JP5981399B2 - ORGANIC MATERIAL FOR FILM FORMATION, ORGANIC PHOTOELECTRIC CONVERSION DEVICE, IMAGING ELEMENT, LIGHT RECEIVING LAYER FORMING METHOD, AND ORGANIC PHOTOELECTRIC CONVERSION METHOD - Google Patents

Description

The present invention relates to an organic material for film formation used for dry film formation of an organic photoelectric conversion element, and an organic photoelectric conversion element, an imaging element, and an organic electroluminescence element obtained using the same. The present invention also relates to a method for forming a light receiving layer constituting an organic photoelectric conversion element and a method for manufacturing the organic photoelectric conversion element.

  Lightweight, large area, high flexibility, organic photoelectric conversion film with features that can be manufactured by printing process, and organic photoelectric conversion element equipped with it is an image sensor (imaging element) used for digital cameras etc. In addition, it is expected to be used in various applications such as organic electroluminescent elements (organic EL) used for displays and lighting, organic thin film solar cells and organic thin film transistors used for electronic paper, and the like.

  In recent years, in the field of image sensors, the area of the photodiode section has become smaller as the pixel size has been reduced due to the increase in the number of pixels of the image sensor, resulting in a decrease in aperture ratio and light condensing efficiency and accompanying sensitivity reduction. It has become. In general, as an image sensor, a planar light-receiving element that performs photoelectric transfer and readout of signals generated by photoelectric conversion in each pixel by a CCD circuit or a CMOS circuit as a pixel by two-dimensionally arranging photoelectric conversion sites in a semiconductor Is widely used.

  In addition to the features described above, the organic imaging device is expected because a high aperture ratio can be obtained compared to a conventional photoelectric conversion site in which a photodiode portion using a PN junction is formed in a semiconductor such as Si. It is growing.

  Organic thin-film solar cells are widely studied due to the advantages of easy manufacturing process and large area at low cost compared to inorganic solar cells typified by silicon, but low energy conversion efficiency. It has not yet reached a practical level.

  Organic electroluminescence (EL) elements are attracting attention as display elements and light-emitting elements because they can emit light with high luminance at a low voltage. Organic EL elements can be greatly reduced in power consumption, easily reduced in size, and increased in area, and research into practical use has been actively conducted as next-generation display elements and light-emitting elements.

  The present applicant has repeatedly studied an organic photoelectric conversion element including an organic layer in a light-receiving layer or a light-emitting layer, and an imaging element, an optical sensor, a solar cell, and an organic electroluminescence element including the organic photoelectric conversion element. In order to realize a high S / N ratio in an organic photoelectric conversion element, it is necessary to have high photoelectric conversion efficiency and low dark current performance.

  For example, in order to improve the photoelectric conversion efficiency in the light receiving element, it is preferable that exciton dissociation efficiency in the light receiving layer is good and charge transportability is good. Moreover, when using as optical sensors, such as an image pick-up element, it is necessary to suppress a dark current and it is preferable that the carrier amount at the time of darkness can be controlled. Moreover, it is necessary to satisfy high-speed signal response.

  For the purpose of improving the performance of the organic photoelectric conversion element, the applicant of the present invention has a mixed layer of a p-type organic semiconductor and fullerene or a fullerene derivative (a bulk heterostructure in which two materials are co-evaporated). An organic photoelectric conversion element using a layer) has been filed (Patent Document 1).

JP 2007-123707 A

  According to Patent Document 1, an organic photoelectric conversion element having high photoelectric conversion efficiency and a favorable photocurrent / dark current S / N ratio can be provided. For film formation of the light receiving layer of the organic photoelectric conversion element described in Patent Document 1, mainly dry film formation such as vapor deposition is preferably used. In dry film formation, film formation is performed using a film formation material containing a constituent material such as a vapor deposition source or a sputtering target, and it is preferable to use a material having high purity as the film formation material.

  The purity of the film forming material is generally evaluated by high performance liquid chromatography (HPLC). Therefore, it is common to use a film-forming material having an HPLC purity close to 100%. As a film-forming material for the light-receiving layer of the organic photoelectric conversion element, a dry composition having an HPLC purity of 95% or more, preferably 98% or more. If a film organic material is used, it is considered that the influence on the film characteristics caused by the film forming material is negligible.

  In the film formation of the light receiving layer (photoelectric conversion layer, electron blocking layer, hole blocking layer, etc.) of the organic photoelectric conversion element described in Patent Document 1, the present inventors have formed a film having an HPLC purity of 95% or more. The light-receiving layer is formed using the material for use. However, the present inventor has confirmed the phenomenon that pixel defects vary even when organic materials for film formation having the same HPLC purity are used. This phenomenon is confirmed in the same manner even when a film-forming organic material having an HPLC purity of 100% is used.

  A pixel defect is a defect that causes a decrease in sensitivity of several pixels called white scratches or black scratches in a photoelectric conversion element used in an optical sensor such as an image sensor, and is a substance (foreign matter) that can be a defect in the light receiving layer. ) Is thought to be the cause. If a foreign substance larger than the pixel is mixed, it becomes a defect extending to a plurality of pixels, and correction is impossible. In particular, the influence is great in optical sensor applications in which the length of the long side of one pixel is 5 μm or less, such as an image sensor.

  The present invention has been made in view of the above circumstances, and in the production of an organic photoelectric conversion element used in an optical sensor, stably forming a light-receiving layer with little mixing of substances that can cause pixel defects, and An object of the present invention is to provide an organic material for film formation that makes it possible.

  Another object of the present invention is to stably manufacture an organic photoelectric conversion element with few pixel defects in an organic photoelectric conversion element used in an optical sensor.

  In order to stably manufacture an organic photoelectric conversion element having high photoelectric conversion efficiency, good photocurrent / dark current S / N ratio, and high response speed, In the organic material for film formation such as the light-receiving layer, it was found that the residual solvent remained in the organic material for film formation and was considered to be negligible in terms of HPLC purity. Japanese Patent Application No. 2012-164658 (unpublished at the time of filing) which disclosed that the residual solvent was 3 mol% or less was filed.

  However, even when the organic material for film formation of Japanese Patent Application No. 2012-164658 is used, there remains a problem of stably forming a light receiving layer with few pixel defects.

  Regarding pixel defects, as described in Japanese Patent Application No. 2011-162003 (not disclosed at the time of filing), the present inventors are caused by the presence of metals and halogen elements that were considered to be negligible in terms of HPLC purity. In other words, in the organic material for film formation with high HPLC purity, it has been found that the metal content is preferably less than 10 ppm, and the halogen element is preferably less than 100 ppm. In addition to trace amounts of metals and halogen elements, the inventors have found that substances that adversely affect pixel defects are mixed in, and the present invention has been completed.

  That is, the organic material for film formation of the present invention is used for dry film formation of a light receiving layer of an organic photoelectric conversion element used in an optical sensor, and is a film forming organic material mainly composed of organic substances constituting the light receiving layer. , Containing less than 1.0% by mass of a substance that cannot be detected by high performance liquid chromatography (hereinafter referred to as HPLC).

The light-receiving layer forming method of the present invention is a method of forming a light-receiving layer of an organic photoelectric conversion element used in an optical sensor by a dry film forming method, and is composed of a constituent organic substance of the light-receiving layer as a main component and measured by HPLC. Preparing a film-forming organic material having a purity of 98% or more and a metal content of 10 ppm or less;
A purification step for removing a substance that cannot be detected by HPLC measurement from the organic material for film formation so that the content of the substance in the organic material for film formation is less than 1.0% by mass;
And a film forming step of forming a light receiving layer by a dry film forming method using the organic material for film formation after the purification step. Such a method is preferably used for forming a light receiving layer in a method of manufacturing an organic photoelectric conversion element having a pair of electrodes and a light receiving layer or a light emitting layer including at least a photoelectric conversion layer sandwiched between the pair of electrodes. it can.

  In the present specification, the “constituent organic substance” means all organic substances excluding inevitable impurities and substances unintentionally contained in the organic material for film formation among the organic substances contained in the organic material for film formation. To do.

  In this specification, “substances that cannot be detected by HPLC measurement” means substances that remain on the filter after the filtration operation after being completely dissolved (judged by visual inspection) in the solvent used for HPLC detection. To do.

  In this specification, the content of a substance that cannot be detected by HPLC measurement is obtained by filtering a solution obtained by completely dissolving (determining visually) an organic material for film formation into a solvent using a membrane filter having a pore size of 1 μm or less. The value calculated from the mass of the substance remaining on the top.

  In this specification, the “purity of the organic material for film formation” means that the organic material for film formation is dissolved in a solvent and is suitable for HPLC using a UV / VIS (190 nm to 900 nm) detector. The absorbance is monitored by wavelength, and the peak area ratio of the main component of the constituent organic matter is obtained.

In the organic material for film formation and the light-receiving layer forming method of the present invention, the substances that cannot be detected by HPLC include substances generated by the reaction of constituent organic substances and / or metals, intermediates generated in the manufacturing process of constituent organic substances, and There may be mentioned at least one of substances produced by the reaction of this intermediate.

  The present invention can be suitably used for forming a light receiving layer of an optical sensor in which the length of the longer side of one pixel is 5 μm or less.

  In the present invention, the content of a substance that cannot be detected by HPLC is preferably 0.8% by mass or less, and more preferably 0.5% by mass or less.

  The present invention is suitable when the substance that cannot be detected by HPLC has a higher sublimation temperature than the constituent organic substances.

In the present specification, “the sublimation temperature is higher than that of the constituent organic substance” means that the sublimation pressure at a vacuum degree of 1 × 10 ⁻³ Pa or less is higher than the sublimation pressure of the constituent organic substance.

  In the present invention, the amount of each metal not contained in the constituent organic matter is preferably less than 10 ppm.

  In the present invention, the amount of residual solvent in the organic material for film formation is preferably 3 mol% or less.

  In the present invention, examples of suitable organic materials include fullerene or fullerene derivatives.

  As a dry film forming method suitable for the film forming organic material of the present invention, a vacuum resistance heating vapor deposition method may be mentioned.

  Examples of the light receiving layer include a photoelectric conversion layer, an electron blocking layer, and a hole blocking layer, and the present invention is particularly suitable for forming a photoelectric conversion layer and an electron blocking layer.

