JPWO2012172878A1 - Organic thin film solar cell and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce an organic thin film solar cell having stable performance. In one aspect of the present invention, a pair of first and second electrode layers 10 and 20 that are paired with each other and a first conductivity type formed on one surface of the electrode are provided. A thin film solar cell 100 including a contact layer 22 and a photoelectric conversion layer 100 disposed in contact with the first conductivity type contact layer 22 is provided. The photoelectric conversion layer 100 includes a p-type organic polymer region 102 and an n-type organic low-molecular region 104, and the p-type organic polymer region 102 and the n-type organic low-molecular region 104 have a thickness D1 of the photoelectric conversion layer 100. The penetrating structure is a structure that extends in any direction across the surface.

Description

  The present invention relates to an organic thin film solar cell and a method for manufacturing the same. More specifically, the present invention relates to an organic thin film solar cell of a photoelectric conversion layer having a penetrating structure and a method for producing the same.

  In recent years, organic solar cells, which are solar cells using organic materials, have been developed. One of the typical organic solar cells is a wet dye-sensitized organic solar cell that uses a liquid, and the other is an organic solar cell that uses a solid organic thin film such as a polymer formed by coating or the like (hereinafter referred to as the “organic solar cell”). It is called “organic thin-film solar cell”. The organic thin film solar cell includes a thin film layer (referred to as “photoelectric conversion layer”) for converting light energy into electric energy. As this photoelectric conversion layer, a structure in which a p-type semiconductor material (donor or electron donor) made of an organic material and an n-type semiconductor material (acceptor or electron acceptor) are separated is employed. One example is a structure called a bulk heterojunction (BHJ) layer in which a plurality of components are separated by phase separation in a bulk region having a certain thickness.

  In the mechanism of power generation in an organic thin film solar cell such as this BHJ layer, excitons (excitons) excited by the energy of incident photons (photons) play a major role. The excitons excited in the photoelectric conversion layer diffuse inside the photoelectric conversion layer, which is an organic thin film, and eventually reach the pn junction interface formed in the photoelectric conversion layer. Then, excitons are separated into free electrons and holes. The junction region in the vicinity of the pn junction interface involved in this separation (charge separation) is limited to a region close to the pn junction interface to the extent that diffusing excitons are not trapped. That region is also called the active layer. If the ratio of the active layer to the photoelectric conversion layer is small, the formed excitons are also deactivated and a sufficient photocurrent is not generated.

  In addition, excitons are generated when photons are incident, and even if free electrons and holes (generally referred to as “carriers”) are generated for charge separation from the excitons, carriers are not transmitted to the electrodes. It cannot be extracted as a photocurrent. In other words, in order to take out carriers as photocurrent, free electrons transferred to the n-type electron acceptor reach the electrode through the electron acceptor region, and holes are transferred to the n-type electron acceptor. Passing through the region of the p-type electron donor that has generated holes therein, the other electrode must be reached. Conversely, if the shape of the electron donor and electron acceptor is not capable of securing a route to such an electrode, even if charge separation is realized from the generated excitons, It cannot be taken out as generated power. For example, when the ratio of regions where the respective materials are dispersed independently and the path to the electrode without passing through the junction region is not sufficiently secured increases, the pn junction interface is reached and the charge separation of excitons is reached. Even if this occurs, the proportion of free electrons and holes that cause photocurrent decreases.

  The structure of the BHJ layer has certain advantages for the mechanism of power generation and power extraction inside the organic film in the general organic thin film solar cell described above. The advantage is that in the electron donor and the electron acceptor, if the pn junction interface in the photoelectric conversion layer, that is, the ratio of the active layer increases, and the domain size and dispersion / aggregation of the organic material can be controlled. It is possible to secure a route to reach the electrode. In the BHJ layer, more ideal structures are being sought. Specifically, one ideal structure in the BHJ layer is that the domain size is 10 nm or less and they are in contact with each other to form a percolation structure. Thus, the suitable photoelectric conversion layer preferable from the viewpoint of the mechanism inside the organic film in the organic thin film solar cell has many pn junction interfaces, and controls the domain size and dispersion / aggregation of the organic material up to the electrode. It can be said that it is a structure that secures a route to reach.

  For this reason, photoelectric conversion layers that can overcome the above-mentioned problems are the subject of intensive research and development. For example, in the technique disclosed in Patent Document 1 (Japanese Patent Application No. 2010-98034), a structure in which a BHJ layer is sandwiched between an organic hole transport layer and an organic electron transport layer is employed. In this case, a technique is adopted in which a polymerizable group is introduced into at least one organic layer and insolubilization treatment is performed so that each layer does not dissolve other layers (Patent Document 1, Claim 1, Paragraph [0022]). Etc.) As a result, according to the disclosure of Patent Document 1, a photoelectric conversion layer having both high photoelectric conversion efficiency and high durability is produced. Here, in a typical polymer type organic thin film solar cell, a p-type material is a conductive polymer, for example, poly (3-hexylthiophene) (hereinafter referred to as “P3HT”), and an n-type material is PCBM or the like. Fullerene derivatives are often used. Material development for polymer-type organic thin-film solar cells, including those other than these, is underway.

  In Non-Patent Document 1 (H. Hiramoto, et al., Appl. Phys. Lett. 88, 213105 (2006)), in the structure of a low-molecular organic solar cell, p-type (donor) is phthalocyanine, n-type ( Fullerene C60 is used for the acceptor. And the structure called an upright superlattice structure (Organic Vertical Super Lattice: OVSLs) is produced using the microtome. As a result, a nanostructure having a size of about 2 nm and an increased active layer is realized.

Japanese Patent Application No. 2010-98034

H. Hiramoto, et al., “Design of nanostructures for photoelectric conversion usingan organic vertical superlattice,” Appl. Phys. Lett. 88, 213105 (2006)

  However, it is very difficult to stabilize the BHJ layer forming process described above. There are many technical problems just by producing organic materials exhibiting electrically preferable n-type and p-type conduction characteristics, and further, phase separation of such a combination of materials into a desired structure is performed. This is necessary.

