JP4465282B2 - Organic device and manufacturing method thereof - Google Patents

Description

  The present invention relates to an organic device using an organic compound. More specifically, the present invention relates to an organic device having an organic layer composed of a plurality of π-conjugated molecular layers directly connected by covalent bonds. The organic device of the present invention can be suitably used for photoelectric conversion elements such as organic solar cells, electroluminescent elements such as organic EL elements, and the like.

  In recent years, organic devices have been actively studied for application to solar cells, EL elements, and thin film transistors because of the cost reduction, flexibility, and large area. However, many problems still remain, and one of them is the low carrier mobility of organic layers made of organic molecules. There are two main reasons for the low mobility.

  One of them is a method of forming an organic layer. At present, a general method for forming an organic layer is a vacuum deposition method for a low molecular material, and a spin coating method or an ink jet method for a high molecular material. In these methods, organic molecules having anisotropy are orientated randomly in the organic layer. For this reason, it is difficult to improve the mobility by utilizing the anisotropy.

  The other is in the conduction mechanism of carriers in the organic layer. In the low molecular organic semiconductor layer, it is considered that carriers propagate by hopping or tunneling between organic molecules. Further, even in the polymer organic semiconductor layer, a part of the molecule (molecular chain) can be used as a conductive path. However, like the low molecular organic semiconductor layer, the carrier conduction mechanism is considered to be hopping or tunneling in the entire layer.

  Therefore, in order to obtain an organic device with high mobility, the organic molecules are arranged in one direction (alignment of the organic molecules anisotropy), and the device configuration is such that carriers are transported in the arrangement direction. It is necessary to design organic molecules so that the molecular chain is responsible for carrier propagation.

  In Japanese Patent Application Laid-Open No. 11-265789 (Patent Document 1), a molecule having a hole transport property, a light emission property, and an electron transport property is arranged on a gold electrode by a Langmuir-Blodget method. An organic EL element having a layer and a counter electrode formed thereon is disclosed. That is, in this publication, it is considered to provide an organic EL element with high luminous efficiency by arranging organic molecules and improving the carrier transport efficiency in the aligned molecular chain direction.

JP-A-11-265786

  However, the above publication has a problem that high luminous efficiency cannot be expected. More specifically, in the above publication, the molecule forming the organic layer includes a plurality of sites having hole transport properties, light emission properties, and electron transport properties in a single molecule, so that the molecular chain is inevitably long. Then, although there are normal molecules that are aligned and fixed perpendicular to the electrodes, some molecules are aligned in parallel. Since the direction of this molecule is different from the carrier transport direction (perpendicular to the electrode), carrier transport is hindered. Therefore, this molecule does not fulfill the function of light emission and causes a decrease in light emission efficiency.

  The above-mentioned problem is not limited to the organic EL element, and the same problem can be considered from the viewpoint that carrier transport is hindered even in an organic solar battery. Therefore, the provision of an organic solar cell having an organic layer that can realize higher photoelectric conversion efficiency is also desired.

Thus, according to the present invention, the first electrode layer, the organic layer, and the second electrode layer are provided in this order, and the organic layer includes a plurality of π-conjugated molecular layers and is in contact with the first electrode layer. The molecular layer is covalently bonded to the first electrode layer and oriented in a direction substantially perpendicular to the surface of the first electrode layer, and the adjacent π-conjugated molecular layers are covalently bonded to each other, and the π-conjugated molecular layer Is composed of π-conjugated molecules having a linear structure, and the organic layer has a laminated structure in which π-conjugated molecular layers derived from aromatic compounds and π-conjugated molecular layers derived from acetylene are alternately covalently bonded. An organic device is provided.

Furthermore, according to the present invention, on the first electrode layer, the first π-conjugated molecular layer is oriented in a direction substantially perpendicular to the surface of the first electrode layer while covalently bonding to the first electrode layer. And a second step of laminating the second and subsequent π-conjugated molecular layers on the first π-conjugated molecular layer while covalently bonding to an adjacent π-conjugated molecular layer. And a third step of forming a second electrode layer on the organic layer composed of a plurality of π-conjugated molecular layers obtained in the first and second steps, and the π-conjugated molecular layer has a linear structure consists π-conjugated molecules with the organic layer, wherein Rukoto that the aromatics π-conjugated molecular layer derived from the product and π-conjugated molecular layer derived from the acetylene having a covalently bonded laminated structure alternately An organic device manufacturing method is provided.

According to the organic device and the manufacturing method thereof of the present invention, molecules that do not contribute to carrier transport can be reduced as much as possible.
Since the conventional manufacturing method uses a long molecular chain, there is a possibility that molecules are arranged in parallel to the substrate. That is, there were many molecules that did not contribute to carrier transport.

  However, in the present invention, the organic layer is divided into a plurality of molecular layers, and the molecular chains constituting the molecular layer are shortened, thereby contributing to the transport of molecules that are arranged in parallel to the substrate, so-called carriers. It is possible to reduce as many molecules as possible.