  The organic photoelectric conversion element of the present invention is an organic photoelectric conversion element having a pair of electrodes and a light receiving layer including at least the photoelectric conversion layer sandwiched between the pair of electrodes, at least one of the pair of electrodes being a transparent electrode The light-receiving layer includes a layer formed by dry film formation using the film-forming organic material of the present invention. A device including a plurality of organic photoelectric conversion elements and a circuit board on which a signal reading circuit that reads a signal corresponding to the electric charge generated in the photoelectric conversion layer of the photoelectric conversion element is formed is suitable as an optical sensor or an imaging element.

  The organic material for film formation according to the present invention is an organic material for film formation mainly composed of organic substances constituting the light receiving layer of an organic photoelectric conversion element used in an optical sensor, and has a high purity as evaluated by HPLC. Inclusion of substances remaining in organic materials and produced by reaction of constituent organic substances and / or metals, intermediates produced in the production process of constituent organic substances, and substances produced by reaction of these intermediates The amount is less than 1.0% by mass. By using such an organic material for film formation, it is possible to stably form a light-receiving layer with less mixing of substances that may cause pixel defects, and to stably manufacture organic photoelectric conversion elements with few pixel defects. it can.

Schematic cross-sectional schematic diagram showing an embodiment of the organic photoelectric conversion device of the present invention Schematic perspective view (vacuum heating vapor deposition) showing vapor deposition method of light receiving layer 1 is a schematic cross-sectional schematic diagram illustrating an embodiment of an image sensor according to the present invention.

"Organic materials for film formation, light-receiving layer formation method , photoelectric conversion element"
With reference to drawings, the photoelectric conversion element of one Embodiment concerning this invention is demonstrated. FIG. 1 is a schematic cross-sectional view showing the configuration of the photoelectric conversion element of this embodiment. In the drawings of this specification, the scale of each part is appropriately changed and shown for easy visual recognition.

  As shown in FIG. 1, the organic photoelectric conversion element 1 (photoelectric conversion element 1) includes a substrate 10, a lower electrode 20 formed on the substrate 10, an electron blocking layer 31 formed on the lower electrode 20, and , An organic photoelectric conversion layer (hereinafter referred to as a photoelectric conversion layer) 32 formed on the electron blocking layer 31, an electrode 40 formed on the photoelectric conversion layer 32, and a sealing layer 50 formed on the electrode 40. With. A light receiving layer 30 is formed by the electron blocking layer 31 and the photoelectric conversion layer 32. The light receiving layer 30 may be a layer including at least the photoelectric conversion layer 32, and may be a layer including a layer other than the electron blocking layer 31 (for example, a hole blocking layer).

  The electron blocking layer 31 included in the light receiving layer 30 suppresses the injection of electrons from the lower electrode 20 into the photoelectric conversion layer 32 and inhibits the electrons generated in the photoelectric conversion layer 32 from flowing to the electrode 20 side. Layer. The electron blocking layer 31 includes an organic material, an inorganic material, or both.

  The electrode 40 is an electrode that collects electrons out of the charges generated in the photoelectric conversion layer 32. The electrode 40 is made of a conductive material (for example, ITO) that is sufficiently transparent to light having a wavelength with which the photoelectric conversion layer 32 has sensitivity in order to cause light to enter the photoelectric conversion layer 32. By applying a bias voltage between the electrode 40 and the electrode 20, among the charges generated in the photoelectric conversion layer 32, holes can be moved to the electrode 20 and electrons can be moved to the electrode 40.

  The photoelectric conversion element 1 configured as described above uses the upper electrode 40 as a light incident side electrode, and when light is incident from above the upper electrode 40, this light is transmitted through the upper electrode 40 and incident on the photoelectric conversion layer 32. Here, charges are generated. Holes in the generated charges move to the lower electrode 20. By converting the holes transferred to the lower electrode 20 into a voltage signal corresponding to the amount of the holes and reading out the light, the light can be converted into a voltage signal and extracted.

  Further, a bias voltage may be applied so as to collect electrons at the electrode 20 and collect holes at the electrode 40. In this case, a hole blocking layer may be provided instead of the electron blocking layer 31. The hole blocking layer suppresses injection of holes from the electrode 20 into the photoelectric conversion layer 32, and an organic material for inhibiting holes generated in the photoelectric conversion layer 32 from flowing toward the electrode 20 side. It may be a layer composed of In either case, the portion sandwiched between the electrode 20 and the electrode 40 becomes the light receiving layer 30.

  In the photoelectric conversion element 1, the light receiving layer 30 including the photoelectric conversion layer 32 is a layer (organic layer) including an organic material, and is an organic film formed by a dry film forming method using the film forming organic material 60. Including layers.

  The dry film forming method is not particularly limited, and examples thereof include physical vapor deposition, sputtering, and chemical vapor deposition, but vacuum resistance vapor deposition can be preferably used.

  FIG. 2 shows an example of a schematic diagram showing a state of film formation by vacuum resistance heating vapor deposition. As shown in FIG. 2, the light-receiving layer is normally vapor-deposited with a substrate holder 90 provided above the opening of the vapor deposition cell 71 installed in the vapor deposition chamber 91, and with the substrate B installed in the holder 90. Do. In the vapor deposition cell 71 having a heating function, a film-forming organic material (vapor deposition material) 60 is installed, and since the inside of the vapor deposition chamber 91 has a high degree of vacuum, the vapor deposition material evaporated from the vapor deposition cell 71 has an opening portion. The film is emitted from the substrate and travels straight and is formed on the substrate B. By adjusting the opening diameter of the opening of the vapor deposition cell 71, the maximum emission angle θ of the evaporated vapor deposition material can be adjusted.

  The vapor deposition cell 71 and the substrate B are preferably separated by 10 cm or more if possible. The evaporated deposition material is incident on the substrate surface while spreading in a substantially conical shape at an incident angle of 0 ° to θ.

  The organic material 60 for film formation is installed as a vapor deposition source having a shape such as a boat type, a basket type, a hairpin type, or a crucible type, and is not particularly limited.

  As the film-forming organic material 60, a high-purity film-forming organic material having an HPLC purity of 95% or higher, preferably 98% or higher is usually used. Hereinafter, the high-purity organic material for film-forming shall mean the organic material for film-forming whose HPLC purity is 95% or more.

  The present inventor has investigated the cause of variation in the amount of substances that can cause pixel defects mixed in the light-receiving layer even when the light-receiving layer is formed using a high-purity organic material for film formation. Went. As a result, the organic material for film formation includes, in addition to inevitable impurities, substances generated by reactions such as decomposition and polymerization of constituent organic substances and / or metals, intermediates produced in the manufacturing process of constituent organic substances, and intermediates thereof. Substances produced by reactions such as decomposition or polymerization of the body are mixed, and some of these substances (hereinafter sometimes referred to as foreign substances causing pixel defects) cannot be detected by HPLC It has been found that even in a high-purity organic material for film formation, the organic material is contained at a content rate that can be a pixel defect (the present inventor believes that it is 1.0% by mass or more).

  The present inventor found that even if such a substance is a substance having a sublimation temperature higher than that of the constituent organic substance, the substance is entrained and sublimated during sublimation of the constituent organic substance. I think that will cause.

  For example, in a film-forming organic material mainly composed of fullerenes or fullerene derivatives (hereinafter sometimes referred to as fullerenes), when amorphous carbon formed by polymerization of fullerenes is contained, amorphous carbon is used for HPLC measurement. Since some materials are hardly soluble in the solvent to be used and cannot be detected by HPLC, even if the material is contained in several percent or more, it is used as a high-purity organic material for film formation without being removed as it is. Further, although the sublimation temperature of amorphous carbon is higher than that of fullerenes, the present inventor believes that it is likely to cause pixel defects because it is easily caught in fullerenes during sublimation of fullerenes.

  Based on such knowledge, the high-purity organic material for film formation is further refined, and the content of foreign matter causing pixel defects is less than 1.0% by mass, preferably 0.8% by mass or less, more preferably 0%. It was found that a light-receiving layer having few pixel defects can be stably formed by forming a light-receiving layer after carrying out a step (purification step) of 0.5 mass% or less.

Therefore, the dry film formation of the light receiving layer 30 of the organic photoelectric conversion element 1 has a constituent organic substance of the light receiving layer 30 as a main component, a purity measured by HPLC of 98% or more, and a metal content of 10 ppm or less. Preparing a high-purity organic material for film formation (A),
From this high-purity organic material for film formation, a foreign substance that causes pixel defects that cannot be detected by HPLC measurement, and the content of the foreign material in the organic material for film formation is less than 1.0% by mass (B )When,
This is performed by a method including a film forming step (C) in which the light receiving layer 30 is formed by a dry film forming method using the organic material 60 for film formation after the purification step (B).

  The method for removing foreign substances that cause pixel defects is not particularly limited. For example, a high-purity organic material for film formation is completely dissolved in a solvent in which decomposition of the material is not accelerated during melting, and a membrane having a pore size of 0.1 μm to 1 μm Foreign matters can be removed by suction filtration with a filter and removing the solvent by concentrating the filtrate under reduced pressure.

The solvent used in the HPLC detection is appropriately changed depending on the constituent organic substances, and the type thereof is not limited.
Two or more kinds of solvents may be mixed. For example, isooctane, n-hexane, n-heptane, diethyl ether, cyclohexane, ethyl acetate, toluene, chloroform, THF, benzene, acetone, dichloromethane, dioxane, propanol, ethanol, dimethylformamide, acetonitrile, acetic acid, methanol, dimethyl sulfoxide, Examples include tetrachloromethane, dichlorobenzene, dichloroethane, trichlorobenzene, hexafluoroisopropanol, DMI, N-methylpyrrolidone, N-ethylpyrrolidone, water, or a mixture of two or more of these, but limited to the above solvents Not.

  In addition, the high-purity organic material for film formation may include a solvent that remains undetectable by HPLC. Since this solvent affects characteristics such as photoelectric conversion efficiency, photocurrent / dark current S / N ratio, and response speed, a solvent removal step of 3 mol% or less of residual solvent is performed in the purification step. It is preferable to do.