  Moreover, in patent document 1, in order to prevent melt | dissolution with a bulk heterojunction layer, the insolubilization process which irradiates an ultraviolet light with respect to a positive hole transport layer and is superposed | disclosed is disclosed. However, such polymerization is likely to increase the electrical resistance at the interface, and may deteriorate the electrical characteristics. Patent Document 1 does not mention the domain size or active layer of the bulk heterojunction layer that plays a central role in the mechanism for improving the performance of the photoelectric conversion layer, and discloses knowledge about efficient charge separation and transfer. Not done.

  Furthermore, Non-Patent Document 1 reports that a low molecular pn junction interface controlled to a micro level of several nanometers is formed. However, since the vapor deposition method is adopted for forming each layer, it takes much time to form the layer. In addition, in the upright superlattice structure disclosed in Non-Patent Document 1, electrodes are vapor-deposited on both sides and the electrical characteristics are measured. At the interface between such an electrode and the upright superlattice structure, sufficient adhesion between the upright superlattice structure, which is an organic material, and the metal cannot be obtained, and it is difficult to produce a highly practical organic thin film solar cell. .

  An object of the present invention is to solve at least some of the problems described above. The present invention contributes to the production of an organic thin-film solar cell having a highly efficient photoelectric conversion layer by adopting a production method that takes advantage of the polymer.

  As described above, in order to efficiently convert light energy into electric energy, it is preferable to control the ratio of the active layer of the photoelectric conversion layer. In addition, it is important to secure a carrier path from the active layer to the electrode. That is, if the exciton generated by the photon is deactivated, or the carrier travels from the pn junction interface to the electrode after the charge is separated from the exciton, the thin film having good characteristics is obtained. It is not possible to make a solar cell.

  In order to form an active layer structure that satisfies these requirements, a through structure is employed in the present invention. By adopting such a through structure, an element with high photoelectric conversion efficiency can be obtained. Moreover, in each aspect of the present invention, from the viewpoint of practicality, a contact layer is employed as a layer that does not hinder electrical operation while enhancing the adhesion between the electrode layer and the photoelectric conversion layer.

  That is, in an aspect of the present invention, the first and second electrode layers that form a pair of electrodes facing each other and at least one of which is translucent, and the first and second electrode layers face each other. A first conductivity type contact layer formed on one of the two surfaces, and a photoelectric conversion layer disposed in contact with the first conductivity type contact layer, the photoelectric conversion The layer includes a p-type organic polymer region and an n-type organic low-molecular region, and any direction in which the p-type organic polymer region and the n-type organic low-molecular region cross the thickness of the photoelectric conversion layer There is provided a thin-film solar cell having a through structure which is a structure extending in a vertical direction.

  The present invention can also be implemented as a method for producing an organic thin film solar cell. That is, in one aspect of the present invention, the step of forming the first electrode layer on a certain surface of the substrate and the first of either the p-type organic polymer contact layer or the n-type organic low-molecular contact layer. A step of forming a conductive contact layer and a step of forming a photoelectric conversion layer having a penetrating structure, wherein the penetrating structure includes a p-type organic polymer region and an n-type organic low-molecular region. A step of forming a photoelectric conversion layer and a step of forming a second electrode layer, the second electrode layer having the structure extending in any direction across the thickness of the first conductivity type Forming a second electrode layer which forms an electrode pair with the electrode layer, and either the first electrode layer or the second electrode layer exhibits translucency. 1 electrode layer, the first conductivity type contact layer, the photoelectric conversion layer And a manufacturing method of an organic thin-film solar cell wherein an organic thin film solar cell including the second electrode layer in this order from the side of the substrate is formed can be provided.

  When the contact layer is used, the adhesion between the electrode layer and the photoelectric conversion layer is enhanced and the electrical resistance is not adversely affected, so that a highly practical organic thin-film solar cell is provided.

  Throughout this application, the penetrating structure is a structure in which the p-type organic polymer region and the n-type organic low-molecular region extend in any direction across the thickness of the photoelectric conversion layer.

  In particular, in each aspect of the present invention, an alternate laminated film or laminate of p-type organic polymer layers and n-type organic low-molecular layers is used, and a strip member produced from the laminate is used. That is, in the present invention, the photoelectric conversion layer includes several strip members, and each strip member is a laminate in which p-type organic polymer layers and n-type organic low-molecular layers are alternately stacked. The p-type organic polymer layer and the n-type organic low-molecular layer are cut so as to have two cutting interfaces parallel to each other, and any one of the two cutting interfaces. Either one of the cutting interfaces is in contact with the first conductivity type contact layer, and the p-type organic polymer region and the n-type organic low-molecular region forming the penetrating structure are respectively formed on the strip member. The thin-film solar cell described above, which is formed by a p-type organic polymer layer and the n-type organic low-molecular layer, is provided.

  In the above aspect of the present invention, the second conductivity type contact layer which is different from the first conductivity type contact layer among the p-type organic polymer contact layer or the n-type organic low molecular contact layer. Forming the first electrode layer, the first conductivity type contact layer, the photoelectric conversion layer, the second conductivity type contact layer, and the second electrode layer. A method for manufacturing the above-described organic thin film solar cell is provided in which a thin film solar cell provided in this order from the substrate side is formed.

  The structure of the pn junction interface (active layer) of the photoelectric conversion layer of the present invention has many pn junction interfaces, and ensures a route to reach the electrode by controlling the domain size and dispersion / aggregation of the organic material. Is done. By using a strip member that is cut from the laminate, it is intentionally made into a structure with high photoelectric conversion efficiency.

  According to any aspect of the present invention, it is possible to produce an efficient and stable photoelectric conversion layer.

It is a perspective view which shows the main structures of the thin film solar cell provided in embodiment with this invention. It is a schematic sectional drawing which shows the cross section of the laminated body employ | adopted in the preparation methods of an example of the thin film solar cell of embodiment with this invention. It is a schematic perspective view which shows a mode that the strip member employ | adopted in the preparation method of an example of the thin film solar cell of embodiment with this invention is produced from a laminated body. FIG. 3A is a perspective view for explaining a strip member used for manufacturing a thin-film solar cell, and FIG. 3B is a perspective view for explaining a strip member that is cut at an angle from a laminated body. . It is a flowchart which shows the main procedures which manufacture the thin film solar cell in a certain embodiment of this invention. It is explanatory drawing which shows the variation of how to arrange a strip member in embodiment with this invention. In embodiment with this invention, it is explanatory drawing which shows the structure of the photoelectric converting layer by the strip member cut | disconnected by inclining. 6A shows a photoelectric conversion layer in which strip members cut at an angle are juxtaposed, and FIG. 6B shows a strip member cut at an angle in juxtaposition. The photoelectric conversion layer is shown.