  In addition, the organic device of the present invention inevitably includes an organic layer composed of a plurality of π-conjugated molecular layers, and has a structure in which π-conjugated molecules arranged in the same direction as the carrier transport direction are increased. Since these π-conjugated molecular layers are covalently bonded to each other, the π-conjugate is extended, and the molecular chain can be used as a conductive path. As a result, carrier transport efficiency is increased. Therefore, since the site | part which does not fulfill | perform light emission and a photoelectric conversion function reduces, if it is an organic EL element, it will become possible to improve luminous efficiency, and if it is an organic solar cell, it will become possible to improve conversion efficiency.

  In addition, since the π-conjugated molecular layer is composed of π-conjugated molecules having a linear structure (one-dimensional structure), the orientation can be further improved, so that the carrier mobility can be further improved.

  In addition, since the π-conjugated molecular layer is composed of π-conjugated molecules having a highly planar structure in the main chain direction, the effective conjugated chain length can be extended and the molecular chain can be used as a carrier transfer path. Mobility can be further improved.

  Further, the π-conjugated molecular layer in contact with the first electrode layer is a π-conjugated molecular layer oriented in a direction substantially perpendicular to the surface of the first electrode layer, so that carrier injection between the first electrode layer and the organic layer, or The extraction efficiency can be improved.

  Further, when the organic layer includes at least one π-conjugated molecular layer made of a molecule containing a heterocyclic ring, a function specific to a hetero atom can be imparted.

  In addition, since the organic layer includes the p-type and n-type π-conjugated molecular layers, excitons generated at the interface between the two layers can be efficiently transported to the electrode, so that an organic solar cell with high photoelectric conversion efficiency can be provided. .

  In addition, the organic layer includes a hole-transporting π-conjugated molecular layer, a light-emitting π-conjugated molecular layer, and an electron-transporting π-conjugated molecular layer, so that carriers can be transported to the light-emitting layer using the molecular chain as a conductive path. Since the efficiency can be improved, an organic EL element with high light emission efficiency and low driving voltage can be provided.

  Alternatively, a π-conjugated molecular layer derived from an aromatic compound and a π-conjugated molecular layer derived from acetylene may have a laminated structure in which covalent bonds are alternately bonded. In this case, since the π-conjugated molecules constituting the organic layer can be linearly arranged with respect to the surface of the first electrode layer, the orientation of the organic layer can be increased, and the π-conjugated molecules aligned in parallel with the surface of the first electrode layer have a planar structure. Therefore, the effective conjugated chain length of the organic layer can be increased. Therefore, carrier mobility can be increased.

  In addition, the π-conjugated molecular layer in the second step is derived from a π-conjugated molecule having two functional groups at positions separated from each other, and multiple π-conjugated molecular layers are formed by repeating condensation reactions of functional groups adjacent in the stacking direction. You may laminate. In this case, since the π-conjugated molecular layer can be stacked in a substantially vertical direction, it is possible to control the molecular chain length of the compound composed of π-conjugated molecules, that is, the thickness of the organic layer.

  In addition, the π-conjugated molecule having the two functionalities is a molecule in which one functional group is protected, and the π-conjugated molecular layer in the second step is used as the other functional group of the protected compound as π. You may include the process laminated | stacked by repeating the process laminated | stacked by making it condense with the functional group of a conjugated molecular layer, and the process deprotecting the protected molecule | numerator. In this case, a single molecule may be prepared and repeatedly stacked, so that the cost of device fabrication can be reduced.

  The covalent bond may be formed by cross coupling of aryl halide and ethynyl aryl, or cross coupling of aryl boron compound and aryl halide. In the former case, an organic layer composed of a π-conjugated compound having an arylene ethynylene skeleton can be obtained in a high yield under mild conditions. In the latter case, an organic layer composed of a polycyclic π-conjugated compound can be obtained in a high yield.

The structure, material, and manufacturing method of the organic device of the present invention will be described with reference to FIGS.
First, the structure will be described.
1a) and b) schematically depict the basic structure of the present invention. A substrate 11, a first electrode layer 12, a plurality of π-conjugated molecular layers 13, and a second electrode layer 14 are configured. 1a) and b), n and m indicate the number of π-conjugated molecular layers, and the π-conjugated molecular layer refers to a unit of a layer in which a single π-conjugated molecule is laminated. Therefore, the plurality of π-conjugated molecular layers may be the same molecular layer laminated a plurality of times (FIG. 1a)) or various molecular layers laminated a plurality of times (FIG. 1b)).

