JP2014056892A - Photovoltaic device, and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance photoelectric conversion efficiency of a photovoltaic device.SOLUTION: A photovoltaic device 1000 includes a photoelectric conversion layer 10, an electrode pair 20, and a plurality of metal structures 30. The photoelectric conversion layer is formed to be a certain thickness D, and composed of an organic semiconductor. The electrode pair faces each other by sandwiching the photoelectric conversion layer in a thickness direction. In the plurality of metal structures 30, surface plasmon resonance is induced by light hν incident on the photoelectric conversion layer 10. The light is incident on the photoelectric conversion layer 10 through a translucent substrate 80 and a translucent electrode 22, for instance. At least part of at least one of the plurality of metal structures 30 of the photovoltaic device 1000 is positioned in a range of a thickness of the photoelectric conversion layer 10. The metal structures 30 are electrically connected to one of the electrodes of the electrode pair 20. In one embodiment of the present invention, a photoelectric conversion element is provided in which an interface between the metal structure 50 and the photoelectric conversion layer 10 is inclined.

Description

  The present invention relates to a photovoltaic device and a manufacturing method thereof. More particularly, the present invention relates to a photovoltaic device using surface plasmon resonance and a method for manufacturing the photovoltaic device.

  Conventionally, photovoltaic elements such as solar cells and optical sensors have been manufactured using semiconductors such as crystalline silicon and amorphous silicon. In particular, compound semiconductors are also used in solar cells. In addition to those using these inorganic semiconductor materials, photovoltaic devices using organic materials exhibiting semiconductor characteristics (“organic semiconductors”) have also been developed. Organic semiconductors are attracting attention because they can be expected to have high productivity over a large area, and they can manufacture flexible solar cells and the like.

  In photovoltaic devices such as solar cells using organic semiconductors, excitons generated by incident light are separated into carriers of electrons and holes at the interface of the pn junction, and each carry is n After propagating through the p-type and p-type semiconductor parts, it is taken out as power. However, this exciton is deactivated while conducting a relatively short distance. As a countermeasure, reduce the distance traveled to the junction where the carrier separates, such as reducing the distance between the pair of electrodes sandwiching the organic semiconductor by thinning the organic semiconductor layer using the diffusion length, which is the average distance until deactivation, as a guide. Is done. On the other hand, when the organic semiconductor layer is thinned, there is a problem that light absorption of the organic semiconductor layer is weakened and light utilization efficiency is lowered. Thus, there is a trade-off regarding the thickness of the organic semiconductor layer between the carrier extraction efficiency and the light utilization efficiency. In order to solve this problem, a junction structure in which an interface where a junction is formed, such as a structure called a bulk heterojunction, is complicated even inside the bulk has been proposed. However, even when a bulk heterojunction is realized, the above trade-off problem regarding the layer thickness of the organic semiconductor layer has not been solved.

  On the other hand, the inventor of the present application uses various phenomena that utilize surface plasmon resonance in the wavelength range of light including infrared and visible, that is, electromagnetic field vibration that is resonantly excited on the metal surface in the frequency range of light. Is paying attention to. For example, Non-Patent Document 1 reports that a minute double cylindrical wall (DNP) of a metal is produced and surface plasmon resonance can be induced by light and its characteristics are reported.

  The control of light absorption using surface plasmon resonance is also disclosed in, for example, Patent Document 1 (Japanese Patent Laid-Open No. 2011-138950). Patent Document 1 discloses a configuration having a continuous or discontinuous cylindrical metal microstructure embedded in a photoelectric conversion layer and a dielectric film covering the inner and outer surfaces of the metal microstructure. Yes.

JP 2011-138950 A, for example, summary

Wakana Kubo, and Shigenori Fujikawa, “Au Double Nanopillars with Nanogap for Plasmonic Sensor,” Nano Lett. 11, 8-11 (2011)

  When a photovoltaic element using an organic semiconductor is used in, for example, a solar cell, there is a problem of the mismatch in the optimum thickness between the above-described efficiency of extracting carriers and the viewpoint of light utilization efficiency. Although this problem has been mitigated somewhat by improvements in organic semiconductor layers, there is still room for improvement. In other words, by adjusting the thickness of the organic semiconductor layer alone, there is only a compromise between the two purposes of increasing the efficiency of light extraction while increasing the efficiency of extracting carriers from the organic semiconductor. It is impossible to achieve both at a reasonable level.

  The present invention provides a photovoltaic device that increases the photoelectric conversion efficiency for converting light into electric power in a photoelectric conversion device that uses an organic semiconductor, and a method for manufacturing the photovoltaic device. It contributes to the conversion.

  The inventor of the present application has conceived of utilizing surface plasmon resonance in which free electrons resonate in response to light on the surface or interface of a metal structure and collectively move. And it confirmed that a particularly useful photovoltaic device could be produced, and came to create this invention.

  One of the modes is to operate the metal structure as an electrode. That is, in one aspect of the present invention, an organic semiconductor photoelectric conversion layer having a certain thickness is opposed to the photoelectric conversion layer sandwiched in the thickness direction, at least one of which is a translucent electrode, A plurality of metal structures that cause surface plasmon resonance to be induced by light incident on the photoelectric conversion layer, and at least one of the plurality of metal structures is at least partially in the photoelectric conversion layer. A photovoltaic device is provided that is located in the thickness range of the electrode pair and is electrically connected to any one of the electrodes of the electrode pair.

  In another aspect of the present invention, the structure of the metal structure reflecting the actual incident direction of light, specifically, the metal structure is inclined without necessarily operating the metal structure as an electrode. Thus, a high-performance photovoltaic device is provided. That is, in one aspect of the present invention, an organic semiconductor photoelectric conversion layer having a certain thickness is opposed to the photoelectric conversion layer sandwiched in the thickness direction, at least one of which is a translucent electrode, A plurality of metal structures that cause surface plasmon resonance to be induced by light incident on the photoelectric conversion layer, and at least a part of the plurality of metal structures is at least a part of the photoelectric conversion layer. The interface between the at least one of the plurality of metal structures and the photoelectric conversion layer is positioned in the thickness range of the photoelectric conversion layer toward at least a certain direction in the in-plane direction of the photoelectric conversion layer. There is provided a photovoltaic element having an inclined surface inclined from the direction of

  In this invention, the manufacturing method of a photoelectric conversion element is also provided. That is, in one aspect of the present invention, surface plasmon resonance is induced on a first electrode layer formed on a substrate by an organic semiconductor photoelectric conversion layer having a certain thickness and light incident on the photoelectric conversion layer. A plurality of metal structures to be disposed, a disposition step of disposing at least a part of the plurality of metal structures in the thickness range of the photoelectric conversion layer, and a combination with the first electrode layer And a step of forming a second electrode layer in contact with at least one of the plurality of metal structures and the photoelectric conversion layer so as to sandwich the photoelectric conversion layer in the thickness direction. A method for manufacturing a power device is provided. Further, at least one of a plurality of metal structures that cause surface plasmon resonance to be induced by incident light is brought into contact with the first electrode layer formed on the substrate to form the plurality of metal structures. Forming the photoelectric conversion layer of an organic semiconductor in contact with the plurality of metal structures and the first electrode layer to form a thickness from the first electrode layer; and A method of manufacturing a photovoltaic device including a step of forming a second electrode layer in contact with the photoelectric conversion layer so as to sandwich the photoelectric conversion layer in the thickness direction in combination with one electrode layer Provided.

  Furthermore, in one aspect of the present invention, the surface plasmon resonance is caused by a step of forming an organic semiconductor photoelectric conversion layer with a certain thickness on the first electrode layer formed on the substrate, and light incident on the photoelectric conversion layer. A step of positioning at least a part of the plurality of metal structures to be induced in the thickness range of the photoelectric conversion layer, and between the photoelectric conversion layer and at least one of the plurality of metal structures In the thickness direction in combination with the first electrode layer, and a step of causing the interface to have an inclined surface inclined from the thickness direction toward at least a certain direction in the in-plane direction of the photoelectric conversion layer; And a step of forming a second electrode layer in contact with the photoelectric conversion layer so as to sandwich the photoelectric conversion layer. Further, at least one of a plurality of metal structures that cause surface plasmon resonance to be induced by incident light is brought into contact with the first electrode layer formed on the substrate to form the plurality of metal structures. And an interface between at least one of the plurality of metal structures and the photoelectric conversion layer is inclined from the thickness direction toward at least a certain direction in an in-plane direction of the photoelectric conversion layer. Forming the photoelectric conversion layer of the organic semiconductor so as to have an inclined surface, and contacting the plurality of metal structures and the first electrode layer to form a thickness from the first electrode layer And a step of forming a second electrode layer in contact with the photoelectric conversion layer so as to sandwich the photoelectric conversion layer in the thickness direction in combination with the first electrode layer. Manufacturing method of power device It is also provided.

  In the present application, the light is not necessarily limited to visible light, but of any wavelength used for power generation or light detection in an organic semiconductor among electromagnetic waves included in wavelength regions such as ultraviolet light, visible light, and infrared light. Is included.

  In the present application, surface plasmon resonance typically refers to LSPR (Localized Surface Plasmon Resonances), which may also be referred to as local surface plasmon resonance or plasmon resonance. In a metal structure in which surface plasmon resonance is induced, an oscillating electric field having an enhanced amplitude due to collective motion of free electrons in the metal resonantly coupled with the electric field is generated in the vicinity thereof. This enhanced oscillating electric field becomes stronger as it approaches a metal structure disposed in the range of the photoelectric conversion layer, which is an organic semiconductor. This surface plasmon resonance is a phenomenon induced in a relatively wide frequency range (wavelength range) from ultraviolet to visible and infrared, although the frequency dependence (wavelength dependence) normally found in the resonance phenomenon is shown. It is not a phenomenon limited to a specific frequency or wavelength.

  Furthermore, the photovoltaic elements in the present application include any elements that extract electrical energy or signals using the intensity of light, including, for example, solar cells, photosensors, and imaging devices.

