JPWO2019194209A1 - Ink composition, manufacturing method of organic electroluminescence device and organic electroluminescence device - Google Patents

Abstract

The subject of the present invention is an ink composition applied to an inkjet printing method having excellent ejection stability and member compatibility of an inkjet head, and an excellent solvent resistance of a lower layer when manufacturing an organic EL device using the ink composition. Moreover, it is to provide an organic EL element having high external quantum efficiency (EQE). The ink composition of the present invention is used for forming the organic layer A constituting the organic electroluminescence element, and at least the organic functional material constituting the organic layer A, a fluorinated solvent, and 1 atm (101.3 kPa). 25 ° C. as compared with all non-fluorine-based solvents containing a non-fluorine-based solvent having a boiling point of 99 ° C. or higher and having at least one fluorine-based solvent present in 5% by mass or more in the ink composition. It is characterized by having the lowest vapor pressure in.

Description

The present invention relates to an ink composition, a method for producing an organic electroluminescence device using the ink composition, and an organic electroluminescence device.

In recent years, organic electroluminescence devices (hereinafter abbreviated as "organic EL elements") using electroluminescence of organic materials (hereinafter abbreviated as "EL") have rapidly become widespread in various fields. This organic EL element is a thin film type completely solid element capable of emitting light at a low voltage of about several V to several tens of V, and has many excellent features such as high brightness, high emission efficiency, thinness, and light weight. Have.

The organic EL element injects electrons and holes into the light emitting layer from the electron injection electrode and the hole injection electrode, respectively, and combines the injected electrons and holes in the light emitting layer to bring the organic material into an excited state. , This organic material emits light when it returns from the excited state to the ground state, and has the advantage that it can be driven with a low voltage. Taking advantage of the fact that it emits light on a surface, its application fields are being energetically studied as a surface light emitting body such as a display device, a display, and an illumination light source as a thin and flexible lighting application.

Conventionally, as a method for manufacturing an organic EL element, a method of manufacturing by a dry process using a chemical vapor deposition method, a vacuum vapor deposition method, or the like is widely known, but most of these dry processes are large-scale such as a vacuum device. Since it requires equipment, it has a problem that the cost increases and it is difficult to manufacture a large-area organic EL element due to the limitation of the device.

In response to the above problems, as a method for manufacturing an organic EL element, a coating method that saves energy, increases the area, reduces the weight and thickness, improves the forming accuracy, and enables high productivity, for example, an offset printing method and a gravure printing method. , "Printed Electronics" that forms various organic functional layers (hereinafter, also simply referred to as "organic layers") constituting an organic EL element by a printing method using a wet process such as a screen printing method or an inkjet printing method. Is being actively researched.

However, when each organic functional layer is to be laminated by a wet process, the elution of the already formed lower layer component becomes a problem. When the lower layer components are eluted, not only the merit of stacking the organic functional layers is lost, but also the organic EL element is short-circuited due to the reduction of film thickness uniformity, and the deterioration is accelerated due to the concentration of the electric field. To do.

As a method for dealing with such a problem, when each layer constituting the organic EL element is laminated, for example, when an organic layer to be an upper layer is laminated on a predetermined organic layer formed on a substrate, a lower layer is configured. A method of applying the upper layer using a solvent in which the material is difficult to dissolve is known. For example, usually, the light emitting layer constituting the organic EL element is easily dissolved in a non-polar solvent such as toluene and hardly dissolved in a polar solvent. Therefore, for example, when the electron transport layer corresponding to the upper layer is laminated, the polarity of alcohol or the like is used. A method of applying with a solvent has been proposed.

As a method for forming an organic layer of an organic EL element using a wet process, for example, in Patent Document 1, when forming two organic layers, one organic layer is formed with a solvent containing a fluorine-containing compound. A method of coating and coating the other one layer with a solvent containing no fluorine-containing compound is disclosed.

Further, Patent Document 2 discloses a method for producing an organic EL device by applying a composition containing an organic material and a fluorinated alcohol on a lower layer and then evaporating and removing the fluorinated alcohol from the formed coating film. ing.

On the other hand, as a method for forming an electron transport layer using a wet process, the method described in Patent Document 3 can be mentioned. In the method described in Patent Document 3, there is an example of an organic EL device in which a phosphine oxide derivative, which is an electron transport material that is soluble in an alcohol solvent and acts as a chelate ligand for a metal, is coated together with a metal complex. It is shown. However, only an example in which a polymer is used for the lower layer material is described, and it is laminated on a constituent layer formed of a low molecular weight compound which is indispensable for constructing a high-purity and highly durable element. It cannot be said that the technology is sufficient. Further, when combined with an electron transporting material having a higher electron transporting property, most of such electron transporting materials are insoluble in alcohol, and the selection range of the material is restricted.

That is, there has been a need for a wet process film forming technique capable of dissolving an electron transporting material and further producing an element having high external quantum efficiency (EQE) without elution of lower layer components.

In response to the above problem, in Patent Document 4, when an electron transport layer is formed on a plurality of organic layers of an organic EL element, for example, a light emitting layer of a lower layer by using a wet process, electrons are used as a coating liquid for forming an electron transport layer. A method is disclosed in which a transportable compound or the like is dissolved in a non-fluorinated alcohol solvent, a coating liquid having a structure containing the fluorinated alcohol solvent is prepared, and the coating liquid is laminated by a batch method using a spin coating method.

On the other hand, as a wet process, a method for manufacturing an organic EL element using an inkjet printing method is capable of obtaining a high-definition organic EL element having an arbitrary pattern by a simple method that does not require large equipment. Attention has been paid.

However, when an organic layer is formed by applying an inkjet printing method as a wet process using a composition containing a fluorine-based solvent as disclosed in each of the above patent documents, the fluorine-based solvent is used as the inkjet head. It is difficult to secure long-term injection stability because the members constituting the above are swollen. In addition, since the solvent used in the spin coating method has a low boiling point and a high vapor pressure, if it is applied to the inkjet printing method as it is, the solvent will evaporate and scatter immediately, causing a problem of nozzle clogging. there were.

In response to the above problem, by using a non-fluorine-based solvent in combination as the composition of the ink composition, the solvent resistance of the constituent layer at the time of manufacturing the organic EL element and the influence of the solvent of the constituent material of the inkjet head can be prevented to some extent, but on the other hand, on the other hand, The problem of reduced solubility in the materials that make up the ink composition arises. In such a case, it was found that when the solvent having low solubility of the material remained on the coating film until the end, the coating film became white.

