JP2011258978A - Organic thin film solar cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic thin film solar cell module in which a plurality of unit cells are arranged in a planar form and connected in series, and which has a simple configuration and can be manufactured by a simple process.SOLUTION: In an organic thin film solar cell module, a plurality of unit cells 10a and 10b are arranged in a planar form and connected in series, the unit cells comprising: a first electrode layer 3 formed on a transparent substrate 2; a photoelectric conversion layer 4 formed on the first electrode layer; and a second electrode layer 5 formed on the photoelectric conversion layer, the photoelectric conversion layer of one unit cell and the photoelectric conversion layer of the other unit cell being formed as a continuous film. Both the distance between the first electrode layer of one unit cell and the first electrode layer of the other unit cell, and the distance between the second electrode layer of one unit cell and the second electrode layer of the other unit cell are larger than the thickness of the photoelectric conversion layer.

Description

  The present invention relates to an organic thin film solar cell module in which a plurality of unit cells are arranged in a plane and connected in series.

  An organic thin film solar cell is a solar cell in which an organic thin film having an electron donating function and an electron accepting function is disposed between two different electrodes, and a manufacturing process compared to an inorganic solar cell typified by silicon or the like. Is easy, and has the advantage that the area can be increased at low cost.

  In the organic thin film solar cell, the electromotive force is determined by the physical properties of the electron donating medium and the electron accepting medium used for the organic thin film. The electromotive force generated between polythiophene, which is a general electron donating material, and fullerene, which is an electron accepting material, is about 0.6V. For example, the electromotive force required when driving a mobile phone is 3.7 V. In order to realize this, it is necessary to connect a plurality of unit cells in series to generate a desired electromotive force.

  As a technique of series connection, when a plurality of unit cells are arranged in a plane, it has been proposed to three-dimensionally connect a back electrode of one unit cell and a transparent electrode of another unit cell ( For example, see Patent Document 1). In this case, in adjacent unit cells, the transparent electrodes, the photoelectric conversion layers, and the back electrodes are separated in space so as to be electrically insulated from each other.

As a method of separating the photoelectric conversion layers of adjacent unit cells in space, a method of partially removing the photoelectric conversion layer after forming it, or a method of forming the photoelectric conversion layer directly in a pattern shape is known. Examples of the method for partially removing the photoelectric conversion layer include a laser scribing method, an etching method, and a wiping method. Moreover, as a method for directly forming the photoelectric conversion layer in a pattern, a vapor deposition method using a metal mask can be used, and a printing method or a discharge method can also be used.
However, such a method complicates the manufacturing process. Furthermore, when the removal of the photoelectric conversion layer is insufficient, the photoelectric conversion layers of adjacent unit cells cannot be electrically insulated. Especially when a low-viscosity coating liquid is used to form the photoelectric conversion layer, the coating liquid spreads and spreads on the non-coated part after coating. The parts may be integrated, and it is difficult to sufficiently remove the photoelectric conversion layer.

On the other hand, Patent Document 2 discloses an organic solar battery in which adjacent unit cells are mutually in the order of stacking the first electrode layer, the photoelectric conversion layer, and the second electrode layer, and are electrically connected in series. A module is disclosed. In this organic solar cell module, if the photoelectric conversion layer is electrically separated, it does not need to be separated in space. This is because the stacking order of the first electrode layer, the photoelectric conversion layer, and the second electrode layer is opposite in adjacent unit cells, and the first electrode layer and the second electrode layer are alternately formed on the same plane of the substrate. Therefore, in order to connect the second electrode layer of one unit cell and the first electrode layer of another unit cell, the photoelectric conversion layer is partially removed to expose the first electrode layer of the other unit cell. This is thought to be because there is no need to let them.
However, in the above organic solar cell module, the first electrode layer and the second electrode layer are alternately formed on the same plane of the substrate, so that the patterned first electrode layer and the patterned second electrode layer are formed respectively. It is necessary to perform the process to be performed on the front substrate and the back substrate, respectively, and the manufacturing process is complicated.

JP-T-2006-511073 JP 2006-237165 A

  The present invention has been made in view of the above problems, and is an organic thin film solar cell module in which a plurality of unit cells are arranged in a plane and connected in series, and has a simple configuration and a simple process. The main object is to provide an organic thin-film solar cell module that can be manufactured in

  In order to achieve the above object, the present invention provides an organic thin film in which a plurality of unit cells are planarly arranged on a transparent substrate, and at least two unit cells among the plurality of unit cells are connected in series. In the solar cell module, the unit cell is formed on the first electrode layer formed on the transparent substrate, the photoelectric conversion layer formed on the first electrode layer, and the photoelectric conversion layer. In the at least two unit cells having a second electrode layer and connected in series, the second electrode layer of one unit cell and the first electrode layer of another unit cell are electrically The photoelectric conversion layer of the one unit cell and the photoelectric conversion layer of the other unit cell are formed as a continuous film, and the first electrode layer of the one unit cell and the above The spacing between the other unit cells and the first electrode layer, and the one Any space between the second electrode layer of the second electrode layer and the other unit cell of the unit cells, to provide an organic thin film solar cell module being greater than the thickness of the photoelectric conversion layer.

  According to the present invention, in at least two unit cells connected in series, the photoelectric conversion layer of one unit cell and the photoelectric conversion layer of another unit cell are formed as a continuous film. Even if the photoelectric conversion layer is not separated in space, the distance between the first electrode layer of one unit cell and the first electrode layer of another unit cell, and the second electrode layer of the one unit cell and other unit By making the space between the cell and the second electrode layer larger than the thickness of the photoelectric conversion layer, the photoelectric conversion layer of each unit cell can be substantially electrically separated. Therefore, it is not necessary to separate the photoelectric conversion layer of each unit cell in space, the structure of the organic thin film solar cell module can be simplified, and the manufacturing process can be simplified.

  In the above invention, the distance between the first electrode layer of the one unit cell and the first electrode layer of the other unit cell, and the second electrode layer and the other unit of the one unit cell. It is preferable that the interval between the second electrode layers of the cell is 20 μm or more. If the above-mentioned interval is within the above range, the photoelectric conversion layer of each unit cell can be sufficiently electrically separated.

  In the present invention, the distance between the first electrode layer of the one unit cell and the first electrode layer of the other unit cell, the second electrode layer of the one unit cell, and the other It is preferable that the interval between the second electrode layers of the unit cell is 1 mm or more. This is because the heat loss is proportional to the movement distance of the electric charge, so that the electrical separation of the photoelectric conversion layer of each unit cell can be made more reliable when the above-mentioned interval is in the above range.

  Furthermore, in the present invention, the photoelectric conversion layer preferably has a surface resistance value of 200Ω / □ or more. This is because, if the surface resistance value of the photoelectric conversion layer is within the above range, it is possible to make it difficult for charges to move in the plane direction between the photoelectric conversion layers of adjacent unit cells.

  In the present invention, a buffer layer is formed between the first electrode layer and the photoelectric conversion layer, and the buffer layer of the one unit cell and the buffer layer of the other unit cell are continuous. And a distance between the first electrode layer of the one unit cell and the first electrode layer of the other unit cell, and the second electrode layer and the other unit of the one unit cell. It is preferable that the interval between the second electrode layers of the cell is larger than the thickness of the buffer layer. In at least two unit cells connected in series, the buffer layer of each unit cell is formed as a continuous film, and even if the buffer layer of each unit cell is not separated by space, the first cell of one unit cell The distance between the electrode layer and the first electrode layer of another unit cell, and the distance between the second electrode layer of one unit cell and the second electrode layer of another unit cell are made larger than the thickness of the buffer layer. Thus, the buffer layer of each unit cell can be substantially electrically separated.

