Manufacturing method for organic thin-film solar cells

Abstract

To provide a method for manufacturing an organic thin-film solar cell using bonding.SOLUTION: A method for manufacturing an organic thin film solar cell comprises: a first laminating process of preparing a first laminate 10 in which a first electrode 2 and an organic active layer 3 are laminated in sequence on a substrate 1; a second laminating process of preparing a second laminate 20 in which a second electrode 7 is laminated on a coating layer 8; and a bonding process of bonding the organic active layer 3 of the first laminate 10 and the second electrode 7 of the second laminate 20 by thermocompression bonding.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a method for producing an organic thin-film solar cell. By law Regarding. [Background technology]

[0002] Organic thin-film solar cells are attracting attention because there are fewer restrictions on where they can be installed and it is said to be relatively easy to enlarge the elements.

[0003] An organic thin-film solar cell is obtained by sequentially stacking a first electrode, an organic active layer, and a second electrode. Each layer of the organic thin-film solar cell is formed by, for example, a dry process such as a vacuum deposition method, a sputtering method, an ion plating method, or a chemical vapor deposition method, or a wet process in which a dispersion liquid is applied.

[0004] For example, Patent Document 1 describes a method for producing a second electrode by a wet process. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2014-236064 A Summary of the Invention [Problem to be solved by the invention]

[0006] The organic active layer in an organic thin-film solar cell is easily damaged by heat and solvents. For example, when an electrode is evaporated onto the organic active layer, the organic active layer is damaged by the heat during evaporation. Also, when an electrode is applied onto the organic active layer by a wet process, the organic active layer is damaged by the solvent contained in the coating solution.

[0007] The present invention has been made in view of the above problems, and has an object to provide a method for manufacturing an organic thin-film solar cell using bonding. [Means for solving the problem]

[0008] In order to solve the above problems, the present invention provides the following means.

[0009] (1) A method for producing an organic thin-film solar cell according to a first aspect includes a first lamination step of preparing a first laminate in which a first electrode and an organic active layer are laminated in that order on a substrate; a second lamination step of preparing a second laminate in which a second electrode is laminated on a coating layer; and a bonding step of bonding the organic active layer of the first laminate and the second electrode of the second laminate by thermocompression bonding.

[0010] (2) In the method for producing an organic thin-film solar cell according to the above aspect, the covering layer may be a hot-melt sheet having a melting point or a glass transition point lower than that of the organic active layer.

[0011] (3) In the method for producing an organic thin-film solar cell according to the above aspect, the second electrode may have a thickness of 20 nm or more and 150 nm or less.

[0012] (4) In the method for producing an organic thin-film solar cell according to the above aspect, the temperature of the thermocompression bonding may be lower than the melting point or the glass transition point of the organic active layer and higher than the melting point or the glass transition point of the coating layer.

[0013] (5) In the method for producing an organic thin-film solar cell according to the above aspect, the pressure of the thermocompression bonding is 80 g / cm 2 More than 650g / cm 2 It may be the following.

[0014] (6) The method for producing an organic thin-film solar cell according to the above aspect may further include a step of surface-modifying the second electrode with a modifying material having a sulfide group, a disulfide group, or a thiol group, prior to the bonding step.

[0015] (7) An organic thin-film solar cell according to a second aspect comprises a first electrode, an organic active layer, a second electrode, and a coating layer, in that order, and a first surface of the second electrode facing the coating layer has a glossiness of 30 or more and 35 or less, measured at an incident angle of 60° as specified in JIS Z 8741.

[0016] (8) In the organic thin-film solar cell according to the above aspect, a second surface of the second electrode opposite to the first surface may have a glossiness of 60 or more and 65 or less when measured at an incident angle of 60° as defined in JIS Z 8741.

[0017] (9) In the organic thin-film solar cell according to the above aspect, a second surface of the second electrode opposite to the first surface may be modified with a modifying material having a sulfide group, a disulfide group, or a thiol group.

