JP2012142365A - Organic electroluminescent element and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element, composed of laminated plural layers, which is less liable to cause short-circuit defects and therefore exhibits high efficiency and long life.SOLUTION: The present invention relates to an organic EL element comprising: an anode; an organic EL layer which includes a hole injection layer formed on the anode, a hole transport layer formed on the hole injection layer and at least a luminous layer formed on the hole transport layer; and a cathode which is formed on top of the organic EL layer. The organic EL element is characterized in that the hole injection layer contains a high polymer material, that the hole transport layer includes one or more polymer layers formed on the hole injection layer and one or more low molecular layers formed on the one or more polymer layers, and that the luminous layer contains a low molecular material.

Description

  The present invention relates to an organic electroluminescence element in which a plurality of organic layers are laminated.

  An organic electroluminescence element that sandwiches an organic layer such as a light emitting layer between a pair of electrodes and emits light by applying a voltage between both electrodes (hereinafter, electroluminescence may be abbreviated as EL) is visible by self-coloring. Has high impact resistance, excellent impact resistance because it is an all-solid-state element unlike liquid crystal elements, has a high response speed, is less affected by temperature changes, and has a large viewing angle. Therefore, the use as a light-emitting element in a display device or a lighting device is attracting attention.

As an organic EL element, an element in which a plurality of organic layers are laminated between an anode and a cathode is known.
The material of the organic layer constituting the organic EL element is roughly classified into a low molecular material and a high molecular material. In general, a vacuum film forming method is the mainstream as a method for forming an organic layer using a low molecular material, and a coating method is a mainstream method for forming an organic layer using a polymer material.

  The vacuum film-forming method has the advantage that it can be easily laminated, constitutes a multilayer structure with functional separation, and achieves high efficiency and long life. On the other hand, the coating method is advantageous in terms of cost as compared with the vacuum film forming method, and has an advantage that the area can be easily increased.

However, since the film thickness of the organic layer constituting the organic EL element is thin, in the vacuum film formation method, if there is foreign matter adhesion, protrusions, or depressions on the surface of the electrode that is the base of the organic layer, There is a problem that irregularities occur and short-circuit defects occur.
On the other hand, in the coating method, by applying a coating liquid in which an organic material is dissolved or dispersed in a solvent, it is possible to cover foreign matters, protrusions, and dents, and to suppress the occurrence of short circuit defects.

On the other hand, in the coating method, when a plurality of organic layers are laminated, the lower organic layer may be dissolved in the upper organic layer forming coating solution when the upper organic layer is formed. There is a problem that there is. In addition, when the lower organic layer is dissolved, it causes light emission unevenness and has problems such as poor efficiency and lifetime.
Therefore, when laminating a plurality of organic layers, an organic layer is often formed by a vacuum deposition method after forming an organic layer by a coating method in combination with a coating method and a vacuum deposition method. Yes.
Further, in order to laminate a plurality of organic layers by a coating method, it has been proposed to make the lower organic layer insoluble in the solvent of the upper organic layer forming coating solution (see, for example, Patent Document 1). ). In Patent Document 1, a curable binder or a material whose solubility is changed by the action of heat energy or radiation is used for the lower organic layer, or the lower organic layer and the upper organic layer have different solubility. It is disclosed that the lower organic layer is made insoluble in the solvent of the upper organic layer forming coating solution by using a material. Conventionally, for example, an aqueous dispersion of polythiophene-polystyrenesulfonic acid (PEDOT-PSS) is used for the hole injection layer, and a two-layer organic layer is used for the light-emitting layer using a coating liquid in which a polymer is dispersed in an organic solvent. Layering is done.

JP 2008-251270 A

In an organic EL device having a multilayer structure, in order to efficiently confine holes and electrons in the light emitting layer, and to suppress deterioration of characteristics due to injection of holes or electrons to the counter electrode side, It is desirable to prevent penetration of holes or electrons. For example, it has been reported that the characteristics of the organic EL element deteriorate due to the electron injection into the hole injection layer of the PEDOT-PSS described above.
However, it is very important to select the organic layer material so that the lower organic layer is insoluble in the upper organic layer forming coating solution and has a hole or electron blocking property. Have difficulty.

  The present invention has been made in view of the above-mentioned problems, and provides an organic EL element having a plurality of organic layers stacked with few short-circuit defects and high characteristics such as efficiency and lifetime. The main purpose is to do.

  To achieve the above object, the present invention provides an anode, a hole injection layer formed on the anode, a hole transport layer formed on the hole injection layer, and a hole transport layer. An organic EL device having an organic EL layer having at least a formed light emitting layer and a cathode formed on the organic EL layer, wherein the hole injection layer contains a polymer material, and the hole transport The layer has one or more polymer layers formed on the hole injection layer and one or more low molecular layers formed on the one or more polymer layers, and the light emitting layer Contains an organic EL element characterized by containing a low molecular material.

  According to the present invention, two layers of a hole injection layer containing a polymer material and a polymer layer constituting the hole transport layer are laminated on the anode, and a layer using these polymer materials Can be formed by a coating method, so that even when foreign matter, protrusions, dents, etc. are present on the anode surface, these foreign matter, protrusions, dents, etc. are covered and the occurrence of short circuit defects can be suppressed. . Further, according to the present invention, since the polymer layer and the low molecular layer are laminated in the hole transport layer, functional separation is possible, and a material having excellent electron blocking property can be used for the low molecular layer. Furthermore, in the light emitting material used for the light emitting layer, the low molecular weight material has higher luminous efficiency and longer life than the polymer material, and is superior in material performance. Therefore, in the present invention, characteristics such as efficiency and life can be improved.

  In the above invention, one of the hole injection layer and the polymer layer directly formed on the hole injection layer contains a high polarity polymer material, and the other contains a low polarity polymer material. It is preferable to contain. Even if repelling occurs due to the relationship between the surface polarity of the anode and the polarity of the polymer material of the hole injection layer, and the surface of the hole injection layer is uneven, the polymer material of the hole injection layer and the hole injection layer It is because the unevenness | corrugation can be covered and the generation | occurrence | production of a short circuit defect can be prevented because polarity differs from the polymer material of the polymer layer formed directly on the top. In addition, the polarity of the polymer material of the hole injection layer and the polymer material of the polymer layer formed directly on the hole injection layer is different, so that the polymer layer forming coating can It is because it can suppress that a hole injection layer melt | dissolves in a liquid.

  In this case, it is more preferable that the hole injection layer contains the high-polarity polymer material. In general, since the surface polarity of the anode is high, the hole injection layer formed on the anode preferably contains a highly polar polymer material.

  The present invention is also a method for producing an organic EL element having an organic EL layer forming step of forming an organic EL layer on the anode, wherein the organic EL layer forming step comprises applying a polymer material on the anode by a coating method. A hole injection layer forming step for forming a hole injection layer to be contained, a polymer layer forming step for forming one or more polymer layers on the hole injection layer by a coating method, and a vacuum film forming method A low molecular layer forming step of forming one or more low molecular layers on the one or more polymer layers, wherein the one or more polymer layers and the one layer are formed on the hole injection layer. A hole transport layer forming step of forming a hole transport layer having the above low molecular layer and a light emitting layer forming step of forming a light emitting layer containing a low molecular material on the hole transport layer by a vacuum film formation method The manufacturing method of the organic EL element characterized by having.

  According to the present invention, since two layers of a hole injection layer containing a polymer material and a polymer layer constituting a hole transport layer are laminated on the anode by a coating method, foreign matter, protrusions are formed on the anode surface. Even when a depression or the like is present, these foreign matters, protrusions, depressions and the like can be covered, and the occurrence of short-circuit defects can be suppressed. In addition, according to the present invention, since the hole transport layer is formed by laminating the polymer layer and the low molecular layer, functional separation is possible, and a material having excellent electron blocking property can be used for the low molecular layer. . Furthermore, in the light emitting material used for the light emitting layer, the low molecular weight material has higher luminous efficiency and longer life than the polymer material, and is superior in material performance. Therefore, in the present invention, it is possible to obtain an organic EL element having excellent characteristics such as efficiency and lifetime.