  In the above case, the surface resistance value of the buffer layer is preferably 200Ω / □ or more. This is because if the surface resistance value of the buffer layer is within the above range, it is possible to make it difficult for charges to move in the plane direction between the buffer layers of adjacent unit cells.

  In the present invention, in at least two unit cells connected in series, the photoelectric conversion layer of one unit cell and the photoelectric conversion layer of another unit cell are formed as a continuous film. The module structure can be simplified and the manufacturing process can be simplified.

It is the schematic plan view and sectional drawing which show an example of the organic thin film solar cell module of this invention. It is a schematic plan view which shows the other example of the organic thin film solar cell module of this invention. It is a schematic plan view which shows the other example of the organic thin film solar cell module of this invention. It is a schematic sectional drawing which shows the other example of the organic thin film solar cell module of this invention. It is a schematic sectional drawing which shows the other example of the organic thin film solar cell module of this invention. It is a graph which shows the space | interval between the electrodes in the reference example 2, and the relationship of a solar cell characteristic.

Hereinafter, the organic thin film solar cell module of the present invention will be described in detail.
The organic thin film solar cell module according to the present invention includes an organic thin film solar cell in which a plurality of unit cells are planarly arranged on a transparent substrate, and at least two unit cells among the plurality of unit cells are connected in series. The unit cell includes a first electrode layer formed on the transparent substrate, a photoelectric conversion layer formed on the first electrode layer, and a second electrode formed on the photoelectric conversion layer. In the at least two unit cells having an electrode layer and connected in series, the second electrode layer of one unit cell and the first electrode layer of another unit cell are electrically connected The photoelectric conversion layer of the one unit cell and the photoelectric conversion layer of the other unit cell are formed as a continuous film, and the first electrode layer and the other unit cell of the one unit cell are formed. A distance between the unit cell and the first electrode layer; and Any space between the second electrode layer and the second electrode layer of the other unit cell of the unit cell of is characterized in that greater than a thickness of the photoelectric conversion layer.

The organic thin film solar cell module of the present invention will be described with reference to the drawings.
FIG. 1A is a schematic plan view showing an example of the organic thin film solar cell module of the present invention, and FIG. 1B is a cross-sectional view taken along line AA in FIG. In the organic thin film solar cell module 1, two unit cells 10a and 10b are arranged in a plane on a transparent substrate 2, and these unit cells 10a and 10b are connected in series. Each unit cell 10a, 10b includes a first electrode layer 3 formed on the transparent substrate 2, a photoelectric conversion layer 4 formed on the first electrode layer 3, and a second electrode formed on the photoelectric conversion layer 4. And an electrode layer 5.
The first electrode layer 3 is formed in a stripe shape on the transparent substrate 2, and the first electrode layer 3 of the unit cell 10a and the first electrode layer 3 of the unit cell 10b are arranged so that the stripe pattern is shifted in the long side direction. Has been. The second electrode layer 5 of the unit cell 10a and the first electrode layer 3 of the unit cell 10b are electrically connected by the connecting portion 6.
The photoelectric conversion layer 4 of the unit cell 10a and the photoelectric conversion layer 4 of the unit cell 10b are formed as a continuous film. The distance d1 between the first electrode layer 3 of the unit cell 10a and the first electrode layer 3 of the unit cell 10b, and the distance between the second electrode layer 5 of the unit cell 10a and the second electrode layer 5 of the unit cell 10b. All of d2 are larger than the thickness of the photoelectric conversion layer 4.

Note that “the distance between the first electrode layer of one unit cell and the first electrode layer of another unit cell” refers to the distance between adjacent unit cells among at least two unit cells connected in series. From the end of the first electrode layer in the region where the first electrode layer and the photoelectric conversion layer or buffer layer in the unit cell are in contact, the first electrode layer and the photoelectric conversion layer or buffer layer in the other unit cell The shortest distance among the distances to the end of the first electrode layer in the contact area.
In addition, the “interval between the second electrode layer of one unit cell and the second electrode layer of another unit cell” refers to the interval between adjacent unit cells among at least two unit cells connected in series. From the end of the second electrode layer and connection part in the region where the second electrode layer and connection part in the unit cell are in contact with the photoelectric conversion layer or buffer layer, the second electrode layer and connection part in the other unit cell This is the shortest distance among the distances between the second electrode layer and the end of the connection part in the region where the photoelectric conversion layer or the buffer layer is in contact.

In the organic thin film solar cell module 1 illustrated in FIG. 1B, first, charges are generated in the photoelectric conversion layer 4 by the incident light 11 from the first electrode layer 3. Next, the generated charges (holes) move in the film thickness direction of the photoelectric conversion layer 4 and are taken out to the first electrode layer 3 at the contact interface between the photoelectric conversion layer 4 and the first electrode layer 3. On the other hand, the generated charges (electrons) move in the film thickness direction of the photoelectric conversion layer 4 and are taken out to the second electrode layer 5 at the contact interface between the photoelectric conversion layer 4 and the second electrode layer 5.
At this time, the charges generated in the photoelectric conversion layer move not only in the film thickness direction of the photoelectric conversion layer but also in the surface direction. The ease of movement of charges in the film thickness direction and in the surface direction is considered to be approximately equal. Further, the longer the charge transfer distance, the greater the current resistance loss in the resistance of the photoelectric conversion layer. Therefore, the distance between the first electrode layer of one unit cell and the first electrode layer of another unit cell, and the distance between the second electrode layer of one unit cell and the second electrode layer of another unit cell are If both are larger than the film thickness of the photoelectric conversion layer, the charge easily moves in the film thickness direction of the photoelectric conversion layer between the first electrode layer and the second electrode layer in the unit cell, and the photoelectric conversion of the adjacent unit cell. It is considered difficult to move in the plane direction of the photoelectric conversion layer between the layers. Therefore, even if the photoelectric conversion layer of one unit cell and the photoelectric conversion layer of another unit cell are formed as a continuous film, the photoelectric conversion layer of one unit cell and the photoelectric conversion layer of another unit cell It is substantially electrically separated.

  Thus, in the present invention, in at least two unit cells connected in series, the photoelectric conversion layer of one unit cell and the photoelectric conversion layer of another unit cell are formed as a continuous film, and each unit cell Even if the photoelectric conversion layers of the cells are not separated in space, the distance between the first electrode layer of one unit cell and the first electrode layer of another unit cell, and the second electrode layer of one unit cell and others By making the distance between the unit cell and the second electrode layer larger than the film thickness of the photoelectric conversion layer, the photoelectric conversion layer of each unit cell can be substantially electrically separated. Therefore, it is possible to simplify the structure of the organic thin film solar cell module. In addition, it is not necessary to partially remove the photoelectric conversion layer or form the photoelectric conversion layer directly in a pattern to separate the photoelectric conversion layer of each unit cell in space, which can simplify the manufacturing process. Is possible.

