JP5774566B2 - Organic thin film solar cell - Google Patents

Description

  The present invention relates to an organic thin film solar cell, and more particularly to an organic thin film solar cell including an electron transport layer having at least two metal oxide layers formed from metal oxide particles having a predetermined average particle diameter.

In recent years, flexible electronic devices as soft matter have attracted attention. In particular, there is an increasing expectation for flexible organic electronic devices, particularly organic thin-film solar cells, that can be expected to be lightweight and cost-effective.
As a configuration of the organic thin film solar cell, an organic thin film having electron conductivity and / or hole conductivity is generally arranged between two different electrodes, at least one of which is transparent. Such an organic thin film solar cell is easy to manufacture as compared with an inorganic device using silicon or the like, and has an advantage that it can be manufactured at a low cost.

For example, Patent Document 1 discloses a photoelectric cell (organic thin-film solar battery) having a mesh electrode, and states that it has sufficient flexibility that can be manufactured by continuous roll-to-roll. .
In Patent Document 1, it is stated that LiF or a metal oxide is used for the electron transport layer.

JP 2006-521700 A

On the other hand, in recent years, for organic thin-film solar cells, it shows excellent photoelectric conversion efficiency even after being bent because it is used by pasting it on curved surfaces other than flat surfaces and complex shapes such as automobile bodies and building roofs. It is demanded.
When the present inventors measured the photoelectric conversion efficiency after a predetermined | prescribed bending test (bending test) using the organic thin-film solar cell which has an electron carrying layer containing the metal oxide described in patent document 1. The present inventors have found that the photoelectric conversion efficiency is greatly reduced as compared with that before the bending test.
In the first place, in the organic thin film solar cell described in Patent Document 1, the photoelectric conversion efficiency in a state before being bent does not reach the level required recently, and further improvement is necessary.

  In view of the above circumstances, an object of the present invention is to provide an organic thin-film solar cell that exhibits excellent photoelectric conversion performance before being subjected to bending treatment, and that suppresses deterioration of photoelectric conversion performance before and after the bending treatment. And

As a result of intensive studies on the problems of the prior art, the present inventors are related to an electron transport layer containing a metal oxide that is an inorganic substance as a main cause of deterioration in photoelectric conversion performance after a bending test. I found out. More specifically, when an organic thin-film solar cell is bent, a large stress is applied to the electron transport layer portion composed of a metal oxide that is an inorganic substance, causing cracks and peeling of the layer. I found out.
Based on this finding, the present inventors have found that the problem can be solved by the following configuration.

(1) On a plastic support, it has at least a negative electrode, an electron transport layer, a photoelectric conversion layer containing at least an organic material, a hole transport layer, and a positive electrode in this order, and the negative electrode is a metal pattern layer And a transparent conductive resin layer, wherein the electron transport layer is formed of a first metal oxide layer formed from metal oxide particles having an average particle diameter of 1 to 10 nm and metal oxide particles having an average particle diameter of 20 to 100 nm. An organic thin film solar cell comprising at least two layers with a second metal oxide layer.
(2) The organic thin-film solar cell according to (1), wherein the metal oxide particles include metal oxide particles having at least one metal atom selected from the group consisting of zinc, titanium, tin, and tungsten.
(3) The organic thin-film solar cell according to (1) or (2), wherein the first metal oxide layer has a thickness of 10 to 100 nm.
(4) The organic thin-film solar cell according to any one of (1) to (3), wherein the second metal oxide layer has a thickness of 10 to 200 nm.
(5) Furthermore, the organic thin-film solar cell in any one of (1)-(4) which has a gas barrier layer.

  ADVANTAGE OF THE INVENTION According to this invention, while performing the photoelectric conversion performance outstanding before performing a bending process, the organic thin film solar cell by which deterioration of the photoelectric conversion performance before and behind a bending process is suppressed can be provided.

It is a schematic sectional drawing which shows 1st Embodiment of the organic thin-film solar cell of this invention. It is an arrow top view along the AA line in FIG. It is a schematic plan view of other embodiment of the metal pattern layer in 1st Embodiment of the organic thin-film solar cell of this invention. It is a schematic sectional drawing which shows 2nd Embodiment of the organic thin-film solar cell of this invention.

Below, the suitable form of the organic thin-film solar cell of this invention is explained in full detail.
First, one of the features of the present invention compared to the prior art is that the electron transport layer has at least two layers formed of metal oxide particles having different average particle diameters. More specifically, the electron transport layer is a first metal oxide layer formed of metal oxide particles having an average particle diameter of 1 to 10 nm and a metal oxide particle having an average particle diameter of 20 to 100 nm. The point which has a 2 metal oxide layer is mentioned. When the electron transport layer has at least these two layers, the electron transport ability between the metal oxide particles is improved, and the photoelectric conversion efficiency is improved. Further, when the organic thin film solar cell is bent, the metal oxide particles having a small particle size in the first metal oxide layer are twisted in the second metal oxide layer in contact with the first metal oxide layer. By moving so as to enter between large metal oxide particles, the stress of deformation applied to the electron transport layer can be reduced. As a result, it is presumed that the occurrence of cracks in the electron transport layer and separation from other adjacent layers are suppressed.

[First Embodiment]
FIG. 1 is a cross-sectional view schematically showing the layer configuration of the first embodiment of the organic thin-film solar cell of the present invention. The organic thin film solar cell 10 includes a plastic support 12, a negative electrode 14, an electron transport layer 16, a photoelectric conversion layer 18, a hole transport layer 20, and a positive electrode 22 in this order. The negative electrode 14 has a metal pattern layer 24 and a transparent conductive resin layer 26. The electron transport layer 16 includes a first metal oxide layer 28 and a second metal oxide layer 30. The organic thin film solar cell 10 is a so-called reverse organic thin film solar cell, and the surface on the plastic support 12 side is the light receiving surface, and the electrode near the plastic support corresponds to the negative electrode. That is, light is irradiated from the plastic support 12 side, and the light reaches the photoelectric conversion layer 18 through the plastic support 12, the negative electrode 14, and the electron transport layer 16.
In the following, first, the electron transport layer 16 will be described in detail, and then other configurations (plastic support 12, negative electrode 14, photoelectric conversion layer 18, hole transport layer 20, positive electrode 22) will be described in detail.
In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value.

(Electron transport layer)
The electron transport layer 16 is a layer provided between the negative electrode 14 and the photoelectric conversion layer 18 so that electrons are easily transported from the photoelectric conversion layer 18 to the negative electrode 14. Note that the electron transport layer 16 also has a function of blocking the movement of holes from the photoelectric conversion layer 18 to the negative electrode 14.
The electron transport layer 16 has an adjacent first metal oxide layer 28 and second metal oxide layer 30 in this order on the negative electrode 14. Hereinafter, the first metal oxide layer 28 and the second metal oxide layer 30 will be described in detail.

The first metal oxide layer 28 is a layer formed from metal oxide particles having an average particle diameter of 1 to 10 nm (hereinafter also referred to as metal oxide particles A as appropriate). That is, the first metal oxide layer 28 is mainly composed of metal oxide particles, and is usually a so-called porous layer.
The kind of the metal oxide particle A used is not limited, for example, the metal oxide particle which has the property of an n-type semiconductor can be used conveniently. Examples thereof include metal oxide particles having at least one metal atom selected from the group consisting of zinc, titanium, tin, and tungsten. Among these, metal oxide particles having at least one metal atom selected from the group consisting of zinc and titanium are preferable in that the initial photoelectric conversion performance before bending is more excellent.

