Stacked body, organic thin-film solar cell, method for manufacturing a stacked body, and method for manufacturing an organic thin-film solar cell

Abstract

The present invention provides a laminate capable of obtaining an organic thin film solar cell (1) having excellent output characteristics and transmittance. The laminate has a titanium oxide layer (3) serving as an electron transport layer disposed on a member (2) serving as a light-transmitting electrode layer. The thickness of the titanium oxide layer (3) is 1.0 nm or more and 200.0 nm or less. The titanium oxide layer contains indium oxide and metallic indium. When the content of titanium element is Ti, the content of indium oxide is InOx, and the content of metallic indium is InM, InOx / Ti is 0.50 or more and 20.00 or less in terms of atomic ratio, and InM / Ti is less than 0.100 in terms of atomic ratio.

Description

Technical Field

[0001] The present invention relates to a laminate, an organic thin film solar cell, a method for manufacturing a laminate, and a method for manufacturing an organic thin film solar cell. Background Art

[0002] Conventionally, as an organic thin film solar cell, a "normal type" organic thin film solar cell having a transparent electrode layer, a hole transport layer, an organic semiconductor layer, an electron transport layer, and a collector layer in this order has been known.

[0003] In addition, in recent years, from the viewpoint of improving durability and the like, a "trans type" organic thin film solar cell having a transparent electrode layer, an electron transport layer, an organic semiconductor layer, a hole transport layer, and a collector layer in this order has been proposed (see Patent Document 1).

[0004] Prior Art Documents

[0005] Patent Documents

[0006] Patent Document 1: Japanese Patent Application Laid-Open No. 2009-146981 Summary of the Invention

[0007] Problems to be Solved by the Invention

[0008] As described above, an organic thin film solar cell has, for example, a transparent electrode layer, an electron transport layer, an organic semiconductor layer, a hole transport layer, and a collector layer in this order.

[0009] When such an organic thin film solar cell is used in an actual living environment, it is required to exhibit good output characteristics.

[0010] In Patent Document 1, a titanium oxide layer serving as an electron transport layer was formed by a sol-gel method. The titanium oxide layer formed by the sol-gel method is amorphous and contains oxygen defects, and thus it is considered that the electron migration resistance is reduced.

[0011] However, as a result of research by the present inventors, it has been found that an organic thin film solar cell in which an electron transport layer is formed by a sol-gel method has insufficient output characteristics.

[0012] In addition, in recent years, it has been proposed to replace a glass window used in a house, a vehicle, etc. with an organic thin film solar cell having good transmittance. In this case, excellent transmittance is required for the titanium oxide layer serving as an electron transport layer.

[0013] Accordingly, an object of the present invention is to provide a laminate serving as a transparent electrode layer and an electron transport layer of a reverse organic thin-film solar cell having a transparent electrode layer, an electron transport layer, an organic semiconductor layer, a hole transport layer, and a collector layer in this order, and an organic thin-film solar cell having excellent output characteristics and transmittance can be obtained from the laminate.

[0014] In addition, an object of the present invention is to provide a new method for manufacturing the above laminate.

[0015] Means for Solving the Problem

[0016] The present inventors conducted intensive studies and found that the above object can be achieved by adopting the following configuration, thereby completing the present invention.

[0017] That is, the present invention provides the following [1] to [7].

[0018] [1] A laminate which is a laminate of the above transparent electrode layer and the above electron transport layer of an organic thin-film solar cell having a transparent electrode layer, an electron transport layer, an organic semiconductor layer, a hole transport layer, and a collector layer in this order, and which has a member serving as the above transparent electrode layer and a titanium oxide layer serving as the above electron transport layer disposed on the member serving as the above transparent electrode layer, the thickness of the titanium oxide layer being 1.0 nm or more and 200.0 nm or less, the titanium oxide layer containing indium oxide and metallic indium, and when the content of titanium element is Ti, the content of indium oxide is InOx, and the content of metallic indium is InM, InOx / Ti is 0.50 or more and 20.00 or less in terms of atomic ratio, and InM / Ti is less than 0.100 in terms of atomic ratio.

[0019] [2] An organic thin-film solar cell having a transparent electrode layer, an electron transport layer, an organic semiconductor layer, a hole transport layer, and a collector layer in this order, which uses the laminate described in the above [1].

[0020] [3] A method for manufacturing a laminate, which is a method for manufacturing the laminate described in the above [1], and in which a member serving as the above transparent electrode layer is cathodically polarized in a treatment liquid containing a Ti component, and then anodically polarized, whereby the titanium oxide layer is formed on the member serving as the above transparent electrode layer.

[0021] [4] The method for manufacturing a laminate according to the above [3], wherein the Ti content in the treatment liquid is 0.004 mol / L or more and 1.300 mol / L or less.

