WO2012160911A1

WO2012160911A1 - Organic photoelectric conversion element

Info

Publication number: WO2012160911A1
Application number: PCT/JP2012/060475
Authority: WO
Inventors: 亮釜井; 関口　隆史
Original assignee: パナソニック株式会社
Priority date: 2011-05-24
Filing date: 2012-04-18
Publication date: 2012-11-29
Also published as: JP2014150081A

Abstract

Provided is an organic photoelectric conversion element which is provided with an electron extraction layer and which has high photoelectric conversion efficiency. This organic photoelectric conversion element is provided with a first electrode (2), a second electrode (6), a generation layer (4) arranged between the first electrode (2) and the second electrode (6), and an electron extraction layer (3) arranged between the generation layer (4) and the first electrode (2). The electron extraction layer (3) includes an n-type semiconductor, and the thickness of the electron extraction layer (3) is 0.1-15 nm.

Description

Organic power generation element

The present invention relates to an organic power generation element.

In recent years, the amount of energy used has increased dramatically with the development of industry. Therefore, the development of economical and high-performance new clean energy production technology that does not burden the global environment is required. In particular, solar cells are attracting attention as a new energy source because they use sunlight, which can be said to be infinite.

Most of the solar cells currently in practical use are inorganic solar cells using single crystal silicon, polycrystalline silicon, amorphous silicon, or the like. However, these inorganic silicon solar cells have the disadvantages that the manufacturing process is complicated and expensive, so that they have not been widely used in general households. In order to eliminate the disadvantages of such inorganic solar cells, research on organic power generation elements using organic materials that can be reduced in cost and increased in area with a simple process has become active.

The organic power generation element includes a power generation layer composed of a cathode, an anode, and an organic material interposed between the cathode and the anode. Furthermore, in order to efficiently extract electrons from the cathode to the outside, it has also been proposed to interpose an electron extraction layer between the power generation layer and the cathode. For example, in Japanese Patent Publication No. 2009-206470, in a photoelectric conversion element having at least a fullerene derivative of an electron acceptor and an electron donor compound between a pair of electrodes, bathocuproin (BCP) or It is disclosed to form an electron extraction layer composed of bathophenanthrene (Bphen) and a layer doped with alkali metal or alkali metal earth.

However, since the electron extraction layer becomes a resistance component in the organic power generation element, it can be a factor of reducing the photoelectric conversion efficiency of the organic power generation element.

The present invention has been made in view of the above points, and an object thereof is to provide an organic power generation element having an electron extraction layer and high photoelectric conversion efficiency.

The first organic power generation element according to the present invention includes a first electrode, a second electrode, a power generation layer disposed between the first electrode and the second electrode, and the power generation layer and the first An electron extraction layer disposed between the electrode and the first electrode; the electron extraction layer includes an n-type semiconductor; and the thickness of the electron extraction layer is in a range of 0.1 nm to 15 nm.

In the present invention, it is preferable that the electron extraction layer has a thickness of 10 nm or less.

In the present invention, the thickness of the electron extraction layer is preferably 0.5 nm or more.

In the present invention, the electron extraction layer includes at least one selected from zinc oxide, titanium oxide, cadmium sulfide, indium sulfide, cadmium selenide, indium selenide, zinc sulfide, and zinc selenide as an n-type semiconductor. preferable.

In the present invention, the electron extraction layer is preferably disposed so as to be in contact with the power generation layer, and the arithmetic average roughness Ra of the surface of the electron extraction layer on the power generation layer side is preferably 3 nm or less.

In the present invention, it is preferable that the arithmetic average roughness Ra of the surface on the power generation layer side of the electron extraction layer is 1.5 nm or less.

In the present invention, it is preferable that the arithmetic average roughness Ra of the surface of the electron extraction layer on the power generation layer side is 1 nm or less.

The second organic power generation element according to the present invention includes a second electrode, a first electrode, a power generation layer disposed between the second electrode and the first electrode, and the power generation layer and the first An electron extraction layer disposed so as to be in contact with the power generation layer between one electrode, and an arithmetic average roughness (surface roughness) Ra of the surface of the electron extraction layer on the power generation layer side is 3 nm or less .

According to the present invention, an organic power generation element having an electron extraction layer and high photoelectric conversion efficiency can be obtained.

Preferred embodiments of the invention are described in further detail. Other features and advantages of the present invention will be better understood with reference to the following detailed description and accompanying drawings.
It is sectional drawing which shows the outline of one Embodiment of this invention.

FIG. 1 shows the configuration of the organic power generation element according to this embodiment. The organic power generation element includes a base material 1, a first electrode 2, an electron extraction layer 3, a power generation layer 4, a hole extraction layer 5, a second electrode 6, and a surface protective layer 7. Laminated in order.