The average particle diameter of the metal oxide particles A is 1 to 10 nm. When the average particle diameter is within this range, the photoelectric conversion performance after the bending test is maintained. Especially, 2-8 nm is preferable and 3-6 nm is more preferable at the point which the photoelectric conversion performance after bending is more excellent.
The average particle diameter of the metal oxide particles A is measured by observing the cross section of the first metal oxide layer 28 with an electron microscope, measuring the diameter of at least 100 metal oxide particles, and calculating them. Find on average. In addition, when the metal oxide particle A is not spherical, the major axis is handled as the diameter. For simplicity, the diameter may be obtained from the surface irregularity period using an atomic force microscope (AFM).

  Although the layer thickness in particular of the 1st metal oxide layer 28 is not restrict | limited, 5-200 nm is preferable and 10-100 nm is more preferable at the point which the photoelectric conversion performance after a bending is more excellent.

The second metal oxide layer 30 is a layer formed from metal oxide particles having an average particle diameter of 20 to 100 nm (hereinafter also referred to as metal oxide particles B as appropriate). That is, the second metal oxide layer 30 is mainly composed of metal oxide particles, and is usually a so-called porous layer.
The kind of the metal oxide particle B is synonymous with the kind of the metal oxide particle A described above.
The average particle diameter of the metal oxide particles B is 20 to 100 nm. When the average particle diameter is within this range, excellent photoelectric conversion performance can be obtained. Especially, 20-80 nm is preferable and 30-60 nm is more preferable at the point which photoelectric conversion performance is more excellent.
The average particle diameter of the metal oxide particles B is measured by observing the cross section of the second metal oxide layer 30 with an electron microscope, measuring the diameter of at least 100 metal oxide particles, and calculating them. Find on average. In addition, when the metal oxide particle B is not spherical, the major axis is handled as the diameter.

  The layer thickness of the second metal oxide layer 30 is not particularly limited, but is preferably 10 to 500 nm and more preferably 20 to 300 nm in terms of more excellent initial photoelectric conversion performance before bending.

The manufacturing method of the 1st metal oxide layer 28 and the 2nd metal oxide layer 30 will not be restrict | limited especially if the layer formed from the metal oxide particle mentioned above can be manufactured.
For example, the method of using the composition for coating-film formation containing a metal oxide particle is mentioned. For example, a coating film-forming composition containing metal oxide particles having an average particle diameter of 1 to 10 nm is applied on the negative electrode 14 and subjected to heat treatment as necessary to produce the first metal oxide layer 28. The method of doing is mentioned. In addition, when producing the 2nd metal oxide layer 30, the composition for coating-film formation containing the metal oxide particle of an average particle diameter of 20-100 nm is apply | coated on the 1st metal oxide layer 28, and it is the same as the above The second metal oxide layer 30 is produced by the procedure described above.

In addition to the metal oxide particles, the coating film forming composition may contain various solvents as necessary. By including the solvent, it becomes easier to adjust the thickness of the first metal oxide layer 28 or the second metal oxide layer 30.
The kind in particular of solvent used is not restrict | limited, Water or an organic solvent is mentioned. Examples of organic solvents include alcohol solvents (eg, methanol, ethanol, isopropanol), ketone solvents (eg, acetone, methyl ethyl ketone, cyclohexanone), aromatic hydrocarbon solvents (eg, toluene, xylene), amide solvents. (Eg, formamide, dimethylacetamide, N-methylpyrrolidone), nitrile solvents (eg, acetonitrile, propionitrile), ester solvents (eg, methyl acetate, ethyl acetate), carbonate solvents (eg, dimethyl carbonate, diethyl) Carbonate), ether solvents, halogen solvents and the like. Two or more of these solvents may be mixed and used.

  The heat treatment, which is an optional step performed after the coating film-forming composition is applied on the negative electrode 14, easily removes the solvent and the like from the formed coating film, and more bonds between the metal oxide particles. Strengthened. The conditions for the heat treatment are not particularly limited, and optimum conditions are selected according to the type of metal oxide particles used. Especially, it is preferable to implement the heat processing for 5 minutes-4 hours (more preferably 10 minutes-2 hours) at 50-250 degreeC (more preferably 80-180 degreeC).

As another manufacturing method of the first metal oxide layer 28 and the second metal oxide layer 30, in addition to the coating film forming composition including the metal oxide particles described above, the coating film formation including the metal oxide precursor is performed. A method of using the composition for use is also mentioned. For example, a coating film-forming composition containing a metal oxide precursor capable of forming metal oxide particles having a predetermined size is applied onto the negative electrode 14 and subjected to heat treatment as necessary, so that the average particle size is 1 A method of forming the first metal oxide layer 28 by forming metal oxide particles of 10 nm to 10 nm may be mentioned.
In addition, when producing the 2nd metal oxide layer 30, the composition for coating-film formation containing a metal oxide precursor is apply | coated on the 1st metal oxide layer 28, and it is 2nd in the same procedure as the above. A metal oxide layer 30 is produced.

The type of the metal oxide precursor to be used is not particularly limited as long as it is a compound capable of preparing the above-described metal oxide particles having a predetermined size under predetermined conditions. Examples thereof include β-diketonate complexes and metal complexes such as metal chelates.
Examples of the β-diketonate complex include complexes of metal atoms (for example, metal atoms contained in the metal oxide particles described above) and acetylacetone, benzoylacetone, benzoyltrifluoroacetone, benzoyldifluoroacetone, or benzoylfluoroacetone. It is done. More specifically, Zn (acac) _{2 and the} like can be mentioned.
More specifically, when a coating film-forming composition containing Zn (acac) ₂ is applied on the negative electrode 14 and subjected to heat treatment, the metal oxide particles (ZnO) having the predetermined average particle diameter described above are applied. As a result, a desired first metal oxide layer 28 or second metal oxide layer 30 is obtained.
In addition, when using a metal alkoxide as a metal oxide precursor, it is difficult to manufacture the desired 1st metal oxide layer 28 and the 2nd metal oxide layer 30 depending on the kind. For example, when titanium alkoxide or the like is used, it is difficult to control the hydrolysis rate, and the desired first metal oxide layer 28 and second metal oxide layer 30 cannot be obtained.

(Plastic support)
The plastic support 12 is a support that holds various layers including the electron transport layer 16 and imparts flexibility to the organic thin-film solar cell 10, and is not particularly limited in material, thickness, and the like. It can be selected appropriately.

  Specific examples of the material for the plastic support 12 include, for example, polyester resin, methacrylic resin, methacrylic acid-maleic acid copolymer, polystyrene resin, transparent fluororesin, polyimide resin, fluorinated polyimide resin, polyamide resin, and polyamide. Imide resin, polyether imide resin, cellulose acylate resin, polyurethane resin, polyether ether ketone resin, polycarbonate resin, alicyclic polyolefin resin, polyarylate resin, polyether sulfone resin, polysulfone resin, cycloolefin copolymer, fluorene ring modification Thermoplastic resins such as polycarbonate resin, alicyclic modified polycarbonate resin, fluorene ring modified polyester resin, acryloyl compound and the like can be mentioned.

The plastic support 12 is preferably made of a heat resistant material. Specifically, the glass transition temperature (Tg) has heat resistance satisfying at least one of the physical properties of 60 ° C. or higher and the linear thermal expansion coefficient of 40 ppm / ° C. or lower, and is higher with respect to the exposure wavelength. A support formed from a transparent material is preferable.
The Tg and linear expansion coefficient of the plastic support 12 are measured by the plastic transition temperature measurement method described in JIS K 7121 and the linear expansion coefficient test method by thermomechanical analysis of plastic described in JIS K 7197. In the present invention, values measured by this method are used for the Tg and the linear expansion coefficient of the plastic support 12.

