JP2008053252A - Organic photoelectric conversion element array, and image sensor employing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic photoelectric conversion element array in which crosstalk between the organic photoelectric conversion elements can be suppressed, and to provide an image sensor employing it. <P>SOLUTION: When the organic photoelectric conversion element array A<SB>1</SB>is fabricated having a plurality of organic photoelectric conversion elements 6 arranged on the substrate 1, each of the plurality of organic photoelectric conversion elements 6 is arranged to have a first electrode 2 arranged on the substrate 1, a photoelectric conversion layer 3 arranged on the first electrode 2, a second electrode 4 arranged on the photoelectric conversion layer 3, and a buffer layer 5 arranged between the photoelectric conversion layer 3 and the first electrode 2 or the second electrode 4. At least one of the buffer layer 5 and the photoelectric conversion layer 3 in each individual organic photoelectric conversion element 6 is separated for every organic photoelectric conversion element 6. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an organic photoelectric conversion element array that converts light into electricity using a pn junction or the like made of an organic semiconductor material, and an image sensor using the same.

  Inorganic photoelectric conversion elements using inorganic semiconductor materials are clean devices that do not emit materials when used, and are applied to a wide variety of products such as various image sensors and solar cells including digital cameras and scanners. Yes. However, the inorganic photoelectric conversion element has a problem that it requires a large amount of energy for its production and a large environmental load when it is discarded, and there is an urgent need to solve these problems.

  Under such circumstances, organic photoelectric conversion elements using organic semiconductor materials have begun to attract attention for reasons such as low environmental impact when discarded, low manufacturing costs, and easy area enlargement. Development is underway for practical application.

  For example, Patent Document 1 describes a heterojunction device (pn heterojunction diode) configured by placing a receptor layer in proximity to a conjugated polymer layer as a donor. (Non-Patent Document 1) describes a sensor using an organic photoelectric conversion element.

  The organic photoelectric conversion element converts light into electricity using a pn junction or the like made of an organic semiconductor material. As schematically shown in FIG. 7, the basic structure is a structure in which a first electrode 11, a buffer layer 12, a photoelectric conversion layer 13, and a second electrode 14 are laminated on a substrate 10 in this order. 13 includes an electron donating material layer 15 and an electron accepting material layer 16. When light enters the organic photoelectric conversion element, light absorption occurs in the photoelectric conversion layer 13 to form electron-hole pairs (excitons). The electron-hole pair separates into an electron and a hole in a very short time, the electron passes through the electron-accepting material layer 16 to the second electrode (cathode) 14, and the hole passes through the electron-donating material layer 15. Each moves to one electrode (anode) 11. As a result, an electromotive force is generated between the electrodes 11 and 14. By connecting these electrodes 11 and 14 to an external circuit, it is possible to extract electric power having a magnitude corresponding to the amount of energy of incident light to the organic photoelectric conversion element.

  Such a photoelectric phenomenon is likely to occur at an interface where materials having different electron affinities and ionization potentials are in contact with each other. To produce a highly efficient organic photoelectric conversion element, a plurality of materials having different electron affinities and the like are used. It is necessary to make contact at a wider interface. In addition, from the viewpoint of effectively using carriers (electrons and holes) generated from electron-hole pairs, the separated electrons and holes are transported to each electrode efficiently without recombination. It is desirable to do. Further, it is important to reduce defects in the photoelectric conversion layer so that carriers are not trapped in a defect level or the like or a leak current is not generated.

In order to meet such various demands, research and development of organic photoelectric conversion elements have been intensively studied from both the material side and the process side, and at present, an energy conversion efficiency of about 10% is obtained with the dye sensitizing type. Has reached. Even in the solid thin film type, an energy conversion efficiency of 5% has been obtained by improving the carrier separation efficiency.
JP-T 8-500701 G. Yu, Y. Cao, J .; Wang, J. et al. McElvain and A.M. J. et al. Heeger, Synth. Met. 102, 904 (1999)

  A major feature of the organic photoelectric conversion element is the simplicity of the manufacturing process, and the buffer layer and the photoelectric conversion layer are generally formed by a wet process such as a spin coating method or a dip method. Therefore, even when a plurality of organic photoelectric conversion elements are formed on one substrate, these layers are not patterned and are connected uniformly on the substrate.

  Even in such a configuration, there is no particular problem if the organic photoelectric conversion element may have a large area, such as a solar cell, but when used as a pixel of an image sensor, Carrier movement occurs between the adjacent organic photoelectric conversion elements via the buffer layer and the photoelectric conversion layer, which causes the occurrence of crosstalk.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an organic photoelectric conversion element array in which crosstalk between organic photoelectric conversion elements can be easily suppressed, and an image sensor using the same.

  The organic photoelectric conversion element array of the present invention that achieves the above object is an organic photoelectric conversion element array comprising a substrate and a plurality of organic photoelectric conversion elements arranged on the substrate, and the plurality of organic photoelectric conversion elements Each of the elements includes a first electrode disposed on the substrate, a photoelectric conversion layer disposed on the first electrode, a second electrode disposed on the photoelectric conversion layer, a photoelectric conversion layer, and a first A buffer layer disposed between the electrode and the second electrode, and at least one of the buffer layer and the photoelectric conversion layer in each organic photoelectric conversion element is separated for each organic photoelectric conversion element Features.

  In addition, the image sensor of the present invention that achieves the above object includes an organic photoelectric conversion element array in which a plurality of organic photoelectric conversion elements are arranged on a substrate, and a signal readout that reads an electric signal from each of the plurality of organic photoelectric conversion elements. Each of the plurality of organic photoelectric conversion elements includes a first electrode disposed on a substrate, a photoelectric conversion layer disposed on the first electrode, and the photoelectric conversion layer A second electrode disposed above, and a buffer layer disposed between the photoelectric conversion layer and the first electrode or the second electrode, among the buffer layer and the photoelectric conversion layer in each organic photoelectric conversion element At least one of these is separated for each organic photoelectric conversion element.