  In addition, as a result of the molecular layer being laminated a plurality of times, the organic layer formed is covalently bonded to the first electrode layer, and organic molecules (π-conjugated molecules) 15 arranged in a direction substantially perpendicular to the surface of the first electrode layer. It is composed of aggregates. According to such a structure, a π-conjugated molecular chain formed as a result of arranging π-conjugated molecules in the same direction as the carrier transport direction can be used as a conductive path of carriers. Therefore, the carrier transport efficiency is increased, and if it is an organic EL element, the luminous efficiency can be improved, and if it is an organic solar cell, the conversion efficiency can be improved. In particular, by providing a plurality of π-conjugated molecular layers, the arrangement of molecules can be controlled, and the number of molecules arranged in parallel to the electrode surface can be reduced as much as possible. Here, “substantially perpendicular” means a range of 45 to 90 ° with respect to the surface of the first electrode.

  In addition, when the molecular chain of the π-conjugated molecular layer is long to some extent (such as those that include hole transport properties, light emission properties, and electron transport properties in a single molecule), there is a risk that the molecules will be aligned parallel to the electrode surface. is there. Since the light emission and photoelectric conversion functions cannot be obtained at the portions arranged in parallel, the light emission and photoelectric conversion efficiency decreases. That is, the problem can be solved by shortening the molecular chain of one π-conjugated molecular layer as in the present invention.

Next, materials will be described.
The material that can be used for the substrate 11 is preferably a transparent material in consideration of application to a photoelectric conversion device or an electroluminescent device. Specifically, glass, quartz, an acrylic resin, etc. are mentioned. Note that the substrate is not essential and may also be used as the first electrode layer.

  The material that can be used for the first electrode layer 12 is preferably an inorganic oxide or a metal on which a thin natural oxide film is easily formed. The latter is preferably a metal that generates a hydroxyl group on the surface by oxygen plasma treatment or acid treatment. Specific examples include inorganic oxides such as ITO (indium tin oxide) and IZO (indium zinc oxide), metals such as doped silicon and aluminum.

Next, materials that can be used for the plurality of π-conjugated molecular layers forming the organic layer will be described.
The π-conjugated molecules used to form a plurality of π-conjugated molecular layers can be stacked with higher yield as the molecular size is smaller. Examples of the π-conjugated molecule include aromatic hydrocarbons having 6 to 12 carbon atoms, heterocyclic compounds having 4 to 8 carbon atoms, unsaturated aliphatic hydrocarbons having 2 to 4 carbon atoms, and combinations of these compounds. It is done.

  For example, aromatic hydrocarbons such as benzene, biphenyl, phenylacetylene, styrene, fluorene, diethynylbenzene, and diethenylbenzene as shown in FIG. 2a) are preferable.

  Moreover, heterocyclic compounds such as thiophene, pyrrole, and their polycyclic compounds as shown in FIG. 2b), and compounds having acetylene or ethylene added thereto are preferred. If these compounds are used, the planarity is high and high carrier mobility can be obtained in the molecular chain direction. Pyridine or silole, polycyclic compounds thereof, and compounds to which acetylene or ethylene is added may be used as molecular layer units. In the case of pyridine, the electronegativity of nitrogen is large, and in the case of silole, the σ * -π * conjugation between the σ * orbital of the silicon site and the π * orbital of the diene site (S. Yamaguchi and K. Tamao Bull. Chem. Soc. Jpn. 1996, 69, 2327.), LUMO can be reduced. As a result, an electron transport layer in which the characteristics of the n-type molecular layer are expressed can be formed. In other words, at least one layer of the π-conjugated molecular layer is formed from a molecular layer containing a heterocyclic ring, so that an effect unique to the hetero atom can be imparted to the organic layer. In FIG. 2b), X means N, S, O, Si or the like.

  In particular, organic layers in which 6-membered aromatic compounds such as benzene and pyridine and linear hydrocarbons such as acetylene and ethylene are alternately laminated, and organic layers in which thiophene and pyrrole are bonded in a polycyclic manner This is preferable because the twist of the chain is small and the planarity of the conjugate plane is high. Since these organic layers can extend the effective conjugated chain length, the carrier mobility using the molecular chain as a conductive path can be further improved. High planarity means that the dihedral angle (twist) between 6- or 5-membered rings in a chain composed of a series of π-conjugated molecules constituting the organic layer is small. In the present invention, the dihedral angle is preferably 30 ° or less.

Next, the functional group covalently bonded to each layer will be described.
First, the bond of the first π-covalent molecular layer on the first electrode layer 12 is not particularly limited as long as it is derived from a functional group that can be covalently bonded to the first electrode layer. For example, as shown in FIG. 2c), the functional group is a trialkylsilyl group such as a trimethoxysilyl group or triethoxysilyl group that forms a siloxane bond with a hydroxyl group on the surface of the first electrode layer, such as a trichlorosilyl group. A trihalosilyl group is preferred. Since these functional groups form a strong covalent bond with the material of the electrode layer, there is an effect that the lifetime of the organic device can be extended. In FIG. 2c), R represents lower alkyl having 1 to 4 carbon atoms, A represents a functional group that reacts with the functional group of the π-conjugated molecule in the second layer, Ar represents aryl, unsaturated aliphatic hydrocarbon, and the like.

