JP2008141103A - Production method of photoelectric conversion device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a production method for obtaining a photoelectric conversion device arranged with an organic semiconductor layer having a high photoelectric conversion efficiency, capable of increasing the area of a p-n junction interface while preventing occurrence of an isolated semiconductor. <P>SOLUTION: The production method of a photoelectric conversion device comprises a step of laminating a first thermoplastic semiconductor resin comprising a first organic semiconductor layer (p-type or n-type) on a first electrode, a step of forming a first organic semiconductor layer having irregularity on the surface on the first electrode by heating and softening the laminated first thermoplastic semiconductor resin while pressing the same with a mold having minute irregularity, and releasing the same from the mold after cooling down, a step of forming a second organic semiconductor layer (n-type or p-type) on the first organic semiconductor layer formed with the irregularity, and a step of forming a second electrode on the second organic semiconductor layer. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a photoelectric conversion element having an interface (pn junction surface) between a p-type semiconductor layer and an n-type semiconductor layer.

The principle of a photoelectric conversion element or a solar cell is that excitons, which are pairs of electrons (−) and holes (+), are generated in a semiconductor layer by incident light. In the vicinity of the interface (pn junction surface) between the p-type semiconductor layer and the n-type semiconductor layer, electrons and holes are connected by diffusion (diffusion current), and a region with few electrons and holes (depletion layer) is formed. At the same time, a built-in electric field that attempts to draw electrons and holes back to the n-type and p-type regions, respectively, and a drift current that moves the electrons and holes are generated. In the thermal equilibrium state, the diffusion current and the drift current are balanced, and the Fermi level is constant.
Here, when energy larger than the forbidden band width of the semiconductor is given by incident light, electrons in the valence band absorb light in the pn junction region and are excited beyond the forbidden band to be conduction electrons (photoelectrons). As a result, holes remain in the trace (internal photoelectric effect). The generation of these photoelectrons increases the drift current and destroys the thermal equilibrium state. Due to the internal electric field formed in the depletion layer, photoelectrons move to the n-type semiconductor and holes move to the p-type semiconductor, and an electromotive force is generated.

As a photoelectric conversion element using an inorganic material, there are a single crystal silicon solar cell, an amorphous silicon solar cell, and the like. In addition, dye-sensitized solar cells, organic thin-film solar cells, and the like have been developed as photoelectric elements using organic materials.
Although solar cells currently on the market use inorganic materials, research and development of power generation systems using organic materials have been continuously conducted from the viewpoint of reducing environmental burden and reducing costs. Organic thin-film solar cells are expected to have a large area that can be manufactured at low cost by printing technology, light weight and flexibility.

There are multiple factors that affect the electromotive force (voltage) of the solar cell, but the most direct one is the area of the interface (pn junction surface) between the p-type semiconductor layer and the n-type semiconductor layer. This is because charge separation is performed only at the pn junction surface having a rectifying action, and high photoelectric conversion efficiency cannot be obtained unless the area of the pn junction surface is increased. Therefore, in the case of a pn junction by simple lamination (the junction surface is flat), the photoelectric conversion efficiency is the lowest.
In the case of an organic thin film solar cell, since the thickness of the pn junction region is smaller than that of a solar cell made of inorganic material silicon, an increase in the pn junction area is particularly important for achieving high efficiency.

  As a method for increasing the pn junction area of an organic thin film solar cell, there is a method employing a bulk heterojunction structure. A method for producing a bulk heterojunction structure by co-evaporation of low molecules and a method for mixing polymers have been proposed. In the case of a bulk heterojunction structure formed by co-evaporation of a low molecular semiconductor, a certain amount of layer separation occurs due to association / aggregation / crystallization of molecules, thereby expanding the junction area. On the other hand, in the case of a bulk heterojunction structure formed by mixing polymers, an electromotive force is improved by forming a conjugated network.

However, solar cells having a bulk heterojunction structure in part (p-i-n junction type) or all have a problem that an isolated semiconductor is formed in the bulk heterolayer.
When such an isolated semiconductor is formed in the bulk hetero layer, for example, in the case of an n-type semiconductor surrounded by a p-type semiconductor, it is isolated even if carriers are generated by incident light. The hole cannot move to the electrode. Since the isolated semiconductor has a large electric resistance for other carriers, the rectifying property is lowered.
For this reason, various bulk heterojunction structures that can increase the pn junction area while suppressing the generation of isolated semiconductors have been studied.

