JP2013016669A - Manufacturing method of photoelectric conversion element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture solar cells, inhibiting short-circuit faults, with a small number of processes at low cost.SOLUTION: A manufacturing method of solar cells includes the steps: forming an auxiliary metal wiring 26 on a support medium 10; burying an opening of the auxiliary metal wiring 26 with a transparent resin, formed by polymerizing a component containing a multifunctional (meta) acrylic monomer, and covering the auxiliary metal wiring to form a transparent insulation layer 30; performing etching on the transparent insulation layer 30 until at least a part of a surface of the auxiliary metal wiring 26 is exposed and a surface of the transparent insulation layer 30 in the opening becomes substantially the same flat surface as a surface of the auxiliary metal wiring 26; forming a lower electrode layer 12 on surfaces of the transparent insulation layer 30 and the auxiliary metal wiring 26; and sequentially forming a photoelectric conversion layer 15 and an upper electrode 21 on the lower electrode layer 12.

Description

  The present invention relates to a method for producing an organic photoelectric conversion element.

  In recent years, the demand for solar cells has increased, and organic electronics devices that can be expected to be lightweight (flexible) and cost-cutting have attracted attention. In particular, expectations for all-solid-state organic thin-film solar cells are increasing.

  The structure of an organic thin film solar cell (solar cell comprising an organic photoelectric conversion element) is a bulk heterostructure formed by mixing an electron donating material (donor) and an electron accepting material (acceptor) between two different electrodes (positive electrode and negative electrode). It is common to have a junction-type photoelectric conversion layer arranged, and it is easier to manufacture than conventional thin-film solar cells using amorphous silicon or the like, and solar cells of any area can be manufactured at low cost. There is an advantage that it can be obtained, and practical application is desired.

  In an organic electronic device such as an organic thin film solar cell, it is preferable from the viewpoint of power generation efficiency that the electrode on the light receiving side has high transparency. As the transparent electrode, a transparent conductive oxide (TCO) is usually used. In particular, indium tin oxide (equivalent to high visible light transmission and high electrical conductivity, and easy to process) ITO) is mainly used. However, the price of ITO materials has been rising in recent years, and high-quality ITO electrodes cannot be obtained unless they are formed by a physical vapor deposition method (PVD method) such as sputtering. . For this reason, there is a demand for an alternative electrode material.

  Moreover, when it is set as the thin film solar cell which has translucency, such as semi-transparency, both a positive electrode and a negative electrode require a light transmittance. Flexible thin-film solar cells using plastic film as a support, organic thin-film solar cells using an organic semiconductor containing a conductive polymer as a photoelectric conversion layer, and solar cells using a combination of both, have electrodes at low temperatures so that organic materials do not deteriorate. Although it is necessary to form it, when TCO such as ITO is formed at a low temperature, its crystallinity is deteriorated and the resistance of the electrode is increased.

In Patent Document 1 and Patent Document 2, after forming a mesh pattern metal electrode (mesh electrode) as a positive electrode auxiliary wiring on a support, a positive electrode (hole transport layer) made of TCO or a conductive polymer is formed, An organic thin film solar cell with reduced resistance on the positive electrode side is disclosed. However, since the portion where the positive electrode auxiliary wiring is formed is shielded from light, the effective area of the solar cell is reduced (the aperture ratio is reduced) and the conversion efficiency is deteriorated. Therefore, it is necessary to narrow the line width of the auxiliary wiring for positive electrode, while it is necessary to increase the film thickness so as not to lower the conductivity. However, since a step corresponding to the film thickness occurs at the end of the auxiliary wiring for positive electrode, the occurrence rate of short-circuit failure in which the positive electrode and the negative electrode contact and short-circuit increases. Patent Document 1 suggests that the thickness of the hole transport layer needs to be greater than or equal to the thickness of the mesh electrode. However, the increase in the thickness of the hole transport layer directly leads to an increase in cost, and the hole transport. The amount of incident light absorbed by the layer increases (transmittance decreases), leading to a further decrease in efficiency of the solar cell.
On the other hand, in Patent Document 2, when a mesh electrode having a sufficient thickness to ensure conductivity is formed so as to be embedded in a substrate (a step due to the mesh electrode is reduced), a negative electrode (counter electrode) The method which can suppress a short circuit with is effectively described.

  However, the production method described in Patent Document 2 increases the number of production steps and the process time, leading to an increase in cost. In particular, when the support is a plastic film, the support is etched or surface-polished. The support deteriorates and leads to an increase in surface irregularities, which in turn increases short circuit failures.

  Patent Document 3 discloses a conductive polymer after a transparent resin is embedded in a liquid discharge (inkjet) device only in an opening (translucent portion) of a mesh pattern metal wiring (described as a conductive metal pattern). An auxiliary electrode is disclosed in which a surface step is reduced by forming a film. However, this method greatly increases the process time including alignment.

  Furthermore, in Patent Document 3, an ultraviolet curable resin is formed on the entire surface of the support (transparent film substrate) on which the mesh pattern metal wiring is formed, and is exposed to ultraviolet light from the support (back surface) side and washed. A method of forming a transparent resin only at the metal wiring opening to eliminate the surface step is also disclosed.

US Patent Application Publication No. 2004/0187911 JP 2009-76668 A JP 2009-140750 A

  The method of eliminating the surface step by forming a transparent resin only in the metal wiring opening by forming a film of the ultraviolet curable resin described in Patent Document 3 and exposing it to ultraviolet light from the support (back surface) side and washing it. The cost can be suppressed by a relatively easy method.

  However, the cross section of the metal wiring is not an ideal rectangle and is actually a trapezoid (the cross section of the end is not a right angle but an acute angle), so according to this method, the UV curable resin formed on the slope of the end of the metal wiring Are not irradiated with ultraviolet light and are removed in the cleaning process. That is, there is a possibility that a groove in which the transparent resin is not formed is formed at the end portion of the metal wiring. When such an auxiliary electrode is used, it is considered that there is a possibility that a contact between the lower electrode and the upper electrode and a short circuit may occur due to a surface step due to the groove.

  The present invention has been made in view of the above circumstances, and includes an organic thin-film solar cell in which the lower electrode includes an auxiliary electrode having good conductivity and transparency and the occurrence of short-circuit failure is suppressed. It aims at providing the method of manufacturing at low cost.

The method for producing the solar cell of the present invention comprises:
On the support, an auxiliary electrode having an auxiliary metal wiring having a plurality of openings, and a planarization layer made of a transparent resin filled at least in the openings,
A method for producing a solar cell comprising a photoelectric conversion element in which a lower electrode, a photoelectric conversion layer containing an organic material, and an upper electrode are laminated in this order,
Forming the auxiliary metal wiring on the support;
A step of filling the opening with a transparent resin obtained by polymerizing a composition containing a polyfunctional (meth) acrylic monomer and covering the auxiliary metal wiring to form a transparent insulating layer;
Etching the transparent insulating layer until at least part of the surface of the auxiliary metal wiring is exposed and the surface of the transparent insulating layer in the opening is substantially flush with the surface of the auxiliary metal wiring;
Forming the lower electrode on the surface of the transparent insulating layer and the auxiliary metal wiring; and
A step of sequentially forming the photoelectric conversion layer and the upper electrode on the lower electrode.

  In the present specification, the “polyfunctional (meth) acrylic monomer” means a monomer (monomer) having two or more (meth) acrylic groups. “(Meth) acryl” means acrylic or methacrylic.

  In the step of forming the transparent insulating layer, it is preferable that the transparent insulating layer is formed by applying the composition to the opening and the surface of the auxiliary metal wiring and then photopolymerizing the composition.

  The polyfunctional (meth) acrylic monomer is preferably trifunctional or more, and preferably contains no oxygen in a connecting chain that connects (meth) acrylic groups.

In a preferred embodiment of the method for producing a solar cell of the present invention, in the step of forming the transparent insulating layer, the transparent insulating layer is formed after the surface of the transparent insulating layer is above the surface of the auxiliary metal wiring. Formed with a thickness that is higher than the surface of the photoelectric conversion layer,
In the step of etching the transparent insulating layer, an insulating partition in which a part of the transparent insulating layer defines at least a part of the formation region of the lower electrode on at least a part of a plane including the surface of the auxiliary metal wiring As an example, the etching is performed so as to remain. In such an embodiment, the insulating partition is formed so as to surround the formation region of the lower electrode, and the lower electrode and the photoelectric conversion layer are sequentially formed in the formation region surrounded by the insulating partition, It is preferable to form an electrode on the photoelectric conversion layer and the insulating partition so that the photoelectric conversion layer is sealed by the upper electrode and the insulating partition.