  In the organic photoelectric conversion element array of the present invention, since at least one of the buffer layer and the photoelectric conversion layer in each organic photoelectric conversion element is separated for each organic photoelectric conversion element, carriers between the organic photoelectric conversion elements Movement is suppressed. Therefore, according to the present invention, an organic photoelectric conversion element array that can easily suppress crosstalk between organic photoelectric conversion elements can be obtained, and as a result, an image sensor that easily obtains high-quality image data is provided at low cost. Is possible.

  The organic photoelectric conversion element array of the first invention is an organic photoelectric conversion element array comprising a substrate and a plurality of organic photoelectric conversion elements arranged on the substrate, each of the plurality of organic photoelectric conversion elements being The first electrode disposed on the substrate, the photoelectric conversion layer disposed on the first electrode, the second electrode disposed on the photoelectric conversion layer, the photoelectric conversion layer and the first electrode or the second And a buffer layer disposed between the electrodes and at least one of the buffer layer and the photoelectric conversion layer in each organic photoelectric conversion element is separated for each organic photoelectric conversion element.

  In this organic photoelectric conversion element array, since at least one of the buffer layer and the photoelectric conversion layer in each organic photoelectric conversion element is separated for each organic photoelectric conversion element, carriers move between the organic photoelectric conversion elements. As a result, it is easy to suppress crosstalk between the organic photoelectric conversion elements.

  The organic photoelectric conversion element array of 2nd invention is arrange | positioned between the organic photoelectric conversion elements which adjoin mutually, and the electric insulation part which isolate | separates at least one of a buffer layer and a photoelectric conversion layer for every organic photoelectric conversion element It further has these. In this organic photoelectric conversion element array, at least one of the buffer layer and the photoelectric conversion layer in each organic photoelectric conversion element is separated for each organic photoelectric conversion element by the above-described electrical insulating portion. As a result, it becomes easier to suppress crosstalk between the organic photoelectric conversion elements.

  The organic photoelectric conversion element array according to a third aspect of the invention is characterized in that the thickness of the electrical insulating portion is thinner than the thickness of the organic photoelectric conversion element. In this organic photoelectric conversion element array, since the thickness of the electrical insulating portion is thinner than the thickness of the organic photoelectric conversion element, even when a buffer layer or a photoelectric conversion layer is formed by a wet process such as a spin coating method or a dip method. In addition, the film quality and film thickness of the buffer layer or the photoelectric conversion layer are prevented from becoming non-uniform around the electrical insulating portion.

  In the organic photoelectric conversion element array according to the fourth aspect of the invention, the wettability of the solvent in the electrical insulating portion is a layer in which the solvent is electrically separated for each organic photoelectric conversion element among the buffer layer and the photoelectric conversion layer. It is characterized by being lower than the wettability of the solvent in the underlayer with respect to the layer electrically separated for each organic photoelectric conversion element. In this organic photoelectric conversion element array, since the wettability of the solvent in the electrical insulating portion is selected as described above, the buffer layer and the photoelectric conversion layer are formed by a wet process such as a spin coating method or a dip method. Even if the entire surface is coated without selective coating, a buffer layer or a photoelectric conversion layer can be formed at a desired location. Therefore, its manufacture is easy.

  In the organic photoelectric conversion element array according to the fifth aspect of the invention, the surface of the electrical insulating portion is more than the surface of the base layer with respect to the layer electrically separated for each organic photoelectric conversion element among the buffer layer and the photoelectric conversion layer. Is also characterized by high water repellency. Also in this organic photoelectric conversion element array, as in the organic photoelectric conversion element array of the fourth aspect of the present invention, the selective coating is not performed when the buffer layer or the photoelectric conversion layer is formed by the wet process. Even if coating is applied to the entire surface, a buffer layer or a photoelectric conversion layer can be formed at a desired location. Therefore, its manufacture is easy.

  The organic photoelectric conversion element array according to a sixth aspect of the invention is characterized in that the absorption wavelength range of the electrical insulating portion partially overlaps with the absorption wavelength range of the photoelectric conversion layer. In this organic photoelectric conversion element array, since the electrical insulating portion has the above-mentioned light absorption characteristics, each organic photoelectric conversion element has a structure in which separate regions in one photoelectric conversion layer are used as its own photoelectric conversion layer Even in this case, photoelectric conversion is suppressed from occurring outside the region designed as the organic photoelectric conversion element. Moreover, it is also suppressed that light incident on a certain organic photoelectric conversion element is reflected in the element and incident on an adjacent organic photoelectric conversion element, which contributes to photoelectric conversion. As a result of these, the quality of electric signals generated in individual organic photoelectric conversion elements by photoelectric conversion is improved.

  The organic photoelectric conversion element array according to the seventh invention is characterized in that the buffer layer is made of a conductive polymer. In this organic photoelectric conversion element array, since the buffer layer is made of a conductive polymer, the buffer layer can be formed by a wet process such as a spin coating method or a dip method. Therefore, its manufacture is easy.

  The organic photoelectric conversion element array according to the eighth invention is characterized in that the buffer layer contains polyethylenedioxythiophene. In this organic photoelectric conversion element array, since the buffer layer contains polyethylene dioxythiophene, it is easy to obtain an organic photoelectric conversion element with high photoelectric conversion efficiency. Further, if the buffer layer is formed by a wet process using an aqueous dispersion of polyethylene dioxythiophene, the production thereof becomes easy.

  The organic photoelectric conversion element array of the ninth invention is characterized in that the photoelectric conversion layer contains at least one kind of electron donating polymer material and at least one kind of electron accepting material. In this organic photoelectric conversion element array, since the photoelectric conversion layer contains the above-described material, the photoelectric conversion layer can be formed by a wet process such as a spin coating method or a dip method. Therefore, its manufacture is easy.

  An image sensor according to a tenth aspect of the invention includes an organic photoelectric conversion element array in which a plurality of organic photoelectric conversion elements are arranged on a substrate, and a signal reading unit that reads an electric signal from each of the plurality of organic photoelectric conversion elements. Each of the plurality of organic photoelectric conversion elements includes a first electrode disposed on the substrate, a photoelectric conversion layer disposed on the first electrode, and a first electrode disposed on the photoelectric conversion layer. And a buffer layer disposed between the photoelectric conversion layer and the first electrode or the second electrode, and at least one of the buffer layer and the photoelectric conversion layer in each organic photoelectric conversion element is organic photoelectric It is characterized by being separated for each conversion element.