[0018] (10) In the organic thin-film solar cell according to the above aspect, the surface of the first electrode facing the organic active layer may be modified with a modifying material having a silyl ether group, a carboxylic acid group, or a phosphonic acid group. Effect of the Invention

[0019] The method for manufacturing an organic thin-film solar cell according to this embodiment can reduce damage to the organic active layer. [Brief description of the drawings]

[0020] [Figure 1] 1 is a perspective view of an organic thin-film solar cell according to a first embodiment. [Diagram 2] FIG. 2 is a perspective view illustrating a first lamination step of the manufacturing method for the organic thin-film solar cell according to the first embodiment. [Diagram 3] FIG. 4 is a perspective view illustrating a second lamination step in the manufacturing method for the organic thin-film solar cell according to the first embodiment. [Figure 4] FIG. 2 is a perspective view illustrating a bonding step in the manufacturing method for the organic thin-film solar cell according to the first embodiment. [Diagram 5] 1A and 1B are a perspective view and an enlarged view of a characteristic portion of an organic thin-film solar cell according to a second embodiment. [Figure 6] 11A and 11B are a perspective view and an enlarged view of a characteristic portion of an organic thin-film solar cell according to a third embodiment. [Figure 7] 1 shows current-voltage curves (JV curves) of the organic thin-film solar cells of Example 1, Example 2, and Comparative Example 1. [Figure 8] 1 shows the change in energy conversion efficiency with irradiation time of the organic thin-film solar cells of Examples 1, 3, and 4. [Figure 9] 1 shows the change in energy conversion efficiency with irradiation time of the organic thin-film solar cells of Examples 1, 5, and 6. [Figure 10] 1 shows the change in energy conversion efficiency with irradiation time of the organic thin-film solar cells of Examples 1, 7, and 8. [Figure 11] 1 shows a current-voltage curve (JV curve) of the organic thin-film solar cell of Example 9. [Figure 12] 1 shows the change in energy conversion efficiency of the organic thin-film solar cell of Example 9 as a function of irradiation time. [Figure 13] 1 shows current-voltage curves (JV curves) of the organic thin-film solar cells of Examples 9 and 10. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] The present embodiment will be described in detail below. The following description is an example of the present invention, and the present invention is not limited thereto, and can be appropriately modified and implemented without departing from the gist of the present invention.

[0022] "First embodiment" 1 is a perspective view of an organic thin-film solar cell according to the first embodiment. The organic thin-film solar cell 1000 includes, for example, a substrate 1, a first electrode 2, an organic active layer 3, a second electrode 7, and a covering layer 8. On the substrate 1, the first electrode 2, the organic active layer 3, the second electrode 7, and the covering layer 8 are laminated in this order.

[0023] The substrate 1 is not particularly limited as long as it supports a structure. The substrate 1 preferably has excellent light transmittance. The substrate 1 has, for example, a visible light transmittance of 90% or more. The substrate 1 is also preferably flexible. The substrate 1 is, for example, glass, a plastic film, or the like. For example, polyethylene terephthalate, polyethylene naphthalate, or the like can be used as a resin constituting the plastic film.

[0024] The first electrode 2 is, for example, a transparent electrode. The first electrode 2 is on the substrate 1. A known electrode can be used as the first electrode 2. The first electrode 2 is, for example, indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide, tin oxide, titanium oxide, graphene, or the like.

[0025] The organic active layer 3 is a layer including an organic semiconductor. The organic active layer 3 is sandwiched between a first electrode 2 and a second electrode 7. The organic active layer 3 has, for example, an electron collecting layer 4, a power generating layer 5, and a hole collecting layer 6. The electron collecting layer 4 and the hole collecting layer 6 sandwich the power generating layer 5. The electron collecting layer 4 is, for example, on the first electrode 2 side of the power generating layer 5. The hole collecting layer 6 is, for example, on the second electrode 7 side of the power generating layer 5. The positional relationship between the electron collecting layer 4 and the hole collecting layer 6 may be reversed depending on the energy levels of the first electrode 2 and the second electrode 7. For example, when the second electrode 7 is gold, the relationship shown in FIG. 1 is satisfied, but when the second electrode 7 is aluminum, the positional relationship between the electron collecting layer 4 and the hole collecting layer 6 is reversed. The electron collecting layer 4 may be called an electron transport layer, and the hole collecting layer 6 may be called a hole transport layer.