  In any embodiment of the present invention, a photoelectric conversion element that efficiently absorbs light and has improved efficiency is provided.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a partially cutaway perspective view showing a schematic structure of a photovoltaic device according to a first embodiment of the present invention. 2A and 2B are structural views showing the structure of the photovoltaic element according to the first embodiment of the present invention. FIG. 2A is a schematic sectional view in the in-plane direction, and FIG. 2B is a schematic sectional view in the thickness direction. FIG. 3 is a schematic cross-sectional view showing two typical structures of the photovoltaic element according to the first embodiment of the present invention, in which FIG. 3 (a) shows the photoelectric conversion element shown in FIGS. ) Is a schematic cross-sectional view of a photoelectric conversion element as another typical example. It is explanatory drawing which shows the structure of two photovoltaic devices which are another typical structures of 1st Embodiment of this invention. FIG. 4A is a perspective view illustrating a schematic structure of only one of the photovoltaic elements, and FIG. 4B and FIG. 4C are diagrams of one and the other photovoltaic elements. It is a schematic sectional drawing. In the typical example of the manufacturing process of the photoelectric conversion element of 1st Embodiment of this invention, it is a schematic sectional drawing which shows the structure in each step. It is a schematic sectional drawing which shows the structure in each step in another typical example of the manufacturing process of the photoelectric conversion element of 1st Embodiment of this invention. In the typical example of the manufacturing process of the photoelectric conversion element of 1st Embodiment of this invention, it is a schematic sectional drawing which shows the structure in each step. It is a schematic sectional drawing which shows the improved structural example of the photoelectric conversion element of 1st Embodiment of this invention. It is explanatory drawing which shows the structure of the photoelectric conversion element of 2nd Embodiment of this invention, Fig.9 (a) is a perspective view which fractures | ruptures and shows the schematic structure of a photovoltaic device partially, FIG. b) is a schematic sectional view. It is a perspective view which shows the structure of only a metal structure in some variations of the photoelectric conversion element of 2nd Embodiment of this invention. FIG. 10A shows the structure of the metal structure of the photovoltaic element shown in FIG. FIG. 10B shows a structure of a metal structure having only a single inclined plane. FIG. 10C shows a structure having metal structures of metal structures having different inclination directions. FIG. 10D shows a structure of a metal structure in which a plurality of minute inclined planes are combined. FIG. 10E shows a structure of a metal structure having only a part of the side surface of the truncated cone. In the photoelectric conversion element of 2nd Embodiment of this invention, it is sectional drawing which shows the structure of the photoelectric conversion element which has a metal structure electrically connected to any one electrode of an electrode pair. It is a scanning electron microscope (SEM) photograph which shows the arrangement | sequence of AuNPs on the temporary board | substrate in the Example of this invention. It is the schematic diagram explaining the monochrome optical photograph of the external appearance of the film surface of the sample of the Example of this invention, and the photograph. It is a SEM photograph of the film surface of the sample of the Example of this invention. It is the SEM photograph which fractured | ruptured another sample of the same stage as the production middle stage of the sample of the Example of this invention, and image | photographed the internal structure of the layer. It is the SEM photograph which fractured | ruptured another sample of the same step as the preparation middle step of the sample of the Example of this invention, and image | photographed the internal structure of the layer. An explanatory diagram in which the outline of AuNPs is added to the photographed SEM photograph is also appended. It is a graph of the extinction ratio spectrum which the arrangement | sequence of AuNPs arrange | positioned on the COP film which is another board | substrate utilized in order to produce the sample of the Example of this invention shows. It is a graph of the measured value of the absorption spectrum before and behind embedding AuNPs of the sample of the Example of this invention. It is the graph obtained about the current voltage characteristic of the sample piece with an Example of this invention about the part (curve D1) in which AuNPs are not arrange | positioned, and the part (curve D2) in which it is arrange | positioned. About each sample piece of the Example of this invention, photoelectric conversion efficiency (eta), the part (square mark) of the comparative example which does not provide AuNPs in the range of the thickness of a photoelectric converting layer, and the part of the Example which provided AuNPs (circle mark) ). It is a SEM photograph of the manufacture example of the metal structure for 2nd Embodiment of this invention. It is a SEM photograph of the manufacture example of the metal structure for 2nd Embodiment of this invention.

  Embodiments according to the present invention will be described below with reference to the drawings. In the description, unless otherwise specified, common parts or elements are denoted by common reference numerals throughout the drawings.

[1 First Embodiment]
[1-1 Basic structure / principle]
FIG. 1 is a perspective view showing a partially broken schematic structure of the photovoltaic device according to the first embodiment of the present invention. 2A and 2B are structural views showing the structure of the photovoltaic device according to the first embodiment of the present invention. FIG. 2A is a schematic sectional view in the in-plane direction, and FIG. 2B is a schematic sectional view in the thickness direction. FIG. 2A is a cross-sectional view at a position crossing the metal structure 30 in FIG. 1, and FIG. 2B is a cross-sectional view at the cutting position shown in FIG. FIG. 3 is a schematic cross-sectional view showing two typical structures of the photovoltaic element according to the first embodiment of the present invention, and FIG. 3A is the photovoltaic element shown in FIGS. FIG. 3B and FIG. 3B are schematic sectional views of a photovoltaic element 1100 as another typical example. Hereinafter, a schematic cross-sectional view without notice is a schematic cross-sectional view in the thickness direction, and is a cross-sectional view at a position crossing the metal structure. Moreover, in each figure of embodiment, the cross section and the hatching which shows a material are abbreviate | omitted except the metal part and another one part element.

  As shown in FIGS. 1 to 3, the photovoltaic element 1000 of the present embodiment includes a photoelectric conversion layer 10, an electrode pair 20, and a plurality of metal structures 30. The photoelectric conversion layer 10 is formed with a certain thickness D, and the material thereof is an organic semiconductor. The electrode pair 20 is opposed to the photoelectric conversion layer 10 in the thickness direction, and typically includes a translucent electrode 22 and a metal electrode 24. In the plurality of metal structures 30, surface plasmon resonance is induced by the light hν incident on the photoelectric conversion layer 10. For example, the light hν enters the photoelectric conversion layer 10 through the translucent substrate 80 and the translucent electrode 22.

  At least one of the plurality of metal structures 30 in the photovoltaic element 1000 is positioned in the range of the thickness D of the photoelectric conversion layer 10. The metal structure 30 is electrically connected to any electrode of the electrode pair 20. In the photovoltaic device 1000 illustrated in FIGS. 1, 2, and 3 (a), the metal structure 30 is electrically connected to the metal electrode 24 of the electrode pair 20. The photoelectric conversion layer 10 typically has a structure having a stacked structure in which a hole transport layer 12 and an active layer 14 are stacked. The active layer 14 includes an organic semiconductor of another component that functions as an n-type semiconductor and a p-type semiconductor.

  The inventors of the present application consider that the two effects of the optical action and the electrical action are synergistically useful for the reason that the photoelectric conversion efficiency is increased in the photovoltaic element 1000 having the above-described structure. The optical action is because surface plasmon resonance is induced in the metal structure 30 by light, and light absorption due to the coupling between the electric field enhanced by the surface plasmon resonance and the material of the photoelectric conversion layer 10 is substantially enhanced. is there. That is, disposing the metal structure 30 in the range of the thickness of the photoelectric conversion layer 10 means that it can correspond to increasing the thickness D of the photoelectric conversion layer 10 in terms of optical absorption. Yes. What is important is that the thickness D of the photoelectric conversion layer 10 does not have to be increased by using the metal structure 30 even for the purpose of obtaining this effect.

  As described above, surface plasmon resonance is induced by the light hν incident on the photoelectric conversion layer 10 in the plurality of metal structures 30. The electric field enhanced by the surface plasmon resonance serves to enhance the light absorption of the photoelectric conversion layer 10, particularly the active layer 14, so that the light that induces the surface plasmon resonance is large in the original material of the photoelectric conversion layer 10. Regardless of whether the wavelength indicates absorption or not, absorption of the photoelectric conversion layer 10 can be enhanced by the effect of the metal structure 30. However, more preferably, the plurality of metal structures 30 are configured so that surface plasmon resonance is induced by light in the light absorption wavelength range of the material of the photoelectric conversion layer 10. That is, the wavelength and resonance intensity at which surface plasmon resonance occurs in the plurality of metal structures 30 affect the metal material, shape, size, and mutual arrangement structure of the metal structures 30. Is done. For example, the peak wavelength or wavelength range of surface plasmon resonance can be specified by measuring the extinction ratio. Conversely, the wavelength at which surface plasmon resonance is induced can be adjusted by changing the configuration of the plurality of metal structures 30. For example, when the photovoltaic element 1000 is a solar cell that generates electric power, the original light absorption wavelength of the photoelectric conversion layer 10 (that is, in a state in which the plurality of metal structures 30 are not arranged) In comparison with the wavelength corresponding to the band gap of the material and the energy for generating excitons, the short wavelength light is absorbed and the long wavelength light is transmitted. For this reason, the photoelectric conversion layer 10 can efficiently convert light having a strong absorption wavelength into electric power. The wavelength range in which power can be efficiently converted can be estimated from the absorption spectrum in the combined state when a plurality of metal structures 30 are combined with the photoelectric conversion layer 10.

  Another electrical action can be described in more detail as a combination of the effect of increasing the area and the effect of shortening the distance. The area increasing effect is the effect of the photoelectric conversion layer 10 on the interface of the metal structure 30 connected to one of the electrode pairs 20 (the metal electrode 24 in the photovoltaic element 1000 of FIGS. 1 and 2). This is because all of the interfaces between the electrodes operate as electrode surfaces. Further, the distance shortening effect is an effect in which the distance from each position inside the photoelectric conversion layer 10 to the nearest electrode surface becomes closer due to the presence of the metal structure 30. That is, when viewed from each position where carriers are generated by the power generation operation, since the electrode can be reached with a shorter moving distance compared to the case where the metal structure 30 does not exist, the ratio of carriers that are deactivated decreases. Become. Note that it is not essential for realizing the present embodiment that both the effect of increasing the area and the effect of shortening the distance can be obtained. Both effects are common in terms of the role of the electrode as a collector for collecting carriers.