  The mechanism by which the residual solvent affects these properties is not clear, but the present inventor has shown that the residual solvent, which is slightly contained, increases the thermal load because decomposition is accelerated by the thermal load or over time. When the residual solvent reacts with the organic substance, the organic substance has an adverse effect such as partial decomposition, and the organic substance is sublimated to form a film, so that deterioration of the film characteristics is observed over time. I guess. In high-purity organic materials for film formation, the remaining solvent that cannot be detected by HPLC is 3 mol% or less, so that a photoelectric conversion element with a fast response speed can be stabilized while maintaining good photoelectric conversion efficiency and S / N ratio. Can be manufactured.

  The type of residual solvent is not limited, although the amount of influence is large or small. Examples of the solvent include water, alcohols, ethers, ketones, sulfoxides, carbonates, amides, carboxylic acids, esters, nitriles, halogens, aromatics and the like. More specifically, when two or more types of solvents are contained, the total content of the two or more types is preferably 3 mol% or less.

  Specific examples of solvents that may remain include methanol, ethanol, propanol, isopropanol, butanol, isobutanol, t-butyl alcohol, ethylene glycol, propylene glycol, glycerin, dimethyl ether, diethyl ether, 1,2-dimethoxyethane. , Diglyme, triglyme, oligoethylene oxide, oligopropylene oxide, polyethylene oxide, polypropylene oxide, anisole, diphenyl ether, THF, dioxane, 1,3-dioxolane, acetone, MEK, cyclohexanone, cyclopentanone, dimethyl sulfoxide, dimethyl sulfone, sulfolane , Dimethyl carbonate, diethyl carbonate, ethylene carbonate, propylene carbonate, N, N-dimethylformamide, N, N- Methylacetamide, N-methylpyrrolidone, N-ethylpyrrolidone, acetic acid, ethyl acetate, acetonitrile, benzonitrile, benzene, o-, m-, p-xylene, toluene, o-, m-, p-TMB, chlorobenzene, o -, m-, p-dichlorobenzene, nitrobenzene, chloroform, methylene chloride and the like, but are not limited to the above solvents.

  The removal method of the residual solvent is not particularly limited in the method of performing the solvent removal step, but sublimation purification, recrystallization purification, column chromatography purification, reslurry, vacuum drying method, reprecipitation purification, liquid separation, water, solvent washing, filtration Filtering, ion exchange resin chromatography, activated carbon, diatomaceous earth, ion exchange resin, resin, adsorption with inorganic porous material (zeolite), air drying, heat drying method, freeze drying and the like.

  In addition, as a commercially available organic material for high-purity film formation, there are not many materials having a metal content of 10 ppm or less. Therefore, in the case where the organic material for film formation is commercially available, a commercially available organic material for film formation is prepared, and the step (A) includes a metal removal step so that the metal content is less than 10 ppm. It is preferable. It is preferable that the organic material 60 for film formation does not contain any metal such as Al, Fe, Cu, Zn, Zr, Ca, Mg, Cr, Ni, Mo, Mn, Na, Si, B, and K. It is preferable that halogen elements such as F, Cl, Br, and I are not included. In the step (A), it is more preferable to include a step of setting the halogen element content to less than 100 ppm. The metal removal step and the halogen element removal step may be performed in the purification step of step (B).

  When synthesizing a film-forming organic material, a metal removal step or a purification step may be performed using a high-purity film-forming organic material obtained by a normal synthesis method, or in the purification step during synthesis. You may implement the refinement | purification process in the said invention.

  After the refining step (B), halogen element removal step, and metal removal step are performed on the organic material for film formation, the film formation step (C) is performed using the organic material for film formation 60 by a predetermined dry film formation method. Then, the light receiving layer 30 (electron blocking layer 31 and photoelectric conversion layer 32) is formed.

  In the purification step (B) and the metal removal step, the formed organic material 60 is formed into a specific shape by pressurization, a sintered body obtained by firing and sintering, or a granule. In the case of a granulated sintered body obtained by firing it, the solvent removal step may be carried out after molding, granulating and sintering.

  In the film forming step (C) using the organic material 60 for film formation, the film forming speed is preferably 0.2 to 12 Å / s from the viewpoint of productivity. The film formation temperature may be any temperature within the range of the film formation rate (evaporation rate), and is preferably in the range of 350 to 750 ° C.

  In Examples described later, since the influence on the element characteristics of the photoelectric conversion element is large, the relative sensitivity and the organic material 60 for film formation are used in the photoelectric conversion layer 32 and the electron blocking layer 31 constituting the light receiving layer 30. Although the result of evaluating the number of CMOS defective pixels is shown, it can be preferably applied to a hole blocking layer (not shown).

  The film-forming organic material 60 is mainly composed of the constituent organic matter of the light-receiving layer 30 of the organic photoelectric conversion element 1 used in the optical sensor, and is a film-forming organic material that is highly purified by HPLC evaluation. And the content of the substance produced by the reaction of the constituent organic substance and / or metal, the intermediate produced in the production process of the constituent organic substance, and the substance produced by the reaction of this intermediate Less than 0.0% by mass. By using such an organic material for film formation, it is possible to stably form the light-receiving layer 30 with less mixing of substances that may cause pixel defects, and to stably manufacture the organic photoelectric conversion element 1 with few pixel defects. be able to.

  Below, the structure of the photoelectric conversion element 1 shown by FIG. 1 is demonstrated. As described above, in the configuration described below, the light receiving layer 30 such as the photoelectric conversion layer 32 and the electron blocking layer 31 which are organic layers is formed by the dry film formation method using the organic material 60 for film formation described above. Thereby, the photoelectric conversion element 1 with few pixel defects can be manufactured stably.

<Substrate and electrode>
There is no restriction | limiting in particular as the board | substrate 10, A silicon substrate, a glass substrate, etc. can be used.

  The lower electrode 20 is an electrode for collecting holes out of charges generated in the photoelectric conversion layer 32. The lower electrode 20 is not particularly limited as long as it has good conductivity. However, depending on the application, there are cases where transparency is provided, and conversely, a case where a material that does not have transparency and reflects light is used. is there. 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 upper electrode 40 is an electrode that collects electrons among the charges generated in the photoelectric conversion layer 32. The upper electrode 40 is not particularly limited as long as it is a conductive material that is sufficiently transparent to light having a wavelength with which the photoelectric conversion layer 32 has sensitivity in order to allow light to enter the photoelectric conversion layer 32. 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 and nickel, and mixtures or laminates of these metals and conductive metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, organic materials such as polyaniline, polythiophene and polypyrrole Examples thereof include conductive materials and laminates of these with ITO. Among these, conductive metal oxides are preferable from the viewpoint of high conductivity and transparency.

  The method for forming the electrode is not particularly limited, and can be appropriately selected in consideration of suitability with 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.

  Since the upper electrode 40 is formed on the organic photoelectric conversion layer 32, it is preferable that the upper electrode 40 be formed by a method that does not deteriorate the characteristics of the organic photoelectric conversion layer 32. Therefore, it is preferable that the upper electrode 40 be formed free of plasma. Here, plasma free means that no plasma is generated during the deposition of the upper electrode 40, or that 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. It means a state in which the plasma that reaches is reduced.

  Examples of apparatuses that do not generate plasma during the formation of the upper electrode 40 include an electron beam vapor deposition apparatus (EB vapor deposition apparatus) and a pulse laser vapor deposition apparatus. Regarding EB deposition equipment or pulse laser deposition equipment, “Surveillance of Transparent Conductive Films” supervised by Yutaka Sawada (published by CMC, 1999), “New Development of Transparent Conductive Films II” supervised by Yutaka Sawada (published by CMC, 2002) ), "Transparent conductive film technology" by the Japan Society for the Promotion of Science (Ohm Co., 1999), and the references attached thereto, etc. can be used. 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.

  For an apparatus that can realize a state in which the distance from the plasma generation source to the substrate is 2 cm or more and the arrival of plasma to the substrate is reduced (hereinafter referred to as a plasma-free film forming apparatus), for example, an opposed target sputtering Equipment, arc plasma deposition, etc. are considered, and these are supervised by Yutaka Sawada "New development of transparent conductive film" (published by CMC, 1999), and supervised by Yutaka Sawada "New development of transparent conductive film II" (published by CMC) 2002), “Transparent conductive film technology” (Ohm Co., 1999) by the Japan Society for the Promotion of Science, and references and the like attached thereto can be used.

  When a transparent conductive film such as TCO is used as the upper electrode 40, a DC short circuit or an increase in leakage current may occur. One reason for this is thought to be that fine cracks introduced into the photoelectric conversion layer 32 are covered with a dense film such as TCO, and conduction between the lower electrode 20 on the opposite side is increased. For this reason, in the case of an electrode having a poor film quality such as Al, an increase in leakage current hardly occurs. By controlling the film thickness of the upper electrode 40 with respect to the film thickness of the photoelectric conversion layer 32 (that is, the depth of cracks), an increase in leakage current can be largely suppressed. It is desirable that the thickness of the upper electrode 40 is 1/5 or less, preferably 1/10 or less of the thickness of the photoelectric conversion layer 32.

  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, the thinner the upper electrode 40 is, the less light is absorbed, and the light transmittance is generally increased. The increase in light transmittance is very preferable because it increases the light absorption in the photoelectric conversion layer 32 and increases the photoelectric conversion ability. In consideration of 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 40 is preferably 5 to 100 nm, and more preferably 5 to 20 nm. preferable.

  By applying a bias voltage between the upper electrode 40 and the lower electrode 20, among the charges generated in the photoelectric conversion layer 32, holes can be moved to the lower electrode 20 and electrons can be moved to the upper electrode 40.

<Light receiving layer>
The light receiving layer 30 is an organic layer including at least the photoelectric conversion layer 32, and includes an organic layer formed by a dry film forming method using the film forming organic material 60. In the present embodiment, the light receiving layer 30 includes an electron blocking layer 31 and a photoelectric conversion layer 32, and either or both of these are formed by a dry film forming method using the film forming organic material 60. ing. In order to further suppress the incorporation of pixel defects and variations thereof, it is preferable that as many layers as possible of the organic layers included in the light receiving layer 30 are formed using the organic material 60 for film formation.

  The light receiving layer 30 can be formed by a dry film forming method or a wet film forming method. The dry film formation method is preferable in that a uniform film formation is easy and impurities are not easily mixed, and that film thickness control and lamination on different materials are easy.