  In addition, since the electromotive force increases as the number of unit cells connected in series increases, it is conceivable to reduce the interval between the unit cells in order to arrange many unit cells on the substrate. In the method of partially removing the photoelectric conversion layer in order to separate the photoelectric conversion layer of each unit cell in space or the method of forming the photoelectric conversion layer directly in a pattern, the interval between adjacent photoelectric conversion layers is narrowed for accuracy. It is difficult to do. In particular, laser scribe method, etching method and wiping method are extremely difficult. On the other hand, in the present invention, since the photoelectric conversion layer of each unit cell is formed as a continuous film, there is no problem as described above.

  Hereinafter, each structure in the organic thin-film solar cell module of this invention is demonstrated.

1. Photoelectric Conversion Layer The photoelectric conversion layer in the present invention is formed between the first electrode layer and the second electrode layer, and in at least two unit cells connected in series, photoelectric conversion of one unit cell The layer and the photoelectric conversion layer of another unit cell are formed as a continuous film. In at least two unit cells connected in series, the thickness of the photoelectric conversion layer is such that the distance between the first electrode layer of one unit cell and the first electrode layer of another unit cell, and one unit cell. It is smaller than the distance between the second electrode layer of the cell and the second electrode layer of another unit cell.
The “photoelectric conversion layer” refers to a member that contributes to charge separation of the organic thin film solar cell and has a function of transporting generated electrons and holes toward electrodes in opposite directions.

  The film thickness of the photoelectric conversion layer is such that the distance between the first electrode layer of one unit cell and the first electrode layer of another unit cell, and the second electrode layer of one unit cell and the second electrode layer of another unit cell. It may be smaller than the distance from the electrode layer, and can be a film thickness generally employed in organic thin film solar cells. Specifically, the thickness of the photoelectric conversion layer can be set within a range of 0.2 nm to 3000 nm, and preferably within a range of 1 nm to 600 nm. This is because if the film thickness is thicker than the above range, the resistance in the photoelectric conversion layer may increase. On the other hand, if the film thickness is thinner than the above range, light may not be sufficiently absorbed.

The surface resistance value of the photoelectric conversion layer is an index of the movement of charges in the in-plane direction of the photoelectric conversion layer. The higher the surface resistance value of the photoelectric conversion layer, the more difficult the charge moves in the in-plane direction of the photoelectric conversion layer. Specifically, the surface resistance value of the photoelectric conversion layer is preferably 200Ω / □ or more, and more preferably 300Ω / □ or more. As described above, the higher the surface resistance value of the photoelectric conversion layer, the more difficult the charge moves in the in-plane direction of the photoelectric conversion layer, so the upper limit of the surface resistance value of the photoelectric conversion layer is not particularly limited.
The surface resistance value is a value measured by a 4-terminal 4-probe method. For example, the surface resistance value can be measured by using a four-terminal four-probe method constant current application method resistivity meter Loresta EP manufactured by Mitsubishi Chemical Analytic Co., Ltd.

  The shape of the photoelectric conversion layer is not particularly limited as long as the photoelectric conversion layer of each unit cell is formed as a continuous film. For example, as illustrated in FIG. 1A and FIG. The shape of 4 may be a rectangle, and as illustrated in FIG. 3, the shape of the photoelectric conversion layer 4 may be a shape having irregularities in the length direction of the photoelectric conversion layer. The shape of the photoelectric conversion layer is the shape of the first electrode layer, the second electrode layer, and the connection portion for electrically connecting the second electrode layer of one unit cell and the first electrode layer of another unit cell. It is appropriately selected according to the arrangement. Especially, it is preferable that the shape of a photoelectric converting layer is a rectangle. This is because the photoelectric conversion layer can be easily formed.

The photoelectric conversion layer may be a single layer having both an electron-accepting function and an electron-donating function (first aspect), or an electron-accepting layer having an electron-accepting function and an electron-donating function. A layer in which an electron donating layer having n is laminated may be used (second embodiment).
Hereinafter, each aspect will be described.

(1) 1st aspect The 1st aspect of the photoelectric converting layer in this invention is a single layer which has both an electron-accepting function and an electron-donating function, and contains an electron-donating material and an electron-accepting material It is. In this photoelectric conversion layer, since charge separation occurs using a pn junction formed in the photoelectric conversion layer, it functions as a photoelectric conversion layer alone.

The electron donating material is not particularly limited as long as it has a function as an electron donor, but it is preferable that the material can be formed by a wet coating method. A polymer material is preferred.
The conductive polymer is a so-called π-conjugated polymer, which is composed of a π-conjugated system in which double bonds or triple bonds containing carbon-carbon or hetero atoms are alternately linked to single bonds, and exhibits semiconducting properties. It is. In the conductive polymer material, π conjugation is developed in the polymer main chain, so that charge transport in the main chain direction is basically advantageous. In addition, since the electron transfer mechanism of the conductive polymer is mainly hopping conduction between molecules by π stacking, it is advantageous not only for the main chain direction of the polymer but also for the charge transport in the film thickness direction of the photoelectric conversion layer. is there. Furthermore, since the conductive polymer material can be easily formed by a wet coating method using a coating solution in which the conductive polymer material is dissolved or dispersed in a solvent, a large-area organic thin film solar cell Can be manufactured at low cost without requiring expensive equipment.

  Examples of the electron-donating conductive polymer material include polyphenylene, polyphenylene vinylene, polysilane, polythiophene, polycarbazole, polyvinyl carbazole, porphyrin, polyacetylene, polypyrrole, polyaniline, polyfluorene, polyvinyl pyrene, polyvinyl anthracene, and derivatives thereof. And copolymers thereof, or phthalocyanine-containing polymers, carbazole-containing polymers, organometallic polymers, and the like.

Among the above, thiophene-fluorene copolymer, polyalkylthiophene, phenylene ethynylene-phenylene vinylene copolymer, phenylene ethynylene-thiophene copolymer, phenylene ethynylene-fluorene copolymer, fluorene-phenylene vinylene copolymer A thiophene-phenylene vinylene copolymer is preferably used. This is because the energy level difference is appropriate for many electron-accepting materials.
For example, a phenylene ethynylene-phenylene vinylene copolymer (Poly [1,4-phenyleneethynylene-1,4- (2,5-dioctadodecyloxyphenylene) -1,4-phenyleneethene-1,2-diyl-1,4- ( 2,5-dioctadodecyloxyphenylene) ethene-1,2-diyl]) is described in detail in Macromolecules, 35, 3825 (2002) and Micromol. Chem. Phys., 202, 2712 (2001).

  Further, the electron-accepting material is not particularly limited as long as it has a function as an electron acceptor, but it is preferable that the material can be formed by a wet coating method. A conductive polymer material is preferable. This is because the conductive polymer material has the advantages as described above.

Examples of the electron-accepting conductive polymer material include polyphenylene vinylene, polyfluorene, and derivatives thereof, and copolymers thereof, or carbon nanotubes, fullerene derivatives, CN group or CF ₃ group-containing polymers, and the like. -CF ₃ substituted polymer, and the like. Specific examples of the polyphenylene vinylene derivative include CN-PPV (Poly [2-Methoxy-5- (2′-ethylhexyloxy) -1,4- (1-cyanovinylene) phenylene]), MEH-CN-PPV (Poly [2 -Methoxy-5- (2′-ethylhexyloxy) -1,4- (1-cyanovinylene) phenylene]) and the like.