  In this image sensor, since at least one of the buffer layer and the photoelectric conversion layer in each organic photoelectric conversion element constituting the image sensor is separated for each organic photoelectric conversion element, between the organic photoelectric conversion elements Carrier movement is suppressed, and as a result, it is easy to suppress crosstalk between organic photoelectric conversion elements. Therefore, high-quality image data can be easily obtained, and an image sensor having a high modulation amplitude function (MTF) can be easily configured.

  Hereinafter, embodiments of the organic photoelectric conversion element array and the image sensor of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments described below.

(Embodiment 1)
FIG. 1 is a cross-sectional view schematically showing an example of the organic photoelectric conversion element array of the present invention. In the figure, 1 is a substrate, 2 is a first electrode, 3 is a photoelectric conversion layer, 4 is a second electrode, 5 is a buffer layer, 6 is an organic photoelectric conversion element, and A ₁ is an organic photoelectric conversion element array.

In the organic photoelectric conversion element array A ₁ shown in FIG. 1, a plurality of organic photoelectric conversion elements 6 are formed on a substrate 1, and each organic photoelectric conversion element 6 is a first electrode 2 disposed on the substrate 1. The photoelectric conversion layer 3 disposed above the first electrode 2, the second electrode 4 formed on the photoelectric conversion layer 3, and the photoelectric conversion layer 3 and the first electrode 2. And the buffer layer 5. The first electrode 2, the buffer layer 5, the photoelectric conversion layer 3, and the second electrode 4 in each organic photoelectric conversion element 6 are all separated for each organic photoelectric conversion element 6.

  For example, when light enters each organic photoelectric conversion element 6 from the substrate 1 side, light absorption occurs in the photoelectric conversion layer 3 to form electron-hole pairs (excitons). This electron-hole pair is separated into electrons and holes in a very short time, electrons move from the photoelectric conversion layer 3 to the second electrode (cathode) 4, and holes move from the photoelectric conversion layer 3 to the buffer layer 5. To the first electrode (anode) 2. As a result, an electromotive force is generated between the electrodes 2 and 4. By connecting each of the first electrode 2 and the second electrode 4 to an external circuit, an electric signal having a magnitude corresponding to the amount of energy of incident light to the organic photoelectric conversion element 6 can be read out. In order to easily connect each organic photoelectric conversion element 6 to an external circuit, a readout wiring is connected to each of the first electrodes 2 and the second electrodes 4.

For example, as shown in FIG. 2, these read-out wirings include a lead-out direction of the first read-out wiring W ₁ connected to the first electrode 2 and a lead-out direction of the second read-out wiring W ₂ connected to the second electrode 4. Are arranged in different directions. The first readout wiring W ₁ can be formed from the same material together with the first electrode 2 when the first electrode 2 is formed, for example, or can be formed from a material different from the material of the first electrode 2. . The same applies to the second readout wiring W _2. 2 that are the same as those shown in FIG. 1 are assigned the same reference numerals as those used in FIG. 1 and description thereof is omitted.

In the organic photoelectric conversion element array A ₁ having the above-described configuration, all of the first electrode 2, the buffer layer 5, the photoelectric conversion layer 3, and the second electrode 4 in each organic photoelectric conversion element 6 are the organic photoelectric conversion elements 6. Since they are separated from each other, carriers generated in the individual organic photoelectric conversion elements 6 by photoelectric conversion cannot move to other organic photoelectric conversion elements 6. Therefore, it is easy to suppress the crosstalk between the organic photoelectric conversion element array A ₁ in the organic photoelectric conversion element 6. As a result, an electric signal having a magnitude corresponding to the amount of energy of incident light on each organic photoelectric conversion element 6 can be easily read from each organic photoelectric conversion element 6.

The organic photoelectric conversion element array A ₁ having such technical effects can be manufactured, for example, as follows. Hereinafter, an example of a method for manufacturing the organic photoelectric conversion element array A ₁ will be described with reference to the reference numerals used in FIG. 1 or FIG. 2 as appropriate.

  First, a desired number of first electrodes 2 are formed in a predetermined pattern on the substrate 1. At this time, as the substrate 1, substrates of various materials having mechanical and thermal strength can be used. For example, (1) glass, (2) polyethylene terephthalate, polycarbonate, polymethyl methacrylate, polyether sulfone, polyvinyl fluoride, polypropylene, polyethylene, polyacrylate, amorphous polyolefin, fluorine-based resin, and other polymer materials ( 3) Metals such as aluminum (Al), gold (Au), chromium (Cr), copper (Cu), indium (In), magnesium (Mg), nickel (Ni), silicon (Si), titanium (Ti), Or (4) Mg alloy such as Mg-silver (Ag) alloy, Mg-In alloy, Al alloy such as Al-lithium (Li) alloy, Al-strontium (Sr) alloy, Al-barium (Ba) alloy, etc. These alloys can be used as the material of the support substrate 1.

It is also effective to use a flexible substrate obtained by forming the above material into a film or sheet, or a composite substrate obtained by bonding two or more substrates or substrate materials. It is preferred substrate 1 having an electrical insulating property, the range does not interfere with the operation of the organic photoelectric conversion element array A _1, or by the organic photoelectric conversion elements use of the array A _1, electrically conductive Or may include a conductive region.

  For example, the first electrode 2 is formed by forming a metal oxide film, a metal film, an alloy film, or a conductive polymer film on the substrate 1 by a physical vapor deposition method (PVD method) such as a sputtering method. It can be obtained by patterning a film into a desired shape by combining a lithography method (a photolithography method, an electron beam lithography method, etc.) and an etching method. It is also possible to form directly by the PVD method using the vapor deposition mask of a predetermined shape. It is also possible to form the first electrode 2 having a predetermined shape using a lift-off method.