[0026] The power generation layer 5 is a layer that receives light and generates electricity. The power generation layer 5 includes a donor and an acceptor. The power generation layer 5 may be a layer in which the donor and the acceptor are mixed (bulk heterostructure), or may be a layer in which a donor layer and an acceptor layer are stacked (stacked structure). The donor absorbs light and becomes excited. The excited exciton moves to the interface between the donor and the acceptor. When the exciton transfers an electron to the acceptor, the donor generates a cation (hole), and the acceptor generates an anion. The cations and anions flow toward different electrodes, causing a current to flow in an external circuit.

[0027] The donor is, for example, a p-type organic semiconductor. A known donor can be used. The donor can be, for example, a conjugated polymer, a phthalocyanine derivative, a porphyrin derivative, a triarylamine derivative, a carbazole derivative, an oligothiophene derivative, or the like. For example, poly(3-hexylthiophene-2,5-diyl) (P3HT) is a conjugated polymer and is used as the donor.

[0028] The acceptor is, for example, an n-type organic semiconductor. The acceptor may be a known one, and may be a non-fullerene-based compound or a fullerene-based compound. The acceptor of the fullerene-based compound is, for example,

[60] PCBM, bis-

[60] PCBM,

[70] PCBM, bis-

[70] PCBM, etc. In addition, a fullerene derivative having a silylmethyl group (SIMEF) is also an example of the acceptor of the fullerene-based compound. The acceptor of the non-fullerene-based compound is, for example, a TTBT-based compound, an ITIC-based compound, an IDT-based compound, an IDTT-based compound, a TTCTT-based compound, PPhTQ, ​​etc.

[0029] The electron collecting layer 4 is a layer that collects electrons in order to efficiently transport the electrons generated in the power generation layer 5 toward the first electrode 2. The electron collecting layer 4 may be made of a known material. The electron collecting layer 4 may be made of, for example, a metal oxide or a metal nitride. Examples of oxides used in the electron collecting layer 4 include titanium oxide, zinc oxide, silicon oxide, tin oxide, tungsten oxide, tantalum oxide, barium titanate, barium zirconate, zirconium oxide, hafnium oxide, aluminum oxide, yttrium oxide, and zirconium silicate. Examples of nitrides used in the electron collecting layer 4 include silicon nitride. Other examples of the electron collecting layer 4 that may be used include cadmium sulfide, zinc selenide, zinc sulfide, and cadmium telluride.

[0030] The hole-collecting layer 6 is a layer that collects holes in order to efficiently transport electrons generated in the power generation layer 5 toward the second electrode 7. A known material can be used for the hole-collecting layer 6. The hole-collecting layer 6 is, for example, PEDOT:PSS (a composite of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS)).

[0031] The second electrode 7 is a material having electrical conductivity. The second electrode 7 is on the organic active layer 3. The second electrode 7 is, for example, a metal such as gold, silver, or aluminum, or an organic conductive ink such as PEDOT:PSS.

[0032] When the second electrode 7 is a metal, the second surface 7B of the second electrode 7 is glossier than the first surface 7A. This configuration results from the manufacturing method described below. The first surface 7A is the surface of the second electrode 7 facing the coating layer 8, and the second surface 7B is the surface of the second electrode 7 facing the organic active layer 3.