As a thermoplastic resin having excellent heat resistance, for example, polyethylene terephthalate (PET: 65 ° C.), polyethylene naphthalate (PEN: 120 ° C.), polycarbonate (PC: 140 ° C.), alicyclic polyolefin (for example, manufactured by Nippon Zeon Co., Ltd.) ZEONOR 1600: 160 ° C., polyarylate (PAr: 210 ° C.), polyethersulfone (PES: 220 ° C.), polysulfone (PSF: 190 ° C.), cycloolefin copolymer (COC: compound of JP 2001-150584 A: 162 ° C.), fluorene ring-modified polycarbonate (BCF-PC: compound of JP 2000-227603 A: 225 ° C.), alicyclic modified polycarbonate (IP-PC: compound of JP 2000-227603 A: 205 ° C.), Acryloyl compounds 2002-80616 compound: 300 [deg.] C. or higher), polyimide, and the like (the numerical values written in abbreviated parenthesis in the parentheses indicate Tg of the resin). Especially, it is preferable to use alicyclic polyolefin etc. for the use for which transparency is especially required.
The Tg and the linear expansion coefficient of the plastic support 12 can be adjusted with an additive or the like.

  The plastic support 12 is preferably transparent to light. In other words, a transparent plastic support is preferred. More specifically, the light transmittance for light in the wavelength range of 400 to 1000 nm is usually preferably 80% or more, more preferably 85% or more, and further preferably 90% or more. The light transmittance is determined by measuring the total light transmittance and the amount of scattered light using the method described in JIS-K7105, that is, an integrating sphere light transmittance measuring device, and subtracting the diffuse transmittance from the total light transmittance. Can be calculated. In this specification, the value using this method is adopted as the light transmittance.

Although there is no restriction | limiting in particular regarding the thickness of the plastic support body 12, Typically, it is 1-800 micrometers, Preferably it is 10-300 micrometers.
A known functional layer may be provided on the back surface of the plastic support 12 (the surface on which the negative electrode 14 is not provided). Examples of the functional layer include a gas barrier layer, a matting agent layer, an antireflection layer, a hard coat layer, an antifogging layer, and an antifouling layer, which will be described later. In addition, the functional layer is described in detail in paragraph numbers [0036] to [0038] of JP-A-2006-289627.

(Negative electrode 14)
The negative electrode 14 is an electrode layer (electron collecting electrode layer) disposed on the plastic support 12 and has a metal pattern layer 24 and a transparent conductive resin layer 26. The metal pattern layer 24 is composed of a plurality of metal wiring layers 32. When the negative electrode 14 includes the metal pattern layer 24 and the transparent conductive resin layer 26 having excellent ductility, the organic thin film solar cell 10 having excellent flexibility can be obtained.

The layer thickness of the negative electrode 14 is not particularly limited, but is preferably 50 nm to 1 μm, and more preferably 100 nm to 300 nm. The negative electrode 14 preferably has a specific resistance of 8 × 10 ⁻³ Ω · cm or less.
It is preferable that the negative electrode 14 has both high transparency and high conductivity. For high transparency, it is preferable that the area of the opening of the metal pattern layer 24 is large (the opening ratio is large). On the other hand, for high conductivity, the cross-sectional area of the metal wiring layer 32 is preferably large when compared with the same metal.

FIG. 2 is an arrow plan view of the metal pattern layer 24. The metal pattern layer 24 is composed of a plurality of thin metal wiring layers 32, and the metal wiring layers 32 are arranged in stripes. In addition, the pattern shape of the metal pattern layer 24 is not limited to the aspect of FIG. 2, It can design arbitrarily, such as a mesh, a honeycomb, and a rhombus.
The opening ratio of the opening defined by the metal pattern layer 24 is preferably 70% or more and more preferably 80% or more from the viewpoint of transparency. Since the light transmittance and the conductivity are in a trade-off relationship, the larger the aperture ratio, the better. However, in practice, it becomes 95% or less. The opening means an opening region 34 in which the metal pattern layer 24 is not formed, and more specifically, on the negative electrode 14 in which the metal pattern layer 24 is not formed and the transparent conductive resin layer 26 described later is provided. Intended for the area. The aperture ratio means the area ratio of the opening region 34 [area of the opening region 34 / (area of the opening region 34 + area of the metal pattern layer 24)].

The material of the metal wiring layer 32 of the metal pattern layer 24 is not particularly limited as long as it is a highly conductive metal or alloy, but is preferably made of a metal or alloy having a specific resistance of 1 × 10 ⁻⁵ Ω · cm or less. . More specifically, examples of such metals or alloys include gold, platinum, iron, copper, silver, nickel, aluminum, and alloys containing these metals. More preferred examples include copper, silver, or alloys containing these. Copper is preferable from the viewpoint of cost reduction of the metal material itself and migration resistance.

The line width W in plan view of the metal wiring layer 32 is preferably 0.1 to 1 mm or less from the viewpoint of transparency, and the distance D between the metal wiring layers 32 is preferably 3 to 30 mm from the viewpoint of transparency.
The resistance value of the metal wiring layer 32 is preferably 50 Ω / cm or less, more preferably 20 Ω / cm or less, and further preferably 10 Ω / cm or less. In order to realize such conductivity (low resistance), there is a method of increasing the cross-sectional area of the metal wiring layer 32. Further, in order to increase the aperture ratio, it is advantageous that the length (line width) in the film plane direction is short and the length (layer thickness) in the layer thickness direction is large as the cross-sectional shape.
However, when the metal wiring layer 32 having such a cross section is installed, a large step is likely to occur. In the organic thin film solar cell 10, the photoelectric conversion layer 18 is often relatively thin, and if the level difference caused by the metal wiring layer 32 is large, a short circuit (failure) is likely to occur at the corner of the convex portion of the metal wiring layer 32. For this reason, reducing the step due to the metal wiring layer 32 and making the corners of the metal wiring layer 32 convex is more important than increasing the aperture ratio, and a design that sacrifices the aperture ratio to some extent is required. In some cases, it must be taken. That is, as the shape of the cross section of the metal wiring layer 32, a design having a long line width and a thin layer thickness is selected. A preferable ratio between the line width and the layer thickness is in the range of 20000: 1 to 200: 1. Here, the value of the thickest part in the line width is used as the layer thickness.

The cross-sectional shape of the metal wiring layer 32 is a rectangle in FIG.
However, the cross-sectional shape of the metal wiring layer 32 is not limited to this form, and an isosceles trapezoid, an obtuse isosceles triangle, a semicircle, a figure surrounded by an arc and a chord, a figure obtained by deforming these, and the like are possible. At this time, a tapered isosceles trapezoid or an obtuse isosceles triangle is more preferable than a cross section in which the angle of the convex portion is a right angle, such as a rectangle, because a short circuit does not occur. In addition, a cross-sectional shape in which a step is smoothed by a curve or a slope is more preferable than a cross-section having a clear corner because a short circuit is less likely to occur.

  The installation method of the metal pattern layer 24 is not particularly limited, and examples thereof include a vapor deposition method, a sputtering method, a printing method, and an ink jet method, and are appropriately selected. When the metal pattern layer 24 is formed by a printing method or an inkjet method, a binder may be added as long as desired conductivity is not impaired. Examples of binders include polyester resin, methacrylic resin, methacrylic acid-maleic acid copolymer, polystyrene resin, transparent fluororesin, polyimide resin, fluorinated polyimide resin, polyamide resin, polyamideimide resin, polyetherimide resin, cellulose acylate. Rate resin, polyurethane resin, polyether ether ketone resin, polycarbonate resin, alicyclic polyolefin resin, polyarylate resin, polyether sulfone resin, polysulfone resin, cycloolefin copolymer, fluorene ring modified polycarbonate resin, alicyclic modified polycarbonate resin, fluorene Thermoplastic resins such as ring-modified polyester resins and acryloyl compounds, gelatin, polyvinyl alcohol, polyacrylic acid, polyacrylamide, and polyvinyl Pyrrolidone, polyvinyl pyridine, hydrophilic polymers such as polyvinyl imidazole, and the like. These polymers may have a cross-linked structure to increase the film strength.