  As the metal oxide film, a film made of indium tin oxide (ITO), antimony-doped tin oxide (ATO), aluminum-doped zinc oxide (AZO), or the like can be used. As the metal film, aluminum Use a film made of (Al), gold (Au), chromium (Cr), copper (Cu), indium (In), magnesium (Mg), nickel (Ni), silicon (Si), titanium (Ti), etc. Can do. As the alloy film, a film made of Mg alloy such as Mg—Ag alloy or Mg—In alloy or Al alloy such as Al—Li alloy, Al—Sr alloy, Al—Ba alloy, or the like is used. it can. As the conductive polymer film, a film made of polyethylenedioxythiophene (PEDOT), polyphenylene vinylene (PPV), polyfluorene, or the like can be used. For example, when using a material with relatively low electrical conductivity such as coating type ITO, one region of the first electrode 2 may be formed with a material with high electrical conductivity, if necessary.

After forming the first electrode 2 as described above, the buffer layer 5, the photoelectric conversion layer 3, and the second electrode 4 are laminated on each first electrode 2 in this order, whereby the organic photoelectric conversion element array A ₁ is obtained.

  The buffer layer 5 is for lowering the series resistance inside the organic photoelectric conversion element 6, and as the material of the buffer layer 5, for example, an oxide of inorganic metal such as molybdenum oxide, or inorganic A metal fluoride, an inorganic metal nitride, or an organic semiconductor such as polyethylenedioxythiophene (PEDOT) or bathocuproine is used.

  The buffer layer 5 is formed, for example, by forming a base layer by a PVD method or a chemical vapor deposition method (CVD method), and then forming this layer by a lithography method (a photolithography method, an electron beam lithography method, etc.) and an etching method. Are combined and patterned into a desired shape. It can also be obtained by patterning the above layer into a desired shape by laser etching. Furthermore, a solution, dispersion, ink, paste, or the like that is a raw material for the buffer layer 5 is applied to a desired shape by a wet process such as a spin coating method, a dip method, a printing method, or an ink jet method, and then subjected to a heat treatment. can get. In consideration of cost reduction, which is one of the characteristics of the organic photoelectric conversion element 6, it is preferable to form the buffer layer 5 by a wet process that does not require a large-scale manufacturing apparatus.

  The photoelectric conversion layer 3 is formed of, for example, a layer containing at least one electron donating material and at least one electron accepting material. This photoelectric conversion layer 3 is made of various vacuum processes such as a vacuum deposition method and a sputtering method, a spin coating method, a dip method, an ink jet method, a printing method, depending on the material or raw material used, the configuration of the photoelectric conversion layer 3, etc. It can be formed by a wet process or the like. If necessary, the photoelectric conversion layer 3 having a predetermined shape is formed by using laser etching, a lift-off method, or the like. In view of cost reduction, which is one of the characteristics of the organic photoelectric conversion element 6, it is preferable to form the photoelectric conversion layer 3 by a wet process that does not require a large-scale manufacturing apparatus.

  As the electron donating material, polymers such as phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, diacetylene and derivatives thereof are used, for example, poly-3-hexylthiophene is preferable. Used for. Further, materials other than polymer materials, for example, (1) porphyrin compounds such as porphine, tetraphenylporphine copper, phthalocyanine, copper phthalocyanine, titanium phthalocyanine oxide, (2) 1,1-bis (4- (di-p-tolylamino) ) Phenyl) cyclohexane, 4,4 ′, 4 ″ -trimethyltriphenylamine, N, N, N ′, N′-tetrakis (p-tolyl) -p-phenylenediamine, 1- (N, N-di-p) -Tolylamino) naphthalene, 4,4'-bis (dimethylamino) -2-2'-dimethyltriphenylmethane, N, N, N ', N'-tetraphenyl-4,4'-diaminobiphenyl, N, N Aromatic tertiary such as' -diphenyl-N, N'-di-m-tolyl-4,4'-diaminobiphenyl, N-phenylcarbazole And stilbene compounds such as (3) 4-di-p-tolylaminostilbene and 4- (di-p-tolylamino) -4 ′-(4- (di-p-tolylamino) styryl) stilbene You can also.

  Furthermore, triazole and its derivatives, oxadiazole and its derivatives, imidazole and its derivatives, polyarylalkane and its derivatives, pyrazoline and its derivatives, pyrazolone and its derivatives, phenylenediamine and its derivatives, arylamine and its derivatives, amino Substituted chalcone and derivatives thereof, oxazole and derivatives thereof, styryl anthracene and derivatives thereof, fluorenone and derivatives thereof, hydrazone and derivatives thereof, silazane and derivatives thereof, polysilane-based aniline-based copolymers, styrylamine compounds, aromatic dimethylidin-based compounds, Poly 3-methylthiophene or the like can also be used.

  On the other hand, the electron-accepting material constituting the photoelectric conversion layer 3 includes (i) fullerenes including C60 and C70, and derivatives thereof, in addition to the same low-molecular or high-molecular materials as the electron-donating material described above. ([5,6] -phenyl C61 butyric acid methyl ester, [6,6] -phenyl C61 butyric acid methyl ester, etc.), (ii) carbon nanotubes and derivatives thereof, (iii) 1,3-bis (4-tert-butyl) Oxadiazole and its derivatives such as phenyl-1,3,4-oxadiazolyl) phenylene, (iv) anthraquinodimethane and its derivatives, (iv) diphenylquinone and its derivatives, etc. are used.

  The second electrode 4 is formed by the same material and method as the first electrode 2 described above. Of the first electrode 2 and the second electrode 4, the electrode positioned on the optical path of the incident light to the organic photoelectric conversion element 6 is appropriately selected as a material or film thickness to be a transparent electrode.

Thus, by forming even the 2nd electrode 4 on the board | substrate 1, the some organic photoelectric conversion element 6 is obtained, and organic photoelectric conversion element array A1 shown in FIG. ₁ is obtained.

(Embodiment 2)
In the organic photoelectric conversion element array of the present invention, an electrical insulating portion is disposed between adjacent organic photoelectric conversion elements, and at least one of the buffer layer and the photoelectric conversion layer in each organic photoelectric conversion element is organic. You may isolate | separate for every photoelectric conversion element.