  Further, an electron accepting material doped with an electron donating compound, an electron donating material doped with an electron accepting compound, or the like can also be used. Among these, a conductive polymer material doped with an electron donating compound or an electron accepting compound is preferably used. Conductive polymer materials are basically advantageous in charge transport in the direction of the main chain because of the development of π conjugation in the polymer main chain, and are doped with electron-donating compounds and electron-accepting compounds. This is because electric charges are generated in the π-conjugated main chain, and the electrical conductivity can be greatly increased.

Examples of the electron-accepting conductive polymer material doped with the electron-donating compound include the above-described electron-accepting conductive polymer material. As the electron-donating compound to be doped, for example, a Lewis base such as an alkali metal such as Li, K, Ca, or Cs or an alkaline earth metal can be used. The Lewis base acts as an electron donor.
Examples of the electron-donating conductive polymer material doped with the electron-accepting compound include the above-described electron-donating conductive polymer material. As the electron-accepting compound to be doped, for example, a Lewis acid such as FeCl ₃ (III), AlCl ₃ , AlBr ₃ , AsF ₆ or a halogen compound can be used. In addition, Lewis acid acts as an electron acceptor.

  The mixing ratio of the electron-donating material and the electron-accepting material is appropriately adjusted to an optimal mixing ratio depending on the type of material used.

  The method for forming the photoelectric conversion layer is not particularly limited as long as it can be uniformly formed to a predetermined film thickness and a continuous film can be obtained, but a wet coating method is preferably used. This is because if the wet coating method is used, the photoelectric conversion layer can be formed in the air, and the cost can be reduced and the area can be easily increased.

The method for applying the photoelectric conversion layer coating liquid is not particularly limited as long as the photoelectric conversion layer coating liquid can be uniformly applied and a continuous film can be obtained. In particular, as described later, when the first electrode layer is formed by laminating the auxiliary electrode and the transparent electrode, the coating method of the photoelectric conversion layer coating liquid mainly adjusts the thickness according to the coating amount. It is preferable that the method is possible.
The “application amount” means the coating film thickness. The “method capable of adjusting the thickness mainly in accordance with the coating amount” is a method in which the thickness can be controlled mainly by adjusting the coating amount, and parameters other than the coating amount, for example, rotation This excludes a method of controlling the thickness by adjusting the number (centrifugal force) or the like. The “method capable of adjusting the thickness mainly in accordance with the coating amount” may be any method that can control the thickness mainly by adjusting the coating amount (coating film thickness). The coating amount (coating film thickness) can be adjusted by adjusting the coating speed, the discharge amount, the coating gap, and the like. Methods that can adjust the thickness mainly according to the coating amount include, for example, a die coating method, a bead coating method, a bar coating method, a gravure coating method, an ink jet method, a screen printing method, and an offset printing method. Can be mentioned. On the other hand, the spin coating method is not included in the method capable of adjusting the thickness mainly according to the coating amount.
As described above, as a method capable of adjusting the thickness mainly in accordance with the coating amount, for example, a die coating method, a bead coating method, a bar coating method, a gravure coating method, an ink jet method, a screen printing method, an offset printing method. The printing method such as the method can be mentioned. The printing method is suitable for increasing the area of the organic thin film solar cell.

After application of the coating liquid for photoelectric conversion layer, a drying treatment for drying the formed coating film may be performed. It is because productivity can be improved by removing the solvent etc. which are contained in the coating liquid for photoelectric conversion layers at an early stage.
As a drying method, for example, a general method such as heat drying, air drying, vacuum drying, infrared heat drying, or the like can be used.

(2) Second Aspect In the second aspect of the photoelectric conversion layer in the present invention, an electron accepting layer having an electron accepting function and an electron donating layer having an electron donating function are laminated. Hereinafter, the electron-accepting layer and the electron-donating layer will be described.

(Electron-accepting layer)
The electron-accepting layer used in this embodiment has an electron-accepting function and contains an electron-accepting material.

  The electron-accepting material is not particularly limited as long as it has a function as an electron acceptor, but is preferably a material that can be formed into a film by a wet coating method. A polymer material is preferred. This is because the conductive polymer material has the advantages as described above. Specific examples include the same electron-accepting conductive polymer materials used for the photoelectric conversion layer of the first aspect.

  As the film thickness of the electron-accepting layer, it is sufficient that the film thickness of the photoelectric conversion layer in which the electron-accepting layer and the electron-donating layer are laminated satisfies the above-described film thickness of the photoelectric conversion layer. , 0.1 nm to 1500 nm, and preferably 1 nm to 300 nm. This is because if the film thickness is larger than the above range, the resistance in the electron-accepting layer may be increased, and if the film thickness is smaller than the above range, light may not be sufficiently absorbed.

  The method for forming the electron-accepting layer can be the same as the method for forming the photoelectric conversion layer of the first aspect.

(Electron donating layer)
The electron donating layer used in the present invention has an electron donating function and contains an electron donating material.

  The electron donating material is not particularly limited as long as it has a function as an electron donor, but it is preferable that the material can be formed by a wet coating method. A polymer material is preferred. This is because the conductive polymer material has the advantages as described above. Specific examples include the same electron donating conductive polymer materials used for the photoelectric conversion layer of the first aspect.

  As the film thickness of the electron donating layer, it is sufficient that the film thickness of the photoelectric conversion layer in which the electron accepting layer and the electron donating layer are laminated satisfies the above film thickness of the photoelectric conversion layer. , 0.1 nm to 1500 nm, and preferably 1 nm to 300 nm. This is because if the film thickness is thicker than the above range, the resistance in the electron donating layer may be increased, and if the film thickness is thinner than the above range, light may not be sufficiently absorbed.

  The method for forming the electron donating layer can be the same as the method for forming the photoelectric conversion layer of the first aspect.

2. First electrode layer The first electrode layer in the present invention is formed on a transparent substrate, and in at least two unit cells connected in series, the first electrode layer of one unit cell and other units The distance between the cell and the first electrode layer is larger than the thickness of the photoelectric conversion layer. In at least two unit cells connected in series, the first electrode layer of one unit cell is electrically connected to the second electrode layer of another unit cell. The first electrode layer is usually an electrode for extracting holes generated in the photoelectric conversion layer (hole extraction electrode). In the present invention, since the first electrode layer side is the light receiving surface, the first electrode layer has transparency.

The interval between the first electrode layer of one unit cell and the first electrode layer of another unit cell may be larger than the thickness of the photoelectric conversion layer. Here, the heat loss is proportional to the movement distance of the charges. The longer the charge travel distance, the greater the heat loss. Accordingly, the larger the distance between the first electrode layer of one unit cell and the first electrode layer of the other unit cell, the more easily the charge moving in the surface direction of the photoelectric conversion layer changes to heat, and the photoelectric conversion of each unit cell. The electrical separation of the layers can be made more reliable.
Specifically, the distance between the first electrode layer of one unit cell and the first electrode layer of another unit cell is preferably 20 μm or more. Especially, it is preferable that it is about 20 micrometers-100 micrometers from a viewpoint of the characteristic (short circuit current, open circuit voltage) of a solar cell. Further, as described above, from the viewpoint of insulating properties, the interval is preferably as large as possible, and more preferably 1 mm or more. In this case, if the interval between the first electrode layer of one unit cell and the first electrode layer of another unit cell is wide, the number of unit cells that can be arranged on the transparent substrate is reduced. It is about 10 mm. In addition, the said space | interval can be measured with an optical microscope.