[0022] [5] The manufacturing method of the laminate as described in [3] or [4] above, wherein the above-mentioned Ti component is at least one selected from the group consisting of hexafluorotitanic acid, potassium hexafluorotitanate, sodium hexafluorotitanate, ammonium hexafluorotitanate, ammonium oxotitanate oxalate, potassium oxotitanate oxalate dihydrate, titanium sulfate, and titanium lactate.

[0023] [6] The manufacturing method of the laminate as described in any one of [3] to [5] above, wherein the member that will become the above-mentioned light-transmissive electrode layer is used as the cathode, and electrolysis is carried out at a current density of 0.01 A / dm 2 or more and 5.00 A / dm 2 or less, and then, the member that will become the above-mentioned light-transmissive electrode layer is used as the anode, and electrolysis is carried out at a current density of 0.01 A / dm 2 or more and 5.00 A / dm 2 or less.

[0024] [7] A manufacturing method of an organic thin-film solar cell, wherein the laminate described in [1] above is used to manufacture an organic thin-film solar cell having a light-transmissive electrode layer, an electron transport layer, an organic semiconductor layer, a hole transport layer, and a collector layer in sequence.

[0025] Advantages of the Invention

[0026] According to the present invention, it is possible to provide a laminate that becomes a light-transmissive electrode layer and an electron transport layer of an organic thin-film solar cell having a light-transmissive electrode layer, an electron transport layer, an organic semiconductor layer, a hole transport layer, and a collector layer in sequence, and an organic thin-film solar cell having excellent output characteristics and transmittance can be obtained from this laminate.

[0027] In addition, according to the present invention, a new method for manufacturing the above laminate can be provided. Description of the Drawings

[0028] Figure 1 is a schematic cross-sectional view showing an organic thin-film solar cell.

[0029] Figure 2 is a schematic cross-sectional view showing the laminate. Detailed Description

[0030] [Organic Thin-Film Solar Cell]

[0031] First, the organic thin-film solar cell 1 will be described based on Figure 1 the following.

[0032] Figure 1 is a schematic cross-sectional view showing the organic thin-film solar cell 1. The organic thin-film solar cell 1 has, for example, a light-transmissive electrode layer 2, an electron transport layer 3, an organic semiconductor layer 4, a hole transport layer 5, and a collector layer 6 in sequence.

[0033] The thickness of the light-transmissive electrode layer 2 is based on the thickness of the member 8 (reference Figure 2 ).

[0034] The thickness of the electron transport layer 3 is based on the thickness of the titanium oxide layer 9 (reference Figure 2 ).

[0035] The thicknesses of the organic semiconductor layer 4, the hole transport layer 5, and the collector layer 6 can be appropriately set.

[0036] As the light-transmissive electrode layer 2, films of conductive metal oxides such as ITO (Indium Tin Oxide) films can be preferably cited. The light-transmissive electrode layer 2 can be disposed on a transparent substrate such as a glass substrate or a resin film.

[0037] As the electron transport layer 3, for example, a titanium oxide layer containing titanium oxide (TiO2) as an n-type semiconductor can be cited.

[0038] As the organic semiconductor layer 4, for example, a layer containing poly-3-hexylthiophene (P3HT) as a polythiophene derivative and [6,6]-phenyl-C 61 -butyric acid methyl ester (PCBM) can be cited.

[0039] The mass ratio of P3HT to PCBM (P3HT:PCBM) is preferably 5:3 to 5:6, more preferably 5:3 to 5:4.

[0040] Such an organic semiconductor layer 4 can further contain additives such as a conductive material and a dye.

[0041] As the conductive material, for example, conductive materials of polyacetylene series, polypyrrole series, polythiophene series, poly(phenylene) series, poly(phenylene vinylene) series, polythiophene vinylene series, poly(3,4-ethylenedioxythiophene) series, polyfluorene series, polyaniline series, polyacene series (however, PEDOT / PSS described later is excluded) can be cited.

[0042] As the dye, for example, cyanine series, merocyanine series, phthalocyanine series, naphthalocyanine series, azo series, quinone series, quinone imine series, quinacridone series, squarylium series, triphenylmethane series, xanthene series, porphyrin series, perylene series, indigo series dyes can be cited.

[0043] The content of the additive is preferably 1 to 100 parts by mass, more preferably 1 to 40 parts by mass, relative to 100 parts by mass in total of P3HT and PCBM.

[0044] As the material of the hole transport layer 5, PEDOT / PSS, V2O5, MoO3, etc. can be cited, and PEDOT / PSS is preferred.

[0045] PEDOT / PSS is a polymer compound formed by integrating PEDOT (poly-3,4-ethylenedioxythiophene) and PSS (polystyrene sulfonic acid), and is sometimes expressed as PEDOT:PSS.

[0046] As the collector layer 6, for example, an Au electrode layer, an Ag electrode layer, an Al electrode layer, a Ca electrode layer, etc. can be cited, and among them, an Au electrode layer is preferred.