  Hereinafter, embodiments of the present invention will be described. In the following description, unless otherwise specified, common parts or elements are denoted by common reference numerals throughout the drawings. In the drawings, each element of each embodiment is not necessarily shown in a scale ratio.

<First Embodiment>
[1 Overview]
Hereinafter, 1st Embodiment of this invention is described along an Example. In this embodiment, a through structure is formed in the production of the active layer of the photoelectric conversion layer. This penetrating structure has a p-type organic polymer region and an n-type organic low-molecular region. Hereinafter, the material that becomes the p-type organic polymer region is called a p-type material, and the material that becomes the n-type organic low-molecular region is called an n-type material.

[1-1 Through structure]
FIG. 1 is a perspective view showing a main configuration of a thin film solar cell 1000 provided in the present embodiment. In the thin film solar cell 1000 of this embodiment, the photoelectric conversion layer 100 and a layer called a contact layer are used. Specifically, in the thin film solar cell 1000, the anode 20 that is the first electrode and the cathode 10 that is the second electrode layer are arranged facing each other to form an electrode pair of the thin film solar cell 1000. . At least one of the cathode 10 and the anode 20 shows translucency. The thin-film solar cell 1000 includes a p-type organic polymer contact layer 22 (hereinafter referred to as a first conductivity type contact layer) on one of the two surfaces of the cathode 10 and the anode 20 facing each other. (Abbreviated as “p-type contact layer 22”). In addition, an n-type organic low-molecular contact layer 12 (“n-type contact layer 12”), which is a second conductivity type contact layer, is formed on the other surface. Note that a thin film solar cell having a structure in which the n-type contact layer 12 as the second conductivity type contact layer is not formed is also an embodiment of the present invention.

  The thin film solar cell 1000 includes a photoelectric conversion layer 100 disposed in contact with the p-type contact layer 22. This photoelectric conversion layer 100 has a p-type organic polymer region 102 and an n-type organic low-molecular region 104. The p-type organic polymer region 102 and the n-type organic low-molecular region 104 have a structure extending in any direction across the thickness D of the photoelectric conversion layer 100, that is, a penetrating structure.

  In the thin film solar cell 1000, at least a part of each p-type organic polymer region 102 is in contact with the p-type contact layer 22. When the n-type contact layer 12 is employed, at least a part of each n-type organic low molecular region 104 is in contact with the n-type contact layer 12. In the thin film solar cell 1000 shown in FIG. 1, the upper surface of the n-type organic low molecular region 104 on the drawing is in contact with the n-type contact layer 12, and the lower surfaces of the p-type organic polymer regions 102 are all p. It is in contact with the mold contact layer 22.

  In the thin film solar cell 1000 of the present embodiment, the photoelectric conversion layer 100 is formed while maintaining the state where the p-type and n-type materials are functionally separated as much as possible, and the penetrating structure is formed thereon. The In a specific example for producing the thin-film solar cell 1000, in order to form the p-type organic polymer region 102 and the n-type organic low-molecular region 104 of FIG. A stacked body 200 in which the respective materials are alternately stacked from the n-type materials is manufactured. FIG. 2 is a schematic cross-sectional view showing a cross section of the laminate 200 employed in the method for producing an example of the thin film solar cell 1000 of the present embodiment. In the present embodiment, the layer that finally becomes the p-type organic polymer region 102 is called a p-type organic polymer layer 202, and the layer that becomes the n-type organic low-molecular region 104 is called an n-type organic low-molecular layer 204. . As shown in FIG. 2, the stacked body 200 includes p-type organic polymer layers 202 and n-type organic low-molecular layers 204 that are alternately stacked. The number of laminations here is not particularly limited. The laminated body 200 in which the p-type organic polymer layer 202 and the n-type organic low-molecular layer 204 are alternately laminated has a p-type organic high-molecular layer as shown by chain lines in outlines of several layers above the paper surface of FIG. It is formed by an arbitrary process in which the molecular layer 202 and the n-type organic low molecular layer 204 are alternately stacked.

  In the exemplary manufacturing method in the present embodiment, the laminated body 200 is cut or cut so as to obtain cut surfaces parallel to each other, whereby the strip member 240 is formed. FIG. 3 is a schematic perspective view showing a state in which the strip member 240 employed in the manufacturing method of an example of the thin film solar cell 1000 of the present embodiment is manufactured from the laminate 200. Among these, FIG. 3A is a perspective view illustrating a strip member 240 used for manufacturing the thin-film solar cell 1000. FIG. 3B will be described later. The strip member 240 is formed by cutting the laminate 200 at the position indicated by the chain line in FIG. In the formed strip member 240, cut surfaces or cut interfaces 242 and 244 formed by cutting (hereinafter, the cut surfaces and the cut interfaces are collectively referred to as “cut surfaces”) are formed. These cut surfaces 242 and 244 are directed toward the anode 20 and the cathode 10, respectively, as shown in FIG. The strip member 240 is arranged with the cut surface facing the electrode in this way, and is used as the photoelectric conversion layer 100. As a result, the strip member 240 functions as the p-type organic polymer region 102 and the n-type organic low-molecular region 104 that are the p-type organic polymer layer 202 and the n-type organic low-molecular layer 204 in the laminate 200, and penetrates. A structure will be provided. In FIG. 1, two strip members 240 </ b> A and a strip member 240 </ b> B are clearly shown as the strip members 240, but these strip members 240 of the same kind are repeatedly arranged. There is no special restriction | limiting in the number of the strip members 240 contained in the photoelectric converting layer 100 in the thin film solar cell 1000 of this embodiment.

  As described above, in the thin-film solar cell 1000 in which the strip member 240 that is formed by cutting the stack 200 and used for the photoelectric conversion layer 100 is formed by functionally separating the p-type and n-type materials. The photoelectric conversion layer 100 is formed while maintaining the state. Therefore, the respective materials are not mixed with each other. In this respect, the thin-film solar cell 1000 of the present embodiment, once exemplified by a conventional BHJ layer, once mixed p-type and n-type materials, and then phase-separated to form a p-type organic polymer region and n This is greatly different from the method of forming a type organic low-molecular region.