  In the above invention, one of the hole injection layer and the polymer layer directly formed on the hole injection layer contains a high polarity polymer material, and the other contains a low polarity polymer material. It is preferable to contain. Even if repelling occurs due to the relationship between the surface polarity of the anode and the polarity of the polymer material of the hole injection layer, and the surface of the hole injection layer is uneven, the polymer material of the hole injection layer and the hole injection layer It is because the unevenness | corrugation can be covered and the generation | occurrence | production of a short circuit defect can be prevented because polarity differs from the polymer material of the polymer layer formed directly on the top. In addition, the polarity of the polymer material of the hole injection layer and the polymer material of the polymer layer formed directly on the hole injection layer are different, so that when the polymer layer is formed by the coating method, hole injection is performed. It is because it can suppress that a layer melt | dissolves.

  In this case, it is more preferable that the hole injection layer contains the high-polarity polymer material. As described above, since the surface polarity of the anode is generally high, the hole injection layer formed on the anode preferably contains a highly polar polymer material.

  In the present invention, it is possible to prevent the occurrence of a short-circuit defect, and to achieve an effect of achieving high efficiency and long life.

It is a schematic sectional drawing which shows an example of the organic EL element of this invention. It is process drawing which shows an example of the manufacturing method of the organic EL element of this invention.

  Hereinafter, the organic EL device of the present invention and the manufacturing method thereof will be described in detail.

A. Organic EL device The organic EL device of the present invention is formed on an anode, a hole injection layer formed on the anode, a hole transport layer formed on the hole injection layer, and a hole transport layer. An organic EL device having at least an organic EL layer having a light emitting layer and a cathode formed on the organic EL layer, wherein the hole injection layer contains a polymer material, and the hole transport layer Has one or more polymer layers formed on the hole injection layer and one or more low molecular layers formed on the one or more polymer layers, and the light emitting layer has It is characterized by containing a low molecular material.

The organic EL element of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic cross-sectional view showing an example of the organic EL element of the present invention. An organic EL element 1 illustrated in FIG. 1 includes a substrate 2, an anode 3 formed on the substrate 2, an anode 3, and a hole injection layer 4, a hole transport layer 11, a light emitting layer 7, and an electron. It has an organic EL layer 12 in which a transport layer 8 and an electron injection layer 9 are sequentially laminated, and a cathode 10 formed on the organic EL layer 12. In this organic EL element 1, the hole injection layer 4 contains a polymer material, the light emitting layer 7 contains a low molecule, and the electron transport layer 8 and the electron injection layer 9 also contain a low molecule material. The hole transport layer 11 has a polymer layer 5 and a low molecular layer 6 formed on the polymer layer 5.

According to the present invention, two layers of a hole injection layer containing a polymer material and a polymer layer constituting the hole transport layer are laminated on the anode, and a layer using these polymer materials Can be formed by a coating method, so that even when foreign matter, protrusions, depressions, etc. are present on the anode surface, these foreign matters, protrusions, depressions, etc. can be covered.
Further, according to the present invention, since the polymer layer and the low molecular layer are laminated in the hole transport layer, functional separation is possible, and a material having excellent electron blocking property can be used for the low molecular layer. Further, in the hole transporting material used for the hole transporting layer, the low molecular material has an advantage that the electron blocking property is higher than that of the polymer material.
In addition, the hole transport layer can be functionally separated as described above, and a material excellent in hole injectability from the hole injection layer can be used for the polymer layer. Furthermore, in the hole transporting material used for the hole transporting layer, it is considered that the polymer material can easily inject holes from the hole injecting layer as compared with the low molecular weight material.
Furthermore, in the light emitting material used for the light emitting layer, the low molecular weight material has higher luminous efficiency and longer life than the polymer material, and is superior in material performance.
Therefore, in the present invention, characteristics such as efficiency and life can be improved.

  Further, in the hole transport layer in the present invention, functional separation is possible as described above, and one hole transport layer, particularly one polymer layer, has hole transport properties and electron blocking properties. In addition, since it is not necessary to use a material that can be dispersed or dissolved in a solvent that does not dissolve the hole injection layer, the material selectivity of the polymer layer and the low molecular layer is increased.

Further, since the low molecular layer can be formed by a vacuum film formation method, the low molecular layer can be easily laminated on the polymer layer, and such a low molecular layer is interposed between the polymer layer and the light emitting layer. By being formed, holes or electrons can be prevented from penetrating from the light emitting layer, and the life characteristics can be improved.
Hereinafter, each structure of the organic EL element of this invention is demonstrated.

1. Organic EL layer In the present invention, the organic EL layer comprises a hole injection layer formed on the anode, a hole transport layer formed on the hole injection layer, and a light emission formed on the hole transport layer. And at least a layer. In the organic EL layer, the hole injection layer contains a polymer material, the hole transport layer includes one or more polymer layers formed on the hole injection layer, and the one or more layers. And one or more low molecular layers formed on the polymer layer, and the light emitting layer contains a low molecular material. Moreover, when an organic EL layer further has an arbitrary layer between the light emitting layer and the cathode, the arbitrary layer contains a low molecular material.
Hereinafter, each structure of the organic EL layer will be described.

(1) Hole transport layer The hole transport layer in the present invention is formed on the hole injection layer. One or more polymer layers formed on the hole injection layer and the above one layer It has one or more low molecular layers formed on the above polymer layer.
Hereinafter, each configuration of the hole transport layer will be described.

(A) Polymer Layer The polymer layer constituting the hole transport layer in the present invention is formed on the hole injection layer and contains a polymer material.
The “polymer material” refers to a material having an arbitrary repeating unit. The weight average molecular weight of the polymer material may be 1000 or more. As long as it has a repeating unit, an oligomer or the like having a small number of repeating units may be used.

  The polymer material contained in the polymer layer is not particularly limited as long as it is a hole transporting polymer material that can stably transport holes injected from the hole injection layer into the light emitting layer. is not. Among these, the hole transporting polymer material preferably has a high hole mobility. Examples of such hole transporting polymer materials include arylamine derivatives, anthracene derivatives, carbazole derivatives, thiophene derivatives, fluorene derivatives, distyrylbenzene derivatives, and spiro compounds. Specific examples of the arylamine derivative include copoly [3,3′-hydroxy-tetraphenylbenzidine / diethylene glycol] carbonate (PC-TPD-DEG). Specific examples of the anthracene derivative include poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (9,10-anthracene)]. Specific examples of the carbazole derivative include polyvinyl carbazole (PVK). Specific examples of the thiophene derivative include poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (bithiophene)]. Specific examples of the fluorene derivative include poly [(9,9-dioctylfluorenyl-2,7-diyl) -co- (4,4 ′-(N- (4-sec-butylphenyl)) diphenylamine)] (TFB). Specific examples of spiro compounds include poly [(9,9-dioctylfluorenyl-2,7-diyl) -alt-co- (9,9′-spiro-bifluorene-2,7-diyl)] and the like. Can be mentioned. Further, the polymer material may be a high molecular weight material of a low molecular material described later. These materials may be used alone or in combination of two or more.

  The polymer material contained in the polymer layer may have a heat and / or photocurable functional group. This is because the stability of the polymer layer is improved. Thermal and / or photocurable functional groups include acrylic functional groups such as acryloyl groups and methacryloyl groups, or vinyl groups, vinylene groups, epoxy groups, isocyanate groups, cinnamate groups, cinnamoyl groups, coumarin groups, carbazole groups, etc. Can be mentioned. Specifically, as a polymer material in which a curable functional group is introduced in the molecule, poly [(9,9-dioctylfluorenyl-2,7-diyl) which is a fluorene derivative and has a vinyl group in the structure. ) -Alto-co- (9,9-di- {5-pentenyl} -fluorenyl-2,7-diyl)] and poly [(9,9-di- {5-pentenyl} -fluorenyl-2,7 -Diyl) -co- (4,4 '-(N- (4-sec-butylphenyl)) diphenylamine)] (thermosetting TFB).