[0033] The second surface 7B is a glossy surface. The second surface 7B has a glossiness due to the (111) plane being mainly exposed. "The (111) plane is mainly exposed" means that, when the crystal plane is measured at 10 different arbitrary measurement points, 50% or more of the second surface 7B is oriented in the (111) direction. The glossiness of the second surface 7B is 60 or more and 65 or less. The glossiness is a value measured at an incident angle of 60° in accordance with the JIS Z 8741 standard. The glossiness can be measured, for example, with a gloss meter (GC-1, UGV-6P) manufactured by Suga Test Instruments Co., Ltd.

[0034] The first surface 7A is a non-glossy surface and looks duller than the second surface 7B. The first surface 7A has no exposed (111) plane. The gloss of the first surface 7A is 30 or more and 35 or less.

[0035] The thickness of the second electrode 7 is, for example, 20 nm or more and 150 nm or less. The thickness of the second electrode 7 is preferably 100 nm or less, and more preferably 30 nm or more and 60 nm or less. If the thickness of the second electrode 7 is sufficiently thin, the conformability of the second electrode 7 to the organic active layer 3 is improved in the bonding process described later.

[0036] The covering layer 8 is on the second electrode 7. The covering layer 8 prevents the intrusion of moisture and the like into the organic active layer 3, and also prevents the organic active layer 3 from being contaminated.

[0037] The covering layer 8 is a resin sheet. The covering layer 8 is, for example, a fluororesin or a polyester-based resin (for example, PET). The covering layer 8 is, for example, a hot melt sheet having a melting point or glass transition point lower than that of the organic active layer 3 (particularly the power generation layer 5). In the bonding step described below, the covering layer 8 melts by thermocompression bonding, thereby improving the conformability of the second electrode 7 to the organic active layer 3.

[0038] The covering layer 8 preferably has a Rockwell hardness (D-785) of R115 or less. When the covering layer 8 is sufficiently soft, the conformability of the covering layer 8 and the second electrode 7 to the organic active layer 3 is improved.

[0039] The thickness of the covering layer 8 is, for example, 100 μm or less, and preferably 50 μm or less. This thickness is the thickness after thermocompression bonding. When the covering layer 8 has sufficient flexibility, the conformability of the second electrode 7 to the organic active layer 3 is improved.

[0040] Next, a description will be given of a method for manufacturing the organic thin-film solar cell 100 according to the first embodiment. The method for manufacturing the organic thin-film solar cell 100 according to the first embodiment includes a first lamination step, a second lamination step, and a bonding step.

[0041] 2 is a schematic diagram for explaining the first lamination step. In the first lamination step, a first laminate 10 is prepared. The first laminate 10 is produced by laminating a first electrode 2 and an organic active layer 3 in this order on a substrate 1. The first electrode 2 can be formed by, for example, vacuum deposition or the like. The organic active layer 3 can be formed by, for example, coating. The first electrode 2 and the organic active layer 3 can be produced by a known method.

[0042] FIG. 3 is a schematic diagram for explaining the second lamination step. In the second lamination step, a second laminate 20 is prepared. The second laminate 20 is produced by forming a second electrode 7 on a coating layer 8. The second electrode 7 can be produced by, for example, vacuum deposition or coating. For example, the second electrode 7 can be produced by vacuum depositing gold on the coating layer 8. Alternatively, for example, the second electrode 7 can be produced by coating the coating layer 8 with silver paste diluted with 1,2-dimethoxyethane and baking it.

[0043] When the second electrode 7 is formed on the covering layer 8, the second surface 7B of the second electrode 7 is exposed. The second electrode 7 grows so that the (111) plane is exposed, and the second surface 7B becomes a glossy surface.

[0044] 4 is a schematic diagram for explaining the bonding step. In the bonding step, the first laminate 10 and the second laminate 20 are bonded together. The first laminate 10 and the second laminate 20 are bonded together such that the organic active layer 3 of the first laminate 10 and the second electrode 7 of the second laminate 20 face each other. The bonding is performed by thermocompression bonding.