The solar cell of the present invention is provided on a support.
An auxiliary electrode having an auxiliary metal wiring having a plurality of openings, and a planarization layer made of a transparent resin filled in at least the openings,
A photoelectric conversion element formed by laminating a lower electrode, a photoelectric conversion layer containing an organic material, and an upper electrode in this order,
The planarizing layer is formed by etching so that the surface of the auxiliary metal wiring is exposed and the surface of the transparent resin in the opening is substantially flush with the surface of the auxiliary metal wiring.
The transparent resin is a resin obtained by polymerizing a composition containing a polyfunctional (meth) acrylic monomer.

  In the method for manufacturing a solar cell of the present invention, the planarizing layer for embedding the openings of the auxiliary metal wiring having a large number of openings is made of an auxiliary metal with a transparent resin obtained by polymerizing a composition containing a polyfunctional (meth) acrylic monomer After the wiring is formed so as to cover it, it is formed by etching until the surface of the auxiliary metal wiring is exposed. According to such a method, since the shape retaining property of the transparent resin of the planarization layer is high, a planarization layer having excellent surface smoothness can be formed by etching. In addition, a transparent resin obtained by polymerizing a composition containing a polyfunctional (meth) acrylic monomer is excellent in heat resistance and solvent resistance. Therefore, the transparent resin is formed on the transparent resin by heat treatment such as an annealing treatment in a subsequent step. There is little adverse effect on the smoothness of the material. Therefore, according to the present invention, an organic thin-film solar cell provided with an auxiliary electrode having good conductivity, transparency, and smoothness as an auxiliary electrode of the lower electrode, in which occurrence of short-circuit failure is suppressed, can be achieved with a low number of steps and a low number of steps. Can be manufactured at cost.

Sectional drawing which shows the manufacturing process of the manufacturing method which concerns on 1st Embodiment (the 1) Sectional drawing which shows the manufacturing process of the manufacturing method which concerns on 1st Embodiment (the 2) Sectional drawing which shows the solar cell manufactured by the manufacturing method which concerns on 1st Embodiment. The top view which shows the manufacturing process of the manufacturing method which concerns on 2nd Embodiment (the 1) Sectional drawing which shows the manufacturing process of the manufacturing method which concerns on 2nd Embodiment (the 2) Sectional drawing which shows the manufacturing process of the manufacturing method which concerns on 2nd Embodiment (the 3) Sectional drawing which shows the manufacturing process of the manufacturing method which concerns on 2nd Embodiment (the 4) Sectional drawing which shows the manufacturing process of the manufacturing method which concerns on 2nd Embodiment (the 5) Sectional drawing which shows the manufacturing process of the manufacturing method which concerns on 2nd Embodiment (the 6) Sectional drawing which shows the solar cell manufactured by the manufacturing method which concerns on 2nd Embodiment.

  Embodiments of the present invention will be described below.

(First embodiment)
The manufacturing method of the solar cell concerning the 1st Embodiment of this invention is demonstrated with reference to FIG. 1A-FIG. 1C. 1A and 1B are cross-sectional views showing manufacturing steps in the method for manufacturing a solar cell of the first embodiment, and FIG. 1C is a cross-sectional view showing the structure of the solar cell manufactured by the manufacturing method of the present embodiment. It is.

  First, as shown in FIG. 1A, auxiliary metal wiring 26 having a plurality of openings is formed on the surface of the support 10. The auxiliary metal wiring 26 is, for example, a mesh-shaped wiring, and mesh eyes serve as openings.

  The auxiliary metal wiring 26 includes, for example, a step of applying a silver halide-containing composition on the support 10 to form a silver halide-containing layer, a step of exposing a part of the silver halide-containing layer, It can be formed by sequentially performing the step of developing the silver halide-containing layer and the step of fixing the developed silver halide-containing layer to form the auxiliary wiring containing silver. A detailed method of forming the auxiliary metal wiring 26 will be described later.

  Thereafter, as shown in FIG. 1A, the opening of the auxiliary metal wiring 26 is made of a transparent resin obtained by polymerizing a composition containing a polyfunctional (meth) acrylic monomer on the support 10 on which the auxiliary metal wiring 26 is formed. And a transparent insulating layer 30 is formed so as to cover the auxiliary metal wiring 26.

  The method for forming the transparent insulating layer 30 is not particularly limited, and is formed by polymerizing a coating liquid made of a composition containing a polyfunctional (meth) acrylic monomer on the opening and the surface of the auxiliary metal wiring. It is preferable.

  At the time of application, an opening is filled with a composition (coating liquid) containing a polyfunctional (meth) acrylic monomer, and an excessive coating liquid is applied so as to cover the auxiliary metal wiring 26.

  Although the polymerization method of the composition containing a polyfunctional (meth) acryl monomer is not particularly limited, photopolymerization using light or an electron beam is preferable. It is preferable that the composition contains a suitable photopolymerization initiator depending on the type of monomer. What is necessary is just to select the wavelength of light and an electron beam suitably according to the kind of monomer and a polymerization initiator. A sensitizer may be added in relation to the irradiation light wavelength in the production process.

  Since the polyfunctional (meth) acrylic monomer can form a crosslinked structure by polymerization, the transparent insulating layer 30 having excellent heat resistance and solvent resistance as compared with the case where the monofunctional (meth) acrylic monomer is used. Can be formed. Here, the solvent resistance means resistance to organic solvents and monomers.

Although it does not restrict | limit especially as a polyfunctional (meth) acryl monomer, It is preferable that it is a monomer which has 3 or more (henceforth trifunctional or more) (meth) acryl groups. As the trifunctional (meth) acrylic monomer, the following trimethylolpropane triacrylate (TMPTA) and pentaerythritol triacrylate (PETIA) can be preferably used.

As the bifunctional (meth) acrylic monomer, the following 1,6-hexanediol diacrylate can be preferably used.

The polyfunctional (meth) acryl monomer has a plurality of (meth) acryl groups. A resin obtained by polymerizing a polyfunctional (meth) acrylic monomer having a structure containing an oxygen atom in a portion (linking chain) that connects (meth) acrylic groups like the following polyethylene glycol diacrylate (A-600) The shape retention is lower than that of a structure not containing oxygen atoms. Therefore, as a polyfunctional (meth) acryl monomer, what has a structure which does not contain an oxygen atom in the part (connection chain) which connects (meth) acryl groups is preferable.

Examples of other bifunctional (meth) acrylic monomers include the following compounds.

  The composition containing a polyfunctional (meth) acrylic monomer may contain other vinyl monomers. The composition ratio of the polyfunctional (meth) acrylate monomer in the composition containing the polyfunctional (meth) acrylate monomer is preferably 50% by mass to 100% by mass, more preferably 60% by mass to 100% by mass, Furthermore, it is more preferable that it is 70 mass%-100 mass%.

Examples of vinyl monomers include (meth) acrylate, (meth) acrylamide, styrene and the like, and monofunctional (meth) acrylate monomers are preferred. Although the preferable specific example of a monofunctional (meth) acrylate monomer is shown below, this invention is not limited to these.

  Next, as shown in FIG. 1B, the excess transparent insulating layer 30 deposited on the auxiliary metal wiring 26 is exposed to the surface of the auxiliary metal wiring 26 and the surface of the insulating layer 30 embedded in the opening is the auxiliary metal. Etching is performed until the surface of the wiring 26 is substantially flush with the surface of the wiring 26. Here, the insulating layer 30 embedded in the opening portion of the auxiliary metal wiring and having a surface substantially the same as the surface of the auxiliary metal wiring 26 by etching is referred to as a flattening layer 31, and the auxiliary metal wiring 26 and the flattening layer 31 The configured electrode is referred to as auxiliary electrode 11.