In the present invention, one of the hole injection layer and the polymer layer directly formed on the hole injection layer contains a high polarity polymer material, and the other contains a low polarity polymer material. It is preferable.
When the hole injection layer and the polymer layer are formed by the coating method, foreign matter, protrusions, and depressions on the anode surface can be covered as described above, but the surface polarity of the anode and the coating liquid for forming the hole injection layer Depending on the relationship with the polarity, the hole injection layer forming coating solution may be repelled. When repelling occurs, the surface of the hole injection layer becomes uneven and short-circuit defects occur. Although it is possible to improve the surface irregularities by increasing the thickness of the hole injection layer and the polymer layer, the film thickness of the hole injection layer and the polymer layer is limited and positive. When the hole injection layer and the polymer layer are thickened, driving with a high voltage is required.
In contrast, when one of the hole injection layer and the polymer layer formed directly on the hole injection layer contains a high polarity polymer material and the other contains a low polarity polymer material, The polarity of the polymer material of the hole injection layer and the polymer material of the polymer layer formed directly on the hole injection layer, even when the surface of the hole injection layer is uneven due to repelling By being different, the unevenness can be covered and the occurrence of short-circuit defects can be prevented.
In addition, since the polarity of the polymer material of the hole injection layer and the polymer material of the polymer layer formed directly on the hole injection layer is different, it is contained in the hole injection layer when the polymer layer is formed. The high molecular material can be prevented from eluting, and the high molecular layer can be stably laminated on the hole injection layer.

In the present invention, the “high polarity polymer material” means a polymer material after drying when a polymer material layer made of a polymer material having a film thickness of 100 nm is dipped in toluene for 10 seconds and then dried. The layer thickness is in the range of 70 nm to 100 nm.
In the present invention, the “low polarity polymer material” means a polymer material after drying when a polymer material layer made of a polymer material having a film thickness of 100 nm is dipped in toluene for 10 seconds and then dried. The layer thickness is in the range of 0 nm to 30 nm.
Here, when the polymer material has a heat and / or photocurable functional group, the polymer material layer before curing is used for the above test.

  The term “polymer layer formed directly on the hole injection layer” refers to a polymer layer when the hole transport layer has only one polymer layer. In the case of having two or more polymer layers, the polymer layer adjacent to the hole injection layer among the two or more polymer layers.

That is, the polymer material contained in the polymer layer formed directly on the hole injection layer is preferably a high polarity polymer material or a low polarity polymer material.
The high-polarity polymer material used for the polymer layer is not particularly limited as long as it can stably transport holes injected from the hole injection layer into the light emitting layer. Examples of the hole transporting polymer material described above include those having a highly polar functional group introduced in the molecule.
The high-polarity functional group introduced into the molecule in the hole-transporting polymer material is not particularly limited as long as it can satisfy the definition of the above-described high-polarity polymer material. The polar group can be used, specifically, hydroxyl group, carbonyl group, carboxyl group, amino group, thiol group, silanol group, sulfo group, sulfonate, ammonium group, aldehyde group, amide group, sulfonamide group , Phosphoric acid group, phosphinic acid group, phosphoryl group and the like.

On the other hand, the low-polarity polymer material used for the polymer layer is not particularly limited as long as it can stably transport holes injected from the hole injection layer into the light emitting layer, For example, in the above-described hole transporting polymer material, a material in which a low-polar functional group is introduced into the molecule can be used.
The low-polar functional group introduced into the molecule in the hole-transporting polymer material may be any one that satisfies the above-mentioned definition of the low-polar polymer material, such as benzyl group, naphthyl group, etc. Aromatic hydrocarbon groups, unsaturated alkyl groups having 1 to 12 carbon atoms, vinyl groups, and the like, condensed ring compounds such as fluorene, and cyclic aliphatic compounds such as cycloalkane and cycloalkene. .

  Among them, the polymer layer formed directly on the hole injection layer preferably contains a low polarity polymer material. That is, it is preferable that the hole injection layer contains a high polarity polymer material and the polymer layer formed directly on the hole injection layer contains a low polarity polymer material. Since anodes made of inorganic oxides such as ITO generally have a high surface polarity, the hole injection layer contains a high-polarity polymer material so that the hole injection layer is uniformly formed on the anode with good adhesion. Because it can be done.

  The polymer layer may contain a low molecular material in addition to the above-described polymer material. The low molecular material used for the polymer layer is not particularly limited as long as it is a hole transporting low molecular material that can stably transport holes injected from the hole injection layer into the light emitting layer. Absent. Among these, the hole transporting low molecular weight material preferably has a high hole mobility. Examples of such hole transporting low molecular weight materials include arylamine derivatives, anthracene derivatives, carbazole derivatives, thiophene derivatives, fluorene derivatives, distyrylbenzene derivatives, spiro compounds and the like. Specific examples of the arylamine derivative include bis (N- (1-naphthyl-N-phenyl) -benzidine (α-NPD), N, N′-bis- (3-methylphenyl) -N, N′-bis. -(Phenyl) -benzidine (TPD), 4,4,4-tris (3-methylphenylphenylamino) triphenylamine (MTDATA), etc. Specific examples of anthracene derivatives include 9,10- Di-2-naphthylanthracene (DNA), etc. Specific examples of the carbazole derivative include 4,4-N, N′-dicarbazole-biphenyl (CBP), etc. Distyrylbenzene Specific examples of the derivatives include 1,4-bis (2,2-diphenylvinyl) benzene (DPVBi) and the like. Charge may be better in combination of two or more types may be used in combination.

  The polymer layer may contain an additive as long as the effects of the present invention are not impaired. For example, when the polymer material has heat and / or a photocurable functional group, the polymer layer further includes a curing agent that accelerates the curing reaction and an initiator for initiating the photoreaction. It may be. Specifically, when it has an epoxy group, it may contain a curing agent such as an acid, and when it has an ethylenic double bond, it may contain a photopolymerization initiator.

  The hole transport layer has one or more polymer layers, and the number of polymer layers may be one or more, and may be one layer, two layers, three layers, etc. One layer.

  The film thickness of the polymer layer is not particularly limited as long as the function of sufficiently transporting holes injected from the hole injection layer to the light emitting layer is exhibited, and specifically, 1 nm to 200 nm. Can be about. If the polymer layer is too thin, it is difficult to suppress the occurrence of short-circuit defects, and if the polymer layer is too thick, there is a risk of increasing the voltage. The film thickness of the polymer layer is the film thickness of one polymer layer.

As a method for forming the polymer layer, a coating method is preferably used. That is, the polymer layer is preferably a coating film.
The “coating film” means a film formed by a coating method using a coating liquid.
Here, it can be confirmed that the polymer layer is a coating film by detecting the solvent using, for example, a purge & trap-GC / MS method. Further, by observing the shape of the end portion of the polymer layer with an electron microscope or the like, it is possible to determine whether the film is a film formed by a coating method or a film formed by a vacuum film forming method.

  The method for forming the polymer layer will be described in detail in the section of “B. Method for manufacturing organic EL element” described later, and will not be described here.

(B) Low molecular layer The low molecular layer which comprises the positive hole transport layer in this invention is formed on the said 1 or more polymer layer, and contains a low molecular material.
The “low molecular weight material” means a material that does not have any repeating unit. The low molecular weight material may have a weight average molecular weight of 1000 or less.
Further, “formed on one or more polymer layers” means that when the hole transport layer has only one polymer layer, it is formed on the polymer layer. When the hole transport layer has two or more polymer layers, it means that the pore transport layer is formed on a laminate in which all polymer layers are laminated.