  FIG. 3 is a cross-sectional view schematically showing an example of an organic photoelectric conversion element array having an electrical insulating portion. Among the constituent members shown in the figure, those that are functionally common to the constituent members shown in FIG. 1 are given the same reference numerals as those used in FIG. 1 and description thereof is omitted.

In the organic photoelectric conversion element array A ₂ shown in FIG. 3, the electrical insulating portion 7 is disposed between the adjacent organic photoelectric conversion elements 6. The electrical insulating portion 7 is formed on the substrate 1, and the thickness thereof is thinner than the thickness of the organic photoelectric conversion element 6. When the substrate 1 is used as a reference, the upper surface of the electrical insulating portion 7 is located above the upper surface of the photoelectric conversion layer 3. Moreover, each organic photoelectric conversion element 6 uses the mutually separate area | region in one electrode film 4A as the self 2nd electrode 4. FIG.

  As the material of the electrical insulating portion 7, a material having electrical insulation capable of suppressing carrier movement between the organic photoelectric conversion elements 6 is used. In particular, the material has mechanical stability and thermal stability. A material that does not affect the photoelectric conversion characteristics of the organic photoelectric conversion element 6 is preferably used. For example, various organic polymer materials such as polyimide are preferably used.

  When the buffer layer 5 and the photoelectric conversion layer 3 are formed by a wet process, the wettability of the solvent with respect to these layers, that is, the wettability of the solvent contained in the raw material composition of these layers is electrically insulated. It is preferable to select the material of the electrical insulating portion 7 so that it is small on the portion 7 and large on the first electrode 2 that is a base layer for the buffer layer 7. For example, when the solvent is water or an organic solvent, the electrical insulating portion 7 is made of a material having higher water repellency than the first electrode 2, for example, various silanes, silicon compounds, or fluorine-based resins such as polytetrafluoroethylene. It is preferable to form.

  When the electrical insulating portion 7 is formed of such a material, the above raw material composition is selectively applied only on the first electrode 2 when the buffer layer 5 and the photoelectric conversion layer 3 are formed by a wet process. Even if it is applied to the entire surface, the raw material composition is repelled by the electrical insulating portion 7, so that the buffer layer 5 and the photoelectric conversion layer 3 separated for each organic photoelectric conversion element 6 are formed. That is, each buffer layer 5 and each photoelectric conversion layer 3 can be easily formed.

  In forming the electrical insulating portion 7, a desired method such as a PVD method, a CVD method, an ink jet method, or a printing method is appropriately selected according to the raw material.

In the organic photoelectric conversion element array A ₂ described above, both the buffer layer 5 and the photoelectric conversion layer 3 in each organic photoelectric conversion element 6 are separated for each organic photoelectric conversion element 6. Therefore, as in the organic photoelectric conversion element array A ₁ described in the first embodiment, carriers generated in individual organic photoelectric conversion elements 6 by photoelectric conversion move to other organic photoelectric conversion elements 6. I can't. For this reason, also in the organic photoelectric conversion element array A _2, it is easy to suppress crosstalk between the organic photoelectric conversion elements 6, and an electric signal having a magnitude corresponding to the energy amount of incident light to each organic photoelectric conversion element 6 is provided. It is easy to read from the organic photoelectric conversion element 6.

Moreover, since each organic photoelectric conversion element 6 uses the mutually separate area | region in one electrode film 4A as the self 2nd electrode 4, formation of the 2nd electrode 4 is easy. Such a formation form of the second electrode 4 is difficult to adopt because the short circuit with the first electrode 2 occurs in the organic photoelectric conversion element array A ₁ (see FIG. 1) described in the first embodiment. This is easy in the organic photoelectric conversion element array A ₂ in which the electrical insulating portion 7 is arranged.

(Embodiment 3)
FIG. 4 is a cross-sectional view schematically illustrating another example of an organic photoelectric conversion element array including an electrical insulating portion. In this figure, the same reference numerals as those used in FIG. 3 are attached to members that are functionally common to the constituent members shown in FIG.

In the organic photoelectric conversion element array A ₃ shown in FIG. 4, an electrical insulating portion 7 having substantially the same thickness as the first electrode 2 is disposed between the adjacent organic photoelectric conversion elements 6, and the electrical insulating portion 7 The buffer layer 5 in each organic photoelectric conversion element 6 is separated for each organic photoelectric conversion element 6. Each organic photoelectric conversion element 6 has its own photoelectric conversion layer 3 as a separate area in one photoelectric conversion film 3A, and has its own second electrode 4 as a separate area in one electrode film 4A. .

  The electrical insulating portion 7 has a mesa shape, and has a trapezoidal vertical cross-sectional shape in which the lower base is longer than the upper base. Similarly, each first electrode 2 also has a mesa shape, and has a trapezoidal vertical cross-sectional shape in which the lower base is longer than the upper base. For this reason, the upper surface of each 1st electrode 2 and the upper surface of the electric insulation part 7 are mutually spaced apart, and the recessed part is formed here. The end portion of each buffer layer 5 on the side of the electric insulating portion 7 is located in the above-described concave portion.

  For example, the electrical insulating portion 7 is formed of a material having a higher water repellency than the first electrode 2 that is a base layer for the buffer layer 5, and the buffer layer 5 is made of a conductive polymer or an organic semiconductor (for example, an aqueous solvent). It is formed by applying a composition in which PEDOT) is dissolved or dispersed and applying heat treatment. Since the electrical insulating portion 7 is rich in water repellency, the composition is not applied selectively only on each first electrode 2 but is applied to the entire surface when applying the composition. A layer is formed only on each first electrode 2 by being repelled by the electrical insulating portion 7. At this time, since each first electrode 2 and the electrical insulating portion 7 have the above-described shape, even when the above composition is applied by a spin coat method, a dip method or the like, The coating amount of is almost the same. For this reason, the buffer layer 5 of substantially the same thickness separated for each organic photoelectric conversion element 6 can be easily formed on each first electrode 2.

