JP2010258205A - Manufacturing method of organic photoelectric conversion element, and the organic photoelectric conversion element manufactured by the manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an organic photoelectric conversion element forming a more dense film with high coverage even on a greatly uneven electrode surface. <P>SOLUTION: In the manufacturing method of the organic photoelectric conversion element including a bulk hetero-junction type photoelectric conversion layer sandwiched between first and second electrodes made of a metal A and a positive hole carrier layer or an electron carrier layer, the manufacturing method of the organic photoelectric conversion element is characterized in that the step of forming the positive hole carrier layer or the electron carrier layer includes the steps of covering the first electrode with a substance containing a metal B which is different from the metal A, and oxidizing the metal B containing substance and the organic photoelectric conversion element is manufactured by the above manufacturing method. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for producing an organic photoelectric conversion element and an organic photoelectric conversion element produced by the production method.

  Organic solar cells are attracting attention as solar cells suitable for mass production because they can be formed by a coating method, and many research institutions are actively researching them. In organic solar cells, charge separation efficiency, which has been a problem, is improved by a so-called bulk heterojunction structure in which an organic donor material and an organic acceptor material are mixed. As a result, the energy conversion efficiency is improved to the 5% level, which can be said to be a field that has been developed to a practical level at once (for example, see Patent Document 1).

  In an organic photoelectric conversion element, a hole transport layer that makes it easy to selectively pass holes and makes it difficult for electrons to pass between a first electrode that becomes an anode and an active layer that becomes a photoelectric conversion layer, and a second that becomes a cathode A proposal has been made to improve the photoelectric conversion efficiency by introducing an electron transport layer between the electrode and the photoelectric conversion layer, which facilitates the selective passage of electrons and prevents the passage of holes. Among them, methods for forming PEDOT as a hole transport layer and TiOx as an electron transport layer by a coating method have been proposed (see Patent Documents 2 and 3). A hole transport layer and an electron transport layer obtained by these coating methods are proposed. Has a problem that the density of the obtained film is low and the carrier selectivity is not sufficient. In addition, when an attempt is made to coat the surface of an electrode with large surface irregularities such as conductive fibers and metal nanorods, there is a practical problem that it is difficult to coat along the irregularities and the coverage of the electrode is low.

US Pat. No. 5,331,183 JP 2007-273929 A WO 2004-017422 A2 pamphlet

  As described above, none of the conventionally proposed techniques can solve the problem of obtaining a hole transport layer or an electron transport layer satisfying various characteristics. Accordingly, an object of the present invention is to provide a method for producing an organic photoelectric conversion element in which a dense film is formed at a high coverage even on an electrode surface having large surface irregularities.

  The above object of the present invention can be achieved by the following configuration.

  1. In the method for producing an organic photoelectric conversion element having a bulk heterojunction photoelectric conversion layer sandwiched between a first electrode and a second electrode, and a hole transport layer or an electron transport layer, the first electrode is a metal A And the step of forming the hole transport layer or the electron transport layer comprises a step of coating a material containing a metal B different from the metal A or a metal B on the first electrode, A process for oxidizing the metal B, and a method for producing an organic photoelectric conversion element.

  2. 2. The method for producing an organic photoelectric conversion element according to 1 above, wherein the metal B is supplied from a metal salt compound containing the metal B.

  3. 3. The method according to 1 or 2, wherein the step of coating the substance containing metal B or metal B includes the step of oxidizing the metal B after forming the first electrode made of the metal A. Manufacturing method of the organic photoelectric conversion element.

  4). 4. The method for producing an organic photoelectric conversion element according to any one of 1 to 3, wherein the step of coating the metal B uses a plating method.

  5. 5. The method for producing an organic photoelectric conversion element according to any one of 1 to 4, wherein the step of oxidizing the substance containing the metal B uses atmospheric pressure plasma.

  6). Any one of 1 to 5 above, wherein the layer between at least one of the first electrode and the second electrode and the bulk heterojunction layer is at least one of a hole transport layer and an electron transport layer. The manufacturing method of the organic photoelectric conversion element of item 1.

  7). 7. The method for producing an organic photoelectric conversion element according to any one of 1 to 6, wherein the metal B includes at least one of Ti, Ni, Cu, and Zn.

  8). 8. The method for producing an organic photoelectric conversion element according to any one of 1 to 7, wherein the surface of the first electrode has irregularities.

  9. 9. The method for producing an organic photoelectric conversion element according to any one of 1 to 8, wherein the metal A forming the first electrode includes at least one of a conductive fiber and a nanorod.

  10. 10. The method for producing an organic photoelectric conversion element according to 9, wherein the conductive fiber includes at least one of a metal nanowire and a carbon nanotube.

  11. 11. The method for producing an organic photoelectric conversion element as described in 10 above, wherein the metal nanowire is a silver nanowire.

  12 The organic photoelectric conversion element manufactured by the manufacturing method of the organic photoelectric conversion element of any one of said 1-11.

  According to the present invention, a hole transport layer and an electron transport layer are formed by forming a metal on an electrode by a plating method and oxidizing the surface with atmospheric pressure plasma so that the density of the formed film is high and carrier separation ability is excellent. Could be formed. In addition, according to the present invention, a hole transport layer and an electron transport layer can be formed with a high coverage even on electrodes having large surface irregularities such as conductive fibers and metal nanorods.

It is a schematic sectional drawing which shows the basic structure of the bulk heterojunction type photoelectric conversion element of this invention. It is a schematic sectional drawing which shows the preferable structure of the bulk hetero junction type photoelectric conversion element of this invention. It is the schematic which shows an example of the atmospheric pressure plasma discharge processing apparatus which has a rotating electrode and a fixed electrode. It is a perspective view which shows an example of the structure of the electroconductive metal base material of a roll rotating electrode, and the dielectric material coat | covered on it. It is a perspective view which shows an example of the structure of the electroconductive metal preform | base_material of a rectangular tube type electrode, and the dielectric material coat | covered on it.

  As described above, the hole transport layer or the electron transport layer formed by the conventional coating method has a low film density and insufficient carrier separation ability. There was a problem that the rate was low, which was a practical problem. Therefore, the present inventor coated a metal thin film on the surface of the first electrode by a plating method, and further oxidized the metal by an atmospheric pressure plasma method. The inventors have found that a hole transport layer and an electron transport layer can be formed, and have reached the present invention.

  Hereinafter, configurations that can be preferably used in the present invention will be described in detail.

[Organic photoelectric conversion element]
The photoelectric conversion element of the present invention will be described in detail with reference to FIG. FIG. 1 is a schematic cross-sectional view showing the basic structure of a bulk heterojunction photoelectric conversion device of the present invention.

  In FIG. 1, a bulk heterojunction organic photoelectric conversion element includes a first electrode 12 and a photoelectric conversion layer 13 having a bulk heterojunction structure (a p-type semiconductor layer and an n-type semiconductor layer) on one surface of a substrate 11 (hereinafter, referred to as “a heterostructure”). 1) and the second electrode 14 are sequentially stacked as shown in FIG. Furthermore, an intermediate layer may be provided between the first electrode 12 and the photoelectric conversion layer 13 and / or between the photoelectric conversion layer 13 and the second electrode 14. As a preferable form of the intermediate layer, a hole transport layer is laminated between the photoelectric conversion layer 13 and the first electrode 12, and an electron transport layer is laminated between the photoelectric conversion layer 13 and the second electrode 14. It is preferable. The present invention is characterized in that in the bulk heterojunction organic photoelectric conversion element, the first electrode is formed by coating the surface of the conductive fiber with an oxide of a metal different from the conductive fiber. .

  The method for producing the organic photoelectric conversion device according to the present invention will be described in detail with reference to FIG. After applying conductive fibers on the substrate 21, the metal oxide is coated by an atmospheric pressure plasma method to form the first electrode 22 and the hole transport layer 23, and a p-type semiconductor and an n-type semiconductor are formed thereon. It is preferable to produce an organic photoelectric conversion element by sequentially laminating a photoelectric conversion layer 24 and an electron transport layer 25 containing materials to form a second electrode 26. The hole transport layer 23 and the electron transport layer 25 can be preferably used in the present invention even if they have opposite configurations.

  Hereinafter, preferred configurations of the present invention will be described.

[First electrode]
The cathode and anode of the first electrode of the present invention are not particularly limited and can be selected depending on the element configuration. For example, when used as an anode, the first electrode 12 is preferably an electrode that transmits light of 300 to 800 nm. As materials, for example, transparent conductive metal oxides such as indium tin oxide (ITO), SnO2, and ZnO, metal thin films such as gold, silver, and platinum, metal nanowires, carbon nanotubes, and conductive polymers can be used. Moreover, you may comprise combining them. Furthermore, the total light transmittance of the first electrode is preferably 60% or more, more preferably 70% or more, and particularly preferably 80% or more. The total light transmittance can be measured according to a known method using a spectrophotometer or the like. In addition, the electrical resistance value of the first electrode of the present invention is preferably 50Ω / □ or less, more preferably 10Ω / □ or less, and particularly preferably 3Ω / □ or less as the surface resistivity. preferable. If it is 50 ohms / square or less, since sufficient photoelectric conversion efficiency is obtained also in an organic photoelectric conversion element with a large light-receiving area, it is preferable. The surface resistivity can be measured in accordance with, for example, JIS K 7194: 1994 (resistivity test method using a conductive plastic four-probe method), and can be easily performed using a commercially available surface resistivity meter. Can be measured. In the bulk heterojunction type organic photoelectric conversion element 10 shown in FIG. 1, the photoelectric conversion layer 13 is sandwiched between the first electrode 12 and the second electrode 13. The back contact type organic photoelectric conversion element 10 may be configured such that it is disposed on one side of the layer 13. The thickness of the first electrode of the present invention is not particularly limited and can be appropriately selected according to the purpose. Generally, it is preferably 10 μm or less, and the transparency and flexibility are improved as the thickness is reduced. Therefore, it is more preferable.