The low molecular material contained in the low molecular layer is not particularly limited as long as it is a hole transporting low molecular material that can stably transport holes injected from the anode into the hole transporting layer. Absent. Among these, the hole transporting low molecular weight material preferably has a high hole mobility.
As such a hole transporting low molecular weight material, for example, an inorganic material, an organic material, an organometallic complex, or the like can be used. Specific examples include arylamine derivatives, anthracene derivatives, carbazole derivatives, thiophene derivatives, fluorene derivatives, distyrylbenzene derivatives, and spiro compounds. Specific examples of the arylamine derivative include bis (N- (1-naphthyl-N-phenyl) -benzidine (α-NPD), N, N′-bis- (3-methylphenyl) -N, N′-bis. -(Phenyl) -benzidine (TPD), 4,4,4-tris (3-methylphenylphenylamino) triphenylamine (MTDATA), etc. Specific examples of anthracene derivatives include 9,10- Di-2-naphthylanthracene (DNA), etc. Specific examples of the carbazole derivative include 4,4-N, N′-dicarbazole-biphenyl (CBP), etc. Distyrylbenzene Specific examples of the derivatives include 1,4-bis (2,2-diphenylvinyl) benzene (DPVBi) and the like. Charge may be better in combination of two or more types may be used in combination.

Furthermore, it is preferable that the hole transporting low molecular weight material can prevent penetration of electrons that have moved from the cathode. This is because the recombination efficiency of holes and electrons in the light emitting layer can be increased.
As such hole transporting low molecular weight materials, specifically, N, N′-bis- (3-methylphenyl) -N, N′-bis- (phenyl) -benzidine (TPD), bis ( Triarylamines such as N- (1-naphthyl-N-phenyl) -benzidine (α-NPD) and [(triphenylamine) dimer] spirodimer (Spiro-TAD), 4,4 ′, 4 ″ -tris Starburst amines such as [3-methylphenyl (phenyl) amino] triphenylamine (m-MTDATA), 4,4 ′, 4 ″ -tris [1-naphthyl (phenyl) amino] triphenylamine (1-TNATA) And oligothiophenes such as 5,5 ″ -bis- {4- [bis (4-methylphenyl) amino] phenyl} -2,2 ′: 5 ′, 2 ″ terthiophene (BMA-3T) Raise Door can be.

  The low molecular layer may contain an additive as long as the effects of the present invention are not impaired.

  The hole transport layer has one or more low molecular layers, and the number of low molecular layers may be one or more, and may be one layer, two layers, three layers, etc. One layer.

  The film thickness of the low molecular layer is not particularly limited as long as the function of sufficiently transporting the holes injected from the hole injection layer to the light emitting layer is exhibited, and specifically, 1 nm to 200 nm. Can be about. If the low molecular layer is too thin, the electron blocking property may not be sufficiently exhibited, and if the low molecular layer is too thick, there is a risk of increasing the voltage. The film thickness of the low molecular layer is the film thickness of one low molecular layer.

Examples of the method for forming the low molecular layer include a vacuum film forming method and a coating method. Among these, the vacuum film forming method is preferably used. That is, the low molecular layer is preferably a deposited film.
The “evaporated film” means a film formed by a vacuum film forming method.
Here, it can be confirmed by an electron micrograph that the low molecular weight layer is a deposited film. Specifically, by observing the shape of the edge of the low molecular layer with an electron microscope or the like, it is determined whether the film is formed by a vacuum film forming method or a coating method. Can do.

  In addition, since the formation method of a low molecular layer is described in detail in the section of “B. Manufacturing method of organic EL element” described later, description thereof is omitted here.

(2) Hole Injection Layer The hole injection layer in the present invention is formed on the anode and contains a polymer material.
The definition of “polymer material” is the same as the polymer material contained in the polymer layer of the hole transport layer.

The polymer material used for the hole injection layer is not particularly limited as long as it is a hole injecting polymer material that can stabilize the injection of holes into the light emitting layer. Examples of such hole injecting polymer materials include arylamine derivatives, porphyrin derivatives, carbazole derivatives, and conductive polymers such as polyaniline derivatives, polythiophene derivatives, and polyphenylene vinylene derivatives. Specifically, examples of the arylamine derivative include copoly [3,3′-hydroxy-tetraphenylbenzidine / diethylene glycol] carbonate (PC-TPD-DEG). Examples of the carbazole derivative include polyvinyl carbazole (PVK). Examples of the polythiophene derivative include poly (3,4-ethylenedioxythiophene) -polystyrene sulfonic acid (PEDOT-PSS).
The above porphyrin derivatives and arylamine derivatives may be mixed with inorganic acids such as Lewis acid, tetracyanoquinodimethane (F4-TCNQ), iron chloride, vanadium and molybdenum.
Among them, the hole injecting polymer material is preferably a material whose characteristics are easily deteriorated by electron injection. In the present invention, the formation of a low molecular layer can prevent electrons from penetrating from the light emitting layer, which is useful in the case of a hole injection layer in which characteristic deterioration occurs due to electron injection. An example of such a hole injecting polymer material is PEDOT-PSS.

  In the present invention, as described above, one of the hole injection layer and the polymer layer directly formed on the hole injection layer contains a high polarity polymer material, and the other has a low polarity and a high polarity. It is preferable to contain a molecular material. The polarity of the polymer material of the hole injection layer and the polymer material of the polymer layer formed directly on the hole injection layer are different even when the surface of the hole injection layer is uneven due to repelling. This is because the irregularities can be covered and the occurrence of short-circuit defects can be prevented. In addition, when the polymer layer is formed, the polymer material contained in the hole injection layer can be prevented from being eluted, and the polymer layer can be stably laminated on the hole injection layer. .

That is, the polymer material contained in the hole injection layer is preferably a high polarity polymer material or a low polarity polymer material.
The high-polarity polymer material used for the hole-injecting layer is not particularly limited as long as it is a hole-injecting material that can stabilize the injection of holes into the light-emitting layer. In the hole-injecting polymer material, a material having a highly polar functional group introduced therein may be used.
In addition, about the highly polar functional group introduce | transduced in a molecule | numerator in a hole injectable polymeric material, it can be made to be the same as that of what was described in the term of the polymer layer of the said positive hole transport layer.
Examples of the hole-injecting polymer material in which a highly polar functional group is introduced in the molecule include a heterocyclic compound having a thiophene ring such as PEDOT-PSS, and a polyaniline / polystyrene sulfonic acid copolymer (PANI / PSS). ), And compounds having a nitrogen-containing aromatic repeating unit such as a polyaniline derivative.

On the other hand, the low-polarity polymer material used for the hole injection layer is not particularly limited as long as it is a hole injection material that can stabilize the injection of holes into the light emitting layer. Examples of the above-described hole-injecting polymer material include those having a low-polar functional group introduced in the molecule.
In addition, about the low polar functional group introduce | transduced in a molecule | numerator in a hole injectable polymeric material, it can be made to be the same as that of what was described in the term of the polymer layer of the said positive hole transport layer.

  Among these, the hole injection layer preferably contains a highly polar polymer material. Since anodes made of inorganic oxides such as ITO generally have a high surface polarity, the hole injection layer contains a high-polarity polymer material so that the hole injection layer is uniformly formed on the anode with good adhesion. Because it can be done.

  The hole injection layer may contain an additive as long as the effects of the present invention are not impaired.

  The thickness of the hole injection layer is not particularly limited as long as the function of stabilizing the injection of holes into the light emitting layer is sufficiently exerted, and specifically about 1 nm to 300 nm. can do. If the hole injection layer is too thin, it is difficult to suppress the occurrence of short-circuit defects, and if the hole injection layer is too thick, there is a risk of increasing the voltage.

As a method for forming the hole injection layer, a coating method is preferably used. That is, the hole injection layer is preferably a coating film.
In addition, about a coating film, it can be made to be the same as that of what was described in the term of the polymer layer of the said positive hole transport layer.

  Moreover, since the formation method of a positive hole injection layer is described in detail in the section of “B. Manufacturing method of organic EL element” described later, description thereof is omitted here.