In the present embodiment, the second electrode 6 is a transparent electrode having optical transparency. The surface protective layer 7 is made of a light transmissive substance. Therefore, extraneous light incident from the second electrode 6 side of the organic power generation element passes through the surface protective layer 7 and the second electrode 6 and reaches the power generation layer 4.

The configuration of the organic power generation element according to the present invention is not limited to this embodiment. For example, the second electrode 6, the hole extraction layer 5, the power generation layer 4, the electron extraction layer 3, One electrode 2 and the surface protective layer 7 may have a structure in which these layers are stacked in this order (a stacked structure in the reverse order to the present embodiment). Further, the organic power generation element may not include the hole extraction layer 5. Further, the surface protective layer 7 is a layer formed as necessary in order to prevent deterioration of the organic power generation element, and the organic power generation element may not include the surface protection layer 7.

In the present embodiment, the material of the base material 1 is not particularly limited as long as elements of the organic power generation element such as an electrode and a power generation layer can be supported by the base material 1, but for example, transparent such as soda lime glass and non-alkali glass Glass; Examples thereof include resin materials such as polyester resin, polyolefin resin, polyamide resin, epoxy resin, and fluorine resin. Although it does not restrict | limit especially as a shape of the base material 1, A plate shape, a sheet form, etc. are mentioned. It is preferable that the surface of the substrate 1 on the power generation layer 4 side has high smoothness. In particular, the arithmetic average roughness Ra of this surface is preferably 3 nm or less, and more preferably 1 nm or less.

In the present embodiment, the first electrode 2 functions as a cathode during power generation by the organic power generation element. The cathode is an electrode for collecting electrons generated in the power generation layer 4. The material of the first electrode 2 is not particularly limited as long as it has electrical conductivity, and examples thereof include metals, alloys, electrically conductive compounds, and mixtures of two or more of these having a low work function. The work function of the material of the first electrode 2 is particularly preferably 5 eV or less. Examples of the material of the first electrode 2 include alkali metals, alkali metal halides, alkali metal oxides, alkaline earth metals, rare earths, and alloys and mixtures containing the above materials, such as sodium, Examples include sodium-potassium alloy, lithium, magnesium, magnesium-silver mixture, magnesium-indium mixture, aluminum-lithium alloy, Al / LiF mixture, and the like. As the material of the first electrode 2, aluminum, an Al / Al ₂ O ₃ mixture, or the like can also be used. As the material of the first electrode 2, a conductive material obtained by doping tin oxide or zinc oxide can also be used. Specific examples of the conductive material include indium-tin oxide (ITO), fluorine-doped Tin oxide (FTO), antimony doped tin oxide (ATO), phosphorus doped tin oxide (PTO), niobium doped tin oxide (NbTO), tantalum doped tin oxide (TaTO), aluminum doped zinc oxide (AZO), gallium doped zinc oxide (GZO) ), Indium-doped zinc oxide (IZO), and the like.

The first electrode 2 may be composed of a plurality of layers. For example, the first electrode 2 may have a laminated structure of alkali metal / Al, alkali metal halide / alkaline earth metal / Al, Al ₂ O ₃ / Al, or the like.

The first electrode 2 is formed, for example, by depositing the material as described above by a method such as a vacuum deposition method or a sputtering method.

In the present embodiment, the electron extraction layer 3 is interposed between the first electrode 2 and the power generation layer 4. In the present embodiment, the electron extraction layer 3 is in contact with the first electrode 2. In the present embodiment, the electron extraction layer 3 is also in contact with the power generation layer 4. The electron extraction layer 3 is preferably formed from a material that can improve the mobility of electrons from the power generation layer 4 to the first electrode 2. Moreover, it is preferable that the electron extraction layer 3 is formed of a material having a characteristic that inhibits the movement of holes. The electron extraction layer 3 is preferably formed from a material excellent in thin film forming ability.

The material for forming the electron extraction layer 3 is particularly preferably an n-type semiconductor material (a material that exhibits the characteristics of an n-type semiconductor when crystallized). That is, the electron extraction layer 3 is preferably made of an n-type semiconductor layer. In particular, the material of the electron extraction layer 3 is at least one selected from zinc oxide, titanium oxide, cadmium sulfide, indium sulfide, cadmium selenide, indium selenide, zinc sulfide, and zinc selenide, which are n-type semiconductor materials. Is preferred. These n-type semiconductors all have good light transmittance in a wide wavelength range in the visible light range. For this reason, when the power generation layer 4 is formed of a material having high visible light absorptivity and the base material 1 and the first electrode 2 are light transmissive, extraneous light is generated from the base material 1 side by organic power generation. It is also possible to cause photoelectric conversion by entering the element. Moreover, when the base material 1 and the 1st electrode 2 have a light transmittance, when external light injects from the 2nd electrode 6 side, it is preferable that the base material 1 is provided with a light reflection board. In this case, light that is transmitted through the first electrode 2 and the base material 1 without being absorbed by the power generation layer 4 reaches the power generation layer 4 again by being reflected by the light reflection plate, and is thereby absorbed. The amount of light absorption at 4 increases and the photoelectric conversion efficiency improves. Examples of such a light reflecting plate include a metal plate and a white resin, but the material is not particularly limited as long as the material has a function of reflecting light having a wavelength absorbed by the material constituting the power generation layer 4. Is not to be done.