  In addition, the reactive group of the silane coupler site is monosubstituted (monofunctional), for example, a dimethylalkoxysilyl group or a dimethylhalosilyl group is bonded to the hydroxyl group on the surface of the first electrode layer in a one-to-one relationship. Since there is no bond that reacts with the silane coupling agent without bonding to the layer, the film is oriented in a substantially vertical direction without being influenced by adjacent molecules. Therefore, it becomes possible to efficiently inject or take out carriers from the first electrode layer in a substantially vertical direction (inside the organic layer).

Next, the position of the bond provided to the π-conjugated molecular layers after the second layer will be described.
First, the position in the main chain skeleton of the bond is given to two functional groups far from each other for the purpose of orienting the π-conjugated molecule in a substantially vertical direction and extending the conjugation of the π-conjugated molecular chain. It is preferable. Specifically, the para position is preferable for a 6-membered ring, and the 2- and 5-positions are preferable for a 5-membered ring (FIGS. 2a) and b)).

  In other words, by attaching functional groups to such positions, π-conjugated molecular layers can be stacked in a substantially vertical direction, so that the molecular chain length of a laminate composed of π-conjugated molecules, that is, the thickness of the organic layer can be controlled. The effect is possible. In addition, the number of π electrons involved in the conjugation of the main chain increases and delocalization increases, so that carrier mobility can be improved. In addition, the para-position of the six-membered ring and the six-membered para-substituted acetylene are not bent in the molecule and have a one-dimensional structure, so that the orientation of the π-conjugated molecule is higher. Therefore, carrier mobility can be further improved.

Next, the types of functional groups and reaction modes of the π-conjugated molecular layers in the second and subsequent layers will be described. The reaction mode varies depending on the functional groups of the preceding and subsequent molecular layers, but the π-conjugated bonds are connected without breaking. A mode is preferred. Preferred π-conjugated molecule functional group and reaction mode combinations include Sonogashira et al., Tetrahedron lett., 1975, 50, 4467, terminal acetylene and halogen, Suzuki with boron compound and halogen. Coupling (N. Miyaura and A. Suzuki, J. Chem. Commun., 1979, 866), Wuttig reaction between aldehyde and phosphorus ylide (G. Wittig and U. Schoelkopf, OSC, 1973, 5,751), terminal ethylene and halogen Or the Heck reaction with an amine (M. Heck et al., J. Org. Chem., 1977, 42, 3903) etc. are mentioned (FIG. 2d)).

  Furthermore, as shown in FIG. 2e), when a Sonogashira coupling of terminal acetylene and halogen is used, an organic layer composed of a π-conjugated molecule of an arylene ethynylene skeleton having high planarity and high yield under mild conditions. Obtainable. If the molecule has a functional group at the para position of a 6-membered aromatic ring, an organic layer composed of a π-conjugated molecule having a linear structure can be obtained.

  In addition, when Suzuki coupling of an aromatic substituted boron compound and an aromatic substituted halogen is used, an organic layer composed of a polycyclic π-conjugated molecule such as terphenylene or terthiophene can be obtained. If it is terphenylene, the polarization characteristic by the helical structure of the main chain can be obtained. Since terthiophene provides an organic layer having a high molecular chain planarity, carrier mobility can be improved.

Next, a preferred form of the molecular layer for each device to be applied will be described.
First, a photoelectric conversion element usually includes p-type and n-type π-conjugated molecular layers.

  As a p-type π-conjugated molecular layer (p-type molecular layer), a hydrocarbon-based 6-membered aromatic ring, pyrrole, thiol, furan, etc. as shown in FIG. 3a) and those substituted with ethylene or acetylene A layer consisting of the molecules is preferred. In FIG. 3a), X means N, S, O or the like. Furthermore, the molecules constituting the π-conjugated molecular layer preferably have a phenylene ethynylene skeleton or a phenylene vinylene skeleton. Molecules having this skeleton are preferable because they have high planarity in the molecular chain direction and can move carriers using the molecular chain as a conductive path. Examples of the molecular layer having this skeleton include a stack of styrene or ethynylbenzene, and an alternate stack of 1,4-diethenylbenzene or 1,4-diethynylbenzene and benzene. The number of layers varies depending on the type of π-conjugated molecule, but 2 to 20 layers are preferable.

  In particular, the phenylene ethynylene skeleton is more preferable because excitons generated at the interface by light irradiation can be efficiently transported to the electrode layer.

  Next, as the n-type π-conjugated molecular layer (n-type molecular layer), as shown in FIG. 3b), a layer composed of pyridine, oxadiazole, silole and molecules to which ethylene or acetylene is added is preferable. Further, for the same reason as the p-type molecular layer, a molecule having the same phenylene ethynylene skeleton or phenylene vinylene skeleton is preferable. Specifically, as the n-type molecular layer, a stack of ethenyl pyridine or ethynyl pyridine, or an alternate stack of 2,5-diethenyl pyridine or 2,5-diethynyl pyridine and benzene is preferable. The number of layers varies depending on the type of π-conjugated molecule, but 2 to 20 layers are preferable.