  Specific examples of the dry film forming method include a vacuum vapor deposition method, a sputtering method, an ion plating method, a physical vapor deposition method such as an MBE method, or a CVD method such as plasma polymerization. A vacuum deposition method is preferred, and in the case of forming a film by the vacuum deposition method, the production conditions such as the degree of vacuum and the deposition temperature can be set according to conventional methods. When the light receiving layer 30 is formed by the vapor deposition method, it is preferable that the decomposition temperature is higher than the vapor deposition possible temperature because thermal decomposition during vapor deposition can be suppressed.

When the light receiving layer 30 is formed by a dry film forming method, the degree of vacuum at the time of formation is preferably 1 × 10 ⁻³ Pa or less in consideration of preventing deterioration of element characteristics at the time of forming the light receiving layer. ⁻⁴ Pa or less is more preferable, and 1 × 10 ⁻⁴ Pa or less is particularly preferable.

  The thickness of the light receiving layer 30 is preferably 10 nm to 1000 nm, more preferably 50 nm to 800 nm, and particularly preferably 100 nm to 600 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.

<< Photoelectric conversion layer >>
The photoelectric conversion layer 32 receives light and generates an electric charge according to the amount of light, and includes an organic photoelectric conversion material.

  The photoelectric conversion element 1 of the present embodiment has a configuration in which a photoelectric conversion layer 32 includes a mixed layer (bulk hetero layer) in which a p-type organic semiconductor (p-type organic compound) and an n-type organic semiconductor are mixed. . This mixed layer is preferably formed by co-evaporation of the organic material 60 for forming a p-type organic semiconductor material and the organic material 60 for forming an n-type organic semiconductor material.

  Here, the mixed layer refers to a layer in which a plurality of materials are mixed or dispersed. In this embodiment, the mixed layer is a layer formed by co-evaporating a p-type organic semiconductor and an n-type organic semiconductor. .

  Although it does not restrict | limit especially as an n-type organic semiconductor (compound) which comprises the photoelectric converting layer 32, It is preferable that it is a fullerene or a fullerene derivative. Examples of fullerenes include fullerene C60, fullerene C70, fullerene C76, fullerene C78, fullerene C80, fullerene C82, fullerene C84, fullerene C90, fullerene C96, fullerene C240, fullerene 540, mixed fullerene, and fullerene nanotubes.

  The fullerene derivative means a compound having a substituent added thereto. The substituent for the fullerene derivative is preferably an alkyl group, an aryl group, or a heterocyclic group. More preferably, the alkyl group is an alkyl group having 1 to 12 carbon atoms, and the aryl group and the heterocyclic group are preferably a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, fluorene ring, triphenylene ring, naphthacene ring. , Biphenyl ring, pyrrole ring, furan ring, thiophene ring, imidazole ring, oxazole ring, thiazole ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, indolizine ring, indole ring, benzofuran ring, benzothiophene ring, isobenzofuran Ring, benzimidazole ring, imidazopyridine ring, quinolidine ring, quinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinoxazoline ring, isoquinoline ring, carbazole ring, phenanthridine ring, acridine ring, phenanthroline , Thianthrene ring, chromene ring, xanthene ring, phenoxathiin ring, phenothiazine ring, or phenazine ring, more preferably a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, pyridine ring, imidazole ring, oxazole ring, or A thiazole ring, particularly preferably a benzene ring, a naphthalene ring, or a pyridine ring. These may further have a substituent, and the substituents may be bonded as much as possible to form a ring. In addition, you may have a some substituent and they may be the same or different. A plurality of substituents may be combined as much as possible to form a ring.

  The p-type organic semiconductor (compound) constituting the photoelectric conversion layer 32 preferably has an appropriate particle size that does not greatly affect the stability of the deposition rate. The average particle diameter of the p-type organic semiconductor and the n-type organic semiconductor is preferably 10 to 800 μm, and more preferably 20 to 700 μm.

  The p-type organic semiconductor (compound) constituting the photoelectric conversion layer 32 is a donor 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, triarylamine compounds, pyran compounds, quinacridone compounds, benzidine compounds, pyrazoline compounds, styrylamine compounds, hydrazone compounds, triphenylmethane compounds, carbazole compounds, polysilane compounds, thiophene compounds, phthalocyanine compounds, cyanine compounds, merocyanine compounds, oxonol Compound, polyamine compound, indole compound, pyrrole compound, pyrazole compound, polyarylene compound, condensed aromatic carbocyclic compound (naphthalene derivative, anthracene derivative, phenanthrene derivative, tetracene derivative, pyrene derivative, perylene derivative, fluoranthene derivative), nitrogen-containing hetero A metal complex having a ring compound as a ligand can be used. However, the present invention is not limited thereto, and any organic compound having an ionization potential smaller than that of the organic compound used as the n-type organic semiconductor may be used as the donor organic semiconductor.

Among the above, preferred are triarylamine compounds, pyran compounds, quinacridone compounds, pyrrole compounds, phthalocyanine compounds, merocyanine compounds, and condensed aromatic carbocyclic compounds.

Any organic dye may be used as the p-type organic semiconductor, but preferred are a cyanine dye, a styryl dye, a hemicyanine dye, a merocyanine dye (including zero methine merocyanine (simple merocyanine)), a trinuclear merocyanine dye, 4 Nuclear merocyanine dye, rhodacyanine dye, complex cyanine dye, complex merocyanine dye, allopolar dye, oxonol dye, hemioxonol dye, squalium dye, croconium dye, azamethine dye, coumarin dye, arylidene dye, anthraquinone dye, triphenylmethane dye, azo Dye, azomethine dye, spiro compound, metallocene dye, fluorenone dye, fulgide dye, perylene dye, perinone dye, phenazine dye, phenothiazine dye, quinone color , Diphenylmethane dye, polyene dye, acridine dye, acridinone dye, diphenylamine dye, quinacridone dye, quinophthalone dye, phenoxazine dye, phthaloperylene dye, diketopyrrolopyrrole dye, dioxane dye, porphyrin dye, chlorophyll dye, phthalocyanine dye, metal complex dye And condensed aromatic carbocyclic dyes (naphthalene derivatives, anthracene derivatives, phenanthrene derivatives, tetracene derivatives, pyrene derivatives, perylene derivatives, fluoranthene derivatives). Specific p-type organic semiconductors (compounds) are exemplified below, but are not limited to the compounds listed below.
The fullerene constituting the photoelectric conversion layer 32 is not particularly limited, and fullerene C60, fullerene C70, fullerene C76, fullerene C78, fullerene C80, fullerene C82, fullerene C84, fullerene C90, fullerene C96, fullerene C240, fullerene 540, mixed fullerene. And fullerene nanotubes. A typical fullerene skeleton is shown below.
The fullerene derivative means a compound having a substituent added thereto. The substituent for the fullerene derivative is preferably an alkyl group, an aryl group, or a heterocyclic group. More preferably, the alkyl group is an alkyl group having 1 to 12 carbon atoms, and the aryl group and the heterocyclic group are preferably a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, fluorene ring, triphenylene ring, naphthacene ring. , Biphenyl ring, pyrrole ring, furan ring, thiophene ring, imidazole ring, oxazole ring, thiazole ring, pyridine ring, pyrazine ring, pyrimidine ring, pyridazine ring, indolizine ring, indole ring, benzofuran ring, benzothiophene ring, isobenzofuran Ring, benzimidazole ring, imidazopyridine ring, quinolidine ring, quinoline ring, phthalazine ring, naphthyridine ring, quinoxaline ring, quinoxazoline ring, isoquinoline ring, carbazole ring, phenanthridine ring, acridine ring, phenanthroline , Thianthrene ring, chromene ring, xanthene ring, phenoxathiin ring, phenothiazine ring, or phenazine ring, more preferably a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, pyridine ring, imidazole ring, oxazole ring, or A thiazole ring, particularly preferably a benzene ring, a naphthalene ring, or a pyridine ring. These may further have a substituent, and the substituents may be bonded as much as possible to form a ring. In addition, you may have a some substituent and they may be the same or different. A plurality of substituents may be combined as much as possible to form a ring.

  When the photoelectric conversion layer 32 contains fullerene or a fullerene derivative, the charge generated by the photoelectric conversion can be quickly transported to the lower electrode 20 or the upper electrode 40 via the fullerene molecule or the fullerene derivative molecule. When fullerene molecules or fullerene derivative molecules are connected to form an electron path, the electron transport property is improved, and the high-speed response of the organic photoelectric conversion element can be realized. For this purpose, the fullerene or fullerene derivative is preferably contained in the photoelectric conversion layer 32 by 40% or more. However, when there are too many fullerenes or fullerene derivatives, the p-type organic semiconductor is reduced, the junction interface is reduced, and the exciton dissociation efficiency is lowered.

  When the triarylamine compound described in Japanese Patent No. 4213832 is used as a p-type organic semiconductor mixed with fullerene or a fullerene derivative in the photoelectric conversion layer 32, a high SN ratio of the organic photoelectric conversion element can be expressed. Is particularly preferred. If the ratio of fullerene or fullerene derivative in the photoelectric conversion layer 32 is too large, the amount of the triarylamine compound is reduced and the amount of incident light absorbed is reduced. As a result, the photoelectric conversion efficiency is reduced, so that the fullerene or fullerene derivative contained in the photoelectric conversion layer 32 preferably has a composition of 85% or less.

  Further, as described above, in the photoelectric conversion layer 32, the mixed layer obtained by mixing the p-type organic semiconductor and the fullerene or the fullerene derivative is represented by D50% of the plurality of particles mainly composed of the fullerene or the fullerene derivative. It is assumed that vapor deposition is performed using a vapor deposition material for photoelectric conversion elements having an average particle diameter of 50 μm to 300 μm. A film containing fullerene or a fullerene derivative deposited using such a vapor deposition material is formed using a vapor deposition material in which the particle size of particles containing fullerene or a fullerene derivative is optimized. Therefore, as will be described later in Examples, the photoelectric conversion element 1 provided with such a photoelectric conversion layer 32 has high photoelectric conversion efficiency, good S / N ratio of photocurrent / dark current, and response speed. It will be fast.