In Non-Patent Document 1, when the thickness of the bulk hetero layer of the p-i-n junction is continuously changed and the bulk hetero layer is about 10 nm, there is an optimal balance between the internal resistance and the photovoltaic voltage. It is described that it is obtained.
In Patent Document 1, a mixture of a p-type semiconductor such as a triphenylmethane derivative and an n-type semiconductor such as a porphyrin derivative is formed into a thin film between electrodes, and the mixture ratio is changed to change from p-type to n-type. A technique for increasing the carrier density and the photocurrent by controlling the valence electrons is introduced.
Patent Document 2 discloses that a good microphotoelectric separation structure is prepared by using an electron-donating block copolymer and an electron-accepting block copolymer for a p-type semiconductor and an n-type semiconductor, respectively. A technique for forming a conversion layer is introduced.
“Functional Materials”, November 2006, Vol. 26, No. 11, p60 Japanese Patent Laid-Open No. 09-074217 JP 2006-73900 A

However, it is considered difficult to suppress the generation of isolated semiconductors to zero with the above prior art method. Actually, in the mixed layer or the micro phase separation layer, local isolation of components is inevitable. Therefore, in order to improve the conversion efficiency, it is necessary to improve the structure of the pn interface.
The present invention has been made in view of the above circumstances, and can increase the area of the pn junction interface while preventing the generation of an isolated semiconductor, and an organic semiconductor layer having high photoelectric conversion efficiency is disposed. It is an object of the present invention to provide a production method for obtaining a photoelectric conversion element.

In order to achieve the above object, the present invention employs the following configuration.
[1] Photoelectric in which first and second organic semiconductor layers, one of which is made of p-type thermoplastic semiconductor resin and the other of which is made of n-type thermoplastic semiconductor resin, are arranged between the first and second electrodes. A method for manufacturing a conversion element, comprising: laminating a first thermoplastic semiconductor resin constituting a first organic semiconductor layer on a first electrode; and laminating the laminated first thermoplastic semiconductor resin. A step of forming a first organic semiconductor layer having irregularities on the surface on the first electrode by heating and softening while pressing with a mold having irregularities, and then cooling and peeling from the mold; And a step of forming a second organic semiconductor layer on the first organic semiconductor layer on which the irregularities are formed, and a step of forming a second electrode on the second organic semiconductor layer. A method for producing a photoelectric conversion element.

[2] Photoelectric in which first and second organic semiconductor layers, one of which is made of p-type thermoplastic semiconductor resin and the other of which is made of n-type thermoplastic semiconductor resin, are arranged between the first and second electrodes. A method for manufacturing a conversion element, the step of laminating a first thermoplastic semiconductor resin constituting the first organic semiconductor layer in a mold having fine irregularities, and the laminating first thermoplastic semiconductor resin, A step of forming a first organic semiconductor layer having irregularities on the surface on the first electrode by heating and softening while pressing with one electrode, cooling and peeling from the mold, and irregularities Comprising: a step of forming a second organic semiconductor layer on the first organic semiconductor layer on which is formed; and a step of forming a second electrode on the second organic semiconductor layer. A method for manufacturing a conversion element.

[3] In the step of forming the second organic semiconductor layer, the second thermoplastic semiconductor resin constituting the second organic semiconductor layer is applied onto the first organic semiconductor layer having the irregularities formed thereon. The manufacturing method of the photoelectric conversion element as described in [1] or [2] by the coating method.

  According to the manufacturing method of the present invention, it is possible to increase the area of the pn junction interface while preventing the generation of an isolated semiconductor, and to obtain a photoelectric conversion element in which an organic semiconductor layer having high photoelectric conversion efficiency is arranged. Can do.

[Configuration of photoelectric element]
The photoelectric conversion element manufactured according to the present invention includes a first organic material and a second organic material, one of which is made of p-type thermoplastic semiconductor resin and the other of which is made of n-type thermoplastic semiconductor resin, between the first and second electrodes. A photoelectric conversion element in which a semiconductor layer is arranged.