(3) Light emitting layer The light emitting layer in this invention is formed on the said positive hole transport layer, and contains a low molecular material.
The definition of “low molecular weight material” is the same as the low molecular weight material contained in the low molecular weight layer of the hole transport layer.

  As the low molecular weight material used for the light emitting layer, any of a fluorescent material and a phosphorescent material can be used, and examples thereof include a dye material and a metal complex material.

Examples of dye-based materials include cyclopentadiene derivatives, tetraphenylbutadiene derivatives, triphenylamine derivatives, arylamine derivatives, oxadiazole derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, distyrylpyrazine derivatives, distyrylarylene. Derivatives, silole derivatives, carbazole derivatives, anthracene derivatives, dinaphthylanthracene derivatives, phenylanthracene derivatives, thiophene ring compounds, pyridine ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, trifumanylamine derivatives, coumarin derivatives, oxadiazole dimers , Pyrazoline dimer, phenanthroline and the like. Moreover, the compound which introduce | transduced the fluorene group and the spiro group into these can also be used.
Specifically, as the triphenylamine derivative, N, N′-bis- (3-methylphenyl) -N, N′-bis- (phenyl) -benzidine (TPD), 4,4,4-tris (3 -Methylphenylphenylamino) triphenylamine (MTDATA) and the like. Examples of the arylamine derivative include bis (N- (1-naphthyl-N-phenyl) benzidine) (α-NPD). Examples of the oxadiazole derivative include (2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole) (PBD). Examples of the dinaphthylanthracene derivative include 9,10-di-2-naphthylanthracene (DNA). Examples of the carbazole derivative include 4,4-N, N′-dicarbazole-biphenyl (CBP), 1,4-bis (2,2-diphenylvinyl) benzene (DPVBi), and the like. Examples of phenanthrolines include bathocuproin and bathophenanthroline. These materials may be used alone or in combination of two or more.

Examples of the metal complex-based material include Al, Zn, Be, Ir, Pt, etc. as a central metal, or rare earth metals such as Tb, Eu, Dy, etc., and oxadiazole, thiadiazole, phenylpyridine as a ligand. , Phenylbenzimidazole, metal complexes having a quinoline structure, and the like. Examples of the metal complex include an aluminum quinolinol complex, a benzoquinolinol beryllium complex, a benzoxazole zinc complex, a benzothiazole zinc complex, an azomethylzinc complex, a porphyrin zinc complex, a europium complex, an iridium metal complex, and a platinum metal complex.
Specifically, tris (8-quinolinol) aluminum complex (Alq ₃ ), bis (2-methyl-8-quinolinato) (p-phenylphenolate) aluminum complex (BAlq), tri (dibenzoylmethyl) phenanthroline europium complex And bis (benzoquinolinolato) beryllium complex (Bebq). These materials may be used alone or in combination of two or more.

  Further, a dopant that emits fluorescence or phosphorescence may be added to the light emitting layer for the purpose of improving the light emission efficiency and changing the light emission wavelength. Examples of such dopants include perylene derivatives, coumarin derivatives, rubrene derivatives, quinacridone derivatives, squalium derivatives, porphyrin derivatives, styryl dyes, tetracene derivatives, pyrazoline derivatives, decacyclene, phenoxazone, quinoxaline derivatives, carbazole derivatives, fluorene derivatives, and the like. Can be mentioned. Specifically, 1-tert-butyl-perylene (TBP), coumarin 6, Nile red, 1,4-bis (2,2-diphenylvinyl) benzene (DPVBi), 1,1,4,4-tetraphenyl -1,3-butadiene (TPB).

Furthermore, as a phosphorescent dopant, an organometallic complex that has a heavy metal ion such as platinum or iridium at the center and exhibits phosphorescence can be used. Specifically, Ir (ppy) ₃ , (ppy) ₂ Ir (acac), Ir (BQ) ₃ , (BQ) ₂ Ir (acac), Ir (THP) ₃ , (THP) ₂ Ir (acac), Ir (BO) ₃ , (BO) ₂ (acac), Ir (BT) ₃ , (BT) ₂ Ir (acac), Ir (BTP) ₃ , (BTP) ₂ Ir (acac), FIr6, PtOEP, etc. are used. be able to.

  Here, the light emitting layer has a function of emitting light by providing a recombination field between electrons and holes. The light emitting layer may emit blue light, green light, yellow light, orange light, red light, or other single color light, or may emit white light due to a mixture of multiple colors. It may be. White light emission can be obtained by superimposing light emission from a plurality of light emitters. The light emitting layer that emits white light may be, for example, one that obtains white light emission by superimposing two-color light emission of two types of light emitters having a predetermined peak wavelength, and three types of light emitters having a predetermined peak wavelength. It is also possible to obtain white light emission by superimposing these three colors.

  The thickness of the light emitting layer is not particularly limited as long as it can provide a function of emitting light by providing a recombination field between electrons and holes.

Examples of the method for forming the light emitting layer include a vacuum film forming method and a coating method. Among these, the vacuum film forming method is preferably used. That is, the light emitting layer is preferably a deposited film.
In addition, since it is the same as that of what was described in the term of the low molecular layer of the said positive hole transport layer about a vapor deposition film, description here is abbreviate | omitted.

  Further, the method for forming the light emitting layer is described in detail in the section “B. Method for manufacturing organic EL element” described later, and thus the description thereof is omitted here.

(4) Electron transport layer In the present invention, an electron transport layer may be formed between the light emitting layer and the cathode. The electron transport layer in the present invention contains a low molecular material.
The definition of “low molecular weight material” is the same as the low molecular weight material contained in the low molecular weight layer of the hole transport layer.

The low molecular weight material used for the electron transporting layer is not particularly limited as long as it is an electron transporting material that can stably transport electrons injected from the cathode into the light emitting layer. Especially, it is preferable that an electron transport material has a high electron mobility. Furthermore, the electron transporting material is preferably a material that can prevent penetration of holes that have moved from the anode. This is because the recombination efficiency of holes and electrons in the light emitting layer can be increased.
As such an electron transporting material, an inorganic material, an organic material, an organometallic complex, or the like can be used. Examples thereof include oxadiazoles, triazoles, phenanthrolines, silole derivatives, cyclopentadiene derivatives, aluminum complexes, and the like. Specific examples of the oxadiazole derivative include (2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole) (PBD) and the like, and phenanthroline. Examples thereof include bathocuproin, bathophenanthroline and the like, and examples of the aluminum complex include tris (8-quinolinol) aluminum complex (Alq ₃ ), bis (2-methyl-8-quinolinato) (p-phenylphenolate) aluminum complex (BAlq ) And the like.

  The film thickness of the electron transport layer is not particularly limited as long as the function of sufficiently transporting electrons injected from the cathode to the light emitting layer is exhibited.

Examples of the method for forming the electron transport layer include a vacuum film formation method and a coating method. Among these, the vacuum film formation method is preferably used. That is, the electron transport layer is preferably a vapor deposition film.
Note that the vapor deposition film and the vacuum film formation method are the same as those described in the section of the low molecular layer of the hole transport layer, and thus the description thereof is omitted here.

(5) Electron injection layer In the present invention, an electron injection layer may be formed between the light emitting layer and the cathode. When the electron transport layer is formed between the light emitting layer and the cathode, an electron injection layer is formed between the electron transport layer and the cathode. The electron injection layer in the present invention contains a low molecular material.
The definition of “low molecular weight material” is the same as the low molecular weight material contained in the low molecular weight layer of the hole transport layer.

  The low molecular material used for the electron injection layer is not particularly limited as long as it is an electron injectable material that can stabilize the injection of electrons into the light emitting layer. For example, an inorganic material, an organic material, An organometallic complex or the like can be used. Specifically, alkali metal or alkaline earth metal simple substance such as strontium, calcium, lithium and cesium; alkali metal or alkaline earth metal oxide such as magnesium oxide, strontium oxide and lithium oxide; lithium fluoride, Alkali metal or alkaline earth metal fluorides such as magnesium fluoride, strontium fluoride, calcium fluoride, barium fluoride, cesium fluoride; organic complexes of alkali metals such as polymethylmethacrylate polystyrene sodium sulfonate Can do.