  In addition to the n-type and p-type molecular layers, other layers that normally constitute the photoelectric conversion element may be included. Examples of such a layer include an antenna molecule layer for collecting light.

  Next, in the case of an electroluminescent element, a hole transporting molecular layer composed of molecules as shown in FIG. 4a), a luminescent molecular layer composed of molecules as shown in FIG. 4b), and a structure as shown in FIG. 4c). It is preferable to include an electron transporting molecular layer made of a compound. The number of layers varies depending on the type of π-conjugated molecule, but in the case of a hole transporting molecular layer, 2 to 10 layers are in the case of a light emitting molecular layer, and in the case of 2 to 10 layers of an electron transporting molecular layer, 2 to 2 Ten layers are preferred.

  The hole transporting molecular layer and the electron transporting molecular layer are preferably of a similar skeleton in consideration of the balance between hole mobility and electron mobility. For example, ethynylbenzene or 1,4-diethynylbenzene is preferably used for the hole transporting molecular layer, and ethenylpyridine or ethynylpyridine is preferably used for the electron transporting molecular layer.

  Next, the second electrode layer 14 is preferably made of a material having a work function difference lower than that of the first electrode layer by 0.4 eV or more in consideration of application to a photoelectric conversion element and an electroluminescence element. Specific combinations of the first electrode layer and the second electrode layer include ITO and aluminum in consideration of the stability of the cathode.

  Next, the manufacturing method of the organic device of this invention is demonstrated using FIG. 5 a)-e) corresponding to the manufacturing method of the organic device of FIG.

  First, the first electrode layer 12 is formed on the substrate 11 by sputtering, ion plating, vacuum deposition, plating, or the like (FIG. 5a). This step is not necessary when the first electrode layer also serves as the substrate. Then, the 1st electrode layer 12 produces | generates a hydroxyl group on the surface of a 1st electrode layer in order to make it react with a silane coupling agent by performing oxygen plasma processing as needed.

  Next, as shown in FIG. 5b), a first π-conjugated molecular layer 13-1 is formed on the first electrode layer 12 by a π-conjugated molecule (silane coupling agent) as shown in FIG. 2c). To do. Examples of the forming method include a liquid phase method and a gas phase method. The liquid phase method is a method in which a π-conjugated molecule layer is formed as a monomolecular layer by dissolving a π-conjugated molecule in a solvent such as toluene or acetone and immersing the first electrode layer there for several hours. On the other hand, in the vapor phase method, the first electrode layer and the π-conjugated molecule are placed in a heat-resistant, pressure-resistant vessel and heated, whereby the reaction between the vapor of the π-conjugated molecule and the first electrode layer causes the π-conjugated molecule layer 13-1. Is a method of forming

  Since the liquid phase method can be used as long as the π-conjugated molecule is dissolved in a solvent, it can be applied to many molecules. In particular, it is suitable for those having a large molecular weight that are difficult to be vaporized. However, when a molecule that is easily polymerized, such as a low-molecular polyfunctional silane coupling agent containing trialkoxysilane, is used, the generated oligomer component may be adsorbed to the substrate in the liquid phase method. Therefore, when using a low molecular polyfunctional silane coupling agent, it is preferable to use a gas phase method.

Next, the lamination of the π-conjugated molecular layers after the second layer will be described.
The second and subsequent π-conjugated molecular layers can be usually formed by a liquid phase method. That is, the π-conjugated molecule corresponding to the second layer is dissolved in the solvent, then the reaction catalyst is added to the solution, and then the substrate on which the first π-conjugated molecule layer 13-1 is laminated is immersed and stirred. As a result, the second π-conjugated molecular layer 13-2 can be formed (FIG. 5c)).

  Next, the procedure of repeated lamination after the second layer will be described. Preferred stacking methods include a method of repeatedly stacking molecules having functional groups that can react one by one in a molecule, a molecule having two identical substituents, and a molecule having two functional groups that react with the same. A method of alternately laminating is preferred. This will be schematically described with reference to FIG. 6. The former method is (A-B type (FIG. 6a))), and the latter method is (A-A + B-B type (FIG. 6b))). is there.

  In the AB type, after using a molecule AB ′ (B ′ is a protected functional group B) in which the functional group B is protected for the purpose of preventing self-reaction between molecules, the AB ′ is laminated. It is preferable to perform deprotection. In this method, only one type of molecule needs to be prepared, and it is not necessary to use two types of molecules, so that the manufacturing cost can be reduced. Also, since only one kind of molecule is used, the reaction mode of the functional group B exposed on the surface of the uppermost π-conjugated molecular layer and the functional group A of the molecule in the solution is always the same. The effect of simplicity also occurs.