In the present embodiment, the thickness of the electron extraction layer 3 is 0.1 nm or more and 15 nm or less, and the arithmetic average roughness Ra of the surface of the electron extraction layer 3 on the power generation layer 4 side is 3 nm or less. At least one of the conditions is met. Thereby, the photoelectric conversion efficiency of an organic power generation element improves. In particular, the thickness of the electron extraction layer 3 is preferably 0.1 nm or more and 15 nm or less, and the arithmetic mean roughness Ra of the surface of the electron extraction layer 3 on the power generation layer 4 side is preferably 3 nm or less. More preferably, the thickness of the electron extraction layer 3 is larger than 0.5 nm and smaller than 15 nm, and the arithmetic average roughness Ra of the surface of the electron extraction layer 3 on the power generation layer 4 side is 1 nm or less.

As described above, the thickness of the electron extraction layer 3 is preferably 0.1 nm or more and 15 nm or less. If the thickness of the electron extraction layer 3 is 0.1 nm or more, the function of the electron extraction layer 3 is sufficiently exhibited. The thickness of the electron extraction layer 3 is more preferably 0.5 nm or more, and further preferably 1 nm or more. Moreover, if this thickness is 15 nm or less, the electric resistance value of the electron extraction layer 3 is suppressed, so that the electric resistance of the electron extraction layer 3 can be almost ignored in the organic power generation element. In this case, the loss of the fill factor of the organic power generation element due to the series resistance by the electron extraction layer 3 is eliminated (the curve factor of the organic power generation element decreases due to the electrical resistance of the electron extraction layer 3). Can be prevented), and the photoelectric conversion efficiency of the organic power generation element is improved. The thickness of the electron extraction layer 3 is more preferably 10 nm or less.

The arithmetic average roughness Ra of the surface on the power generation layer 4 side of the electron extraction layer 3 is preferably as small as possible, and is preferably 3 nm or less as described above. The arithmetic average roughness Ra of the surface of the electron extraction layer 3 on the power generation layer 4 side is more preferably 1.5 nm or less, more preferably 1 nm or less, and further preferably 0.6 nm or less. Thus, the smaller the arithmetic average roughness Ra of the electron extraction layer 3 is, the higher the adhesion between the electron extraction layer 3 and the power generation layer 4 is, so that the interface resistance is reduced and the short circuit current density of the organic power generation element is reduced. (Jsc) increases. Thereby, the photoelectric conversion efficiency of an organic power generation element improves.

As a method for forming the electron extraction layer 3, there are a vacuum deposition method, a sputtering method, a chemical vapor deposition (CVD) method, a chemical deposition (CBD) method, an electrolytic deposition method, a sol-gel method, a spray pyrolysis method, and the like. Can be mentioned. In particular, when the electron extraction layer 3 is formed by depositing an n-type semiconductor by an evaporation method such as a vacuum evaporation method, a sputtering method, or a chemical vapor deposition (CVD) method, the thickness of the electron extraction layer 3 is controlled and smoothed. It becomes easy. For this reason, the electron extraction layer 3 that satisfies at least one of the conditions in which the thickness is 0.1 nm or more and 15 nm or less and the arithmetic average roughness Ra of the surface on the power generation layer 4 side is 3 nm or less can be formed. .

The power generation layer 4 includes an electron donating material (electron donating semiconductor) made of an organic compound and an electron accepting material (electron accepting semiconductor) made of an organic compound. In the present embodiment, the organic compound that is the material of the power generation layer 4 is preferably solvent-soluble.

Among the organic compounds that are the materials for the power generation layer 4, the electron-donating semiconductor is not particularly limited, but includes phthalocyanine pigments, indigo, thioindigo pigments, quinacridone pigments, merocyanine compounds, cyanine compounds, squalium compounds, polycyclic aromatics. Group compounds and the like. Also included are charge transfer agents, electroconductive organic charge transfer complexes, and conductive polymers used in organic electrophotographic photoreceptors. Although it does not specifically limit as a phthalocyanine pigment, The phthalocyanine which has bivalent center metals, such as Cu, Zn, Co, Ni, Pb, Pt, Fe, and Mg; Metal free phthalocyanine; Aluminum chlorophthalocyanine, Indium chlorophthalocyanine, Gallium Examples include trivalent metal phthalocyanines coordinated with halogen atoms such as chlorophthalocyanine; and other phthalocyanines coordinated with oxygen such as baanadyl phthalocyanine and titanyl phthalocyanine. Although it does not specifically limit as a polycyclic aromatic compound, Anthracene, tetracene, pentacene, those derivatives, etc. are mentioned. Although it does not specifically limit as a charge transfer agent, A hydrazone compound, a pyrazoline compound, a triphenylmethane compound, a triphenylamine compound, etc. are mentioned. The electroconductive organic charge transfer complex is not particularly limited, and examples thereof include tetrathiofulvalene and tetraphenyltetrathioflavalene. The conductive polymer that donates electrons is not particularly limited, but may be used in an organic solvent such as poly (3-alkylthiophene), polyparaphenylene vinylene derivatives, polyfluorene derivatives, thiophene polymers, and conductive polymer oligomers. A soluble thing is mentioned.