  The thickness of the electron injection layer is not particularly limited as long as it has a thickness that sufficiently exhibits the function of stabilizing the injection of electrons into the light emitting layer.

Examples of the method for forming the electron injection layer include a vacuum film formation method and a coating method. Among these, the vacuum film formation method is preferably used. That is, the electron injection layer is preferably a vapor deposition film.
Note that the vapor deposition film and the vacuum film formation method are the same as those described in the section of the low molecular layer of the hole transport layer, and thus the description thereof is omitted here.

2. Anode The anode used in the present invention may or may not have optical transparency, and is appropriately selected according to the light extraction surface. When light is extracted from the anode side, the anode becomes a transparent electrode.

The anode preferably has a low resistance, and a metal material that is a conductive material is generally used, but an organic compound or an inorganic compound may be used.
As a material used for the anode, a conductive material having a large work function is preferably used so that holes can be easily injected. For example, metals such as Au, Ta, W, Pt, Ni, Pd, Cr, Cu, Mo, alkali metals, alkaline earth metals; oxides of these metals; Al alloys such as AlLi, AlCa, AlMg, MgAg, etc. Mg alloys, Ni alloys, Cr alloys, alkali metal alloys, alkaline earth metal alloys, etc .; inorganic such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium oxide Examples include oxides; conductive polymers such as metal-doped polythiophene, polyaniline, polyacetylene, polyalkylthiophene derivatives, and polysilane derivatives; α-Si, α-SiC; and the like. These conductive materials may be used alone or in combination of two or more. When two or more types are used, layers made of each material may be stacked.

  As an anode film formation method, a general electrode formation method can be used, and any of a dry process and a wet process can be applied. Examples of the dry process include physical vapor deposition (PVD) methods such as vacuum vapor deposition, sputtering, EB vapor deposition, and ion plating, or chemical vapor deposition (CVD). Further, when the anode is formed in a pattern, the patterning method is not particularly limited as long as it can be accurately formed into a desired pattern. Specifically, a photolithography method or the like is used. Can be mentioned.

3. Cathode The cathode used in the present invention may or may not have optical transparency, and is appropriately selected according to the light extraction surface. When light is extracted from the cathode side, the cathode becomes a transparent electrode.

The cathode preferably has a low resistance, and a metal material that is a conductive material is generally used, but an organic compound or an inorganic compound may be used.
As a material used for the cathode, a conductive material having a small work function is preferably used so that electrons can be easily injected. Examples thereof include magnesium alloys such as MgAg, aluminum alloys such as AlLi, AlCa, and AlMg, and alloys of alkali metals and alkaline earth metals such as Li, Cs, Ba, Sr, and Ca.

  The cathode film forming method and patterning method can be the same as the anode film forming method and patterning method.

4). Substrate The substrate used in the present invention supports the anode, the organic EL layer and the cathode.
When the anode has a predetermined strength, the anode itself can serve as a support, but the anode may be formed on a substrate having a predetermined strength.

The substrate may or may not have optical transparency and is appropriately selected according to the light extraction surface. When light is extracted from the substrate side, the substrate is a transparent substrate.
As the substrate, for example, a glass substrate such as soda lime glass, alkali glass, lead alkali glass, borosilicate glass, aluminosilicate glass, or silica glass, or a resin substrate that can be formed into a film can be used.
The resin used for the resin substrate is preferably one having relatively high solvent resistance and heat resistance. Specifically, fluorine resin, polyethylene, polypropylene, polyvinyl chloride, polyvinyl fluoride, polystyrene, ABS resin, polyamide, polyacetal, polyester, polycarbonate, modified polyphenylene ether, polysulfone, polyarylate, polyetherimide, polyether mon Phon, Polyamideimide, Polyimide, Polyphenylene sulfide, Liquid crystalline polyester, Polyethylene terephthalate, Polybutylene terephthalate, Polyethylene naphthalate, Polymicroxylene dimethylene terephthalate, Polyoxymethylene, Polyethersulfone, Polyetheretherketone, Polyacrylate, Acrylonitrile -Styrene resin, phenol resin, urea resin, melamine resin, unsaturated polyester resin, Poxy resin, polyurethane, silicone resin, amorphous polyolefin and the like can be mentioned. Moreover, these copolymers can also be used. Further, if necessary, a substrate having a gas barrier property that blocks gas such as moisture and oxygen may be used.

  The thickness of the substrate is appropriately selected depending on the constituent material of the substrate and the use of the organic EL element. Specifically, the thickness of the substrate is about 0.005 mm to 5 mm.

5. Other Configurations The organic EL element of the present invention may have other arbitrary constituent members in addition to the above constituent members.

  For example, when the anode is formed in a pattern on the substrate, an insulating layer may be formed so as to cover the end of the anode pattern. The insulating layer may be formed so as to define pixels. As the insulating layer, a general organic EL element can be used.

  Moreover, when using the organic EL element of this invention for a display apparatus, the TFT element may be formed on the board | substrate. As the TFT element, a common element in an organic EL element can be used.

When a full-color or multi-color display device is manufactured using the organic EL element of the present invention, a partition wall may be formed on the substrate. When the partition is formed, the cathode can be formed in a pattern without using a metal mask or the like.
As a material for the partition, a general partition material in an organic EL element can be used. For example, a photo-curable resin such as a photosensitive polyimide resin or an acrylic resin, a thermosetting resin, an inorganic material, or the like. Can be mentioned.
When the light emitting layer is formed in a pattern, the partition wall may be subjected in advance to a surface treatment that changes the surface energy (wetting property).

6). Applications The organic EL device of the present invention may be a bottom emission type in which light is extracted from the anode side or a top emission type in which light is extracted from the cathode side, and double-sided light emission in which light is extracted from both sides of the anode and cathode. It may be a mold.
The organic EL element of the present invention can be suitably used for display devices and lighting devices. The display device may be passive matrix drive or active matrix drive.

B. Manufacturing method of organic EL element The manufacturing method of the organic EL element of this invention is a manufacturing method of the organic EL element which has an organic EL layer formation process which forms an organic EL layer on an anode, Comprising: The said organic EL layer formation process is the above-mentioned. A hole injection layer forming step of forming a hole injection layer containing a polymer material on the anode by a coating method, and forming one or more polymer layers on the hole injection layer by a coating method A polymer layer forming step, and a low molecular layer forming step of forming one or more low molecular layers on the one or more polymer layers by a vacuum film forming method, and on the hole injection layer A hole transport layer forming step of forming a hole transport layer having the one or more polymer layers and the one or more low molecular layers, and a low molecular material on the hole transport layer by a vacuum film formation method. And a light emitting layer forming step of forming a light emitting layer containing a light emitting layer.

  2A to 2E are process diagrams showing an example of a method for producing an organic EL element of the present invention. First, as shown in FIG. 2A, the hole injection layer 4 is formed by applying a hole injection layer forming coating solution containing a polymer material on the substrate 2 on which the anode 3 is formed. (Hole injection layer forming step). Next, as shown in FIG. 2B, a polymer layer forming coating solution is applied on the hole injection layer 4 to form the polymer layer 5 (polymer layer forming step). Subsequently, as shown in FIG. 2C, a low molecular material is deposited on the polymer layer 5 to form the low molecular layer 6 (low molecular layer forming step). Thereby, the positive hole transport layer 11 which has the polymer layer 5 and the low molecular layer 6 is obtained (hole transport layer formation process). Next, as shown in FIG. 2D, a light emitting layer 7 is formed by depositing a low molecular material on the hole transport layer 11 (light emitting layer forming step). Next, as shown in FIG. 2E, an electron injection layer 9 is formed by depositing a low molecular material on the light emitting layer 7 (electron injection layer forming step). Thereby, the organic EL layer 12 having the hole injection layer 4, the hole transport layer 11, the light emitting layer 7 and the electron injection layer 9 is obtained. Finally, as shown in FIG. 2 (e), a cathode 10 is formed on the electron injection layer 9 (cathode formation step). In this way, the organic EL element 1 can be manufactured.