The first and second electrode materials are not particularly limited, and metals, alloys, metal compounds, inorganic semiconductors, conductive polymers, carbon, and the like can be used.
For example, metal thin films such as aluminum, gold, silver, copper, chromium, tungsten, and metal compounds such as ITO (Indium Tin Oxide), FTO (Fluorine doped Tin Oxide), AZO (Aluminium doped Zinc Oxide), tin dioxide, It is preferable because it has high conductivity and an appropriate work function.
The first and second electrodes may have a buffer layer on the organic semiconductor layer side.

The p-type thermoplastic semiconductor resin constituting one of the first and second organic semiconductor layers is a compound having thermoplasticity and an entire structure of π electron conjugated system, and having charge carriers as holes. It is.
Examples of the p-type thermoplastic semiconductor resin include, but are not limited to, poly (phenylene vinylene) derivatives, amine derivatives, metallocene derivatives, polythiophene derivatives, polypyrrole derivatives, copper phthalocyanine derivatives, and phthalocyanine derivatives.

The n-type thermoplastic semiconductor resin constituting the other of the first and second organic semiconductor layers is a compound that has thermoplasticity and has a π-electron conjugated system as a whole, and has charge carriers as electrons. Anything is acceptable.
Examples of the n-type thermoplastic semiconductor resin include, but are not limited to, fullerene derivatives, cyano group-containing poly (phenylene vinylene) derivatives, viologen derivatives, and perylene derivatives.

  Examples of combinations of p-type thermoplastic semiconductor resins and n-type thermoplastic semiconductor resins include poly (phenylene vinylene) derivatives and fullerene derivatives, poly (phenylene vinylene) derivatives, cyano group-containing poly (phenylene vinylene) derivatives, and amine derivatives. And viologen derivatives, metallocene derivatives and viologen derivatives, polythiophene derivatives and viologen derivatives, polypyrrole derivatives and viologen derivatives, poly (phenylene vinylene) derivatives and viologen derivatives, copper phthalocyanine derivatives and perylene derivatives, phthalocyanine derivatives and perylene derivatives, amine derivatives and perylene derivatives , Poly (phenylene vinylene) derivatives and perylene derivatives, polythiophene derivatives and perylene derivatives, polypyrrole derivatives and perylene derivatives, metallocene derivatives and perylene derivatives , Copper phthalocyanine derivatives and fullerene derivatives, amine derivatives and fullerene derivatives, polythiophene derivatives and fullerene derivatives, polypyrrole derivatives and fullerene derivatives, metallocene derivatives and fullerene derivatives, amine derivatives and cyano group-containing poly (phenylene vinylene) derivatives, copper phthalocyanine derivatives and cyano Group-containing poly (phenylene vinylene) derivatives, polythiophene derivatives and cyano group-containing poly (phenylene vinylene) derivatives, polypyrrole derivatives and cyano group-containing poly (phenylene vinylene) derivatives, metallocene derivatives and cyano group-containing poly (phenylene vinylene) derivatives, etc. However, it is not limited to these.

The photoelectric conversion element produced according to the present invention preferably has a support on the outside of one or both of the first and second electrodes from the viewpoints of production and use.
Any material may be used for the support as long as it has mechanical strength and can protect the first and second electrodes and the first and second organic semiconductor layers from the outside. For example, a metal substrate, a glass substrate, a plastic film, etc. are mentioned. In order to obtain a flexible photoelectric conversion element, it is preferable to use a plastic film. Moreover, when providing a support body on the outer side of both the first and second electrodes, it is necessary to use a transparent material on at least one side.

[Production Method 1]
The manufacturing method according to the first invention (manufacturing method 1) is a method employing a thermal imprint method. That is, a step of laminating the first thermoplastic semiconductor resin constituting the first organic semiconductor layer on the first electrode, and pressing the laminated first thermoplastic semiconductor resin with a mold having fine irregularities. However, after heating and softening, cooling and peeling from the mold to form a first organic semiconductor layer having irregularities on the surface on the first electrode, and the first irregularities formed A step of forming a second organic semiconductor layer on the organic semiconductor layer, and a step of forming a second electrode on the second organic semiconductor layer.