Japanese Unexamined Patent Publication No. 2002-216965 Japanese Unexamined Patent Publication No. 2004-265672 Japanese Unexamined Patent Publication No. 2010-278376 Japanese Unexamined Patent Publication No. 2014-44972

The present invention has been made in view of the above problems, and the problem to be solved is to use an ink composition applied to an inkjet printing method having excellent injection stability and member compatibility in an inkjet head, and the ink composition. It is an object of the present invention to provide a method for producing an organic EL element, which is excellent in solvent resistance to a lower layer during production of the organic EL element and can obtain an organic EL element having high external quantum efficiency (EQE).

The above object of the present invention is solved by the following means.

1. 1. An ink composition for inkjet used for forming an organic layer A constituting an organic electroluminescence element.
It contains at least an organic functional material forming the organic layer A, at least one fluorine-based solvent, and a non-fluorine-based solvent having a boiling point of 99 ° C. or higher at 1 atm (101.3 kPa). ,
An ink composition, wherein the at least one fluorine-based solvent has the lowest vapor pressure at 25 ° C. as compared with all non-fluorine-based solvents in which 5% by mass or more is present in the ink composition.

2. The ink composition according to Item 1, wherein the fluorinated solvent contains two or more kinds of fluorinated solvents having different vapor pressures at 25 ° C.

3. 3. It contains at least two types of fluorine-based solvent A1 and fluorine-based solvent A2, and non-fluorine-based solvent B, and the order of the vapor pressures of each of the above solvents at 25 ° C. satisfies the condition specified by the following relational expression 1. The ink composition according to the first or second paragraph, which is characteristic.
(Relational formula 1)
Vapor pressure Fluorine solvent A2 <Non-fluorine solvent B <Fluorine solvent A1

4. The ink composition according to Item 3, wherein the difference in boiling points between the two types of fluorine-based solvent A1 and the fluorine-based solvent A2 is 20 ° C. or higher at 1 atm (101.3 kPa).

5. The ink composition according to any one of items 1 to 4, wherein the total amount of the fluorine-based solvent with respect to the total amount of the ink composition is 51% by mass or more.

6. The ink composition according to any one of items 1 to 5, wherein the organic functional material constituting the organic layer A is an electron transport material or an electron injection material.

7. The ink composition according to item 6, wherein the organic functional material constituting the organic layer A is an electron transporting material.

8. A method for manufacturing an organic electroluminescence device having an organic layer.
An organic electroluminescence device, which comprises forming at least one organic layer A using the ink composition according to any one of items 1 to 7 by using an inkjet printing method. Production method.

9. The organic electroluminescence element according to Item 8, wherein the organic layer A is formed by using the ink composition on the organic layer B containing an organic compound having a molecular weight in the range of 700 to 2000. Production method.

10. An organic electroluminescence device having an organic layer formed by using the ink composition according to any one of items 1 to 7.

INDUSTRIAL APPLICABILITY According to the present invention, an ink composition applied to an inkjet printing method having excellent ejection stability and member compatibility of an inkjet head, and an ink composition having excellent solvent resistance to an lower layer during production of an organic EL device using the ink composition and external. It is possible to provide an organic EL device having high quantum efficiency (EQE).

The technical features of the method for producing an organic EL device using the ink composition of the present invention and the mechanism for expressing the effects are presumed as follows.

When an attempt is made to produce an organic EL device by an inkjet printing method using a fluorine-based solvent and a non-fluorine-based solvent as described above, the present inventors have formed an organic layer, for example, an electron transport layer on the light emitting layer. It was found that when applied, the coating film became white and uneven emission may occur. In response to such problems, the coating solvent when these organic EL elements are manufactured by the inkjet printing method has been repeatedly studied, and when another organic functional layer is laminated and coated on the organic functional layer, for example, on the organic layer B. When the organic layer A is applied, the ink composition used for forming the organic layer A is an organic functional material constituting the organic layer A, a fluorine-based solvent, and a boiling point of 99 ° C. or higher at 1 atm (101.3 kPa). A configuration in which the vapor pressure at 25 ° C. is the lowest as compared with all non-fluorine-based solvents containing a certain non-fluorine-based solvent and in which at least one of the fluorine-based solvents is present in an ink composition in an amount of 5% by mass or more. By doing so, it has been found that a transparent and even organic functional layer film can be formed even when applied by an inkjet printing method.

Although the details of the reason why the above effect is exhibited by using a fluorine-based solvent in combination as the solvent constituting the ink composition are not clear, it is considered as follows.

The fluorine-based solvent becomes a highly polar solvent due to the electronegativity of fluorine, and easily dissolves the material. On the other hand, the fluorine atom part does not easily interact with other substances. Therefore, the fluorine-based solvent has a moderate interaction with the material of the light emitting layer (organic layer A) as the lower layer, and the organic layer A, which is another organic functional layer, is placed on the light emitting layer in an ink composition containing the fluorine-based solvent. When inkjet printing is performed using the above, it is considered that the lower layer is not easily attacked by the fluorine-based solvent and at the same time the coatability (wetability) is good.

Therefore, it is presumed that the fluorine-based solvent can apply the organic layer evenly without eluting the underlying organic layer material and without mixing or disturbing the layer interface.

Further, the underlying organic layer material is preferably a low molecular weight material (for example, having a molecular weight of 500 or more), but among them, when the molecular weight is 700 or more, it is difficult to elute into a non-fluorinated solvent, which is preferable. Further, it is preferable that the molecular weight is 2000 or less from the viewpoint of obtaining excellent organic EL device performance.

Schematic cross-sectional view showing an example of the configuration of an organic electroluminescence device Schematic perspective view showing an example of the structure of an inkjet head applicable to an inkjet printing method. Schematic perspective view showing an example of the structure of an inkjet head applicable to an inkjet printing method. Bottom view showing an example of the structure of an inkjet head applicable to an inkjet printing method

The ink composition of the present invention is an ink composition for inkjet used for forming the organic layer A constituting the organic electroluminescence element, and at least the organic functional material constituting the organic layer A and a fluorine-based solvent. And all non-fluorinated solvents having a boiling point of 99 ° C. or higher at 1 atm (101.3 kPa) and in which at least one of the fluorine-based solvents is present in an ink composition in an amount of 5% by mass or more. It is characterized by having the lowest vapor pressure at 25 ° C. as compared with a fluorinated solvent. This feature is a technical feature common to the inventions according to the following embodiments.