In a preferable configuration of the photovoltaic element 1000 with respect to these electric actions, a plurality of metal structures 30 that are electrically connected to any one of the electrode pairs 20 spread in the direction of the thickness D. It has an outer side 302 or an inner side 304 with components. At least one of the outer surface 302 and the inner surface 304 operates as an electrode for the photoelectric conversion layer 10. FIG. 3A schematically shows the flow of electrons e ^{− in} the operation as arrows indicating the flow of the metal electrode 24 and the metal structure 30. As shown in FIG. 3A, when the photovoltaic element 1000 is operated as a solar cell, the translucent electrode 22 becomes a cathode for supplying electrons when viewed from the internal photoelectric conversion layer 10, and the metal structure 30. The metal electrode 24 operates as an anode. This operation is performed when the photovoltaic element 1000 is viewed as a solar cell, with the translucent electrode 22 serving as a positive electrode and the metal electrode 24 connected to the metal structure 30 serving as a negative electrode.

  The synergistic effect of the optical action and the electric action described above is found in terms of increasing the efficiency of photoelectric conversion by the plurality of metal structures 30. In other words, the photovoltaic element 1000 is independent of each other as well as the optimum thickness setting of the photoelectric conversion layer 10 is not compromised, unlike the conventional photovoltaic element using an organic semiconductor. It is not limited to the compatible effects that each effect is exhibited. If this synergistic effect is described with an optical function as a starting point, it is assumed that the metal structure 30 is employed for the purpose of enhancing the substantial absorption of the photoelectric conversion layer 10 in the photovoltaic element 1000. In that case, even if it does not increase the actual value of the thickness D of the photoelectric converting layer 10, the optical effect | action of absorbing light more efficiently than before is acquired by employ | adopting the metal structure 30. FIG. Here, although the distance between the translucent electrode 22 and the metal electrode 24 remains the thickness D, the electrical performance in the photoelectric conversion layer 10 is the above-described area due to the addition of the metal structure 30. It is enhanced by an effect of at least one of an increase effect or a distance reduction effect, or a combination thereof. That is, only by adopting the metal structure 30, the photoelectric conversion efficiency can be enhanced from both the optical action and the electric action. Moreover, if the thickness D is set again on the assumption that the metal structure 30 is present, it can be expected that the photoelectric conversion efficiency is further increased. As described above, when the plurality of metal structures 30 included in the photovoltaic element 1000 are electrically connected to one of the electrodes and induce surface plasmon resonance by light, photoelectric conversion efficiency is obtained. Is greatly improved by the synergistic effect of electrical action and optical action.

[1-2 Structure example]
One preferred configuration of the present embodiment is the configuration of the photovoltaic element 1000 shown in FIGS. 1, 2, and 3A, that is, one of the electrode pairs 20 is a translucent electrode (the translucent electrode 22). ), And the other is a metal electrode (metal electrode 24). In this case, the connection destination of what is electrically connected to the electrode of the metal structure 30 is the metal electrode 24 as in the photovoltaic element 1000 in one typical example.

  Another typical example of this embodiment is a photovoltaic element 1100 shown in FIG. In the photovoltaic element 1100, a plurality of metal structures 32 are arranged in the thickness range of the photoelectric conversion layer 10 instead of the plurality of metal structures 30 in the photovoltaic element 1000 of FIG. Some of the metal structures 32 are electrically connected to the translucent electrode 22 of the electrode pair 20. The carrier flow in this case operates so that the metal structure 32 emits electrons. At this time, the outer surface 322 and the inner surface 324 of the metal structure 32 operate as electrodes that emit electrons. That is, when the photovoltaic element 1100 is operated as a solar cell, the translucent electrode 22 and the metal structure 32 serve as cathodes for supplying electrons and the metal electrode 24 serves as an anode when viewed from the inside photoelectric conversion layer 10. Works. In this operation, when the photovoltaic element 1100 is viewed as a solar cell, the translucent electrode 22 connected to the metal structure 32 serves as a positive electrode and the metal electrode 24 serves as a negative electrode.

  Also in the photovoltaic device 1100, preferably, the surface plasmon resonance is induced in the metal structure 32 in the range of the light absorption wavelength of the material of the photoelectric conversion layer 10.

  FIG. 4 is an explanatory diagram showing structures of the photovoltaic element 1200 and the photovoltaic element 1300 which are another typical configuration of the present embodiment, and FIG. 4A is an outline of the photovoltaic element 1200. FIG. 4B and FIG. 4C are schematic cross-sectional views of a photovoltaic element 1200 and a photovoltaic element 1300, respectively. The photovoltaic elements 1200 and 1300 also include the photoelectric conversion layer 10 and the electrode pair 20 described in the photovoltaic element 1000 and the photovoltaic element 1200, and elements constituting them.

  As shown in FIGS. 4A and 4B, the photovoltaic element 1200 includes a plurality of metal structures 34 in the photoelectric conversion layer 10. The metal structure 34 includes an inner cylindrical wall 34A and an outer cylindrical wall 34B that are arranged coaxially with each other. Both the inner cylindrical wall 34 </ b> A and the outer cylindrical wall 34 </ b> B of the metal structure 34 are electrically connected to the metal electrode 24. The metal structure 34 is made in a structure different from the metal structure 30 in the photovoltaic element 1000. By adjusting the material, shape and size of the metal structure 34, and the arrangement structure of the plurality of metal structures 34, the wavelength that gives the peak of surface plasmon resonance can be adjusted, and the surface plasmon resonance measured as the extinction ratio can be adjusted. It is possible to adjust the strength. In particular, the nanogap G serving as the gap between the inner cylindrical wall 34A and the outer cylindrical wall 34B has a metal structure in order to bring about an effect of enhancing the electromagnetic field of plasmon if the material and shape, particularly the thickness, are appropriately set. In the present embodiment employing 34, the absorption of the photoelectric conversion layer 10 can be increased. In addition, the position of the nanogap G is not formed in the photoelectric conversion layer 10, but is filled with a resin or the like whose thickness can be precisely controlled during the production as reported in Non-Patent Document 1, for example, It is also possible to dispose the same material as that of the photoelectric conversion layer 10. Arranging the photoelectric conversion layer 10 in the nanogap G that provides a stronger electric field enhancement effect is advantageous in that the efficiency of photoelectric conversion is improved. The metal structure 34 also operates as an electrode in the photoelectric conversion layer 10. By adjusting the material, shape and size of the metal structure 34 and the arrangement structure of the plurality of metal structures 34, plasma resonance by the metal structure 34 is induced for light in the absorption range of the photoelectric conversion layer 10. It is also possible to configure such that.

  The photovoltaic element 1300 includes a plurality of metal structures 36 in the photoelectric conversion layer 10. The metal structure 36 also includes an inner cylindrical wall 36A and an outer cylindrical wall 36B, which are individually arranged coaxially. Of the inner cylindrical wall 36 </ b> A and the outer cylindrical wall 36 </ b> B of the metal structure 36, the inner cylindrical wall 36 </ b> A is electrically connected to the translucent electrode 22. However, the outer cylindrical wall 36 </ b> B does not necessarily need to be electrically connected when the material for the nanogap G is disposed between the translucent electrode 22. The metal structure 36 is produced in a structure different from the metal structure 30 in the photovoltaic element 1000. Also in the metal structure 36, by adjusting the material, shape, size, and arrangement structure of the plurality of metal structures 36, the wavelength that gives the peak of surface plasmon resonance can be adjusted, or the extinction ratio It is possible to adjust the intensity of the surface plasmon resonance actually measured. The point that the metal structure 36 operates as an electrode in the photoelectric conversion layer 10, and the material, shape, size, and arrangement structure of the plurality of metal structures 36 are adjusted to cause plasma resonance by the metal structure 36. The point which can be configured to be induced with respect to light in the absorption range of the photoelectric conversion layer 10 is the same as in the case of the metal structure 34 of the photovoltaic element 1200.

[1-3 Manufacturing method]
Next, the manufacturing method of the photoelectric conversion element of this embodiment is demonstrated.

[1-3-1 Manufacturing Method of Photovoltaic Element 1000]
First, a typical manufacturing method of the photoelectric conversion element of this embodiment will be described by taking the photovoltaic element 1000 of this embodiment as an example. The manufacturing method for manufacturing the photovoltaic device 1000 generally includes an arranging step and a step of forming the metal electrode 24 (second electrode layer). The arranging step typically includes a step of forming the photoelectric conversion layer with a uniform thickness and a step of press-fitting a plurality of metal structures into the photoelectric conversion layer. Hereinafter, this typical manufacturing method will be described with reference to FIG.

[1-3-1-1 Press-fit using a separate substrate]
FIG. 5 is a schematic cross-sectional view showing the configuration at each stage in a typical example of the manufacturing process of the photoelectric conversion element of the present embodiment. In this typical example, the arrangement step is shown in FIGS. As shown in FIG. 5A, the photoelectric conversion layer 10 is formed on the translucent electrode 22 (first electrode layer) formed on the translucent substrate 80 with a uniform thickness. Next, as shown in FIG. 5B, the photoelectric conversion layer 10 is softened, and a plurality of metal structures 30 are pressed into the softened photoelectric conversion layer 10. In addition, the metal structure 30 is produced by arranging in advance on another substrate 90, and the manufacturing method thereof will be described later. Thereafter, when the separate substrate 90 is removed, the metal structure 30 is arranged in the range of the thickness of the photoelectric conversion layer 10 as shown in FIG. As described above, in the steps of FIGS. 5A to 5C, a plurality of organic semiconductor photoelectric conversion layers 10 having a certain thickness and a plurality of surface plasmon resonances induced by light incident on the photoelectric conversion layers 10. The metal structure 30 is disposed so that at least a part of the plurality of metal structures 30 is located within the thickness range of the photoelectric conversion layer 10. In the typical manufacturing method shown in FIG. 5, the upper surface of the metal structure 30 on the paper surface is exposed at the time of FIG.