[Conductive fiber]
The conductive fiber according to the present invention is conductive and has a shape whose length is sufficiently longer than its diameter (thickness). The conductive fiber according to the present invention is considered to function as an auxiliary electrode by forming a three-dimensional conductive network when the conductive fibers contact each other in the transparent conductive layer. Accordingly, a longer conductive fiber is preferable because it is advantageous for forming a conductive network. On the other hand, when the conductive fibers are long, the conductive fibers are entangled to form aggregates, which may deteriorate the optical characteristics. Since the conductive fiber formation and aggregate formation are also affected by the stiffness and diameter of the conductive fibers, use the one with the optimum average aspect ratio (aspect = length / diameter) according to the conductive fibers used. Is preferred. As a rough guide, the average aspect ratio is preferably 10 to 10,000.

  Examples of the shape include a hollow tube shape, a wire shape, and a fiber shape, such as organic fibers and inorganic fibers coated with metal, conductive metal oxide fibers, metal nanowires, carbon fibers, and carbon nanotubes. In the present invention, from the viewpoint of transparency, it is preferable that the conductive fiber has a thickness of 300 nm or less, and in order to satisfy the conductivity, the conductive fiber is at least selected from the group of metal nanowires and carbon nanotubes. One type is preferable. Furthermore, silver nanowires are particularly preferable from the viewpoints of cost (raw material costs, manufacturing costs) and performance (conductivity, transparency, flexibility).

[Metal nanowires]
In general, the metal nanowire refers to a linear structure having a metal element as a main component. In particular, the metal nanowire in the present invention means a linear structure having a diameter from the atomic scale to the nm scale.

  As the metal nanowire applied to the conductive fiber according to the present invention, in order to form a long conductive path with one metal nanowire, the average length is preferably 3 μm or more, more preferably 3 to 500 μm, In particular, the thickness is preferably 3 to 300 μm. In addition, the relative standard deviation of the length is preferably 40% or less. Moreover, it is preferable that an average diameter is small from a transparency viewpoint, On the other hand, the larger one is preferable from an electroconductive viewpoint. In this invention, 10-300 nm is preferable as an average diameter of metal nanowire, and it is more preferable that it is 30-200 nm. In addition, the relative standard deviation of the diameter is preferably 20% or less.

  There is no restriction | limiting in particular as a metal composition of the metal nanowire which concerns on this invention, Although it can comprise from the 1 type or several metal of a noble metal element and a base metal element, noble metals (for example, gold, platinum, silver, palladium, rhodium, (Iridium, ruthenium, osmium, etc.) and at least one metal belonging to the group consisting of iron, cobalt, copper, and tin is preferable, and at least silver is more preferable from the viewpoint of conductivity. Further, in order to achieve both conductivity and stability (sulfurization and oxidation resistance of metal nanowires and resistance to magnation), silver and at least one metal belonging to a noble metal other than silver can be included. When the metal nanowire according to the present invention includes two or more kinds of metal elements, for example, the metal composition may be different between the surface and the inside of the metal nanowire, and the entire metal nanowire has the same metal composition. Also good.

  In the present invention, the means for producing the metal nanowire is not particularly limited, and for example, known means such as a liquid phase method and a gas phase method can be used. Moreover, there is no restriction | limiting in particular in a specific manufacturing method, A well-known manufacturing method can be used. In particular, Adv. Mater. , 2002, 14, 833-837 and Chem. Mater. 2002, 14, 4736-4745, the method for producing Ag nanowires can easily produce Ag nanowires in an aqueous system. Since the electrical conductivity of silver is the largest among metals, it can be preferably applied as the metal nanowire according to the present invention.

〔carbon nanotube〕
A carbon nanotube is a carbon-based fiber material having a shape in which a graphite-like carbon atomic plane (graphene sheet) having a thickness of several atomic layers is wound in a cylindrical shape. Single-walled nanotubes (SWCNT) and multi-layers are formed from the number of peripheral walls. They are roughly classified into nanotubes (MWCNT), and are divided into chiral (helical), zigzag and armchair types according to the difference in the structure of the graphene sheet, and various types are known.

  As the carbon nanotube applied to the conductive fiber according to the present invention, any type of carbon nanotube can be used, and a mixture of these various carbon nanotubes may be used. An excellent single-walled carbon nanotube is preferable, and a metallic armchair-type single-walled carbon nanotube is more preferable.

  The shape of the carbon nanotube according to the present invention is preferably a single-walled carbon nanotube having a large aspect ratio (= length / diameter), that is, a thin and long carbon nanotube, in order to form a long conductive path with one carbon nanotube. . For example, carbon nanotubes having an aspect ratio of 102 or more, preferably 103 or more can be mentioned. The average length of the carbon nanotubes is preferably 3 μm or more, more preferably 3 to 500 μm, and particularly preferably 3 to 300 μm. In addition, the relative standard deviation of the length is preferably 40% or less. Moreover, it is preferable that an average diameter is smaller than 100 nm, 1-50 nm is preferable and it is more preferable that it is 1-30 nm. In addition, the relative standard deviation of the diameter is preferably 20% or less.

  The production method of the carbon nanotube used in the present invention is not particularly limited, and catalytic hydrogen reduction of carbon dioxide, arc discharge method, laser evaporation method, CVD method, vapor phase growth method, high temperature and high pressure of carbon monoxide. Well-known means such as HiPco method in which the reaction is carried out together with an iron catalyst and grown in the gas phase can be used. Moreover, in order to remove residues such as by-products and catalytic metals, carbon nanotubes that have been further purified by various purification methods such as washing methods, centrifugal separation methods, filtration methods, oxidation methods, chromatographic methods, etc. Is more preferable because various functions can be sufficiently expressed.

  As a preferable method for forming a transparent conductive layer containing conductive fibers and a conductive material, a conductive fiber dispersion is applied or printed on the element and dried to form a conductive network structure made of conductive fibers. Next, a method is preferred in which a transparent conductive material is impregnated in the gaps on the network structure of the conductive fibers to form a transparent conductive layer containing the conductive fibers and the transparent conductive material.

[Metal oxide]
Examples of the metal oxide that can be used in the present invention include Li, Be, B, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, and Zn. , Ga, Ge, Rb, Sr, Y, Zr, Nb, Mo, Cd, In, Ir, Sn, Sb, Cs, Ba, La, Hf, Ta, W, Tl, Pb, Bi, Ce, Pr, Nd , Pm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, preferably molybdenum, nickel, silicon, zirconium, titanium, tungsten, tantalum, aluminum, copper, zinc, It contains at least one element of indium, chromium, vanadium, niobium, gallium and tin. More preferably, it has at least one element among silicon, titanium, tin, zinc, and indium. These metals can be used alone or in combination of two or more. For example, barium titanate, SrTiO ₃ , PZT and the like can be mentioned. Moreover, it can also use combining an alkali metal and another metal. The metal oxide may be basically crystalline or amorphous, but is preferably crystalline. The crystalline material may be one or more single crystals, polycrystal, one or more semi-crystalline substances having an amorphous part and a crystalline part at the same time, or a mixture thereof. A single crystal is particularly preferable.

  If the surface of the conductive fiber is covered with a metal oxide of a p-type semiconductor, the formed conductive path functions as a hole transport layer (HTL). Any metal oxide can be used as long as it is a p-type semiconductor material. For example, metal oxides such as molybdenum oxide, nickel oxide, tungsten oxide, and copper oxide can be used.

  If the surface of the conductive fiber is covered with a metal oxide of an n-type semiconductor, the formed conductive path exhibits a function as an electron transport layer (ETL). Any metal oxide can be used as long as it is an n-type semiconductor material. For example, metal oxides such as titanium oxide, zinc oxide, and gallium oxide can be used.

  The hole transport layer and the electron transport layer are layers that mainly flow one of holes and electrons, and the reverse due to the difference in mobility between holes and electrons and the barrier due to the difference in energy levels. A layer that blocks charges is preferable.

(Hole transport layer)
Examples of the material preferably used as the hole transport layer (electron block layer) include PEDOT such as the trade name BaytronP, polyaniline and its doped material, and triarylamine described in JP-A No. 5-271166. Further, a cyanide compound described in WO2006019270 or a metal oxide such as molybdenum oxide, nickel oxide, or tungsten oxide can be used. Moreover, the layer which consists of a p-type semiconductor material single-piece | unit used for the bulk heterojunction layer can also be used. The means for forming these layers is preferably formed by a solution coating method.