Among the organic compounds that are the materials of the power generation layer 4, the electron-accepting semiconductor is not particularly limited, but fullerene derivatives, carbon nanotubes, polyphenylene vinylenes, polyfluorenes, derivatives thereof, copolymers thereof, CN groups or CFs Examples include polymers containing _three groups.

When the power generation layer 4 is formed, for example, an organic compound that is a material of the power generation layer 4 is dissolved in a solvent to prepare a solution, and this solution is applied on the electron extraction layer 3 and formed into a film. Layer 4 is formed. The solvent is not particularly limited, but 1,2-dichlorobenzene, 1,2,4-trichlorobenzene, chlorobenzene, chloroform, xylene, toluene, 1-chloronaphthalene, acetone, isopropyl alcohol, ethanol, methanol, cyclohexane, etc. An organic solvent is mentioned. As the solvent, a main solvent and an additive solvent having different vapor pressures may be used. For example, 1,2-dichlorobenzene (vapor pressure: 160 Pa (20 ° C.)) may be used as the main solvent, and chloroform (vapor pressure: 21.2 kPa (20 ° C.)) may be used as the additive solvent. The combination of solvents is not limited to this. It is preferable that the main solvent and the added solvent have a difference of two or more orders of magnitude in vapor pressure, and that the volume ratio of all the solvents is in a relationship of main solvent> added solvent. Even if a plurality of types of solvents are used as the main solvent or a plurality of types of solvents are used as the additive solvent, there is no particular limitation as long as the relationship between the vapor pressure and the volume ratio of mixing is as described above.

The thickness of the power generation layer 4 is not particularly limited, but is preferably in the range of 80 to 240 nm.

When the power generation layer 4 is formed by a coating method, a method for applying a solution containing an organic compound that is a material of the power generation layer 4 is not particularly limited, but a spin coating method, a dip coating method, a die coating method, a gravure printing method. For example, a method in which the solution is brought into direct contact with the object, a method in which the solution is sprayed into the gas phase toward the object, such as an ink jet method or a spray coating method.

In the present embodiment, the hole extraction layer 5 is formed of a material that has the ability to transport holes and can improve the mobility of holes from the hole extraction layer 5 to the second electrode 6. Is preferred. The hole extraction layer 5 is preferably formed from a material that inhibits electron movement. The hole extraction layer 5 is preferably formed from a material having excellent thin film forming ability.

The material for forming the hole extraction layer 5 is not particularly limited, but phthalocyanine derivatives, naphthalocyanine derivatives, porphyrin derivatives, N, N′-bis (3-methylphenyl)-(1,1′-biphenyl) Aromatic diamine compounds such as -4,4'-diamine (TPD) and 4,4'-bis [N- (naphthyl) -N-phenyl-amino] biphenyl (α-NPD), oxazole, oxadiazole, triazole Imidazole, imidazolone, stilbene derivative, pyrazoline derivative, tetrahydroimidazole, polyarylalkane, butadiene, 4,4 ′, 4 ″ -tris (N- (3-methylphenyl) N-phenylamino) triphenylamine (m-MTDATA ), And polyvinylcarbazole, polysilane, aminopyridy Examples thereof include polymer materials such as conductive polymers such as derivatives, polyethylene dioxide thiophene (PEDOT), sulfonated polythiophene, etc. In addition, even if it is an inorganic material, if it has hole transportability, hole extraction layer 5 Such inorganic materials are not particularly limited, but include inorganic oxides such as molybdenum trioxide, vanadium pentoxide, tungsten trioxide, and rhenium oxide that have the ability to transport holes. And inorganic oxides such as nickel oxide and copper oxide which are p-type semiconductors.

The method for forming the hole extraction layer 5 is not particularly limited, but when the material for forming the hole extraction layer 5 is an inorganic material or a low molecular material, a vacuum deposition method, a sputtering method, or the like can be given. When the material for forming the hole extraction layer 5 is a polymer material, a coating method such as a spin coating method, a dip coating method, a die coating method, or a gravure printing method can be used.