[0045] Thermocompression bonding is performed, for example, at a temperature lower than the melting point or glass transition point of the organic active layer 3 (particularly the power generation layer 5). Thermocompression bonding is preferably performed at a temperature higher than the melting point or glass transition point of the coating layer 8. For example, the thermocompression bonding temperature is preferably 130° C. or higher and 180° C. or lower, and more preferably 140° C. or higher and 150° C. or lower. By performing thermocompression bonding in this temperature range, it is possible to ensure close contact between the first stack 10 and the second stack 20 and to suppress damage to the organic active layer 3.

[0046] The pressure for thermocompression is, for example, 80 g / cm 2 More than 650g / cm 2 The pressure for thermocompression is, for example, 80 g / cm 2 More than 325g / cm 2 The following is more preferable: If the pressure is too high, the performance of the organic thin-film solar cell 100 tends to decrease, and if the pressure is too low, the conformability of the second electrode 7 to the organic active layer 3 decreases.

[0047] The compression time of the thermocompression bonding is, for example, 1 minute or more. The compression time is preferably 3 minutes or more and 10 minutes or less, and more preferably 4 minutes or more and 6 minutes or less. If the compression time is short, the performance of the organic thin-film solar cell 100 tends to decrease, and if the compression time is long, the stability of the organic thin-film solar cell 100 tends to decrease.

[0048] By carrying out the thermocompression bonding, the second electrode 7 is closely attached to the surface of the organic active layer 3, and the organic thin-film solar cell 100 is obtained.

[0049] In the organic thin-film solar cell 100 according to the first embodiment, the second electrode 7 is not formed on the organic active layer 3, which reduces damage to the organic active layer 3. In addition, the organic thin-film solar cell 100 according to the first embodiment can be produced by a simple method of bonding.

[0050] "Second embodiment" 5 is a perspective view and an enlarged view of a characteristic portion of an organic thin-film solar cell 101 according to the second embodiment. The organic thin-film solar cell 101 according to the second embodiment differs from the organic thin-film solar cell 100 according to the first embodiment in that the second surface 7B of the second electrode 7 is modified with a modifying material. In the organic thin-film solar cell 101 according to the second embodiment, the same components as those in the organic thin-film solar cell 100 according to the first embodiment are denoted by the same reference numerals and will not be described.

[0051] The second surface 7B of the second electrode 7 is modified with a modifier. The modifier has a sulfide group, a disulfide group, or a thiol group. The modifier has a binding site at one end and a functional site at the other end. The sulfide group, the disulfide group, or the thiol group functions as a binding site. The binding site is, for example, chemically adsorbed on the surface of the second electrode 7 to form a self-assembled monolayer. When the second electrode 7 is made of gold and the second surface 7B is a (111) surface, the self-assembled monolayer is formed particularly uniformly. The modifier is, for example, pentafluorobenzenethiol (PFBT).

[0052] The organic thin-film solar cell 101 according to the second embodiment can be manufactured in the same manner as the organic thin-film solar cell 100 according to the first embodiment, except that the surface of the second electrode 7 is surface-modified before the bonding step. The manufacturing method of the organic thin-film solar cell 101 according to the second embodiment further includes a step of surface-modifying the second electrode 7 with a modifier having a sulfide group, a disulfide group, or a thiol group, before the bonding step.

[0053] The second surface 7B of the second electrode 7 is surface-modified after laminating the second laminate 20 and before the lamination process. When the second electrode 7 is vacuum-formed on the organic active layer 3, the surface cannot be covered with a modifier. The surface modification is performed, for example, by applying a solution containing a modifier to the second surface 7B of the second electrode 7. For example, the solvent of the solution is ethanol.

[0054] Thereafter, in a bonding process, the second electrode 7 and the organic active layer 3 are bonded together. The functional site of the modifier exposed on the second surface 7B of the second electrode 7 is bonded to the organic active layer 3. For example, pentafluorobenzenethiol (PFBT) has the effect of promoting hole injection.