In the organic photoelectric conversion element array A ₃ having the above-described configuration, each organic photoelectric conversion element 6 has its own photoelectric conversion layer 3 as a separate area in one photoelectric conversion film 3A. 6 is separated for each organic photoelectric conversion element 6, carriers generated in each organic photoelectric conversion element 6 by photoelectric conversion are unlikely to move to other organic photoelectric conversion elements 6. For this reason, also in the organic photoelectric conversion element array A _3, it is easy to suppress crosstalk between the organic photoelectric conversion elements 6, and each electric signal having a magnitude corresponding to the energy amount of incident light to each organic photoelectric conversion element 6 is transmitted. It is easy to read from the organic photoelectric conversion element 6.

(Embodiment 4)
In the organic photoelectric conversion element array of the present invention, in which an electrical insulating part is disposed between adjacent organic photoelectric conversion elements, the absorption wavelength range of the electrical insulating part and the absorption wavelength range of the photoelectric conversion layer are determined. Some can be duplicated.

  For example, by appropriately selecting the material of the electrical insulating part according to the absorption wavelength range in the photoelectric conversion layer, or by appropriately using a desired colorant as the material of the electrical insulating part, the absorption wavelength range is changed to the photoelectric conversion layer. It is possible to form an electrically insulating portion that partially overlaps the absorption wavelength region.

  When the organic photoelectric conversion element array is configured in this way, each organic photoelectric conversion element has its own photoelectric conversion layer in a single photoelectric conversion film as in the organic photoelectric conversion element array described in the third embodiment. Even in this case, a part of the light in the wavelength region contributing to the photoelectric conversion out of the light incident on the organic photoelectric conversion element array from the substrate side is absorbed by the electric insulating part, so that the photoelectric conversion film on the electric insulating part The photoelectric conversion at is suppressed. In addition, among the light incident on each organic photoelectric conversion element, light that repeats reflection inside the element and leaks to the other organic photoelectric conversion element side (hereinafter, referred to as “leakage light”) is caused by the electrical insulating portion. The amount of light absorbed can be reduced.

  As a result of these, in addition to suppressing crosstalk between organic photoelectric conversion elements, generation of carriers in areas other than areas designed as organic photoelectric conversion elements and generation of carriers due to leakage light are suppressed, The quality of electrical signals generated in individual organic photoelectric conversion elements by photoelectric conversion is improved.

(Embodiment 5)
The photoelectric conversion layer constituting the organic photoelectric conversion element in the organic photoelectric conversion element array of the present invention can be formed by a dry process, for example, by co-evaporation of an organic material, but a large-scale apparatus is not required for cost reduction. It is preferably formed by a wet process such as a spin coating method, an ink jet method, or a spray method.

  In this case, it is preferable to use an organic polymer material for at least a part of the material of the photoelectric conversion layer. Then, a photoelectric conversion layer is formed by a wet process using the solution or dispersion of the organic polymer material. Since the viscosity of the organic polymer material solution or dispersion liquid can be easily adjusted as compared with the organic low molecular material solution or dispersion liquid, the film thickness after film formation can be easily controlled. For example, when a photoelectric conversion layer is formed only with an organic polymer material, it becomes easier to form a photoelectric conversion layer having excellent thermal stability as compared with a case where an organic low molecular material is used in combination.

  In order to obtain an organic photoelectric conversion element having high photoelectric conversion efficiency, it is preferable that the photoelectric conversion layer contains at least one electron donating material and at least one electron accepting material. In forming the conversion layer by a wet process, it is particularly preferable that at least one of the electron donating material and the electron accepting material is an organic polymer material.

  For example, like the photoelectric conversion layer 3 shown in FIG. 5, the photoelectric conversion layer 3 including a layer in which the electron-accepting material 9 is dispersed in the electron-donating polymer material 8 can be easily formed by a wet process. A composite material in which an electron-accepting material 9 such as fullerenes or carbon nanotubes is dispersed in the electron-donating polymer material 8 is very much between the electron-donating polymer material 8 and the electron-accepting material 9. Since a good pn junction is formed, it is suitable as a material for the photoelectric conversion layer 3. In particular, substances in which fullerene is chemically modified, such as [5,6] -phenyl C61 butyric acid methyl ester and [6,6] -phenyl C61 butyric acid methyl ester, are dispersible to the electron donating polymer material 8 in a solvent. Is favorable for obtaining the photoelectric conversion layer 3 in which the electron-accepting material 9 is uniformly dispersed by a wet process. 5 that are the same as those shown in FIG. 1 are assigned the same reference numerals as those used in FIG. 1, and descriptions thereof are omitted.

(Embodiment 6)
The image sensor of the present invention includes an organic photoelectric conversion element array in which a plurality of organic photoelectric conversion elements are arranged on a substrate, and a signal reading unit that reads an electric signal from each of the plurality of organic photoelectric conversion elements. The organic photoelectric conversion element array in the image sensor is the organic photoelectric conversion element array of the present invention. That is, the individual organic photoelectric conversion elements in this organic photoelectric conversion element array are arranged on the first electrode arranged on the substrate, the photoelectric conversion layer arranged on the first electrode, and the photoelectric conversion layer. And a buffer layer disposed between the photoelectric conversion layer and the first electrode or the second electrode, and at least one of the buffer layer and the photoelectric conversion layer in each organic photoelectric conversion element is organic. Separated for each photoelectric conversion element.

  The image sensor of the present invention may be a linear image sensor or an area image sensor. In the case where the image sensor of the present invention is a linear image sensor, organic photoelectric conversion elements are arranged on a substrate over a 1-row multiple column, a 3-row multiple column, or a 4-row multiple column. If necessary, it is also possible to arrange the organic photoelectric conversion elements over two rows and many columns on the substrate. In the case where the image sensor of the present invention is an area image sensor, organic photoelectric conversion elements are arranged on a substrate over many rows and many columns.