  Then, as shown in FIG. 5D, a metal electrode 24 (second electrode layer) is formed. The metal electrode 24 sandwiches the photoelectric conversion layer 10 in the thickness direction in combination with the translucent electrode 22 (first electrode layer). The metal electrode 24 (second electrode layer) is formed in contact with at least one of the plurality of metal structures 30 and the photoelectric conversion layer 10.

  In order to form the metal structure 30 on the separate substrate 90, a part of the manufacturing method of the metal structure having a double cylindrical wall (DNP) described in Non-Patent Document 1 can be employed. Specifically, an array of solid cylindrical microstructures is first formed of a resist resin by using an imprint method with respect to another substrate 90. The entire resist surface including the arrangement thereof is covered with metal (for example, gold), and only the metal on the top of the cylinder and the substrate surface is removed by reactive ion etching or the like. At this point, metal remains only on the outer surface of the resist cylinder. Thereafter, the resist in the metal wall and the substrate surface is removed by etching (ashing) with oxygen plasma. With such a process, the metal structure 30 can be formed on the separate substrate 90.

  The method for manufacturing the above photovoltaic element 1000 can be variously modified within a range in which the photovoltaic element 1000 can be manufactured. For example, it is possible to produce a substantially similar structure without forming the metal structure 30 on the separate substrate 90. For example, the metal structure 30 is formed on the surface of the metal film of a substrate (not shown) on which the metal film to be the metal electrode 24 is formed, and the metal structure 30 is electrically connected directly to the surface of the metal electrode 24. Connect to. Then, if the metal structure 30 is press-fitted into the photoelectric conversion layer 10 by a process similar to the process described above, the photovoltaic element having a structure substantially similar to the photovoltaic element 1000 is simplified. It is possible to manufacture by the process.

[1-3-1-2 Direct Formation of Metal Structure 30]
The photovoltaic element 1000 can be manufactured without manufacturing the metal structure 30 on the separate substrate 90 according to a manufacturing method different from FIG. FIG. 6 is a schematic cross-sectional view showing a configuration at each stage in another typical example of the manufacturing process of the photoelectric conversion element of the present embodiment. In this typical example, the arrangement step is shown in FIGS. The manufacturing method shown in FIG. 6 is a method of generating the metal structure 30 directly on the layer of the photoelectric conversion layer 10 (active layer 14) by using a method such as an imprint method in the arranging step described above. That is, as shown in FIG. 6A, first, a precursor film 10A of the photoelectric conversion layer 10 is formed. This precursor film 10A is a laminate of a hole transport layer 12 and a precursor film 14A for the active layer 14. Next, as shown in FIG. 6B, the imprint mold 92 is pressed against the surface of the softened precursor film 10A to cure the precursor film 10A and then removed. Note that the imprint mold 92 can be manufactured, for example, by forming holes of an appropriate size in silicon by anisotropic etching. Thereby, the microstructure 14C is formed. At this time, the base portion 14B is left so as to cover the surface of the translucent electrode 22 with the material of the precursor film 10A. The microstructure 14C is, for example, a columnar protrusion from the base portion 14B. Next, as shown in FIG. 6C, a metal film to be a plurality of metal structures 30 is formed in contact with the surface of the microstructure 14C. Further, as shown in FIG. 6D, the gap between the plurality of metal structures 30 is filled with an organic semiconductor 14 </ b> D that becomes an active layer. The organic semiconductor 14D is connected to the base portion 14B and forms an integrated active layer 14 together with the microstructure 14C. The upper surface of the metal structure 30 on the paper surface is exposed. The placement process is completed at this stage. Thereafter, as shown in FIG. 6E, the metal electrode 24 is disposed.

  In the photovoltaic element 1000 manufactured as described above, both the microstructure 14C and the active layer 14 have a photoelectric conversion function.

[1-3-2 Manufacturing Method of Photovoltaic Element 1100]
Next, a method for manufacturing the photovoltaic element 1100 shown in FIG. FIG. 7 is a schematic cross-sectional view showing a configuration at each stage in a typical example of the process for producing the photoelectric conversion element of the present embodiment. The manufacturing method shown in FIG. 7 includes a step of forming a plurality of metal structures, a step of forming a photoelectric conversion layer of an organic semiconductor, and a step of forming a metal electrode 24 (second electrode layer).

  In the step of forming the plurality of metal structures, the translucent electrode 22 (in which at least one of the plurality of metal structures 32 in which surface plasmon resonance is induced by the incident light is formed on the substrate ( It is carried out by contacting the first electrode layer). Typically, as shown in FIG. 7A, the micro temporary structure 16 is formed on the translucent electrode 22. For example, a resin material suitable for imprinting can be molded as the micro temporary structure 16, and an imprint mold (not shown) can be used for the molding. At this time, unlike the case described with reference to FIG. 6, the base portion is not left and the surface of the translucent electrode 22 is exposed. After that, as shown in FIG. 7B, the metal film to be a plurality of metal structures 32 is brought into contact with the surface of the micro temporary structure 16 and connected to the translucent electrode 22 (first electrode layer). Form. After the metal film is formed over the entire surface including the surface of the translucent electrode 22 and the top of the micro temporary structure 16, the outer surface of the micro temporary structure 16 is formed by, for example, RIE (reactive ion etching) such as argon ion etching. Other parts can be removed leaving only. In this case, the plurality of metal structures 32 are in contact with the translucent electrode 22 (first electrode layer), and each of the metal structures 32 and the translucent electrode 22 are electrically connected. ing.

  Further, as shown in FIG. 7C, the micro temporary structure 16 is removed, and the interior of the metal structure 32 is made hollow. If the metal structure 32 is a metal that is not easily oxidized, such as gold, the imprinting resin of the micro temporary structure 16 is, for example, hydrogen by etching (ashing) using oxygen plasma or a metal that is easily oxidized. It can be selectively removed by etching with plasma.

  Next, as shown in FIG. 7D, a certain thickness is formed from the translucent electrode 22 while being in contact with the plurality of metal structures 32 and the translucent electrode 22 (first electrode layer). The organic semiconductor photoelectric conversion layer 10 is formed. In order to form the photoelectric conversion layer 10, for example, the hole transport layer 12 is formed, and then the active layer 14 is formed. Typically, the photoelectric conversion layer 10 is formed to a thickness such that the metal structure 32 is not exposed. Preferably, the hole transport layer 12 is formed on the entire exposed surface of the metal structure 32, that is, on the outer surface, the top, and the inner surface of the metal structure 32 (the portion from which the micro temporary structure 16 is removed). All are formed. When the active layer 14 is formed on the surface of the hole transport layer 12 thereafter, the operation as an electrode by the metal structure 32 becomes ideal, which is preferable. In order to form the translucent electrode 22 in this way, for example, a film forming method such as an electrostatic adsorption method can be employed. However, even if the hole transport layer 12 is formed only on the surface of the translucent electrode 22 and is not formed on the surface of the metal structure 32, the effect of this embodiment is sufficiently exhibited.

  Then, as shown in FIG. 7 (e), the photoelectric conversion layer 10, for example, the active layer is sandwiched between the translucent electrode 22 (first electrode layer) and sandwiched in the thickness direction. 14, the metal electrode 24 (second electrode layer) is formed, and the photovoltaic device 1100 is completed. In the photoelectric conversion operation of the photovoltaic element 1100, light incident from the lower surface on the paper surface through the transparent substrate 80 and the transparent electrode 22 is directly absorbed by the photoelectric conversion layer 10, and metal This is realized by being efficiently absorbed by the active layer 14 of the photoelectric conversion layer 10 by absorption through the photoelectric field enhanced by the structure 32.

[1-3-3 Manufacturing Method of Photovoltaic Element 1200]
Any of the manufacturing methods shown in FIGS. 5 and 6 described above can also be employed for manufacturing the photovoltaic device 1200 (FIG. 4B). For example, in order to manufacture the photovoltaic device 1200 by the manufacturing method illustrated in FIG. 5, it is necessary to form the metal structure 34 on the separate substrate 90. In this case, the metal structure 34 is manufactured by a method for manufacturing a metal structure having a double cylindrical wall reported by a part of the inventors of the present application in Non-Patent Document 1.

  Specifically, first, an array of solid cylinders made of resist resin is formed on another substrate 90 by an imprint method. The entire resist surface including the arrangement thereof is covered with metal (for example, gold), and the metal on the top of the cylinder and the substrate surface is removed by reactive ion etching or the like. At this point, metal remains only on the outer surface of the resist cylinder, which becomes the inner cylindrical wall 34A. Further, the whole is covered with a resin that becomes a spacer layer satisfying the nanogap G, and further a metal layer is covered. The spacer layer that becomes the nanogap G can be formed by controlling the thickness in units of molecular layers or atomic layers, and the space between the inner cylindrical wall 34A and the outer cylindrical wall 34B depends on the thickness of the nanogap G itself. The distance can be controlled. Thereafter, the metal and the spacer layer are removed only by the reactive ion etching or the like, and only the top of the cylinder and the substrate surface. At this point, the outer cylindrical wall 34B is also formed. Thereafter, the resist inside the remaining inner cylindrical wall 34A and the substrate surface is removed by etching (ashing) with oxygen plasma. With such a process, the metal structure 34 can be formed on the separate substrate 90. At this time, the spacer layer at the position of the nanogap G is also removed.