In order to express the effect of the present invention remarkably, the p-type organic semiconductor is preferably a compound represented by the following general formula (1).
(In the formula, L2 and L3 each independently represent an unsubstituted methine group or a substituted methine group. N represents an integer of 0 to 2. Ar1 represents a divalent substituted arylene group or an unsubstituted arylene group. Ar2 and Ar3 each independently represent a substituted aryl group, an unsubstituted aryl group, a substituted alkyl group, an unsubstituted alkyl group, a substituted heteroaryl group, or an unsubstituted heteroaryl group, and adjacent to Ar1, Ar2, and Ar3 L1 may be bonded to each other to form a ring, and L1 represents an unsubstituted methine group or a substituted methine group bonded to the following general formula (2), or a group represented by the following general formula (3). Represent.
In the formula, Z1 is a ring containing a carbon atom bonded to L1 and a carbonyl group adjacent to the carbon atom, and is a 5-membered ring, a 6-membered ring, or at least one of a 5-membered ring and a 6-membered ring. Represents a condensed ring containing X represents a hetero atom. Z2 is a ring containing X and represents a 5-membered ring, a 6-membered ring, a 7-membered ring, or a condensed ring containing at least one of a 5-membered ring, a 6-membered ring and a 7-membered ring. L4 to L6 each independently represents an unsubstituted methine group or a substituted methine group. R6 and R7 each independently represents a hydrogen atom or a substituent, and adjacent ones may be bonded to each other to form a ring. k represents an integer of 0-2. * In the general formula (2) represents a bonding position bonded to L1, and * in the general formula (3) represents a bonding position bonded to L2 or Ar1.

Z1 in the general formula (2) is a ring containing two carbon atoms and represents a 5-membered ring, a 6-membered ring, or a condensed ring containing at least one of a 5-membered ring and a 6-membered ring. As such a ring, what is normally used as an acidic nucleus with a merocyanine dye is preferable, and specific examples thereof include the following.
(A) 1,3-dicarbonyl nucleus: For example, 1,3-indandione nucleus, 1,3-cyclohexanedione, 5,5-dimethyl-1,3-cyclohexanedione, 1,3-dioxane-4,6- Zeon etc.
(B) pyrazolinone nucleus: for example 1-phenyl-2-pyrazolin-5-one, 3-methyl-1-phenyl-2-pyrazolin-5-one, 1- (2-benzothiazoyl) -3-methyl-2 -Pyrazolin-5-one and the like.
(C) Isoxazolinone nucleus: For example, 3-phenyl-2-isoxazolin-5-one, 3-methyl-2-isoxazolin-5-one and the like.
(D) Oxindole nucleus: For example, 1-alkyl-2,3-dihydro-2-oxindole and the like.
(E) 2,4,6-triketohexahydropyrimidine nucleus: for example, barbituric acid or 2-thiobarbituric acid and its derivatives. Examples of the derivatives include 1-alkyl compounds such as 1-methyl and 1-ethyl, 1,3-dialkyl compounds such as 1,3-dimethyl, 1,3-diethyl and 1,3-dibutyl, 1,3-diphenyl, 1,3-diaryl compounds such as 1,3-di (p-chlorophenyl) and 1,3-di (p-ethoxycarbonylphenyl), 1-alkyl-1-aryl compounds such as 1-ethyl-3-phenyl, Examples include 1,3-di (2-pyridyl) 1,3-diheterocyclic substituents and the like.
(F) 2-thio-2,4-thiazolidinedione nucleus: for example, rhodanine and derivatives thereof. Examples of the derivatives include 3-alkylrhodanine such as 3-methylrhodanine, 3-ethylrhodanine and 3-allylrhodanine, 3-arylrhodanine such as 3-phenylrhodanine, and 3- (2-pyridyl) rhodanine. And the like.
(G) 2-thio-2,4-oxazolidinedione (2-thio-2,4- (3H, 5H) -oxazoledione nucleus: for example, 3-ethyl-2-thio-2,4-oxazolidinedione and the like.
(H) Tianaphthenone nucleus: For example, 3 (2H) -thianaphthenone-1,1-dioxide and the like.
(I) 2-thio-2,5-thiazolidinedione nucleus: for example, 3-ethyl-2-thio-2,5-thiazolidinedione and the like.
(J) 2,4-thiazolidinedione nucleus: For example, 2,4-thiazolidinedione, 3-ethyl-2,4-thiazolidinedione, 3-phenyl-2,4-thiazolidinedione, and the like.
(K) Thiazolin-4-one nucleus: For example, 4-thiazolinone, 2-ethyl-4-thiazolinone and the like.
(L) 2,4-imidazolidinedione (hydantoin) nucleus: for example, 2,4-imidazolidinedione, 3-ethyl-2,4-imidazolidinedione, etc.
(M) 2-thio-2,4-imidazolidinedione (2-thiohydantoin) nucleus: for example, 2-thio-2,4-imidazolidinedione, 3-ethyl-2-thio-2,4-imidazolidinedione etc.
(N) 2-imidazolin-5-one nucleus: For example, 2-propylmercapto-2-imidazolin-5-one and the like.
(O) 3,5-pyrazolidinedione nucleus: for example, 1,2-diphenyl-3,5-pyrazolidinedione, 1,2-dimethyl-3,5-pyrazolidinedione and the like.
(P) Benzothiophen-3-one nucleus: for example, benzothiophen-3-one, oxobenzothiophen-3-one, dioxobenzothiophen-3-one and the like.
(Q) Indanone nucleus: For example, 1-indanone, 3-phenyl-1-indanone, 3-methyl-1-indanone, 3,3-diphenyl-1-indanone, 3,3-dimethyl-1-indanone and the like.

  The ring represented by Z1 is preferably a 1,3-dicarbonyl nucleus, a pyrazolinone nucleus, a 2,4,6-triketohexahydropyrimidine nucleus (including a thioketone body, for example, a barbituric acid nucleus, a 2-thiobarbituric acid nucleus). 2-thio-2,4-thiazolidinedione nucleus, 2-thio-2,4-oxazolidinedione nucleus, 2-thio-2,5-thiazolidinedione nucleus, 2,4-thiazolidinedione nucleus, 2,4-imidazo Lysine dione nucleus, 2-thio-2,4-imidazolidinedione nucleus, 2-imidazoline-5-one nucleus, 3,5-pyrazolidinedione nucleus, benzothiophen-3-one nucleus, indanone nucleus, and more Preferably, 1,3-dicarbonyl nucleus, 2,4,6-triketohexahydropyrimidine nucleus (including thioketone body, for example, barbituric acid nucleus, 2-thiobarbitu Acid nucleus), 3,5-pyrazolidinedione nucleus, benzothiophen-3-one nucleus, indanone nucleus, more preferably 1,3-dicarbonyl nucleus, 2,4,6-triketohexahydropyrimidine nucleus (Including thioketone bodies, for example, barbituric acid nucleus, 2-thiobarbituric acid nucleus), particularly preferably 1,3-indandione nucleus, barbituric acid nucleus, 2-thiobarbituric acid nucleus and derivatives thereof. .

A preferable ring represented by Z1 is represented by the following formula.
In the formula, Z3 is a ring containing a carbon atom bonded to L1 and two carbonyl groups adjacent to the carbon atom, and is a 5-membered ring, a 6-membered ring, or a 5-membered ring and a 6-membered ring. Represents a condensed ring containing * Indicates a binding position for binding to L1. Z3 can be selected from the ring represented by Z1 above, preferably 1,3-dicarbonyl nucleus, 2,4,6-triketohexahydropyrimidine nucleus (including thioketone body), particularly preferably 1 , 3-indandione nucleus, barbituric acid nucleus, 2-thiobarbituric acid nucleus and derivatives thereof.

When the ring represented by Z1 is a 1,3-indandione nucleus, it is preferably a group represented by the following general formula (5).
In the formula, R2 to R5 each independently represent a hydrogen atom or a substituent, and adjacent ones may be bonded to each other to form a ring. * Indicates a binding position for binding to L1.

K in the general formula (3) represents an integer of 0 to 2, preferably 0 or 1, more preferably 0. X is preferably O, S, or N-R10. A preferable ring represented by Z2 is represented by the following formula (6).
In the formula, X represents O, S, or N-R10. R10 represents a hydrogen atom or a substituent. In the formula, R 1, R 6 and R 7 each independently represent a hydrogen atom or a substituent, and adjacent ones may be bonded to each other to form a ring. m represents an integer of 1 to 3. When m is 2 or more, the plurality of R1s may be the same or different. * Represents a bonding position for bonding to L2 or Ar1.

  The arylene group represented by Ar1 is preferably an arylene group having 6 to 30 carbon atoms, and more preferably an arylene group having 6 to 18 carbon atoms. The arylene group may have a substituent, and is preferably an arylene group having 6 to 18 carbon atoms which may have an alkyl group having 1 to 4 carbon atoms. Examples include a phenylene group, a naphthylene group, a methylphenylene group, a dimethylphenylene group, and the like, and a phenylene group and a naphthylene group are preferable.

  The aryl groups represented by Ar2 and Ar3 are each independently preferably an aryl group having 6 to 30 carbon atoms, and more preferably an aryl group having 6 to 18 carbon atoms. The aryl group may have a substituent, preferably an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 18 carbon atoms which may have an aryl group having 6 to 18 carbon atoms. is there. For example, a phenyl group, a naphthyl group, a tolyl group, an anthryl group, a dimethylphenyl group, a biphenyl group etc. are mentioned, A phenyl group and a naphthyl group are preferable.

  The alkyl group represented by Ar2 and Ar3 is preferably an alkyl group having 1 to 6 carbon atoms, and more preferably an alkyl group having 1 to 4 carbon atoms. Examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a t-butyl group. A methyl group or an ethyl group is preferable, and a methyl group is more preferable.

  The heteroaryl groups represented by Ar2 and Ar3 are preferably each independently a heteroaryl group having 3 to 30 carbon atoms, and more preferably a heteroaryl group having 3 to 18 carbon atoms. The heteroaryl group may have a substituent, and preferably a heteroaryl having 3 to 18 carbon atoms which may have an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 18 carbon atoms. It is a group. The heteroaryl group represented by Ar2 and Ar3 may have a condensed ring structure, such as a furan ring, a thiophene ring, a selenophene ring, a silole ring, a pyridine ring, a pyrazine ring, a pyrimidine ring, an oxazole ring, a thiazole ring, a triazole ring, A condensed ring structure of a combination of rings selected from an oxadiazole ring and a thiadiazole ring (which may be the same) is preferable. A quinoline ring, an isoquinoline ring, a benzothiophene ring, a dibenzothiophene ring, a thienothiophene ring, a bithienobenzene ring, A thienothiophene ring is preferred.