The first electrode layer is not particularly limited as long as it is an electrode on the light receiving surface side, and may be a transparent electrode, or a laminate of a transparent electrode and a patterned auxiliary electrode. May be.
As illustrated in FIG. 4, when the first electrode layer 3 is a laminate of the patterned auxiliary electrode 3a and the transparent electrode 3b, even if the sheet resistance of the transparent electrode is relatively high, By making the sheet resistance of the auxiliary electrode sufficiently low, the resistance of the first electrode layer as a whole can be reduced. Therefore, the generated power can be collected efficiently.
Hereinafter, the transparent electrode and the auxiliary electrode will be described.

(1) Transparent electrode The transparent electrode used in the present invention is formed on a transparent substrate.

  The constituent material of the transparent electrode is not particularly limited as long as it has conductivity and transparency. In—Zn—O (IZO), In—Sn—O (ITO), ZnO—Al, Zn—Sn— O etc. can be mentioned. Among them, it is preferable to select appropriately considering the work function of the constituent material of the second electrode layer described later. For example, when the constituent material of the second electrode layer is a material having a low work function, the constituent material of the transparent electrode is preferably a material having a high work function. ITO is preferably used as a material having conductivity and transparency and a high work function.

The total light transmittance of the transparent electrode is preferably 85% or more, more preferably 90% or more, and particularly preferably 92% or more. This is because when the total light transmittance of the transparent electrode is within the above range, light can be sufficiently transmitted through the transparent electrode and light can be efficiently absorbed by the photoelectric conversion layer.
The total light transmittance is a value measured using an SM color computer (model number: SM-C) manufactured by Suga Test Instruments Co., Ltd. in the visible light region.

The sheet resistance of the transparent electrode is preferably 20Ω / □ or less, more preferably 10Ω / □ or less, and particularly preferably 5Ω / □ or less. This is because if the sheet resistance is larger than the above range, the generated charge may not be sufficiently transmitted to the external circuit.
In addition, the said sheet resistance is measured based on JIS R1637 (Resistance test method of fine ceramics thin film: Measurement method by 4 probe method) using a surface resistance meter (Loresta MCP: Four-terminal probe) manufactured by Mitsubishi Chemical Corporation. It is the value.

The transparent electrode may be a single layer or may be laminated using materials having different work functions.
As the film thickness of this transparent electrode, the film thickness is preferably in the range of 0.1 nm to 500 nm in the case of a single layer, and the total film thickness is preferably in the range of 0.1 nm to 500 nm. It is preferable to be within the range. If the film thickness is less than the above range, the sheet resistance of the transparent electrode becomes too large, and the generated charge may not be sufficiently transmitted to the external circuit. On the other hand, if the film thickness is thicker than the above range, the total light transmittance This is because there is a possibility that the photoelectric conversion efficiency is lowered.

The transparent electrode of each unit cell is separated by a space, and the transparent electrode is formed in a pattern on a transparent substrate. The arrangement of the transparent electrode pattern is not particularly limited as long as the second electrode layer of one unit cell and the first electrode layer of another unit cell can be electrically connected to each other. The connection portion and the photoelectric conversion layer are appropriately selected according to the shape and arrangement.
As a method for forming the transparent electrode, a general electrode forming method can be used.

(2) Auxiliary electrode The auxiliary electrode used for this invention is formed in a pattern form on a transparent substrate. The auxiliary electrode usually has a lower resistance value than the transparent electrode.

  A metal is usually used as a material for forming the auxiliary electrode. Examples of the metal used for the auxiliary electrode include aluminum (Al), gold (Au), silver (Ag), cobalt (Co), nickel (Ni), platinum (Pt), copper (Cu), and titanium (Ti). And conductive metals such as iron (Fe), stainless steel, aluminum alloy, copper alloy, titanium alloy, iron-nickel alloy and nickel-chromium alloy (Ni-Cr). Among the conductive metals described above, those having a relatively low electrical resistance value are preferred. Examples of such a conductive metal include Al, Au, Ag, and Cu.

  In addition, the auxiliary electrode may be a single layer made of the conductive metal as described above, and the conductive metal layer and the contact layer are appropriately laminated in order to improve the adhesion with the transparent substrate or the transparent electrode. It may be a thing. Examples of the material for forming the contact layer include nickel (Ni), chromium (Cr), nickel chromium (Ni—Cr), titanium (Ti), and tantalum (Ta). The contact layer is laminated on the conductive metal layer in order to obtain adhesion between the desired auxiliary electrode and the transparent substrate or transparent electrode, and may be laminated only on one side of the conductive metal layer. It may be laminated on both sides of the layer.

  Further, a preferred metal may be selected according to the work function of the material for forming the second electrode layer. For example, when the work function of the material for forming the second electrode layer is taken into consideration, the first electrode layer is a hole extraction electrode, and therefore, the metal used for the auxiliary electrode preferably has a high work function. . Specifically, Al is preferably used.

  The shape of the auxiliary electrode is not particularly limited as long as it is a pattern, and is appropriately selected depending on desired conductivity, permeability, strength, and the like. For example, the auxiliary electrode may have a mesh-shaped mesh portion and a frame portion arranged around the mesh portion, or may be formed of a mesh-shaped mesh portion.

  When the auxiliary electrode has a mesh portion and a frame portion, the mesh portion and the frame portion may be arranged, for example, when the auxiliary electrode is rectangular, the frame portion may be arranged so as to surround four sides of the mesh portion. Further, it may be arranged so as to surround three sides of the mesh part, may be arranged so as to surround two sides of the mesh part, or may be arranged on one side of the mesh part. Especially, it is preferable that the frame part is arrange | positioned so that the four sides or three sides of a mesh part may be enclosed. This is because current can be collected efficiently.

  The shape of the mesh portion is not particularly limited as long as it is a mesh shape, and is appropriately selected depending on desired conductivity, permeability, strength, and the like. For example, a polygon such as a triangle, a quadrangle, and a hexagon, a circular lattice, and the like can be given. In addition, a polygon or circular “lattice shape” refers to a shape in which polygons or circles are periodically arranged. As the polygonal or circular lattice shape, for example, polygonal openings may be arranged in a straight line or zigzag.

  Especially, it is preferable that the shape of a mesh part is a hexagonal lattice shape or a parallelogram lattice shape. This is because the current flowing through the mesh portion can be prevented from being concentrated locally. In the case of a hexagonal lattice, it is particularly preferable that the hexagonal openings are arranged in a zigzag (so-called honeycomb shape). On the other hand, in the case of a parallelogram lattice, the acute angle of the parallelogram is preferably within the range of 40 ° to 80 °, more preferably within the range of 50 ° to 70 °, and even more preferably 55 ° to 65 °. Within the range of °.

  Since the auxiliary electrode itself basically does not transmit light, light enters the photoelectric conversion layer from the opening of the mesh portion of the auxiliary electrode. Therefore, it is preferable that the opening of the mesh part of the auxiliary electrode is relatively large. Specifically, the ratio of the openings in the mesh portion of the auxiliary electrode is preferably about 50% to 98%, more preferably in the range of 70% to 98%, and still more preferably in the range of 80% to 98%. Within range.

