JP2018195683A - Sold state imaging device - Google Patents

Abstract

To provide a solid state imaging device having high quantum efficiency, excellent light absorbency, and fast optical response speed in a wide range of light intensity.SOLUTION: The sold state imaging device is provided that comprises a photoelectric conversion element which includes: a photoelectric conversion layer photoelectrically converting incident light; a hole transport layer transporting a hole to the photoelectric conversion layer; an electron transport layer transporting an electron to the photoelectric conversion layer; and a pair of electrodes. The photoelectric conversion layer, the hole transport layer, and the electron transport layer are laminated between the pair of electrodes. The photoelectric conversion layer includes a material having three-dimensional perovskite structure.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a solid-state imaging device.

  Conventionally, as a solid-state imaging device which is a semiconductor image sensor, a planar solid-state imaging device in which photodiodes are two-dimensionally arranged on a semiconductor substrate such as silicon and signal charges generated by each photodiode are read by a circuit is widely used. It has been.

  In order to realize a color solid-state imaging device, a structure in which a color filter that transmits light of a specific wavelength is arranged on the light incident surface side of the flat-type solid-state imaging device is generally used. For example, color filters that transmit blue (B) light, green (G) light, and red (R) light are regularly arranged on two-dimensionally arranged photodiodes widely used in digital cameras and the like. A single-plate solid-state imaging device is well known.

  In recent years, there has been a demand for pixel miniaturization of solid-state imaging devices that contributes to further development of image sensors. However, silicon photodiodes have a problem in that sensitivity is lowered as a result of narrowing the light receiving area so that light does not enter the transistors and the like due to the presence of transistors and the like as signal readout portions. In addition, silicon photodiodes require a thickness in the depth direction to compensate for the disadvantage of low absorption sensitivity on the long wavelength side. As a result, the incident angle of the light beam is limited so that it can reach the deep part, and light is efficiently transmitted. It was not possible to use it, which prevented the pixel from being miniaturized. Furthermore, in recent years, development of a solid-state imaging device having a structure in which an organic photoelectric conversion film is formed on a signal readout substrate has been advanced. In the solid-state imaging device using such an organic photoelectric conversion film, improvement of photoelectric conversion efficiency, response speed, and reduction of dark current are particularly problematic.

  In addition, among the needs for applying the device to various applications, it is sometimes required to maintain various characteristics as a solid-state imaging device even if the device is placed in a high temperature environment (for example, 90 ° C.) for a long time. is there. That is, there are cases where excellent heat resistance is required for the solid-state imaging device.

  For example, in Patent Document 1, a conductive film, a photoelectric conversion film containing a photoelectric conversion material, and a transparent conductive film are arranged in this order in order to provide a photoelectric conversion element excellent in responsiveness and high-temperature storage stability. A photoelectric conversion element comprising a predetermined compound (A) having a structure in which an amine moiety and an acidic nucleus moiety are linked by a linking moiety containing thiophene, and the amine moiety and the linking moiety are condensed. In addition, an image sensor including the photoelectric conversion element has been proposed.

JP 2014-82483 A

  However, when the present inventors examined conventional solid-state image sensors including the image sensor described in Patent Document 1, the conventional solid-state image sensor has high quantum efficiency, good light absorption, and a wide range. From the viewpoint of fast light response speed at a high light intensity, it has been found that there is room for further improvement.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a solid-state imaging device having high quantum efficiency, good light absorption, and high light response speed in a wide range of light intensity. is there.

  As a result of intensive studies to achieve the above object, the present inventors have used a specific substance for the photoelectric conversion layer, so that the quantum efficiency is increased, the light absorptivity is improved, and the light intensity is wide. The inventors have found that the light response speed is increased, and have completed the present invention.

That is, the solid-state imaging device of the present invention is as follows.
[1] A photoelectric conversion layer that photoelectrically converts incident light, a hole transport layer that transports holes to the photoelectric conversion layer, an electron transport layer that transports electrons to the photoelectric conversion layer, and a pair of A solid-state imaging device including a photoelectric conversion element including an electrode, wherein the photoelectric conversion layer, the hole transport layer, and the electron transport layer are stacked between the pair of electrodes, and the photoelectric conversion layer is A solid-state imaging device comprising a material having a three-dimensional perovskite structure.
[2] The solid-state imaging device according to [1], wherein a plurality of pixels are configured by two-dimensionally arranging at least one of the pair of electrodes.
[3] The solid-state imaging according to [1] or [2], in which a plurality of pixels are configured by two-dimensionally arranging one of the pair of electrodes with respect to one photoelectric conversion layer. element.
[4] The solid-state imaging device according to any one of [1] to [3], further including a color filter on one of the pair of electrodes.

  According to the present invention, it is possible to provide a solid-state imaging device having high quantum efficiency, good light absorption, and high light response speed in a wide range of light intensity.

It is a cross-sectional schematic diagram which partially shows an example of the solid-state image sensor of this invention. It is a cross-sectional schematic diagram which partially shows another example of the solid-state image sensor of this invention. It is a cross-sectional schematic diagram which partially shows another example of the solid-state image sensor of this invention.

  Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail with reference to the drawings as necessary. However, the present invention is limited to the following embodiment. It is not a thing. The present invention can be variously modified without departing from the gist thereof. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

(Solid-state imaging device)
The solid-state imaging device of this embodiment includes a photoelectric conversion layer that photoelectrically converts incident light, a hole transport layer that transports holes to the photoelectric conversion layer, and an electron transport layer that transports electrons to the photoelectric conversion layer. A solid-state imaging device comprising a photoelectric conversion element including a pair of electrodes, wherein the photoelectric conversion layer, the hole transport layer, and the electron transport layer are stacked between the pair of electrodes, It includes a material having a three-dimensional perovskite structure. A solid-state image sensor is an element that converts optical information of an image into an electrical signal. The solid-state imaging device according to the present embodiment has a high quantum efficiency, good light absorption, and a light response in a wide range of light intensity mainly because the photoelectric conversion layer includes a material having a three-dimensional perovskite structure. Speed can be increased. Although the cause is not clarified in detail, the present inventors consider as follows. However, the factors are not limited to the following.

  That is, a material having a perovskite structure shows that the crystal exhibits strong light absorption by band gap excitation as a compound semiconductor, and free carriers generated by photoexcitation in the perovskite crystal are stable (long life) and the carrier moving distance. It is considered that the fact that the ratio of the voltage loss lost as heat is small due to the long period of time leads to excellent characteristics as compared with the conventional element described in Patent Document 1. In particular, the material having a three-dimensional perovskite structure in the present embodiment has a crystal structure that is continuous in a direction orthogonal to the stacking direction of the photoelectric conversion film, thereby suppressing loss of carrier movement in the layer and more excellent. It is thought that it shows the characteristic.

  FIG. 1 is a schematic cross-sectional view partially showing an example of the solid-state imaging device of the present embodiment. A solid-state imaging device 100 illustrated in FIG. 1 includes a photoelectric conversion layer 110 including a material having a three-dimensional perovskite structure, and a hole transport layer 120 and an electron transport layer 130 that are stacked so as to sandwich the photoelectric conversion layer 110. The transparent electrode 140 and the counter electrode 150 are stacked so as to further sandwich them. The solid-state imaging device 100 mainly has a photoelectric conversion layer containing a material having a three-dimensional perovskite structure, thereby increasing quantum efficiency, improving light absorption, and providing a light response speed in a wide range of light intensities. Can be fast. Hereinafter, each member provided in the solid-state imaging device 100 will be described in detail.

(Photoelectric conversion layer)
The photoelectric conversion layer according to this embodiment is a layer that converts light energy into electrical energy. The photoelectric conversion layer is not particularly limited as long as it includes a material having a three-dimensional perovskite structure. This material is distinguished from one having a so-called layered (two-dimensional) perovskite structure. A material having a two-dimensional perovskite structure has a self-organized structure in which a certain cation layer and another cation layer are alternately stacked. On the other hand, a material having a three-dimensional perovskite structure has two cation layers that are not clearly distinguished.

  The material having a three-dimensional perovskite structure is not particularly limited, but a halide-based perovskite compound is preferable from the viewpoint of more effectively and reliably achieving the effects of the present invention. A halide-based perovskite compound functions as a light absorber and self-dielectrically acts as a ferroelectric substance to cause charge separation, and thus exhibits a characteristic as a photoelectric conversion layer alone.

The halide perovskite compound is a perovskite compound having a halide ion as an anion and at least two kinds of cations as a cation. The basic structural form of perovskite is the ABX ₃ structure, which has a three-dimensional network of vertex shared BX ₆ octahedrons. The B component in the ABX ₃ structure is a metal cation capable of taking octahedral coordination of the X anion. A cations are located in 12 coordination holes between BX ₆ octahedra. By using A as an appropriate cation, a material having a three-dimensional perovskite structure is formed.

The halide perovskite compound according to this embodiment is a compound represented by the following formula (1).
RM ¹ X ₃ (1)
In the formula (1), R represents a monovalent cation such that the compound represented by the formula (1) has a three-dimensional perovskite structure, and M ¹ represents a divalent metal ion. , X represents one or more selected from the group consisting of fluoride ions (F ⁻ ), chloride ions (Cl ⁻ ), bromide ions (Br ⁻ ), and iodide ions (I ⁻ ).

R is one or more selected from the group consisting of CH ₃ NH ₃ ⁺ , NH ₂ CH═NH ₂ ⁺ , Cs ^+, and Rb ⁺ from the viewpoint of more effectively and reliably achieving the effects of the present invention. preferably when ^{_{there, CH 3 NH 3 +, +}} NH 2 CH = NH 2, Cs +, Rb +, the combination of the CH ₃ NH ₃ ⁺ and ^{_{NH 2 CH = NH 2 +,}} CH 3 NH 3 + and Cs ⁺ and A combination of NH ₂ CH═NH ₂ ⁺ and Cs ⁺ , a combination of CH ₃ NH ₃ ⁺ and NH ₂ CH═NH ₂ ⁺ and Cs ⁺ , a combination of CH ₃ NH ₃ ⁺ and Rb ⁺ , NH ₂ CH = NH ₂ ⁺ and Rb ⁺ are more preferable, or CH ₃ NH ₃ ⁺ , NH ₂ CH═NH ₂ ⁺ and Rb ⁺ are more preferable.

The structure of the halide-based perovskite compound according to the present embodiment has a metal halide octahedron layer sharing a vertex. For balancing the positive charge from the cationic organic layers, the anionic metal halide layers _{^{(e.g., M 1 X 3 -, M}} 1 X 4 2-) M 1 in the normal divalent metal ions It is.

Examples of the metal ion (M ¹ ) constituting the anionic metal halide layer of the halide-based perovskite compound according to this embodiment include Cu ²⁺ , Ni ²⁺ , Mn ²⁺ , Fe ²⁺ , and Co ^2+. , Pd ²⁺ , Ge ²⁺ , Sn ²⁺ , Pb ²⁺ , Bi ²⁺ and Eu ²⁺ . Among these, Pb ²⁺ , Sn ²⁺ and Bi ²⁺ are preferable, and Pb ²⁺ is more preferable from the viewpoint of more effectively and reliably achieving the effects of the present invention. These are used singly or in combination of two or more.