  On the other hand, in the AA + BB type, there is little trouble of protecting and deprotecting the functional group B as in the AB type. In addition, for example, if a π-conjugated molecule having a small molecular size, rigid, and a functional group attached to each other is used, the π-conjugated molecule reacts with the substrate in one substitution, and is substantially perpendicular to the substrate. It is possible to stack molecular layers arranged in a layer.

  Next, the lamination procedure will be described with specific functional groups and reaction modes. By using a combination of a functional group and a reaction mode as shown in FIG. 2d), it is possible to connect the π-conjugated molecular layers while maintaining the π-conjugated bond. For example, in the case of stacking by Sonogashira coupling of an aryl halide and ethynylaryl, an organic layer composed of a π-conjugated molecule of an arylene ethynylene skeleton having high planarity and high yield can be obtained under mild conditions. Further, if the lamination is performed by Suzuki coupling of an aryl boron compound and an aryl halide, an organic layer composed of a polycyclic π-conjugated molecule such as terphenylene or terthiophene can be obtained.

  Therefore, according to such a stacking method, π-conjugated molecules are arranged in the same direction as the carrier transport direction, and the formed π-conjugated molecular chain can be used as a conductive path. Therefore, the carrier transport efficiency is increased, and if it is an organic EL element, the light emission efficiency is improved, and if it is an organic solar cell, the conversion efficiency is improved.

  In general, a π-conjugated molecule that is linked to a higher order and has a large number of conjugated π-electrons has poor solubility and a large molecular weight. Therefore, it is very difficult to first synthesize this π-conjugated molecule and then immobilize it on a substrate by a liquid phase or gas phase method. On the other hand, according to the present invention, since the reaction is repeated on the solid surface, if the molecule is dissolved in the solvent, the solubility of the compound constituting the finally formed organic layer is not considered, and the device Can design. In addition, the organic layer thickness can be freely controlled and the π-conjugated chain length can be freely designed at the stacking stage. As a result, it becomes possible to control HOMO and LUMO and to save the purification work after the π-conjugated molecule synthesis (FIG. 5d).

  Next, a method for manufacturing an organic layer having a pn junction photoelectric conversion function and an electroluminescence function using the above lamination method will be described.

  In the case of a device having a pn junction photoelectric conversion function, a p-layer is formed by repeatedly laminating π-conjugated molecular layers exhibiting p-type as shown in FIG. 3a), and then as shown in FIG. 3b). It is preferable to produce an organic layer by forming an n layer by repeatedly laminating n-type π-conjugated molecular layers. At this time, the amount of excitons generated by light irradiation increases as the thickness of the p layer and n layer obtained by stacking increases. Moreover, since the molecular chain can be used as a conductive path, the mobility of excitons is high, and high conversion efficiency is possible.

  In the case of a device having an electroluminescent function, a hole transport layer as shown in FIG. 4 is repeatedly laminated to form a hole transport layer, and a light emitting molecule is repeatedly laminated to form a light emitting layer. It is preferable to produce an organic layer by repeatedly stacking transportable molecules to form an electron transport layer. The obtained organic layer has the effect of improving the carrier transport property using the molecular chain as a conductive path, and the light emitting molecules are oriented in one direction, so that the light is emitted without scattering, and has high brightness and high This produces an effect that a device with luminous efficiency can be obtained.

  Finally, a method for forming the second electrode layer 14 will be described. The second electrode layer 14 can be formed on the organic layer by sputtering, ion plating, vacuum deposition, plating, or the like. By forming the second electrode layer 14, the device of FIG. 1 can be produced (FIG. 5e)).

7a) to 8i) schematically show a method for producing the organic photoelectric conversion element of the present invention.
First, as shown in FIG. 7a), an ITO electrode 72 was formed as a first electrode layer on a quartz substrate 71 of 25 × 25 mm. Thereafter, etching was performed using hydrochloric acid to perform patterning, and ultrasonic cleaning was performed with chloroform for 20 minutes, followed by 20 minutes with a mixed solution of acetone and ethanol. Next, as shown in FIG. 7b), the surface was subjected to hydroxylation treatment with oxygen plasma.

  Next, as shown in FIG. 7c), a first π-conjugated molecular layer 73 was formed. Specifically, 50 ml of a 0.10 mol / l toluene solution of dimethylethoxyethynylsilane was poured into a Teflon (registered trademark) petri dish, the substrate was immersed therein, heated to 40 ° C., and stirred for 3 hours. After washing with toluene, the π-conjugated molecular layer 73 was obtained by ultrasonic washing with acetone.