[0047] [Laminated body]

[0048] Next, based on Figure 2 the laminated body 7 of the transparent electrode layer 2 and the electron transport layer 3 that form the organic thin-film solar cell 1 (refer to Figure 1 ) will be described.

[0049] Figure 2 is a cross-sectional view schematically showing the laminated body 7. The laminated body 7 has a member 8 that forms the transparent electrode layer 2 (refer to Figure 1 ) and a titanium oxide layer 9 that forms the electron transport layer 3 (refer to Figure 1 ) disposed on the member 8.

[0050] <Member that forms the transparent electrode layer>

[0051] The member 8 that forms the transparent electrode layer 2 (refer to Figure 1 ) is preferably a member having conductivity, and more preferably a member containing indium oxide.

[0052] When the member 8 is a member containing indium oxide, it is further preferably a member containing indium tin oxide (ITO), and particularly preferably an ITO film.

[0053] The member 8 can be disposed on a transparent substrate such as a glass substrate or a resin film.

[0054] For example, the thickness of the member 8 as an ITO film can be appropriately set according to the obtained organic thin-film solar cell 1 (refer to Figure 1 ), preferably 20 nm or more, more preferably 80 nm or more, and further preferably 150 nm or more. On the other hand, it is preferably 500 nm or less, more preferably 400 nm or less, and further preferably 300 nm or less.

[0055] The thickness of the member 8 is a value obtained by forming a cross-section of the member 8 using a focused ion beam and measuring the formed cross-section using a scanning electron microscope.

[0056] <Titanium oxide layer>

[0057] The titanium oxide layer 9 is a layer containing titanium oxide.

[0058] In addition, as described later, the titanium oxide layer 9 contains indium oxide and metallic indium.

[0059] "Thickness"

[0060] The thickness of the titanium oxide layer 9 is 1.0 nm or more. When the thickness of the titanium oxide layer 9 is within this range, leakage current caused by defects in the titanium oxide layer 9 is less likely to occur, and the output characteristics of the organic thin-film solar cell 1 using the laminate 7 are excellent.

[0061] Considering the reason for even more excellent output characteristics, the thickness of the titanium oxide layer 9 is preferably 2.0 nm or more, more preferably 3.0 nm or more, and still more preferably 4.0 nm or more.

[0062] On the other hand, the thickness of the titanium oxide layer 9 is 200.0 nm or less. When the thickness of the titanium oxide layer 9 is within this range, an increase in resistance is suppressed, and the output characteristics of the organic thin-film solar cell 1 are excellent. In addition, the titanium oxide layer 9 also has excellent transmittance. Furthermore, the energization time described later can be shortened, and the productivity of the laminate 7 is also excellent.

[0063] Considering the reasons for even more excellent output characteristics, transmittance, and productivity, the thickness of the titanium oxide layer 9 is preferably 100.0 nm or less, more preferably 50.0 nm or less, and still more preferably 30.0 nm or less.

[0064] The thickness of the titanium oxide layer 9 is determined as follows.

[0065] First, for any part of the titanium oxide layer 9, using an X-ray photoelectron spectroscopy apparatus (XPS apparatus), narrow-range photoelectron spectroscopy of Ti3s and In3d and sputtering based on argon ions (Ar + ) are repeatedly performed under the following conditions. Thus, the elemental composition ratio (unit: atomic %) in the sputtering depth direction in the titanium oxide layer 9 is obtained. When obtaining the elemental composition ratio, the relative sensitivity coefficient method is used. As the relative sensitivity coefficients for the peak areas of the narrow-range photoelectron spectroscopy, Ti3s: 0.150 and In3d: 4.530 are used respectively. The depth position from the outermost surface of the titanium oxide layer 9, which is the measurement start position, to the value where the elemental composition ratio of titanium (Ti) reaches 1 / 10 of the maximum value is set as the thickness of the titanium oxide layer 9.

[0066] (Conditions for measurement using the XPS apparatus)

[0067] ■ XPS apparatus: Quantera SXM (manufactured by ULVAC-PHI Inc.)

[0068] ■ X-ray source: Monochromatized Al-Kα ray (voltage: 15 kV, output: 25.0 W)

[0069] ■ X-ray beam diameter: 100 μm φ

[0070] ■ Measurement area: 100 μm φ

[0071] ■ Narrow region photoelectron spectroscopy measurement pass energy: 140 eV

[0072] ■ Narrow region photoelectron spectroscopy measurement energy step: 0.125 eV

[0073] ■ Sputtering rate: 5.4 nm / min (in terms of SiO2 conversion)

[0074] ■ Ar + Acceleration energy: 1 keV

[0075] ● Charge neutralization: Electron beam + Ar +

[0076] ■ Photoelectron extraction angle: 45° with respect to the normal direction of the sample surface (X-ray incident angle is the normal direction of the sample surface)

[0077] 《Atomic ratio (InOx / Ti)》

[0078] The titanium oxide layer 9 contains indium oxide.