[2 materials]
Next, the material employ | adopted for the thin film solar cell 1000 of this embodiment is demonstrated. In particular, materials for manufacturing the thin film solar cell 1000 will be described separately for materials for the photoelectric conversion layer 100 and materials for the n-type contact layer 12 or the p-type contact layer 22.

[2-1 Materials for photoelectric conversion layer]
In the photoelectric conversion layer 100, an amorphous polymer conductive material such as P3HT is employed as a typical p-type organic material. Furthermore, a fullerene derivative (PCBM) which is a low molecule is employed as a typical n-type organic material. In addition to these typical examples, various p-type polymer conductive materials and various n-type low-molecular conductive materials are used for the thin-film solar cell 1000.

  In order to produce the laminated body 200 for the thin film solar cell 1000 of the present embodiment, separate solutions are prepared by dissolving p-type and n-type organic materials in an organic solvent in a typical manufacturing method described later. Is done. For example, the organic solvent is preferably a good solvent that sufficiently dissolves both the p-type and n-type organic material components. And while employ | adopting such a solvent, solubility and the residual amount of a solvent are controlled. The solubility and the residual amount of the solvent are determined at the time of forming each layer of the p-type organic polymer layer 202 and the n-type organic low-molecular layer 204, and between the p-type organic polymer layer 202 and the n-type organic low-molecular layer 204. Is adjusted from the viewpoint of not dissolving the underlying layer at the time of alternately stacking layers. Specifically, the organic solvent to be employed and selection guidelines for its handling are the following two. One is that the solvent exhibits sufficient solubility for the p-type and n-type organic materials. The other is that when p-type organic material and n-type organic material are alternately laminated, the wet state cannot be continued for a long time so as not to be excessively mixed and uniformly dispersed. . In order to make these properties compatible, in the step of forming the laminate 200 from a solution dissolved in an organic solvent, a drying step is provided after coating, or a solvent having a low boiling point is employed. The idea is given. Note that the p-type and n-type organic semiconductor materials to be dissolved in the organic solvent may be either low molecules or polymers as long as the combination functions as a solar cell element.

[2-2 Materials for n-type contact layer 12 and p-type contact layer 22]
The material for the n-type contact layer 12 and the p-type contact layer 22 is typically selected from the same material as that for forming the n-type organic low molecular layer 204 and the p-type organic polymer layer 202. The

[3 Manufacturing method]
Next, the manufacturing method for manufacturing the thin film solar cell 1000 of this embodiment is demonstrated. FIG. 4 is a flowchart showing a main procedure for manufacturing the thin-film solar cell 1000. First, the anode 20 (FIG. 1) that is the first electrode is formed (S102). The anode 20 is typically formed on the surface of some substrate (not shown). Next, the p-type contact layer 22 which is a first conductivity type contact layer is formed (S104). The p-type contact layer 22 is also typically formed on the surface of the anode 20. Next, the photoelectric conversion layer 100 is formed (S110). This photoelectric conversion layer 100 is also typically formed on the surface of the p-type contact layer 22. When the second conductivity type contact layer is employed, an n-type contact layer 12 that is a second conductivity type contact layer is further formed (S120). Then, the cathode 10 as the second electrode is formed (S122). The surface on which the n-type contact layer 12 is formed is typically on the surface of the photoelectric conversion layer 100 or the surface of the cathode 10. Thus, an organic thin film solar comprising the anode 20 as the first electrode layer, the p-type contact layer 22 as the first conductivity type contact layer, the photoelectric conversion layer 100, and the cathode 10 as the second electrode layer in this order. A battery is formed. Further, when the n-type contact layer 12 is formed as the second conductivity type contact layer, the anode 20 as the first electrode layer, the p-type contact layer 22 as the first conductivity type contact layer, photoelectric conversion An organic thin-film solar cell including the layer 100, the n-type contact layer 12 as the second conductivity type contact layer, and the cathode 10 as the second electrode layer in this order is formed.

  In addition, the temporal order of each process of the manufacturing method of the thin film solar cell 1000 mentioned above is only an illustration, and the order of the process in this embodiment is not specifically limited to what was mentioned above. For example, the order in which the laminate 200 is formed in the photoelectric conversion layer forming step S110 to produce the strip member 240 and then the anode 20 is produced in the first electrode forming step S102 can be adopted. In addition, in order to form the strip member 240 formed in the photoelectric conversion layer forming step S110 on the surface of the n-type contact layer 12, the second electrode forming step is performed before or in parallel with the first electrode forming step S102. It is also possible to form the n-type contact layer 12 on the cathode 10 by carrying out S122 and then forming the second conductivity type contact layer (n-type contact layer 12) S120. When the process is employed, for example, the strip member 240 is juxtaposed on the surface of the n-type contact layer 12 on the surface of the cathode 10. In addition, about the formation process of each film | membrane, it is possible to employ | adopt various film-forming methods.

  In the photoelectric conversion layer forming step (S110), typically, as shown in FIG. 4, the step (S112) of forming the laminate 200 and the strip member 240 are formed by cutting the laminate 200. Step (S114). The formed strip member 240 is juxtaposed with the supportable member formed at that time (S116). An example of any such supportable member is on the surface of the p-type contact layer 22 of the substrate (not shown) on which the anode 20 and the p-type contact layer 22 are formed, and the cathode 10 and the n-type contact layer 12. On the surface of the n-type contact layer 12 of the substrate (not shown) on which is formed. This photoelectric conversion layer forming step (S110) will be further described in detail.

[3-1 Photoelectric Conversion Layer Formation Step (S110)]
[3-1-1 Laminate Forming Step (S112)]
In order to form the laminate 200, a printing method or a spray method is usually used on any substrate, film or object (not shown; hereinafter referred to as “temporary support for laminate”). This printing method includes flexographic printing, gravure printing, offset printing, and the like. In addition to these, a slit coater method, a spin coat method, a vapor deposition method, an electrostatic coating method, a powder coating method, and the like can also be employed.