When the absorbance was measured with an ultraviolet-visible spectrophotometer, the molecular weight adsorbed on the substrate was 5.8 × 10 ⁻¹⁰ mol / cm ⁻² (calculated from the molar extinction coefficient of dimethylethoxyethynylsilane). Incidentally, since the calculated adsorption molecular weight when dimethylethoxyethynylsilane is spread on the electrode layer in the closest packing is 5.3 × 10 ⁻¹⁰ mol / cm ⁻² , the obtained π-conjugated molecular layer 73 is It was supported that it was arranged in high density.

  When the film thickness was measured with a spectroscopic ellipsometer, an increase of 3.6 mm was confirmed. On the other hand, structural optimization was performed when dimethylethoxyethynylsilane was standing vertically on the ITO electrode and bonded to a hydroxyl group by structural optimization calculation of Gaussian 03 package PM3 (manufactured by GAUSSIAN, INC.). As a result, the height of the terminal acetylene hydrogen from the electrode is 3.1 mm, and the case where the acetylene stands in an orientation of 56 ° with respect to the first electrode layer is the most optimal structure in calculation. From the obtained film thickness, it was confirmed that dimethylethoxyethynylsilane was arranged at high density and oriented in a substantially vertical direction (77 ° with respect to the electrode).

  Next, as shown in FIG. 7d), a p-type molecular layer 74 was formed. (4-Bromo-phenylethynyl) trimethylsilane (2.53 g, 10.0 mmol) was used as a molecule for forming the second layer, and palladium chloride (0.0177 g, 0.100 mmol), copper iodide ( 0.0143 g, 0.200 mmol) and triphenylphosphine (0.0525 g, 0.200 mmol) were added and dissolved in diethylamine (100 ml) and tetrahydrofuran (40 ml). The board | substrate with which the 1st layer was laminated | stacked was added to the obtained solution, and it stirred at room temperature for 6 hours. The substrate was taken out, washed with THF, and the attached amine salt was removed by ultrasonic cleaning with water. In FIG. 7d), TMS means a trimethylsilyl group.

  When the film thickness was measured with a spectroscopic ellipsometer, an increase of 10.8 mm was confirmed (calculated value 10.3 mm (at 77 ° orientation)).

  Furthermore, deprotection was performed as shown in FIG. In order to remove the protective group for the trimethylsilyl group, a 0.01 mmol / l potassium hydroxide aqueous solution was added to a Teflon petri dish, and the substrate was immersed therein and stirred at room temperature for 1 hour. After ultrasonic cleaning with water, the film thickness was measured with a spectroscopic ellipsometer, and a decrease of 4.0 mm was confirmed (calculated value: 3.8 mm (at 77 ° orientation)). Further, when the absorbance was measured with an ultraviolet-visible spectrophotometer, the spectrum of the maximum absorption wavelength was shown at 330 nm, and an increase in absorbance was confirmed. From this, it was supported that the second layer was laminated in a high yield and oriented in a substantially vertical direction.

  Next, the third and subsequent layers were laminated as shown in FIG. 7f) by repeating FIG. 7d) and e). Specifically, (4-bromo-phenylethynyl) trimethylsilane was laminated under the same conditions as in the second layer lamination, and deprotection was performed. By repeating this operation, up to the sixth layer was laminated. The maximum absorption wavelength of the spectrum obtained by measuring the absorbance of the organic layer with an ultraviolet-visible spectrophotometer was 550 nm, and the film thickness from the electrode measured with a spectroscopic ellipsometer was 45.4 mm (calculated value 47.2 mm (at 77 ° orientation)). It was.

Next, an n-type molecular layer 75 was formed as shown in FIG.
In the second layer lamination procedure, (4-bromo-phenylethynyl) trimethylsilane was changed to 2-bromo-5-trimethylsilylethynylpyridine (2.54 g, 10 mmol) as a precursor of the n-type molecular layer. Except for this, lamination was repeated in the same procedure (FIG. 8g), FIG. 8h)). The maximum absorption wavelength of the spectrum obtained by measuring the absorbance of the organic layer with an ultraviolet-visible spectrophotometer was 600 nm, and the film thickness from the electrode by the spectroscopic ellipsometer was 82.9 mm (calculated value 86.1 mm (at 77 ° orientation)). It was.

  Next, the second electrode layer 76 was formed. A mask capable of forming an Al 2 × 25 mm pattern was attached on the n-type π-conjugated molecular layer, and an Al electrode (second electrode layer) 74 was formed by vacuum deposition to produce an organic solar cell (FIG. 8j). )).

Next, the solar cell characteristics were measured. All measurements were performed in air, and white light from a 150 W halogen tungsten lamp was collected on the organic solar cell as a light source. The light intensity measured with an optical power meter was ² mW / cm ² . In order to determine the photoelectric conversion efficiency, the current-voltage characteristics were measured by measuring the current value with an electrometer while applying a voltage, and recorded in a computer through a GP-IB interface. Solar cell characteristics such as open electromotive force (Voc), short-circuit photocurrent density (Jsc), fill factor (FF), and photoelectric conversion efficiency (η) were determined from this current-voltage curve.