[1-3-4 Manufacturing Method of Photovoltaic Element 1300]
The manufacturing method of the photovoltaic device 1300 (FIG. 4C) also includes the photovoltaic device in that the metal structure 36 is formed on the translucent electrode 22 and then the hole transport layer 12 and the active layer 14 are formed. A technique according to the manufacturing method of the element 1100 can be employed. At this time, the method of forming the inner cylindrical wall 36A and the outer cylindrical wall 36B of the metal structure 36 through the nanogap G can be the same as the method described above with respect to the photovoltaic element 1200.

[1-4 Details of structure]
Various improvements that increase the practicality can be added to the photovoltaic elements 1000 to 1300 of the present embodiment. FIG. 8 is a schematic cross-sectional view illustrating an improved structure example of the photoelectric conversion element of the present embodiment. If the photovoltaic element 1000a which improved the photovoltaic element 1000 of this embodiment is demonstrated to an example, as shown to Fig.8 (a), it will electrically connect to the electrode of the some metal structure 30. FIG. It is useful to form an oxide film 40 made of the metal structure 30 on at least a part of the surface facing the translucent electrode 22. The surface on which the oxide film 40 is formed faces the surface facing the translucent electrode 22, that is, one electrode (metal electrode 24) of the electrode pair 20 to which the plurality of metal structures 30 are connected. This is the surface facing the other electrode (translucent electrode 22). The oxide film 40 usually has lower electrical conductivity than the metal structure 30 and exhibits, for example, insulation. For this reason, the formation of the oxide film 40 can effectively prevent an unexpected short circuit between the metal electrode 24 to which the metal structure 30 is connected and the translucent electrode 22. In the metal structure 30, the oxide film 40 can be formed, and examples of materials that can cause surface plasmon resonance include aluminum, silver, and copper.

  Similarly, in the photovoltaic element 1100a obtained by improving the photovoltaic element 1100, it is preferable to form the oxide film 42 on the metal structure 32 as shown in FIG. 8B. The surface on which the oxide film 42 is formed has the other electrode (the metal electrode 24) facing the one electrode (the translucent electrode 22) of the electrode pair 20 to which the plurality of metal structures 32 are connected. ).

[2 Second Embodiment]
[2-1 Basic structure / principle]
The present invention can also be implemented by a second embodiment which is an embodiment different from the first embodiment. FIG. 9 is an explanatory view showing the structure of the photoelectric conversion element according to the second embodiment of the present invention, and FIG. 9A is a perspective view showing the schematic structure of the photovoltaic element 2000 in a partially broken view. FIG. 9B is a schematic sectional view.

  The photovoltaic element 2000 generally includes the photoelectric conversion layer 10, the electrode pair 20, and a plurality of metal structures 50. The photoelectric conversion layer 10 is an organic semiconductor layer having a certain thickness D. The electrode pair 20 is opposed to the photoelectric conversion layer 10 in the direction of the thickness D, and at least one of them is a translucent electrode. In FIG. 9, the translucent electrode 22 on the translucent substrate 80 side is the translucent electrode, and the other is the metal electrode 24. In the metal structure 50, surface plasmon resonance is induced by the light hν incident on the photoelectric conversion layer 10. At least a part of the metal structure 50 is located in the range of the thickness D of the photoelectric conversion layer 10.

  As shown in FIG. 9, the interface between at least one of the metal structures 50 and the photoelectric conversion layer 10 is oriented in the direction of the thickness D of the photoelectric conversion layer 10 toward at least a certain direction in the in-plane direction of the photoelectric conversion layer 10. The outer surface 502 and the inner surface 504 are inclined surfaces inclined from the inner side. The metal structure 50 shown in FIG. 9 has a shape of a side surface converging toward the truncated conical metal electrode 24 whose axis is oriented in the direction of the thickness of the photoelectric conversion layer 10, and the outer side surface. 502 and the inner side surface 504 are both sides of the thickness of the metal layer of the metal structure 50. That is, the outer surface 502 and the inner surface 504 are examples of inclined surfaces that are inclined from the thickness direction of the photoelectric conversion layer 10 at each position. The inclined surface that can be taken by the interface between at least one of the metal structures 50 and the photoelectric conversion layer 10 in the present embodiment is a side surface of a pyramid, an inclined surface, an inclined curved surface, in addition to the side surface of the cone. Any inclined surface can be used. In addition, about the inclination, it is inclined from the direction of the thickness of the photoelectric conversion layer 10 toward at least a certain direction in the in-plane direction of the photoelectric conversion layer 10, because the metal structure of the present embodiment and the photoelectric conversion layer 10 are When each position of the interface between the two is viewed locally, the normal vector at the interface standing at that position has an in-plane component of the photoelectric conversion layer 10 in the direction, and the photoelectric conversion layer 10 This means that the component in the thickness direction is not zero.

  Preferably, in the plurality of metal structures 50, surface plasmon resonance is induced in the range of the light absorption wavelength of the material of the photoelectric conversion layer 10.

  It should be noted that, unlike the metal structures 30 to 36 in the photovoltaic elements 1000 to 1300 of the first embodiment, the metal structure 50 of the photovoltaic element 2000 is applied to any electrode of the electrode pair 20. It is a point including the structure which is not electrically connected. As clearly shown in FIG. 9B, the metal structure 50 is not in contact with any electrode of the electrode pair 20, and the material of the active layer 14 or the hole transport layer 12 is located between the electrodes. ing.

  Also in the photovoltaic device 2000, the efficiency of photoelectric conversion is increased as in the photovoltaic device 1000 of the first embodiment. Regarding the cause, the inventors of the present application consider that the optical action is strongly influenced. As in the case of the metal structure 30 in the first embodiment, the optical action is such that surface plasmon resonance is induced by light in the metal structure 50, thereby causing the electric field vibration enhanced by the surface plasmon resonance to be reflected in the photoelectric conversion layer. As a result of the interaction of the ten materials, the light absorption of the photoelectric conversion layer 10 is substantially enhanced. In particular, since the metal structure 50 is disposed within the thickness range of the photoelectric conversion layer 10 and the interface with the photoelectric conversion layer 10 is an inclined surface, the metal structure 50 is incident on the photovoltaic element 2000 and has a photoelectric property. Surface plasmon resonance is efficiently induced by the light propagating through the conversion layer 10. In general, surface plasmon resonance is efficiently induced when the interface between the photoelectric conversion layer 10 and the metal structure 50 is along the direction of the photoelectric field. Since light is a transverse wave, when the interface is inclined from the thickness direction of the photoelectric conversion layer 10 like the metal structure 50, surface plasmon resonance is efficiently induced when the light crosses the photoelectric conversion layer 10. The

  In particular, when the actual photovoltaic element 2000 is used as a solar cell, for example, and is intended to generate electric power from sunlight in a fixed installation, the solar diurnal movement or annual movement causes the sunlight. Does not necessarily enter only in the direction of the thickness direction of the photoelectric conversion layer 10. Even in that case, surface plasmon resonance is strongly induced in a portion of the interface along the direction of the photoelectric field in the photoelectric conversion layer 10. In the strong surface plasmon resonance, the amplitude of the electric field enhanced by the surface plasmon resonance is increased, and the light absorption by the photoelectric conversion layer 10 in the vicinity thereof is also enhanced, so that the interface between the photoelectric conversion layer 10 and the metal structure 50 is inclined. In the photovoltaic element 2000 having the structure as described above, the absorption can be enhanced from the viewpoint of optical action.

[2-2 Example of structure]
In the photoelectric conversion element of this embodiment, in particular, the metal structure can be selected from various structures. FIG. 10 is a perspective view showing the configuration of only the metal structure in some variations of the photoelectric conversion element. Among these, FIG. 10A shows the structure of the metal structure 50 of the photovoltaic element 2000 shown in FIG. FIG. 10B shows the structure of the metal structure 52 in the photovoltaic device 2200 in which the metal structure has only a single inclined plane. FIG. 10C shows a single inclined plane metal structure 52B inclined in a different direction from a single inclined plane metal structure 52A in the photovoltaic element 2200a having metal structures with different inclination directions. It is the structure which has. FIG. 10D shows a structure of the metal structure 52 in the photovoltaic element 2400 having a metal structure in which a plurality of minute inclined planes are combined. FIG. 10E shows the structure of the metal structure 56 in the photovoltaic element 2600 having the metal structure having only a part of the side surface of the truncated cone. In each figure, the description of the photoelectric conversion layer 10, the electrode pair 20 and the like is omitted, and the expansion of the photoelectric conversion layer 10 in the photovoltaic element 2000 of FIG. 9 is performed only for the purpose of facilitating understanding of the three-dimensional shape. The coordinate axes corresponding to the case where the direction is the xy plane and the direction of the thickness D of the photoelectric conversion layer 10 is the z direction from the translucent electrode 22 toward the metal electrode 24 are clearly shown. In addition, a virtual plane parallel to the xy plane is described below each metal structure.

  As described above, the photovoltaic element 2000 described using the metal structure 50 in FIG. 10A as an example is an example of the photoelectric conversion element of the present embodiment. The simplest structure of the metal structure in the photoelectric conversion element of this embodiment is the metal structure 52 of the photovoltaic element 2200 shown in FIG. That is, the interface between the plurality of metal structures 52 and the photoelectric conversion layer 10 is an inclined surface that is inclined from the z direction of the thickness. This inclination is the −x direction in the in-plane direction of the photoelectric conversion layer 10 (the direction of the xy plane) in the setting of the coordinate axes as shown in FIG.

  In the photoelectric conversion element of the present embodiment, more preferably, the interface between the photoelectric conversion layer 10 and the metal structure is inclined separately toward different orientations in the in-plane direction (the xy plane direction) of the photoelectric conversion layer 10. It is preferable to have an inclined surface. This preferred configuration includes, for example, inclined surfaces having different directions, such as metal structures 52A and 52B of the photovoltaic element 2200a shown in FIG. This inclination is the −x direction and the x direction for the metal structures 52A and 52B, respectively.