As an embodiment of the present invention, from the viewpoint that the effect intended by the present invention can be more exhibited, the ink composition contains two or more kinds of fluorine-based solvents having different vapor pressures at 25 ° C. as the fluorine-based solvent. Furthermore, it contains at least two kinds of fluorine-based solvent A1 and fluorine-based solvent A2, and a non-fluorine-based solvent B having a boiling point of 99 ° C. or higher, and the order of the vapor pressures of each of the above solvents at 25 ° C. is as follows. A fluorine-based solvent having good wettability by having a configuration that satisfies the conditions specified by the relational expression 1 and setting the difference in boiling point between the two types of fluorine-based solvent A1 and the fluorine-based solvent A2 to 20 ° C. or more. A1 evaporates first to form a uniform film to some extent, then the non-fluorine-based solvent evaporates, and finally the fluorine-based solvent A2, which has high material solubility, evaporates. It is preferable in that a coating film can be formed without a solvent.

Further, when the total amount of the fluorine-based solvent with respect to the total amount of the solvent of the ink composition is 51% by mass or more, the solubility in the material constituting the organic functional layer is improved, and the lower layer is composed of a low molecular weight. For example, it is preferable in that an electron transport layer or the like can be stably formed on the light emitting layer.

That is, in the method for producing an organic EL element using the inkjet printing method, the functional material and the present invention are placed on the organic layer B containing an organic compound having a molecular weight in the range of 700 to 2000, which constitutes the organic EL element. An organic layer composed of a low molecular weight material already formed in the lower layer is formed by injecting an ink composition containing a fluorine-based solvent and a non-fluorine-based solvent having the constitution specified in 1. It is preferable in that the solute of B and the like are not dissolved, mixing and disorder do not occur at the layer interface, rinse resistance is improved, and an organic functional layer group having a laminated structure can be stably formed.

In the method for forming the organic functional layer group as described above, the organic layer B is a light emitting layer, and the organic layer A is an electron transporting layer or an electron injecting layer containing an electron transporting material or an electron injecting material as an organic functional material. Further, it is preferable that the electron transport layer contains an electron transport material.

Hereinafter, the components of the present invention and the embodiments for carrying out the present invention will be described in detail with reference to the drawings. In the present application, "~" representing a numerical range is used to mean that the numerical values described before and after the numerical range are included as the lower limit value and the upper limit value.

<< Ink composition >>
The ink composition of the present invention is used for forming at least an organic layer constituting an organic EL by an inkjet printing method, and has an organic functional material, a fluorine-based solvent, and a boiling point of 99 ° C. or higher at 1 atm (101.3 kPa) or more. It is characterized in that it contains a non-fluorine-based solvent, and at least one kind of fluorine-based solvent has the lowest vapor pressure (kPa) at 25 ° C. among all the solvents contained in the solvent. ..

Further, as another form of the ink composition of the present invention, at least an organic functional material constituting an organic layer, two kinds of fluorine-based solvent A1 and a fluorine-based solvent A2, and a non-fluorinated solvent having a boiling point of 99 ° C. or higher are not used. It is preferable that the fluorinated solvent B is contained and the relationship of the vapor pressure (kPa) of each solvent at 25 ° C. satisfies the condition specified by the following relational expression 1.
(Relational formula 1)
Vapor pressure Fluorine solvent A2 <Non-fluorine solvent B <Fluorine solvent A1

The vapor pressure (kPa) of each solvent according to the present invention at 25 ° C. can be determined according to the following method. For example, a lead method based on JIS K2258-1: 2009, a triple expansion method based on JIS K2258-2: 2009, and the like can be mentioned. Further, a static method, a boiling point method, an isoteniscope, a gas flow method, and a DSC method, which are known as general methods for measuring vapor pressure, can also be applied. Furthermore, it is also possible to utilize the vapor pressure data described in publicly known documents, for example, "New Edition Solvent Pocket Book" (edited by the Church of Synthetic Organic Chemistry, Ohmsha).

Next, each solvent constituting the ink composition of the present invention will be described. However, the details of each organic functional material constituting the organic layer will be described according to the configuration of the organic EL element. Further, in the following description, the boiling point of the non-fluorinated solvent B is defined as the boiling point at 1 atm (101.3 kPa).

[Fluorine solvent]
In the ink composition of the present invention, 1) a composition of a fluorine-based solvent and a non-fluorine-based solvent having a boiling point of 99 ° C. or higher, or two types of fluorine-based solvent A1 and a fluorine-based solvent A2 having a boiling point of 99 ° C. or higher. The non-fluorine-based solvent B is characterized in that the vapor pressure of at least one kind of fluorine-based solvent at 25 ° C. is the lowest vapor pressure among the solvents.

The fluorine-based solvent applicable to the present invention is not particularly limited as long as it has a fluorine atom in its structure.

Examples thereof include fluorine-containing hydrocarbons, fluorine-containing alcohols, fluorine-containing aromatic compounds, fluorine-containing ethers, fluorine-containing ketones, fluorine-containing esters, fluorine-containing amides, and fluorine-containing carboxylic acids.

In the present invention, among these, the objective effect of the present invention is excellent in injection stability and member compatibility with the inkjet head, and rinsing resistance (solvent resistance) to the lower layer at the time of manufacturing the organic EL element using the ink composition. It is preferable to use a fluorine-containing alcohol as the fluorine-based solvent from the viewpoint of excellent properties).

Examples of the fluorine-based solvent applicable to the present invention include compounds having a structure represented by the following general formula (a). When two kinds of fluorine-based solvents are used in the ink composition of the present invention, it is preferable to use a combination of fluorine-based solvents having different boiling points of 20 ° C. or more.

General formula (a)
A-CH ₂ OH
In the above general formula (a), A represents CF ₃ or CHF ₂ (CF ₂ ) _n , and n represents an integer of 1 to 5. n is preferably 1 to 3, and more preferably 1.

As the fluorine-based solvent according to the present invention, a fluorine-based solvent having a structure represented by the following general formula (b) or general formula (c) is further preferable.