  The manufacturing method 1 includes a step of forming a first electrode on the first support before the step of laminating the first thermoplastic semiconductor resin, and the coating of the first thermoplastic semiconductor resin is performed by: It is preferable to carry out on the first electrode formed on the support. Moreover, it is preferable to provide the process of laminating | stacking a 2nd support body on a 2nd electrode after the process of forming a 2nd electrode.

The steps for forming the first electrode on the first support include a vapor deposition method such as a vacuum deposition method, a sputtering method, a CVD method, a PVD method, and an ion plating method, a sol-gel method, a spin coating method, etc. A coating method or the like can be adopted.
The film thickness of the first electrode is preferably 50 to 5000 nm. The surface resistance of the first electrode is preferably in the range of 0.5 to 700 Ω / sq. By setting the film thickness to 50 nm or more, the surface resistance can be set to 700 Ω / sq or less. Moreover, excessive cost can be avoided by setting the film thickness to 5000 nm or less.

In the step of laminating the first thermoplastic semiconductor resin on the first electrode, the first thermoplastic semiconductor resin diluted with a solvent is spin coated, doctor blade method, squeezing method, dip coating method, die coating method. The film can be laminated by a known method such as a coating method such as a bar coating method, a spray method or an air knife method, a printing method such as a screen printing method, an ink jet method, an offset printing method or a gravure printing method.
The solvent is not particularly limited as long as it is suitable for each lamination method and can dissolve the first thermoplastic semiconductor resin.
The thickness of the first thermoplastic semiconductor resin when laminated is preferably 10 to 10,000 nm. By setting the film thickness at the time of stacking to 10 nm or more, it becomes possible to provide sufficient unevenness in the subsequent step of forming the first organic semiconductor layer on the first electrode. Further, by setting the film thickness during coating to 10000 nm or less, the distance from the pn junction interface to the electrode can be shortened, and the resin material can be saved.

In the step of forming the first organic semiconductor layer on the first electrode, the coated first thermoplastic semiconductor resin is heated and softened while being pressed against the first electrode with a mold having fine irregularities. Then, it is cooled and peeled off from the mold, thereby forming a first organic semiconductor layer having irregularities on the surface on the first electrode.
The pressing may be either a surface pressure application by a stamp type or a linear pressure application by a roll type. In the case of applying a surface pressure, the surface pressure is preferably 0.1 to 100 MPa. In the case of applying linear pressure, the linear pressure is preferably 0.1 to 100 MPa.

  When the first thermoplastic semiconductor resin has a glass transition point, the heating temperature is preferably equal to or higher than the glass transition point. The cooling temperature is preferably less than the glass transition point. In order to facilitate peeling from the mold, the temperature after cooling may be lower than the temperature before heating.

  The mold is usually made of nickel or the like, but is not particularly limited thereto. Other various metals, inorganic substances, and organic substances can be used as long as they can withstand the use of thermal imprinting. It is preferable that the surface of the mold is appropriately treated with a release agent or the like.

The mold has a reverse (negative) structure of the concavo-convex structure transferred to the first thermoplastic semiconductor resin.
Considering increasing the area of the pn junction interface as much as possible, the pitch of the unevenness of the mold should be finer, and is preferably in the submicron order.
The deeper the unevenness, the better. However, it adjusts so that it may not become larger than the coating film thickness of 1st thermoplastic semiconductor resin. In addition, if the mold and the first thermoplastic semiconductor resin are poorly releasable, the uneven structure may be broken or stretched at the time of release, so the aspect ratio of the unevenness is 1 to 4. Between, preferably between 2 and 3.
Examples of the concavo-convex structure to be transferred include a structure in which the convex portion is a projection such as a cylinder or a cone, and a structure in which the concave portion is a U-shaped, U-shaped or V-shaped groove.

Any method may be used as a method for creating the mold. Preferably, a quartz or silicon substrate master is used. As a method for obtaining a master, for example, a method of processing a pattern on a quartz or silicon substrate by vapor phase etching with a gas such as CF ₄ , SF ₆ , Ar, or a silicon (100) substrate by liquid phase etching with KOH or the like. For example, a method of crystal anisotropic etching in the <211> direction can be used. When these methods are used, a master of a mold having fine irregularities with a pitch of 1 μm or less can be obtained. And the mold which has the same fine unevenness | corrugation as a master is obtained by electrocasting mold materials, such as nickel, to this master.