[0079] In addition, when the content of titanium element is set as "Ti" and the content of indium oxide is set as "InOx", the atomic ratio (InOx / Ti) of the titanium oxide layer 9 is 0.50 or more and 20.00 or less.

[0080] Such a titanium oxide layer 9 is obtained by the method described later. However, in this case, it is considered that there are a large number of In 3+ , and a large number of oxygen defects are introduced. In addition, excessive electrons are generated due to the oxygen defects, and a part of them contributes to the conductivity as carriers.

[0081] Thus, the output characteristics of the organic thin film solar cell 1 using the laminate 7 having the titanium oxide layer 9 are excellent.

[0082] However, even mechanisms other than the above are within the scope of the present invention.

[0083] Considering the reason for more excellent output characteristics, the atomic ratio (InOx / Ti) is preferably 5.00 or more, more preferably 8.00 or more, further preferably greater than 10.00, and particularly preferably 11.00 or more.

[0084] On the other hand, regarding the upper limit, the atomic ratio (InOx / Ti) is preferably 18.00 or less, more preferably 16.00 or less, and further preferably 14.00 or less.

[0085] "Atomic Ratio (InM / Ti)"

[0086] The titanium oxide layer 9 further contains indium metal.

[0087] In addition, when the content of titanium element is set as "Ti" and the content of indium metal is set as "InM", the atomic ratio (InM / Ti) is less than 0.100. Thus, the titanium oxide layer 9 (electron transport layer 3) has excellent transmittance.

[0088] Considering the reason for more excellent transmittance, the atomic ratio (InM / Ti) is preferably 0.050 or less, more preferably 0.030 or less, and still more preferably 0.010 or less.

[0089] On the other hand, regarding the lower limit, the atomic ratio (InM / Ti) is preferably 0.001 or more.

[0090] The atomic ratio (InOx / Ti) and the atomic ratio (InM / Ti) are obtained as follows.

[0091] First, for the titanium oxide layer 9, measurement using an XPS apparatus is performed in the same manner as the above method. Next, the obtained narrow region photoelectron spectrum of In3d is peak-separated into an oxide component and a metal component. More specifically, in the peak separation, MultiPak (Ver.8.2C) is used as software for function fitting.

[0092] For the oxide, a Gaussian Lorentz function is applied. For the metal component, an asymmetric function (Tail Length: 14.85 ± 3.00, Tail Scale: 0.23 ± 0.10) is used.

[0093] It should be noted that the peak positions of indium oxide and indium metal are close to each other. Therefore, within the following range, with the peak height, full width at half maximum, and Gaussian function ratio as variable parameters, a convergence calculation is performed to minimize the sum of squared residuals from the measured spectrum.

[0094] ■ Indium Oxide: 444.6 ± 0.5 eV

[0095] ■ Indium Metal: 443.8 ± 0.5 eV

[0096] The elemental composition ratios (unit: atomic %) of titanium (Ti), indium oxide, and indium metal are integrated from the outermost surface of the titanium oxide layer 9 to the depth position where the elemental composition ratio of titanium (Ti) reaches 1 / 10 of the maximum value, and an integrated value is obtained.

[0097] Divide the integrated value of indium oxide (InOx) and the integrated value of metallic indium (InM) by the integrated value of titanium (Ti), respectively. Thereby, the atomic ratio (InOx / Ti) and the atomic ratio (InM / Ti) are obtained.

[0098] [Method for manufacturing a laminate]

[0099] In order to manufacture the above laminate 7, in a treatment liquid containing a Ti component, the member 8 is cathodically polarized, and then, the member 8 is anodically polarized. It should be noted that, as a counter electrode, an insoluble electrode such as a platinum electrode is suitable. The cathodic polarization and anodic polarization of the member 8 are carried out, for example, in an electrolytic treatment tank described later.

[0100] More specifically, first, the member 8 such as an ITO film is energized as a cathode. Thereby, a titanium oxide layer 9 is formed on the member 8. It is presumed that with this cathodic polarization, metallic indium is precipitated inside the titanium oxide layer 9 and at the interface between the titanium oxide layer 9 and the member 8 such as an ITO film.

[0101] It should be noted that it is presumed that the titanium oxide layer 9 is formed in the following manner. First, on the surface of the member 8, the pH rises with the generation of hydrogen. As a result, for example, when the Ti component in the treatment liquid is hexafluorotitanic acid and / or its salt, the hexafluorotitanate ions in the treatment liquid undergo defluorination, and at the same time, titanium hydroxide is generated. It is considered that this titanium hydroxide adheres to the surface of the member 8 and forms the titanium oxide layer 9 through dehydration condensation caused by subsequent cleaning, drying, etc. However, even if the mechanism is other than the above, it is within the scope of the present invention.

[0102] Next, the member 8 is energized as an anode. Thereby, the metallic indium precipitated in the titanium oxide layer 9 is oxidized, and the transmittance is improved.