(Electron transport layer)
As the electron transport layer (hole blocking layer), octaazaporphyrin, p-type semiconductor perfluoro (perfluoropentacene, perfluorophthalocyanine, etc.), naphthalenetetracarboxylic anhydride, naphthalenetetracarboxylic diimide, perylenetetra N-type semiconductor materials such as carboxylic acid anhydrides and perylenetetracarboxylic acid diimides, and n-type inorganic oxides such as titanium oxide, zinc oxide and gallium oxide, and alkali metal compounds such as lithium fluoride, sodium fluoride and cesium fluoride Etc. can be used. A layer made of a single n-type semiconductor material used for the bulk heterojunction layer can also be used.

  The method for forming the layer covering the surface of the first electrode of the present invention may be any method as long as it is a metal oxide layer containing a carbon element, such as a coating method, a vapor deposition method, a sputtering method, a spray pyrolysis method, A low pressure plasma CVD method, an atmospheric pressure plasma CVD method, or the like can be used. In order to obtain high productivity using a flexible substrate, a method suitable for a continuous process is more preferable, among which a coating method, a spray pyrolysis method, and an atmospheric pressure plasma CVD method are preferable, from the viewpoint of continuous productivity and film quality. Atmospheric pressure plasma CVD is most preferred.

  When the metal oxide layer is formed using the atmospheric pressure plasma CVD method, the method for controlling the carbon element ratio in the layer includes the type of discharge (carrier) gas, the concentration of the reactive gas used as a raw material, and the flow rate, which will be described later. It can be controlled by adjusting the frequency and power applied to the first electrode and the second electrode.

[Plasma discharge treatment]
Hereinafter, the atmospheric pressure plasma method will be described.

  The atmospheric pressure plasma method is a method in which a thin film such as a metal oxide is formed by discharging at atmospheric pressure or near atmospheric pressure to excite a reactive gas and introducing a reactive gas onto the surface of a substrate. For example, they are introduced in JP-A-11-133205, JP-A-2000-185362, JP-A-11-61406, JP-A-2000-147209, 2000-121804, and the like. The atmospheric pressure plasma method disclosed in these publications generates a discharge plasma that is pulsed between opposing electrodes, has a frequency of 0.5 to 100 kHz, and an electric field strength of 1 to 100 V / cm. That's it.

  In the present invention, the plasma discharge treatment is performed under atmospheric pressure or a pressure in the vicinity thereof, and the atmospheric pressure or the pressure in the vicinity thereof is about 20 kPa to 110 kPa, and in order to obtain a good effect described in the present invention. Is preferably 93 kPa to 104 kPa.

In the present invention, the atmospheric pressure plasma discharge treatment is performed by using a rare gas such as helium or argon as a discharge gas and applying a high-frequency electric field exceeding 100 kHz and up to about 150 MHz, preferably about several hundred kHz to 100 MHz. Is called. In the present invention, the power to be supplied varies greatly depending on the type of discharge gas used. In particular, the lower limit value of the power supplied between the electrodes is preferably 0.01 W / cm ² or more, and the upper limit value is preferably 20 W / cm ² or less. More preferably, it is 10 W / cm ² or less. The voltage application area (/ cm ² ) at the electrode refers to the area where discharge occurs.

  In order to generate plasma, it is necessary to discharge in an atmosphere of an inert gas as a carrier gas. Here, the inert gas is a group 18 element of the periodic table, so-called rare gas, helium, Neon, argon, krypton, xenon, radon and the like are preferably used in a nitrogen gas atmosphere, and argon or helium is particularly preferably used. However, it is most preferable to use nitrogen gas from the viewpoint of reducing manufacturing costs.

  In the present invention, as the gas supplied to the discharge space, oxygen, ozone, hydrogen peroxide or the like is used as a reactive gas in addition to the discharge gas.

  The discharge condition in the present invention is that a high frequency voltage is applied to the discharge space between the first electrode and the second electrode facing each other, and the high frequency voltage is derived from the voltage component of the first frequency ω1 and the first frequency ω1. It is preferable to have at least a component obtained by superimposing a high voltage component of the second frequency ω2.

  A high frequency means what has a frequency of at least 0.5 kHz. The high-frequency voltage is a component obtained by superimposing the voltage component of the first frequency ω1 and the voltage component of the second frequency ω2 higher than the first frequency ω1, and the waveform thereof is on the sine wave of the frequency ω1, The sine wave of ω1 on which the sine wave of higher frequency ω2 is superimposed becomes a waveform that is jagged.

  In the present invention, the discharge start voltage refers to the lowest voltage that can cause a discharge in the discharge space (electrode configuration, etc.) and reaction conditions (gas conditions, etc.) used in the actual thin film formation method. The discharge start voltage varies somewhat depending on the type of gas supplied to the discharge space, the dielectric type of the electrode, etc., but may be considered to be substantially the same as the discharge start voltage of the discharge gas alone.

  By applying a high-frequency voltage as described above between the counter electrodes (discharge space), a discharge capable of forming a thin film can be generated, and high-density plasma necessary for forming a high-quality thin film can be generated. What is important here is that such a high-frequency voltage is preferably applied to each of the opposing electrodes, that is, it is preferably applied from both to the same discharge space.

  Although the superposition of sine waves has been described above, the present invention is not limited to this, and both pulse waves may be used, one may be a sine wave and the other may be a pulse wave. Further, it may have a third voltage component.

  As a specific method of applying the high-frequency voltage of the present invention between the counter electrodes (same discharge space), the first high-frequency voltage having the frequency ω1 and the voltage V1 is applied to the first electrode constituting the counter electrode. It is an atmospheric pressure plasma discharge treatment apparatus in which a first power source to be applied is connected and a second power source to which a second high-frequency voltage having a frequency ω2 and a voltage V2 is applied is connected to a second electrode.

  The atmospheric pressure plasma discharge treatment apparatus includes a gas supply unit that supplies a discharge gas and a thin film forming gas between the counter electrodes. Furthermore, it is preferable to have an electrode temperature control means for controlling the temperature of the electrode.

  Further, it is preferable that a first filter is connected to either the electrode, the first power source or between them, and a second filter is connected to the electrode, the second power source or any of them, the first filter being The frequency current from the first power source is made difficult to pass, the frequency current from the second power source is made easy to pass, and the second filter is vice versa, and the frequency current from the second power source is made to pass. A filter having a function is used for each filter which makes it difficult to pass and easily passes a current having a frequency from the first power source. Here, being difficult to pass means that it preferably passes only 20% or less of the current, more preferably 10% or less. On the contrary, being easy to pass means preferably passing 80% or more of the current, more preferably 90% or more.

  Furthermore, it is preferable that the first power source of the atmospheric pressure plasma discharge processing apparatus of the present invention has a capability of applying a higher frequency voltage than the second power source.

As another discharge condition in the present invention, a high-frequency voltage is applied between the first electrode and the second electrode facing each other, and the high-frequency voltage is applied to the first high-frequency voltage V1 and the second high-frequency voltage V2. When the discharge start voltage is IV,
V1 ≧ IV> V2
Or V1> IV ≧ V2
Meet. More preferably,
V1>IV> V2
Is to satisfy.

  The definition of the high frequency and the discharge start voltage, and the specific method for applying the high frequency voltage of the present invention between the counter electrodes (same discharge space) are the same as those described above.

  Here, the high frequency voltage (applied voltage) and the discharge start voltage in the present invention are those measured by the following method.

(Measurement method of high-frequency voltages V1 and V2 (unit: kV / mm))
A high-frequency probe (P6015A) for each electrode part is installed, and the high-frequency probe is connected to an oscilloscope (Tektronix, TDS3012B) to measure the voltage.

(Measurement method of discharge start voltage IV (unit: kV / mm))
A discharge gas is supplied between the electrodes, the voltage between the electrodes is increased, and a voltage at which discharge starts is defined as a discharge start voltage IV. The measuring instrument is the same as the above high-frequency voltage measurement.

  By adopting a discharge condition that applies a high voltage, even a discharge gas with a high discharge start voltage, such as nitrogen gas, can start a discharge gas and maintain a high density and stable plasma state, forming a high-performance thin film Can be done.

  When the discharge gas is nitrogen gas according to the above measurement, the discharge start voltage IV is about 3.7 kV / mm. Therefore, in the above relationship, the first high-frequency voltage is set as V1 ≧ 3.7 kV / mm. By applying this, nitrogen gas can be excited to be in a plasma state.

  Here, as the frequency of the first power source, a frequency of 200 kHz or less can be preferably used. The electric field waveform may be a sine wave or a pulse. The lower limit is preferably about 1 kHz.

  On the other hand, as the frequency of the second power source, a frequency of 800 kHz or more is preferably used. The higher the frequency of the second power source, the higher the plasma density, and a dense and high-quality thin film can be obtained. The upper limit is preferably about 200 MHz.