The thickness of the hole extraction layer 5 is not particularly limited, but in order to reduce the series resistance of the organic power generation element, it is preferably 200 nm or less when formed from an inorganic material, and is formed from an organic material. In some cases, it is preferably 20 nm or less.

In the present embodiment, when the organic power generation element exhibits a high photoelectric conversion function without the hole extraction layer 5, the organic power generation element may not include the hole extraction layer 5.

In the present embodiment, the second electrode 6 functions as an anode during power generation by the organic power generation element. The anode is an electrode for collecting holes generated in the power generation layer 4. The material for forming the second electrode 6 is not particularly limited as long as it has conductivity, but a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function is preferable. In particular, the work function of the material for forming the second electrode 6 is preferably 4 eV or more. The material of the second electrode 6 is not particularly limited, but is a metal such as gold; CuI, ITO (indium-tin oxide), SnO ₂ , ZnO, IZO (indium-zinc oxide), etc .; PEDOT And a conductive polymer such as polyaniline; a conductive polymer doped with an arbitrary acceptor; and a material having both conductivity and light transmittance, such as a carbon nanotube. The work function of the second electrode 6 is preferably larger than the work function of the first electrode 2.

The second electrode 6 is formed, for example, on the hole extraction layer 5 or on the power generation layer 4 when the hole extraction layer 5 is unnecessary by a method such as vacuum deposition, sputtering, or coating. When extraneous light passes through the second electrode 6 and enters the power generation layer 4, the light transmittance of the second electrode 6 is preferably 70% or more. However, the case where extraneous light passes through the first electrode 2 and enters the power generation layer 4 is not limited thereto. The sheet resistance of the second electrode 6 is preferably several hundred Ω / □ or less, more preferably 100Ω / □ or less. The film thickness of the second electrode 6 varies depending on the material in order to control the light transmittance, sheet resistance, and other characteristics of the second electrode 6 as described above, but is preferably 500 nm or less. A range of 10 to 200 nm is more preferable.

From the viewpoint of reducing the cost of the organic power generation element, the hole extraction layer 5 and the second electrode 6 are preferably formed by a coating method. Regarding the solvent used in the coating method, it is preferable that the power generation layer 4 is not dissolved and the wettability to the power generation layer 4 is good. The solvent is not particularly limited, and examples thereof include water, ethanol, 2-propanol and the like. In order to improve the wettability with respect to the power generation layer 4, a surfactant may be added to the solvent. The addition amount of the surfactant to the solvent is preferably in the range of 0.01% to 5% by volume ratio.

In the present embodiment, the surface protective layer 7 may be formed on the second electrode 6. As shown in FIG. 1, the surface protective layer 7 includes a first electrode 2, an electron extraction layer 3, a power generation layer 4, a hole extraction layer 5, and a second electrode 6 laminated on the substrate 1. You may form so that all may be covered. The surface protective layer 7 is provided to protect the electrode, the power generation layer, and the like from the outside.

The surface protective layer 7 preferably has a gas barrier property. The surface protective layer 7 is preferably light transmissive. The surface protective layer 7 is preferably a film-like or plate-like structure. The light transmittance of the surface protective layer 7 is preferably as high as possible, but it is particularly preferable that this light transmittance is 70% or more. Such a surface protective layer 7 is not particularly limited, but for example, vapor deposition of inorganic oxides such as zinc oxide, titanium dioxide, cerium oxide, zirconium oxide on a film such as polyethylene terephthalate, polyester, polycarbonate, etc. in order to enhance gas barrier properties. It can be configured by forming a thin film layer.

Between the second electrode 6 and the surface protective layer 7, an adhesive layer for adhering both may be interposed. The adhesive layer is not particularly limited, but is preferably formed from a material that does not cause deterioration of the second electrode 6 and the surface protective layer 7. Moreover, it is preferable that the light transmittance of the laminated body of the surface protective layer 7 and the adhesive layer is 70% or more. The material for such an adhesive layer is not particularly limited as long as it has adhesiveness, but a thermosetting resin, a thermoplastic resin, an ultraviolet curable resin, or the like can be used. Preferable specific examples of the material of such an adhesive layer include ethylene-vinyl acetate copolymer resin, modified polyethylene resin, polyvinyl butyral resin, ethylene / acrylic acid ester copolymer resin, and the like.

Of course, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

[Example 1]
A first electrode (cathode) having a thickness of 80 nm was formed by depositing Al on the glass substrate by vacuum deposition. An electron extraction layer having a thickness of 8 nm was formed on this first electrode by depositing titanium dioxide (TiO ₂ ) by sputtering.

When the arithmetic average roughness of the surface of the electron extraction layer was measured with AFM (manufactured by Shimadzu Corporation, model number SFT-3500), the arithmetic average roughness Ra obtained by measuring the range of 10 μm square was 0.8. It was 5 nm.