  Examples of the halide ions constituting the anionic metal halide layer of the halide-based perovskite compound according to the present embodiment include fluoride ions, chloride ions, bromide ions, and iodide ions as described above. Among these, bromide ions and iodide ions are preferable from the viewpoint of more effectively and reliably achieving the effects of the present invention. These are used singly or in combination of two or more.

Specific examples of the halide-based perovskite compound according to this embodiment include MAPbX ₃ , FAPbX ₃ , (FAPbX ₃ ) _y (MAPbX ₃ ) _1-y, and Cs _x (MA _0.17 FA _0.83 ) _1-x Pb (X ¹ _0.83 X ² _0.17 ) ₃ . Here, “MA” represents CH ₃ NH ₃ ⁺ , “FA” represents NH ₂ CH═NH ₂ ⁺ , and X, X ¹ and X ² are fluoride ions (F ⁻ ) and chloride ions (Cl ^-), bromide ion (Br ^-) and iodide ions (I ^- represents one or more members selected from the group consisting of), X ¹ and X ² are different from each other. More specifically, MAPbI ₃ , MAPbBr ₃ , FAPbI ₃ , (FAPbI ₃ ) _0.95 (MAPbBr ₃ ) _0.05 and Cs _x (MA _0.17 FA _0.83 ) _1-x Pb (I _0.83 Br _0.17 ) ₃ may be mentioned.

  The thickness of the photoelectric conversion layer is not particularly limited, but it is preferably 1 nm or more and 1000 nm or less, more preferably 100 nm or more and 700 nm or less, and more preferably 200 nm or more and 600 nm from the viewpoint of more effectively and reliably achieving the effects of the present invention. More preferably, it is as follows.

The photoelectric conversion layer according to the present embodiment desirably absorbs light in the infrared wavelength region in addition to the visible light region from the viewpoint of the large amount of optical information and the large amount of light that can be obtained by the solid-state imaging device. That is, the absorption edge wavelength on the long wavelength side of the light absorption wavelength is preferably 800 nm or more, more preferably 900 nm or more, and further preferably 1000 nm or more.
The absorption edge on the long wavelength side of the light absorption wavelength can be controlled within the above range by appropriately changing the composition of each ion contained in the photoelectric conversion layer and the composition ratio thereof.

  The method for forming the photoelectric conversion layer is not particularly limited, but when the material having a three-dimensional perovskite structure is a halide-based perovskite compound, the compound can be synthesized by a self-assembly reaction using a precursor solution. . In this case, the photoelectric conversion layer is formed by dissolving a halide-based perovskite compound in an organic solvent and then applying a gravure coating method, a bar coating method, a screen printing method, a spray method, a spin coating method, a dip method, a die coating method, or the like. it can. It is also possible to form a film by a vacuum deposition method.

  The solvent for preparing the solution of the halide perovskite compound is not particularly limited as long as it can dissolve the compound. Examples of such solvents include esters (eg, methyl formate, ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, pentyl acetate, etc.), ketones (eg, γ-butyrolactone, N methyl-2-pyrrolidone, acetone, dimethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, etc.), ethers (eg, diethyl ether, methyl-tert-butyl ether, diisopropyl ether, dimethoxymethane, dimethoxyethane, 1 , 4-dioxane, 1,3-dioxolane, 4-methyldioxolane, tetrahydrofuran, methyltetrahydrofuran, anisole, phenetol, etc.), alcohols (eg, methanol, ethanol, -Propanol, 2-propanol, 1-butanol, 2-butanol, tert-butanol, 1-pentanol, 2-methyl-2-butanol, methoxypropanol, diacetone alcohol, cyclohexanol, 2-fluoroethanol, 2,2 , 2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol, etc.), glycol ethers (cellosolves) (eg, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene Glycol monoethyl ether acetate, triethylene glycol dimethyl ether, etc.), amide solvents (eg, N, N-dimethylformamide, acetamide, N, N-dimethylacetamide, etc.), nitrile solvents Agents (eg, acetonitrile, isobutyronitrile, propionitrile, methoxyacetonitrile, etc.), carboat agents (eg, ethylene carbonate, propylene carbonate, etc.), halogenated hydrocarbons (eg, methylene chloride, dichloromethane, chloroform, etc.), Examples include hydrocarbons (eg, n-pentane, cyclohexane, n-hexane, benzene, toluene, xylene, etc.), and dimethyl sulfoxide. The compound used for these solvents may have a branched structure or a cyclic structure. In addition, the compound used for the solvent has two or more functional groups of esters, ketones, ethers and alcohols (that is, —O—, —CO—, —COO— and —OH). It may be. The hydrogen atom in the hydrocarbon moiety of the esters, ketones, ethers and alcohols may be substituted with a halogen atom (particularly a fluorine atom).