  Various supports can be adopted as a temporary support for a laminate for forming the laminate 200. As an example of the temporary support for a laminated body suitable for the present embodiment, any flat substrate having a smooth surface can be adopted. It is also preferable to form a laminate using the outer surface of the cylinder as a temporary support for a laminate. Furthermore, it is also possible to form a laminate using the outer surface of the belt-shaped substrate forming a ring as a temporary support for the laminate. When the outer surface of the cylinder or the outer surface of the belt-like substrate is used as a temporary support for a laminate, the laminate 200 is formed by alternately laminating two kinds of materials. By rotating around the axis or rotating in the circumferential direction of the belt-like substrate, there is an advantage that a laminate having a relatively large number of layers can be easily formed.

[3-1-2 Formation of strip member (cutting, S114)]
In the strip member 240 obtained by cutting the laminated body 200, the cutting width W1 (FIG. 3A) of the laminated body 200 becomes the film thickness D (FIG. 1) of the photoelectric conversion layer 100. Therefore, the cutting width W1 is considered so as to be larger than a certain degree from the viewpoint of light utilization efficiency on the one hand and not to be unnecessarily large from the viewpoint of material utilization efficiency on the other hand. In addition, since the handling of the strip member 240 becomes difficult when the cutting width W1 is extremely small, the cutting width W1 is determined in consideration of this point. The cutting length L of the strip member 240 (FIG. 3A) is the length L (FIG. 1) in the extending direction of the strip member in the photoelectric conversion layer 100. When the cutting length L is set long as long as it can be handled, a thin film solar cell having a large area can be manufactured with a small number of steps. The number of strip members 240 employed in the thin film solar cell 1000 is not particularly limited. The strip member 240, which is a cut laminate, may be a single integrated member, or the area may be increased by connecting two or more strip members 240A and a strip member 240B in FIG. It is. Further, the shape of the strip member 240 is not particularly limited. It is preferable that the cut surface 242 and the cut surface 244 of the strip member 240 are formed as parallel as possible. This is because, in the thin film solar cell 1000 illustrated in FIG. 1, the thickness D <b> 1 of the photoelectric conversion layer 100 is determined at the cut surface 242 and the cut surface 244.

  In order to produce the strip member 240 by cutting from the laminated body 200, for example, an arbitrary cutting tool having a sharp blade edge, for example, a knife is used. In addition, the strip member 240 can be formed from the laminate 200 by using a cutting tool such as a precision cutter, slitter, or microtome. By these means, the cut surface 242 and the cut surface 244 are cut so as not to be as uneven as possible. For this reason, even though two cut surfaces (cutting interface, cutting plane) parallel to each other are defined throughout the present application, geometrical parallelism is not required for these cutting surfaces. Further, even if it is defined as a cutting plane, it does not mean that geometrically perfect flatness is required.

  In particular, in an example in which a laminated body is formed on the outer surface of a cylinder, for example, in a form having concentric layer boundaries such as annual rings and Baumkuchen seen in a cross section of a tree trunk, or of a stationery tape A laminated body is formed in a form that is wound and connected like a roll. For this reason, if a laminated body in which the outer surface of the cylinder is formed as a temporary support for a laminated body is adopted, it is not necessary to reciprocate a cutting means such as a knife for cutting, and a strip having a sufficiently long length L The member 240 can be manufactured. In that case, for example, a cutting member such as a knife is pressed against the laminated body 200 formed on the outer surface while rotating the cylindrical laminated temporary support body around the cylinder axis. If the cutting is continuously processed while the knife is fed and moved in the direction of the rotation axis, a sufficiently long strip member 240 is formed. By adding such a device for machining, it is possible to produce the strip member 240 as a member having a constant width W1. Similar effects can be achieved when the belt-like substrate is employed as a temporary support for a laminate.

[3-1-3 juxtaposition (S116)]
In FIG. 1, the strip member 240 </ b> A and the strip member 240 </ b> B are juxtaposed in the length L direction. The photoelectric conversion layer 100 of the thin film solar cell 1000 is not particularly limited to this. FIG. 5 is an explanatory view showing a variation in how the strip members 240 are arranged. For example, the strip members 240 are arranged side by side so that the strip members 240C and 240D shown in FIG. 5A are aligned in the direction of the width W2 perpendicular to the extending direction L of the strip members. The photoelectric conversion layer 100A can also be formed. The width W2 corresponds to the total thickness D2 in the stacked body 200 (FIG. 3).

  In the thin film solar cell 1000 shown in FIG. 1, the strip member 240 </ b> A and the strip member 240 </ b> B are separate strip members 240 that are cut from each other to form separate pieces. However, the shape of the strip member for forming the photoelectric conversion layer 100 is appropriately changed according to the shape of the strip member 240. In addition to the arrangement of strip members that are cut and arranged separately as shown in FIG. 1, for example, the strip member 240 having a length exceeding the extent of the cathode 10 or the anode 20 is the cathode 10 or the anode 20. In some cases, they are juxtaposed so as to meander in the plane while touching. For example, when the cathode 10 or the anode 20 is formed using a flexible substrate (not shown) and the flexible substrate is long, the strip member 240 is disposed so as to extend in the long direction. In addition, the strip members 240 may be arranged in the width direction perpendicular to the long direction. Furthermore, when the cathode 10 or the anode 20 is formed using a flexible substrate, the flexible substrate itself is made to be a cylindrical outer surface or a belt-shaped outer surface forming a ring, and the flexible substrate It is also effective to arrange the strip members 240 while rotating themselves around the axis of the cylinder or to circulate in the belt-like circumferential direction, and at the time of use, at least one piece is stretched while being cut.

  In addition, any member that has not been described so far, regardless of whether it remains in the final thin film solar cell or not, is adopted as part of the thin film solar cell 1000 of this embodiment and its manufacturing method. It is not excluded to do. In the present embodiment, necessary members and processes can be appropriately employed for practical necessity and other reasons. For example, in order to facilitate mechanical handling, the strip member 240 is placed on a temporary substrate, film, or object (hereinafter referred to as “strip member temporary support”) that does not remain in the thin film solar cell 1000. And a step in which the strip member 240 is peeled off from the strip member temporary support and transferred to a desired layer can be included as a part of this embodiment.