In the general formula (b) and the general formula (c), A, B, and D represent CH _3-x F _x or CH _3-x F _x (CH _2-y F _y ) _n , respectively, and x is 1. ~ 3, y represents 1-2, n represents 0 or 1.

Specific examples of the fluorine-based solvent according to the present invention include the compounds shown below.

a) 2,2,3,3-tetrafluoro-1-propanol (abbreviation: TFPO, boiling point: 109 ° C., vapor pressure: 2.53 kPa),
b) 2,2,3,3,3-pentafluoro-1-propanol (abbreviation: PFPO, boiling point: 81 ° C., vapor pressure: 5.45 kPa),
c) 2-Trifluoromethyl-2-propanol (abbreviation: TFMPO, boiling point: 83 ° C., vapor pressure: 11.47 kPa (calculated value))
d) 2,2,3,4,5,4-hexafluoro-1-butanol (abbreviation: HFBO, boiling point: 114 ° C., vapor pressure: 2.63 kPa (calculated value)),
e) 2,2,3,3,4,5,5-octafluoro-1-pentanol (abbreviation: OFPO, boiling point: 142 ° C., vapor pressure: 0.51 kPa),
f) 1,1,1,3,3,3-hexafluoro-2-propanol (abbreviation: HxFPO, boiling point: 58 ° C., vapor pressure: 20.84 kPa (calculated value)),
g) 2,3-Difluorobenzyl alcohol (abbreviation: DFSA, boiling point: 88 ° C),
h) 2,2,2-Trifluoroethanol (abbreviation: TFEO, boiling point: 78 ° C., vapor pressure: 7.09 kPa),
i) 1,3-Difluoropropan-2-ol (abbreviation: DFSO, boiling point: 55 ° C., vapor pressure: 4.52 kPa),
j) 1,1,1-trifluoro-2-propanol (abbreviation: TrF2PO, boiling point: 82 ° C.),
k) 3,3,3-trifluoro-1-propanol (abbreviation: TrF1PO, boiling point: 100 ° C., vapor pressure: 5.14 kPa (calculated value)),
l) 2,2,3,3,4,5,4-heptafluoro-1-butanol (abbreviation: HpFBO, boiling point: 97 ° C., vapor pressure: 4.56 kPa (calculated value)),
m) 3,3,4,5,5,5-heptafluoro-2-pentanol (abbreviation: HpFPO, boiling point: 102 ° C., vapor pressure: 4.08 kPa (calculated value)),
n) 1H, 1H-pentadecafluoro-1-octanol (abbreviation: PDFOO, boiling point: 163 ° C., vapor pressure: 0.32 kPa (calculated value)),
p) 1H, 1H, 2H, 2H-tridecafluoro-1-n-octanol (abbreviation: TDFOO, boiling point: 88-95 ° C., vapor pressure: 3.72 kPa),
q) 1H, 1H, 7H-dodecafluoro-1-heptanol (abbreviation: DFHO, boiling point: 170 ° C., vapor pressure: 0.14 kPa (calculated value)),
r) 1H, 1H, 9H-hexadecafluoro-1-nonanol (abbreviation: HDFNO, boiling point: 156 ° C., vapor pressure: 2.66 kPa),
s) 1H, 1H, 2H, 2H-heptadecafluoro-1-decanol (abbreviation: HDFDO, boiling point: 115 ° C., vapor pressure: 2.66 kPa),
t) 2-Perfluorohexyl ethanol (abbreviation: PFHEO, boiling point: 75-80 ° C, vapor pressure: 1.86 kPa),
u) 2-Perfluorobutylethanol (abbreviation: PFBEO, boiling point: 140 to 143 ° C.), vapor pressure: 0.38 kPa (calculated value),
And so on.

In the ink composition of the present invention, it is preferable to use two kinds of fluorine-based solvent A1 and fluorine-based solvent A2 in combination and set the relationship of vapor pressure to fluorine-based solvent A2 <non-fluorine-based solvent B <fluorine-based solvent A1. Further, a combination in which the difference in boiling point between the fluorinated solvent A1 and the fluorinated solvent A2 is 20 ° C. or higher is preferable. Specific combinations include 2,2,3,3-tetrafluoro-1-propanol (boiling point: 109 ° C., vapor pressure: 2.53 kPa, abbreviation: TFPO) and 2,2,3,3,4,4. , 5,5-Octafluoro-1-pentanol (boiling point: 142 ° C., vapor pressure: 0.51 kPa, abbreviation: OFPO) is preferably used in combination.

These fluorine-based solvents can be easily obtained as commercial products.

In the ink composition of the present invention, the ratio of the fluorine-based solvent according to the present invention to the total amount of the ink composition is not particularly limited and may be in the range of 30 to 95% by mass, but is preferably 51. It is in the range of ~ 95% by mass, more preferably in the range of 70 to 90% by mass.

[Non-fluorine solvent]
The ink composition of the present invention is characterized in that a non-fluorine solvent having a boiling point of 99 ° C. or higher at 1 atm (101.3 kPa) is used in combination with the fluorine solvent, and at least one non-fluorine solvent is used. In a system containing two types of fluorine-based solvents (fluorine-based solvent A1 and fluorine-based solvent A2), the vapor pressure (kPa) of each solvent is higher than that of the fluorine-based solvent. , It is preferable that the condition specified by the relational expression 1 is satisfied.

The non-fluorine-based solvent applicable to the ink composition of the present invention is not particularly limited as long as it is an organic solvent having a boiling point of 99 ° C. or higher at 1 atm (101.3 kPa) containing no fluorine atom. Conventionally known organic solvents such as hydrogens, alcohols, ethers and acetals, ketones and aldehydes, esters, polyhydric alcohol derivatives and the like can be appropriately selected.

The following is an example of a typical non-fluorinated solvent having a boiling point of 99 ° C. or higher at 1 atm (101.3 kPa), but the present invention is not limited to these exemplified organic solvents.