  Ar 1, Ar 2, Ar 3, R 1, R 2 to R 7, R 10 may be adjacent to each other to form a ring. Furthermore, the ring is preferably a ring formed of a hetero atom, an alkylene group, an aromatic ring, or the like. For example, two aryl groups (for example, Ar1, Ar2, and Ar3 in the general formula (1)) are connected together through a single bond or a linking group to form a nitrogen atom (N in the general formula (1)). A ring is mentioned. Examples of the linking group include heteroatoms (for example, —O—, —S—, etc.), alkylene groups (for example, methylene group, ethylene group, etc.), and groups comprising a combination thereof, —S—, A methylene group is preferred. A ring formed by a nitrogen atom (for example, N in the general formula (1)), an alkylene group (for example, a methylene group) and an aryl group (for example, Ar1, Ar2 or Ar3 in the general formula (1)) is preferable. The ring may further have a substituent, and examples of the substituent include an alkyl group (preferably an alkyl group having 1 to 4 carbon atoms, more preferably a methyl group). They may be connected to each other to further form a ring (for example, a benzene ring).

  R3 and R4 are preferably connected to each other to form a ring, and the ring is preferably a benzene ring.

  Furthermore, when there are a plurality of R1s (m is 2 or more), adjacent ones of the plurality of R1s can be connected to each other to form a ring, and the ring is preferably a benzene ring.

In the case where Ar1, Ar2, Ar3 has a substituent, and the substituents of R1, R2-R7, and R10 include a halogen atom, an alkyl group (including a cycloalkyl group, a bicycloalkyl group, and a tricycloalkyl group) ), Substituted alkyl groups, alkenyl groups (including cycloalkenyl groups and bicycloalkenyl groups), alkynyl groups, aryl groups, substituted aryl groups, heterocyclic groups (also referred to as heterocyclic groups), cyano groups, hydroxy groups, Nitro group, carboxy group, alkoxy group, aryloxy group, silyloxy group, heterocyclic oxy group, acyloxy group, carbamoyloxy group, alkoxycarbonyl group, aryloxycarbonyl group, amino group (including anilino group), ammonio group, acylamino Group, aminocarbonylamino group, alkoxycarbonyl Mino group, aryloxycarbonylamino group, sulfamoylamino group, alkyl and arylsulfonylamino group, mercapto group, alkylthio group, arylthio group, heterocyclic thio group, sulfamoyl group, sulfo group, alkyl and arylsulfinyl group, alkyl and Arylsulfonyl group, acyl group, aryloxycarbonyl group, alkoxycarbonyl group, carbamoyl group, aryl and heterocyclic azo group, imide group, phosphino group, phosphinyl group, phosphinyloxy group, phosphinylamino group, phosphono group, Examples include silyl groups, hydrazino groups, ureido groups, boronic acid groups (—B (OH) ₂ ), phosphato groups (—OPO (OH) ₂ ), sulfato groups (—OSO ₃ H), and other known substituents. . As substituents for R1, R2 to R7, R10, alkyl groups, substituted alkyl groups, aryl groups, substituted aryl groups, heteroaryl groups, cyano groups, nitro groups, alkoxy groups, aryloxy groups, amino groups, alkylthio groups, in particular , An alkenyl group or a halogen atom is preferred.

When Ar1, Ar2, Ar3 has a substituent, each independently a halogen atom, alkyl group, aryl group, heterocyclic group, hydroxy group, nitro group, alkoxy group, aryloxy group, heterocyclic oxy group, amino group, alkylthio Group, arylthio group, alkenyl group, cyano group or heterocyclic thio group is preferred.
R1 is more preferably an alkyl group or an aryl group. R6 and R7 are more preferably a cyano group.

  Examples of the substituent of the substituted alkyl group or the substituted aryl group include the substituents listed above. An alkyl group (preferably an alkyl group having 1 to 4 carbon atoms, more preferably a methyl group) or an aryl group (carbon). An aryl group of formula 6-18, more preferably a phenyl group, is preferred.

  When L1, L2, L3, L4, L5, and L6 each independently represent an unsubstituted methine group or a substituted methine group, the substituent of the substituted methine group is an alkyl group, an aryl group, a heterocyclic group, an alkenyl group, an alkoxy group Represents a group or an aryloxy group, and substituents may be bonded to each other to form a ring. A 6-membered ring (for example, benzene ring etc.) is mentioned as a ring. Further, the substituents of L1 or L3 and Ar1 may be bonded to form a ring. Moreover, the substituents of L6 and R7 may be bonded to form a ring.

  As an alkyl group which R1, R2-R7, R10 represents, Preferably it is a C1-C6 alkyl group, More preferably, it is a C1-C4 alkyl group. Examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, and a t-butyl group. As R2 to R7, a methyl group or an ethyl group is preferable, and a methyl group is more preferable. As R1, a methyl group, an ethyl group or a t-butyl group is preferable, and a methyl group or a t-butyl group is more preferable. n is preferably 0 or 1.

  The aryl groups represented by R1, R2 to R7, and R10 are each independently preferably an aryl group having 6 to 30 carbon atoms, and more preferably an aryl group having 6 to 18 carbon atoms. The aryl group may have a substituent, preferably an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 18 carbon atoms which may have an aryl group having 6 to 18 carbon atoms. is there. Examples include a phenyl group, a naphthyl group, an anthracenyl group, a pyrenyl group, a phenanthrenyl group, a methylphenyl group, a dimethylphenyl group, a biphenyl group, and the like, and a phenyl group, a naphthyl group, or an anthracenyl group is preferable.

  The heteroaryl groups represented by R1, R2 to R7, and R10 are each independently preferably a heteroaryl group having 3 to 30 carbon atoms, and more preferably a heteroaryl group having 3 to 18 carbon atoms. The heteroaryl group may have a substituent, and preferably a heteroaryl having 3 to 18 carbon atoms which may have an alkyl group having 1 to 4 carbon atoms or an aryl group having 6 to 18 carbon atoms. It is a group. The heteroaryl group represented by R1, R2 to R7 is preferably a heteroaryl group comprising a 5-membered, 6-membered or 7-membered ring or a condensed ring thereof. Examples of the hetero atom contained in the heteroaryl group include an oxygen atom, a sulfur atom, and a nitrogen atom. Specific examples of the ring constituting the heteroaryl group include a furan ring, a thiophene ring, a pyrrole ring, a pyrroline ring, a pyrrolidine ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, an imidazoline ring, and an imidazolidine. Ring, pyrazole ring, pyrazoline ring, pyrazolidine ring, triazole ring, furazane ring, tetrazole ring, pyran ring, thiine ring, pyridine ring, piperidine ring, oxazine ring, morpholine ring, thiazine ring, pyridazine ring, pyrimidine ring, pyrazine ring, Examples include a piperazine ring and a triazine ring.

  As the condensed ring, benzofuran ring, isobenzofuran ring, benzothiophene ring, indole ring, indoline ring, isoindole ring, benzoxazole ring, benzothiazole ring, indazole ring, benzimidazole ring, quinoline ring, isoquinoline ring, cinnoline ring, Phthalazine ring, quinazoline ring, quinoxaline ring, dibenzofuran ring, carbazole ring, xanthene ring, acridine ring, phenanthridine ring, phenanthroline ring, phenazine ring, phenoxazine ring, thianthrene ring, thienothiophene ring, indolizine ring, quinolidine ring, A quinuclidine ring, a naphthyridine ring, a purine ring, a pteridine ring, etc. are mentioned.

  m represents an integer of 1 to 3, preferably 1 or 2, and more preferably 1.

Among the compounds represented by the general formula (1), the following compounds are particularly preferable.
<< Electron blocking layer >>
The electron blocking layer 31 included in the light receiving layer 30 suppresses the injection of electrons from the lower electrode 20 into the photoelectric conversion layer 32 and inhibits the electrons generated in the photoelectric conversion layer 32 from flowing to the electrode 2 side. Layer. The electron blocking layer 31 includes an organic material, an inorganic material, or both.

  The electron blocking layer 31 may be composed of a plurality of layers. By doing in this way, an interface is formed between each layer which comprises the electron blocking layer 31, and a discontinuity arises in the intermediate level which exists in each layer. As a result, it becomes difficult for the charge to move through the intermediate level and the like, so that the electron blocking effect can be enhanced. However, if the layers constituting the electron blocking layer 31 are made of the same material, the intermediate levels existing in the layers may be exactly the same. Therefore, in order to further enhance the electron blocking effect, the materials constituting the layers are different. It is preferable to make it.

An electron-donating organic material can be used for the electron blocking layer 31. Specifically, in a low molecular material, 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), porphine, tetraphenylporphine copper, phthalocyanine, copper phthalocyanine, titanium phthalocyanine oxide, etc. Porphyrin compounds , triazole derivatives, oxadiazo Derivatives , imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, fluorene derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, silazane derivatives, etc. As the polymer material, polymers such as phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, diacetylene, and derivatives thereof can be used. Even if it is not, it is possible to use a compound having sufficient hole transportability.

Specifically, for example, the following compounds described in JP-A-2008-72090 are shown, but the present invention is not limited thereto. The following Ea represents the electron affinity of the material, and Ip represents the ionization potential of the material. “EB” in EB-1, 2,... Stands for “electronic blocking”.
An inorganic material can also be used as the electron blocking layer 31. In general, since an inorganic material has a dielectric constant larger than that of an organic material, when it is used for the electron blocking layer 31, a large voltage is applied to the photoelectric conversion layer 32, and the photoelectric conversion efficiency can be increased. Materials that can be the electron blocking layer 31 include calcium oxide, chromium oxide, chromium oxide copper, manganese oxide, cobalt oxide, nickel oxide, copper oxide, gallium copper oxide, strontium copper oxide, niobium oxide, molybdenum oxide, indium copper oxide, Examples include indium silver oxide and iridium oxide.