The configuration of the metal pattern layer 24 is not limited to the mode of FIG. 2, and may have a bus line 36 that intersects the metal wiring layer 32 as shown in FIG. 3.
The bus line 36 is a wiring formed from the viewpoint of ensuring conductivity necessary for the entire operation surface. The preferable line width of the bus line 36 is preferably 1 to 5 mm, more preferably 1 to 3 mm.
The line width of the bus line 36 is not necessarily uniform. The bus line 36 and the metal wiring layer 32 may be made of the same material or different materials. The bus line 36 is usually installed so as to be orthogonal to the metal wiring layer 32, but it may cross at an angle other than 90 degrees. The same definition as the metal wiring layer 32 is applied to the thickness, cross-sectional shape, and material of the bus line 36.

As with the metal wiring layer 32, the interval (pitch) between the bus lines 36 is selected as an optimum condition as a compromise between the large area conductivity and the light transmittance. Specifically, it is determined by the conductivity of the metal wiring layer 32 connecting the adjacent bus lines 36. Typically, it is preferable to select an interval at which the resistance value of the metal wiring layer 32 connecting two adjacent bus lines 36 is 50Ω or less per line. The resistance value is preferably 20Ω or less, particularly preferably 10Ω or less.
The pitch of the bus lines 36 is preferably 40 to 200 mm.

  The bus line 36 may be formed by an evaporation method, or may be formed by a method such as a printing method or an inkjet method. It is advantageous from the viewpoint of cost to form the metal wiring layer 32 and the bus line 36 simultaneously using materials having the same composition. When the metal wiring layer 32 and the bus line 36 are simultaneously produced by roll-to-roll using a mask vapor deposition method, generally, a fixed mask for producing the metal wiring layer 32 and the bus line 36 are produced. A facility having a movable mask is required.

  The transparent conductive resin layer 26 is a layer that covers the metal pattern layer 24 and is filled in the opening region 34 of the metal pattern layer 24. The transparent conductive resin layer 26 needs to be transparent in the emission spectrum or action spectrum range of the organic thin-film solar cell 10, and usually needs to be excellent in light transmittance from visible light to near infrared light. Specifically, when the layer thickness is 0.1 μm, the average light transmittance in the wavelength region of 400 nm to 800 nm is preferably 50% or more, more preferably 75% or more, and 85% or more. Is more preferable.

Although the thickness in particular of the transparent conductive resin layer 26 is not restrict | limited, 20-500 nm is preferable, 30-300 nm is more preferable, 50-200 nm is further more preferable.
The transparent conductive resin layer 26 is not particularly limited as long as it has the above-described transparency and conductivity. However, the transparent conductive resin has a specific resistance of 8 × 10 ⁻³ Ω · cm or less after film formation. It is preferable to use a resin as a main component. Here, the main component means a component having a content of 80% or more based on the total amount of the transparent conductive resin layer 26.
Transparent conductive resins that realize such specific resistance include dispersions of conductive nanomaterials in acrylic polymers (eg, silver nanowires, carbon nanotubes, graphene, etc.), conductive polymers (eg, polythiophene, polypyrrole). Polyaniline, polyphenylene vinylene, polyphenylene, polyacetylene, polyquinoxaline, polyoxadiazole, polybenzothiadiazole, and the like, and polymers having a plurality of these conductive skeletons).

Among these, polythiophene is preferable, and polyethylenedioxythiophene is particularly preferable. These polythiophenes are usually partially oxidized in order to obtain conductivity. The conductivity of the conductive polymer can be adjusted by the degree of partial oxidation (doping amount), and the higher the doping amount, the higher the conductivity. Since polythiophene becomes cationic by partial oxidation, it has a counter anion to neutralize the charge. An example of such a polythiophene is polyethylene dioxythiophene (PEDOTPSS) having polystyrene sulfonic acid as a counter ion.
PEDOT-PSS may contain an organic solvent having a high boiling point for the purpose of increasing conductivity. Examples of the high boiling point organic solvent include ethylene glycol, diethylene glycol, dimethyl sulfoxide, N-methylpyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like.
Specific product examples for realizing the specific resistance include Orgacon (Orgacon) S-305, manufactured by Agfa Co., Ltd. C. A Stark company make and Clevios (Clebios) PH-1000 etc. are mentioned.

Other polymers may be added to the transparent conductive resin layer 26 as long as the desired conductivity is not impaired. Other polymers are added for the purpose of improving coatability and increasing the film strength.
Examples of other polymers include polyester resin, methacrylic resin, methacrylic acid-maleic acid copolymer, polystyrene resin, transparent fluororesin, polyimide, fluorinated polyimide resin, polyamide resin, polyamideimide resin, polyetherimide resin, cellulose Acylate resin, polyurethane resin, polyether ether ketone resin, polycarbonate resin, alicyclic polyolefin resin, polyarylate resin, polyether sulfone resin, polysulfone resin, cycloolefin copolymer, fluorene ring modified polycarbonate resin, alicyclic modified polycarbonate resin, Thermoplastic resins such as fluorene ring-modified polyester resins and acryloyl compounds, gelatin, polyvinyl alcohol, polyacrylic acid, polyacrylamide, polyvinyl pyrone Pyrrolidone, polyvinyl pyridine, hydrophilic polymers such as polyvinyl imidazole, and the like. These polymers may have a cross-linked structure to increase the film strength.

The transparent conductive resin layer 26 is preferably formed by a known means after the above-described metal pattern layer 24 is formed, because the step formed by the metal pattern layer 24 is smoothed by the transparent conductive resin. .
As a preferred embodiment of the method for forming the transparent conductive resin layer 26, a composition containing the transparent conductive resin is applied on the plastic support 12 on which the metal pattern layer 24 is disposed, and heated as necessary. Examples of the method include performing a treatment to form the transparent conductive resin layer 26.

(Photoelectric conversion layer)
The photoelectric conversion layer 18 is a layer that contributes to charge separation of the organic thin film solar cell 10 and has a function of transporting the generated electrons and holes toward electrodes in opposite directions.
The photoelectric conversion layer 18 has a bulk heterostructure in which an electron donating material (hole transport material) that is an organic material and an electron accepting material (electron transport material) are mixed.
The kind of the electron donating material to be used is not particularly limited, and a π electron conjugated compound having a HOMO level of 4.5 eV to 6.0 eV is preferable, and specifically, various arenes (for example, thiophene, carbazole, fluorene). Conjugated polymers, phenylene vinylene-based polymers, porphyrins, phthalocyanines, and the like, which are coupled to each other), silafluorene, thienopyrazine, thienobenzothiophene, dithienosilole, quinoxaline, benzothiadiazole, thienothiophene, and the like. In addition, Chem. Rev. The compound group described as Hole Transport material in 2007, 107, 953-1010, and the porphyrin derivative described in Journal of the American Chemical Society vol. 131, page 16048 (2009) are also applicable.
Among these, a conjugated polymer obtained by coupling a structural unit selected from the group consisting of thiophene, carbazole, fluorene, silafluorene, thienopyrazine, thienobenzothiophene, dithienosilole, quinoxaline, benzothiadiazole, and thienothiophene is particularly preferable. Specific examples include poly-3-hexylthiophene, poly-3-octylthiophene, various polythiophene derivatives described in Journal of the American Chemical Society, Volume 130, page 3020 (2008), Advanced Materials, Volume 19, pages 2295 ( PCDTBT described in 2007), Journal of the American Chemical Society, Volume 130, page 732 (2008), PCDTQx, PCDTPP, PCDTPT, PCDTBX, PCDTPX, Nature Photonics Volume 3, page 649 (2009) PBDTTTT-E, PBDTTTC, PBDTTTT-CF, and PTB7 described in Advanced Materials, Vol. 22, pages 1-4 (2010).