[0103] As described above, the member 8 is preferably a conductive member, for example, a film of a conductive metal oxide such as an ITO film.

[0104] As described above, the member 8 can be disposed on a transparent substrate such as a glass substrate or a resin film. In this case, the transparent substrate with the member 8 (for example, a glass substrate with an ITO film) is cathodically polarized and then anodically polarized. In this case, the obtained laminate further has this transparent substrate.

[0105] The treatment liquid contains a Ti component (Ti compound) for supplying Ti (titanium element) to the formed titanium oxide layer 9.

[0106] As the Ti component, it is preferably at least one selected from the group consisting of hexafluorotitanic acid (H2TiF6), potassium hexafluorotitanate (K2TiF6), sodium hexafluorotitanate (Na2TiF6), ammonium hexafluorotitanate ((NH4)2TiF6), ammonium oxotitanium(IV) oxalate ((NH4)2[TiO(C2O4)2]), potassium oxotitanium(IV) oxalate dihydrate (K2[TiO(C2O4)2]·2H2O), titanium(IV) sulfate (Ti(SO4)2), and titanium(II) lactate (Ti(OH)2[OCH(CH3)COOH]2).

[0107] Among these, from the viewpoints of the stability of the treatment liquid and the ease of acquisition, etc., hexafluorotitanic acid and / or its salts (potassium hexafluorotitanate, sodium hexafluorotitanate, ammonium hexafluorotitanate) are preferred.

[0108] The Ti content in the treatment liquid is preferably 0.004 mol / L or more, more preferably 0.010 mol / L or more, and further preferably 0.020 mol / L or more.

[0109] On the other hand, the Ti content in the treatment liquid is preferably 1.300 mol / L or less, more preferably 1.000 mol / L or less, further preferably 0.700 mol / L or less, particularly preferably 0.300 mol / L or less, and most preferably 0.150 mol / L or less.

[0110] As the solvent of the treatment liquid, water can be used.

[0111] The pH of the treatment liquid is not particularly limited, for example, it is pH 2.0 to 5.0. The adjustment of pH can use known acid components (such as phosphoric acid, sulfuric acid, etc.) or base components (such as sodium hydroxide, ammonia water, etc.).

[0112] In the treatment liquid, surfactants such as sodium lauryl sulfate and alkynediol can be contained as needed. From the viewpoint of the temporal stability of the adhesion behavior, condensed phosphates such as pyrophosphates can be contained in the treatment liquid.

[0113] The liquid temperature of the treatment liquid is preferably 20 to 80°C, more preferably 40 to 60°C.

[0114] The treatment liquid can further contain a conduction aid.

[0115] Examples of the conduction aid include: sulfates such as potassium sulfate, sodium sulfate, magnesium sulfate, and calcium sulfate; nitrates such as potassium nitrate, sodium nitrate, magnesium nitrate, and calcium nitrate; chlorides such as potassium chloride, sodium chloride, magnesium chloride, and calcium chloride; etc.

[0116] The content of the conduction aid in the treatment liquid is preferably 0.010 to 1.000 mol / L, more preferably 0.020 to 0.500 mol / L.

[0117] When implementing cathodic polarization, the current density is preferably 0.01 A / dm 2 or more, more preferably 0.10 A / dm 2 or more, still more preferably 0.20 A / dm 2 or more.

[0118] On the other hand, when implementing cathodic polarization, the current density is preferably 5.00 A / dm 2 or less, more preferably 4.00 A / dm 2 or less, still more preferably 3.00 A / dm 2 or less.

[0119] Regarding the energization time, it can be appropriately set in order to obtain the desired thickness of the titanium oxide layer 9.

[0120] When implementing anodic polarization, the current density is preferably 0.01 A / dm 2 or more, more preferably 0.10 A / dm 2 or more, still more preferably 0.20 A / dm 2 or more.

[0121] On the other hand, when implementing anodic polarization, the current density is preferably 5.00 A / dm 2 or less, more preferably 4.00 A / dm 2 or less, still more preferably 3.00 A / dm 2 or less.

[0122] Regarding the energization time, it can be appropriately set in order to oxidize the indium metal deposited inside the titanium oxide layer 9 (In → In 3+ ).

[0123] After cathodic polarization and / or anodic polarization, water washing can be carried out.

[0124] The method of water washing is not particularly limited, and examples thereof include a method of immersing in water after cathodic polarization and / or anodic polarization. Water washing is carried out, for example, in a water washing tank described later. The temperature of the water (water temperature) used in water washing is preferably 40 to 90°C.

[0125] The water washing time is preferably more than 0.5 seconds, and preferably 1.0 to 5.0 seconds.

[0126] In addition, drying can be carried out instead of water washing, or drying can be carried out after water washing. The temperature and method during drying are not particularly limited. For example, a common drying method using a dryer or an electric furnace can be applied. The drying temperature is preferably 100°C or less.