  In the electron blocking layer 31 composed of a plurality of layers, the layer adjacent to the photoelectric conversion layer 32 among the plurality of layers is preferably a layer made of the same material as the p-type organic semiconductor contained in the photoelectric conversion layer 32. By using the same p-type organic semiconductor for the electron blocking layer 31, it is possible to suppress the formation of intermediate levels at the interface between the photoelectric conversion layer 32 and the adjacent layer, and to further suppress the dark current.

  When the electron blocking layer 31 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. it can.

  In addition, when a bias voltage is applied so as to collect electrons in the lower electrode 20 and collect holes in the upper electrode 40, a structure in which a hole blocking layer is provided instead of the electron blocking layer 31. And it is sufficient. The hole blocking layer suppresses injection of holes from the lower electrode 20 into the photoelectric conversion layer 32, and inhibits holes generated in the photoelectric conversion layer 32 from flowing toward the lower electrode 20 side. A layer formed of an organic material may be used. By making the hole blocking layer into a plurality of layers, the hole blocking effect can be enhanced.

  Further, electrons or holes collected by the upper electrode 40 may be converted into a voltage signal corresponding to the amount and taken out to the outside. In this case, an electron blocking layer or a hole blocking layer may be provided between the upper electrode 40 and the photoelectric conversion layer 32. In either case, the portion sandwiched between the lower electrode 20 and the upper electrode 40 becomes the light receiving layer 30.

An electron-accepting organic material can be used for the hole blocking layer. Examples of the electron-accepting material 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 complex,
Bis (4-methyl-8-quinolinato) aluminum complexes, distyrylarylene derivatives, silole compounds, and the like can be used. Even if it is not an electron-accepting organic material,
Any material having a sufficient electron transporting property can be used. A porphyrin-based compound or a styryl-based compound such as DCM (4-dicyanomethylene-2-methyl-6- (4- (dimethylaminostyryl))-4H pyran) or a 4H pyran-based compound can be used.

  The p-type organic semiconductor (compound) constituting the photoelectric conversion layer 32 is a donor 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.

  The hole blocking layer is also preferably formed using the organic material 60 for film formation.

<Sealing layer>
The sealing layer 50 is a layer for preventing a factor that degrades an organic material such as water and oxygen from entering the light receiving layer containing the organic material. The sealing layer 50 is formed so as to cover the lower electrode 20, the electron blocking layer 31, the photoelectric conversion layer 32, and the upper electrode 40.

  In the photoelectric conversion element 1, since incident light reaches the photoelectric conversion layer 32 through the sealing layer 50, the photoelectric conversion layer 32 has sufficient sensitivity to light having a wavelength with which the photoelectric conversion layer 32 has sensitivity. It must be transparent. Examples of the sealing layer 50 include ceramics such as dense metal oxide, metal nitride, and metal nitride oxide that do not allow water molecules to permeate, diamond-like carbon (DLC), and the like. Conventionally, aluminum oxide, silicon oxide, Silicon nitride, silicon nitride oxide, a laminated film thereof, a laminated film of them and an organic polymer, or the like is used.

  The sealing layer 50 can be composed of a thin film made of a single material, but by providing a separate function for each layer in a multi-layer structure, the stress relaxation of the entire sealing layer 50 and dust generation during the manufacturing process Such effects as the suppression of defects such as cracks and pinholes caused by the above, and the optimization of material development can be expected. For example, the sealing layer 50 is formed by laminating a “sealing auxiliary layer” having a function that is difficult to achieve on the layer that serves the original purpose of preventing the penetration of deterioration factors such as water molecules. A two-layer structure can be formed. Although it is possible to have three or more layers, it is preferable that the number of layers is as small as possible in consideration of manufacturing costs.

The formation method of the sealing layer 50 is not particularly limited, and is preferably formed by a method that does not deteriorate the performance and film quality of the already formed photoelectric conversion layer 32 and the like as much as possible. Conventionally, the film is generally formed by various vacuum film formation techniques, but the conventional sealing layer is a thin film at a step due to a structure on the substrate surface, minute defects on the substrate surface, particles adhering to the substrate surface, and the like. Is difficult to grow (because the step becomes a shadow), the film thickness is significantly thinner than the flat part. For this reason, the step portion becomes a path through which the deterioration factor penetrates. In order to completely cover the step with the sealing layer, it is necessary to form the film so as to have a film thickness of 1 μm or more in the flat portion, and to increase the thickness of the entire sealing layer. The degree of vacuum when forming the sealing layer is preferably 1 × 10 ³ Pa or less, and more preferably 5 × 10 ² Pa or less.

  However, in the case of an imaging device having a pixel size of less than 2 μm, particularly about 1 μm, if the sealing layer 50 is thick, the distance between the color filter and the photoelectric conversion layer increases, and incident light is transmitted within the sealing layer. Diffraction / divergence may occur and color mixing may occur. Therefore, when considering application to an image sensor having a pixel size of about 1 μm, a sealing layer material / manufacturing method is required that does not deteriorate the device performance even if the thickness of the sealing layer 50 is reduced.

  The atomic layer deposition (ALD) method is a kind of CVD method, and adsorption / reaction of organometallic compound molecules, metal halide molecules, and metal hydride molecules, which are thin film materials, onto the substrate surface and unreacted groups contained therein. Is a technique for forming a thin film by alternately repeating decomposition. When the thin film material reaches the substrate surface, it is in the above-mentioned low molecular state, so that the thin film can be grown in a very small space where the low molecule can enter. For this reason, the step portion, which was difficult with the conventional thin film formation method, is completely covered (the thickness of the thin film grown on the step portion is the same as the thickness of the thin film grown on the flat portion), that is, the step coverage is very high Excellent. For this reason, steps due to structures on the substrate surface, minute defects on the substrate surface, particles adhering to the substrate surface, and the like can be completely covered, and such a step portion does not become an intrusion path for a deterioration factor of the photoelectric conversion material. When the sealing layer 50 is formed by the atomic layer deposition method, the required sealing layer thickness can be effectively reduced as compared with the prior art.

  In the case of forming the sealing layer 50 by the atomic layer deposition method, a material corresponding to the ceramics preferable for the sealing layer 50 described above can be appropriately selected. However, since the photoelectric conversion layer of the present invention uses an organic photoelectric conversion material, it is limited to a material capable of growing a thin film at a relatively low temperature so that the organic photoelectric conversion material does not deteriorate. According to the atomic layer deposition method using alkyl aluminum or aluminum halide as the material, a dense aluminum oxide thin film can be formed at less than 200 ° C. at which the organic photoelectric conversion material does not deteriorate. In particular, when trimethylaluminum is used, an aluminum oxide thin film can be formed even at about 100 ° C. Silicon oxide and titanium oxide are also preferable because a dense thin film can be formed at less than 200 ° C., similarly to aluminum oxide, by appropriately selecting materials.

  In addition, the thin film formed by the atomic layer deposition method can achieve a high-quality thin film formation at a low temperature that is unparalleled from the viewpoint of step coverage and denseness. However, the physical properties of the thin film material may be deteriorated by chemicals used in the photolithography process. For example, since an aluminum oxide thin film formed by atomic layer deposition is amorphous, the surface is eroded by an alkaline solution such as a developer or a stripping solution.

  In addition, thin films formed by CVD, such as atomic layer deposition, often have tensile stresses with very large internal stress, such as processes that repeat intermittent heating and cooling, such as semiconductor manufacturing processes, Due to storage / use in a high temperature / high humidity atmosphere for a period, deterioration of the thin film itself may occur.

  Therefore, when the sealing layer 50 formed by the atomic layer deposition method is used, it is preferable to form a sealing auxiliary layer that has excellent chemical resistance and can cancel the internal stress of the sealing layer 50.

  Examples of the auxiliary sealing layer include any of ceramics such as metal oxide, metal nitride, and metal nitride oxide that are excellent in chemical resistance formed by physical vapor deposition (PVD) such as sputtering. Or a layer containing one of them. Ceramics formed by a PVD method such as sputtering often has a large compressive stress, and can cancel the tensile stress of the sealing layer 50 formed by an atomic layer deposition method.

The sealing layer 50 formed by the atomic layer deposition method preferably includes any of aluminum oxide, silicon oxide, and titanium oxide. The sealing auxiliary layer includes aluminum oxide, silicon oxide, silicon nitride, and silicon nitride oxide. A sputtered film containing any one of the above is preferable. In this case, the thickness of the sealing layer 50 is preferably 0.05 μm or more and 0.5 μm or less.
As described above, the photoelectric conversion element 1 is configured.

"Image sensor"
Next, the configuration of the image sensor (photosensor) 100 including the photoelectric conversion element 1 will be described with reference to FIG. FIG. 3 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.

  The image pickup device 100 is a circuit board on which a plurality of organic photoelectric conversion elements 1 configured as shown in FIG. 1 and a readout circuit that reads out signals corresponding to charges generated in the photoelectric conversion layer of each organic photoelectric conversion element are formed. And a plurality of organic photoelectric conversion elements are arranged one-dimensionally or two-dimensionally on the same surface above the circuit board.

  The image sensor 100 includes a substrate 101, an insulating layer 102, a connection electrode 103, a pixel electrode 104, a connection portion 105, a connection portion 106, a light receiving layer 107, a counter electrode 108, a buffer layer 109, a sealing layer. A stop layer 110, a color filter (CF) 111, a partition wall 112, a light shielding layer 113, a protective layer 114, a counter electrode voltage supply unit 115, and a readout circuit 116 are provided.

  The pixel electrode 104 has the same function as the lower electrode 20 of the organic photoelectric conversion element 1 shown in FIG. The counter electrode 108 has the same function as the upper electrode 40 of the organic photoelectric conversion element 1 shown in FIG. The light receiving layer 107 has the same configuration as the light receiving layer 30 provided between the lower electrode 20 and the upper electrode 40 of the organic photoelectric conversion element 1 shown in FIG. The sealing layer 110 has the same function as the sealing layer 50 of the organic photoelectric conversion element 1 shown in FIG. The pixel electrode 104, a part of the counter electrode 108 facing the pixel electrode 104, the light receiving layer 107 sandwiched between the electrodes, and the buffer layer 109 and the part of the sealing layer 110 facing the pixel electrode 104 are subjected to organic photoelectric conversion. The element is configured.