  The metal structure 54 shown in FIG. 10D is also an example of a configuration specified by another rule. That is, at least a part of the interface between the metal structure 54 and the photoelectric conversion layer 10, for example, the minute inclined planes 542A, 542B, and 542C is a part of the side surface of a polygonal pyramid such as a truncated hexagonal pyramid. . The cone, such as the truncated hexagonal pyramid, typically has an axis that faces the thickness direction of the photoelectric conversion layer 10. By including a part of the side surface of such a cone, the interface between the metal structure and the photoelectric conversion layer 10 can be configured to have a surface inclined in a plurality of directions. An example.

  In the present embodiment, the interface serving as the inclined surface does not necessarily have a finite size spread. In the example, the side surface of the truncated cone of the metal structure 50 shown in FIG. 10A can be defined as a surface formed by connecting inclined surfaces having infinitely small areas with different inclination directions. is there. Therefore, for example, a shape in which an interface obtained by cutting out only a part of the side surface of the truncated cone, such as the metal structure 56 shown in FIG. The structure is suitable.

[2-3 Details of structure]
In the photoelectric conversion element of the present embodiment, it is also preferable that the metal structure is configured to be electrically connected to any one of the electrode pairs 20. FIG. 11 is a cross-sectional view illustrating a structure of a photoelectric conversion element having a metal structure electrically connected to one of the electrodes. Among these, Fig.11 (a)-FIG.11 (d) have respectively shown the photovoltaic elements 2000a-2000d which have the metal structures 50a-50d. Among these, the metal structures 50 a and 50 b are electrically connected to the metal electrode 24, and the metal structures 50 c and 50 d are electrically connected to the translucent electrode 22.

  In these photovoltaic elements 2000a to 2000d, as described in the first embodiment, which shows not only the optical action in the case of the photovoltaic element 2000 shown in FIG. 9, but also a synergistic effect with the optical action. In addition, electrical effects can be expected. For this reason, in the present embodiment, the action of the metal structure also as an electrode gives a particularly advantageous configuration of the photoelectric conversion element.

  The configuration in which the interface between the metal structure and the photoelectric conversion layer 10 is tilted while the metal structure illustrated in FIG. 11 is operated as an electrode is tilted when viewed from the first embodiment. It can be said that the structure is modified. Such a configuration is a particularly advantageous configuration even when viewed from the first embodiment.

[2-4 Manufacturing method]
The manufacturing method of the photovoltaic element 2000 described above is as follows. First, the organic semiconductor photoelectric conversion layer 10 is formed to a certain thickness on the translucent electrode 22 (first electrode layer) formed on the translucent substrate 80. Next, at least a part of the plurality of metal structures 50 in which surface plasmon resonance is induced by light incident on the photoelectric conversion layer 10 is positioned within the thickness range of the photoelectric conversion layer 10. In this step, the inclined surface in which the interface between at least one of the plurality of metal structures 50 and the photoelectric conversion layer 10 is inclined from the thickness direction toward at least a certain direction in the in-plane direction of the photoelectric conversion layer 10. It is made to have. Further, the metal electrode 24 (second electrode layer) is brought into contact with the photoelectric conversion layer 10 so as to sandwich the photoelectric conversion layer 10 in the thickness direction in combination with the translucent electrode 22 (first electrode layer). Form.

  At this time, in order to produce a photoelectric conversion element having the structure of the photovoltaic elements 2000a and 2000b (FIGS. 11A and 11B), the photoelectric conversion layer 10 was exposed from the upper surface on the paper surface. A metal electrode 24 (metal electrode) is formed in contact with the metal structures 50a and 50b. This process is different from the method of manufacturing the photovoltaic element 1000 according to the first embodiment described with reference to FIGS. 5 and 6 in that the shape of the metal structure 50 is different. The conditions are substantially the same except that the condition for electrical connection to the (metal electrode) is not required.

  Further, the following manufacturing method can be employed to produce the photoelectric conversion elements having the structures of the photovoltaic elements 2000c and 2000d (FIGS. 11C and 11D). The photovoltaic element 2000c will be described as an example. At least one of the plurality of metal structures 50c in which surface plasmon resonance is induced by incident light is formed on the light-transmitting substrate 80. It is formed in contact with the photoelectrode 22 (first electrode layer). In this step, the inclined surface in which the interface between at least one of the plurality of metal structures 50c and the photoelectric conversion layer 10 is inclined from the thickness direction toward at least a certain direction in the in-plane direction of the photoelectric conversion layer 10. To have. Next, the organic semiconductor photoelectric conversion layer 10 is formed in contact with the plurality of metal structures 50 c and the translucent electrode 22 (first electrode layer) so as to form a certain thickness from the translucent electrode 22. Finally, in combination with the translucent electrode 22 (first electrode layer), the photoelectric conversion layer 20 is sandwiched in the thickness direction so that the metal electrode 24 (second electrode layer) is brought into contact with the photoelectric conversion layer 10. Form. This manufacturing method is substantially the same except that the shape of the metal structure 50a is different from the manufacturing method of the photovoltaic element according to the first embodiment described with reference to FIG.

[3 Examples]
Next, it demonstrates further in detail based on the Example which actually confirmed the technical effect about 1st Embodiment especially. 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. In the description of the embodiments, the drawings already described are also referred to as appropriate.

[3-1 Example 1]
As Example 1, the inventors of the present application confirmed the effect of the optical action among the electrical action and the optical action, which is the effect of the embodiment of the present invention described above, by experiments. The example sample was a sample piece having the same configuration as that of the photovoltaic element 1000 described in FIGS. 1 and 2. Each sample piece is an example in which the metal structure 30 is formed only on a part of each sample piece so that the difference depending only on the presence or absence of the metal structure 30 can be clearly confirmed. Conditions other than the presence or absence of the metal structure 30 Were matched as much as possible, and portions of the same shape without the metal structure 30 were also formed side by side on the same sample piece, and this portion was used as a control region for the comparative example (see FIG. 13).

  As a specific sample preparation method, the method described in FIG. 5 was adopted except for the last part of the process. The reason for partially differing from FIG. 5 is to confirm the effect of only the optical action, excluding the electrical action. First, a glass plate was prepared as the translucent substrate 80, and ITO (tin-doped indium oxide) was formed as the translucent electrode 22 to a thickness of 300 nm by sputtering. Thereafter, a PEDOT: PSS film was formed as the hole transport layer 12 by contacting the translucent electrode 22. PEDOT: PSS membrane is poly (3,4-ethylenedioxythiophene) -poly (styrenesulfonate) (Poly (3,4-ethylenedithiothiophene) -poly (styrenesulfonate), manufactured by Aldrich) 2.8 wt% aqueous solution (dispersion) 0.5 ml was cast, spin-coated under the conditions of 2000 rpm and 60 seconds, and baked at 130 ° C. for 10 minutes. In addition, the film thickness of the PEDOT: PSS film | membrane in that case was about 30-40 nm. Further, a PCBM: P3HT film was formed as an active layer 14 on the surface of the hole transport layer 12. These conditions were first poly (3-hexylthiophene) (P3HT, average molecular weight 30000, made by Aldrich), and [6,6] -Phenyl C61 butyric acid methyl ester (PCBM, purity> 99.9%, made by Aldrich). A blend solution of P3HT 1.25 wt% and PCBM 1.0 wt% obtained by dissolving each in a dichlorobenzene solution was prepared. Next, 0.25 ml of the blend solution was cast, spin-coated at 1000 rpm for 60 seconds, and heat-treated at 110 ° C. for 10 minutes. At this point, the configuration of FIG. 5A was obtained. The thickness of the PCBM: P3HT film at this time was about 170 nm. Note that PCBM: P3HT operates with PCBM as an acceptor (n-type) and P3HT as a donor (p-type). In addition, the layer of PCBM: P3HT (active layer 14) believes that PCBM and P3HT are separated from each other at least microscopically in some separated structure such as a layered structure or a bulk heterojunction structure. The separation structure has not been confirmed at this time.

  Next, using a cycloolefin polymer (COP) film for imprinting as another substrate 90, a metal structure 30 made of Au (gold) was formed on one surface thereof. The process of forming the metal structure was formed by the method reported by the present inventors in Non-Patent Document 1. The formed Au metal structure is called AuNPs (Au Nanopillars). AuNPs were arranged in a hexagonal close-packed lattice with a center-to-center distance of 450 nm with the nearest neighbor. AuNPs had a bottomless and single cylindrical wall shape with an outer diameter of about 310 nm, a wall thickness of about 55 nm, and a cylindrical shape height of about 100 nm. This AuNPs was used as the metal structure 30.

In FIG. 12, a scanning electron microscope (SEM) photograph showing the arrangement of AuNPs on the temporary substrate 90 is partially enlarged. On the temporary substrate 90, about 1.4 billion AuNPs were formed per 1 cm ² , and most of the individual AuNPs were formed in a good cylindrical wall shape.

  Next, among the surfaces of the active layer 14 of the translucent substrate 80 on which the PEDOT: PSS film (hole transport layer 12) and the PCBM: P3HT layer (active layer 14), which are the photoelectric conversion layer 10, are formed, the metal structure The surface on which AuNPs of the cycloolefin film, which is another substrate 90, was formed was pressed against the region where 30 was formed (FIG. 5B). For this pressing, an imprinting device (Nanoimprinter NM-0401 (manufactured by Myeongchang Kiko Co., Ltd.)) was used, and a pressure in the film thickness direction of 400 N was applied in the range of 10 mm × 10 mm. And in the pressurization state, the metal structure 30 of AuNPs was press-fitted into the photoelectric conversion layer 10 by heating the sample to 100 ° C. for 10 minutes with a hot plate attached to the apparatus. After cooling, the COP film as the separate substrate 90 was easily peeled off (FIG. 5C).