[0127] As a method for manufacturing the laminate 7, a batch type or a continuous type is preferred.

[0128] This method can be appropriately selected according to, for example, the type and shape of the transparent substrate (such as a glass substrate, resin film, etc.) provided with the member 8.

[0129] For example, when the member 8 is provided on a glass substrate (that is, when using a glass substrate with the member 8), an intermittent type is preferred.

[0130] In this case, for example, a cleaning treatment tank, an electrolytic treatment tank, and a water washing tank can be prepared, and the glass substrate with the member 8 is immersed in each tank for treatment.

[0131] Cathodic polarization and anodic polarization can be carried out in one electrolytic treatment tank, or can be carried out in two different electrolytic treatment tanks.

[0132] In addition, when the member 8 is provided on a resin film wound in a roll shape (that is, when using a resin film with the member 8), from the viewpoint of productivity, a continuous type is preferred.

[0133] In this case, for example, a cleaning treatment tank, an electrolytic treatment tank, a water washing tank, and a drying device are arranged between an unwinding tension reel and a winding tension reel, and rollers are appropriately set so that the resin film with the member 8 continuously passes through each tank.

[0134] Cathodic polarization and anodic polarization can be carried out in one electrolytic treatment tank, or can be carried out in two different electrolytic treatment tanks. In the latter case, a water washing tank can also be arranged between the two electrolytic treatment tanks.

[0135] [Manufacturing method of organic thin-film solar cell]

[0136] An organic thin-film solar cell 1 having a transparent electrode layer 2, an electron transport layer 3, an organic semiconductor layer 4, a hole transport layer 5, and a collector layer 6 in sequence is manufactured using the above laminate 7.

[0137] For example, layers forming the organic semiconductor layer 4, the hole transport layer 5, and the collector layer 6 are sequentially formed on the titanium oxide layer 9 in the laminate 7.

[0138] The organic semiconductor layer 4 is formed, for example, by spin-coating a solution in which P3HT and PCBM are dissolved on the titanium oxide layer 9 serving as the electron transport layer 3 and drying it. Examples of the solvent of the solution include 2,6-dichlorotoluene, chloroform, chlorobenzene, and mixtures of two or more of them.

[0139] The hole transport layer 5 is formed, for example, by spin-coating an aqueous dispersion of PEDOT / PSS on the organic semiconductor layer 4 and drying it.

[0140] The collector layer 6 is formed, for example, by vapor-depositing a metal such as Au on the hole transport layer 5.

[0141] The method for forming each layer is not limited to these methods, and conventionally known methods can be appropriately used.

[0142] Examples

[0143] Hereinafter, the present invention will be specifically described by way of examples. However, the present invention is not limited to the following examples.

[0144] <Preparation of a member to be a transparent electrode layer>

[0145] A glass substrate with an ITO (indium tin oxide) film laminated on one surface of a glass substrate (30 mm × 35 mm, thickness 0.7 mm, non-alkali glass) by sputtering was prepared (sheet resistance value: 10 Ω / sq, manufactured by Ideal Star Co., Ltd.). The thickness of the ITO film was 150 nm. This glass substrate with an ITO film was used as a transparent substrate with a member to be a transparent electrode layer.

[0146] <Fabrication of a laminate of a transparent electrode layer and an electron transport layer>

[0147] Using the prepared glass substrate with an ITO film (transparent substrate with a member to be a transparent electrode layer), a laminate of a transparent electrode layer and an electron transport layer was fabricated as follows.

[0148] First, a treatment solution (hereinafter simply referred to as "treatment solution") containing 0.040 mol / L of potassium hexafluorotitanate (K2TiF6) and 0.10 mol / L of potassium sulfate (K2SO4) and adjusted to pH 4.0 with potassium hydroxide was prepared.

[0149] Next, the prepared glass substrate with an ITO film was immersed in a cleaning solution obtained by diluting Semi-Clean M4 (manufactured by Yokohama Oil & Fat Co., Ltd.) 20 times with ion-exchanged water, and ultrasonic cleaning was performed for 10 minutes. Then, the glass substrate with an ITO film was taken out of the cleaning solution and immersed in ion-exchanged water, and ultrasonic cleaning was performed for 10 minutes.

[0150] The cleaned glass substrate with an ITO film was immersed in the prepared treatment solution (liquid temperature: 50 °C). In the treatment solution, the glass substrate with an ITO film was cathodically polarized under the conditions shown in Table 1 below, and then anodically polarized. Then, it was immersed in a water bath at 25 °C for 2.0 seconds, washed with water, and dried at room temperature using a blower. Thus, a titanium oxide layer to be an electron transport layer was formed on the ITO film of the glass substrate with an ITO film. In this way, a glass substrate with an ITO film having a titanium oxide layer formed thereon (a laminate of a transparent electrode layer and an electron transport layer) was fabricated.