  Application of a high-frequency voltage from such two power sources is necessary to start discharge of a discharge gas having a high discharge start voltage on the first frequency ω1 side, and the second frequency ω2 side is plasma. It is necessary to increase the density and form a dense and high-quality thin film.

  In the present invention, the first filter is configured to make it difficult to pass a current having a frequency from the first power source, and to easily pass a current having a frequency from the second power source. The filter is less likely to pass a current having a frequency from the second power source and more likely to pass a current having a frequency from the first power source. In the present invention, any filter having such properties can be used without limitation.

  For example, as the first filter, a capacitor of several tens to several tens of thousands pF or a coil of about several μH can be used according to the frequency of the second power source. As the second filter, a coil of 10 μH or more is used according to the frequency of the first power supply, and it can be used as a filter by grounding through these coils or a capacitor.

  As described above, the atmospheric pressure plasma discharge treatment apparatus of the present invention discharges between the counter electrodes, puts at least the discharge gas and the thin film forming gas introduced between the counter electrodes into a plasma state, and statically discharges between the counter electrodes. A thin film is formed on the substrate by exposing the substrate to be placed or transferred to the plasma state gas. As another method, the atmospheric pressure plasma discharge treatment apparatus discharges between the counter electrodes similar to the above, excites the gas introduced between the counter electrodes or puts it in a plasma state, and excites or jets the gas outside the counter electrode. Even in a jet system in which a gas in a plasma state is blown out and a thin film is formed on the substrate by exposing the substrate in the vicinity of the counter electrode (which may be stationary or transferred) It can be preferably used in the present invention.

  Since a plurality of jet-type atmospheric pressure plasma discharge treatment apparatuses can be connected in series and discharged in the same plasma state at the same time, the gas can be processed many times and processed at high speed. In addition, if each apparatus jets gas in a different plasma state, a laminated thin film having different layers can be formed.

  FIG. 3 is a schematic view showing an example of an atmospheric pressure plasma discharge treatment apparatus of a system that treats a substrate between opposed electrodes, which is particularly useful in the present invention.

  The atmospheric pressure plasma discharge treatment apparatus of the present invention is an apparatus having at least a plasma discharge treatment apparatus 30, a voltage application means 40 having two power supplies, a gas supply means 50, and an electrode temperature adjustment means 60.

  FIG. 3 shows a thin film formed by subjecting the base material F to plasma discharge treatment between the opposed electrodes (discharge space) 32 between the roll rotating electrode (first electrode) 35 and the square tube type fixed electrode group (second electrode) 36. To do.

  In the discharge space (between the counter electrodes) 32 between the roll rotating electrode (first electrode) 35 and the square tube type fixed electrode group (second electrode) 36, the roll rotating electrode (first electrode) 35 has a first power source. The high frequency voltage V1 is applied from 41 to the frequency ω1, and the high frequency voltage V2 is applied to the rectangular fixed electrode group (second electrode) 36 from the second power source 42 at the frequency ω2.

  A first filter 43 is installed between the roll rotation electrode (first electrode) 35 and the first power supply 41 so that the current from the first power supply 41 flows toward the roll rotation electrode (first electrode) 35. The first filter is designed to make it difficult for current from the first power supply 41 to pass through and to easily pass current from the second power supply 42. In addition, a second filter 44 is installed between the square tube type fixed electrode group (second electrode) 36 and the second power source 42 so that the current from the second power source flows toward the second electrode. The second filter 44 is designed to make it difficult for the current from the second power source 42 to pass through and to easily pass the current from the first power source 41.

  In the present invention, the roll rotation electrode 35 may be the second electrode, and the square tube fixed electrode group 36 may be the first electrode. In any case, the first power source is connected to the first electrode, and the second power source is connected to the second electrode. Furthermore, the first power source only needs to have the capability of applying a higher high-frequency voltage (V1> V2) than the second power source. Moreover, the frequency should just have the capability which becomes (omega) 1 <(omega) 2.

  The gas G generated by the gas supply device 51 of the gas supply means 50 is introduced into the plasma discharge processing vessel 31 from the air supply port 52 while controlling the flow rate. The discharge space 32 and the plasma discharge treatment vessel 31 are filled with the gas G.

  The base material F is unwound from the original winding (not shown) and is transported or is transported from the previous process, and the air and the like that is entrained by the base material by the nip roll 65 through the guide roll 64 is blocked. Then, while being wound while being in contact with the roll rotating electrode 35, it is transferred between the square tube fixed electrode group 36 and the roll rotating electrode (first electrode) 35 and the square tube fixed electrode group (second electrode) 36. A voltage is applied from both of them to generate discharge plasma between the counter electrodes (discharge space) 32. The base material F forms a thin film with a gas in a plasma state while being wound while being in contact with the roll rotating electrode 35. The base material F passes through the nip roll 66 and the guide roll 67 and is wound up by a winder (not shown) or transferred to the next process.

  Discharged treated exhaust gas G ′ is discharged from the exhaust port 53. In order to heat or cool the roll rotating electrode (first electrode) 35 and the rectangular tube type fixed electrode group (second electrode) 36 during the formation of the thin film, a medium whose temperature is adjusted by the electrode temperature adjusting means 60 is used as a liquid feed pump. P is sent to both electrodes through the pipe 61, and the temperature is adjusted from the inside of the electrode. Reference numerals 65 and 66 denote partition plates that partition the plasma discharge processing vessel 31 from the outside.

  FIG. 4 is a perspective view showing an example of the structure of the conductive metallic base material of the roll rotating electrode shown in FIG. 3 and the dielectric material coated thereon.

  In FIG. 4, a roll electrode 35a is formed by covering a conductive metallic base material 35A and a dielectric 35B thereon. The inside is a hollow jacket, and the temperature is adjusted.

  FIG. 5 is a perspective view showing an example of the structure of a conductive metallic base material of a rectangular tube electrode and a dielectric material coated thereon.

  In FIG. 5, a rectangular tube type electrode 36a has a coating of a dielectric 36B similar to FIG. 3 on a conductive metallic base material 36A, and the structure of the electrode is a metallic pipe. , It becomes a jacket so that the temperature can be adjusted during discharge.

  In addition, the number of the rectangular tube-shaped fixed electrodes is set in plural along the circumference larger than the circumference of the roll electrode, and the discharge area of the electrodes is a full square tube type facing the roll rotating electrode 35. It is represented by the sum of the area of the fixed electrode surface.

  The rectangular tube electrode 36a shown in FIG. 5 may be a cylindrical electrode, but the rectangular tube electrode has an effect of widening the discharge range (discharge area) as compared with the cylindrical electrode, and thus is preferably used in the present invention. .

  4 and 5, a roll electrode 35a and a rectangular tube electrode 36a are formed by spraying ceramics as dielectrics 35B and 36B on conductive metallic base materials 35A and 36A, respectively, and then sealing the inorganic compound sealing material. Used and sealed. The ceramic dielectric may be a single wall with a thickness of about 1 mm. As the ceramic material used for thermal spraying, alumina, silicon nitride, or the like is preferably used. Among these, alumina is particularly preferable because it is easily processed. Further, the dielectric layer may be a lining-processed dielectric provided with an inorganic material by glass lining.

  Examples of the conductive metal base materials 35A and 36A include titanium metal or titanium alloy, metal such as silver, platinum, stainless steel, aluminum, and iron, a composite material of iron and ceramics, or a composite material of aluminum and ceramics. Although titanium metal or a titanium alloy is particularly preferable for the reasons described later.

  The distance between the two electrodes (electrode gap) is determined in consideration of the thickness of the dielectric provided on the conductive metallic base material, the magnitude of the applied voltage, the purpose of using plasma, etc. The shortest distance between the dielectric surface when a dielectric is provided on one of the electrodes and the surface of the conductive metallic base material, and the distance between the dielectric surfaces when a dielectric is provided on both of the electrodes, In this case, the thickness is preferably from 0.1 to 20 mm, particularly preferably from 0.5 to 2 mm, from the viewpoint of uniform discharge.

  Details of the conductive metallic base material and dielectric useful in the present invention will be described later.

  The plasma discharge treatment vessel 31 is preferably a treatment vessel made of Pyrex (registered trademark) glass or the like, but can be made of metal as long as it can be insulated from the electrodes. For example, polyimide resin or the like may be affixed to the inner surface of an aluminum or stainless steel frame, and the metal frame may be subjected to ceramic spraying for insulation.

As the first power supply (high frequency power supply) installed in the atmospheric pressure plasma discharge treatment apparatus,
Applied power supply symbol Manufacturer Frequency A1 Shinko Electric 3kHz
A2 Shinko Electric 5kHz
A3 Kasuga Electric 15kHz
A4 Shinko Electric 50kHz
A5 HEIDEN Laboratory 100kHz ^*
A6 Pearl Industry 200kHz
And the like, and any of them can be used. The symbol * indicates a HEIDEN Laboratory impulse high-frequency power source (100 kHz in continuous mode).

As the second power source (high frequency power source),
Applied power symbol Manufacturer Frequency B1 Pearl industry 800 kHz
B2 Pearl Industry 2MHz
B3 Pearl Industry 13.56MHz
B4 Pearl Industry 27MHz
B5 Pearl Industry 150MHz
And the like, and any of them can be preferably used.