  The etching method of the transparent insulating layer 30 is not particularly limited, and various dry etching (for example, reactive ion etching, plasma etching, etc.) can be used. Among them, plasma etching is preferable, and oxygen plasma etching is particularly preferable.

  In the plasma etching, the carbon-carbon bond constituting the resin is cut and the resin is scraped. Therefore, the surface of the transparent insulating layer 30 after the auxiliary metal wiring 26 is just exposed and the etching is finished usually receives plasma damage. . Although it has already been described that a polymer of a composition containing a polyfunctional (meth) acrylic monomer can form a crosslinked structure, when it has a crosslinked structure, shape retention is high, and dry etching property, particularly plasma resistance is enhanced. Therefore, the plasma damage is small, and as a result, the flatness of the planarizing layer 31 is ensured. Further, the auxiliary electrode 11 with good flatness has almost no step between the auxiliary metal wiring 26 and the planarizing layer 31. Can be formed.

  The upper portions of the planarization layer 31 and the auxiliary metal wiring 26 are preferably flush with each other, but a level difference sufficient to ensure the flatness of the lower electrode layer 12 formed thereon is allowed. The step between the planarization layer 31 and the upper portion of the auxiliary metal wiring 26 is preferably 1 μm or less, more preferably 500 nm or less, and further preferably 200 nm or less.

  As described above, according to the manufacturing method of the present embodiment, it is possible to manufacture the auxiliary electrode 11 having the auxiliary metal wiring 26 with good flatness by filling the opening of the auxiliary metal wiring 26 well. In this method, since the auxiliary metal wiring 26 can be formed thick, the auxiliary electrode 11 having high conductivity and transparency can be formed.

  Next, the lower electrode layer 12 is formed on the auxiliary electrode 11 composed of the auxiliary metal wiring 26 and the planarizing layer 31. The lower electrode layer 12 can be manufactured, for example, by forming a conductive polymer on the surface of the auxiliary electrode 11 by, for example, an aqueous coating method.

  When the lower electrode layer 12 is formed, the surface of the auxiliary electrode 11 (flattening layer 31) serving as the base may affect the smoothness depending on the formation method and the material of the lower electrode layer 12. For example, when the lower electrode layer 12 made of a conductive polymer is formed by a coating method, the surface smoothness is lowered if the resistance of the planarizing layer 31 to the coating solution is low. In addition, when the heating process is required at the time of forming the lower electrode layer 12 or subsequent annealing treatment or the like, if the heat resistance of the planarizing layer 31 is low, the smoothness is impaired. As described above, since the planarization layer 31 of this embodiment is excellent in heat resistance and solvent resistance, good smoothness can be maintained even when the lower electrode layer 12 is formed.

  Before and during the formation of the lower electrode layer 12 (during formation), the transparent insulating layer 30 rises from the auxiliary metal wiring 26 in the auxiliary electrode 11, or the auxiliary metal wiring 26 is opened by the transparent insulating layer 30. When the portion is not filled, a step is generated in the portion that is not flattened. If this step is present, the thickness of the lower electrode layer 12 at that portion is reduced, and therefore, in an organic thin film solar cell, a short circuit with the upper electrode is likely to occur at the corner of the step, which adversely affects conversion efficiency.

  As described above, according to the present invention, the flatness of the auxiliary electrode 11 can be improved, so that the uniformity of the film thickness of the lower electrode layer 12 is improved and short-circuiting in the solar cell is less likely to occur. it can.

  Next, a photoelectric conversion layer 15 including at least an organic material is stacked on the lower electrode layer 12. The solar cell 1 shown in FIG. 1C can further include a semiconductor layer 13 such as a hole transport layer between the lower electrode 12 and the photoelectric conversion layer 15.

Furthermore, the solar cell 1 as shown in FIG. 1C is formed by forming the upper electrode 21 on the photoelectric conversion layer 15. A semiconductor layer such as an electron transport layer may be provided between the photoelectric conversion layer 15 and the upper electrode 21.
The solar cell 1 can be manufactured as described above.

In the method for manufacturing the solar cell 1 of the present embodiment, the planarization layer 31 that fills the openings of the auxiliary metal wiring 26 having a large number of openings is transparentized by polymerizing a composition containing a polyfunctional (meth) acrylic monomer. After the auxiliary metal wiring 26 is formed so as to cover the resin, it is formed by etching until the surface of the auxiliary metal wiring 26 is exposed. According to this method, since the shape retaining property of the transparent resin of the planarizing layer 31 is high, the planarizing layer 31 having good surface smoothness can be formed by etching. In addition, a transparent resin obtained by polymerizing a composition containing a polyfunctional (meth) acrylic monomer is excellent in heat resistance and solvent resistance. Therefore, the transparent resin is formed on the transparent resin by heat treatment such as an annealing treatment in a subsequent step. There is little adverse effect on the smoothness of the material.
Therefore, according to the present invention, as the auxiliary electrode 11 of the lower electrode layer 12, the organic thin-film solar cell 1 provided with the auxiliary electrode 11 having good conductivity, transparency and smoothness, and the occurrence of short-circuit failure is suppressed. It can be manufactured with a low number of steps and low cost.

(Second Embodiment)
A method for manufacturing a solar cell according to the second embodiment of the present invention will be described with reference to FIGS. 2A to 2G. 2A to 2F show manufacturing steps in the method for manufacturing a solar cell according to the second embodiment. FIG. 2A is a plan view, FIGS. 2B to 2F are sectional views, and FIG. 2G is the present embodiment. It is sectional drawing which shows the structure of the solar cell manufactured by this manufacturing method. In addition, the same code | symbol is attached | subjected to the element same as the component of the solar cell of 1st Embodiment, and detailed description is abbreviate | omitted.

First, as shown in FIG. 2A, the auxiliary metal wiring 25 is formed on the surface of the support 10. As the auxiliary metal wiring, as shown in FIG. 2A, a mesh-like wiring 26 is provided in a region corresponding to the element formation position, and a slightly thick line-like wiring (bus line) 27 is provided at both ends thereof. Provide continuously in the wiring.
When forming the auxiliary metal wiring 25, it is preferable that the alignment mark (position detection mark) 28 having a cross pattern is simultaneously formed of the same material as the auxiliary metal wiring.

  By forming the alignment mark 28 in advance, the alignment mark is used as a reference point for alignment in the subsequent process, and is accurately insulated to a desired position using various manufacturing apparatuses and printing apparatuses having an image recognition function. A functional film such as a conductive partition can be formed.

  As shown in FIG. 2B, between the mesh-like wirings 26 of the auxiliary metal wiring 25 and a region where no auxiliary metal wiring other than the element formation position is formed (hereinafter, both are collectively referred to as a wiring opening). Then, the transparent insulating layer 30 is formed so as to embed the auxiliary metal wiring 25.

  For example, by applying a photo-curable material such as acrylic or epoxy, and irradiating the entire surface with light having a wavelength suitable for the material, the auxiliary metal wiring 25 is covered with a transparent insulating layer 30 made of a photo-curable resin. To do. The transparent insulating layer 30 can also be formed using a thermosetting material or an electron beam curable material.

  Further, as shown in FIG. 2C, a photo-curing material is further applied on the transparent insulating layer 30 to form a coating film 30a, and the insulating mark 28 made of silver is formed as a reference point for alignment. Only the portion where the conductive barrier rib is formed is irradiated with light through the photomask 50, and only this portion is cured. At this time, the coating film 30a may be formed of a transparent insulating material different from the material of the previously provided transparent insulating layer.

  Thereafter, if the uncured photocurable material is washed with an appropriate solvent, the exposed portion of the coating film 30a can be removed as shown in FIG. 2D. Thereby, the thick transparent insulating layer 30 is formed in the part which irradiated light twice.

  Next, as in the case of the first embodiment, the surface of the photocurable resin is changed until the surface of the auxiliary metal wiring 25 and the surface of the transparent insulating layer 30 formed in the auxiliary metal wiring opening are substantially flush with each other. The planarizing layer 31 is formed by plasma etching (see FIG. 2E). During this etching, the thick portion of the transparent insulating layer 30 remains as an insulating partition wall 32 that divides at least a part of a formation region of a lower electrode to be formed later. At this time, the insulating partition 32 is erected so that the surface thereof is positioned higher than the surface of the photoelectric conversion layer formed in a later step.