  The kind of the electron-accepting material used is not particularly limited, but a π-electron conjugated compound having an LUMO level of 3.5 eV to 4.5 eV is preferable. Specifically, fullerene and its derivatives, phenylene vinylene-based polymers, naphthalene Examples include tetracarboxylic imide derivatives and perylene tetracarboxylic imide derivatives. Of these, fullerene derivatives are preferred. Specific examples of fullerene derivatives include C60, phenyl-C61-methyl butyrate (fullerene derivatives referred to as PCBM, [60] PCBM, or PC61BM in literature), C70, phenyl-C71-methyl butyrate (in many literatures, etc.) Fullerene derivatives referred to as PCBM, [70] PCBM, or PC71BM), and fullerene derivatives described in Advanced Functional Materials Vol. 19, pages 779-788 (2009), Journal of the American Chemical Society, Vol. 131. 16048 (2009) and the fullerene derivative SIMEF.

  The mixing ratio of the electron donating material and the electron accepting material contained in the photoelectric conversion layer 18 is adjusted so that the conversion efficiency is the highest. The mixing ratio of the electron donating material and the electron accepting material is usually selected from the range of 10:90 to 90:10 in terms of mass ratio. As a method for forming such a mixed organic layer, for example, a co-evaporation method by vacuum deposition may be mentioned. Alternatively, the mixed organic layer can be formed by solvent coating using a solvent in which both the electron donating material and the electron accepting material are dissolved.

The layer thickness of the photoelectric conversion layer 18 is preferably 10 nm to 500 nm, particularly preferably 20 nm to 300 nm.
In the bulk hetero photoelectric conversion layer 18, the electron-donating material and the electron-accepting material may be completely uniformly mixed, or may be phase-separated so as to have a domain size of 1 nm to 1 μm. . The phase separation structure may be an irregular structure or a regular structure. When forming an ordered structure, it may be a top-down ordered structure such as a nanoimprint method or a bottom-up such as self-organization.

In FIG. 1, the photoelectric conversion layer 18 has been described in detail for a bulk hetero type, but is not limited to this mode.
The photoelectric conversion layer may have a planar heterostructure composed of an electron donating layer (hole transport layer) containing an electron donating material and an electron accepting layer (electron transport layer) containing an electron accepting material. When a planar heterostructure is adopted, an electron donating layer is arranged on the positive electrode side, and an electron accepting layer is also arranged on the negative electrode side. Moreover, the hybrid structure which has a bulk hetero layer as an intermediate | middle layer of a planar heterostructure may be sufficient.
In the case of a planar heterostructure, the electron-donating material and the electron-accepting material used in the electron-donating layer and the electron-accepting layer are as described above.

When the photoelectric conversion layer 18 has a planar heterostructure, the thickness of the electron donating layer is not particularly limited, but is preferably 5 to 500 nm, and particularly preferably 10 to 200 nm, from the viewpoint of photoelectric conversion performance.
When the photoelectric conversion layer 18 has a planar heterostructure, the thickness of the electron-accepting layer is not particularly limited, but is preferably 5 to 500 nm and particularly preferably 10 to 200 nm from the viewpoint of photoelectric conversion performance.

(Hole transport layer)
The hole transport layer 20 is a layer provided between the photoelectric conversion layer 18 and the positive electrode 22 so that holes can be easily transported from the photoelectric conversion layer 18 to the positive electrode 22. The hole transport layer 20 also has a function of blocking electrons from moving from the photoelectric conversion layer 18 to the positive electrode 22.
The material used for the hole transport layer 20 is not particularly limited, and a known material can be used. For example, an aromatic amine derivative, a thiophene derivative, a condensed aromatic ring compound, a carbazole derivative, polyaniline, polythiophene, polypyrrole, etc. Is mentioned. In addition, Chem. Rev. A group of compounds described as Hole Transport material in 2007, 107, 953-1010 is also applicable.
Of these, polythiophene is preferable, and polyethylenedioxythiophene is more preferable. Polyethylenedioxythiophene may be doped (partially oxidized) to such an extent that the volume resistivity does not fall below 10 Ωcm. At this time, you may have a counter anion derived from perchloric acid, polystyrene sulfonic acid, etc. for charge neutralization.

As a material used for the hole transport layer 20, molybdenum oxide or polythiophene is preferable, and molybdenum oxide or polyethylenedioxythiophene is more preferable.
The layer thickness of the hole transport layer 20 needs to be selected to be a thickness sufficient to suppress the leakage of electrons. From such a viewpoint, the thickness is preferably 0.1 nm or more, and the upper limit of the thickness is Although there is no restriction | limiting in particular, From a viewpoint of manufacturing efficiency, it is preferable that it is 50 nm or less. A more preferable thickness is in the range of 1 to 20 nm.

(Positive electrode 22)
The positive electrode 22 is an electrode layer disposed on the hole transport layer 22.
The positive electrode 22 is usually a metal electrode layer and is preferably composed of a metal having a relatively low work function. Examples thereof include aluminum, magnesium, silver, and a silver-magnesium alloy.

The layer thickness of the positive electrode 22 is not particularly limited, but is preferably 10 to 500 nm and more preferably 50 to 300 nm from the viewpoint of photoelectric conversion performance.
The positive electrode 22 can be formed by any of various wet film forming methods, dry film forming methods such as vapor deposition methods and sputtering methods, transfer methods, and printing methods. Among these, a printing method, an inkjet method, and a vapor deposition method are preferable.
Examples of the patterning for forming the positive electrode 22 include printing, ink jetting, and the like. Chemical etching by photolithography or the like may be performed, physical etching by a laser or the like may be performed, and vacuum deposition or sputtering may be performed by overlapping a mask.
In the present invention, the formation position of the positive electrode 22 is not particularly limited, and may be formed on the whole hole transport layer 20 or a part thereof.

(Any constituent layer)
The organic thin film solar cell 10 shown in FIG. 1 includes the plastic support 12, the negative electrode 14, the electron transport layer 16, the photoelectric conversion layer 18, the hole transport layer 20, and the positive electrode 22 described above, but is not limited to this form. If necessary, it may have a layer other than the above.
An example is shown below.

(Upper sealing member)
The organic thin film solar cell may further have an upper sealing member on the positive electrode 22. By arrange | positioning an upper sealing member, an organic thin-film solar cell is isolated from the atmosphere of the external field, and photoelectric conversion performance improves more.
The upper sealing member may include a protective layer, a gas barrier layer, a contact material layer, or a plastic support. A preferable configuration example of the upper sealing member includes a laminate in which a protective layer, an adhesive layer, a gas barrier layer, and a plastic support are laminated in this order from the positive electrode 22 side. Below, the structure of each layer is explained in full detail.

Protective layer is _{typically, MgO, SiO, SiO 2,} Al 2 O 3, Y 2 O 3, TiO metal oxides such as _2, metal nitrides such as SiN _x, metal nitride oxide such as SiN _x O _{y, MgF 2, LiF, AlF 3,} CaF 2 , etc. of the metal fluoride, polyethylene, polypropylene, polyvinylidene fluoride, or a polymer such as poly-para-xylylene and the like. Of these, metal oxides, nitrides, and nitride oxides are preferable, and silicon, aluminum oxides, nitrides, and nitride oxides are particularly preferable. The protective layer may be a single layer or a multilayer structure of different materials selected from the above.