(1: Hydrocarbons)
a) o-xylene (boiling point: 144 ° C., vapor pressure: 0.88 kPa)
b) p-xylene (boiling point: 138 ° C., vapor pressure: 0.87 kPa)
c) Mesitylene (boiling point: 165 ° C., vapor pressure: 0.32 kPa (calculated value))
d) Methylcyclohexane (boiling point: 101 ° C., vapor pressure: 4.92 kPa)
(2: Alcohol)
a) n-amyl alcohol (boiling point: 138 ° C., vapor pressure: 0.87 kPa)
b) s-amyl alcohol (boiling point: 119 ° C., vapor pressure: 1.55 kPa)
c) t-amyl alcohol (boiling point: 102 ° C., vapor pressure: 1.46 kPa)
d) 3-Methyl-1-butanol (boiling point: 131 ° C., vapor pressure: 0.31 kPa)
e) Isobutyl alcohol (boiling point: 108 ° C., vapor pressure: 1.20 kPa)
f) n-octanol (boiling point: 195 ° C., vapor pressure: 0.02 kPa)
g) 1-butanol (boiling point: 118 ° C., vapor pressure: 0.88 kPa)
h) s-butanol (boiling point: 99.5 ° C., vapor pressure: 2.66 kPa)
i) 3-Methyl-2-butanol (boiling point: 112 ° C., vapor pressure: 1.29 kPa)
j) 1-Methoxy-2-butanol (boiling point: 135 ° C.)
k) 1-methoxy-2-propanol (abbreviation: MeOPrO, boiling point: 120 ° C., vapor pressure: 0.67 kPa)
l) 3-Methoxy-1-butanol (boiling point: 161 ° C., vapor pressure: 0.16 kPa (calculated value))
m) n-Hexanol (boiling point: 157 ° C., vapor pressure: 0.13 kPa)
n) 2-Hexanol (boiling point: 139 ° C., vapor pressure: 0.35 kPa)
o) 2-Methyl-1-propanol (boiling point: 108 ° C., vapor pressure: 1.53 kPa (calculated value))
p) 3-Pentanol (boiling point: 116 ° C., vapor pressure: 1.17 kPa)
(3: Ethers and acetals)
a) Diethyl acetal (boiling point: 108 ° C., vapor pressure: 1.33 kPa)
(4: Ketones and aldehydes)
a) Diethylketone (boiling point: 102 ° C., vapor pressure: 3.99 kPa)
b) Cyclopentanone (boiling point: 130 ° C., vapor pressure: 1.38 kPa (calculated value))
c) Cyclohexanone (boiling point: 156 ° C., vapor pressure: 0.67 kPa)
d) Methyl isobutyl ketone (boiling point: 116 ° C., vapor pressure: 2.11 kPa)
e) Acetylacetone (boiling point: 140 ° C., vapor pressure: 0.80 kPa)
f) Methyl-n-propyl ketone (boiling point: 103 ° C., vapor pressure: 3.70 kPa)
(5: Esters)
a) Butyl formate (boiling point: 107 ° C., vapor pressure: 3.06 kPa)
b) Amyl acetate (boiling point: 149 ° C., vapor pressure: 1.29 kPa)
c) Allyl acetate (boiling point: 104 ° C., vapor pressure: 6.12 kPa)
d) Butyl acetate (boiling point: 126 ° C., vapor pressure: 1.60 kPa)
e) Propyl acetate (boiling point 102 ° C., vapor pressure: 4.52 kPa)
f) Diethyl carbonate (boiling point: 126 ° C., vapor pressure: 7.18 kPa)
g) Ethyl propionate (boiling point: 99.1 ° C., vapor pressure: 1.11 kPa)
h) Butyl propionate (boiling point: 147 ° C., vapor pressure: 0.86 kPa)
(6: Polyhydric alcohol derivative)
a) Ethylene glycol (abbreviation: EG, boiling point: 197 ° C, vapor pressure: 0.09 kPa)
b) Ethylene glycol diethyl ether (abbreviation: EGDEE, boiling point: 121 ° C., vapor pressure: 1.25 kPa)
c) Ethylene glycol monoethyl ether (abbreviation: EGMEE, boiling point: 136 ° C., vapor pressure: 0.65 kPa (calculated value))
d) Ethylene glycol monoethyl ether acetate (abbreviation: EGMEEAc, boiling point: 156 ° C., vapor pressure: 0.30 kPa (calculated value))
e) Ethylene glycol monobutyl ether (abbreviation: EGMBE, boiling point: 171 ° C., vapor pressure: 1.25 kPa)
f) Ethylene glycol monomethyl ether (abbreviation: EGMME, boiling point: 124 ° C., vapor pressure: 0.80 kPa)
g) Ethylene glycol monomethyl ether acetate (abbreviation: EGMMEAc, boiling point: 145 ° C., vapor pressure: 0.40 kPa)
h) Diethylene glycol dimethyl ether (abbreviation: DEGDME, boiling point: 162 ° C., vapor pressure: 0.40 kPa)
i) Propylene glycol (abbreviation: PG, boiling point: 187 ° C., vapor pressure: 0.01 kPa (calculated value))
j) Propylene glycol monoethyl ether (abbreviation: PGMEE, boiling point: 133 ° C., vapor pressure: 0.53 kPa)
k) Propylene glycol monomethyl ether (abbreviation: PGMME, boiling point: 121 ° C., vapor pressure: 1.45 kPa)
l) Propylene glycol monomethyl ether acetate (abbreviation: PGMMEAc, boiling point: 146 ° C., vapor pressure: 0.49 kPa)
In addition, carboxylic acids, phenols, nitrogen-containing compounds, sulfur-containing compounds and the like having a boiling point of 99 ° C. or higher can be mentioned.

In the ink composition of the present invention, the ratio of the non-fluorine-based solvent according to the present invention to the total amount of the ink composition is not particularly limited and is preferably in the range of 5 to 70% by mass, more preferably. It is in the range of 5 to 45% by mass, more preferably in the range of 10 to 30% by mass.

[Organic functional materials]
In the present invention, a fluorine-based solvent and a non-fluorine-based solvent having a boiling point of 99 ° C. or higher are used to dissolve an organic functional material for forming an organic functional layer (organic layer A) constituting an organic EL device. To form an ink composition.

The organic functional material referred to in the present invention is a material for forming an organic functional layer of an organic EL element, for example, a phosphorescent compound for forming a light emitting layer, a fluorescent light emitting compound, or a host compound. Etc., hole injection material for forming a hole injection layer, electron injection material for forming an electron injection layer, hole transport material for forming a hole transport layer, electron transport for forming an electron transport layer, etc. Examples thereof include materials and materials for forming a hole blocking layer and an electron blocking layer. Details of each of these organic functional materials will be described later.