  Thereafter, as shown in FIG. 2F, a lower electrode 12, a semiconductor layer 13 such as a hole transport layer, and a photoelectric conversion layer 15 including an organic material are sequentially stacked. Further, on the photoelectric conversion layer 15, an insulating partition wall 32 and The upper electrode layer 20 is formed on the exposed planarization layer 31 at the end.

  Of the electrode layer 20, a portion formed immediately above the photoelectric conversion layer 15 functions as the upper electrode 21, and an end region continuously formed from the upper electrode 21 functions as the external connection terminal 23.

  Next, the protective layer 40 is formed so as to cover the upper electrode 21 and the partially exposed lower electrode 12, the semiconductor layer 13 such as a hole transport layer, and the photoelectric conversion layer 15.

  Finally, the sealing film 41 is disposed on the protective layer 40 and laminated, whereby the solar cell 2 shown in FIG. 2G can be manufactured.

  In the present embodiment, the insulating partition 32 can be formed at the same time in the process of forming the planarization layer 31. The insulating partition 32 may be formed in a separate step after the step of forming the planarization layer 31. However, as in this embodiment, by forming the insulating partition simultaneously with the planarization layer, the insulating partition 32 can be formed without increasing the number of steps so much, and the photoelectric conversion elements having various structures. Can be formed on the support.

  For example, by providing the insulating partition wall 32 that surrounds the formation region of the lower electrode 12 and whose surface position is higher than the surface position of the photoelectric conversion layer 15, the photoelectric conversion layer 15 is made to have the insulating partition wall 32 and the upper electrode layer. It can be set as the structure sealed between 20. Thus, durability can be further improved by setting it as the structure which seals the photoelectric converting layer 15 which consists of organic materials.

  In the said embodiment, although the solar cell which consists of a single photoelectric conversion element was demonstrated, the manufacturing method of this invention can be similarly applied to manufacture of the integrated solar cell which connected the some photoelectric conversion element in series. it can.

  When manufacturing an integrated solar cell, the auxiliary metal wiring 25 separated between elements is formed on the support 10 so as to correspond to each element. In addition, the insulating partition 32 is formed at least between the elements so that the lower electrodes and the photoelectric conversion layers do not contact between adjacent elements. By forming the upper electrode layer 20 so as to be in contact with the lower electrode layer 12 or the auxiliary metal wiring 25 between the elements, the inter-element region of the upper electrode layer 20 functions as an electrode connection wiring portion, and the elements are connected in series. Can be connected.

  Hereinafter, materials and the like that can be preferably used in the method for producing the solar cell of the present invention will be described in detail.

<Support>
The support 10 is not particularly limited as long as it is a smooth substrate or film that can hold the auxiliary metal wiring 26 (25) and the flattening layer 31, and can be appropriately selected according to the purpose. A support having light permeability is preferred. Examples include a plastic film and a thin glass plate. In addition, when a solar cell is formed using a temporary support, and the temporary support is peeled off and the solar cell is disposed on an arbitrary transparent support, the temporary support does not particularly need transparency. A plastic film, a metal foil, a laminate in which plastic or metal is laminated on paper, and the like can be arbitrarily selected and used.

  Hereinafter, a plastic film substrate will be described as a representative example of the transparent support.

(Plastic film substrate)
There is no restriction | limiting in particular in a material, thickness, etc., a plastic film board | substrate can be suitably selected according to the objective. Specific examples of the plastic film material that can be used for the substrate include polyester resin, methacrylic resin, methacrylic acid-maleic acid copolymer, polystyrene resin, transparent fluororesin, polyimide resin, fluorinated polyimide resin, and polyamide resin. , Polyamideimide resin, polyetherimide resin, cellulose acylate resin, polyurethane resin, polyetheretherketone resin, polycarbonate resin, cycloaliphatic polyolefin resin, polyarylate resin, polyethersulfone resin, polysulfone resin, cycloolefin copolymer, Examples thereof include thermoplastic resins such as a fluorene ring-modified polycarbonate resin, an alicyclic ring-modified polycarbonate resin, a fluorene ring-modified polyester resin, and an acryloyl compound.

  A heat resistant resin having a high Tg is also preferably used as the plastic film substrate. Examples of the heat resistant resin include, for example, polyethylene naphthalate (PEN: 120 ° C.), polycarbonate (PC: 140 ° C.), alicyclic polyolefin (for example, Zeonore 1600: 160 ° C. manufactured by Nippon Zeon Co., Ltd.) 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 disclosed in JP 2000-227603 A: 225 ° C., alicyclic modified polycarbonate (IP-PC: Compound disclosed in JP 2000-227603 A: 205 ° C.), acryloyl compound (JP 2002-80616 A) Compound: 300 ° C. or higher) Imide and the like (in parentheses indicate the Tg), they are suitable as substrates in the present invention.

  In the present invention, the plastic film is required to be transparent to light. More specifically, the light transmittance for light in the wavelength range of 400 nm to 800 nm is usually preferably 80% or more, more preferably 85% or more, and further preferably 90% or more. The light transmittance can be measured as the total light transmittance using an integrating sphere light transmittance measuring device. Although there is no restriction | limiting in particular regarding the thickness of a plastic film, Typically, they are 1 micrometer-800 micrometers, Preferably they are 10 micrometers-300 micrometers.

(Easily adhesive layer / undercoat layer)
The plastic film substrate may have an easy adhesion layer or an undercoat layer. The structure of the easy adhesion layer or the undercoat layer may be a single layer or a multilayer structure. The easy-adhesion layer must contain a binder polymer, but may appropriately contain a matting agent, a surfactant, an antistatic agent, fine particles for controlling the refractive index, and the like. There is no restriction | limiting in particular in the binder polymer which can be used for an easily bonding layer, It can select suitably from an acrylic resin, a polyurethane resin, a polyester resin, a rubber-type resin, etc., and can be used.

  The coating film thickness after drying the easy-adhesion layer or the undercoat layer is preferably in the range of 50 nm to 2 μm. In addition, when using a support body as a temporary support body, it is also possible to give an easily peelable process to the support surface.

  An acrylic resin is a polymer containing acrylic acid, methacrylic acid and derivatives thereof as components. Specifically, for example, acrylic acid, methacrylic acid, methyl methacrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, acrylamide, acrylonitrile, hydroxyl acrylate, and the like as a main component and a monomer copolymerizable therewith (for example, styrene, A polymer obtained by copolymerizing divinylbenzene or the like is preferable.

  Polyurethane resin is a general term for polymers having a urethane bond in the main chain, and is usually obtained by reaction of polyisocyanate and polyol. Examples of the polyisocyanate include TDI (Tolylene Diisocyanate), MDI (Methyl Diphenylisocyanate), HDI (Hexylene diisocyanate), IPDI (Isophoron diisocyanate), and the like. And pentaerythritol. Furthermore, as the isocyanate of the present invention, a polymer obtained by subjecting a polyurethane polymer obtained by the reaction of polyisocyanate and polyol to chain extension treatment to increase the molecular weight can also be used.

  A polyester resin is a general term for polymers having an ester bond in the main chain, and is usually obtained by the reaction of a polycarboxylic acid and a polyol. Examples of the polycarboxylic acid include fumaric acid, itaconic acid, adipic acid, sebacic acid, terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid. Examples of the polyol include those described above.

  The rubber-based resin refers to a diene-based synthetic rubber among the synthetic rubbers. Specific examples include polybutadiene, styrene-butadiene copolymer, styrene-butadiene-acrylonitrile copolymer, styrene-butadiene-divinylbenzene copolymer, butadiene-acrylonitrile copolymer, and polychloroprene.

<Auxiliary electrode>
<< Auxiliary metal wiring >>
Examples of the metal material constituting the auxiliary metal wiring 26 (25) include gold, platinum, iron, copper, silver, aluminum, chromium, cobalt, and stainless steel. Preferable examples of the metal material include low resistance metals such as copper, silver, aluminum, and gold. Among them, silver or copper that is low in manufacturing cost and material cost and hardly oxidizes is preferably used.