  The method for forming the protective layer is not particularly limited, and for example, vacuum deposition, sputtering, reactive sputtering, MBE (molecular beam epitaxy), cluster ion beam, ion plating, plasma polymerization (high frequency) Excited ion plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, vacuum ultraviolet CVD method, coating method, printing method, transfer method and the like can be applied.

The gas barrier layer is not particularly limited as long as it has a gas barrier property. Usually, the gas barrier layer is an inorganic layer (sometimes referred to as an inorganic layer). Typical examples of the inorganic substance contained in the inorganic layer include boron, magnesium, aluminum, silicon, titanium, zinc, tin oxide, nitride, oxynitride, carbide, hydride, and the like. These may be pure substances, or may be a mixture of multiple compositions or a gradient material layer. Among these, aluminum oxide, nitride or oxynitride, or silicon oxide, nitride or oxynitride is preferable.
As the gas barrier layer, an organic layer can be used, and a polymer of (meth) acrylate is preferable because it is low in cost, ready for production, and has high transparency.

The inorganic layer as the gas barrier layer may be a single layer or a laminate of a plurality of layers. When the gas barrier layer has a laminated structure, it may be a laminate of an inorganic layer and an organic layer, or may be an alternating laminate of a plurality of inorganic layers and a plurality of organic layers. Specific examples of the organic layer and the inorganic layer and the lamination method are described in JP 2010-87339 A. The term “organic polymer layer” in this publication corresponds to the term organic layer in the present invention.
Although there is no limitation in particular about the thickness of the inorganic layer as a gas barrier layer, it is attached to 1 layer, and is in the range of 5-500 nm normally, Preferably it is 10-200 nm. The inorganic layer may have a laminated structure including a plurality of sublayers. In this case, each sublayer may have the same composition or a different composition.
Although there is no limitation in particular regarding the thickness of the organic layer as a gas barrier layer, 300-3000 nm is preferable per one layer.
Further, as disclosed in US Patent Publication No. 2004-46497, the interface between the inorganic layer and the organic layer adjacent thereto is not clear, and the composition is a layer whose composition changes continuously in the layer thickness direction. Also good.

The adhesive is not particularly limited, and for example, an emulsion type adhesive, an adhesive for wax hot melt lamination, an adhesive for dry lamination, and the like are preferable.
Examples of the emulsion type adhesive include a coating agent in which thermoplastic elastomer, LDPE, IO (ionomer), PVDC, PE (polyethylene) wax and the like are dispersed.
Examples of the wax hot melt lamination adhesive include PVDC (OPP (biaxially stretched polypropylene film, nylon film, PET film, PVA film) coated with polyvinylidene chloride resin).
Examples of adhesives for dry lamination include vinyl chloride / vinyl acetate copolymer, EVA (ethylene / vinyl acetate copolymer), ionomer copolymer, polyvinylidene chloride, ethylene / vinyl alcohol copolymer, nitrocellulose, Examples include cellulose acetate and silicone.

  The definition of the plastic support is similar to that already described.

  The installation method of the upper sealing member described above is not particularly limited. For example, first, a protective layer is provided on the positive electrode 22. Then, the sealing film (plastic support) which installed the gas barrier layer on the plastic support body is produced, and a sealing film is adhere | attached on the said protective layer through an adhesive agent. When transparency is not required on the upper part, a method of adhering a gas barrier film in which a metal foil is laminated on a protective layer may be used.

  Further, the gas barrier layer described above may be disposed on the surface of the plastic support 12 on the negative electrode 14 side. In other words, a gas barrier layer may be disposed between the plastic support 12 and the negative electrode 14. The aspect of the gas barrier layer is as described above.

[Second Embodiment]
FIG. 4 is a cross-sectional view schematically showing the layer configuration of the second embodiment of the organic thin-film solar cell of the present invention. The organic thin film solar cell 100 includes a plastic support 12, a negative electrode 14, an electron transport layer 16, a photoelectric conversion layer 18, a hole transport layer 20, and a positive electrode 22 in this order. The negative electrode 14 has a metal pattern layer 24 and a transparent conductive resin layer 26. The electron transport layer 16 includes a second metal oxide layer 30 and a first metal oxide layer 28. Similar to the organic thin film solar cell 100, the organic thin film solar cell 10 is a so-called inverted organic thin film solar cell, and the surface on the plastic support 12 side is a light receiving surface and is an electrode on the side close to the plastic support. Corresponds to the negative electrode.
The organic thin film solar cell 100 shown in FIG. 4 has the same configuration as the organic thin film solar cell 10 shown in FIG. 1 except that the stacking order of the first metal oxide layer 28 and the second metal oxide layer 30 is different. Therefore, the same constituent elements are denoted by the same reference numerals, and the description thereof is omitted.
In the organic thin film solar cell 100, the second metal oxide layer 30 is disposed on the negative electrode 14, and the first metal oxide layer 28 is disposed on the second metal oxide layer 30. Even if the stacking order of the first metal oxide layer 28 and the second metal oxide layer 30 is different, like the organic thin film solar cell 10 described above, the organic thin film solar cell 100 is excellent in photoelectric conversion even after being bent. Indicates performance.

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

<Example 1>
A gas barrier layer is formed on one surface of a 100 μm thick polyethylene naphthalate film (hereinafter abbreviated as a PEN film), which is a plastic support, and a negative electrode, an electron transport layer, a photoelectric conversion layer, and a hole transport layer are formed on the other surface of the PEN film. The organic thin film solar cell of Example 1 was produced by laminating the positive electrode.
The detailed procedure is shown below.

[Formation of gas barrier layer]
On the PEN film, using a wire bar, a polymerizable composition (EB-3702 (13 g) manufactured by Daicel Cytec Co., Ltd., light acrylate TMP-A (6 g) manufactured by Kyoeisha Chemical Co., Ltd.), KAYAMER PM-21 (1 g) manufactured by Nippon Kayaku Co., Ltd. Lambberti UV polymerization initiator ESACURE KTO-46 (0.5 g), 2-butanone 190 g mixed solution) was applied. After drying, the organic layer is cured by irradiating with ultraviolet rays from a high-pressure mercury lamp (accumulated dose 1 J / cm ² ) in a chamber in which the oxygen concentration is 0.1% by the nitrogen substitution method. A 5 μm organic layer was formed.
An inorganic layer (aluminum oxide layer) was formed on the organic layer using a sputtering apparatus. Aluminum was used as a target, argon was used as a discharge gas, and oxygen was used as a reaction gas. The film forming pressure was 0.1 Pa, and the reaching layer thickness was 40 nm.
On the obtained laminate, the polymerizable composition was applied and cured by the same method as described above to form an organic layer having a layer thickness of 1.5 μm.
Thus, the gas barrier layer which consists of three layers, an organic layer, an inorganic layer, and an organic layer, was formed on the PEN film. When the water vapor transmission rate at 40 ° C. and 90% relative humidity of the PET film having the gas barrier layer was measured using a water vapor transmission rate measuring device (manufactured by MOCON, PERMATRAN-W3 / 31), the detection limit value of this measurement (0.005 g / m ² / day) or less.

[Formation of negative electrode]
Each PEN film on which a gas barrier layer is formed is cut into 25 mm squares, a mask for a 25 mm square substrate is set in a vacuum deposition apparatus, and a silver metal wiring layer is deposited on the gas barrier layer by a resistance heating method to a thickness of 100 nm. A pattern layer was formed. Deposition is performed by deposition, and the deposition pattern is a parallel stripe having a line width of 0.3 mm, a line length of 20 mm, and a line interval of 4 mm. In order to form this pattern, a stainless steel mask having a thickness of 0.1 mm was set below the PEN film with a clearance of 1 mm.
Next, the ends of the metal wiring layers in the metal pattern layer were brought into contact with each other using a silver paste.