In the present invention, in that the objective effect of the present invention can be more exhibited, the organic EL element is injected onto the organic layer B containing an organic compound having a molecular weight in the range of 700 to 2000. It is preferable to form the organic layer A using an ink composition having the constitution specified in the present invention. For example, an electron transport layer may be formed on a light emitting layer containing an organic compound having a molecular weight in the range of 700 to 2000 by using an ink composition containing an electron transport material with the solvent composition specified in the present invention. , Especially preferable.

[Ink composition: other additives]
In the ink composition of the present invention, in addition to the constituent materials specified in the present invention, ejection stability, printhead compatibility, storage stability, storage stability, and other factors are not impaired. Various known additives such as viscosity modifiers, surface tension modifiers, specific resistance modifiers, film-forming agents, dispersants, surfactants, ultraviolet absorbers, antioxidants, etc., depending on the purpose of improving various performances. An anti-fading agent, an anti-bacterial agent, an anti-rust agent and the like can be appropriately selected and used.

<< Organic EL element >>
The present invention is characterized in that, in the production of an organic EL device having an organic layer, at least one organic layer is formed by using the ink composition of the present invention by using an inkjet head.

[Overall configuration of organic EL element]
First, the basic configuration of the organic EL element will be described.

FIG. 1 shows a schematic cross-sectional view of a typical configuration of the organic EL device of the present invention.

As shown in FIG. 1, each constituent member of the organic EL element 1 is provided on the base material 2, and an organic functional layer unit configured by using the first electrode 3, an organic material, or the like from the base material 2 side. The U and the second electrode 9 are laminated in this order. A take-out electrode 10 is provided at the end of the first electrode 3. The first electrode 3 and the external power supply (not shown) are electrically connected via the take-out electrode 10. The organic EL element 1 shown in FIG. 1 is configured to take out the generated light emitting light L from at least the base material 2 side.

Further, the structure of the organic EL element 1 is not particularly limited, and may be a general layer structure. The details of the specific configuration of the organic EL element 1 will be described with reference to FIG.

In the specific configuration shown in FIG. 1, the first electrode 3 functions as an anode (that is, an anode), and the second electrode 9 functions as a cathode (that is, a cathode). In this case, for example, in the organic functional layer unit U, the hole injection layer 4 / hole transport layer 5 / light emitting layer 6 / electron transport layer 7 / electron injection layer 8 are laminated in this order from the first electrode 3 side which is the anode. The configuration is exemplified, but among them, it is an indispensable constituent requirement to have a light emitting layer 6 constructed by using at least an organic material. The hole injection layer 4 and the hole transport layer 5 may be provided as the hole transport injection layer. Similarly, the electron transport layer 7 and the electron injection layer 8 may be provided as an electron transport injection layer. Further, among these organic functional layer units U, for example, the electron injection layer 8 may be made of an inorganic material.

Further, in the organic functional layer unit U, in addition to these layers, a hole blocking layer, an electron blocking layer, and the like may be laminated as needed. Further, the light emitting layer 6 may have a plurality of color light emitting layers for generating light emitted in each wavelength region, and each of these color light emitting layers may be laminated via a non-light emitting intermediate layer. The intermediate layer may be provided with a function as a hole blocking layer or an electron blocking layer. Further, the second electrode 9 which is a cathode may also have a laminated structure as required. In such a configuration, only the portion where the organic functional layer unit U is sandwiched between the first electrode 3 and the second electrode 9 becomes the light emitting region LA in the organic EL element 1.

The organic EL element 1 having the above configuration is provided on the base material 2 via a sealing adhesive 12 for the purpose of preventing deterioration of the organic functional layer unit U configured by using an organic material or the like. It is sealed with the sealing base material 13. Further, the first electrode 3 and its take-out electrode 10 and the terminal portion of the second electrode 9 and its take-out electrode 11 are bonded to each other on the base material 2 while being insulated from each other by the organic functional layer unit U. It is provided in a state of being exposed from the agent 12.

[Other layer structure of organic EL element]
Regarding the configuration of the organic EL element EL applicable to the present invention, in addition to the configuration shown in FIG. 1, the configuration shown below can be mentioned. The numbers in parentheses correspond to the symbols of each component of the organic EL element shown in FIG.

(I) On the base material 2, the first electrode 3 (anode) / organic functional layer unit (light emitting layer 6 / electron transport layer 7) / second electrode 9 (cathode) / sealing adhesive 12 / sealing member A configuration in which 13 are laminated,
(Ii) First electrode 3 (anode) / organic functional layer unit (hole transport layer 5 / light emitting layer 6 / electron transport layer 7) / second electrode 9 (cathode) / sealing adhesive on the base material 2. A configuration in which the agent 12 / sealing member 13 is laminated,
(Iii) On the base material 2, the first electrode 3 (anode) / organic functional layer unit (hole transport layer 5 / light emitting layer 6 / hole blocking layer / electron transport layer 7) / second electrode 9 (cathode) / A configuration in which the sealing adhesive 12 / sealing member 13 is laminated,
(Iv) On the base material 2, the first electrode 3 (anode) / organic functional layer unit (hole transport layer 5 / light emitting layer 6 / hole blocking layer / electron transport layer 7 / cathode buffer layer) / second electrode 9 (cathode) / sealing adhesive 12 / sealing member 13 laminated,
(V) First electrode 3 (anode) / organic functional layer unit (anode buffer layer / hole transport layer 5 / light emitting layer 6 / hole blocking layer / electron transport layer 7 / cathode buffer layer) on the base material 2. / Second electrode 9 (cathode) / Sealing adhesive 12 / Sealing member 13 laminated,
And so on.

For other outlines of the configuration of the organic EL element applicable to the present invention, for example, Japanese Patent Application Laid-Open No. 2013-157634, Japanese Patent Application Laid-Open No. 2013-168552, Japanese Patent Application Laid-Open No. 2013-177361, Japanese Patent Application Laid-Open No. 2013-187211. Japanese Patent Application Laid-Open No. 2013-191644, Japanese Patent Application Laid-Open No. 2013-191804, Japanese Patent Application Laid-Open No. 2013-225678, Japanese Patent Application Laid-Open No. 2013-235994, Japanese Patent Application Laid-Open No. 2013-243234, Japanese Patent Application Laid-Open No. 2013-243236, JP-A-2013-242366, JP-A-2013-243371, JP-A-2013-245179, JP-A-2014-003249, JP-A-2014-003299, JP-A-2014-013910, JP-A-2014. Examples thereof include configurations described in Japanese Patent Application Laid-Open No. 2014-017493, Japanese Patent Application Laid-Open No. 2014-017494, and the like.