  The pattern shape of the auxiliary metal wiring 26 (25) is not particularly limited, but a mesh shape (mesh pattern electrode) is preferable from the viewpoint of light transmittance and conductivity. There is no particular limitation on the mesh pattern, and a lattice shape such as a square, a rectangle, or a rhombus, a stripe shape (stripe shape), a honeycomb, or a combination of curves may be used.

  These mesh designs are adjusted so that the aperture ratio (light transmittance) and the surface resistance (electric conductivity) become desired values. When the auxiliary metal wiring 26 having such a mesh pattern is used, the mesh opening ratio is usually 70% or more, preferably 80% or more, and more preferably 85% or more.

  The surface resistance of the auxiliary metal wiring 26 (25) is preferably 10Ω / □ or less, more preferably 3Ω / □ or less, and even more preferably 1Ω / □ or less. Since the light transmittance and the electrical conductivity are in a trade-off relationship, the larger the aperture ratio, the better. However, in practice, it becomes 95% or less.

  The thickness of the auxiliary metal wiring 26 (25) is not particularly limited, but is usually about 0.02 μm to 20 μm.

  The line width in the mesh pattern of the auxiliary metal wiring 26 (25) is from 1 μm to 500 μm, preferably from 1 μm to 100 μm, more preferably from 3 μm to 20 μm, from the viewpoint of light transmittance and conductivity. preferable.

  A smaller pitch (fine mesh) in the mesh pattern of the auxiliary metal wiring 26 (25) is advantageous in terms of the characteristics of the solar cell. However, if the pitch is small, the light transmittance decreases, so a compromise is chosen. Although a pitch changes according to the line | wire width of a metal fine wire, it is preferable that the pitch by planar view is 50 micrometers-2000 micrometers, 100 micrometers-1000 micrometers are more preferable, 150 micrometers-500 micrometers are more preferable.

From the viewpoint of the opening, the area of the opening serving as a repeating unit of the auxiliary metal wiring 26 (25) is preferably 1 × 10 ⁻⁹ m ² to 1 × 10 ⁻⁴ m ² , and 3 × 10 ^−9. m ² to 1 × 10 ⁻⁵ m ² is more preferable, and 1 × 10 ⁻⁸ m ² to 1 × 10 ⁻⁶ m ² is even more preferable.

  There is no restriction | limiting in particular as a formation method of the auxiliary metal wiring 26 (25), A well-known formation method can be used suitably. For example, a method in which a mesh pattern metal prepared in advance is bonded to the support surface, a method in which a conductive material is applied to the mesh pattern, a conductive film is formed on the entire surface using a PVD method such as vapor deposition or sputtering, and then the mesh pattern is etched. A method of forming a conductive film, a method of applying a conductive material of a mesh pattern by various printing methods such as screen printing, ink jet printing, etc., a metal mask of a mesh pattern directly on the substrate surface using a shadow mask by vapor deposition or sputtering And a method using a silver halide photosensitive material described in JP-A-2006-352073, JP-A-2009-231194, and the like (hereinafter sometimes referred to as silver salt method).

  When the auxiliary metal wiring 26 (25) is formed as a mesh electrode, it is preferably formed by a silver salt method because the pitch is small. When forming the auxiliary metal wiring 25 by the silver salt method, a step of providing a coating liquid for forming the auxiliary metal wiring on the support and performing pattern exposure on the coating film for forming the auxiliary metal wiring 25; The auxiliary metal wiring 26 (25) having a desired pattern can be formed on the support by developing the pattern-exposed coating film and fixing the developed coating film.

  The auxiliary metal wiring 26 (25) produced by the silver salt method is a layer of silver and a hydrophilic polymer. Examples of the hydrophilic polymer include water-soluble polymers such as gelatin, gelatin derivatives, casein, agar, sodium alginate, starch, and polyvinyl alcohol, and cellulose esters such as carboxymethyl cellulose and hydroxyethyl cellulose. In addition to silver and hydrophilic polymer, the layer contains substances derived from the coating, developing and fixing processes.

  A method of forming an auxiliary wiring by the silver salt method and then performing copper plating to obtain an auxiliary wiring with lower resistance is also preferably used.

<< Alignment mark >>
In the process of forming the auxiliary metal wiring 25, in order to improve the overlay accuracy of each functional film and film substrate to be stacked in the subsequent process and increase the integration density, the position detection alignment mark 28 is formed simultaneously with the metal wiring. It is preferable to do. The alignment mark appropriately forms a pattern specified by the image recognition specifications of each functional film manufacturing device or printing device, but stripes, crosses, rectangles, circles, geometric patterns combining them, symbols, characters, etc. Are preferably used.

<< Planarization layer, insulating partition wall >>
The materials for the planarization layer 31 and the insulating partition wall 32 and the preferred manufacturing method have already been described.

  In the case of manufacturing a solar cell including the insulating partition 32, the planarization layer 31 and the insulating partition 32 can be manufactured in separate processes, but as described in the second embodiment, the same process is performed. It is preferable to produce by.

<Lower electrode layer>
The lower electrode layer 12 is selected from various conductive materials having optical transparency. Examples of the light-transmitting conductive material include a transparent conductive polymer, ITO (indium tin oxide), and the like, but a layer containing a conductive polymer as a main component is preferable because of excellent flexibility. Details of a conductive polymer layer suitable for the lower electrode are disclosed in Japanese Patent Application No. 2010-181078 (not disclosed at the time of this application).

  The positive electrode of the solar cell constituted by the auxiliary electrode 11 and the lower electrode layer 12 has a surface resistance value of preferably 20 Ω / sq or less, more preferably 10 Ω / sq or less, and more preferably 1 Ω / sq or less. More preferably (measured according to JIS 7194). Further, the average transmittance in the light wavelength range of 400 nm to 800 nm is 50% or more, preferably 60% or more, and more preferably 70% or more. Similar to the support, the light transmittance can be measured as the total light transmittance using an integrating sphere light transmittance measuring device. Further, molybdenum oxide may be used as part of the positive electrode.

<Functional layer>
A functional layer may be provided on the back side of the support 10 (the side on which the lower electrode is not formed). Examples thereof include a gas barrier layer, a matting agent layer, an antireflection layer, a hard coat layer, an antifogging layer, an antifouling layer, and an easy adhesion layer. In addition, the functional layer is described in detail in paragraphs [0036] to [0038] of JP-A-2006-289627, and the functional layer described herein may be provided according to the purpose.

<Photoelectric conversion layer>
After the photoelectric conversion layer 15 receives sunlight and generates excitons (electron-hole pairs), the excitons dissociate into electrons and holes, and electrons move to the negative electrode side and holes move to the positive electrode side. The photoelectric conversion process of being transported is selected from materials that are expressed with high efficiency. In the case of an organic thin film solar cell, a photoelectric conversion layer 15 including an electron donating region (donor) made of an organic material is formed, and from the viewpoint of conversion efficiency, a bulk heterojunction type photoelectric conversion layer (as appropriate, “to bulk”). "Terrorism layer") is preferably applied.

  The bulk hetero layer is an organic photoelectric conversion layer in which an electron donating material (donor) and an electron accepting material (acceptor) are mixed. The mixing ratio of the electron donating material and the electron accepting material is adjusted so that the conversion efficiency is the highest, but is usually selected from the range of 10:90 to 90:10 by mass ratio. As a method for forming such a mixed layer, for example, a co-evaporation method is used. Or it is also possible to produce by carrying out solvent application | coating using the solvent common to both organic materials.

The thickness of the bulk hetero layer is preferably 10 to 500 nm, particularly preferably 20 to 300 nm.

  An electron-donating material (also referred to as a donor or a hole-transporting material) is a π-electron conjugated compound having a maximum occupied orbital (HOMO) level of 4.5 to 6.0 eV. Conjugated polymers obtained by coupling arenes (for example, thiophene, carbazole, fluorene, silafluorene, thienopyrazine, thienobenzothiophene, dithienosilol, quinoxaline, benzothiadiazole, thienothiophene, etc.), phenylene vinylene polymers, porphyrins, phthalocyanines, etc. Is exemplified. In addition, the compound group described as Hole-Transporting Materials in Chemical Review Vol. 107, 953-1010 (2007) and the Porphyrin described in Journal of the American Chemical Society Vol. 131, page 16048 (2009) Derivatives 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 (P3HT), poly-3-octylthiophene (P3OT), various polythiophene derivatives described in Journal of the American Chemical Society Vol. 130, p. 3020 (2008), and Advanced Materials. PCTBT described in Vol. 19, page 2295 (2007), Journal of the American Chemical Society vol. 130, PCDTQx, PCDTPP, PCDTPT, PCDTBX, PCDTPX, Nature Photonics vol. 3, described in page 732 (2008), PBDTTT-E, PBDTTTT-C, PBDTTTT-CF described in page 649 (2009), PTB7 described in Advanced Materials Vol. 22, E135-E138 (2010), and the like. It is done.