[0151] <Fabrication of the Comparative Laminate>

[0152] First, 6.25 mmol of titanium tetraisopropoxide was added to 12.5 mL of 2-methoxyethanol and cooled in an ice bath for 10 minutes. Then, 12.5 mmol of acetylacetone was added and stirred in the ice bath for 10 minutes to obtain a mixed solution. The obtained mixed solution was heated at 80 °C for 2 hours and then refluxed for 1 hour. Finally, the mixed solution was cooled to room temperature to obtain a titanium oxide precursor solution. The atmosphere for each process was set to a nitrogen atmosphere.

[0153] Next, the titanium oxide precursor solution was spin-coated on the ITO film of the cleaned glass substrate with an ITO film under the conditions of a rotation speed of 2000 rpm and a rotation time of 60 seconds to form a coating film. Then, it was left in the air to hydrolyze the titanium oxide precursor in the coating film. Subsequently, a heat treatment was performed at 150 °C for 1 hour to obtain a titanium oxide layer with a thickness of 30 nm.

[0154] The laminate (comparative laminate) fabricated in this way was used for No. 9 described later.

[0155] <Thickness and Atomic Ratio of the Titanium Oxide Layer>

[0156] According to the above method, the thickness, atomic ratio (InOx / Ti), and atomic ratio (InM / Ti) of the titanium oxide layer were determined. The results are shown in Table 1 below.

[0157] <Visible Light Transmittance of the Laminate>

[0158] The visible light transmittance (unit: %) of the fabricated laminate was measured under the following conditions. The results are shown in Table 1 below. The larger the value of the visible light transmittance, the better the transmittance can be evaluated.

[0159] ■ Measuring device: Spectrophotometer SD7000 (manufactured by Nippon Denshoku Industries Co., Ltd.)

[0160] ■ Measuring area: 5 mmφ

[0161] ■ Measuring wavelength: 600 nm

[0162] <Fabrication of the Organic Thin-Film Solar Cell>

[0163] Using the fabricated laminate, an organic thin-film solar cell with a photoelectric conversion area of 4 mm × 25 mm, i.e., 1.0 cm 2 was fabricated in the following manner.

[0164] <Formation of the Organic Semiconductor Layer>

[0165] Mix 2,6-dichlorotoluene and chloroform at a volume ratio of 1:1 to obtain a mixed solution. Dissolve P3HT (manufactured by Aldrich) and PCBM (manufactured by Frontier Carbon) in this mixed solution at a mass ratio of 5:4 so that the total concentration reaches 3.9% by mass.

[0166] Spin-coat the above mixed solution onto the titanium oxide layer at 1500 rpm for 60 seconds, and dry it at room temperature for about 10 minutes to form an organic semiconductor layer with a thickness of 250 nm.

[0167] "Formation of Hole Transport Layer"

[0168] Prepare a non-ionic surfactant (manufactured by Aldrich) containing 1% by mass of polyoxyethylene tridecyl ether (C 13 H 27 (OCH2CH2)6OH), 1% by mass of xylene, and using water and isopropyl alcohol as solvents. Mix 0.5 part by mass of this non-ionic surfactant with 100 parts by mass of 1.3% PEDOT / PSS aqueous dispersion (manufactured by Aldrich) to prepare a PEDOT / PSS aqueous dispersion containing PTE.

[0169] Heat the PEDOT / PSS aqueous dispersion containing PTE to 50 - 90 °C, spin-coat it onto the organic semiconductor layer at 6000 rpm for 60 seconds, and dry it naturally at room temperature to form a hole transport layer with a thickness of 80 nm.

[0170] "Formation of Collector Layer"

[0171] Vacuum-evaporate an Au electrode layer (collector layer) onto the hole transport layer to a thickness of about 100 nm.

[0172] More specifically, place a shadow mask corresponding to an electrode shape of 4 mm × 25 mm and a glass substrate formed up to the hole transport layer in the chamber. Use a rotary pump and a turbo molecular pump to evacuate the chamber so that the pressure in the chamber is 2 × 10 -3 Pa or less. Resistively heat a gold wire in this chamber, and deposit 100 nm of gold on the hole transport layer through the shadow mask. Set the film deposition rate to 10 - 15 nm / minute, and the pressure during film deposition to 1 × 10 -2 Pa or less.

[0173] Heat the glass substrate thus obtained, which has an ITO film (transparent conductive electrode layer), a titanium oxide layer (electron transport layer), an organic semiconductor layer, a hole transport layer, and a collector layer formed on one surface, at 150 °C for 5 minutes, and further hold it at 70 °C for 1 hour. Then, perform sealing in the atmosphere. Thus, an organic thin-film solar cell is fabricated.

[0174] <Evaluation (Output Characteristics) of Organic Thin-Film Solar Cells>

[0175] The fabricated organic thin-film solar cells were evaluated as follows.