  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 light receiving layer 107 is a layer common to all the organic 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 light receiving layer 107 and common to all organic photoelectric conversion elements. The counter electrode 108 is formed up to the connection electrode 103 disposed outside the light receiving layer 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 reading circuit 116 is configured by, for example, a CCD, a MOS circuit, or a TFT circuit, and is shielded from light 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 light receiving layer 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 light receiving layer 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 substrate 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 light receiving layer 107, the counter electrode 108, the buffer layer 109, and the sealing layer 110 are sequentially formed on the plurality of pixel electrodes 104. The formation method of the light receiving layer 107, the counter electrode 108, and the sealing layer 110 is as described in the description of the photoelectric conversion element 1. The buffer layer 109 is formed by, for example, a vacuum resistance heating vapor 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.

  In the above description, in the imaging element and the photoelectric conversion element suitable as the imaging element, the aspect including the light receiving layer formed using the organic material for film formation of the present invention has been described. However, the organic material for film formation of the present invention has been described. 60 can also be preferably used for forming a light emitting layer in an organic electroluminescent device and a photoelectric conversion device suitable as an organic electroluminescent device.

(Examples 1-4, Comparative Examples 1-2)
A glass substrate was prepared, and an amorphous ITO lower electrode (thickness: 30 nm) was formed on the substrate by sputtering, and then the above-mentioned EB-3 was formed by vacuum resistance heating vapor deposition (100 nm thickness) as an electron blocking layer. ).

Next, as shown in Table 1, fullerenes (C ₆₀ ) having different amounts of foreign matters that could become pixel defects, and the compound 1 were prepared as film-forming organic materials for photoelectric conversion layers. For fullerene (C ₆₀ ), Comparative Example 2 in Table 1 was used as a commercially available fullerene vapor deposition source, and the amount of foreign matter in each example was adjusted and used by the method shown below so that the amount of foreign matter shown in Table 1 was achieved. . All the film-forming materials used had an HPLC purity of 99.5% or more, and the amount of metal impurities was less than 10 ppm each. Compound 1 was synthesized as follows, and the amount of foreign matter was common to the previous examples.

The adjustment of commercially available fullerene (C ₆₀ ) was performed as follows. First, the fullerene used as Comparative Example 2 was put in toluene and completely dissolved to prepare a solution (dissolution was visually determined). Five types of membrane filters (0.1 μm, 0 having different pore sizes) were prepared. .. 2 μm, 0.45 μm, 1 μm, 5 μm). Next, each filtrate was heated with an evaporator while reducing the pressure to remove the solvent, and the remaining powder was used as an organic material for film formation in each example.

  The amount of foreign matter remaining in each example was such that 10 mg of the powder of each example was completely dissolved in 50 ml of toluene, the solution was suction filtered with a membrane filter having a pore size of 0.1 μm, and then no foreign matter adhered. It measured by measuring the mass of the foreign material which remained on the filter after air-drying.

Compound 1 is disclosed in J. Org. Med. Chem. , 1973, Vol. 16, 1334-1339, Benz [f] indane-1,3-dione was synthesized, and 2 g of this sample and 3.1 g of 4- (N, N-diphenylamino) benzaldehyde were added in 20 ml of ethanol. The mixture was stirred for 6 hours under reflux and cooled to room temperature. The obtained crystals were separated by filtration, washed, and recrystallized from chloroform-acetonitrile.
Using the organic material for film formation in each example, a photoelectric conversion layer was formed on the electron blocking layer by co-evaporation so as to have a film thickness of 500 nm (Examples 1 to 4 and Comparative Examples 1 to 2). Co-evaporation was performed by vacuum resistance heating deposition. The vacuum deposition of the electron blocking layer and the photoelectric conversion layer was all performed at a vacuum degree of 4 × 10 ⁻⁴ Pa or less. The volume ratio of the fullerene C ₆₀ in the photoelectric conversion layer which is formed with the Compound 1 was 3: 1 (thickness conversion).

Next, an amorphous ITO upper electrode (10 nm thick) was formed on the photoelectric conversion layer by a sputtering method to obtain the photoelectric conversion element of the present invention. On the upper electrode, a SiO film was formed as a sealing layer by heating vapor deposition, and an Al ₂ O ₃ layer was further formed by ALCVD.

  In addition, the image pickup device of each example was manufactured in the same manner as described above except that a CMOS substrate on which a readout circuit composed of a CMOS circuit and a connection electrode connected thereto was used as the substrate.

[Evaluation]
The relative sensitivity to light having a wavelength of 500 to 750 nm when applied with an electric field of 2 × 10 ⁵ V / cm was measured for the obtained photoelectric conversion elements. In the measurement of the photoelectric conversion performance of each element, light was incident from the upper electrode (transparent conductive film) side. In addition, a DC output image and a dark output image were obtained when an external electric field was applied to the image pickup device while being irradiated with light from a DC light source, and white scratches and black scratches were evaluated. The evaluation results are shown in Table 1 below.

As shown in Table 1, the larger the amount of foreign matter, the greater the number of defects such as white scratches and black scratches. In Table 1, relative sensitivity and the number of pixel defects are shown with reference to Example 1 in which the content of foreign matter is 0% by mass. For optical sensor applications, the allowable range is at least about 10 times that of Example 1, and the amount of foreign matter in the organic material for forming the light receiving layer is less than 1.0% by mass, preferably 0.8% by mass or less. It was confirmed that it was preferable.

The organic material for film formation and the film forming method using the same of the present invention are applied to an organic imaging device mounted on a digital camera, a camera for a mobile phone, an endoscope camera, an organic EL display, an organic EL illumination, or the like. It can be preferably applied to film formation of an organic layer of an organic photoelectric conversion element used for an organic light emitting element to be mounted, an organic thin film transistor mounted on an electronic paper or a wireless tag, an optical sensor, or the like.

1 Organic photoelectric conversion device (photoelectric conversion device)
10, 101, 210 Substrate 20 Lower electrode 30 Light receiving layer 31 Electron blocking layer 32 Photoelectric conversion layer 40 Upper electrode 50 Sealing layer 60 Vapor deposition material (organic material for film formation)
71 Vapor deposition cell 100 Image sensor, optical sensor 106 Signal readout circuit 200 Organic electroluminescent device 221 Anode 222 Cathode 234 Light emitting layer

Claims (22)

Used for dry film formation of the light-receiving layer of the organic photoelectric conversion element used in the optical sensor,
An organic material for film formation mainly composed of organic substances constituting the light receiving layer,
An organic material for film formation containing less than 1.0% by mass of a substance that cannot be detected by high performance liquid chromatography.   The substance is formed from at least one of a substance generated by the reaction of the constituent organic substance and / or metal, an intermediate generated in the production process of the constituent organic substance, and a substance generated by the reaction of the intermediate. The organic material for film formation according to claim 1.   3. The organic material for film formation according to claim 1, wherein a length of a longer side of one pixel of the photosensor is 5 μm or less.   The organic material for film-forming of any one of Claims 1-3 which contains the said substance 0.8 mass% or less.   The organic material for film-forming of any one of Claims 1-3 which contains the said substance 0.5 mass% or less.   The organic material for film-forming of any one of Claims 1-5 which contain fullerene or a fullerene derivative in the said structure organic substance.   The organic material for film formation according to claim 1, wherein the substance has a sublimation temperature higher than that of the constituent organic substance.   The organic material for film formation according to claim 1, wherein the dry film formation method is a vacuum resistance heating vapor deposition method.   The organic material for film formation according to claim 1, wherein the light receiving layer is a photoelectric conversion layer or an electron blocking layer.   The organic material for film-forming of any one of Claims 1-9 whose residual solvent amount is 3 mol% or less.   The organic material for film formation according to any one of claims 1 to 10, wherein the metal content is less than 10 ppm. A method of forming a light receiving layer of an organic photoelectric conversion element used in an optical sensor by a dry film forming method,
A step of preparing a film-forming organic material having a constituent organic substance of the light-receiving layer as a main component, a purity measured by high performance liquid chromatography of 98% or more, and a metal content of less than 10 ppm;
A purification step of removing a substance that cannot be detected by the high performance liquid chromatography measurement from the organic material for film formation so that the content of the substance in the organic material for film formation is less than 1.0% by mass;
And a film forming step of forming the light receiving layer by the dry film forming method using the organic material for film formation after the purification step.   The substance is at least one of a substance produced by the reaction of the constituent organic substance and / or the metal, an intermediate produced in the production process of the constituent organic substance, and a substance produced by the reaction of the intermediate. The light-receiving layer forming method according to claim 12.   The light-receiving layer forming method according to claim 12, further comprising a step of setting the amount of residual solvent in the organic material for film formation to 3 mol% or less in the purification step. The light-receiving layer forming method according to claim 12, wherein the dry film forming method is a vacuum resistance heating vapor deposition method. The light receiving layer forming method according to claim 12, wherein the light receiving layer is a photoelectric conversion layer or an electron blocking layer. The light- receiving layer forming method according to claim 16, wherein the light-receiving layer is a photoelectric conversion layer or an electron blocking layer, and the constituent organic substance includes fullerene or a fullerene derivative.   The light-receiving layer forming method according to claim 12, wherein the substance has a sublimation temperature higher than that of the constituent organic substance. A method for producing an organic photoelectric conversion element having a pair of electrodes and a light receiving layer or a light emitting layer including at least a photoelectric conversion layer sandwiched between the pair of electrodes,
The manufacturing method of the organic photoelectric conversion element which forms the said light receiving layer with the light receiving layer formation method of any one of Claims 12-18. An organic photoelectric conversion element having a pair of electrodes and a light receiving layer including at least a photoelectric conversion layer sandwiched between the pair of electrodes,
At least one of the pair of electrodes is a transparent electrode,
The organic photoelectric conversion element containing what the said light receiving layer formed into a dry film using the organic material for film-forming of any one of Claims 1-11. A plurality of photoelectric conversion elements according to claim 20;
An optical sensor comprising: a circuit board on which a signal reading circuit for reading a signal corresponding to a charge generated in the photoelectric conversion layer of the photoelectric conversion element is formed.   The optical sensor according to claim 21, wherein the optical sensor is an image sensor.