  Since the uneven pitch does not necessarily need to be 1 μm or less, the surface of the molding material is directly processed by, for example, several tens to several tens of μm by a sandblast method, or from several tens of μm by ultra-precision cutting. What gave the uneven | corrugated process of several hundred micrometers can also be used as a mold of this invention.

In the step of forming the second organic semiconductor layer on the first organic semiconductor layer having the unevenness, a coating method, a printing method, or a vapor deposition method can be adopted, but the concave portion of the first organic semiconductor layer is quickly filled. Therefore, it is preferable to employ a coating method in which the second thermoplastic semiconductor resin is coated on the first organic semiconductor layer.
This is because if the second thermoplastic semiconductor resin does not sufficiently enter the recesses of the first organic semiconductor layer, a pn junction cannot be formed and the pn junction interface cannot be enlarged.

As in the case of laminating the first thermoplastic semiconductor resin, the second thermoplastic semiconductor resin diluted with a solvent is used, spin coating method, doctor blade method, squeezing method, dip coating method, die coating method, bar coating method. And a coating method such as an ink jet method, a spray method and an air knife method, a screen printing method, an ink jet method, an offset printing method, a printing method such as a gravure printing method, and the like.
In particular, according to the spin coating method, it is possible to reach the fine portions of the concavo-convex structure relatively easily. Moreover, it can be effectively filled to the back of the concave portion by placing it under reduced pressure after coating. The solvent is not particularly limited as long as it is suitable for each forming method and can dissolve the second thermoplastic semiconductor resin.
The film thickness at the time of formation of the second thermoplastic semiconductor resin is preferably 10 to 10,000 nm based on the convex and concave surfaces of the first organic semiconductor layer. Conductivity in the second organic semiconductor layer can be obtained by setting the film thickness at the time of formation to 10 nm or more. Further, by setting the film thickness during coating to 10000 nm or less, the distance from the pn junction interface to the electrode can be shortened, and the resin material can be saved.

In the case of the vapor deposition method, the second thermoplastic semiconductor resin is vacuum deposited on the first organic semiconductor layer.
According to the vapor deposition method, the unevenness of the first organic semiconductor layer is easily reflected on the surface of the second organic semiconductor layer. Therefore, the surface of the photoelectric conversion element can be made uneven. In this case, the effect of preventing reflection of incident light can be exhibited.

In the step of forming the second electrode on the second organic semiconductor layer, the vacuum deposition method, the sputtering method, the CVD method, the PVD method are the same as the step of forming the first electrode on the first support. Further, a gas phase method such as an ion plating method, a coating method such as a sol-gel method, or a spin coating method can be employed.
The film thickness of the second electrode is preferably 50 to 5000 nm for the same reason as the film thickness of the first electrode. The surface resistance of the second electrode is preferably in the range of 0.5 to 700 Ω / sq for the same reason as the surface resistance of the first electrode.

In the step of laminating the second support on the second electrode, an adhesive is applied on the second electrode by a spin coating method, a doctor blade method, a bar coating method, or the like, and then the second support is attached to the second electrode. This is done by pasting together.
As the pressure-sensitive adhesive used here, any pressure-sensitive adhesive can be used regardless of whether it is water-based or solvent-based, as long as the second electrode and the second support are not damaged.

[Production Method 2]
The manufacturing method (manufacturing method 2) according to the second invention is a method employing a nano-casting method. That is, a step of laminating the first thermoplastic semiconductor resin constituting the first organic semiconductor layer on a mold having fine irregularities, and pressing the laminated first thermoplastic semiconductor resin with the first electrode Heating and softening, cooling and peeling from the mold to form a first organic semiconductor layer having irregularities on the surface on the first electrode, and the first irregularities formed Forming a second organic semiconductor layer on the organic semiconductor layer; and forming a second electrode on the second organic semiconductor layer.

The manufacturing method 2 includes a step of forming the first electrode on the first support body before the step of forming the first organic semiconductor layer on the first electrode, and the first thermoplastic semiconductor resin. The pressing is preferably performed by the first electrode formed on the support. Moreover, it is preferable to provide the process of laminating | stacking a 2nd support body on a 2nd electrode after the process of forming a 2nd electrode.
The method that can be employed in the process for forming the first electrode on the first support, and the film thickness and surface resistance of the first electrode formed thereby are the same as those described in Production Method 1.