[0055] In the organic thin-film solar cell 101 according to the second embodiment, the second electrode 7 is not formed on the organic active layer 3, and therefore damage to the organic active layer 3 can be reduced. Moreover, the organic thin-film solar cell 101 according to the second embodiment can be produced by a simple method of bonding. Furthermore, by surface-modifying the second surface 7B of the second electrode 7, the short-circuit current density and power conversion efficiency (PCE) of the organic thin-film solar cell 101 are improved.

[0056] "Third embodiment" 6 is a perspective view and an enlarged view of a characteristic portion of an organic thin-film solar cell 102 according to the third embodiment. The organic thin-film solar cell 102 according to the third embodiment differs from the organic thin-film solar cell 101 according to the second embodiment in that the first surface 2A of the first electrode 2 is modified with a modifying material. In the organic thin-film solar cell 102 according to the third embodiment, the same components as those in the organic thin-film solar cell 101 according to the second embodiment are denoted by the same reference numerals and will not be described.

[0057] A first surface 2A of the first electrode 2 is modified with a modifying material. The first surface 2A is the surface of the first electrode 2 on the organic active layer 3 side. The second surface 2B is the surface of the first electrode 2 on the substrate 1 side.

[0058] The modifying material that modifies the first surface 2A has a silyl ether group, a carboxylic acid group, or a phosphonic acid group. The modifying material has a binding site at one end and a functional site at the other end. The silyl ether group, the carboxylic acid group, or the phosphonic acid group functions as a binding site. When the binding site bonds with the first electrode 2, the modifying material becomes a self-assembled monolayer. For example, when the first electrode 2 is ITO, the titanium element of the first electrode 2 and the functional site of the modifying material bond. The modifying material is, for example, polyethyleneimine (PEIE) or triphenyl(4-sulfonatobutyl)phosphonium (TPPBS).

[0059] The organic thin-film solar cell 102 according to the third embodiment can be manufactured in the same manner as the organic thin-film solar cell 101 according to the second embodiment, except that the surface of the first electrode 2 is surface-modified before the organic active layer 3 is formed. The manufacturing method for the organic thin-film solar cell 102 according to the third embodiment further includes a step of surface-modifying the first electrode 2 with a modifier having a silyl ether group, a carboxylic acid group, or a phosphonic acid group before the organic active layer 3 is formed. The surface modification is performed, for example, by applying a solution containing the modifier to the first surface 2A of the first electrode 2.

[0060] In the organic thin-film solar cell 102 according to the third embodiment, the second electrode 7 is not formed on the organic active layer 3, and therefore damage to the organic active layer 3 can be reduced. Moreover, the organic thin-film solar cell 102 according to the third embodiment can be produced by a simple method of bonding. Furthermore, by surface-modifying the first surface 2A of the first electrode 2, the short-circuit current density and power conversion efficiency (PCE) of the organic thin-film solar cell 102 are improved.

[0061] Although the preferred embodiment of the present invention has been described in detail above, the present invention is not limited to the specific embodiment, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims. EXAMPLES

[0062] Example 1 First, a first laminate 10 was produced. The first laminate 10 was produced by sequentially laminating an electron collection layer 4, a power generation layer 5, and a hole collection layer 6 on a substrate 1 on which a commercially available first electrode 2 had been formed. The substrate 1 was made of glass. The first electrode 2 was made of ITO. The electron collection layer 4 was made of zinc oxide. The power generation layer 5 used poly(3-hexylthiophene-2,5-diyl) (P3HT) as the donor and

[60] PCBM as the acceptor. The power generation layer 5 has a bulk heterostructure.

[0063] Next, the second laminate 20 was prepared. The second laminate 20 was prepared by laminating the second electrode 7 on the covering layer 8. The covering layer 8 was made of Celer (registered trademark) F1550H (manufactured by Kureha Extron Co., Ltd.). The second electrode 7 was 5×10 -3 Gold was evaporated at a thickness of 20 Pa. The thickness of the second electrode 7 was set to 60 nm.