  Furthermore, in this embodiment, it is also possible to employ a photoelectric conversion layer 100B having strip members juxtaposed so that the photoelectric conversion layers 100 in the thin film solar cell 1000 are two or more layers. FIG. 5B is a perspective view showing the configuration of a photoelectric conversion layer 100B having two strip members. In particular, the photoelectric conversion layer 100B includes a first group of strip members 240D and 240E juxtaposed so as to extend in a certain direction, and a second group that intersects and extends in the extending direction of the first group of strip members 240D and 240E. Strip members 240F and 240G. In particular, in the photoelectric conversion layer 100B, the extending direction of the first group of strip members 240D and 240E is the x direction in the figure, while the extending direction of the second group of strip members 240F and 240G is the y direction and is orthogonal to each other. They are juxtaposed so as to extend in the direction. In the photoelectric conversion layer 100B, each of the first group of strip members 240D and 240E has the cut surface 244 of the two cut surfaces 242 and 244 as the n-type contact layer 12 (FIG. 1, not shown in FIG. 5). It is in contact. Each of the second group of strip members 240F and 240G has the cut surface 244 in contact with the other cut surface 242 of the first group of strip members 240.

  In this way, arranging the strip members of each layer in the intersecting direction using the two layers of strip members brings a great advantage in practice. When the extending directions cross each other, the p-type organic polymer region and the n-type organic low-molecular region are in contact with each other without special alignment. For this reason, even when the width W1 (FIG. 3) of the strip member is increased to make it difficult to increase the thickness D1 (FIG. 1), two or more strip members are arranged to obtain a substantial thickness D1. If adjustment to increase the thickness is performed, it is possible to prevent electrical inconvenience.

  In addition, the penetration structure of the photoelectric conversion layer employed in the thin film solar cell 1000 of the present embodiment is not necessarily limited to the p-type organic polymer region and the n-type organic low-molecular region extending in parallel with the thickness direction. No. When the strip member to be the photoelectric conversion layer is cut from the laminate 200, the strip member is cut in an inclined direction with respect to the thickness D2 (FIG. 3) of the laminate 200, and the p-type organic polymer layer 202 of the laminate 200 The direction in which the n-type organic low molecular layer 204 extends in the strip member is not parallel to the thickness direction of the photoelectric conversion layer. FIG. 6 is an explanatory diagram showing a configuration of a photoelectric conversion layer formed by strip members cut by being inclined. Among these, FIG. 6A shows a photoelectric conversion layer in which strip members that are inclined and cut are arranged in one layer, and FIG. 6B is a diagram in which strip members that are cut and inclined are arranged in two layers. The photoelectric conversion layer is shown. In the present embodiment, a strip member 250 that is inclined from the direction in which the stacked bodies are alternately stacked and cut across the layers can be used as the photoelectric conversion layer 100C. FIG. 3B is a perspective view illustrating a strip member 250 that is cut from the laminated body 200 at an inclination. As shown in FIG. 3B, also in the strip member 250A and the strip member 250B which are the strip members 250, the cut surface 252 and the cut surface 254 are typically cut so as to be parallel to each other. . In this case, the extending direction of the p-type organic polymer region and the n-type organic low-molecular region for the penetrating structure is not the direction that gives the shortest distance connecting the n-type contact layer 12 and the p-type contact layer 22. Even in that case, in the photoelectric conversion layer 100C, since the stacked body 200 in which the p-type organic polymer region and the n-type organic low-molecular region are separately formed as layers is used, the anode 20 and the cathode 10 are used. The conduction path of the carrier is reliably ensured. Thus, the direction when cutting the strip member from the laminate 200 does not necessarily need to be parallel to the direction of the thickness of the laminate 200. This is a great practical advantage in that the mechanical accuracy in the cutting process (S114) is not necessarily high.

  Furthermore, as shown in FIG. 6 (b), the strip members are stacked in two layers when cut obliquely, which is an aspect of the thin-film solar cell of this embodiment. Also in this case, as illustrated with reference to FIG. 5 (b), the extending directions of the strip members may be crossed with each other (not shown).

[4 Examples and Comparative Examples]
[4-1 Production of Examples]
Hereinafter, examples included in the above-described embodiment will be described. The materials, amounts used, ratios, processing contents, processing procedures, directions of elements or members, specific arrangements, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following specific examples.

[4-1-1 Production of Laminate]
P3HT (poly (3-hexylthiophene)) was used as a p-type organic semiconductor material having a penetrating structure in the photoelectric conversion layer 100, and PCBM (fullerene derivative: Phenyl C61-Butylic acid Methyl ester) was used as an n-type organic semiconductor material. . Specifically, 10.0 g of P3HT and 10.0 g of PCBM were prepared, and both P3HT and PCBM were stirred as solvents for 20 hours, thereby dissolving each in 500 mL of toluene to prepare separate solutions. And in order to form the laminated body 200, the board | substrate ("temporary support board | substrate for laminated bodies") was used as a temporary support body for laminated bodies. As the temporary support substrate for a laminated body, a polyimide substrate was adopted as a material that has heat resistance and chemical resistance, has little shrinkage, and can peel off the formed laminated body 200.

  As a coating method for forming the laminate 200 on the polyimide substrate, which is a temporary support substrate for a laminate, a P3HT solution was applied by spin coating, and a PCBM solution was spray-coated. Specifically, P3HT was applied by a spin coating method with a rotation condition of 2000 rpm × 120 seconds. This application was processed in a glove box filled with dry nitrogen. Then, the coated substrate was dried on a hot plate at a substrate temperature of 130 ° C. for 30 seconds to form a P3HT film as the p-type organic polymer layer 202. A PCBM solution was spray-coated on the surface of the P3HT film. A spray gun-type spray was adopted for spraying, and the carrier gas was nitrogen gas. The periphery of the P3HT film was also sufficiently within the spray range, and a spraying time of 1-2 seconds was employed. The PCBM solution was also dried on a hot plate at a substrate temperature of 130 ° C. for 30 seconds to obtain a PCBM film as the n-type organic low molecular layer 204. This was repeated and alternately laminated, and a laminate 200 was produced in which 1000 layers of P3HT films and PCBM films were laminated and P3HT films / PCBM films were alternately laminated. The thickness D2 shown in FIG. 3 was about 10 to 20 μm when 500 pairs (1000 layers) of P3HT film / PCBM film were laminated.