(Hole transport layer)
The solid-state imaging device of this embodiment has a hole transport layer between the photoelectric conversion layer and the transparent electrode so that charges (holes) generated in the photoelectric conversion layer can be efficiently transported by the transparent electrode. . The hole transport layer is not particularly limited as long as it is known as a hole transport layer in a photoelectric conversion element such as a solid-state imaging element. For example, polyaniline and its doped material, International Publication No. 2006/019270. And the described cyanide compounds. More specifically, for example, iodide such as selenium and copper iodide (CuI), cobalt complex such as layered cobalt oxide, CuSCN, molybdenum oxide (MoO ₃ etc.), nickel oxide (NiO etc.), 4CuBr · 3S (C ₄ H ₉ ) and organic hole transport materials. Among these, examples of the iodide include copper iodide (CuI). Examples of the layered cobalt oxide include A _x CoO ₂ (where A represents Li, Na, K, Ca, Sr, or Ba, and 0 ≦ X ≦ 1). Moreover, as an organic hole transport material, for example, poly-3-hexylthiophene (P3HT), poly (3,4-ethylenedioxythiophene), (PEDOT; for example, trade name “BaytronP” manufactured by Stark Vitec Co., Ltd. ) And the like, and fluorenes such as 2,2 ′, 7,7′-tetrakis- (N, N-di-p-methoxyphenylamine) -9,9′-spirobifluorene (spiro-MeO-TAD) Derivatives, carbazole derivatives such as polyvinyl carbazole, triphenylamine derivatives, diphenylamine derivatives, polysilane derivatives, and polyaniline derivatives. Further, compound semiconductors having monovalent copper such as CuInSe ₂ and copper sulfide (CuS), gallium phosphide (GaP), nickel oxide (NiO), cobalt oxide (CoO), iron oxide (FeO), bismuth oxide ( Bi ₂ O ₃ ), molybdenum oxide (MoO ₂ ), and chromium oxide (Cr ₂ O ₃ ).

  Further, when the hole transport layer has a LUMO level shallower than the LUMO level of the material having a three-dimensional perovskite structure in the photoelectric conversion layer, to the transparent electrode side of the electrons generated in the photoelectric conversion layer Since the electronic block function which has the rectification effect which suppresses the movement of this is provided, it is preferable. Such a hole transport layer is also called an electron block layer. Among the materials constituting the electron blocking layer, examples of the low molecular organic compound include N, N′-bis (3-methylphenyl)-(1,1′-biphenyl) -4,4′-diamine (TPD). ) And 4,4′-bis [N- (naphthyl) -N-phenyl-amino] biphenyl (α-NPD), oxazole, oxadiazole, triazole, imidazole, imidazolone, stilbene derivatives, pyrazoline Derivative, tetrahydroimidazole, polyarylalkane, butadiene, 4,4 ′, 4 ″ tris (N- (3-methylphenyl) N-phenylamino) triphenylamine (m-MTDATA), porphyrin, tetraphenylporphyrin copper, phthalocyanine Porphyrins such as copper phthalocyanine and titanium phthalocyanine oxide Compounds, triazole derivatives, oxazizazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, and silazanes Examples of the polymer organic compound include polymers such as phenylene vinylene, fluorene, carbazole, indole, pyrene, pyrrole, picoline, thiophene, acetylene, and diacetylene, and derivatives thereof. Even if it is not an electron-donating compound, it can be used as long as it has a sufficient hole transporting property. Metal oxides such as Lucium, Chromium oxide, Chromium oxide, Manganese oxide, Cobalt oxide, Nickel oxide, Copper oxide, Gallium copper oxide, Strontium copper oxide, Niobium oxide, Molybdenum oxide, Indium copper oxide, Indium silver oxide and Iridium oxide , Selenium, tellurium, and antimony sulfide, which are used alone or in combination of two or more.

  The thickness of the hole transport layer is preferably 10 nm or more and 300 nm or less, more preferably 30 nm or more and 250 nm or less, and more preferably 50 nm or more and 200 nm from the viewpoint of suppressing dark current and preventing a decrease in photoelectric conversion efficiency. More preferably, it is as follows.

  As a method for forming the hole transport layer, a conventionally known method may be used, and any of a dry film formation method such as a vacuum deposition method and a wet film formation method such as a solution coating method may be used. A wet film forming method is preferable from the viewpoint of leveling the coated surface. Examples of the dry film forming method include a vapor deposition method such as a vacuum vapor deposition method and a sputtering method. The vapor deposition may be either physical vapor deposition (PVD) or chemical vapor deposition (CVD), but physical vapor deposition such as vacuum vapor deposition is preferred. Examples of the wet film forming method include an inkjet method, a spray method, a nozzle printing method, a spin coating method, a dip coating method, a casting method, a die coating method, a roll coating method, a bar coating method, and a gravure coating method.

(Electron transport layer)
The solid-state imaging device of this embodiment has an electron transport layer between the photoelectric conversion layer and the counter electrode so that charges (electrons) generated in the photoelectric conversion layer can be efficiently transported by the counter electrode. The electron transport layer is not particularly limited as long as it is known as an electron transport layer in a photoelectric conversion device such as a solid-state imaging device. For example, octaazaporphyrin and a p-type semiconductor perfluoro body (perfluoropentacene, Perfluorophthalocyanine, etc.), fullerenes, fullerene derivatives (eg, [6,6] -Phenyl-C61-Butyric Acid Methyl Ester; PCBM), organic compounds such as perylene, indenoindene and indenoindene derivatives, titanium oxide ( TiO _2, etc.), nickel oxide (NiO), tin oxide (SnO ₂ ), tungsten oxide (WO ₂ , WO ₃ , W ₂ O ₃ etc.), zinc oxide (ZnO), niobium oxide (Nb ₂ O ₅ etc.), tantalum oxide (Ta ₂ O _5, etc.), yttrium oxide (Y ₂ O _3, etc.),及Inorganic oxides such as strontium titanate (SrTiO _3, etc.). The electron transport layer may be porous or dense, and when laminating them, the porous electron transport layer and the dense electron transport layer are formed from the photoelectric conversion layer side. It is preferable that the layers are provided in order.