Specific examples of the tandem type organic EL element include, for example, US Pat. No. 6,337,492, US Pat. No. 7,420,203, US Pat. No. 7,473,923, US Pat. No. 6,872,472, US Pat. No. 6107734, US Pat. No. 6,337,492, Japanese Patent Application Laid-Open No. 2006-228712, Japanese Patent Application Laid-Open No. 2006-24791, Japanese Patent Application Laid-Open No. 2006-49393, Japanese Patent Application Laid-Open No. 2006-49394, Japanese Patent Application Laid-Open No. 2006- 49396, 2011-96679, 2005-340187, 47112424, 349661, 3884564, 4213169, 2010-192719 Japanese Patent Application Laid-Open No. 2009-07629, Japanese Patent Application Laid-Open No. 2008-0784414, Japanese Patent Application Laid-Open No. 2007-059848, Japanese Patent Application Laid-Open No. 2003-272860, Japanese Patent Application Laid-Open No. 2003-045676, International Publication No. 2005/009087, Examples thereof include the element configurations and constituent materials described in International Publication No. 2005/094130, but the present invention is not limited thereto.

[Each component of the organic EL element]
Next, the details of each component of the organic EL element will be described.

〔Base material〕
The base material 2 applicable to the organic EL element 1 is not particularly limited, and examples thereof include types such as glass and resin base materials, and preferably, flexibility can be imparted to the organic EL element. From the viewpoint, it is a flexible resin base material.

Examples of the resin material constituting the flexible resin base material applicable to the present invention include polyesters such as polyethylene terephthalate (abbreviation: PET) and polyethylene naphthalate (abbreviation: PEN), polyethylene, polypropylene, cellophane, and the like. Cellulose esters such as cellulose diacetate, cellulose triacetate (abbreviation: TAC), cellulose acetate butyrate, cellulose acetate propionate (abbreviation: CAP), cellulose acetate phthalate, cellulose nitrate and their derivatives, polyvinylidene chloride, polyvinyl chloride. Alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate (abbreviation: PC), norbornene resin, polymethylpentene, polyether ketone, polyimide, polyethersulfone (abbreviation: PES), polyphenylene sulfide, polysulfones, polyetherimide, Polyether ketoneimide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic and polyarylates, cycloolefin resins such as arton (trade name, manufactured by JSR) and Apel (trade name, manufactured by Mitsui Chemicals). Can be mentioned.

Among these resin substrates, films such as polyethylene terephthalate (abbreviation: PET), polybutylene terephthalate, polyethylene naphthalate (abbreviation: PEN), and polycarbonate (abbreviation: PC) are flexible in terms of cost and availability. It is preferably used as a resin base material having.

In the present invention, the thickness of the resin base material can be in the range of 3 to 200 μm, preferably in the range of 10 to 100 μm, and more preferably in the range of 20 to 50 μm.

The base material according to the present invention can also be suitably used as a sealing member (transparent base material) for an organic EL element. Further, the resin base material may be an unstretched film or a stretched film.

The resin base material applicable to the present invention can be produced by a conventionally known general film forming method. For example, by melting the resin as a material with an extruder, extruding it with an annular die or a T die, and quenching it, an unstretched resin base material that is substantially amorphous and not oriented can be produced. Further, the unstretched resin base material is subjected to a known method such as uniaxial stretching, tenter-type sequential biaxial stretching, tenter-type simultaneous biaxial stretching, and tubular simultaneous biaxial stretching to convey the resin base material (vertical direction). , MD direction), or in the direction perpendicular to the transport direction of the resin base material (horizontal axis direction, TD direction), the stretched resin base material can be produced. In this case, the draw ratio can be appropriately selected according to the resin used as the raw material of the resin base material, but is preferably in the range of 2 to 10 times in the vertical axis direction and the horizontal axis direction, respectively.

Examples of the glass substrate which is a light-transmitting substrate applicable to the present invention include soda lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, and barium borosilicate glass. , Glass and the like.

[First electrode: anode]
The first electrode (hereinafter, also referred to as an anode) constituting the organic EL element is preferably formed of an oxide semiconductor or a thin metal or alloy, and is, for example, a metal or metal such as Ag or Au. Examples thereof include an alloy containing the above as a main component, CuI, or an oxide semiconductor such as _{a composite oxide of indium tin (ITO), SnO 2 and ZnO.}

When the anode is composed of silver as a main component, the purity of silver is preferably 99% or more. Further, palladium (Pd), copper (Cu), gold (Au) and the like may be added to ensure the stability of silver.

When the anode is composed of silver as a main component, it may be formed of silver alone or may be composed of an alloy containing silver (Ag). Examples of such alloys include silver-magnesium (Ag-Mg), silver-copper (Ag-Cu), silver-palladium (Ag-Pd), silver-palladium-copper (Ag-Pd-Cu), and silver. -Indium (Ag-In) and the like can be mentioned.

Among the constituent materials constituting the anode, the anode constituting the organic EL device according to the present invention is composed mainly of indium tin oxide composite oxide (ITO) or silver and has a thickness of 2 to 20 nm. It is preferable that the anode has a light transmittance within the range of, and more preferably the thickness is within the range of 4 to 12 nm. When the thickness is 20 nm or less, the absorption component and the reflection component of the anode having light transmittance are suppressed to a low level, and a high light transmittance is maintained, which is preferable.

The layer composed mainly of indium-tin oxide composite oxide (ITO) or silver in the present invention means that the content of ITO or silver in the anode is 60% by mass or more, preferably. It is 80% by mass or more, more preferably 90% by mass or more, and particularly preferably the content of ITO or silver is 98% by mass or more. Further, the "light transmittance" of the light-transmitting anode according to the present invention means that the light transmittance at a wavelength of 550 nm is 50% or more.

The light-transmitting anode may have a structure in which layers composed of ITO or silver as a main component are divided into a plurality of layers and laminated, if necessary.