  In the present invention, it is necessary to employ an electrode capable of maintaining a uniform glow discharge state by applying such a voltage in a plasma discharge processing apparatus.

In the present invention, the power applied between the electrodes facing each other supplies power (output density) of 1 W / cm ² or more to the second electrode, excites the discharge gas to generate plasma, and the energy is formed into a thin film forming gas. To form a thin film. The upper limit value of the power to be supplied is preferably 50 W / cm ² or less, more preferably 20 W / cm ² or less. The lower limit is preferably 1.2 W / cm ² or more. The discharge area (cm ² ) refers to the area in which discharge occurs in the electrode.

  Here, regarding a power supply method, either a continuous sine wave continuous oscillation mode called a continuous mode or an intermittent oscillation mode called ON / OFF intermittently called a pulse mode may be adopted. On the electrode side, a continuous sine wave is preferable because a denser and better quality film can be obtained.

  An electrode used in such a method for forming a thin film by atmospheric pressure plasma must be able to withstand severe conditions in terms of structure and performance. Such an electrode is preferably a metal base material coated with a dielectric.

In the dielectric-coated electrode used in the present invention, it is preferable that the characteristics match between various metallic base materials and dielectrics. One of the characteristics is linear thermal expansion between the metallic base material and the dielectric. The combination is such that the difference in coefficient is 10 × 10 ⁻⁶ / ° C. or less. It is preferably 8 × 10 ⁻⁶ / ° C. or lower, more preferably 5 × 10 ⁻⁶ / ° C. or lower, and further preferably 2 × 10 ⁻⁶ / ° C. or lower. The linear thermal expansion coefficient is a well-known physical property value of a material.

As a combination of a conductive metallic base material and a dielectric whose difference in linear thermal expansion coefficient is within this range,
(1) Metal base material is pure titanium or titanium alloy, dielectric is ceramic sprayed coating (2) Metal base material is pure titanium or titanium alloy, dielectric is glass lining (3) Metal base material is stainless steel Steel, dielectric is ceramic spray coating (4) Metal base is stainless steel, dielectric is glass lining (5) Metal base is composite material of ceramic and iron, and dielectric is ceramic spray coating (6 ) Metallic base material is ceramic and iron composite material, dielectric is glass lining (7) Metallic base material is ceramic and aluminum composite material, dielectric is ceramic sprayed coating (8) Metallic base material is ceramic And a composite material of aluminum and a dielectric such as a glass lining. From the viewpoint of the difference in linear thermal expansion coefficient, the above (1) or (2) and (5) to (8) are preferable, and (1) is particularly preferable.

  In the present invention, titanium or a titanium alloy is particularly useful as the metallic base material from the above characteristics. By using titanium or a titanium alloy as the metal base material, the dielectric is used as described above, so that there is no deterioration of the electrode in use, especially cracking, peeling, dropping off, etc., and it can be used for a long time under harsh conditions. Can withstand.

  The metallic base material of the electrode useful in the present invention is a titanium alloy or titanium metal containing 70% by mass or more of titanium. In the present invention, if the titanium content in the titanium alloy or titanium metal is 70% by mass or more, it can be used without any problem, but preferably contains 80% by mass or more of titanium. As the titanium alloy or titanium metal useful in the present invention, those generally used as industrial pure titanium, corrosion resistant titanium, high strength titanium and the like can be used. Examples of industrial pure titanium include TIA, TIB, TIC, TID, etc., all of which contain very little iron, carbon, nitrogen, oxygen, hydrogen, etc. As content, it has 99 mass% or more. As the corrosion-resistant titanium alloy, T15PB can be preferably used, and it contains lead in addition to the above-described atoms, and the titanium content is 98% by mass or more. Further, as the titanium alloy, T64, T325, T525, TA3, etc. containing aluminum and vanadium or tin other than the above atoms except lead can be preferably used. As a quantity, it contains 85 mass% or more. These titanium alloys or titanium metals have a thermal expansion coefficient that is about 1/2 smaller than that of stainless steel, such as AISI 316, and are combined with a dielectric described later applied on the titanium alloy or titanium metal as a metallic base material. It can withstand the use at high temperature for a long time.

  On the other hand, as a required characteristic of the dielectric, specifically, an inorganic compound having a relative dielectric constant of 6 to 45 is preferable, and examples of such a dielectric include ceramics such as alumina and silicon nitride, Alternatively, there are glass lining materials such as silicate glass and borate glass. In this, what sprayed the ceramics mentioned later and the thing provided by glass lining are preferable. In particular, a dielectric provided by spraying alumina is preferable.

  Alternatively, as one of the specifications that can withstand high power as described above, the porosity of the dielectric is 10% by volume or less, preferably 8% by volume or less, preferably more than 0% by volume and 5% by volume or less. It is. The porosity of the dielectric can be measured by a BET adsorption method or a mercury porosimeter. In the examples described later, the porosity is measured using a dielectric fragment covered with a metallic base material by a mercury porosimeter manufactured by Shimadzu Corporation. High durability is achieved because the dielectric has a low porosity. Examples of the dielectric having such a void and a low void ratio include a high-density, high-adhesion ceramic spray coating by an atmospheric plasma spraying method described later. In order to further reduce the porosity, it is preferable to perform sealing treatment.

  The above-mentioned atmospheric plasma spraying method is a technique in which fine powder such as ceramics, wire, or the like is put into a plasma heat source and sprayed onto a metallic base material to be coated as fine particles in a molten or semi-molten state to form a film. A plasma heat source is a high-temperature plasma gas in which a molecular gas is heated to a high temperature, dissociated into atoms, and further given energy to release electrons. This plasma gas injection speed is high, and since the sprayed material collides with the metallic base material at a higher speed than conventional arc spraying or flame spraying, it is possible to obtain a coating film with high adhesion strength and high density. For details, a thermal spraying method for forming a heat shielding film on a high-temperature exposed member described in JP-A No. 2000-301655 can be referred to. By this method, the porosity of the dielectric (ceramic sprayed film) to be coated can be obtained.

  Another preferable specification that can withstand high power is that the dielectric thickness is 0.5 to 2 mm. The film thickness variation is desirably 5% or less, preferably 3% or less, and more preferably 1% or less.

In order to further reduce the porosity of the dielectric, it is preferable to further perform a sealing treatment with an inorganic compound on the sprayed film such as ceramics as described above. As the inorganic compound, a metal oxide is preferable, and among these, a compound containing silicon oxide (SiO _x ) as a main component is particularly preferable.

  The inorganic compound for sealing treatment is preferably formed by curing by a sol-gel reaction. When the inorganic compound for sealing treatment contains a metal oxide as a main component, a metal alkoxide or the like is applied as a sealing liquid on the ceramic sprayed film and cured by a sol-gel reaction. When the inorganic compound is mainly composed of silica, it is preferable to use alkoxysilane as the sealing liquid.

  Here, it is preferable to use energy treatment for promoting the sol-gel reaction. Examples of the energy treatment include thermal curing (preferably 200 ° C. or less) and ultraviolet irradiation. Furthermore, as a method of sealing treatment, when the sealing liquid is diluted and coating and curing are repeated several times in succession, the mineralization is further improved and a dense electrode without deterioration can be obtained.

In the case of performing a sealing treatment that cures by a sol-gel reaction after coating a ceramic sprayed film using the metal alkoxide or the like of the dielectric-coated electrode according to the present invention as a sealing liquid, the content of the metal oxide after curing is 60 It is preferably at least mol%. When alkoxysilane is used as the metal alkoxide of the sealing liquid, the cured SiO _x (x is 2 or less) content is preferably 60 mol% or more. The content of SiO _x after curing is measured by analyzing a fault of the dielectric layer by XPS.

  In the electrode according to the thin film forming method of the present invention, the maximum height (Rmax) of the surface roughness defined by JIS B 0601 on the side in contact with at least the substrate of the electrode is adjusted to be 10 μm or less. Although it is preferable from the viewpoint of obtaining the effects described in the present invention, the maximum value of the surface roughness is more preferably 8 μm or less, and particularly preferably adjusted to 7 μm or less. In this way, the dielectric surface of the dielectric-coated electrode can be polished to keep the dielectric thickness and the gap between the electrodes constant, the discharge state can be stabilized, and the heat shrinkage difference and residual Distortion and cracking due to stress can be eliminated, and durability can be greatly improved with high accuracy. The polishing finish of the dielectric surface is preferably performed at least on the dielectric in contact with the substrate. Furthermore, the centerline average surface roughness (Ra) defined by JIS B 0601 is preferably 0.5 μm or less, more preferably 0.1 μm or less.

  In the dielectric-coated electrode used in the present invention, another preferred specification that can withstand high power is that the heat-resistant temperature is 100 ° C. or higher. More preferably, it is 120 degreeC or more, Most preferably, it is 150 degreeC or more. The upper limit is 500 ° C. The heat-resistant temperature refers to the highest temperature that can withstand a normal discharge without breakdown. Such heat-resistant temperature can be applied by using the above-mentioned ceramic spraying or dielectric materials provided by layered glass linings with different amounts of bubbles, or within the range of the difference in linear thermal expansion coefficient between the metallic base material and the dielectric material below. This can be achieved by appropriately combining means for appropriately selecting the materials.