[0064] Next, the first laminate 10 and the second laminate 20 were thermally pressed together at 150° C. The pressing time was 5 minutes, and the pressure was 325 / cm 2 The first laminate 10 and the second laminate 20 were bonded together to produce an organic thin-film solar cell 100. The area of ​​the light-receiving surface of the organic thin-film solar cell 100 was 0.1 cm2. 2 It was decided.

[0065] The current-voltage curve (JV curve) of the fabricated organic thin-film solar cell 100 was measured. The current-voltage curve was measured using a 4262 multi-meter manufactured by ADC Corporation. The measurement results are shown in FIG.

[0066] The power conversion efficiency (PCE) was calculated from the current-voltage curve. The power conversion efficiency of Example 1 was 2.6%. PCE is expressed as the current density at the maximum output point in J max , voltage is V max The energy of the irradiated light is P inc Then, it can be obtained from the following formula: PCE(%)=(J max ×V max ) / P inc ×100

[0067] Example 2 Example 2 differs from Example 1 in that the second electrode 7 was made of silver prepared by coating. In Example 2, the second electrode 7 was prepared by coating a silver paste diluted with 1,2-dimethoxyethane onto the coating layer 8 and baking at 80° C. for 2 minutes.

[0068] For Example 2, the current-voltage curve was obtained and the power conversion efficiency (PCE) was calculated in the same manner as for Example 1. The measurement results are shown in Figure 7. The power conversion efficiency of Example 1 was 2.5%.

[0069] Comparative Example 1 Comparative Example 1 differs from Example 1 in that a first electrode 2, an electron collection layer 4, a power generation layer 5, a hole collection layer 6, a second electrode 7, and a coating layer 8 are laminated in this order on a substrate 1. The materials of each layer are the same as those in Example 1. The second electrode 7 was formed by forming a gold film on the hole collection layer 6 by vacuum deposition.

[0070] For Comparative Example 1, a current-voltage curve was obtained and a power conversion efficiency (PCE) was calculated in the same manner as in Example 1. The measurement results are shown in Figure 7. The power conversion efficiency of Comparative Example 1 was 3.0%.

[0071] The organic thin-film solar cells according to Examples 1 and 2 produced by lamination exhibited performance equivalent to that of Comparative Example 1 produced by sequential film formation. That is, even with the simple method of lamination, the same performance was exhibited as in the case of sequential film formation.

[0072] (Examples 3 and 4) Examples 3 and 4 differ from Example 1 in that the film thickness of the second electrode 7 was changed. In Example 3, the film thickness of the second electrode 7 was set to 30 nm. In Example 4, the film thickness of the second electrode 7 was set to 120 nm.

[0073] The time change in the energy conversion efficiency of the organic thin-film solar cells of Example 1, Example 3, and Example 4 was measured. The time change in the energy conversion efficiency was measured by applying a reference condition (AM1.5 global radiation spectrum, 100 mW cm -2 The results are shown in Figure 8.

[0074] Example 4, in which the second electrode 7 was thick, tended to have a lower energy conversion efficiency than Examples 1 and 3. This is believed to be because the thick second electrode 7 did not conform sufficiently to the surface of the organic active layer 3 in the bonding process, resulting in insufficient adhesion.

[0075] (Examples 5 and 6) Examples 5 and 6 differ from Example 1 in that the pressure bonding time in the lamination step was changed. In Example 5, the pressure bonding time was set to 3 minutes. In Example 6, the pressure bonding time was set to 10 minutes.

[0076] Similarly to the above, the change over time in the energy conversion efficiency was measured for the organic thin-film solar cells of Examples 1, 5, and 6. The results are shown in FIG.