An electron-accepting material (also referred to as an acceptor or an electron-transporting material) is a π-electron conjugated compound having a lowest orbital (LUMO) level of 3.5 to 4.5 eV, specifically fullerene and Examples thereof include phenylene vinylene-based polymers, naphthalene tetracarboxylic imide derivatives, and perylene tetracarboxylic imide derivatives. Of these, fullerene derivatives are preferred. Specific examples of the fullerene derivative include C ₆₀ , phenyl-C ₆₁ -butyric acid methyl ester (fullerene derivatives referred to as PCBM, [60] PCBM, or PC ₆₁ BM in literatures), C ₇₀ , phenyl-C ₇₁ -butyric acid. Methyl esters (fullerene derivatives referred to as PCBM, [70] PCBM, or PC ₇₁ BM in many literatures) and fullerene derivatives described in Advanced Functional Materials, Vol. 19, pp. 779-788 (2009) And the fullerene derivative SIMEF described in Journal of the American Chemical Society, vol. 131, page 16048 (2009).

<Electron transport layer>
If necessary, an electron transport layer made of an electron transport material may be disposed between the photoelectric conversion layer (bulk hetero layer) 15 and the negative electrode. Examples of the electron transporting material that can be used for the electron transporting layer include the electron-accepting materials mentioned in the photoelectric conversion layer and Electron-Transporting and Hole-Blocking Materials in Chemical Review Vol. 107, pages 953 to 1010 (2007). Are described. Various metal oxides are also preferably used as materials for highly stable electron transport layers, such as lithium oxide, magnesium oxide, aluminum oxide, calcium oxide, titanium oxide, zinc oxide, strontium oxide, niobium oxide, ruthenium oxide, and indium oxide. Zinc oxide and barium oxide. Of these, relatively stable aluminum oxide, titanium oxide, and zinc oxide are more preferable. The film thickness of the electron transport layer is 0.1 to 500 nm, preferably 0.5 to 300 nm. The electron transport layer can be suitably formed by any of a wet film formation method by coating or the like, a dry film formation method by PVD method such as vapor deposition or sputtering, a transfer method, or a printing method.

<Other semiconductor layers>
If necessary, it may have auxiliary layers such as a hole injection layer, a hole transport layer, an electron blocking layer, an electron injection layer, a hole blocking layer, and an exciton diffusion preventing layer. In the present invention, a bulk hetero layer, a hole injection layer, a hole transport layer, an electron blocking layer, an electron injection layer, an electron transport layer, a hole blocking layer, formed between the lower electrode 12 and the upper electrode 21, The term “semiconductor layer” is used as a general term for layers that transport electrons and holes, such as an exciton diffusion prevention layer.

<Upper electrode (negative electrode)>
The material constituting the upper electrode can be appropriately selected from known electrode materials. When the upper electrode functions as a negative electrode, metals such as magnesium, aluminum, calcium, titanium, chromium, manganese, iron, copper, zinc, strontium, silver, indium, tin, barium, bismuth, and alloys thereof are preferably used. . When the upper electrode functions as a positive electrode, metals such as cobalt, nickel, copper, molybdenum, palladium, silver, tantalum, tungsten, platinum, and gold, alloys thereof, TCO, and conductive polymers are preferably used. These may be used alone, or two or more may be mixed or laminated.

  There is no restriction | limiting in particular about the formation method of an upper electrode, According to a well-known method, it can carry out. For example, from the wet film forming method by coating or printing, the vacuum deposition method, the sputtering method, the PVD method such as the ion plating method, the dry film forming method by various chemical vapor deposition methods (CVD method), etc. It can be formed according to a method appropriately selected in consideration of suitability with the constituent material.

  The patterning for forming the upper electrode may be performed by chemical etching such as photolithography, physical etching by laser, or the like, or may be performed by vacuum deposition or sputtering with a shadow mask overlapped. It may be performed by a lift-off method or a printing method.

  Further, a dielectric layer made of an alkali metal or alkaline earth metal fluoride or oxide may be inserted between the negative electrode and the semiconductor layer in a thickness of 0.1 to 5 nm. This dielectric layer can also be regarded as a kind of electron injection layer. The dielectric layer can be formed by, for example, a PVD method such as a vacuum deposition method, a sputtering method, or an ion plating method.

  The thickness of the upper electrode can be appropriately selected depending on the constituent material and cannot be generally defined. However, from the viewpoint of conductivity, it is usually about 0.01 μm to 10 μm, preferably 0.05 μm to 1 μm. .

<Protective layer>
Examples of the material of the protective layer 40 include metal oxides such as magnesium oxide, aluminum oxide, silicon oxide (SiO _x ), titanium oxide, germanium oxide, yttrium oxide, zirconium oxide, and hafnium, and metals such as silicon nitride (SiN _x ). Metal nitride oxide (metal oxynitride) such as nitride, silicon nitride oxide (SiO _x N _y ), metal fluoride such as lithium fluoride, magnesium fluoride, aluminum fluoride, calcium fluoride, diamond-like carbon ( Inorganic materials such as DLC). Examples of the organic material include polymers such as polyethylene, polypropylene, polyvinylidene fluoride, polyparaxylylene, and polyvinyl alcohol. Of these, metal oxides, nitrides, nitride oxides and DLC are preferred, and silicon, aluminum oxides, nitrides and nitride oxides are particularly preferred. The protective layer may be a single layer or a multilayer structure. The method for forming the protective layer is not particularly limited. For example, the vacuum deposition method, the sputtering method, the MBE (molecular beam epitaxy) method, the cluster ion beam method, the ion plating method, the plasma polymerization method, or the like, Various CVD methods including a layer deposition method (ALD method or ALE method), coating methods, printing methods, and transfer methods can be applied.

<Gas barrier layer>
A protective layer intended to prevent the penetration of active factors such as water molecules and oxygen molecules is also called a gas barrier layer, and the organic thin-film solar cell preferably has a gas barrier layer. The gas barrier layer is not particularly limited as long as it is a layer that blocks active factors such as water molecules and oxygen molecules, but the materials exemplified above as the protective layer are usually used. These may be pure substances, or may be a mixture of multiple compositions or a gradient composition. Of these, silicon, aluminum oxide, nitride, and nitride oxide are preferable.

  The gas barrier layer may be a single layer or a plurality of layers. An organic material layer and an inorganic material layer may be laminated, or a plurality of inorganic material layers and a plurality of organic material layers may be alternately laminated. Although there will be no restriction | limiting in particular if an organic material layer has smoothness, The layer etc. which consist of a polymer of (meth) acrylate are illustrated preferably. The above-mentioned protective layer material is preferable for the inorganic material layer, and silicon, aluminum oxide, nitride, and nitride oxide are particularly preferable.

  Although it does not specifically limit regarding the thickness of an inorganic material layer, It attaches to 1 layer, Usually, it is 5-500 nm, Preferably it is 10-200 nm. The inorganic material 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. Further, as disclosed in US Patent Application Publication No. 2004/0046497, the interface with the organic material layer made of a polymer is not clear, and the layer may be a layer whose composition changes continuously in the film thickness direction. .

<Sealing film>
In the present invention, a gas barrier layer formed in advance on a plastic film substrate is expressed as a sealing film. A production method of bonding a sealing film with a known adhesive or sealant after forming a solar cell made of an organic photoelectric conversion element is preferably used because the number of production steps of the solar cell can be reduced. In particular, when the support 10 of the solar cell is made of a plastic film, active molecules such as water molecules and oxygen molecules penetrate from the back surface (surface not forming the lower electrode) side of the support. It is preferable to attach (laminate) the sealing film to the substrate.