The pitch of the openings of the mesh portion of the auxiliary electrode and the line width of the mesh portion are appropriately selected according to the area of the entire auxiliary electrode and the like.
The line width of the frame portion is appropriately selected according to the area of the entire auxiliary electrode.

  The thickness of the auxiliary electrode is not limited as long as the short circuit does not occur between the first electrode layer and the second electrode layer, and the thickness of the photoelectric conversion layer, the hole extraction layer, the electron extraction layer, etc. It is selected as appropriate. Specifically, when the total film thickness of the layers (photoelectric conversion layer, hole extraction layer, electron extraction layer) formed between the first electrode layer and the second electrode layer is 1, the thickness of the auxiliary electrode is It is preferably 5 or less, more preferably 3 or less, further 2 or less, particularly preferably 1.5 or less, and most preferably 1 or less. This is because if the thickness of the auxiliary electrode is larger than the above range, a short circuit may occur between the electrodes. More specifically, the thickness of the auxiliary electrode is preferably in the range of 100 nm to 1000 nm, more preferably in the range of 200 nm to 800 nm, further in the range of 200 nm to 500 nm, and particularly in the range of 200 nm to 400 nm. It is preferable. This is because if the thickness of the auxiliary electrode is thinner than the above range, the sheet resistance of the auxiliary electrode may become too large. Moreover, it is because there exists a possibility that a short circuit may arise between electrodes when the thickness of an auxiliary electrode is thicker than the said range.

Especially, when forming a photoelectric converting layer on the 1st electrode layer by the method which can adjust thickness mainly according to a coating amount, it is preferable that the thickness of an auxiliary electrode exists in the range of 200 nm-300 nm. . When the photoelectric conversion layer is formed on the first electrode layer by a method capable of adjusting the thickness mainly according to the coating amount, if the thickness of the auxiliary electrode is larger than the above range, the mesh portion of the auxiliary electrode or It becomes difficult to cover the edge of the frame part, and a short circuit is likely to occur between the electrodes. Further, if the thickness of the auxiliary electrode is larger than the above range, the photoelectric conversion layer may be formed thicker than the desired thickness due to surface tension. If the thickness of the photoelectric conversion layer is too thick, it exceeds the electron diffusion length and the hole diffusion length, and the conversion efficiency decreases. It is preferable to adjust the thickness of the auxiliary electrode so that the photoelectric conversion layer is not formed thicker than desired due to surface tension. In particular, since it is known that the distance that holes and electrons can move in the photoelectric conversion layer is about 100 nm, the auxiliary electrode is formed so that the photoelectric conversion layer is not formed thicker than the desired thickness due to surface tension. It is preferable to adjust the thickness.
On the other hand, when the photoelectric conversion layer is formed by, for example, a spin coating method, a uniform film is formed by centrifugal force, so that the edge of the auxiliary electrode can be covered even if the auxiliary electrode is relatively thick. In the case of the spin coating method, the thickness can be adjusted by the number of rotations, so that a uniform film can be obtained even if the auxiliary electrode is relatively thick.
Therefore, when the photoelectric conversion layer is formed mainly by a method capable of adjusting the thickness according to the coating amount, the above range is particularly preferable.

The sheet resistance of the auxiliary electrode may be lower than that of the transparent electrode. Specifically, the sheet resistance of the auxiliary electrode is preferably 5Ω / □ or less, more preferably 3Ω / □ or less, more preferably 1Ω / □ or less, particularly preferably 0.5Ω / □ or less, and 0.1Ω. Most preferably, it is less than / □. This is because if the sheet resistance of the auxiliary electrode is larger than the above range, desired power generation efficiency may not be obtained.
In addition, the said sheet resistance is measured based on JIS R1637 (Resistance test method of fine ceramics thin film: Measurement method by 4 probe method) using a surface resistance meter (Loresta MCP: Four-terminal probe) manufactured by Mitsubishi Chemical Corporation. It is the value.

  The auxiliary electrode may be formed on the transparent substrate in the order of the auxiliary electrode and the transparent electrode, or on the transparent substrate in the order of the transparent electrode and the auxiliary electrode. Especially, it is preferable to laminate | stack in order of the auxiliary electrode and the transparent electrode on the transparent substrate. This is because the larger the contact area between the transparent electrode, the photoelectric conversion layer, the hole extraction layer, and the like, the better the interface bondability and the higher the hole transfer efficiency.

  The method for forming the auxiliary electrode is not particularly limited, and examples thereof include a method of forming a metal thin film on the entire surface and then patterning it into a mesh shape, a method of directly forming a mesh-like conductor, and the like. These methods are appropriately selected depending on the auxiliary electrode forming material, configuration, and the like.

The method for forming the metal thin film is preferably a vacuum film forming method such as a vacuum deposition method, a sputtering method, or an ion plating method. That is, the auxiliary electrode is preferably a metal thin film formed by a vacuum film forming method. The metal species formed by the vacuum film formation method has less inclusions than the plating film and can reduce the specific resistance, and can also reduce the specific resistance as compared with those formed using Ag paste or the like. Further, a vacuum film formation method is also suitable as a method for forming a metal thin film having a thickness of 1 μm or less, preferably 500 nm or less, with a precise thickness and a uniform thickness.
The method for patterning the metal thin film is not particularly limited as long as it can be accurately formed into a desired pattern, and examples thereof include a photoetching method.

3. Second electrode layer The second electrode layer used in the present invention is an electrode facing the first electrode layer, and in at least two unit cells connected in series, the second electrode layer of one unit cell and The interval between the other unit cells and the second electrode layer is larger than the thickness of the photoelectric conversion layer. In at least two unit cells connected in series, the second electrode layer of one unit cell is electrically connected to the first electrode layer of another unit cell. The second electrode layer is usually an electrode (electron extraction electrode) for extracting electrons generated in the photoelectric conversion layer. In the present invention, since the first electrode layer side is the light receiving surface, the second electrode layer may not have transparency.

The distance between the second electrode layer of one unit cell and the second electrode layer of another unit cell may be larger than the thickness of the photoelectric conversion layer. As described above, since the heat loss is proportional to the charge transfer distance, the charge transfer distance increases as the distance between the second electrode layer of one unit cell and the second electrode layer of another unit cell increases. Further, heat loss is increased, and electrical separation of the photoelectric conversion layer of each unit cell can be further ensured.
In addition, about the space | interval of the 2nd electrode layer of one unit cell, and the 2nd electrode layer of another unit cell, the 1st electrode layer of the above-mentioned 1 unit cell and the 1st electrode layer of another unit cell are mentioned. It can be similar to the interval. The interval between the second electrode layer of one unit cell and the second electrode layer of another unit cell is the same as the interval between the first electrode layer of one unit cell and the first electrode layer of another unit cell. Or may be different.

  The material for forming the second electrode layer is not particularly limited as long as it has conductivity. However, since the second electrode layer is an electron extraction electrode, it preferably has a low work function. Specific examples of the material having a low work function include Li, In, Al, Ca, Mg, Sm, Tb, Yb, Zr, and LiF.

The second electrode layer may be a single layer or may be laminated using materials having different work functions.
The film thickness of the second electrode layer is a single layer, and when it is composed of a plurality of layers, the total film thickness of each layer is within the range of 0.1 nm to 500 nm, and in particular, 1 nm to 300 nm. It is preferable to be within the range. When the film thickness is thinner than the above range, the sheet resistance of the second electrode layer becomes too large, and the generated charge may not be sufficiently transmitted to the external circuit.

