¹² , R ^13, and R ¹⁴ are each independently .Ar ¹ and Ar ² represents an alkyl group, an aryl group or heteroaryl group, each independently, represent an a arylene group or a heteroarylene group. Note that at least one of R ¹¹ and R ^12, and, R ¹³ and R ^At least one of ¹⁴ represents an aryl group or a heteroaryl group, X ¹ and X ² each independently represent O, S, or NR ^A. R ^A represents an alkyl group, an aryl group, or a heteroaryl group Represents.
However, Ar ¹ and R ^11, Ar ¹ and R ^12, R ¹¹ and R ^12, Ar ² and R ^13, Ar ² and R ^14, and, at least one is bonded to each other rings of R ¹³ and R ¹⁴ formation to. ) The photoelectric conversion element according to claim 1, wherein X ¹ and X ² are O. The photoelectric conversion element of any one of Claims 1-3 in which the said organic n-type compound contains fullerene selected from the group which consists of fullerene and its derivative (s) . The photoelectric conversion element according to claim 4 , wherein a molar ratio of the compound X to the fullerene (molar amount of the fullerene / molar amount of the compound X) is 1.0 or more. The charge blocking layer between the conductive film and the transparent conductive layer is disposed, the photoelectric conversion device according to any one of claims 1-5. The image pick-up element containing the photoelectric conversion element of any one of Claims 1-6 . Light sensor comprising a photoelectric conversion device according to any one of claims 1-7.