[4-1-2 Cutting of Laminate]
The laminate 200 in which P3HT films / PCBM films were alternately laminated was cut. A precision cutter with a microscope was used for cutting. Here, the cutting width W1 (FIG. 3) of the stacked body 200 becomes the film thickness D1 (FIG. 1) of the photoelectric conversion layer as it is. In the thin film solar cell produced as an example, the laminated body 200 that was cut was prepared by peeling the laminated body 200 from the polyimide substrate and cutting it to a width of 1 μm with a precision cutter with a microscope.

  Next, the anode 20 as the second electrode layer was formed. The material of the anode 20 is not particularly limited, and any material such as Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO) can be used. In order to operate as a solar cell, either the cathode 10 or the anode 20 is an electrode having translucency. In this example, a glass substrate whose surface was dry-cleaned by exposure to oxygen plasma was prepared, and an ITO film as an anode 20 was formed on the clean surface of the glass substrate by sputtering.

  A p-type contact layer 22 was formed on the surface of the anode 20 (ITO film) by applying one layer of P3HT film by spin coating. A strip member 240 prepared by cutting the laminate 200 on the surface of the P3HT film that was not dried was placed side by side with the cut surface 242 facing the P3HT film, and was naturally dried in that state. In this way, a photoelectric conversion layer in which the strip members 240 are arranged is formed, and only one layer of the strip members 240 is juxtaposed to form the photoelectric conversion layer 100. In this example, since the strip members 240 were arranged before the P3HT film on the anode 20 was dried, the interface between the photoelectric conversion layer 100 made of the strip members 240 and the p-type contact layer 22 was sufficiently adhered.

  Subsequently, a PCBM solution was applied on the cut surface 244 of the strip member 240 to be the photoelectric conversion layer 100 to form a PCBM film as the n-type contact layer 12. Then, the cathode 10 was formed on the surface of the n-type contact layer 12. The material of the cathode 10 is not particularly limited, and any metal film such as Al, Mg, and Ca can be used. In particular, other methods can be employed. In this example, the cathode 10 was formed by forming Al by a sputtering method and finally obtaining a thin film solar cell 1000 having an organic material as a photoelectric conversion layer.

[4-2 Production of Comparative Example]
P-type organic semiconductor material P3HT 20 mg and n-type organic semiconductor material PCBM 20 mg were simultaneously mixed in 1 mL of toluene, and further stirred for 20 hours to dissolve both p-type organic semiconductor material P3HT and n-type organic semiconductor material PCBM. Next, a glass substrate was prepared, and the surface was dry-cleaned with oxygen plasma. Thereafter, ITO was formed as an anode, and a P3HT / PCBM mixed solution was applied on the surface of the anode on the substrate by spin coating. The rotation condition was 2000 rpm × 120 seconds. The coating operation was performed in a glove box filled with dry nitrogen, and drying was naturally dried for 60 minutes in the glove box. Thus, a BHJ layer was obtained in which the P3HT region and the PCBM region were phase-separated from the P3HT / PCBM mixed solution. Thereafter, an aluminum anode was formed on the BHJ layer by sputtering to produce a comparative thin film solar cell.

[4-3 Comparison of Examples and Comparative Examples]
The energy conversion efficiency was measured about the Example and comparative example of the thin film solar cell element which were produced as mentioned above. Measurement conditions were such that the light receiving part was irradiated with light of an intensity of 100 mW / cm ^{2 from} a solar simulator (AM1.5G filter). The measurement items were short circuit current density (Jsc), open circuit voltage (Voc), and fill factor (FF). Furthermore, the energy conversion efficiency under the light irradiation conditions was calculated based on the following formula.
Energy conversion efficiency (%) = Jsc (mA / cm ² ) × Voc (V) × FF

なお、表１中の短絡電流密度の単位はｍＡ、開放電圧の単位はＶである。The evaluation results of the examples are shown in Table 1.

In Table 1, the unit of the short circuit current density is mA, and the unit of the open circuit voltage is V.

  From the above results, in the thin film solar cell 1000 of the present embodiment, when the comparative example of the structure of the BHJ layer is used as a reference, the short-circuit current density is 1.61 times, the fill factor is 1.93 times, and the open circuit voltage is 1. A significant performance improvement of 18 times was seen, and an efficiency improvement of 3.8 times was achieved. In addition, the thin-film solar cell 1000 of this embodiment can stably introduce a through structure into the photoelectric conversion layer 100. In addition, such a photoelectric conversion layer 100 can easily be adjusted in performance and can be manufactured in large quantities. That is, the photoelectric conversion layer 100 is obtained by changing the thickness of the photoelectric conversion layer 100 by changing the cutting width W1 (FIG. 3), or by juxtaposing the strip members 240 or changing the length L (FIG. 3) of the strip members 240. It is easy to change the light receiving area. In addition, since the area produced by the stacked body 200 can be easily expanded, there are few technical obstacles to easily increasing the number of strip members 240 juxtaposed.

  As described above, in the present embodiment, in a thin film solar cell having an organic material as a photoelectric conversion layer, it is possible to provide a thin film solar cell with stable performance, and consequently, the photoelectric conversion characteristics of the solar cell. Improvement is possible.

<First Embodiment: Modification>
The first embodiment described above is a specific embodiment for implementing the idea of the present invention, and various modifications are possible. For example, in the above-described first embodiment, the example in which the first electrode is the anode and the second electrode is the cathode has been described, but this combination can be reversed. Similarly, in the first embodiment described above, the first conductivity type contact layer has been described as a p-type organic polymer contact layer, and the second conductivity type contact layer has been described as an n-type organic low-molecular contact layer. The reverse is also possible. Even if these combinations are changed, it is possible to implement the idea of the present invention exemplified in the first embodiment.

  The embodiment of the present invention has been specifically described above. The above-described embodiments and examples are described for explaining the invention, and the scope of the invention of the present application should be determined based on the description of the scope of claims. Further, modifications that exist within the scope of the present invention including other combinations of the embodiments are also included in the scope of the claims.

  The present invention is used in equipment using solar cells.