In the process of applying the first thermoplastic semiconductor resin to the mold, the first thermoplastic semiconductor resin diluted with a solvent is used, spin coating method, doctor blade method, squeezing method, dip coating method, die coating method, bar coating It is laminated on the mold by a known method such as a coating method, an inkjet method, a spray method, a coating method such as an air knife method, a screen printing method, an inkjet method, an offset printing method, or a printing method such as a gravure printing method.
As the mold used in the production method 2, the same mold as that described in the production method 1 can be used.
The solvent is not particularly limited as long as it is suitable for each lamination method and can dissolve the first thermoplastic semiconductor resin.
The film thickness when the first thermoplastic semiconductor resin is laminated is preferably 10 to 10,000 nm based on the convex and concave surfaces of the mold. By setting the film thickness at the time of lamination to 10 nm or more, conduction in the first organic semiconductor layer can be obtained. Further, by setting the film thickness during coating to 10000 nm or less, the distance from the pn junction interface to the electrode can be shortened, and the resin material can be saved.

In the step of forming the first organic semiconductor layer on the first electrode, the first thermoplastic semiconductor resin applied to the mold was heated and softened while being pressed against the mold side by the first electrode. After that, by cooling and peeling from the mold, a first organic semiconductor layer having irregularities on the surface is formed on the first electrode.
The pressing may be either a surface pressure application by a stamp type or a linear pressure application by a roll type. In the case of applying a surface pressure, the surface pressure is preferably 0.1 to 100 MPa. In the case of applying linear pressure, the linear pressure is preferably 0.1 to 100 MPa.

  When the first thermoplastic semiconductor resin has a glass transition point, the heating temperature is preferably equal to or higher than the glass transition point. The cooling temperature is preferably less than the glass transition point. In order to facilitate peeling from the mold, the temperature after cooling may be lower than the temperature before heating.

In the step of forming the second organic semiconductor layer on the first organic semiconductor layer on which the unevenness is formed, the coating method, the printing method, and the vapor deposition method can be adopted as in the manufacturing method 1, but the same as the manufacturing method 1 It is preferable to employ a coating method for the reason.
As a coating method and a printing method, the same method as the manufacturing method 1 can be adopted. The solvent is not particularly limited as long as it is suitable for each forming method and can dissolve the second thermoplastic semiconductor resin.
The film thickness at the time of formation of the second thermoplastic semiconductor resin is preferably 10 to 10,000 nm on the basis of the convex and concave surfaces of the first organic semiconductor layer for the same reason as described in Production Method 1. .
The step of forming the second electrode on the second organic semiconductor layer and the step of laminating the second support on the second electrode can also be performed in the same manner as in manufacturing method 1.

[Example]
An electrode substrate in which an ITO transparent electrode having a thickness of 200 nm was laminated on a glass plate having a thickness of 0.5 mm, a length of 1 cm, and a width of 1 cm was subjected to alkali cleaning and ozone cleaning. After that, as an ITO buffer layer, polystyrene sulfonate (Bytron 4083, manufactured by Bayer) was spin-coated on the ITO transparent electrode with a thickness of 30 nm.
On top of this, a chloroform solution of poly-3-hexylthiophene (P3HT) as a p-type thermoplastic semiconductor resin was spin-coated at a thickness of 150 nm.
Next, a spin-coated p-type thermoplastic semiconductor resin layer is formed with a nickel mold having a fine structure pattern in which conical protrusions with a height of 120 nm are spread over the entire surface at a pitch of 80 nm, at a surface pressure of 5 MPa. Pressed. In this pressed state, the temperature of the nickel mold was raised to 80 ° C., maintained at 80 ° C. for 60 seconds, and then cooled to 25 ° C. After cooling, the nickel mold was peeled off to form a p-type first organic semiconductor layer in which a concave portion corresponding to the conical protrusion was formed on the entire surface.
Then, as an n-type thermoplastic semiconductor resin, a fullerene derivative [6,6] - phenyl _{-C 61} - tetrahydrofuran solution of butenoic acid methyl ester (PCBM), was spin-coated on the first organic semiconductor layer, The concave portion of the first organic semiconductor layer was filled, and the second organic semiconductor layer was formed on the convex surface by 30 nm.
Next, gold was deposited on the second organic semiconductor layer at a vacuum of 10 ⁻⁵ Torr to a thickness of 20 nm. Thereby, an organic thin film solar cell element having an effective area of 1 cm ² was prepared.
The organic thin-film solar cell element was irradiated with pseudo-sunlight (1 kW / m ² ) generated by a 500 W xenon lamp, and the photocurrent value at the time of short circuit was measured to be 4.2 μA.