  Further, when the electron transport layer has a HOMO level deeper than the HOMO level of the material having a three-dimensional perovskite structure in the photoelectric conversion layer, the hole generated in the photoelectric conversion layer is directed to the counter electrode side. This is preferable because a hole blocking function having a rectifying effect to suppress the movement of the light is imparted. Such an electron transport layer is also called a hole blocking layer. Examples of the material constituting the hole blocking layer include oxadiazole derivatives such as 1,3-bis (4-tert-butylphenyl-1,3,4-oxadiazolyl) phenylene (OXD-7), anthraquinodi Methane derivatives, diphenylquinone derivatives, bathocuproine, bathophenanthroline, and derivatives thereof, triazole compounds, tris (8-hydroxyquinolinato) aluminum complexes, bis (4-methyl-8-quinolinato) aluminum complexes, silole compounds, porphyrins Compounds, styryl compounds such as DCM (4-dicyanomethylene-2-methyl-6- (4- (dimethylaminostyryl))-4Hpyran), naphthalenetetracarboxylic anhydride, naphthalenetetracarboxylic diimide, perylenetetracarboxylic Acid anhydride, Examples include n-type semiconductor materials such as rylene tetracarboxylic acid diimide, n-type inorganic oxides such as titanium oxide, zinc oxide, and gallium oxide, and alkali metal fluorides such as lithium fluoride, sodium fluoride, and cesium fluoride. . Further, an alkali metal compound doped with an organic semiconductor molecule is preferable because it has a function of improving electrical junction with the counter electrode. These are used singly or in combination of two or more.

  The thickness of the electron transport layer is preferably 10 nm or more and 300 nm or less, more preferably 30 nm or more and 250 nm or less, and more preferably 50 nm or more and 200 nm or less from the viewpoint of suppressing dark current and preventing a decrease in photoelectric conversion efficiency. Is more preferable.

  The method for forming the electron transport layer may be a conventionally known method, and may be any one of a dry film formation method such as a vacuum deposition method and a wet film formation method such as a solution coating method. However, from the viewpoint of leveling the coated surface, a wet film forming method is preferable. Examples of the dry film forming method include a vapor deposition method such as a vacuum vapor deposition method and a sputtering method. The vapor deposition may be either physical vapor deposition (PVD) or chemical vapor deposition (CVD), but physical vapor deposition such as vacuum vapor deposition is preferred. Examples of the wet film forming method include an inkjet method, a spray method, a nozzle printing method, a spin coating method, a dip coating method, a casting method, a die coating method, a roll coating method, a bar coating method, and a gravure coating method.

(Transparent electrode)
The transparent electrode is required to be sufficiently transparent with respect to the light to be detected because light enters the solid-state imaging device therefrom. Specific examples of materials used for the transparent electrode include tin oxide doped with antimony or fluorine (ATO, FTO), tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO). Transparent conductive metal oxides, 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, Examples thereof include organic conductive materials such as polyaniline, polythiophene and polypyrrole, and laminates of these with ITO. Among these, a transparent conductive metal oxide is preferable from the viewpoint of achieving both high conductivity and high transparency in a balanced manner.

  The thickness of the transparent electrode is not particularly limited, but is preferably 5 nm or more and 100 nm or less from the viewpoint of further suppressing leakage current, further preventing increase in resistance value, and further increasing transmittance. More preferably.

  The method for forming the transparent electrode is not particularly limited, and can be appropriately selected in consideration of suitability with the electrode material. Specific methods for forming the transparent electrode include wet methods such as a printing method and a coating method, physical methods such as a vacuum deposition method, a sputtering method and an ion plating method, and chemical methods such as a CVD method and a plasma CVD method. Can be mentioned. Further, when the electrode material is a transparent conductive metal oxide such as ITO, for example, an electron beam method, a sputtering method, a resistance heating vapor deposition method, a chemical reaction method (sol-gel method, etc.) is used. And a method of applying a dispersion of the metal oxide. Further, a transparent conductive metal oxide film such as ITO can be subjected to UV-ozone treatment and plasma treatment.

(Counter electrode)
The counter electrode may be transparent or may reflect light without being transparent. Specific examples of materials used for the counter electrode include tin oxide doped with antimony or fluorine (ATO, FTO), tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO). Transparent conductive metal oxides, 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 further Mixtures or laminates of metals and conductive metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, organic conductive materials such as polyaniline, polythiophene and polypyrrole, and these and ITO or titanium nitride The laminate of these is mentioned.

  Although the thickness of the counter electrode is not particularly limited, the viewpoint of obtaining a more uniform performance as a whole by sufficiently covering the layer serving as a base material when forming the counter electrode, and the counter electrode and the transparent electrode are From the viewpoint of preventing dark current from rising due to a local short circuit, it is preferably 5 nm or more and 30 nm or less.

  The method for forming the counter electrode is not particularly limited, and can be appropriately selected in consideration of suitability with the electrode material. As a method for forming the counter electrode, specifically, a wet method such as a printing method and a coating method, a physical method such as a vacuum deposition method, a sputtering method and an ion plating method, and a chemical method such as a CVD method and a plasma CVD method are used. Can be mentioned. Further, when the electrode material is a transparent conductive metal oxide such as ITO, for example, an electron beam method, a sputtering method, a resistance heating vapor deposition method, a chemical reaction method (sol-gel method, etc.) is used. And a method of applying a dispersion of the metal oxide. Further, a transparent conductive metal oxide film such as ITO can be subjected to UV-ozone treatment and plasma treatment.