[0077] Example 5, which had a short bonding time, tended to have a lower energy conversion efficiency than Example 1. This is believed to be due to insufficient adhesion between the second electrode 7 and the organic active layer 3 in the bonding process. Also, Example 6, which had a long bonding time, showed a faster decrease in energy conversion efficiency than Example 1.

[0078] (Examples 7 and 8) Examples 7 and 8 differ from Example 1 in that the pressure during the bonding process was changed. Example 7 had a pressure of 80 / cm 2 In Example 8, the compression pressure was 650 / cm 2 It was decided.

[0079] Then, in the same manner as above, the change over time in the energy conversion efficiency was measured for the organic thin-film solar cells of Examples 1, 7, and 8. The results are shown in FIG.

[0080] Example 7 had a higher initial energy conversion efficiency and a smaller rate of decrease in the energy conversion efficiency than Example 1. On the other hand, Example 8, which had a higher compression bonding pressure, had a larger change in the energy conversion efficiency over time.

[0081] Example 9 In Example 9, the area of ​​the light receiving surface of the organic thin-film solar cell was set to 1.0 cm 2 This differs from the first embodiment in that it is 10 times that of the first embodiment.

[0082] In Example 9, the current-voltage curve and the change over time in the energy conversion efficiency were measured in the same manner as described above. The current-voltage curve of Example 9 is shown in FIG. 12, which shows the change over time in the energy conversion efficiency of Example 9. The change over time in the energy conversion efficiency of Example 9 was measured over 100 hours. The energy conversion efficiency of Example 9 was 2.3%, which was equivalent to that of Example 1. Furthermore, the energy conversion efficiency of Example 9 after 100 hours was 98% of the maximum value, and the energy conversion efficiency was maintained.

[0083] Example 10 Example 10 differs from Example 9 in that the second surface 7B of the second electrode 7 was surface-modified. The surface modification was performed by applying ethanol containing pentafluorobenzenethiol to the surface of the second electrode 7 and leaving it for 5 minutes.

[0084] In Example 10, the current-voltage curve and energy conversion efficiency were measured in the same manner as above. The current-voltage curve and energy conversion efficiency of Example 10 are shown in FIG. 13. The energy conversion efficiency of Example 10 was 2.5%, which was improved compared to Example 9 in which the second surface 7B was not surface-modified. It is believed that by modifying the electrode, the short-circuit current density was improved, and as a result, the energy conversion efficiency was improved. [Explanation of symbols]

[0085] Reference Signs List 1...substrate, 2...first electrode, 3...organic active layer, 4...electron collection layer, 5...power generation layer, 6...hole collection layer, 7...second electrode, 8...covering layer, 10...first laminate, 20...second laminate, 2A, 7A...first surface, 2B, 7B...second surface, 100, 101, 102...organic thin-film solar cell

Claims

1. a first lamination step of preparing a first laminate in which a first electrode and an organic active layer are laminated in this order on a substrate; a second lamination step of preparing a second laminate by laminating a second electrode on the coating layer; a bonding step of bonding the organic active layer of the first stack and the second electrode of the second stack by thermocompression bonding; The method for producing an organic thin-film solar cell, wherein the pressure of the thermocompression bonding is 80 g / cm 2 or more and 650 g / cm 2 or less.

2. The method for producing an organic thin-film solar cell according to claim 1 , wherein the covering layer is a hot-melt sheet having a melting point or a glass transition point lower than that of the organic active layer.

3. The method for producing an organic thin-film solar cell according to claim 1 , wherein the second electrode has a thickness of 20 nm or more and 150 nm or less.

4. The method for producing an organic thin-film solar cell according to any one of claims 1 to 3, wherein a temperature of the thermocompression bonding is lower than a melting point or a glass transition point of the organic active layer and higher than a melting point or a glass transition point of the coating layer.

5. The method for producing an organic thin-film solar cell according to any one of claims 1 to 4, further comprising a step of surface-modifying the second electrode with a modifying material having a sulfide group, a disulfide group, or a thiol group prior to the bonding step.

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