Open electromotive force: 0.55 V, short-circuit photocurrent density: -5.4 × 10 ⁻² mA / cm ² , fill factor: 0.70, photoelectric conversion efficiency: 1.0% .

  Here, the fill factor is given by a ratio of FF = (maximum output that can be actually extracted by the operation of the organic solar cell / output of Jsc × Voc watt that can be extracted if the organic solar cell is ideally operated). Value. Further, the photoelectric conversion efficiency is a value given by η (%) = (electric output that can be taken out / incident light energy) × 100.

  According to the organic solar cell, π-conjugated molecules are arranged in the same direction as the carrier transport direction, and the π-conjugated molecular chain can be used as a conductive path, so that carrier transport efficiency increases and conversion efficiency can be improved. became. As a result, a more efficient device could be fabricated.

It is the schematic of the organic device of this invention. It is a figure which shows an example of (pi) conjugated compound which can be used for the organic device of this invention. It is a figure which shows an example of (pi) conjugated compound which can be used for the organic device of this invention. It is a figure which shows an example of (pi) conjugated compound which can be used for the organic device of this invention. It is the schematic which shows the manufacturing process of the organic device of this invention. It is the schematic which shows the manufacturing process of the organic device of this invention. It is the schematic which shows the manufacturing process of the organic solar cell of an Example. It is the schematic which shows the manufacturing process of the organic solar cell of an Example.

Explanation of symbols

11: Substrate, 12: First electrode layer, 13: π-conjugated molecular layer, 14: Second electrode layer, 15: Organic molecule (π-conjugated molecule), 13-1: First π-conjugated molecular layer, 13 -2: π-conjugated molecular layer of second layer, 71: quartz substrate, 72: ITO electrode, 73: π-conjugated molecular layer of first layer, 74: p-type molecular layer, 75: n-type molecular layer, 76 : Al electrode

Claims (8)

The first electrode layer, the organic layer, and the second electrode layer are provided in this order, and the organic layer includes a plurality of π-conjugated molecular layers, and the π-conjugated molecular layer in contact with the first electrode layer is the first electrode layer. Covalently bonded to the electrode layer, oriented in a direction substantially perpendicular to the surface of the first electrode layer, adjacent π-conjugated molecular layers are covalently bonded, and the π-conjugated molecular layer has a linear structure is composed of a conjugated molecule, wherein the organic layer was characterized Rukoto that the aromatics π-conjugated molecular layer derived from the product and π-conjugated molecular layer derived from the acetylene having a layered structure which is covalently bonded alternately organic device. The organic device according to claim 1 , wherein the π-conjugated molecule is composed of a π-conjugated molecule having a structure with high planarity in the main chain direction.   3. The organic device according to claim 1, wherein any one of the plurality of π-conjugated molecules constituting the plurality of π-conjugated molecular layers is composed of a molecule containing a heterocyclic ring. The plurality of π-conjugated molecules are composed of π-conjugated molecules indicating a p-type semiconductor and π-conjugated molecules indicating an n-type semiconductor, and the organic layer is a π-conjugated molecule indicating a p-type semiconductor on the first electrode layer side. The organic device according to any one of claims 1 to 3, further comprising a layer of π-conjugated molecules including an n-type semiconductor on the second electrode layer side. A first step of laminating a first π-conjugated molecular layer on the first electrode layer so as to be oriented in a substantially vertical direction with respect to the surface of the first electrode layer while being covalently bonded to the first electrode layer. And a second step of laminating the second and subsequent π-conjugated molecular layers on the first π-conjugated molecular layer while covalently bonding to adjacent π-conjugated molecular layers, Comprising a third step of forming a second electrode layer on an organic layer comprising a plurality of π-conjugated molecular layers obtained in two steps, wherein the π-conjugated molecular layer is composed of π-conjugated molecules having a linear structure. the organic layer is method of manufacturing an organic device characterized by Rukoto that having a stacked structure in which a π-conjugated molecular layer derived from π-conjugated molecular layer and acetylene derived from an aromatic compound is covalently bonded alternately. The π-conjugated molecular layer in the second step is derived from a π-conjugated molecule having two functional groups at positions apart from each other, and a plurality of layers are stacked by repeating a condensation reaction of functional groups adjacent in the stacking direction. The manufacturing method of the organic device of Claim 5 . The π-conjugated molecule having the two functional groups is a molecule in which one functional group is protected, the π-conjugated molecule layer in the second step is used, and the other functional group of the protected molecule is used as the π-conjugated molecule. The manufacturing method of the organic device of Claim 6 including the process laminated | stacked by repeating the process laminated | stacked by making it react with the functional group of a layer, and the process deprotecting the protected molecule | numerator. The said covalent bond is formed by the cross coupling of an aryl halide and ethynyl aryl, or the cross coupling of an aryl boron compound and an aryl halide, As described in any one of Claims 5-7 characterized by the above-mentioned. Manufacturing method of organic device.

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