  According to the present invention, since two layers of a hole injection layer containing a polymer material and a polymer layer constituting a hole transport layer are laminated on the anode by a coating method, foreign matter, protrusions are formed on the anode surface. Even when a depression or the like is present, these foreign matters, protrusions, depressions and the like can be covered, and the occurrence of short-circuit defects can be suppressed. In addition, according to the present invention, since the hole transport layer is formed by laminating the polymer layer and the low molecular layer, functional separation is possible, and a material having excellent electron blocking property can be used for the low molecular layer. It is possible to achieve a long life. Furthermore, in the light emitting material used for the light emitting layer, the low molecular weight material has higher luminous efficiency and longer life than the polymer material, and is superior in material performance. Therefore, in the present invention, it is possible to obtain an organic EL element having excellent characteristics such as efficiency and lifetime.

  Further, in the hole transport layer in the present invention, functional separation is possible as described above, and one hole transport layer, particularly one polymer layer, has hole transport properties and electron blocking properties. In addition, since it is not necessary to use a material that can be dispersed or dissolved in a solvent that does not dissolve the hole injection layer, the material selectivity of the polymer layer and the low molecular layer is increased.

  Furthermore, since the low molecular layer is formed by the vacuum film forming method, the low molecular layer can be easily laminated on the polymer layer, and such a low molecular layer is formed between the polymer layer and the light emitting layer. Thus, it is possible to prevent holes or electrons from penetrating from the light emitting layer and to obtain a long-life organic EL element.

  Hereinafter, each process in the manufacturing method of the organic EL element of this invention is demonstrated.

1. Organic EL layer forming step The organic EL layer forming step in the present invention is a step of forming an organic EL layer on the anode, and is a positive step of forming a hole injection layer containing a polymer material on the anode by a coating method. The hole injection layer forming step, the polymer layer forming step of forming one or more polymer layers on the hole injection layer by a coating method, and the one or more polymer layers by a vacuum film formation method A hole transport layer having a low molecular layer forming step of forming one or more low molecular layers thereon, and having the one or more polymer layers and the one or more low molecular layers on the hole injection layer; A hole transport layer forming step of forming a layer, and a light emitting layer forming step of forming a light emitting layer containing a low molecular material on the hole transport layer by a vacuum film forming method.
Hereinafter, each process in the organic EL layer forming process will be described.

(1) Hole injection layer formation process The hole injection layer formation process in this invention is a process of forming the hole injection layer containing a polymeric material on an anode with the apply | coating method.
The polymer material has been described in detail in the section of the hole injection layer in the above “A. Organic EL device”, and therefore the description thereof is omitted here.

  The hole injection layer can be formed by applying a hole injection layer forming coating solution in which the above-described polymer material is dissolved or dispersed in a solvent.

  The solvent used in the hole injection layer forming coating solution is not particularly limited as long as it can dissolve or disperse the above-described polymer material, and may be appropriately selected according to the polarity of the polymer material. Selected. In the case of a highly polar polymer material, a polar solvent is used as the solvent. On the other hand, in the case of a low polar polymer material, a nonpolar solvent is used as the solvent.

  Examples of polar solvents include water, glycerin, 1-propanol, 2-propanol, 1-butanol, ethylene glycol, propylene glycol, methyl diglycol, isopropyl glycol, butyl glycol, isobutyl glycol, neopentyl glycol, hexylene glycol, Methyl propylene diglycol, propyl propylene glycol, butyl propylene glycol, diethylene glycol monobutyl ether acetate, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol ethyl methyl ether, diethylene glycol diethyl ether, ethylene glycol Solvents having a hydroxyl group such as rumonoethyl ether, ethylene glycol monobutyl ether, diacetone alcohol, N, N-dimethylformamide, N, N-dimethylacetamide, N-methylpyrrolidone, N, N′-dimethylimidazolidinone, dimethyl Examples thereof include nitrogen-containing solvents such as sulfoxide. These may be used alone or in combination of two or more. Especially, it is preferable that a polar solvent contains 1 or more types of solvents which have at least 1 or more of hydroxyl groups.

  On the other hand, examples of the nonpolar solvent include toluene, xylene, dodecylbenzene, cyclohexanone, cyclohexanol, tetralin, mesitylene, anisole, 1-methylnaphthalene, methylene chloride, tetrahydrofuran, dichloroethane, chloroform, ethyl benzoate, butyl benzoate, and the like. Is mentioned. These may be used alone or in combination of two or more. Especially, it is preferable to use 1 or more types of solvents which do not contain hetero atoms other than carbon and hydrogen for a nonpolar solvent.

  The coating method is not particularly limited as long as it is a method using a coating liquid. For example, a dip coating method, a roll coating method, a blade coating method, a spin coating method, a micro gravure coating method, a gravure coating method, a bar coating method, and the like. Examples thereof include a coating method, a wire bar coating method, a spray coating method, a casting method, an ink jet method, a flexographic printing method, an offset printing method, and a screen printing method.

  After application of the hole injection layer forming coating solution, drying is usually performed to remove the solvent remaining in the coating film.

  The hole injection layer has been described in detail in the section of the hole injection layer in the above “A. Organic EL element”, and the description thereof is omitted here.

(2) Hole transport layer forming step The hole transport layer forming step in the present invention comprises a polymer layer forming step of forming one or more polymer layers on the hole injection layer by a coating method, A low molecular layer forming step of forming one or more low molecular layers on the one or more polymer layers by a film method, and the one or more polymers on the hole injection layer. Forming a hole transport layer having a layer and one or more low-molecular layers.
Hereinafter, each step in the hole transport layer forming step will be described.

(A) Polymer layer forming step The polymer layer forming step in the present invention is a step of forming one or more polymer layers on the hole injection layer by a coating method.

The polymer layer is formed by applying a coating solution for forming a polymer layer in which the polymer material described in the section of the hole injection layer of “A. Organic EL device” is dissolved or dispersed in a solvent. Can do.
In addition, about a solvent, the apply | coating method, etc., it can be the same as that of what was described in the term of the said positive hole injection layer formation process.

  Further, when the high molecular material contained in the high molecular layer is a high molecular weight low molecular material, the low molecular material described in the above-mentioned “A. Organic EL device” in the hole injection layer section is A polymer layer can be formed by applying a polymer layer-forming coating solution dispersed or dissolved in a solvent and then increasing the molecular weight.

  When the polymer material contained in the polymer layer has a heat and / or photocurable functional group, the polymer material may be cured simultaneously with drying or after drying.

  The polymer layer has been described in detail in the section of the hole transport layer in the above “A. Organic EL device”, and therefore the description thereof is omitted here.

(B) Low molecular layer forming step The low molecular layer forming step in the present invention is a step of forming one or more low molecular layers on the one or more high molecular layers by a vacuum film forming method.

  As the vacuum film formation method, a physical vapor deposition method (PVD method) can be used, and examples thereof include a vacuum deposition method, a sputtering method, and an ion plating method. Of these, vacuum deposition is preferred. In the vacuum deposition method, since the kinetic energy of the gas substance is low, the energy given to the polymer layer is small, and a low molecular layer can be formed without damaging the polymer layer. is there. Examples of the vacuum deposition method include a resistance heating deposition method, a flash deposition method, an arc deposition method, a laser deposition method, a high frequency heating deposition method, and an electron beam deposition method.

  In addition, since it described in detail in the term of the positive hole transport layer of the said "A. organic EL element" about the low molecular layer, description here is abbreviate | omitted.

(3) Light emitting layer forming step The light emitting layer forming step in the present invention is a step of forming a light emitting layer containing a low molecular material on the hole transport layer by a vacuum film forming method.

  In addition, about the vacuum film-forming method, it can be made to be the same as that of what was described in the term of the low molecular layer formation process of the said positive hole transport layer formation process.