[0176] Using a solar simulator light source device (manufactured by SAN-EI Electric, XES-502S), simulated sunlight with a spectral distribution of AM1.5G (IEC standard 60904-3) and a light intensity of 100 mW / cm 2 was irradiated onto the organic thin-film solar cells from the ITO film side. In this state, using a linear sweep voltammetry (LSV) measurement device (manufactured by Hokuto Denko, HZ-5000), the photocurrent-voltage curve of the organic thin-film solar cells was measured. The maximum output was obtained from the resulting curve and evaluated according to the following criteria. The results are shown in Table 1 below. The larger the value of the maximum output, the better the output characteristics can be evaluated.

[0177] A: The maximum output is 2.40 mW / cm 2 or more

[0178] B: The maximum output is 1.70 mW / cm 2 or more and less than 2.40 mW / cm 2

[0179] C: The maximum output is less than 1.70 mW / cm 2

[0180] [Table 1]

[0181]

[0182] <Summary of Evaluation Results>

[0183] As shown in Table 1 above, Nos. 1 to 7 with an atomic ratio (InOx / Ti) of 0.50 or more and 20.00 or less had better output characteristics than No. 9 that did not satisfy this condition.

[0184] Comparing Nos. 1 to 7, Nos. 1 and 6 with a larger atomic ratio (InOx / Ti) value than Nos. 2 to 5 and No. 7 had better output characteristics.

[0185] In addition, Nos. 1 to 7 with an atomic ratio (InM / Ti) less than 0.100 had a larger visible light transmittance value and better transmittance than No. 8 that did not satisfy this condition.

[0186] Therefore, both the output characteristics and transmittance of Nos. 1 to 7 were good.

[0187] Symbol Explanation

[0188] 1: Organic thin-film solar cell

[0189] 2: Transparent electrode layer

[0190] 3: Electron transport layer

[0191] 4: Organic semiconductor layer

[0192] 5: Hole transport layer

[0193] 6: Collector layer

[0194] 7: Laminate

[0195] 8: Component that becomes the transparent electrode layer

[0196] 9: Titanium oxide layer

Claims

1. A laminate which is a laminate of the transparent electrode layer and the electron transport layer of an organic thin film solar cell that sequentially includes a transparent electrode layer, an electron transport layer, an organic semiconductor layer, a hole transport layer, and a collector layer, wherein it has: a member that forms the transparent electrode layer; and a titanium oxide layer that is disposed on the member that forms the transparent electrode layer and forms the electron transport layer, the thickness of the titanium oxide layer is 1.0 nm or more and 200.0 nm or less, the titanium oxide layer contains indium oxide and metallic indium, and when the content of titanium element is Ti, the content of indium oxide is InOx, and the content of metallic indium is InM, InOx / Ti is 0.50 or more and 20.00 or less in atomic ratio, and InM / Ti is 0.001 or more and less than 0.100 in atomic ratio.

2. An organic thin film solar cell that sequentially includes a transparent electrode layer, an electron transport layer, an organic semiconductor layer, a hole transport layer, and a collector layer, which uses the laminate according to claim 1.

3. A method for manufacturing a laminate, which is a method for manufacturing the laminate according to claim 1, wherein, In a treatment liquid containing a Ti component, the member that forms the transparent electrode layer is cathodically polarized and then anodically polarized, whereby the titanium oxide layer is formed on the member that forms the transparent electrode layer.

4. The manufacturing method of the laminate according to claim 3, wherein, The Ti content in the treatment liquid is 0.004 mol / L or more and 1.300 mol / L or less.

5. The method for manufacturing a laminate according to claim 3 or 4, wherein, The Ti component is at least one selected from the group consisting of hexafluorotitanic acid, potassium hexafluorotitanate, sodium hexafluorotitanate, ammonium hexafluorotitanate, ammonium oxotitanium oxalate, potassium oxotitanium oxalate dihydrate, titanium sulfate, and titanium lactate.

6. The method for manufacturing a laminate according to claim 3 or 4, wherein, The component that will become the light-transmissive electrode layer is used as the cathode, and energization is carried out at a current density of 0.01 A / dm 2 or more and 5.00 A / dm 2 or less. Then, the component that will become the light-transmissive electrode layer is used as the anode, and energization is carried out at a current density of 0.01 A / dm 2 or more and 5.00 A / dm 2 or less.

7. The method for manufacturing a laminate according to claim 5, wherein, The member that will become the light-transmissive electrode layer is used as the cathode, and is energized at a current density of 0.01 A / dm 2 or more and 5.00 A / dm 2 or less. Then, the member that will become the light-transmissive electrode layer is used as the anode, and is energized at a current density of 0.01 A / dm 2 or more and 5.00 A / dm 2 or less.

8. A method for manufacturing an organic thin-film solar cell, wherein, Use the laminate according to claim 1 to manufacture an organic thin film solar cell that sequentially includes a transparent electrode layer, an electron transport layer, an organic semiconductor layer, a hole transport layer, and a collector layer.

Images