Poly (3-hexylthiophene) (abbreviated as P3HT; manufactured by Merck, regioregular type) as an electron-donating material, and [6,6] -phenyl C61 butyric acid methyl ester (abbreviated as PCBM) which is a fullerene derivative as an electron-accepting material; Solenne) was prepared. 1,2-dichlorobenzene (vapor pressure: 160 Pa (20 ° C.)) was prepared as the main solvent, and chloroform (vapor pressure; 21.2 kPa (20 ° C.)) was prepared as the additive solvent. 1,2-dichlorobenzene and chloroform were mixed at a volume ratio of 6: 4 to prepare a mixed solvent, and a material in which P3HT and PCBM were mixed in the mixed solvent at a mass ratio of 1: 0.7 was mixed with a solid content. A mixed solution was prepared by dissolving to a concentration of 51 mg / mL.

A power generation layer having a thickness of 200 nm was formed by applying the mixed solution on the electron extraction layer by a spin coating method in a glove box having a dew point of -76 ° C. or lower and oxygen of 1 ppm or lower in a dry nitrogen atmosphere.

The laminate including the glass substrate, the first electrode, the electron extraction layer, and the power generation layer obtained so far is placed in a glove box in a dry nitrogen atmosphere with a dew point of −76 ° C. or less without being exposed to the atmosphere. Annealing treatment was performed by heating at 110 ° C. for 10 minutes.

Next, a Plexcore OC1200 solution (manufactured by Plextronics) was applied on the power generation layer by a spin coating method to form a hole extraction layer having a thickness of 50 nm.

Next, PEDOT / PSS (CLEVIOS F ET) was mixed with isopropanol at a volume ratio of 50% and surfactant Tergitol 15-S-9 (manufactured by Dow Chemical Co.) at a volume ratio of 0.05%. Thus, a solution was prepared, and this solution was applied onto the hole extraction layer by a spin coating method, thereby forming a second electrode (anode) having a thickness of 100 nm.

After sufficiently drying the laminate comprising the glass substrate, the first electrode, the electron extraction layer, the power generation layer, the hole extraction layer, and the second electrode obtained so far under a nitrogen flow, in a nitrogen atmosphere Annealing treatment was performed by heating at 130 ° C. for 5 minutes. Subsequently, the laminate was transported into a glove box having a dry nitrogen atmosphere with a dew point of −76 ° C. or lower.

A glass sealing plate was prepared. A sealing material made of an ultraviolet curable resin was bonded to the outer peripheral portion of one surface of the sealing plate over the entire periphery. Further, a water absorbing material (getter) in which calcium oxide was kneaded was attached to the inside of the sealing material on the surface of the sealing plate on which the sealing material was bonded, with an adhesive. The sealing plate is transported into the glove box together with the laminate, and the surface on the side where the sealing material of the sealing plate is bonded is opposed to the second electrode of the laminate in the glove box. At the same time, a sealing material was stacked on the substrate. In this state, the sealing material was cured by irradiating the sealing material with ultraviolet rays. This formed the surface protection layer which consists of a sealing board.

Thereby, an organic power generation element having an element area of 0.10 cm ² was obtained.

[Example 2]
In Example 1, when the electron extraction layer was formed, titanium dioxide (TiO ₂ ) was formed on the first electrode to a thickness of 15 nm by a sputtering method. When the arithmetic average roughness of the surface of this electron extraction layer was measured by AFM, the arithmetic average roughness Ra obtained by measuring a range of 10 μm square was 0.6 nm.

Otherwise, the same method as in Example 1 was used to obtain an organic power generation element having an element area of 0.10 cm ² .

[Example 3]
In Example 1, when the electron extraction layer was formed, titanium dioxide (TiO ₂ ) was formed on the first electrode to a thickness of 0.5 nm by a sputtering method. When the arithmetic average roughness of the surface of this electron extraction layer was measured by AFM, the arithmetic average roughness Ra obtained by measuring the range of 10 μm square was 0.4 nm.

[Example 4]
In Example 1, when the power generation layer is formed, poly (2-methoxy-5- (3′-7′-dimethyloctyloxy) -1,4-phenylenevinylene) (MDMO-) is used as an electron donating material used in the power generation layer. Abbreviated as PPV; manufactured by Merck & Co., Inc.). A mixed solvent was prepared by mixing 2-dichlorobenzene with chloroform at a volume ratio of 6: 4, and a material in which MDMO-PPV and PCBM were mixed in the mixed solvent at a mass ratio of 1: 4 was mixed with a solid content concentration. Was dissolved so as to be 40 mg / mL to prepare a mixed solution.

This mixed solution was similarly applied by spin coating on the electron extraction layer in a glove box having a dew point of −76 ° C. or lower and oxygen of 1 ppm or lower on a dry nitrogen atmosphere to form a power generation layer having a thickness of 150 nm.