  In the present invention, when a full-color or multi-color display device is manufactured using an organic EL element, a plurality of types of light-emitting layers that emit different colors are formed in a pattern with a predetermined arrangement. Examples of the method for patterning the light emitting layer include a method of performing vacuum film formation by a masking method for each emission color.

  In addition, since it described in detail in the term of the light emitting layer of said "A. organic EL element" about the light emitting layer, description here is abbreviate | omitted.

(4) Electron transport layer forming step In the present invention, after the light emitting layer forming step, an electron transport layer forming step of forming an electron transport layer containing a low molecular material on the light emitting layer is performed by a vacuum film forming method. Also good.
The method for forming the electron transport layer is described in the section of the electron transport layer in the above “A. Organic EL device”, and thus the description thereof is omitted here.

(5) Electron Injection Layer Forming Step In the present invention, after the light emitting layer forming step, an electron injection layer forming step of forming an electron injection layer containing a low molecular material on the light emitting layer is performed by a vacuum film forming method. Also good. When performing the electron transport layer forming step, an electron injection layer is formed on the electron transport layer.
The method for forming the electron injection layer has been described in the section of the electron injection layer in “A. Organic EL element” above, and therefore the description thereof is omitted here.

2. Other Steps In the present invention, an anode forming step for forming an anode on the substrate can be performed before the organic EL layer forming step. The method for forming the anode is described in the section of the anode in “A. Organic EL element” above, and thus the description thereof is omitted here.
Moreover, the cathode formation process which forms a cathode on an organic EL layer can be performed after the said organic EL layer formation process. The method for forming the cathode is described in the section of the cathode in “A. Organic EL element” above, and thus the description thereof is omitted here.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

Hereinafter, the present invention will be specifically described using examples and comparative examples.
[Example 1]
First, an indium tin oxide (ITO) thin film (thickness: 150 nm) was formed on a glass substrate by a sputtering method to form an anode. The substrate on which the anode was formed was washed and subjected to UV ozone treatment. Thereafter, an aqueous solution of polyethylenedioxythiophene-polystyrene sulfonic acid (abbreviation: “PEDOT-PSS”) is applied on the ITO thin film in the air by a spin coating method and dried to form a hole injection layer (thickness: 75 nm). ) Was formed. Here, PEDOT-PSS is a highly polar polymer material.

  Next, on the hole injection layer, poly [(9,9-di- {5-pentenyl} -fluorenyl-2,7-diyl) -co- (4,4 '-(N- (4-sec -Butylphenyl)) diphenylamine)] (thermosetting TFB) solution (solvent: xylene) was applied by spin coating, and after drying, low oxygen (oxygen concentration: 0.1 ppm or less), low humidity (water vapor concentration: The polymer layer (thickness: 25 nm) constituting the hole transport layer was formed by curing in a glove box in a state of 0.1 ppm or less. Here, the thermosetting TFB is a low polarity polymer material.

Next, on the polymer layer, bis (N- (1-naphthyl-N-phenyl) -benzidine (α-NPD) (molecular weight: 588.74) (thickness), which becomes a low molecular layer constituting the hole transport layer. : 50 nm) and a green low-molecular fluorescent material (thickness: 35 nm) to be a light emitting layer in this order in a vacuum (pressure: 5 × 10 ⁻⁵ Pa) by vapor deposition by resistance heating vapor deposition. The green low molecular weight fluorescent material has no repeating unit and has a weight average molecular weight of 1000 or less.

Next, Alq3 (thickness: 30 nm), LiF (thickness: 0.5 nm), and Al (thickness: 100 nm) are formed in this order on the light emitting layer (deposited film) by the resistance heating vapor deposition method, and an electron transport layer is formed. An electron injection layer and a cathode were formed.
Subsequently, it was sealed with alkali-free glass in a low oxygen (oxygen concentration: 0.1 ppm or less) and low humidity (water vapor concentration: 0.1 ppm or less) state to obtain an organic EL element.

[Comparative Example 1]
The same process as in Example 1 was performed until the formation of the polymer layer constituting the hole transport layer. Next, a green polymer fluorescent material (solvent: xylene) was applied on the polymer layer by a spin coating method and dried to form a light emitting layer (thickness: 60 nm). In addition, the said green high molecular fluorescent material has a repeating unit, and the weight average molecular weight is 1000 or more. Next, LiF (thickness: 2 nm), Ca (thickness: 20 nm), and Al (thickness: 100 nm) were formed in this order on the light emitting layer by resistance heating vapor deposition to form an electron injection layer and a cathode.
Subsequently, it was sealed with alkali-free glass in a low oxygen (oxygen concentration: 0.1 ppm or less) and low humidity (water vapor concentration: 0.1 ppm or less) state to obtain an organic EL element.

[Comparative Example 2]
In Example 1, the organic EL element was obtained like Example 1 except not having formed the low molecular layer which comprises a positive hole transport layer.

[Evaluation]
A voltage is applied between the anode and cathode of the obtained organic EL element, and the luminance of light emitted in a direction perpendicular to the substrate plane is set to 3000 cd / m ^2. The current efficiency was measured. Further, the current was set so that the luminance was 3000 cd / m ^2, and the time (luminance half-life) during which the luminance decreased to 1500 cd / m ² when the constant current was continuously applied was measured.
As for the first embodiment, the brightness is set to the current so as to 10000 cd / m ^2, and measures the time (luminance half life) of luminance decreases to 5000 cd / m ² when continuously applied constant current The lifetime of 3000 cd / m ² was calculated as an acceleration factor of 2.
In addition, no light emitting defects such as dark spots occurred in the range where the organic EL element was observed with the naked eye.
The results are shown in Table 1.

  From Table 1, the organic EL element of Example 1 had high efficiency and long life, and was particularly excellent in life characteristics.

DESCRIPTION OF SYMBOLS 1 ... Organic EL element 2 ... Substrate 3 ... Anode 4 ... Hole injection layer 5 ... Polymer layer 6 ... Low molecular layer 7 ... Light emitting layer 8 ... Electron transport layer 9 ... Electron injection layer 10 ... Cathode 11 ... Hole transport layer 12 ... Organic EL layer

Claims (6)

The anode,
An organic electroluminescence layer having at least a hole injection layer formed on the anode, a hole transport layer formed on the hole injection layer, and a light emitting layer formed on the hole transport layer;
An organic electroluminescence device having a cathode formed on the organic electroluminescence layer,
The hole injection layer contains a polymer material;
The hole transport layer has one or more polymer layers formed on the hole injection layer and one or more low molecular layers formed on the one or more polymer layers. ,
The organic light-emitting device, wherein the light emitting layer contains a low molecular material.   Of the hole injection layer and the polymer layer formed directly on the hole injection layer, one contains a high polarity polymer material and the other contains a low polarity polymer material. The organic electroluminescent element according to claim 1.   The organic electroluminescence device according to claim 2, wherein the hole injection layer contains the high-polarity polymer material. A method for producing an organic electroluminescence element comprising an organic electroluminescence layer forming step of forming an organic electroluminescence layer on an anode,
The organic electroluminescence layer forming step,
A hole injection layer forming step of forming a hole injection layer containing a polymer material on the anode by a coating method;
A polymer layer forming step of forming one or more polymer layers on the hole injection layer by a coating method, and one or more low layers on the one or more polymer layers by a vacuum film formation method. Hole transport having a low molecular layer forming step of forming a molecular layer, and forming a hole transport layer having the one or more polymer layers and the one or more low molecular layers on the hole injection layer A layer forming step;
And a light emitting layer forming step of forming a light emitting layer containing a low molecular material on the hole transport layer by a vacuum film forming method.   Of the hole injection layer and the polymer layer formed directly on the hole injection layer, one contains a high polarity polymer material and the other contains a low polarity polymer material. The manufacturing method of the organic electroluminescent element of Claim 4.   The method for manufacturing an organic electroluminescence element according to claim 5, wherein the hole injection layer contains the high-polarity polymer material.

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