  Here, if the aluminum film is formed as the metal electrode 24 shown in FIG. 5D, for example, a photoelectric conversion element having the structure of the photovoltaic element 1000 shown in FIGS. 1 and 2 can be produced. it can. In the present embodiment, the metal structure 30 and the metal electrode 24 are electrically connected by partially different from the manufacturing process of FIG. 5 in order to exclude the electric action and confirm the effect of only the optical action. I tried not to let it. Specifically, an additional layer of PCBM: P3HT was additionally formed on the surface where the metal electrode 24 was exposed from the photoelectric conversion layer 10 in the state of FIG. The thickness of the additional layer at this time was about 80 nm. Thereafter, an aluminum film was formed on the surface of the additional layer. For this reason, the thickness of PCBM: P3HT including the additional layer was about 250 nm at the time of observation after fracture after embedding of the metal structure 30 described later.

  The aluminum film as the metal electrode 24 was formed to a thickness of about 60 to 80 nm at a film formation rate of 1 to 2 nm / sec by vacuum deposition, and used as a sample of the example. As an example, a plurality of sample pieces were produced in order to increase the reliability of measurement data. The aluminum film was formed in each of the AuNP formation region and the target region in a range of 4 mm in width extending in a direction orthogonal to the ITO formed in 5 mm in FIG. As described above, the control region in which the metal structure 30 is not formed is made as identical as possible including the conditions of the hole transport layer 12 and the active layer 14 and the thermal history. In other words, each sample piece was at least comparable with the control region, and the experiment was such that the reproducibility could be confirmed by a plurality of sample pieces.

  Furthermore, the produced sample piece was observed and measured. Observation and measurement were performed on a completed sample piece and a sample in the middle of preparation. At the beginning, the sample was observed at the stage before the formation of the aluminum film (the stage of FIG. 5C). A monochrome optical photograph of the appearance of the film surface of the sample at this stage and a scanning electron microscope (SEM) photograph of the film surface are shown in FIGS. 13 and 14, respectively. FIG. 13 also includes schematic diagrams showing a range in which AuNPs are formed, a control region in which AuNPs are not placed (a portion serving as a comparative example), an ITO formation range, and an organic semiconductor layer formation range. In the appearance photograph of FIG. 13, a black rectangular area is an area where AuNPs are arranged. In the visual observation, the rectangular area was clearly observed as black, and the area of only the organic semiconductor layer without AuNPs around it was bright red. The SEM photograph of FIG. 14 shows an enlarged top surface of the rectangular region, and the state of AuNPs embedded in the organic semiconductor layer was clearly observed.

  Furthermore, the internal structure of the layer was confirmed for another sample (observation sample) at the stage where an additional layer of PCBM: P3HT was formed. 15 and 16 are SEM photographs taken with the vicinity of the photoelectric conversion layer 10 broken. In FIG. 15, the range of the organic semiconductor layer and AuNPs, the range of ITO, and the range of the glass substrate are added. FIG. 16 also includes an explanatory diagram in which the outline of AuNPs (only three) is added to the SEM photograph taken. From the SEM photograph of FIG. 15, the ITO layer as the translucent electrode 22 and the PCBM: P3HT layer as the active layer 14 can be confirmed, and AuNPs as the metal structure 30 can also be confirmed. In particular, as shown in FIG. 16, AuNPs that are the metal structures 30 are arranged between the translucent electrode 22 and the surface on which the metal electrode 24 will be deposited later, and the active layer 14 forms a gap between the AuNPs. I confirmed that it was buried. The hole transport layer 12 was not clearly confirmed.

Next, two types of optical actions were investigated on the sample in the middle of the production. One is the characteristic of surface plasmon resonance exhibited by AuNPs. FIG. 17 is a graph of the extinction ratio spectrum shown by the array of AuNPs arranged on the COP film, which is the separate substrate 90, used for producing the sample of the example of the present invention. The extinction ratio spectrum was calculated according to the extinction ratio ε = (1−I / I ₀ ) from the transmitted light intensity of the sample at each wavelength. Here, I is the transmitted light intensity of the sample, and I ₀ is the incident light intensity (that is, the transmitted light intensity when the sample is not disposed). As can be seen from the figure, the extinction ratio has a peak for light (infrared rays) with a wavelength of 1300 to 1400 nm, and an extinction spectrum in which surface plasmon resonance is induced for light in the range of approximately 500 nm to 2000 nm is obtained. It was. The other is an absorbance spectrum before and after embedding AuNPs, that is, in two stages of FIG. 5B and FIG. FIG. 18 is a graph of measured values of the absorbance spectrum before and after embedding AuNPs in the sample of the example of the present invention. Curve C1 is the absorbance spectrum before embedding AuNPs, and curve C2 is the respective absorbance spectrum after embedding AuNPs. This comparison highlights the difference in absorption of the photoelectric conversion layer 10 depending on the presence or absence of the metal structure 30, that is, AuNPs, and shows how surface plasmon resonance actually enhances the absorption of the photoelectric conversion layer 10.

  Specifically, from the curve C1, in the visible region, an absorption spectrum that explains the red appearance observed in the portion where AuNPs are not arranged, that is, in the visible region (380 nm to 780 nm), in the shorter wavelength region than near 650 nm. Strong absorption and weak absorption in a long wavelength region from around 650 nm were confirmed. In the near-infrared region of 780 nm to 2000 nm, absorption having a broad peak around 1400 nm can be confirmed. After embedding AuNPs, the absorption spectrum changed to a curve C2, and the absorption was enhanced in the entire wavelength region measured. More specifically, the absorption increased in the entire visible range, and in particular, the absorption increased in the wavelength region longer than 650 nm, which had been weak until then, and a peak was observed at about 750 nm. This change in the visible region also coincides with the fact that the rectangular region (FIG. 13) where AuNPs are not arranged is visually recognized as black. Furthermore, the absorption increased greatly in the entire infrared region. In particular, the absorption was strong and weak, and broad absorption peaks having peaks near 1200 nm and 1700 nm were generated.

  The inventors of the present application believe that the absorption enhanced by embedding AuNPs is due to surface plasmon resonance. In particular, as shown in FIG. 18, the absorbance increased at the present time in the entire wavelength range, and in particular, the increase in absorbance was remarkable in the infrared region exceeding 800 nm, which is a longer wavelength region than the visible wavelength. . In particular, the peak in FIG. 18 is considered to be a dipole component having an electromagnetic radiation component with respect to a far field in surface plasmon resonance, in which 1700 nm is a symmetric mode and 1200 nm is an asymmetric mode from the long wavelength side. ing. Note that the symmetric mode refers to surface plasmons induced on both sides of the wall of the metal structure (for example, the outer surface 302 and the inner surface 304 at the same azimuth as viewed from the central axis of the cylinder of the metal structure 30). The vibration mode is a vibration mode in which the combination of charge signs on both sides is the same sign, and the asymmetric mode is a vibration mode in which the sign is opposite. In addition, although the peak at about 750 nm in the visible range is thought to be possibly derived from a hexagonal close-packed lattice pattern with a pitch of 450 nm of AuNPs, it cannot be accurately identified.

And it was made to operate | move as a solar cell using the sample piece formed and completed to the metal electrode 24 of FIG.5 (d), and measured the current-voltage characteristic by photoelectric conversion. FIG. 19 is a graph obtained by measuring the current-voltage characteristics of a sample piece according to an embodiment of the present invention for a portion where no AuNPs are arranged (curve D1) and a portion where the AuNPs are arranged (curve D2). In the portion where the AuNPs are not arranged as shown by the curve D1, the open circuit voltage was 0.47 V and the short circuit current was 27 μA / cm ² . On the other hand, the open circuit voltage was 0.40 V and the short-circuit current was 71 μA / cm ² in the portion where AuNPs was arranged from the curve D2. Furthermore, Table 1 summarizes the fill factor (FF) and photoelectric conversion efficiency η determined from these current-voltage characteristics.

  Further, the current-voltage characteristics were measured and measured for a plurality of samples that were manufactured by the above-described process and could be compared for the presence or absence of AuNPs, and the photoelectric conversion efficiency η was calculated. FIG. 20 shows, for each sample piece, the photoelectric conversion efficiency η, the part of the comparative example (square mark) in which AuNPs is not provided in the thickness range of the photoelectric conversion layer 10, and the part of the example in which AuNPs is provided (circle mark). It is the graph which plotted and. The sample pieces were four pieces distinguished by sample numbers 1 to 4. 19 and Table 1 are based on the measurement result of sample number 1.

  As shown in FIG. 20, in all comparable sample pieces, the photoelectric conversion efficiency η is at least as compared with the comparative example part in which AuNPs is not provided in the thickness range of the photoelectric conversion layer 10. It was confirmed that it increased to 2 times, or about 10 times depending on the sample. Thus, this example confirmed that the optical action in the first embodiment of the present invention, that is, the effect of increasing absorption by surface plasmon resonance actually improves the photoelectric conversion characteristics.

[3-2 Example 2]
Next, a metal structure for the second embodiment of the present invention was produced. A metal structure having a structure similar to that of the metal structure 52A and the metal structure 52B shown in FIG. 10C having different inclination directions was manufactured by the same method as in Example 1 for the first embodiment. 21 and 22 are SEM photographs of these metal structures. FIG. 21 shows a height of about 100 nm, and FIG. 22 shows a height of about 350 nm. In both cases, like the metal structure 52A and the metal structure 52B, they are inclined in directions different from each other by 180.degree. It was configured to make. Since both surfaces of the surface of the metal structure shown in FIGS. 21 and 22 are inclined, if the photoelectric conversion element of the second embodiment is manufactured, the interface between the photoelectric conversion layer 10 and the metal structure can be inclined. Is possible.

[3-3 Summary of Examples]
As described above, in Example 1, the effect of increasing the photoelectric conversion efficiency can be clearly confirmed only by the optical action. This is because the increase in absorption of the photoelectric conversion layer 10 by surface plasmon resonance improves the efficiency of the photovoltaic device. It demonstrates that it has a significant contribution to improvement.