The second electrode layer of each unit cell is separated by a space, and the second electrode layer is formed in a pattern on the photoelectric conversion layer. The arrangement of the pattern of the second electrode layer is not particularly limited as long as the second electrode layer of one unit cell and the first electrode layer of another unit cell can be electrically connected. It is suitably selected according to the shape and arrangement of the electrode layer, the connection part, and the photoelectric conversion layer.
As a method for forming the second electrode layer, a general electrode forming method can be used.

  In order to electrically connect the second electrode layer of one unit cell and the first electrode layer of another unit cell, a connection portion 6 is formed as illustrated in FIG. 1A, FIG. 2 and FIG. If it is, the connecting portion is formed to have a predetermined shape. The shape of the connecting portion is not particularly limited as long as it is a shape that can electrically connect the second electrode layer of one unit cell and the first electrode layer of another unit cell, It is suitably selected according to the shape and arrangement of the first electrode layer, the second electrode layer, and the photoelectric conversion layer.

The material for forming the connection portion may be the same as or different from the material for forming the second electrode layer, but is usually the same as the material for forming the second electrode layer. This is because the second electrode layer and the connection portion can be formed at the same time.
The method for forming the connection portion is not particularly limited as long as the connection portion can be formed in a pattern, and for example, a vapor deposition method using a metal mask can be employed.

4). Transparent substrate The transparent substrate used in the present invention is not particularly limited. For example, a transparent rigid material having no flexibility such as quartz glass, Pyrex (registered trademark), synthetic quartz plate, or a transparent resin film, Examples thereof include a transparent flexible material having flexibility such as an optical resin plate.

  Among the above, the transparent substrate is preferably a flexible material such as a transparent resin film. Transparent resin films are excellent in processability, and are useful in the realization of organic thin-film solar cells that reduce manufacturing costs, reduce weight, and are difficult to break, and expand their applicability to various applications such as application to curved surfaces. is there.

5). Buffer Layer In the present invention, a buffer layer may be formed between the first electrode layer and the photoelectric conversion layer or between the photoelectric conversion layer and the second electrode layer. The buffer layer is a layer provided so that the charge can be easily taken out from the photoelectric conversion layer to the first electrode layer or the second electrode layer. Since the charge extraction efficiency from the photoelectric conversion layer to the first electrode layer or the second electrode layer is increased by forming the buffer layer, the photoelectric conversion efficiency can be improved.

  In this case, in at least two unit cells connected in series, the buffer layer of one unit cell and the buffer layer of another unit cell are formed as a continuous film, and the first electrode layer of one unit cell and the other The distance between the unit cell and the first electrode layer, and the distance between the second electrode layer of one unit cell and the second electrode layer of another unit cell may be larger than the thickness of the buffer layer. preferable. Similar to the photoelectric conversion layer described above, the buffer layer of each unit cell is formed as a continuous film, and the first electrode layer of one unit cell and the other are not separated even if the buffer layer of each unit cell is separated in space. By making the interval between the first electrode layer of the unit cell and the second electrode layer of one unit cell and the second electrode layer of the other unit cell larger than the thickness of the buffer layer, The buffer layer of the unit cell can be substantially electrically separated.

  The thickness of the buffer layer includes the distance between the first electrode layer of one unit cell and the first electrode layer of another unit cell, and the second electrode layer of one unit cell and the second electrode of another unit cell. It is sufficient that it is smaller than the distance between the layers, and specifically, it is preferably in the range of 10 nm to 200 nm.

The surface resistance value of the buffer layer is an index of the movement of charges in the in-plane direction of the buffer layer. The higher the surface resistance value of the buffer layer, the more difficult the charge moves in the in-plane direction of the buffer layer. Specifically, the surface resistance value of the buffer layer is preferably 200Ω / □ or more, and more preferably 300Ω / □ or more. As described above, the higher the surface resistance value of the buffer layer, the more difficult the charge moves in the in-plane direction of the buffer layer, so the upper limit of the surface resistance value of the buffer layer is not particularly limited.
In addition, about the measuring method of the said surface resistance value, it is the same as that of the method described in the term of the said photoelectric converting layer.

  The shape of the buffer layer is not particularly limited as long as the buffer layer of each unit cell is formed as a continuous film, and the second electrode layer of one unit cell and the first electrode layer of another unit cell Are appropriately selected according to the shape and arrangement of the first electrode layer, the second electrode layer, and the connection portion for electrically connecting the two.

The buffer layer may be a hole extraction layer or an electron extraction layer.
Hereinafter, the hole extraction layer and the electron extraction layer will be described.

(1) Hole Extraction Layer In the present invention, a hole extraction layer 7 is formed between the first electrode layer 3 (hole extraction electrode) and the photoelectric conversion layer 4 as illustrated in FIG. It is preferable. The hole extraction layer is a layer provided so that holes can be easily extracted from the photoelectric conversion layer to the hole extraction electrode. Thereby, since the hole extraction efficiency from the photoelectric conversion layer to the hole extraction electrode is increased, the photoelectric conversion efficiency can be improved.

  The material used for the hole extraction layer is not particularly limited as long as it is a material that stabilizes the extraction of holes from the photoelectric conversion layer to the hole extraction electrode. Specifically, doped polyaniline, polyphenylene vinylene, polythiophene, polypyrrole, polyparaphenylene, polyacetylene, conductive organic compounds such as triphenyldiamine (TPD), or electron donation such as tetrathiofulvalene, tetramethylphenylenediamine, etc. An organic material that forms a charge transfer complex composed of an organic compound and an electron-accepting compound such as tetracyanoquinodimethane and tetracyanoethylene. Among these, polyethylenedioxythiophene (PEDOT) and triphenyldiamine (TPD) are particularly preferably used.

(2) Electron Extraction Layer In the present invention, an electron extraction layer may be formed between the photoelectric conversion layer and the second electrode layer (electron extraction electrode). The electron extraction layer is a layer provided so that electrons can be easily extracted from the photoelectric conversion layer to the electron extraction electrode. Thereby, since the electron extraction efficiency from the photoelectric conversion layer to the electron extraction electrode is increased, the photoelectric conversion efficiency can be improved.

  The material used for the electron extraction layer is not particularly limited as long as it is a material that stabilizes the extraction of electrons from the photoelectric conversion layer to the electron extraction electrode. Specifically, doped polyaniline, polyphenylene vinylene, polythiophene, polypyrrole, polyparaphenylene, polyacetylene, conductive organic compounds such as triphenyldiamine (TPD), or electron donation such as tetrathiofulvalene, tetramethylphenylenediamine, etc. An organic material that forms a charge transfer complex composed of an organic compound and an electron-accepting compound such as tetracyanoquinodimethane and tetracyanoethylene. Moreover, the metal dope layer with an alkali metal or alkaline-earth metal is mentioned. Suitable materials include bathocuproin (BCP) or bathophenantrone (Bphen) and metal doped layers such as Li, Cs, Ba, Sr.