[Second electrode]
The second electrode according to the present invention preferably includes at least a conductive fiber. The cathode and anode of the second electrode of the present invention are not particularly limited and can be selected depending on the element configuration. Furthermore, in this invention, a transparent conductive material can be included with a conductive fiber.

〔substrate〕
The substrate is a member that holds the first electrode, the photoelectric conversion layer, and the second electrode that are sequentially stacked. In the present embodiment, a substrate that is transparent to the wavelength of light to be photoelectrically converted so that light that is photoelectrically converted from at least the first electrode or the second electrode, or both electrodes can enter. It is desirable that As the substrate, for example, a glass substrate, a resin substrate and the like are preferably mentioned, but it is desirable to use a transparent resin film from the viewpoint of lightness and flexibility. There is no restriction | limiting in particular in the transparent resin film which can be preferably used as a transparent substrate by this invention, The material, a shape, a structure, thickness, etc. can be suitably selected from well-known things. For example, polyester resins such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN) modified polyester, polyethylene (PE) resin film, polypropylene (PP) resin film, polystyrene resin film, polyolefin resins such as cyclic olefin resin Film, vinyl resin film such as polyvinyl chloride, polyvinylidene chloride, polyether ether ketone (PEEK) resin film, polysulfone (PSF) resin film, polyether sulfone (PES) resin film, polycarbonate (PC) resin film, A polyamide resin film, a polyimide resin film, an acrylic resin film, a triacetyl cellulose (TAC) resin film, and the like can be given. If the resin film transmittance of 80% or more at ~780nm), can be preferably applied to a transparent resin film according to the present invention. Among these, from the viewpoint of transparency, heat resistance, ease of handling, strength and cost, it is preferably a biaxially stretched polyethylene terephthalate film, a biaxially stretched polyethylene naphthalate film, a polyethersulfone film, or a polycarbonate film, and biaxially stretched. A polyethylene terephthalate film and a biaxially stretched polyethylene naphthalate film are more preferable.

  The transparent substrate used in the present invention can be subjected to a surface treatment or an easy-adhesion layer in order to ensure the wettability and adhesion of the coating solution. A conventionally well-known technique can be used about a surface treatment or an easily bonding layer. For example, the surface treatment includes surface activation treatment such as corona discharge treatment, flame treatment, ultraviolet treatment, high frequency treatment, glow discharge treatment, active plasma treatment, and laser treatment. Examples of the easy adhesion layer include polyester, polyamide, polyurethane, vinyl copolymer, butadiene copolymer, acrylic copolymer, vinylidene copolymer, and epoxy copolymer. When the transparent resin film is a biaxially stretched polyethylene terephthalate film, by making the refractive index of the easy adhesion layer adjacent to the film 1.57-1.63, the interface reflection between the film substrate and the easy adhesion layer can be achieved. Since it can reduce and can improve the transmittance | permeability, it is more preferable. The method for adjusting the refractive index can be carried out by appropriately adjusting the ratio of the oxide sol having a relatively high refractive index such as tin oxide sol or cerium oxide sol and the binder resin. The easy adhesion layer may be a single layer, but may be composed of two or more layers in order to improve adhesion. Moreover, the barrier coat layer may be formed in advance on the transparent substrate, or the hard coat layer may be formed in advance on the opposite side to which the transparent conductive layer is transferred.

[Photoelectric conversion layer]
The photoelectric conversion layer 13 is a layer that converts light energy into electric energy, and includes a bulk heterojunction layer in which a p-type semiconductor material and an n-type semiconductor material are uniformly mixed. The p-type semiconductor material functions relatively as an electron donor (donor), and the n-type semiconductor material functions relatively as an electron acceptor (acceptor). Here, the electron donor and the electron acceptor are “an electron donor in which, when light is absorbed, electrons move from the electron donor to the electron acceptor to form a hole-electron pair (charge separation state)”. And an electron acceptor ”, which does not simply donate or accept electrons like an electrode, but donates or accepts electrons by a photoreaction.

  Examples of the p-type semiconductor material used in the present invention include various condensed polycyclic aromatic compounds and conjugated compounds.

  Examples of the condensed polycyclic aromatic compound include anthracene, tetracene, pentacene, hexacene, heptacene, chrysene, picene, fluorene, pyrene, peropyrene, perylene, terylene, quaterylene, coronene, ovalene, thacumanthracene, bisanthene, zeslen, heptazelene. , Pyranthrene, violanthene, isoviolanthene, cacobiphenyl, anthradithiophene, and the like, and derivatives and precursors thereof.

  Examples of the conjugated compound include polythiophene and its oligomer, polypyrrole and its oligomer, polyaniline, polyphenylene and its oligomer, polyphenylene vinylene and its oligomer, polythienylene vinylene and its oligomer, polyacetylene, polydiacetylene, tetrathiafulvalene compound, quinone Compounds, cyano compounds such as tetracyanoquinodimethane, fullerenes and derivatives or mixtures thereof.

  In particular, among polythiophene and oligomers thereof, thiophene hexamer α-seccithiophene α, ω-dihexyl-α-sexualthiophene, α, ω-dihexyl-α-kinkethiophene, α, ω-bis (3- An oligomer such as butoxypropyl) -α-sexithiophene can be preferably used.

  Other examples of the polymer p-type semiconductor include polyacetylene, polyparaphenylene, polypyrrole, polyparaphenylene sulfide, polythiophene, polyphenylene vinylene, polycarbazole, polyisothianaphthene, polyheptadiyne, polyquinoline, polyaniline, and the like. Japanese Laid-Open Patent Publication No. 2006-36755 and other substituted-unsubstituted alternating copolymer polythiophenes, Japanese Patent Laid-Open No. 2007-51289, Japanese Patent Laid-Open No. 2005-76030, J. Pat. Amer. Chem. Soc. , 2007, p4112, J.A. Amer. Chem. Soc. , 2007, p7246, etc., polymers having a condensed ring thiophene structure, WO2008 / 000664, Adv. Mater. , 2007, p4160, Macromolecules, 2007, Vol. Examples thereof include thiophene copolymers such as 40 and p1981.

  Furthermore, porphyrin, copper phthalocyanine, tetrathiafulvalene (TTF) -tetracyanoquinodimethane (TCNQ) complex, bisethylenetetrathiafulvalene (BEDTTTTF) -perchloric acid complex, BEDTTTF-iodine complex, TCNQ-iodine complex, etc. Organic molecular complexes, fullerenes such as C60, C70, C76, C78 and C84, carbon nanotubes such as SWNT, dyes such as merocyanine dyes and hemicyanine dyes, σ-conjugated polymers such as polysilane and polygerman, and Organic-inorganic hybrid materials described in 2000-260999 can also be used.

  Among these π-conjugated materials, at least one selected from the group consisting of condensed polycyclic aromatic compounds such as pentacene, fullerenes, condensed ring tetracarboxylic acid diimides, metal phthalocyanines, and metal porphyrins is preferable. Further, pentacenes are more preferable.

  Examples of pentacenes include substituents described in International Publication No. 03/16599, International Publication No. 03/28125, US Pat. No. 6,690,029, Japanese Patent Application Laid-Open No. 2004-107216, and the like. A pentacene derivative described in U.S. Patent Application Publication No. 2003/136964 and the like; Amer. Chem. Soc. , Vol127. Examples thereof include substituted acenes described in No. 14.4986 and the like and derivatives thereof.

  Among these compounds, compounds that have high solubility in organic solvents to the extent that solution processing is possible, can form a crystalline thin film after drying, and can achieve high mobility are preferable. Such compounds include those described in J. Org. Amer. Chem. Soc. , Vol. 123, p9482; Amer. Chem. Soc. , Vol. 130 (2008), no. No. 9, 2706 and the like, acene-based compounds substituted with a trialkylsilylethynyl group, a pentacene precursor described in U.S. Patent Application Publication No. 2003/136964, etc., and Japanese Patent Application Laid-Open No. 2007-224019 Examples include precursor type compounds (precursors) such as porphyrin precursors. Among these, the latter precursor type can be preferably used. This is because the precursor type is insolubilized after conversion, so when forming the hole transport layer, electron transport layer, hole block layer, electron block layer, etc. on the bulk heterojunction layer by a solution process, Since the bulk heterojunction layer will not be dissolved, the material constituting the layer and the material forming the bulk heterojunction layer will not be mixed, thereby further improving the efficiency and life. Because it can.

  As a p-type semiconductor material of the organic photoelectric conversion element of the present invention, a chemical structure change is caused by a method such as exposing a precursor of a p-type semiconductor material to a vapor of a compound that causes heat, light, radiation, or a chemical reaction. A compound converted into a semiconductor material is preferred. Among them, compounds that cause a scientific structural change by heat are preferred.