  FIG. 6 is a perspective view schematically showing an example of the image sensor of the present invention. An image sensor S shown in FIG. 1 is a linear image sensor, and organic photoelectric conversion elements 6 are arranged on a substrate 1 over one row and many columns. Each organic photoelectric conversion element has a separate region in one photoelectric conversion film 3A as its own photoelectric conversion layer 3 and a separate region in one electrode film 4A as its own second electrode 4, The buffer layer 5 in the organic photoelectric conversion element 6 is separated for each organic photoelectric conversion element 6. An electrical insulating portion 7 a is arranged between the adjacent organic photoelectric conversion elements 6, and the electrical insulating layer 7 a is provided with the buffer layer 5 in each organic photoelectric conversion element 6 for each organic photoelectric conversion element 6. It is not directly related to the separation.

  In FIG. 6, signal reading means for reading an electric signal from each of the organic photoelectric conversion elements 6 is not shown. The signal reading means includes, for example, a semiconductor chip in which a predetermined integrated circuit is formed, and a plurality of read wirings connected to the first electrode 2 one by one and connecting the semiconductor chip and each first electrode 2. It is comprised including.

  The image sensor S having such a configuration constitutes an information reading device in combination with each of the light source unit and the predetermined optical system. In this information reading apparatus, reflected light or direct light from an object to be read such as a document enters the substrate 1 via a predetermined optical system and then enters each organic photoelectric conversion element 6. Thereby, an electric signal having a magnitude corresponding to the amount of energy of incident light is generated in each organic photoelectric conversion element 6. Then, an electrical signal generated in each organic photoelectric conversion element 6 is transmitted to the integrated circuit on the semiconductor chip via the readout wiring, and predetermined image data is generated here.

  As already described, since the cross-talk between the organic photoelectric conversion elements can be easily suppressed in the organic photoelectric conversion element array of the present invention, the image sensor of the present invention including the organic photoelectric conversion element array has high quality. The image data can be easily obtained. It is also easy to construct an image sensor with a high modulation amplitude function (MTF), that is, an image sensor with high contrast reproducibility.

  As mentioned above, although each embodiment of the organic photoelectric conversion element array and image sensor of this invention was explained in full detail, this invention is not limited to these forms as mentioned above.

  For example, the organic photoelectric conversion element arrays or image sensors described in Embodiments 1 to 6 are all premised on performing photoelectric conversion by light incident from the substrate side, but on the opposite side of the substrate An organic photoelectric conversion element array or an image sensor can also be configured on the premise that photoelectric conversion is performed with light incident from. In this case, for example, the polarities of the first electrode 2 and the second electrode 4 shown in FIG. 1 are reversed, and the second electrode 4 is a transparent electrode.

  The buffer layer may be interposed between at least one of a pair of electrodes (first electrode and second electrode) constituting the organic photoelectric conversion element and the photoelectric conversion layer. In the case where a buffer layer is interposed between the electrode used as the positive electrode of the pair of electrodes and the photoelectric conversion layer, the buffer layer has a higher work function than the electron-accepting material constituting the photoelectric conversion layer. At the same time, it is preferably formed of a material having a work function lower than that of the positive electrode. In addition, when a buffer layer is interposed between the electrode used as the negative electrode of the pair of electrodes and the photoelectric conversion layer, the buffer layer has a lower work function than the electron donating material constituting the photoelectric conversion layer. And a material having a work function higher than that of the negative electrode.

  When only one of the buffer layer and the photoelectric conversion layer in each organic photoelectric conversion element is electrically separated for each organic photoelectric conversion element, which of the buffer layer and the photoelectric conversion layer is separated It can be appropriately selected according to the arrangement. For example, when a buffer layer is stacked on the photoelectric conversion layer, it is easier to separate the photoelectric conversion layer than to separate the buffer layer.

  In the case where an electrical insulating part is disposed between organic photoelectric conversion elements that are close to each other, an electrode located on the substrate side among a pair of electrodes in each organic photoelectric conversion element may be in contact with the electrical insulating part. Then, it may be separated from the electrical insulation part, or the end part may be partially covered by the electrical insulation part.

  When a plurality of organic photoelectric conversion elements are arranged two-dimensionally (many rows and many columns) on a substrate, for example, on a multilayer wiring substrate (including an interposer substrate) on which a predetermined number of readout wirings are formed. It is necessary to devise the arrangement of each organic photoelectric conversion element and the readout wiring for the organic photoelectric conversion element, such as arranging each organic photoelectric conversion element.

  The organic photoelectric conversion element array and image sensor of the present invention can be variously modified, modified, combined, etc. in addition to those described above. Hereinafter, specific examples of the present invention will be described with reference to examples.

  First, an ITO film having a thickness of 150 nm is formed on a glass substrate by a sputtering method, and a resist material (OFPR-800 (trade name) manufactured by Tokyo Ohka Kogyo Co., Ltd.) is applied on the ITO film by a spin coating method to obtain a thickness. After forming a 5 μm resist film, the resist film was selectively exposed and developed to obtain a resist pattern having a predetermined shape. Then, after immersing the glass substrate formed up to the resist pattern in an 18N aqueous hydrochloric acid solution having a liquid temperature of 60 ° C. to etch a portion of the ITO film where the resist pattern is not formed, a rinse treatment with pure water is performed. The resist pattern was removed to obtain a number of first electrodes (positive electrodes) made of an ITO film having a predetermined shape.

  Next, the glass substrate on which the first electrode is formed is washed with an alkaline detergent and dried, and then a film made of fluoroalkylsilane is formed on the surface on which the first electrode is formed, and the first electrode adjacent to each other is formed. The film was patterned so as to remain only between one electrode. Thereby, a water-repellent electrical insulating portion was formed between the first electrodes adjacent to each other.

  Next, an aqueous dispersion of polyethylene dioxythiophene (PEDOT) was prepared, and the aqueous dispersion was spin-coated on the surface on which the electrical insulating portion was formed, and then heat-treated at 200 ° C. for 10 minutes. A 60 nm buffer layer was formed. Since the aqueous dispersion is repelled by the water-repellent electrical insulating portion, the buffer layer is formed only in the region where the electrical insulating film is not formed.