  Although the thickness of the solar cell manufactured by the manufacturing method according to the present invention is not particularly limited, when an organic thin film solar cell having light transmittance is preferably 50 μm to 1 mm, and preferably 100 μm to 500 μm. More preferred.

  The present invention will be described more specifically with reference to the following examples.

Example 1
As Example 1, solar cell 1 was manufactured according to the manufacturing method of the first embodiment shown in FIGS. 1A to 1C.

  A polyethylene naphthalate (PEN) film (100 μm thickness, 50 mm square) was used as the support 10, and a square grid auxiliary metal wiring 26 having a width of 0.01 mm, a pitch of 0.2 mm, and a thickness of 2 μm was formed on the PEN film. .

  The method for forming the auxiliary metal wiring was as follows.

[Preparation of silver halide emulsion]
The following solution A was kept at 34 ° C. in the reaction vessel, and the hydrogen ion concentration pH was adjusted to 2 using nitric acid (concentration 6%) while stirring at high speed using the mixing and stirring apparatus described in JP-A-62-160128. .95. Subsequently, the following solution B and the following solution C were added at a constant flow rate over 8 minutes and 6 seconds using the double jet method. After completion of the addition, the pH was adjusted to 5.90 using sodium carbonate (concentration 5%), and then the following solution D and solution E were added.

(Solution A)
Alkali-treated inert gelatin (average molecular weight 100,000) 18.7g
Sodium chloride 0.31g
Solution I (below) 1.59 cm ³
Pure water 1,246cm ³

(Solution B)
169.9g of silver nitrate
Nitric acid (concentration 6%) 5.89 cm ³
The total amount was 317.1 cm ³ with pure water.

(Solution C)
Alkali-treated inert gelatin (average molecular weight 100,000) 5.66 g
Sodium chloride 58.8g
13.3 g of potassium bromide
Solution I (below) 0.85 cm ³
Solution II (below) 2.72 cm ³
The total amount was 317.1 cm ³ with pure water.

(Solution D)
2-Methyl-4hydroxy-1,3,3a, 7-tetraazaindene 0.56 g
Pure water 112.1cm ³

(Solution E)
Alkali-treated inert gelatin (average molecular weight 100,000) 3.96 g
Solution I (below) 0.40 cm ³
Pure water 128.5cm ³

<Solution I>
10% by mass methanol solution of polyisopropylene polyethylene oxydioxalate sodium salt

<Solution II>
10% by weight aqueous solution of rhodium hexachloride complex

  After completion of the above operation, desalting and washing with water using a flocculation method are performed at 40 ° C. according to a conventional method. To 90.90 to obtain a silver chlorobromide cubic grain emulsion finally containing 10 mol% of silver bromide and having an average grain size of 0.09 μm and a coefficient of variation of 10%.

(Solution F)
Alkali-treated inert gelatin (average molecular weight 100,000) 16.5g
Pure water 139.8cm ³

  The silver chlorobromide cubic grain emulsion was subjected to chemical sensitization at 40 ° C. for 80 minutes using 20 mg of sodium thiosulfate per mol of silver halide, and after completion of chemical sensitization, 4-hydroxy-6-methyl-1, 500 mg of 3,3a, 7-tetrazaindene (TAI) per 1 mol of silver halide and 150 mg of 1-phenyl-5-mercaptotetrazole per 1 mol of silver halide were added to obtain a silver halide emulsion. This silver halide emulsion had a volume ratio of silver halide grains to gelatin (silver halide grains / gelatin) of 0.625.

[Application]
Furthermore, tetrakis (vinylsulfonylmethyl) methane was added as a hardening agent at a ratio of 200 mg / g gelatin, and di (2-ethylhexyl) sodium sulfosuccinate was added as a coating aid (surfactant). The surface tension was adjusted.

The coating solution thus obtained was applied onto a PEN film substrate (support) with an undercoat layer so that the basis weight in terms of silver was 0.625 g · m ^−2, and then cured at 50 ° C. for 24 hours. Processing was carried out to obtain a photosensitive material.

[exposure]
The obtained photosensitive material was exposed to ultraviolet rays through a photomask having a mesh pattern (line width 0.01 mm, pitch 0.2 mm).

[Chemical development]
The exposed photosensitive material is subjected to development processing at 25 ° C. for 60 seconds using the following developer (DEV-1), and then subjected to fixing processing at 25 ° C. for 120 seconds using the following fixing solution (FIX-1). went.

(DEV-1)
Pure water 500cm ³
Metol 2g
80 g of anhydrous sodium sulfite
Hydroquinone 4g
4g borax
Sodium thiosulfate 10g
Potassium bromide 0.5g
Water was added to bring the total volume to 1000 cm ³ .

(FIX-1)
Pure water 750cm ³
Sodium thiosulfate 250g
Anhydrous sodium sulfite 15g
Glacial acetic acid 15cm ³
Potash alum 15g
Water was added to bring the total volume to 1000 cm ³ .

[Physical development]
Next, physical development was performed at 30 ° C. for 10 minutes using the following physical developer (PDEV-1), and then washed with tap water for 10 minutes.

(PDEV-1)
Pure water 900cm ³
Citric acid 10g
Trisodium citrate 1g
Ammonia water (28%) 1.5g
Hydroquinone 2.3g
Silver nitrate 0.23g
Water was added to bring the total volume to 1000 cm ³ .

[Electrolytic plating]
After the physical development treatment, electrolytic copper plating treatment was performed at 25 ° C. using the following electrolytic plating solution, followed by washing with water and drying treatment. In addition, the current control in electrolytic copper plating was performed over 3 minutes, 3 minutes for 1 minute and then 12 minutes for 1A. After the completion of the plating treatment, the plate was rinsed with tap water for 10 minutes to carry out a water washing treatment, and dried using a dry air (50 ° C.) until it was in a dry state.

(Electrolytic plating solution)
Copper sulfate (pentahydrate) 200g
50g of sulfuric acid
Sodium chloride 0.1g
Water was added to bring the total volume to 1000 cm ³ .

  After forming the auxiliary metal wiring (auxiliary silver wiring) 26 as described above, as shown in FIG. 1A, trimethylolpropane triacrylate (TMPTA: Kyoeisha) to which a photopolymerization initiator (Lamberti, Esacure KTO 46) is added. Acrylic resin that is a transparent insulating material for the auxiliary metal wiring 26 by spin-coating a 2-acetoxy-1-methoxypropane (PGMEA) solution of Chemical) and irradiating the entire coating film with ultraviolet rays (wavelength 365 nm). Was covered with a transparent insulating layer 30 containing as a main component.

Thereafter, as shown in FIG. 1B, a vacuum in which Ar gas and O ₂ gas are introduced until the surface of the auxiliary metal wiring 26 and the surface of the transparent insulating layer 30 formed in the opening of the auxiliary metal wiring are substantially flush with each other. The surface of the transparent insulating layer 30 was plasma etched in an atmosphere of 1 Pa to form the planarization layer 31 and the auxiliary electrode 11 was formed.

  Thereafter, a polyethylene dioxythiophene-polystyrene sulfonic acid aqueous solution (PEDOT-PSS: made by HC Stark Clevios, Clevios PH, to which dimethyl sulfoxide (DMSO) is added, is formed on the flat surface including the planarizing layer 31 and the auxiliary metal wiring 26. 500) (hereinafter abbreviated as “PEDOT-PSS aqueous solution I”) and spin-coated at 100 ° C. for 20 minutes. Thereby, the lower electrode layer 12 (film thickness 0.2 μm) was formed.

  Next, a PEDOT-PSS aqueous solution having another composition (manufactured by HC Stark Clevios, Clevios P VP.AI4083) (hereinafter abbreviated as “PEDOT-PSS aqueous solution II”) is spin-coated on the lower electrode layer 12. And heat treatment at 100 ° C. for 20 minutes. Thereby, the hole transport layer 13 (film thickness 0.04 μm) was formed.

A composition in which P3HT (manufactured by Merck, licicon SP001) as an electron donating material and PC ₆₁ BM (manufactured by Frontier Carbon, nanom spectra E100H) as an electron accepting material are dissolved in chlorobenzene, a hole transport layer 13 in a dry nitrogen atmosphere. It spin-coated on top and heat-treated at 110 ° C. for 20 minutes. Thereby, a bulk heterojunction photoelectric conversion layer 15 was formed, and the film thickness was 0.2 μm.