  FIG. 2 is a schematic cross-sectional view partially showing another example of the solid-state imaging device of the present embodiment. A solid-state imaging device 200 illustrated in FIG. 2 includes a photoelectric conversion layer 210 including a material having a three-dimensional perovskite structure, and a hole transport layer 220 and an electron transport layer 230 stacked so as to sandwich the photoelectric conversion layer 210. The transparent electrode 240 and the counter electrode 250 are stacked so as to further sandwich them. The solid-state imaging device 200 further includes a color filter 260 on the transparent electrode 240 and a sealing layer 280 between the transparent electrode 240 and the color filter 260, and a protective layer on the color filter 260 and the sealing layer 280. 285 and microlenses 265 at positions corresponding to the color filters 260 on the protective layer 285. Further, the solid-state imaging device 200 includes an insulating layer 295 and a substrate 275 in this order below the counter electrode 250 and the electron transport layer 230, and includes a readout circuit 270 in the substrate 275, and the readout circuit 270 and the counter electrode 250 Are provided. Examples of the color filter 260 include a color filter 260b that transmits blue light, a color filter 260r that transmits red light, and a color filter 260g that transmits green light. The counter electrode 250 is provided below the color filters so as to correspond to the color filters 260b, 260r, and 260g.

Since the solid-state image sensor 200 shown in FIG. 2 includes the color filter 260 in addition to the operational effects of the solid-state image sensor 100 shown in FIG. 1, it is possible to more easily obtain images and videos of desired colors.
In addition, since the solid-state imaging device 200 includes the microlens 265, the solid-state imaging device 200 can collect light better. Furthermore, since the solid-state imaging device 200 includes the protective layer 285, the entire solid-state imaging device is protected and includes the insulating layer 295, so that a short circuit between the plurality of counter electrodes can be prevented. The color filter 260, the micro lens 265, the protective layer 285, and the insulating layer 295 are not particularly limited, and conventionally known ones can be used.

  As the photoelectric conversion layer 210, the hole transport layer 220, the electron transport layer 230, the transparent electrode 240, and the counter electrode 250, the photoelectric conversion layer 110, the hole transport layer 120, and the electron transport layer 130 in the solid-state imaging device 100 illustrated in FIG. Since the same electrode as the transparent electrode 140 and the counter electrode 150 can be used, detailed description is omitted here.

(Sealing layer)
The solid-state imaging device of this embodiment may further include a sealing layer. A material having a three-dimensional perovskite structure in the photoelectric conversion layer may be significantly deteriorated in performance due to the presence of deterioration factors such as water molecules and air. Therefore, in order to suppress the permeation of water molecules and the atmosphere, a sealing layer made of a material such as a dense metal oxide, a metal nitride and a metal nitride oxide such as ceramics and diamond-like carbon (DLC) is preferably used. By providing so that the whole photoelectric converting layer may be coat | covered, said deterioration can be prevented more effectively and reliably. The material of the sealing layer can be selected or formed according to the description in paragraphs [0210] to [0215] of Japanese Patent Application Laid-Open No. 2011-082508, for example.

(substrate)
The solid-state imaging device of the present embodiment may further include a substrate. The substrate is used for manufacturing a solid-state imaging device by stacking layers on the substrate, or used for increasing the mechanical strength of the solid-state imaging device. The kind in particular of board | substrate is not restrict | limited, For example, a semiconductor substrate, a glass substrate, and a plastic substrate are mentioned.

(Read circuit and connection part)
The reading circuit is provided for reading a signal corresponding to the charge generated in the photoelectric conversion layer. The readout circuit is composed of, for example, a CCD, a CMOS circuit, a TFT circuit, or the like, and is preferably shielded from light by a light shielding layer (not shown) disposed in the insulating layer. The readout circuit is electrically connected to the corresponding transparent electrode or counter electrode via a connection portion. The connecting portion is a plug or the like that is embedded in the insulating layer and electrically connects the transparent electrode or the counter electrode to the readout circuit. In the solid-state imaging device configured as described above, when light is incident, the light is incident on the photoelectric conversion layer, and charges are generated here. Electrons of the generated charges are collected by the counter electrode, and a voltage signal corresponding to the amount is output to the outside of the solid-state imaging device by the readout circuit.

  In the solid-state imaging device 200 shown in FIG. 2, since the readout circuit 270 and the like are provided on the side opposite to the light receiving surface side as compared with the conventional one using a silicon photodiode, the light receiving area can be widened. Further, since the thickness in the depth direction is not required, the incident angle of the light beam is not limited, and as a result, the light can be used efficiently and the pixels can be further miniaturized.

  FIG. 3 is a schematic cross-sectional view partially showing still another example of the solid-state imaging device of the present embodiment. A solid-state imaging device 300 illustrated in FIG. 3 includes a photoelectric conversion layer 310 including a material having a three-dimensional perovskite structure, a hole transport layer 320 and an electron transport layer 330 stacked so as to sandwich the photoelectric conversion layer, The transparent electrode 340 laminated | stacked on a positive hole transport layer, and the counter electrode 350 laminated | stacked on the lower side of an electron carrying layer are provided. The solid-state imaging device 300 further includes a color filter 360 on the transparent electrode 340, a sealing layer 380 between the transparent electrode 340 and the color filter 360, and a protective layer on the color filter 360 and the sealing layer 380. 385. Further, the solid-state imaging device 300 includes an insulating layer 395 and a substrate 375 in this order under the counter electrode 350 and the electron transport layer 330, and includes a readout circuit 370 in the substrate 375, and the readout circuit 370, the counter electrode 350, The connection part 390 which connects is provided. Examples of the color filter 360 include a color filter 360 b that transmits blue light, a color filter 360 r that transmits red light, and a color filter 360 g that transmits green light. The color filter 360 is a stack of layers in the solid-state imaging device 300. A plurality of two-dimensional arrays are arranged in a direction orthogonal to the direction. Further, since the counter electrode 350 is provided so as to correspond to each color filter 360, a plurality of the counter electrodes 350 are two-dimensionally arranged in a direction orthogonal to the stacking direction, similarly to the color filter 360. Further, a light shielding film 355 for blocking visible light is formed between the counter electrodes 350.