[Comparative example]
An electrode substrate in which an ITO transparent electrode having a thickness of 200 nm was laminated on a glass plate having a thickness of 0.5 mm, a length of 1 cm, and a width of 1 cm was subjected to alkali cleaning and ozone cleaning. After that, as an ITO buffer layer, polystyrene sulfonate (Bytron 4083, manufactured by Bayer) was spin-coated on the ITO transparent electrode with a thickness of 30 nm.
On top of this, a chloroform solution of poly-3-hexylthiophene (P3HT) as a p-type thermoplastic semiconductor resin was spin-coated at a thickness of 150 nm to form a p-type first organic semiconductor layer.
Then, as an n-type thermoplastic semiconductor resin, a fullerene derivative [6,6] - phenyl _{-C 61} - tetrahydrofuran solution of butenoic acid methyl ester (PCBM), was spin-coated on the first organic semiconductor layer, A second organic semiconductor layer was formed by placing 75 nm on the surface of the first organic semiconductor layer.
Next, gold was deposited on the second organic semiconductor layer at a vacuum of 10 ⁻⁵ Torr to a thickness of 20 nm. Thereby, an organic thin film solar cell element having an effective area of 1 cm ² was prepared.
The organic thin-film solar cell element was irradiated with pseudo-sunlight (1 kW / m ² ) generated by a 500 W xenon lamp, and the photocurrent value at the time of short circuit was measured.

The organic thin-film solar cell element of the example had a higher photocurrent value than that of the comparative example, and was confirmed to be a good photoelectric conversion element.
This is presumably because the pn junction interface area of the device of the example is greatly expanded by the nanoimprint method. Moreover, according to the nanoimprint method, an isolated semiconductor such as a bulk hetero solar cell is not generated, so that the internal resistance is not increased.

Claims (3)

A photoelectric conversion element in which first and second organic semiconductor layers, one of which is made of p-type thermoplastic semiconductor resin and the other of which is made of n-type thermoplastic semiconductor resin, are arranged between the first and second electrodes. A manufacturing method comprising:
Laminating a first thermoplastic semiconductor resin constituting the first organic semiconductor layer on the first electrode;
The laminated first thermoplastic semiconductor resin is heated and softened while being pressed with a mold having fine irregularities, and then cooled and peeled from the mold, whereby the first organic semiconductor layer having irregularities on the surface Forming on the first electrode;
Forming a second organic semiconductor layer on the first organic semiconductor layer on which the irregularities are formed;
And a step of forming a second electrode on the second organic semiconductor layer. A photoelectric conversion element in which first and second organic semiconductor layers, one of which is made of p-type thermoplastic semiconductor resin and the other of which is made of n-type thermoplastic semiconductor resin, are arranged between the first and second electrodes. A manufacturing method comprising:
Laminating a first thermoplastic semiconductor resin constituting the first organic semiconductor layer on a mold having fine irregularities;
The laminated first thermoplastic semiconductor resin is heated and softened while being pressed by the first electrode, and then cooled and peeled from the mold, whereby the first organic semiconductor layer having irregularities on the surface is formed. Forming on the first electrode;
Forming a second organic semiconductor layer on the first organic semiconductor layer on which the irregularities are formed;
And a step of forming a second electrode on the second organic semiconductor layer. The step of forming the second organic semiconductor layer is based on a coating method in which a second thermoplastic semiconductor resin that constitutes the second organic semiconductor layer is applied onto the first organic semiconductor layer on which the irregularities are formed. The manufacturing method of the photoelectric conversion element of Claim 1 or 2.