  Examples of n-type semiconductor materials include fullerene, octaazaporphyrin, p-type semiconductor perfluoro compounds (perfluoropentacene, perfluorophthalocyanine, etc.), naphthalenetetracarboxylic anhydride, naphthalenetetracarboxylic diimide, perylenetetracarboxylic acid Examples thereof include polymer compounds containing an anhydride, an aromatic carboxylic acid anhydride such as perylenetetracarboxylic acid diimide, or an imidized product thereof as a skeleton.

  Among these, fullerene-containing polymer compounds are preferable. Fullerene-containing polymer compounds include fullerene C60, fullerene C70, fullerene C76, fullerene C78, fullerene C84, fullerene C240, fullerene C540, mixed fullerene, fullerene nanotubes, multi-walled nanotubes, single-walled nanotubes, nanohorns (conical), etc. Examples thereof include a polymer compound having a skeleton. As the fullerene-containing polymer compound, a polymer compound (derivative) having fullerene C60 as a skeleton is preferable.

  The fullerene-containing polymers are roughly classified into polymers in which fullerene is pendant from a polymer main chain and polymers in which fullerene is contained in the polymer main chain. Fullerene is contained in the polymer main chain. Are preferred. This is not because fullerene is contained in the main chain because the polymer does not have a branched structure, so that it can be packed with high density when solidified, resulting in high mobility. It is estimated that.

  Examples of a method for forming a bulk heterojunction layer in which an electron acceptor and an electron donor are mixed include a vapor deposition method and a coating method (including a casting method and a spin coating method). Among these, a coating method is particularly preferable.

  Then, the bulk heterojunction layer of the photoelectric conversion part is annealed at a predetermined temperature during the manufacturing process in order to improve the photoelectric conversion rate, and is partially crystallized microscopically.

  In the photoelectric conversion element, light incident from the transparent electrode through the substrate is absorbed by the electron acceptor or electron donor in the bulk heterojunction layer of the photoelectric conversion unit, and electrons move from the electron donor to the electron acceptor. A pair of holes and electrons (charge separation state) is formed. The generated charge is caused by an internal electric field, for example, when the work function of the transparent electrode and the counter electrode is different, due to the potential difference between the transparent electrode and the counter electrode, electrons pass between the electron acceptors and holes are electron donors. The photocurrent is detected by passing through different electrodes to different electrodes. For example, when the work function of the transparent electrode is larger than that of the counter electrode, electrons are transported to the transparent electrode and holes are transported to the counter electrode. If the magnitude of the work function is reversed, electrons and holes are transported in the opposite direction. In addition, the transport direction of electrons and holes can be controlled by applying a potential between the transparent electrode and the counter electrode.

  The photoelectric conversion unit may be composed of a single layer in which an electron acceptor and an electron donor are uniformly mixed, or may be composed of a plurality of layers in which the mixing ratio of the electron acceptor and the electron donor is changed. Good.

  Examples of a method for forming a bulk heterojunction layer in which an electron acceptor and an electron donor are mixed include a vapor deposition method and a coating method (including a casting method and a spin coating method). Among these, the coating method is preferable in order to increase the area of the interface where charges and electrons are separated from each other as described above and to produce a device having high photoelectric conversion efficiency. After application, it is preferable to perform heating in order to cause removal of residual solvent, moisture and gas, and chemical reaction of the semiconductor material as described above.

[Middle layer]
Further, the above-described bulk heterojunction type organic photoelectric conversion element is composed of a transparent electrode, a photoelectric conversion part of a bulk heterojunction layer, and a counter electrode that are sequentially stacked on a substrate. A bulk heterojunction type organic photoelectric conversion element having another layer such as a hole transport layer, an electron transport layer, a hole block layer, an electron block layer, or a smoothing layer between the counter electrode and the photoelectric conversion unit It may be configured. Among these, a hole transport layer or an electron blocking layer is placed between the bulk heterojunction layer and the anode (usually the transparent electrode side), and an electron transport layer or electron blocking layer is placed between the cathode (usually the counter electrode side). By forming the hole blocking layer, charges generated in the bulk heterojunction layer can be taken out more efficiently. Therefore, these layers are preferably included.

[Tandem configuration]
For the purpose of improving the sunlight utilization rate (photoelectric conversion efficiency), a tandem configuration in which photoelectric conversion elements are stacked may be employed. In the case of a tandem type configuration, after laminating a transparent electrode and a first photoelectric conversion part on a substrate in sequence, a charge recombination layer is laminated, and then a second photoelectric conversion part and then a counter electrode are laminated, A tandem configuration can be adopted. The second photoelectric conversion unit may be a layer that absorbs the same spectrum as the absorption spectrum of the first photoelectric conversion unit, or may be a layer that absorbs a different spectrum, but is preferably a layer that absorbs a different spectrum. The material of the charge recombination layer is preferably a layer using a compound having both transparency and conductivity, such as transparent metal oxides such as ITO, AZO, FTO, and titanium oxide, Ag, Al, Au, etc. A very thin metal layer, a conductive polymer material such as PEDOT: PSS, polyaniline, and the like are preferable.

[Sealing]
Moreover, it is preferable to seal by the well-known method so that the produced organic photoelectric conversion element may not deteriorate with oxygen, moisture, etc. in the environment. For example, a method of sealing a cap made of aluminum or glass by bonding with an adhesive, a plastic film on which a gas barrier layer such as aluminum, silicon oxide, or aluminum oxide is formed and the organic photoelectric conversion element top 10 with an adhesive A method of bonding, a method of spin-coating an organic polymer material with high gas barrier properties (polyvinyl alcohol, etc.), a method of directly depositing an inorganic thin film with high gas barrier properties (silicon oxide, aluminum oxide, etc.), and a combination of these The method of laminating can be mentioned.

(Preparation of organic photoelectric conversion element SC-101)
《Metal nanowires》
A PEN film substrate with a barrier layer on which an indium tin oxide (ITO) transparent conductive film is deposited to a thickness of 150 nm (sheet resistance 13Ω / □) is 10 × 100 mm square using normal photolithography technology and hydrochloric acid etching. The first light-receiving part and the extraction electrode part were patterned to form a first electrode.

  The patterned first electrode was washed in the order of ultrasonic cleaning with a surfactant and ultrapure water, followed by ultrasonic cleaning with ultrapure water, dried with nitrogen blow, and finally subjected to ultraviolet ozone cleaning.

In this example, silver nanowires were used as metal nanowires. Silver nanowires are described in Adv. Mater. , 2002, 14, 833 to 837, silver nanowires having an average diameter of 75 nm and an average length of 35 μm were prepared, and the silver nanowires were filtered and washed with an ultrafiltration membrane, followed by ethanol. It was re-dispersed in a silver nanowire (AgNW) dispersion (silver nanowire content 5 mass%). On the PEN film substrate on which ITO was deposited, the silver nanowire dispersion liquid was applied using an applicator so that the amount of silver nanowires was 80 mg / m ² and dried to form a silver nanowire network structure.

  Furthermore, after performing electrolytic copper plating treatment at 25 ° C. using the following electrolytic plating solution, washing with water and drying treatment were performed. In addition, the current control in electrolytic copper plating was performed over 3 minutes, 3 minutes for 1 minute and then 12 minutes for 1A.

  After the completion of the plating treatment, the plate was washed with pure water for 10 minutes to carry out a water washing treatment, and dried using a drying air (50 ° C.) until it was in a dry state.

(Electrolytic plating solution)
Copper sulfate (pentahydrate) 200g
50g of sulfuric acid
Sodium chloride 0.1g
Add water to bring the total volume to 1000 ml.

  Irradiation was performed under the following plasma treatment conditions, and the plating electrode surface was oxidized to produce the first electrode of the present invention having a metal oxide coating on the surface.

(Plasma treatment conditions)
Carrier gas: Nitrogen Reactive gas: Oxygen (12% by volume with respect to nitrogen)
First power supply: HEIDEN lab PHF-6k (100kHz)
Second power supply: Pearl Industrial CF-5000-13M (13.56 MHz)
Applied output: 1.0 W / cm ²
Electrode temperature control: 80 ° C
Processing time: 2 seconds From then on, the substrate was brought into the glove box and operated in a nitrogen atmosphere.

Next, P3HT (manufactured by Plextronics: regioregular poly-3-hexylthiophene) (Mw = 52000, high molecular p-type semiconductor material) and PCBM (frontier carbon: 6,6-phenyl-C ₆₁ -butylic) were added to chlorobenzene. (Acid methyl ester) (Mw = 911, low molecular weight n-type semiconductor material) prepared in a ratio of 1: 1 to 3.0% by mass, applied to a film thickness of 300 nm while filtering through a filter. And allowed to stand at room temperature to form a photoelectric conversion layer.

  Next, a solution in which Ti-isopropoxide is dissolved in ethanol so as to have a concentration of 0.05 mol / L is prepared, masked, and then applied to a film thickness of 20 nm, and left in the atmosphere with a controlled amount of water vapor. Then, an electron transport layer was formed.

Next, the fabricated element is placed in a vacuum deposition apparatus, a shadow mask with a width of 1 cm is set, the inside of the vacuum deposition apparatus is decompressed to 1 × 10 ⁻³ Pa or less, and the film thickness of aluminum becomes 100 nm. Thus, the second electrode was formed.