  The light shielding film 355 may be made of a black resist material such as an acrylic resin, or may be formed by laminating a plurality of materials having different refractive indexes, for example, a silicon oxide film and silicon A laminated structure of a nitride film and a laminated structure of a silicon oxide film and a titanium oxide film may be used.

  The solid-state imaging device 300 shown in FIG. 3 is more specifically configured by arranging a plurality of color filters 360 and counter electrodes 350 in a two-dimensional manner in addition to the operational effects of the solid-state imaging devices 100 and 200 shown in FIGS. Prepare in a matrix. Thereby, it acts as one photoelectric conversion element in a region where each color filter 360 and the counter electrode 350 exist, and the one photoelectric conversion element constitutes one pixel. Therefore, the solid-state image sensor 300 constitutes a plurality of pixels. As a result, in each photoelectric conversion element (pixel), an optical signal can be converted into an electric signal, and the electric signal can be sequentially output to the outside of the imaging element for each pixel.

  Although the solid-state imaging device of this embodiment has been described in detail above, the present invention is not limited to the above-described embodiment. The solid-state imaging device of the present invention may have a configuration that the conventional solid-state imaging device has in points other than the above as long as the achievement of the object of the present invention is not hindered. For example, in the above configuration, the lower electrode and the substrate are stacked via the insulating layer, and the connection portion is embedded in the insulating layer, and the readout circuit is embedded in the substrate. A substrate may be provided directly on the substrate, and both the connection portion and the readout circuit may be embedded in the substrate.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

Example 1
A solid-state imaging device having the same configuration as shown in FIG. 1 was produced as follows. First, a fluorine-doped tin oxide transparent conductive glass having a size of 25 mm × 25 mm (manufactured by Aldrich, product name “735159-EA”, hereinafter referred to as “FTO glass”) is used with a 2M hydrochloric acid aqueous solution and zinc powder. Etched. The FTO glass after etching was subjected to ultrasonic cleaning for 5 minutes in order of ethanol, acetone and isopropyl alcohol, dried by an air duster, and UV ozone cleaning for 5 minutes to obtain an FTO glass as a transparent electrode.

Further, a solution (0.4 M) obtained by further diluting 75% by mass of titanium diisopropoxide bis (acetylacetonate) in isopropyl alcohol (Aldrich) with butanol was applied to FTO glass by spin coating. Next, the FTO glass coated with the solution was heated on a hot plate at 130 ° C. for 5 minutes. The heated FTO glass was transferred to an electric furnace, further heated at 500 ° C. for 15 minutes, then taken out of the electric furnace and allowed to cool. The operation from the application to the cooling was repeated 4 times. Then, by immersing the substrate after cooling the TiCl ₄ aqueous solution prepared from the pure water 40mL and TiCl ₄ aqueous solution 1.5 mL, it was heated for 15 minutes at 70 ° C. in an oven. Thus, a laminate in which a layer made of titanium oxide as an electron transport layer was formed on the FTO glass was obtained. The laminate taken out from the oven was washed with pure water, dried by nitrogen blowing, and transferred to a glove box (under Ar gas atmosphere).

Next, 2.0 mL of dimethylformamide was added to a mixture of 490 mg of PbCl ₂ (manufactured by Wako Pure Chemical Industries, Ltd.) and 840 mg of methylammonium iodide, and heated to 100 ° C. to obtain a solution for spin coating. This solution was applied to the layer made of titanium oxide in the laminate in the glove box by spin coating, and chlorobenzene was dropped onto the substrate during the spin coating. The laminate after spin coating was heated on a hot plate at 100 ° C. for 2 hours. Thus, a laminate was obtained in which a layer made of MAPbI _{3 as} a photoelectric conversion layer was formed on a layer made of titanium oxide.

Next, 1 mL of chlorobenzene was added to 15 mg of poly-3-hexylthiophene (P3HT, manufactured by Aldrich) and heated to 100 ° C. to obtain a solution for spin coating. This solution was applied to the layer made of MAPbI ₃ in the laminate by spin coating. Thus, a laminate was obtained in which a layer made of poly-3-hexylthiophene, which is a hole transport layer, was formed on a layer made of MAPbI ₃ .

  Next, the laminated body was taken out from the glove box, and silver was deposited to 100 nm on the layer made of poly-3-hexylthiophene in the laminated body using a vapor deposition apparatus. In this way, a laminate in which a layer made of silver as a counter electrode was formed on a layer made of poly-3-hexylthiophene was obtained. Further, the laminate is put in a glove box, glass (soaked in isopropanol and ultrasonically cleaned, and further subjected to UV ozone cleaning) and a UV curable resin (product name “Moisture Cut WB90US-HV manufactured by Moresco”). ]) Was used to seal the laminate, and a solid-state imaging device was obtained.