1000 Thin-film solar cell 10 Cathode 20 Anode 100, 100A to 100C Photoelectric conversion layer 200 Laminate 202 P-type organic polymer layer 204 n-type organic low-molecular layer 240, 240A to 240G, 250, 250A to 250B Strip members 242, 244, 252 and 254 Cut surface (cut surface, cut interface)

Claims (14)

First and second electrode layers that form electrode pairs facing each other, at least one of which is translucent,
A contact layer of a first conductivity type formed on one of the two opposing surfaces of the first and second electrode layers;
A photoelectric conversion layer disposed in contact with the contact layer of the first conductivity type,
The photoelectric conversion layer includes a p-type organic polymer region and an n-type organic low-molecular region;
A thin film solar cell having a penetrating structure in which the p-type organic polymer region and the n-type organic low-molecular region extend in any direction across the thickness of the photoelectric conversion layer. Of the two surfaces of the first and second electrode layers facing each other, the second conductivity type formed on the surface on the side where the contact layer of the first conductivity type is not formed. A contact layer,
One of the first conductivity type contact layer and the second conductivity type contact layer is a p-type organic polymer contact layer in contact with at least a part of the p-type organic polymer region;
2. The n-type organic low molecular contact layer, wherein the other of the first conductive type contact layer and the second conductive type contact layer is in contact with at least a part of the n-type organic low molecular region. The thin film solar cell according to 1. The photoelectric conversion layer includes several strip members,
Each of the strip members cuts both the p-type organic polymer layer and the n-type organic low molecular layer from a laminate in which p-type organic polymer layers and n-type organic low-molecular layers are alternately laminated. It is cut so that it has two cutting interfaces parallel to each other in the direction,
One of the two cut interfaces is in contact with the first conductivity type contact layer,
The p-type organic polymer region and the n-type organic low-molecular region forming the penetrating structure are formed by the p-type organic polymer layer and the n-type organic low-molecular layer of the strip member, respectively. The thin film solar cell according to claim 1 or 2. The photoelectric conversion layer includes several strip members juxtaposed in one layer,
Each of the strip members contacts one of the two cut interfaces with a p-type organic polymer contact layer that is one of the first and second conductivity type contact layers, and cuts the other. By bringing the interface into contact with the n-type organic low-molecular contact layer which is the other of the first and second conductivity type contact layers, each of the strip members juxtaposed in one layer becomes the p-type organic polymer contact. The thin film solar cell according to claim 3, wherein a layer is connected to the n-type organic low-molecular contact layer. The laminate for the photoelectric conversion layer is a p-type organic polymer layer formed using at least one of a solvent coating method, a spray method, and a vapor deposition method, and at least a solvent coating method, a spray method, and a vapor deposition method. The thin film solar cell according to claim 3, wherein n-type organic low-molecular layers formed using any of them are alternately stacked. The several strip members are
A first group of strip members which are arranged extending in a certain direction and have one of the two cut interfaces contacting one of the first and second conductivity type contact layers;
The first group of strip members extends in an intersecting direction, and one of the two cutting interfaces of the first group of strip members is in contact with the other cutting interface. The thin film solar cell according to claim 3, comprising two groups of strip members. The thin film solar cell according to claim 3, wherein the some strip members are cut in a direction that inclines from a direction in which the stacked bodies are alternately stacked and crosses each layer. Forming a first electrode layer on a surface of the substrate;
forming a first conductivity type contact layer that is either a p-type organic polymer contact layer or an n-type organic low-molecular contact layer;
A step of forming a photoelectric conversion layer having a penetrating structure, wherein the penetrating structure is a structure in which a p-type organic polymer region and an n-type organic low-molecular region extend in any direction across the thickness of the photoelectric conversion layer. A step of forming a photoelectric conversion layer,
A step of forming a second electrode layer, wherein the second electrode layer forms an electrode pair with the electrode layer of the first conductivity type, and is formed of the first electrode layer or the second electrode layer. A step of forming a second electrode layer, any of which shows translucency,
Thereby, an organic thin film solar cell including the first electrode layer, the first conductivity type contact layer, the photoelectric conversion layer, and the second electrode layer in this order from the substrate side is formed. Organic thin film A method for manufacturing a solar cell. a step of forming a second conductivity type contact layer that is different from the first conductivity type contact layer among the p-type organic polymer contact layer or the n-type organic low molecular contact layer;
Thus, the thin film including the first electrode layer, the first conductivity type contact layer, the photoelectric conversion layer, the second conductivity type contact layer, and the second electrode layer in this order from the substrate side. The manufacturing method of the organic thin-film solar cell of Claim 8. A solar cell is formed. The step of forming the photoelectric conversion layer includes:
forming a laminate in which p-type organic polymer layers and n-type organic low-molecular layers are alternately laminated;
By cutting the laminate in a direction in which both the p-type organic polymer layer and the n-type organic low-molecular layer are cut, the p-type organic polymer layer and the n-type organic low-molecular layer The method for producing an organic thin-film solar cell according to claim 8, further comprising: forming a plurality of strip members each having two parallel cutting surfaces exposed on both sides. The step of forming the photoelectric conversion layer is to arrange the strip members side by side in one layer,
The cut surface of one of the two cut surfaces of each of the strip members is in contact with the first conductivity type contact layer, and the other cut surface is in contact with the second conductivity type contact layer. 10. The method for producing an organic thin film solar cell according to 10, The process of forming the said laminated body is a process of laminating | stacking the said p-type organic polymer layer and the said n-type organic low molecular layer alternately on the outer surface of a cylindrical body. Battery manufacturing method. Forming the laminate includes:
Forming a p-type organic polymer layer using at least one of a solvent coating method, a spray method, and a vapor deposition method;
The method for producing an organic thin-film solar cell according to claim 10, wherein the step of alternately forming the n-type organic low-molecular layer using at least one of a solvent coating method, a spray method, and a vapor deposition method is performed. The step of forming the photoelectric conversion layer includes:
Extending the first group of strip members in a certain direction and juxtaposing them in one layer; and
Placing the second group of strip members on the first group of strip members and juxtaposing them in a single layer in a direction intersecting the direction of extension of the first group of strip members,
Of the two cut surfaces in each of the first group of strip members, one cut surface is in contact with the first conductivity type contact layer, and the other cut surface is the two groups of the second group of strip members. The method for producing an organic thin-film solar cell according to claim 10, which is in contact with one of the cut surfaces.

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