  Furthermore, the relationship between the increase in absorbance in the entire wavelength range measured as shown in FIG. 18 and the fact that the power generation efficiency could actually be increased is at least due to surface plasmons. This suggests that further improvement to the effect of improving the efficiency of the photovoltaic element that can be performed by an optical function is possible. If this point is demonstrated in detail, the photoelectric converting layer 10 which isolate | separates a carrier from the exciton in an organic semiconductor and generates electric power uses the light of the wavelength range of 750 nm or less for electric power generation. From FIG. 18, the increase in absorbance in this wavelength region is not as significant as the increase in absorbance in the infrared. Nevertheless, the above-described clear and reproducible efficiency improvement effect is obtained. In other words, there is still room for improvement in the metal structure 30 in the photovoltaic element 1000. A typical improvement is that the wavelength at which the peak of plasmon resonance is obtained is in the visible wavelength range, more precisely, the wavelength range in which the photoelectric conversion layer 10 can perform power generation operation with high efficiency, and the wavelength of irradiated light is strong. What happens in the range. It is also a preferable improvement to increase the absorption in the wavelength region where the wavelength is at least shorter than the present time and the photoelectric conversion layer 10 becomes highly efficient by approaching these wavelength ranges. Adjustment of the wavelength of plasmon resonance such as these, particularly shortening of the wavelength, for example, further miniaturizes the size of the metal structure 30 or changes the material of the metal structure 30 from Au, which is currently employed, to aluminum. This can be achieved by modification from the configuration of the first embodiment.

  The inventors of the present application are convinced that an electrical action, that is, an effect of increasing the area of the electrode and an effect of shortening the distance are also realized. For example, the area of the inner side surface and the outer side surface of the cylindrical wall of AuNPs produced in the example sample is approximately the same as the area of the metal electrode 24. For this reason, when AuNPs is actually brought into contact with the metal electrode 24, the electrode area can be doubled. It can be said that this difference in area can sufficiently expect the area increasing effect. Further, the effect of shortening the distance can be sufficiently expected if the size and shape of AuNPs in which surface plasmon resonance is induced are taken into consideration.

  Furthermore, what was confirmed in Example 1 above is the photoelectric conversion efficiency of the photovoltaic element when used as a solar cell, but also when the photovoltaic element is used as, for example, a light detection unit of a photosensor, The effect of increasing the current value accompanying the detection of light and the effect of increasing the sensitivity as a result can be expected.

  In addition, regarding Example 2 above, it is clearly shown that the metal structure for the second embodiment can actually be fabricated. And since the specific production method of the photoelectric conversion element demonstrated by Example 1 is applicable also when employ | adopting the metal structure described in Example 2, the photoelectric conversion element of 2nd Embodiment is also produced without trouble. can do.

  The photovoltaic element according to 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 claims. Moreover, the modification which exists in the scope of the present invention including other combinations of each embodiment is also included in a claim.

  The photovoltaic element of the present invention can be used in any device that uses, for example, a solar cell or a photosensor.

1000, 1000a, 1100, 1100a, 1200, 1300 Photovoltaic element 2000, 2000a to d, 2400, 2600 Photovoltaic element 10 Photoelectric conversion layer 10A Precursor film 12 Hole transport layer 14 Active layer 14A Precursor film 14C Microstructure 14B Base part 14D Organic semiconductor 16 Micro temporary structure 20 Electrode pair 20 Photoelectric conversion layer 22 Translucent electrode 24 Metal electrode 30, 32, 34, 36 Metal structure 302, 322 Outer side surface 304, 324 Inner side surface 34A, 36A Inner cylinder Wall 34B, 36B Outer cylindrical wall 40, 42 Oxide film 50, 50a, 50b, 50c, 50d Metal structure 502 Outer surface 504 Inner surface 52, 52A, 52B, 54 Metal structure 542A, 542B, 542C Slightly inclined plane 56 Metal Structure 80 Translucent substrate 90 Separate substrate 9 2 Imprint type

Claims (18)

A photoelectric conversion layer of an organic semiconductor of a certain thickness;
The photoelectric conversion layer is opposed across the thickness direction, and at least one is a translucent electrode,
A plurality of metal structures that cause surface plasmon resonance to be induced by light incident on the photoelectric conversion layer, and at least a part of the plurality of metal structures is at least partially in the photoelectric conversion layer. A photovoltaic device that is located in the thickness range of the electrode pair and is electrically connected to one of the electrodes of the electrode pair. One of the electrode pairs is the translucent electrode and the other is a metal electrode,
The photovoltaic element according to claim 1, wherein the at least one of the plurality of metal structures is electrically connected to the metal electrode.   The photovoltaic element according to claim 1, wherein the at least one of the plurality of metal structures is electrically connected to the translucent electrode of the electrode pair.   The at least one of the plurality of metal structures has an outer surface or an inner surface having a component extending in the thickness direction, and at least one of the outer surface or the inner surface is for the photoelectric conversion layer. The photovoltaic element according to claim 1, which operates as an electrode.   The at least one of the plurality of metal structures is formed on at least a part of a surface facing the other electrode of the electrode pair facing the one electrode electrically connected to the metal structure. The photovoltaic element according to claim 1, wherein an oxide of the material is formed.   An interface between at least one of the plurality of metal structures and the photoelectric conversion layer has an inclined surface inclined from the direction of the thickness toward at least a certain direction in an in-plane direction of the photoelectric conversion layer. The photovoltaic element according to claim 1, wherein A photoelectric conversion layer of an organic semiconductor of a certain thickness;
The photoelectric conversion layer is opposed across the thickness direction, and at least one is a translucent electrode,
A plurality of metal structures that cause surface plasmon resonance to be induced by light incident on the photoelectric conversion layer, and at least a part of the plurality of metal structures is at least a part of the photoelectric conversion layer. In the thickness range of
The interface between the at least one of the plurality of metal structures and the photoelectric conversion layer has an inclined surface inclined from the thickness direction toward at least a certain direction in the in-plane direction of the photoelectric conversion layer. A photovoltaic element.   The photovoltaic element according to claim 7, wherein the interface has different inclined surfaces inclined toward different orientations in an in-plane direction of the photoelectric conversion layer. At least a part of the interface forms a side part of a cone having an axis facing the thickness direction of the photoelectric conversion layer;
The photovoltaic element according to claim 7 or 8, wherein the at least part of the interface includes the separate inclined surfaces.   The photovoltaic element according to claim 7, wherein at least one of the plurality of metal structures is electrically connected to any electrode of the electrode pair.   The photovoltaic device according to claim 1 or 7, wherein the plurality of metal structures are ones in which the surface plasmon resonance is induced in a range of a light absorption wavelength of a material of the photoelectric conversion layer. On the first electrode layer formed on the substrate, an organic semiconductor photoelectric conversion layer having a certain thickness, and a plurality of metal structures in which surface plasmon resonance is induced by light incident on the photoelectric conversion layer; An arrangement step of disposing at least a part of the plurality of metal structures in a range of the thickness of the photoelectric conversion layer;
A second electrode layer is formed by contacting at least one of the plurality of metal structures and the photoelectric conversion layer so as to sandwich the photoelectric conversion layer in the thickness direction in combination with the first electrode layer A process for producing a photovoltaic device comprising the steps of: The arrangement step includes
Forming a photoelectric conversion layer with a uniform thickness on the first electrode layer;
The method for producing a photovoltaic device according to claim 12, further comprising: softening the photoelectric conversion layer and pressing the plurality of metal structures into the softened photoelectric conversion layer. The arrangement step includes
Forming a microstructure with the organic semiconductor while covering the surface of the first electrode layer;
Forming a metal film to be in contact with the surface of the microstructure to form the plurality of metal structures;
The step of filling the organic semiconductor in the gap between the plurality of metal structures, and the photoelectric conversion layer of the microstructure and the photoelectric conversion layer together perform photoelectric conversion. A method for manufacturing a power element. The step of bringing at least one of a plurality of metal structures whose surface plasmon resonance is to be induced by incident light into contact with the first electrode layer formed on the substrate to form the plurality of metal structures When,
Forming the photoelectric conversion layer of an organic semiconductor in contact with the plurality of metal structures and the first electrode layer so as to form a certain thickness from the first electrode layer;
A step of forming a second electrode layer in contact with the photoelectric conversion layer so as to sandwich the photoelectric conversion layer in the thickness direction in combination with the first electrode layer. Method. The step of forming the plurality of metal structures includes:
Forming an organic semiconductor microstructure on the first electrode layer;
Forming a metal film that is in contact with the surface of the microstructure and connected to the first electrode layer to form the plurality of metal structures,
The method for producing a photovoltaic element according to claim 15, wherein the microstructure and the photoelectric conversion layer both perform photoelectric conversion. Forming an organic semiconductor photoelectric conversion layer in a certain thickness on the first electrode layer formed on the substrate;
A step of positioning at least a part of a plurality of metal structures in which surface plasmon resonance is induced by light incident on the photoelectric conversion layer in the thickness range of the photoelectric conversion layer, wherein the plurality of metals A step in which an interface between at least one of the structures and the photoelectric conversion layer has an inclined surface inclined from the direction of the thickness toward at least a certain direction in an in-plane direction of the photoelectric conversion layer. When,
A step of forming a second electrode layer in contact with the photoelectric conversion layer so as to sandwich the photoelectric conversion layer in the thickness direction in combination with the first electrode layer. Method. The step of bringing at least one of a plurality of metal structures whose surface plasmon resonance is to be induced by incident light into contact with the first electrode layer formed on the substrate to form the plurality of metal structures An inclined surface in which an interface between at least one of the plurality of metal structures and the photoelectric conversion layer is inclined from the thickness direction toward at least a certain direction in an in-plane direction of the photoelectric conversion layer. Having a process, and
Forming the photoelectric conversion layer of an organic semiconductor in contact with the plurality of metal structures and the first electrode layer and forming a certain thickness from the first electrode layer;
A step of forming a second electrode layer in contact with the photoelectric conversion layer so as to sandwich the photoelectric conversion layer in the thickness direction in combination with the first electrode layer. Method.