In this example, the electron extraction layer was formed by the same method as in Example 1. When the arithmetic average roughness of the surface of the electron extraction layer was measured by AFM, it was obtained by measuring a 10 μm square range. The obtained arithmetic average roughness Ra was 0.5 nm.

[Example 5]
In Example 4, when the electron extraction layer was formed, titanium dioxide (TiO ₂ ) was formed on the first electrode to a thickness of 15 nm by a sputtering method. When the arithmetic average roughness of the surface of this electron extraction layer was measured by AFM, the arithmetic average roughness Ra obtained by measuring a range of 10 μm square was 1.5 nm.

Otherwise, the same method as in Example 4 was used to obtain an organic power generation element having an element area of 0.10 cm ² .

[Example 6]
In Example 1, when the electron extraction layer was formed, a titanium dioxide nanoparticle dispersion (average particle size 3 nm; manufactured by TAYCA) was applied onto the first electrode by a spin coating method to form a coating film. The laminate including the glass substrate, the first electrode, and the coating film obtained so far was annealed by heating at 150 ° C. for 10 minutes in the air. Thereby, the 15-nm-thick electron extraction layer was formed because the coating film dried. When the arithmetic average roughness of the surface of this electron extraction layer was measured by AFM, the arithmetic average roughness Ra obtained by measuring a range of 10 μm square was 1.5 nm.

[Example 7]
In Example 1, when the electron extraction layer was formed, zinc oxide (ZnO) was formed to a thickness of 8 nm on the first electrode by a sputtering method. When the arithmetic average roughness of the surface of this electron extraction layer was measured by AFM, the arithmetic average roughness Ra obtained by measuring a range of 10 μm square was 0.5 nm.

[Example 8]
In Example 1, when the electron extraction layer was formed, cadmium sulfide (CdS) was formed to a thickness of 8 nm on the first electrode by sputtering. When the arithmetic average roughness of the surface of this electron extraction layer was measured by AFM, the arithmetic average roughness Ra obtained by measuring a range of 10 μm square was 0.5 nm.

[Example 9]
In Example 1, when the electron extraction layer was formed, indium sulfide (In ₂ S ₃ ) was formed on the first electrode to a thickness of 8 nm by a sputtering method. When the arithmetic average roughness of the surface of this electron extraction layer was measured by AFM, the arithmetic average roughness Ra obtained by measuring a range of 10 μm square was 0.5 nm.

[Example 10]
In Example 1, when the electron extraction layer was formed, selenium cadmium (CdSe) was formed to a thickness of 8 nm on the first electrode by a sputtering method. When the arithmetic average roughness of the surface of this electron extraction layer was measured by AFM, the arithmetic average roughness Ra obtained by measuring a range of 10 μm square was 0.5 nm.

[Example 11]
In Example 1, when the electron extraction layer was formed, indium selenide (In ₂ Se ₃ ) was formed to a thickness of 8 nm on the first electrode by a sputtering method. When the arithmetic average roughness of the surface of this electron extraction layer was measured by AFM, the arithmetic average roughness Ra obtained by measuring a range of 10 μm square was 0.5 nm.

[Example 12]
In Example 1, when the electron extraction layer was formed, zinc sulfide (ZnS) was formed to a thickness of 8 nm on the first electrode by a sputtering method. When the arithmetic average roughness of the surface of this electron extraction layer was measured by AFM, the arithmetic average roughness Ra obtained by measuring a range of 10 μm square was 0.5 nm.

[Example 13]
In Example 1, when the electron extraction layer was formed, zinc selenide (ZnSe) was formed to a thickness of 8 nm on the first electrode by a sputtering method. When the arithmetic average roughness of the surface of this electron extraction layer was measured by AFM, the arithmetic average roughness Ra obtained by measuring a range of 10 μm square was 0.5 nm.

[Comparative Example 1]
In Example 1, an organic power generation element having an element area of 0.10 cm ² was obtained in the same manner as in Example 1 except that no electron extraction layer was formed.

[Comparative Example 2]
In Example 1, when the electron extraction layer was formed, a titanium dioxide nanoparticle dispersion (average particle size 5 nm; manufactured by TAYCA) was applied onto the first electrode by a spin coating method to form a coating film. The laminate including the glass substrate, the first electrode, and the coating film obtained so far was annealed by heating at 150 ° C. for 10 minutes in the air. Thereby, the 15-nm-thick electron extraction layer was formed because the coating film dried. When the arithmetic average roughness of the surface of this electron extraction layer was measured by AFM, the arithmetic average roughness Ra obtained by measuring a range of 10 μm square was 3.2 nm.

[Evaluation]
Photoelectric conversion efficiencies of the organic power generation elements obtained in the above examples and comparative examples were measured under the conditions of irradiating simulated sunlight (AM1.5, 1 sun) with a solar simulator (manufactured by Yamashita Denso). The results are shown in Tables 1 to 3. Table 1 shows the results of Examples 1 to 5 and Comparative Example 1. Table 2 shows the results of Examples 1 to 3, Example 6, and Comparative Examples 1 and 2. Table 3 shows the results of Example 1 and Examples 7 to 13.