On the photoelectric conversion layer 15, lithium fluoride (film thickness: 1 nm) and aluminum (film thickness: 0.4 μm) were continuously vacuum-deposited to form the upper electrode 21. At this time, a shadow mask was used so that the element area was 1.1 cm ² .

  In the organic photoelectric conversion element having the above configuration, PEDOT-PSS of the auxiliary electrode 11 and the lower electrode layer 12 functions as a positive electrode, and aluminum of the upper electrode 21 functions as a negative electrode.

About the solar cell obtained by making it above, the conversion efficiency was measured by irradiating pseudo solar light 80 mW * cm ^<-2 > from the back surface (surface which does not form the lower electrode 12) side of the PEN film support body 10. FIG. Specifically, a current is applied to an organic thin film solar cell by applying a voltage from a source meter (Model 2400 manufactured by Keithley Instruments) while irradiating a light source in which an xenon lamp (Newport 96000) is combined with an air mass filter (Newport 84094). The value was measured. Conversion efficiency was calculated from the obtained current-voltage characteristics using Peccell IV Curve Analyzer (Pexcel Technologies ver. 2.1).

  The conversion efficiency obtained was 2.7%.

(Example 2)
A solar cell was produced in the same manner as in Example 1 except that pentaerythritol triacrylate (PETIA: manufactured by Daicel Cytec) was used as a monomer for the transparent insulating layer 30. The conversion efficiency of the obtained solar cell was 2.5%.

(Example 3)
A solar cell was produced in the same manner as in Example 1 except that 1,6 hexanediol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd.) was used as the monomer for the transparent insulating layer 30. The conversion efficiency of the obtained solar cell was 2.5%.

Example 4
A solar cell was produced in the same manner as in Example 1 except that polyethylene glycol diacrylate (A-600: manufactured by Shin-Nakamura Chemical Co., Ltd.) was used as the monomer for the transparent insulating layer 30. The conversion efficiency of the obtained solar cell was 1.6%.

(Comparative Example 1)
A solar cell was produced in the same manner as in Example 1 except that t-butyl acrylate was used as the monomer of the transparent insulating layer 30. The conversion efficiency of the obtained solar cell was 1.5%.

(Comparative Example 2)
After forming the auxiliary metal wiring in the same manner as in Example 1, a polyethylene film was disposed on the auxiliary metal wiring, and then heated and pressed to form the transparent insulating layer 30 with polyethylene. Plasma etching was performed on the surface of the transparent insulating layer 30 in the same manner as in Example 1, but etching could not be performed until the surface of the auxiliary metal wiring was exposed, and surface conductivity as the auxiliary electrode 11 was not obtained.

(Comparative Example 3)
A solar cell was produced in the same manner as in Example 1 except that the planarizing layer 13 was not formed. The obtained solar cell was short-circuited and battery characteristics were not obtained. When the cross section of the organic thin film solar cell was observed with an electron microscope, a plurality of portions where the auxiliary silver wiring and the upper aluminum electrode were in contact were confirmed.

(Comparative Example 4)
In the photopolymerization of TMPTA, the same procedure as in Example 1 was performed except that the planarization layer 13 was formed by irradiating ultraviolet rays from the PEN substrate back surface (surface on which silver wiring is not formed) and then cleaning with PGMEA. A solar cell was produced. The obtained solar cell was short-circuited, and the battery characteristics were not obtained. When the cross section of the organic thin film solar cell was observed with an electron microscope, a plurality of grooves in which the acrylic resin was not formed were formed along the outer edge of the auxiliary silver wiring. Contact was confirmed.

(Evaluation)
In Table 1, the result evaluated about the etching property in the said Examples 1-4 and Comparative Examples 1-4, the electroconductivity of the surface of a lower electrode layer, and photoelectric conversion efficiency is shown. As for the etching property, the surface smoothness is good and the step between the auxiliary silver wiring and the flattening layer is 200 nm or less. The surface smoothness is good, but the step between the auxiliary silver wiring and the flattening layer is good. Was found where a spot of 500 nm or more was found, and the case where the surface conductivity of the auxiliary electrode could not be obtained due to poor etching or flattening layer formation, or the case where the surface was short-circuited was rated as x. In addition, regarding the conductivity of the surface of the lower electrode layer, the surface resistance of the conductive material of the mesh electrode opening is 150Ω / □ or less, the surface resistance is 150Ω / □ or more and 1000Ω / □ or less, Δ, The case where the surface conductivity was not obtained or the case where the surface was short-circuited was taken as x.

DESCRIPTION OF SYMBOLS 1, 2 Solar cell 10 Support body 11 Auxiliary electrode 12 Lower electrode layer 15 Photoelectric conversion layer 20 Electrode layer 21 Upper electrode 22 Electrode connection wiring 23 External connection terminal 25, 26 Auxiliary metal wiring 28 Alignment mark 30 Transparent insulating layer 31 Flattening layer 32 Insulating partition

Claims (8)

On the support, an auxiliary electrode having an auxiliary metal wiring having a plurality of openings, and a planarization layer made of a transparent resin filled at least in the openings,
A method for producing a solar cell comprising a photoelectric conversion element in which a lower electrode, a photoelectric conversion layer containing an organic material, and an upper electrode are laminated in this order,
Forming the auxiliary metal wiring on the support;
A step of filling the opening with a transparent resin obtained by polymerizing a composition containing a polyfunctional (meth) acrylic monomer and covering the auxiliary metal wiring to form a transparent insulating layer;
Etching the transparent insulating layer until at least part of the surface of the auxiliary metal wiring is exposed and the surface of the transparent insulating layer in the opening is substantially flush with the surface of the auxiliary metal wiring;
Forming the lower electrode on the surface of the transparent insulating layer and the auxiliary metal wiring; and
And a step of sequentially forming the photoelectric conversion layer and the upper electrode on the lower electrode.   The step of forming the transparent insulating layer is characterized in that the transparent insulating layer is formed by applying a coating liquid comprising the composition to the opening and the surface of the auxiliary metal wiring and then photopolymerizing the coating liquid. Item 10. A method for producing a solar cell according to Item 1.     The method for producing a solar cell according to claim 1, wherein the polyfunctional (meth) acrylic monomer does not contain oxygen in a connecting chain that connects between (meth) acrylic groups.   The method for producing a solar cell according to any one of claims 1 to 3, wherein the polyfunctional (meth) acrylic monomer is trifunctional or higher. In the step of forming the transparent insulating layer, the transparent insulating layer has a thickness at which the surface of the transparent insulating layer is positioned higher than the surface of the photoelectric conversion layer formed later above the surface of the auxiliary metal wiring. Forming,
In the step of etching the transparent insulating layer, an insulating partition in which a part of the transparent insulating layer defines at least a part of the formation region of the lower electrode on at least a part of a plane including the surface of the auxiliary metal wiring The method for manufacturing a solar cell according to claim 1, wherein etching is performed so as to remain as follows. Forming the insulating partition so as to surround the formation region of the lower electrode;
In the formation region surrounded by the insulating partition, the lower electrode and the photoelectric conversion layer are sequentially formed,
6. The upper electrode is formed on the photoelectric conversion layer and the insulating partition so that the photoelectric conversion layer is sealed by the upper electrode and the insulating partition. A method for manufacturing a solar cell.   7. The sun according to claim 1, wherein a position detection mark for optically detecting the position of the auxiliary metal wiring is formed on the support simultaneously with the auxiliary metal wiring. Battery manufacturing method. On the support,
An auxiliary electrode having an auxiliary metal wiring having a plurality of openings, and a planarization layer made of a transparent resin filled in at least the openings,
A solar cell including a photoelectric conversion element formed by laminating a lower electrode, a photoelectric conversion layer containing an organic material, and an upper electrode in this order,
The planarizing layer is formed by etching so that the surface of the auxiliary metal wiring is exposed and the surface of the transparent resin in the opening is substantially flush with the surface of the auxiliary metal wiring.
A solar cell, wherein the transparent resin is a resin obtained by polymerizing a composition containing a polyfunctional (meth) acrylic monomer.