[Formation of transparent conductive resin layer]
Next, an aqueous dispersion of polyethylene dioxythiophene / polystyrene sulfonic acid (abbreviation: PEDOT-PSS) (manufactured by Agfa, Olgacon S-305) was spin-coated from the upper surface of the surface on which the metal pattern layer was formed. Next, this film was heat-dried at 110 ° C. for 20 minutes to form a transparent conductive resin layer made of a transparent conductive resin. At this time, the thickness of the transparent conductive resin layer was 100 nm.

[Formation of electron transport layer]
Next, an ethanol solution containing Zn (acac) ₂ (manufactured by Wako Pure Chemical Industries, Ltd.) was applied on the transparent conductive resin layer and subjected to heat treatment at 160 ° C. for 20 minutes to form a first metal oxide layer. . The content of Zn (acac) ₂ in the ethanol solution was 0.5 parts by mass with respect to 100 parts by mass of ethanol.
When the surface of the obtained first metal oxide layer was observed with an atomic force microscope, it was confirmed that the first metal oxide layer was a layer formed of ZnO particles having an average particle diameter of 5 nm. The layer thickness of the first metal oxide layer was 80 nm.

Next, a solution obtained by diluting an ethanol solution containing ZnO particles (manufactured by Aldrich) eight times with ethanol was applied onto the first metal oxide layer and dried as it was to form a second metal oxide layer. In addition, the average particle diameter of the ZnO particle | grains in a solution was 40 nm, and the content was 5 mass parts with respect to 100 mass parts of ethanol solvents.
When the obtained second metal oxide layer was observed with an electron microscope, it was confirmed that the second metal oxide layer was a porous layer formed of ZnO particles having an average particle diameter of 40 nm as a starting material. . The layer thickness of the second metal oxide layer was 100 nm.

[Formation of photoelectric conversion layer]
A bulk hetero layer was formed as the photoelectric conversion layer. 20 mg of P3HT (poly-3-hexylthiophene, Lisicon SP-001 (trade name), manufactured by Merck) and 14 mg of ICBA (indene C60 bis-adduct, manufactured by Aldrich) were dissolved in 1 ml of chlorobenzene to obtain a bulk hetero layer coating solution. . This was spin-coated on the second metal oxide layer to form a bulk hetero layer. The rotation speed of the spin coater was 500 rpm, and the dry layer thickness was 180 nm.
Then, it heated for 15 minutes at 130 degreeC using the hotplate.

[Formation of hole transport layer]
The surface of the photoelectric conversion layer produced above was spin-coated with Plexcornics OC-1200 manufactured by Plextronics, and heated and dried at 100 ° C. for 20 minutes to form a hole transport layer. At this time, the layer thickness of the hole transport layer was 40 nm.

[Formation of positive electrode]
Aluminum was deposited on the hole transport layer to a thickness of 100 nm to form a positive electrode. At this time, mask vapor deposition was performed so that the effective area of photoelectric conversion was 1 cm ² .

[Measurement of power generation efficiency]
The organic thin-film solar cell obtained above was irradiated with simulated sunlight of AM1.5G and 80 mW / cm ² using a Pexel Technologies L12 solar simulator, while measuring the source measure unit (SMU2400, manufactured by KEITHLEY) ) Was used to measure the generated current value in the voltage range of −0.1 V to 1.0 V. The obtained current-voltage characteristics were evaluated using a Pexel Technologies IV curve analyzer, and the conversion efficiency (%), which is the initial battery characteristics, was calculated as a characteristic parameter. The measurement results are shown in Table 1 below.

[Measurement of power generation efficiency (measurement after bending test)]
Next, the following bending test was performed. Then, the conversion efficiency of the organic thin film solar cell after a bending test was measured by the said method. The ratio of the conversion efficiency before and after the bending test (conversion efficiency after the bending test / conversion efficiency before the bending test) was determined and evaluated according to the following criteria. In practice, it is necessary to be A. The measurement results are shown in the “Bend test evaluation” column of Table 1 below.
“A”: When the ratio is 0.95 or more and 1.00 “B”: When the ratio is 0.60 or more and less than 0.95 “C”: When the ratio is less than 0.60

  In the bending test, an organic thin-film solar cell is wound around a stainless steel pipe with a diameter of 30 mm, 180 degrees so that the photoelectric conversion layer installation surface is on the outside, and immediately returned to the original flat shape 100 times. It was.

<Example 2>
A procedure similar to that of Example 1 was used except that a TiO ₂ -containing solution (manufactured by Solaronix, average particle diameter of TiO ₂ ) was used instead of the ethanol solution containing Zn (acac) ₂ (manufactured by Wako Pure Chemical Industries, Ltd.). An organic thin film solar cell was manufactured and various measurements were performed. The measurement results are summarized in Table 1 below.

<Example 3>
Except having changed the thickness of the 1st metal oxide layer from 80 nm to 20 nm, the organic thin film solar cell was manufactured in the same procedure as Example 2, and various measurements were performed. The measurement results are summarized in Table 1 below.

<Example 4>
Except having changed the thickness of the 1st metal oxide layer from 80 nm to 20 nm, the organic thin film solar cell was manufactured in the same procedure as Example 1, and various measurements were performed. The measurement results are summarized in Table 1 below.

<Example 5>
Except having changed the thickness of the 1st metal oxide layer from 80 nm to 50 nm, the organic thin film solar cell was manufactured in the same procedure as Example 1, and various measurements were performed. The measurement results are summarized in Table 1 below.

<Example 6>
Except having changed the thickness of the 1st metal oxide layer from 80 nm to 150 nm, the organic thin-film solar cell was manufactured in the same procedure as Example 1, and various measurements were performed. The measurement results are summarized in Table 1 below.

<Example 7>
Except for changing the thickness of the second metal oxide layer from 100 nm to 200 nm, an organic thin film solar cell was produced in the same procedure as in Example 1, and various measurements were performed. The measurement results are summarized in Table 1 below.

<Example 8>
Except having changed the thickness of the 2nd metal oxide layer from 100 nm to 400 nm, the organic thin-film solar cell was manufactured in the same procedure as Example 1, and various measurements were performed. The measurement results are summarized in Table 1 below.

<Example 9>
Except that the positive electrode was manufactured according to the following procedure, an organic thin film solar cell was manufactured according to the same procedure as in Example 1, and various measurements were performed. The measurement results are summarized in Table 1 below.
The positive electrode was coated with silver ink to a thickness of 1 μm using a DMP-2831 type inkjet device manufactured by Fuji Film Dimatics. As a post-bake, it was heated in air at 140 ° C. for 30 minutes. As the silver ink, Harima Kasei NANOPASTE (Ag) NPS-JL was used.

<Example 10>
After the formation of the positive electrode, Tosero made EVA, solar cell sealing EVA (ethylene-vinyl acetate copolymer mixed with thermosetting agent, 0.5 mm thickness, trade name Solar EVA) on the positive electrode as an adhesive The produced PEN film having a gas barrier layer was superposed and vacuum laminated at 140 ° C. At this time, it bonded so that a gas barrier layer might become the EVA side.
The conversion efficiency of the obtained organic thin film solar cell with an upper sealing member was measured in the same manner as in Example 1. The measurement results are summarized in Table 1 below.

<Comparative Example 1>
Except that the second metal oxide layer was not formed, an organic thin film solar cell was produced in the same procedure as in Example 1, and various measurements were performed. The measurement results are summarized in Table 1 below.

<Comparative Example 2>
Except that the second metal oxide layer was not formed, an organic thin film solar cell was produced in the same procedure as in Example 2, and various measurements were performed. The measurement results are summarized in Table 1 below.