When the electron extraction layer was formed of titanium dioxide as in Examples 1 to 3 and the thickness thereof was 0.5 to 15 nm, a photoelectric conversion efficiency of 1.2% or more was obtained. Further, when the thickness of the electron extraction layer is 8 nm as in Example 1, the thickness of the electron extraction layer is 0 when the thickness of the electron extraction layer is 15 nm as in Example 2 or as in Example 3. The photoelectric conversion efficiency was better than in the case of 0.5 nm. That is, high photoelectric conversion efficiency was obtained when the thickness of the electron extraction layer was larger than 0.5 nm and smaller than 15 nm.

In Comparative Example 1 where no electron extraction layer was provided, the conversion efficiency was extremely reduced.

Even when the composition of the power generation layer is changed as in Example 4 and Example 5, when the electron extraction layer is formed of titanium dioxide and has a thickness of 8 nm as in Example 4, Example 5 Thus, the photoelectric conversion efficiency was better than when the thickness of the electron extraction layer was 15 nm.

Further, when the arithmetic average roughness Ra of the surface of the electron extraction layer is 3 nm or less as in Examples 1, 2, 3 and 6, the arithmetic average roughness of the surface of the electron extraction layer as in Comparative Example 2 is used. The photoelectric conversion efficiency was better than when Ra was larger than 3 nm. Further, when the arithmetic average roughness of the surface of the electron extraction layer is 1 nm or less as in Examples 1 to 3, the arithmetic average roughness Ra of the surface of the electron extraction layer is larger than 1 nm as in Example 6. The photoelectric conversion efficiency was better than the case. That is, as can be seen from the comparison of Example 2, Example 6, and Comparative Example 2, the smaller the value of the arithmetic average roughness Ra of the surface of the electron extraction layer, the better the photoelectric conversion efficiency.

In particular, as in Example 1, when the thickness of the electron extraction layer is larger than 0.5 nm and smaller than 15 nm, and the arithmetic average roughness Ra of the surface on the power generation layer side of the electron extraction layer is 1 nm or less, The highest photoelectric conversion efficiency was obtained.

Further, when the electron extraction layer was formed of various n-type semiconductors and had a thickness of 8 nm as in Examples 7 to 13, the photoelectric conversion efficiency was good. From this, even when the electron extraction layer was formed of an n-type semiconductor other than titanium dioxide, it was confirmed that the photoelectric conversion efficiency was good when the thickness was 15 nm or less (more specifically, 10 nm or less).

Claims

A first electrode; a second electrode; a power generation layer disposed between the first electrode and the second electrode; and an electron extraction disposed between the power generation layer and the first electrode An organic power generation element including a layer, wherein the electron extraction layer includes an n-type semiconductor, and the thickness of the electron extraction layer is in a range of 0.1 nm to 15 nm.
The organic power generation element according to claim 1, wherein the electron extraction layer has a thickness of 10 nm or less.
The organic power generation element according to claim 1, wherein the electron extraction layer has a thickness of 0.5 nm or more.
The electron extraction layer includes at least one selected from zinc oxide, titanium oxide, cadmium sulfide, indium sulfide, cadmium selenide, indium selenide, zinc sulfide, and zinc selenide as an n-type semiconductor. The organic power generation element as described in any one.
5. The electron extraction layer is disposed so as to be in contact with the power generation layer, and the arithmetic average roughness Ra of the surface of the electron extraction layer on the power generation layer side is 3 nm or less. Organic power generation element.
The organic power generation element according to claim 5, wherein an arithmetic average roughness Ra of a surface of the electron extraction layer on the power generation layer side is 1.5 nm or less.
The organic power generation element according to claim 6, wherein an arithmetic average roughness Ra of the surface on the power generation layer side of the electron extraction layer is 1 nm or less.
A second electrode; a first electrode; a power generation layer disposed between the second electrode and the first electrode; and the power generation layer in contact with the power generation layer and the first electrode. An organic power generation element comprising an electron extraction layer arranged as described above, wherein an arithmetic average roughness Ra of the surface of the electron extraction layer on the power generation layer side is 3 nm or less.
The organic power generation element according to claim 8, wherein an arithmetic average roughness Ra of a surface of the electron extraction layer on the power generation layer side is 1.5 nm or less.
The organic power generation element according to claim 9, wherein an arithmetic average roughness Ra of a surface of the electron extraction layer on the power generation layer side is 1 nm or less.
11. The electron extracting layer includes at least one selected from zinc oxide, titanium oxide, cadmium sulfide, indium sulfide, cadmium selenide, indium selenide, zinc sulfide, and zinc selenide as an n-type semiconductor. The organic power generation element as described in any one.