6). Unit Cell In the present invention, a plurality of unit cells are arranged in a plane on a transparent substrate, and at least two unit cells among the plurality of unit cells are connected in series.
The unit cells may be connected as long as at least two unit cells among the plurality of unit cells are connected in series, may be only in series, or may be a combination of series and parallel. For example, all the unit cells may be connected in series, or a plurality of units in which at least two unit cells are connected in series may be arranged, and at least two unit cells are connected in series. Things may be connected in parallel. Specifically, when four unit cells are arranged in a plane on a transparent substrate, four unit cells may be connected in series, or two unit cells may be connected in series. In the meantime, it is not necessary to connect them, and two unit cells may be connected in series and connected in parallel.

7). Other Configurations The organic thin film solar cell module of the present invention may have constituent members to be described later as necessary in addition to the constituent members described above. For example, the organic thin film solar cell module of the present invention has functions such as a protective sheet, a filler layer, a barrier layer, a protective hard coat layer, a strength support layer, an antifouling layer, a high light reflection layer, a light containment layer, and a sealing material layer. It may have a layer. In addition, an adhesive layer may be formed between the functional layers depending on the layer configuration.
These functional layers can be the same as those described in JP-A-2007-73717.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

Hereinafter, the present invention will be specifically described with reference to examples.
[Example 1]
ITO electrodes were formed in a stripe shape having a length of 250 mm and a width of 20 mm on a PET film having a size of 300 mm □ and a thickness of 125 μm by a sputtering method. At this time, the ITO electrode pattern was arranged at an interval of 1 mm so that the length direction of the ITO electrode pattern was the same as the width direction of the PET film.

Next, after applying a conductive polymer solution (poly- (3,4-ethylenedioxythiophene) dispersion) by the die coating method with the same width as the ITO electrode pattern, drying is performed at 100 ° C. for 10 minutes. Thus, a buffer layer having a surface resistance value of 600Ω / □ and a thickness of 50 nm was formed.
Next, polythiophene (P3HT: poly (3-hexylthiophene-2,5-diyl)) and C60PCBM ([6,6] -phenyl-C61-butyric acid mettric ester; manufactured by Nano-C) are dissolved in bromobenzene. And a coating liquid for a photoelectric conversion layer having a solid content concentration of 1.4 wt% was prepared. Next, after coating this photoelectric conversion layer coating solution by the die coating method with the same width as the buffer layer, it was dried at 100 ° C. for 10 minutes to form a photoelectric conversion layer having a surface resistance of 1 MΩ / □ or more and a thickness of 200 nm. Formed.

  Next, the same shape as the first electrode layer, and a shape in which an arbitrary position on the photoelectric conversion layer and the exposed portion of the ITO electrode located at the end of the adjacent unit cell are continuously connected. Calcium and aluminum were formed by a vacuum vapor deposition method using a vapor deposition mask that also serves as a second electrode layer and a connection portion.

  Thus, an organic thin film solar cell module in which four unit cells were connected in series on a single substrate was produced. When four unit cells are arranged, the open circuit voltage value is about 2.4V.

[Example 2]
A single substrate is formed in the same manner as in Example 1 except that the thickness of the buffer layer is 100 nm, the surface resistance value is 300 Ω / □, the thickness of the photoelectric conversion layer is 100 nm, and the surface resistance value is 2 MΩ / □. An organic thin-film solar battery module in which four unit cells are connected in series was produced. When four unit cells are arranged, the open circuit voltage value is about 2.4V.

[Reference Example 1]
A semiconductor layer is formed on a substrate, a source electrode and a drain electrode are formed on the semiconductor layer, an insulating film is formed between the source electrode and the drain electrode, and a gate electrode is formed on the insulating film, whereby an organic transistor is manufactured. did. For the semiconductor layer, the same polythiophene-based material as that used for the buffer layer or photoelectric conversion layer of Example 1 was used. The length of the source electrode and the drain electrode was 1 mm, and the distance between the source electrode and the drain electrode was 20 μm. When the transistor characteristics were evaluated, the value of off-state current was sufficiently low, and was lower than 10 ⁻⁷ A, which is a practical level.
Thus, it was confirmed that the buffer layer and the photoelectric conversion layer were electrically separated if the distance between the electrodes was at least 20 μm apart.

[Reference Example 2]
The relationship between the distance between the electrodes and the characteristics of the solar cell (short-circuit current, open-circuit voltage) was examined by simulation. At this time, the width of the electrode pattern was set to 10 mm and the length was set to 15 cm, and the distance between the electrodes was changed to perform the simulation. The simulation results are shown in FIGS. 6 (a) and 6 (b). FIG. 6 (b) is an enlarged view of FIG. 6 (a).
Thereby, when the space | interval between electrodes was 20 micrometers-100 micrometers, it confirmed that the characteristic (short circuit current density x open circuit voltage) of a solar cell became high.

DESCRIPTION OF SYMBOLS 1 ... Organic thin film solar cell module 2 ... Transparent substrate 3 ... 1st electrode layer 3a ... Auxiliary electrode 3b ... Transparent electrode 4 ... Photoelectric conversion layer 5 ... 2nd electrode layer 6 ... Connection part 7 ... Hole extraction layer 10a, 10b, 10c, 10d: Unit cell d1: Distance between the first electrode layer of one unit cell and the first electrode layer of another unit cell d2: Second electrode layer of one unit cell and second electrode of another unit cell Spacing with layer

Claims (6)

A plurality of unit cells are arranged in a plane on a transparent substrate, and an organic thin film solar cell module in which at least two unit cells among the plurality of unit cells are connected in series,
The unit cell is formed on the transparent substrate, a first electrode layer in which a transparent electrode and a patterned auxiliary electrode are stacked, a photoelectric conversion layer formed on the first electrode layer, and the photoelectric conversion layer A second electrode layer formed thereon,
In the at least two unit cells connected in series, the second electrode layer of one unit cell and the first electrode layer of another unit cell are electrically connected,
The photoelectric conversion layer of the one unit cell and the photoelectric conversion layer of the other unit cell are formed as a continuous film,
The distance between the first electrode layer of the one unit cell and the first electrode layer of the other unit cell, and the second electrode layer of the one unit cell and the second of the other unit cell. An organic thin-film solar cell module, wherein the distance from the electrode layer is larger than the thickness of the photoelectric conversion layer.   The distance between the first electrode layer of the one unit cell and the first electrode layer of the other unit cell, and the second electrode layer of the one unit cell and the second of the other unit cell. 2. The organic thin-film solar cell module according to claim 1, wherein an interval between each electrode layer is 20 μm or more.   The distance between the first electrode layer of the one unit cell and the first electrode layer of the other unit cell, and the second electrode layer of the one unit cell and the second of the other unit cell. The organic thin film solar cell module according to claim 2, wherein the distance from the electrode layer is 1 mm or more.   The surface resistance value of the said photoelectric converting layer is 200 ohms / square or more, The organic thin film solar cell module in any one of Claim 1 to 3 characterized by the above-mentioned.   A buffer layer is formed between the first electrode layer and the photoelectric conversion layer, the buffer layer of the one unit cell and the buffer layer of the other unit cell are formed as a continuous film, The distance between the first electrode layer of one unit cell and the first electrode layer of the other unit cell, and the second electrode layer of the one unit cell and the second electrode of the other unit cell 5. The organic thin-film solar cell module according to claim 1, wherein the distance between the layers is larger than the thickness of the buffer layer.   6. The organic thin film solar cell module according to claim 5, wherein the buffer layer has a surface resistance value of 200 Ω / □ or more.

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