<Comparative Example 3>
Except that the first metal oxide layer was not formed, an organic thin film solar cell was produced in the same procedure as in Example 1, and various measurements were performed. The measurement results are summarized in Table 1 below.

<Comparative Example 4>
Instead of a solution obtained by diluting an ethanol solution containing ZnO particles (Aldrich) eight times with ethanol, an aqueous dispersion containing TiO ₂ particles (manufactured by JGC Catalysts & Chemicals, HPW-200C, average particle size: 200 nm) is used. Except for the use, an organic thin-film solar cell was produced in the same procedure as in Example 8, and various measurements were performed. The measurement results are summarized in Table 1 below.

<Comparative Example 5>
Instead of using an ethanol solution containing Zn (acac) ₂ (manufactured by Wako Pure Chemical Industries, Ltd.), an aqueous dispersion containing TiO ₂ particles (manufactured by JGC Catalysts & Chemicals, HPW-18NR, average particle size: 16 nm) was used. Manufactured the organic thin film solar cell in the same procedure as Example 1, and performed various measurements. The measurement results are summarized in Table 1 below.

<Comparative Example 6>
Instead of a solution obtained by diluting an ethanol solution containing ZnO particles (Aldrich) eight times with ethanol, an aqueous solution containing TiO ₂ particles (manufactured by JGC Catalysts & Chemicals, HPW-18NR, average particle size: 16 nm) is used. Except for the above, an organic thin film solar cell was produced in the same procedure as in Example 1, and various measurements were performed. The measurement results are summarized in Table 1 below.

<Comparative Example 7>
Instead of a solution obtained by diluting an ethanol solution containing ZnO particles (Aldrich) eight times with ethanol, an aqueous dispersion containing TiO ₂ particles (manufactured by JGC Catalysts & Chemicals, HPW-18NR, average particle size: 16 nm) The organic thin-film solar cell was manufactured in the same procedure as in Example 2 except that was used, and various measurements were performed. The measurement results are summarized in Table 1 below.

<Comparative Example 8>
Instead of an ethanol solution containing Zn (acac) ₂ (manufactured by Wako Pure Chemical Industries, Ltd.), a solution containing the following titanium oxide precursor was used to produce an organic thin film solar cell in the same procedure as in Example 1, Various measurements were performed.
The titanium oxide precursor solution was prepared by mixing 10 ml of titanium tetraisopropoxide, 50 ml of 2-methoxyethanol and 5 ml of ethanolamine, heating at 80 ° C. for 2 hours, and then heating at 120 ° C. for 1 hour, followed by toluene. 15 ml was added to obtain a titanium oxide precursor solution. The measurement results are summarized in Table 1 below.
In the organic thin film solar cell obtained in Comparative Example 8, an amorphous TiO ₂ layer formed by hydrolysis / condensation reaction of a titanium oxide precursor is formed instead of the first metal oxide layer. The TiO ₂ layer does not contain metal oxide particles having a predetermined average particle size.

As shown in Table 1, the organic thin-film solar cell of the present invention exhibits excellent photoelectric conversion performance before the bending test, has almost no deterioration in photoelectric conversion performance after the bending test, and has excellent bending resistance. Was confirmed.
In particular, as can be seen from the comparison of Examples 1 to 6, Examples 1 to 5 in which the thickness of the first metal oxide layer is in the range of 10 to 100 nm show excellent photoelectric conversion performance before the bending test. It was confirmed.
Further, as can be seen from the comparison between Examples 1, 7 and 8, in Examples 1 and 7 in which the thickness of the second metal oxide layer is in the range of 10 to 200 nm, excellent photoelectric conversion performance is obtained before the bending test. It was confirmed to show.
Furthermore, as can be seen from the comparison between Examples 1 and 2 or Examples 3 and 4, when the same metal oxide (ZnO) is used in the first metal oxide layer and the second metal oxide layer, It was confirmed that the photoelectric conversion performance was excellent.

On the other hand, in the embodiments shown in Comparative Examples 1 to 8 that do not have the configuration of the organic thin film solar cell of the present invention, the photoelectric conversion performance before the bending test is inferior, or the photoelectric conversion performance after the bending test is deteriorated. .
More specifically, as shown in Comparative Examples 1 and 2, when the second metal oxide layer was not provided, the photoelectric conversion performance before the bending test was particularly poor.
As shown in Comparative Example 3, when the first metal oxide layer was not provided, particularly, the photoelectric conversion performance after the bending test was deteriorated.
As shown in Comparative Example 4, when the size of the metal oxide particles used for the second metal oxide layer was out of the range, the photoelectric conversion performance before the bending test was particularly poor.
As shown in Comparative Example 5, when the size of the metal oxide particles used for the first metal oxide layer was out of the range, the photoelectric conversion performance after the bending test was deteriorated in particular.
As shown in Comparative Examples 6 and 7, when the size of the metal oxide particles used in the second metal oxide layer is out of the range, the photoelectric conversion performance before the bending test is inferior, and the photoelectric conversion performance after the bending test. Degradation also occurred.
As shown in Comparative Example 8, when the first metal oxide layer is an amorphous TiOx layer (dense layer) formed by hydrolysis / condensation reaction of metal alkoxide, the photoelectric conversion performance before the bending test is inferior and the bending test is performed. Later degradation of the photoelectric conversion performance also occurred.

[Measurement of power generation efficiency (measurement after moisture resistance test)]
The organic thin-film solar cell obtained in Example 10 was left in a high-temperature and high-humidity chamber at 60 ° C. and 90% relative humidity for 100 hours, and then the conversion efficiency was measured by the above method. The ratio of the conversion efficiency before and after the moisture resistance test (conversion efficiency after the moisture resistance test / conversion efficiency before the moisture resistance test) was determined and evaluated according to the following criteria. In practice, it is necessary to be A.
“A”: When the ratio is 0.95 or more and 1.00 “B”: When the ratio is 0.60 or more and less than 0.95 “C”: When the ratio is less than 0.60 In Example 10 The evaluation of the obtained organic thin film solar cell was “A”, and it was confirmed that excellent photoelectric conversion characteristics were exhibited even after the high temperature and high humidity test.

DESCRIPTION OF SYMBOLS 10,100 Organic thin film solar cell 12 Plastic support body 14 Negative electrode 16 Electron transport layer 18 Photoelectric conversion layer 20 Hole transport layer 22 Positive electrode 24 Metal pattern layer 26 Transparent conductive resin layer 28 1st metal oxide layer 30 2nd metal oxide Physical layer 32 Metal wiring layer 34 Open area 36 Bus line

Claims (5)

On the plastic support, at least a negative electrode, an electron transport layer, a photoelectric conversion layer containing at least an organic material, a hole transport layer, and a positive electrode in this order,
The negative electrode includes a metal pattern layer and a transparent conductive resin layer,
The electron transport layer includes a first metal oxide layer formed from metal oxide particles having an average particle diameter of 1 to 10 nm, and a second metal oxide layer formed from metal oxide particles having an average particle diameter of 20 to 100 nm. An organic thin film solar cell including at least two layers.   The organic thin-film solar cell according to claim 1, wherein the metal oxide particles include metal oxide particles having at least one metal atom selected from the group consisting of zinc, titanium, tin, and tungsten.   The organic thin-film solar cell according to claim 1 or 2, wherein the first metal oxide layer has a thickness of 10 to 100 nm.   The organic thin-film solar cell in any one of Claims 1-3 whose layer thickness of a said 2nd metal oxide layer is 10-200 nm.   Furthermore, the organic thin-film solar cell in any one of Claims 1-4 which has a gas barrier layer.

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