  The obtained organic photoelectric conversion element SC-101 was sealed using a PEN film with a barrier and a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) in a nitrogen atmosphere.

(Preparation of organic photoelectric conversion element SC-102)
In the production of the organic photoelectric conversion element SC-101, the organic photoelectric conversion element is changed except that the metal to be plated is changed to nickel, nickel is oxidized as described above, and the nickel oxide-coated silver nanowire is used as the first electrode. Organic photoelectric conversion element SC-102 was obtained in the same manner as SC-101.

  The obtained organic photoelectric conversion element SC-102 was sealed using a PEN film with a barrier and a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) in a nitrogen atmosphere.

(Preparation of organic photoelectric conversion element SC-103)
In the production of the organic photoelectric conversion element SC-101, after changing the conductive fiber to a dispersion of SWCNT (manufactured by Unidym, HiPcoR single-walled carbon nanotubes) and adjusting the basis weight of SWCNT to 10 mg / m ² The organic photoelectric conversion element SC-103 is the same as the organic photoelectric conversion element SC-101 except that nickel is plated and nickel is oxidized as described above, and the nickel oxide-coated silver nanowire is used as the first electrode. Got.

  The obtained organic photoelectric conversion element SC-103 was sealed using a PEN film with a barrier and a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) in a nitrogen atmosphere.

(Preparation of organic photoelectric conversion element SC-104)
In the production of the organic photoelectric conversion element SC-101, the metal to be plated was changed to nickel, and the nickel was oxidized by heating at 300 ° C. for 10 minutes in the atmosphere. The nickel oxide-coated silver nanowire was used as the first electrode. Except for the above, an organic photoelectric conversion element SC-104 was obtained in the same manner as the organic photoelectric conversion element SC-101.

  The obtained organic photoelectric conversion element SC-104 was sealed using a PEN film with a barrier and a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) in a nitrogen atmosphere.

(Preparation of organic photoelectric conversion element SC-105)
In the production of the organic photoelectric conversion element SC-101, the organic photoelectric conversion element SC was made in the same manner as the organic photoelectric conversion element SC-101 except that the surface of the silver nanowire was coated with nickel oxide by a laser beam evaporation method to form the first electrode. -105 was obtained.

  The obtained organic photoelectric conversion element SC-105 was sealed using a PEN film with a barrier and a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) in a nitrogen atmosphere.

(Preparation of organic photoelectric conversion element SC-106)
In the production of the organic photoelectric conversion element SC-101, Baytron P4083 (manufactured by HC Starck Co., Ltd.) was applied on the silver nanowires and dried to obtain the first electrode, which was the same as the organic photoelectric conversion element SC-101. Thus, an organic photoelectric conversion element SC-106 was obtained.

  The obtained organic photoelectric conversion element SC-106 was sealed using a PEN film with a barrier and a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) in a nitrogen atmosphere.

(Preparation of organic photoelectric conversion element SC-107)
In the production of the organic photoelectric conversion element SC-101, the metal to be plated was changed to zinc, the zinc was oxidized as described above, and the zinc oxide-coated silver nanowire was used as the first electrode. After this, the substrate was brought into the glove box and worked under a nitrogen atmosphere.

Next, P3HT (manufactured by Plextronics: regioregular poly-3-hexylthiophene) (Mw = 52000, high molecular p-type semiconductor material) and PCBM (frontier carbon: 6,6-phenyl-C ₆₁ -butylic) were added to chlorobenzene. (Acid methyl ester) (Mw = 911, low molecular weight n-type semiconductor material) prepared in a ratio of 1: 1 to 3.0% by mass, applied to a film thickness of 300 nm while filtering through a filter. And allowed to stand at room temperature to form a photoelectric conversion layer.

  Next, Baytron P4083 (manufactured by HC Starck Co., Ltd.), which is an electropolymer, was applied to a film thickness of 50 nm and then dried to form a hole transport layer.

Next, the fabricated element is placed in a vacuum deposition apparatus, a 1 cm wide shadow mask is set, the inside of the vacuum deposition apparatus is depressurized to 1 × 10 ⁻³ Pa or less, and the film thickness of gold becomes 100 nm. Thus, the second electrode was formed.

  The obtained organic photoelectric conversion element SC-107 was sealed using a PEN film with a barrier and a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) in a nitrogen atmosphere.

(Preparation of organic photoelectric conversion element SC-108)
In the production of the organic photoelectric conversion element SC-107, the organic photoelectric conversion element was changed except that the metal to be plated was changed to titanium, the titanium was oxidized as described above, and the titanium oxide-coated silver nanowire was used as the first electrode. Organic photoelectric conversion element SC-108 was obtained in the same manner as SC-106.

  The obtained organic photoelectric conversion element SC-108 was sealed using a PEN film with a barrier and a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) in a nitrogen atmosphere.

(Preparation of organic photoelectric conversion element SC-109)
In the production of the organic photoelectric conversion element SC-107, a solution in which Ti-isopropoxide was dissolved in ethanol to 0.05 mol / L was prepared, masked, and then deposited on the silver nanowire so as to have a film thickness of 20 nm. An organic photoelectric conversion element SC-109 was obtained in the same manner as the organic photoelectric conversion element SC-106, except that it was coated and left in the atmosphere where the amount of water vapor was adjusted to form the first electrode.

  The obtained organic photoelectric conversion element SC-109 was sealed using a PEN film with a barrier and a UV curable resin (manufactured by Nagase ChemteX Corporation, UV RESIN XNR5570-B1) in a nitrogen atmosphere.

[Evaluation of conversion efficiency]
A 1 cm square mask is used for the organic photoelectric conversion element that has been sealed as described above, and the solar simulator (AM1.5G filter) is irradiated with light having an intensity of 100 mW / cm ² from the first electrode side. -V characteristics were measured, and short circuit current density Jsc (mA / cm ² ), open circuit voltage Voc (V), and fill factor FF were measured. Further, energy conversion efficiency η (%) was obtained from Jsc, Voc, and FF according to Equation 1.

Formula 1 Jsc (mA / cm ² ) × Voc (V) × FF = η (%)
[Evaluation of coverage]
The coverage of the metal oxide on the surface of the metal nanowire was obtained from the detected amount (atomic%) of Ag obtained from an XPS (X ship photoelectron spectroscopy) spectrum.

  As is apparent from Table 1, it can be seen that the organic photoelectric conversion element of the present invention has an excellent effect in energy conversion efficiency.

F base material G reactive gas G ′ exhaust gas 11 substrate 12 first electrode (anode electrode)
13 Photoelectric conversion layer 14 Second electrode (transparent cathode electrode)
DESCRIPTION OF SYMBOLS 21 Substrate 22 1st electrode 23 Hole transport layer 24 Bulk heterojunction type photoelectric conversion layer 25 Electron transport layer 26 Second electrode 31 Plasma discharge treatment vessel 35 Roll rotating electrode 36 Square tube type fixed electrode group 40 Voltage application means 51 Gas supply device 52 Gas supply port 53 Gas exhaust port 60 Electrode temperature adjusting means 64, 67 Guide roll 65, 66 Nip roll 68, 69 Partition plate

Claims (12)

  In the method for producing an organic photoelectric conversion element having a bulk heterojunction photoelectric conversion layer sandwiched between a first electrode and a second electrode, and a hole transport layer or an electron transport layer, the first electrode is a metal A And the step of forming the hole transport layer or the electron transport layer comprises a step of coating a material containing a metal B different from the metal A or a metal B on the first electrode, A process for oxidizing the metal B, and a method for producing an organic photoelectric conversion element.   The method for producing an organic photoelectric conversion element according to claim 1, wherein the metal B is supplied from a metal salt compound containing the metal B.   3. The step of coating the substance containing the metal B or the metal B includes the step of oxidizing the metal B after forming the first electrode made of the metal A. The manufacturing method of the organic photoelectric conversion element of description.   The method for manufacturing an organic photoelectric conversion element according to any one of claims 1 to 3, wherein the step of coating the metal B uses a plating method.   The method for producing an organic photoelectric conversion element according to claim 1, wherein the step of oxidizing the substance containing the metal B uses atmospheric pressure plasma.   The layer between at least one of the first electrode and the second electrode and the bulk heterojunction layer is at least one of a hole transport layer and an electron transport layer. The manufacturing method of the organic photoelectric conversion element of Claim 1.   The said metal B contains at least any one of Ti, Ni, Cu, and Zn, The manufacturing method of the organic photoelectric conversion element of any one of Claims 1-6 characterized by the above-mentioned.   The method for producing an organic photoelectric conversion element according to claim 1, wherein the surface of the first electrode has irregularities.   The method for producing an organic photoelectric conversion element according to any one of claims 1 to 8, wherein the metal A forming the first electrode includes at least one of a conductive fiber and a nanorod.   The method for producing an organic photoelectric conversion element according to claim 9, wherein the conductive fiber includes at least one of a metal nanowire and a carbon nanotube.   The method for producing an organic photoelectric conversion element according to claim 10, wherein the metal nanowire is a silver nanowire.   The organic photoelectric conversion element manufactured by the manufacturing method of the organic photoelectric conversion element of any one of Claims 1-11.

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