  As a result of measuring the thickness of each layer in the solid-state imaging device obtained as described above by SEM observation, the thickness of the electron transport layer is 180 nm, the thickness of the photoelectric conversion layer is 400 nm, and the thickness of the hole transport layer is It was 170 nm.

(Comparative Example 1)
A product name “BS-520” (amorphous silicon) manufactured by SHARP was prepared as a conventional silicon photodiode.

(Evaluation of photoelectric conversion efficiency)
Under an environment of a temperature of 25 ° C., the solid-state imaging device was irradiated with sunlight under the conditions of spectral distribution: AM1.5 and irradiance: 1000 W / m ² to create an IV curve as output characteristics. . As a measuring device, a product name “OTENTO-SUN V” manufactured by Spectrometer Co., Ltd. is used as a solar simulator, and a product name “IV-2400” (source meter) which is an IV measuring system manufactured by Keithle is used as a measuring device. It was. Based on the IV curve, the photoelectric conversion efficiency was determined by the following formula. Relative evaluation when the photoelectric conversion efficiency in the solid-state image pickup device of Example 1 is set to 1 is “A” when exceeding 0.9, and “B” when exceeding 0.8 and 0.9 or less. , 0.7 and 0.8 or less were evaluated as “C”, and 0.7 or less were evaluated as “D.” As a result, the photoelectric conversion efficiency of the solid-state imaging device of Comparative Example 1 was evaluated. Was B.
η = P _max ÷ (E × A) × 100
Here, η is the photoelectric conversion efficiency (%), P _max is the output (W) at the optimum operating point, E is the irradiance (W / m ² ), and A is the light receiving area (m ² ).

(Evaluation of quantum efficiency)
The quantum efficiency expressed as a ratio (%) of how many electrons are generated with respect to photons absorbed per second by the photoelectric conversion layer in the solid-state imaging device was measured. The product name “CEP-2000MLQR”, which is a spectral sensitivity measuring device manufactured by Spectrometer Co., Ltd., was used as the measuring device. The quantum efficiency was determined at a blue wavelength (near 460 nm), a green wavelength (near 520 nm), and a red wavelength (near 680 nm). Relative evaluation when the quantum efficiency of the solid-state imaging device of Example 1 is set to 1 is “A” when 0.9 or more, “B” when 0.8 or more and less than 0.9, The case of 7 or more and less than 0.8 was evaluated as “C”, and the case of less than 0.7 was evaluated as “D.” As a result, the quantum efficiency of the solid-state imaging device of Comparative Example 1 was evaluated using the blue wavelength. B, B at the green wavelength, and D at the red wavelength.

(Measurement of light absorption coefficient)
About the photoelectric converting layer in a solid-state image sensor, the light absorption coefficient at the time of absorbing the light of a blue wavelength (near 460 nm), a green wavelength (near 520 nm), and a red wavelength (near 680 nm) was calculated | required. As the measuring apparatus, a product name “SolidSpec-3700” manufactured by Shimadzu Corporation, which is a UV-Vis-NIR measuring apparatus, was used. The light absorption coefficient in the solid-state imaging device of Example 1 was high at any of blue, green, and red wavelengths.

(Evaluation of light response speed)
Responsiveness of the photoelectric conversion layer in the solid-state imaging device was confirmed. The photoelectric conversion layer is irradiated with laser light with a pulse period (wavelength 639 nm, intensity is 10 mW and 30 mW), the photocurrent at that time is measured with an oscilloscope, and the rise time from 10% to 90% signal intensity is measured. Asked. When the rise time of the solid-state imaging device of Example 1 is 1, the relative value is less than 1.5, “A”, 1.5 to 2.0 but “B”, 2.0 and 3 Less than 0.0 was designated as “C” and 3.0 or more was designated as “D”. As a result, regarding the solid-state imaging device of Comparative Example 1, the evaluation of responsiveness was A at a laser beam intensity of 10 mW and C at a laser beam intensity of 30 mW.

  The solid-state imaging device of the present invention has high quantum efficiency, good light absorption, and high light response speed in a wide range of light intensity. Therefore, the solid-state imaging device of the present invention has industrial applicability in fields where these characteristics are required. Specifically, digital still cameras, digital video cameras, mobile phone cameras, medical cameras such as endoscope cameras, in-vehicle cameras, cameras for mobile devices other than the above, game console cameras, and industrial cameras As an image sensor in a facsimile, a scanner, a copier, and the like;

  100, 200, 300 ... solid-state imaging device, 110, 210, 310 ... photoelectric conversion layer, 120, 220, 320 ... hole transport layer, 130, 230, 330 ... electron transport layer, 140, 240, 340 ... transparent electrode, 150, 250, 350 ... counter electrode.

Claims (4)

A photoelectric conversion layer for photoelectrically converting incident light;
A hole transport layer for transporting holes to the photoelectric conversion layer;
An electron transport layer for transporting electrons to the photoelectric conversion layer;
A solid-state imaging device including a photoelectric conversion element including a pair of electrodes,
The photoelectric conversion layer, the hole transport layer, and the electron transport layer are laminated between the pair of electrodes,
The photoelectric conversion layer includes a material having a three-dimensional perovskite structure,
Solid-state image sensor.   The solid-state imaging device according to claim 1, wherein a plurality of pixels are configured by arranging a plurality of two-dimensionally at least one of the pair of electrodes.   3. The solid-state imaging device according to claim 1, wherein a plurality of pixels are formed by arranging one of the pair of electrodes in a two-dimensional manner with respect to a single layer of the photoelectric conversion layer.   The solid-state image sensor as described in any one of Claims 1-3 provided with a color filter on one electrode among a pair of said electrodes.