  Subsequently, poly (2-methoxy-5- (2′-ethylhexyloxy) -1,4-phenylenevinylene) (hereinafter abbreviated as “MEH-PPV”) and an electron functioning as an electricity-donating polymer material. Spin coating a chlorobenzene solution containing [6,6] -phenyl C61 butyric acid methyl ester (hereinafter abbreviated as “[6,6] -PCBM”) that functions as a receptive material in a weight ratio of 1: 4. And the photoelectric conversion film about 100 nm thick was formed by heat-processing for 30 minutes in 100 degreeC clean oven. This photoelectric conversion layer covers each buffer layer.

  [6, 6] -PCBM is a chemically modified fullerene and is well dispersed in chlorobenzene, which is a solvent for MEH-PPV, and thus is suitable for forming a homogeneous photoelectric conversion layer. In addition, since the electron accepting property is very high, carriers can be efficiently delivered to and from MEH-PPV which is an electron donating polymer material, and thereby excellent photoelectric conversion efficiency can be obtained.

The glass substrate formed up to the photoelectric conversion film as described above is put into a resistance heating vapor deposition apparatus, and after reducing the pressure to 0.27 mPa (2 × 10 ⁻⁶ Torr) or less, from aluminum on the photoelectric conversion film. An electrode film having a thickness of about 100 nm was formed.

Thus, by forming even an electrode film, many organic photoelectric conversion elements were formed on the glass substrate, and the organic photoelectric conversion element array was obtained. As in the organic photoelectric conversion element array A ₃ shown in FIG. 4, each organic photoelectric conversion element has its own photoelectric conversion layer as a separate area in the photoelectric conversion film, and each other in the electrode film. The separate area | region is made into the self 2nd electrode, and the buffer layer in each organic photoelectric conversion element is isolate | separated for every organic photoelectric conversion element by the electrical insulation part.

  In the organic photoelectric conversion element array of the present invention, since at least one of the buffer layer and the photoelectric conversion layer in each organic photoelectric conversion element is separated for each organic photoelectric conversion element, between the organic photoelectric conversion elements Since it is easy to suppress the movement of the carrier and thereby the crosstalk, it is possible to obtain high-quality image data and to provide the image sensor at low cost by using it as a photoelectric conversion element array in an image sensor, for example. Become.

Sectional drawing which shows schematically an example of the organic photoelectric conversion element array of this invention The perspective view which shows roughly an example of arrangement | positioning of the read-out wiring for connecting each organic photoelectric conversion element in the organic photoelectric conversion element array of this invention to an external circuit Sectional drawing which shows roughly an example of the thing provided with the electrical-insulation part among the organic photoelectric conversion element arrays of this invention Sectional drawing which shows schematically the other example of the thing provided with the electrical-insulation part among the organic photoelectric conversion element arrays of this invention Sectional drawing which shows schematically an example of what consists of a layer by which the electron-accepting material was disperse | distributed to the electron-donating polymeric material among the photoelectric converting layers which comprise the organic photoelectric conversion element array of this invention The perspective view which shows an example of the image sensor of this invention roughly Sectional drawing which shows the basic structure of an organic photoelectric conversion element roughly

Explanation of symbols

1 substrate 2 first electrode 3 photoelectric conversion layer 4 second electrode 5 buffer layer 6 organic photoelectric conversion element 7 electrically insulating portion 8 electron donating polymer material 9 electron accepting material A ₁ to A ₄ organic photoelectric conversion element array S Image Sensor W ₁ first readout wiring W ₂ second readout wiring

Claims (10)

An organic photoelectric conversion element array comprising a substrate and a plurality of organic photoelectric conversion elements arranged on the substrate,
Each of the plurality of organic photoelectric conversion elements includes a first electrode disposed on the substrate, a photoelectric conversion layer disposed on the first electrode, and a second electrode disposed on the photoelectric conversion layer, A buffer layer disposed between the photoelectric conversion layer and the first electrode or the second electrode;
An organic photoelectric conversion element array, wherein at least one of the buffer layer and the photoelectric conversion layer in each organic photoelectric conversion element is separated for each organic photoelectric conversion element. An electrical insulating part that is disposed between adjacent organic photoelectric conversion elements and separates at least one of the buffer layer and the photoelectric conversion layer for each organic photoelectric conversion element. 2. The organic photoelectric conversion element array according to 1. The organic photoelectric conversion element array according to claim 2, wherein a thickness of the electrical insulating portion is smaller than a thickness of the organic photoelectric conversion element. The wettability of the solvent in the electrical insulating portion is determined for each organic photoelectric conversion element when the solvent is a solvent for a layer separated for each organic photoelectric conversion element among the buffer layer and the photoelectric conversion layer. The organic photoelectric conversion element array according to claim 2 or 3, wherein the organic photoelectric conversion element array is lower than the wettability of the solvent in the base layer with respect to the separated layer. The surface of the electrical insulating part is richer in water repellency than the surface of the underlayer for the layer separated for each organic photoelectric conversion element among the buffer layer and the photoelectric conversion layer. The organic photoelectric conversion element array according to any one of 4. The organic photoelectric conversion element array according to any one of claims 2 to 5, wherein an absorption wavelength range of the electrical insulating part partially overlaps with an absorption wavelength range of the photoelectric conversion layer. The organic photoelectric conversion element array according to claim 1, wherein the buffer layer is made of a conductive polymer. The organic photoelectric conversion element array according to claim 1, wherein the buffer layer contains polyethylene dioxythiophene. The organic material according to claim 1, wherein the photoelectric conversion layer contains at least one electron donating polymer material and at least one electron accepting material. Photoelectric conversion element array. An image sensor comprising: an organic photoelectric conversion element array in which a plurality of organic photoelectric conversion elements are arranged on a substrate; and a signal reading unit that reads an electric signal from each of the plurality of organic photoelectric conversion elements,
Each of the plurality of organic photoelectric conversion elements includes a first electrode disposed on the substrate, a photoelectric conversion layer disposed on the first electrode, and a second electrode disposed on the photoelectric conversion layer, A buffer layer disposed between the photoelectric conversion layer and the first electrode or the second electrode;
At least one of the buffer layer and the photoelectric conversion layer in each organic photoelectric conversion element is separated for each organic photoelectric conversion element.

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