Further, in the present invention, when the anode is a light-transmitting anode composed of silver as a main component, the lower part thereof is formed from the viewpoint of enhancing the uniformity of the silver film of the light-transmitting anode. A base layer can be provided on the surface. The base layer is not particularly limited, but is preferably a layer containing an organic compound having a nitrogen atom or a sulfur atom, and a method of forming a light-transmitting anode on the base layer is preferable. is there.

Further, the extraction electrode 10 of the first electrode according to the present invention is formed of the same material in the form of extending the first electrode. In the present invention, the distinction between the first electrode 3 and the extraction electrode 10 is that the electrode constituting the light emitting region is defined as the first electrode 3, and the other electrodes connected to the conductive member are defined as the extraction electrode 10.

[Organic functional layer unit U]
The production of the organic EL device of the present invention is characterized in that at least one layer (organic layer A) of the organic layer constituting the organic layer unit is formed by using the ink composition of the present invention.

The organic layer A according to the present invention is not particularly limited, but is preferably an electron transporting layer or an electron injecting layer containing an electron transporting material or an electron injecting material as an organic functional material, and particularly preferably electron transporting. It is preferable to apply an ink composition containing an organic functional material specified in the present invention, a fluorinated solvent, and a non-fluorinated solvent having a boiling point of 99 ° C. or higher to form an electron transport layer containing the material. ..

Hereinafter, each layer constituting the organic functional layer unit will be described in sequence, but first, an electron transport layer and an electron injection layer will be described.

(Electronic transport layer)
In the present invention, the electron transport layer may be made of a material having a function of transporting electrons and may have a function of transmitting electrons injected from the cathode to the light emitting layer.

In the organic EL device of the present invention, the total film thickness of the electron transport layer is not particularly limited, but is usually in the range of 2 nm to 5 μm, more preferably 2 to 500 nm, and further preferably 5 to 200 nm. ..

Further, in the organic EL element, when the light generated in the light emitting layer is taken out from the electrode, the light taken out directly from the light emitting layer and the light taken out after being reflected by the electrode located at the opposite electrode to the electrode that takes out the light interfere with each other. Is known to cause. When light is reflected by the cathode, this interference effect can be efficiently utilized by appropriately adjusting the total film thickness of the electron transport layer between several nm and several μm.

On the other hand, if the film thickness of the electron transport layer is increased, the voltage tends to increase. Therefore, especially when the film thickness is thick, the electron mobility of the electron transport layer ^{is preferably 10 to 5} cm ² / Vs or more. ..

The material used for the electron transport layer (hereinafter referred to as "electron transport material") may have any of electron injection property, transport property, and hole barrier property, and is among conventionally known compounds. Any one can be selected and used from.

Examples of the electron transporting material applicable to the electron transporting layer according to the present invention include nitrogen-containing aromatic heterocyclic derivatives (carbazole derivatives, azacarbazole derivatives (one or more carbon atoms constituting the carbazole ring are replaced with nitrogen atoms). , Ppyridine derivative, pyrimidine derivative, pyrazine derivative, pyridazine derivative, triazine derivative, quinoline derivative, quinoxaline derivative, phenanthroline derivative, azatriphenylene derivative, oxazole derivative, thiazole derivative, oxadiazole derivative, thiadiazol derivative, triazole derivative, Benzimidazole derivative, benzoxazole derivative, benzthiazole derivative, etc.), dibenzofuran derivative, azadibenzofuran derivative (one or more carbon atoms constituting the dibenzofuran ring replaced with nitrogen atom), dibenzothiophene derivative, azadibenzothiophene derivative (One or more carbon atoms constituting the dibenzothiophene ring are substituted with nitrogen atoms), silol derivatives, aromatic hydrocarbon ring derivatives (naphthalene derivatives, anthracene derivatives, triphenylene, etc.) and the like.

Further, a metal complex having a quinolinol skeleton or a dibenzoquinolinol skeleton as a ligand, for example, tris (8-quinolinol) aluminum (abbreviation: Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5, 7-Dibromo-8-quinolinol) aluminum, tris (2-methyl-8-quinolinol) aluminum, tris (5-methyl-8-quinolinol) aluminum, bis (8-quinolinol) zinc (abbreviation: Znq), etc., and these. A metal complex in which the central metal of the metal complex of No. 1 is replaced with In, Mg, Cu, Ca, Sn, Ga or Pb can also be used as an electron transport material.

In addition, metal-free or metal phthalocyanine, or those whose terminals are substituted with an alkyl group, a sulfonic acid group, or the like can also be preferably used as an electron transport material. Further, a distyrylpyrazine derivative, which is an organic functional material applied to a light emitting layer described later, can also be used as an electron transport material, and is n-type-Si or n-type like the hole injection layer and the hole transport layer. -Inorganic semiconductors such as SiC can also be used as electron transport materials.

Further, a polymer material in which these materials are introduced into a polymer chain or these materials are used as a polymer main chain can also be used.

In the electron transport layer according to the present invention, the electron transport layer may be doped with a doping material as a guest material to form an electron transport layer having a high n property (electron rich). Examples of the doping material include n-type dopants such as metal compounds and metal compounds such as metal halides. Specific examples of the electron transport layer having such a structure include, for example, JP-A-4-297076, JP-A-10-270172, JP-A-2000-196140, JP-A-2001-102175, J. Mol. Apple. Phys. , 95, 5773 (2004) and the like.

Specific examples of known and preferable electron transporting materials used in the organic EL device of the present invention include, but are not limited to, the compounds described in the following documents.

US Patent No. 6528187, US Patent No. 7230107, US Patent Application Publication No. 2005/0025993, US Patent Application Publication No. 2004/0036077, US Patent Application Publication No. 2009/0115316. , US Patent Application Publication No. 2009/0101870, US Patent Application Publication No. 2009/0179554, International Publication No. 2003/060956, International Publication No. 2008/132805, Appl. Phys. Lett. 75, 4 (1999), Apple. Phys. Lett. 79,449 (2001), Apple. Phys. Lett. 81, 162 (2002), Apple. Phys. Lett. 81, 162 (2002), Apple. Phys. Lett. 79,156 (2001), US Patent No. 7964293, US Patent Application Publication No. 2009/030202, International Publication No. 2004/080975, International Publication No. 2004/063159, International Publication No. 2005/085387 , International Publication No. 2006/067931, International Publication No. 2007/0865552, International Publication No. 2008/114690, International Publication No. 2009/0694242, International Publication No. 2009/066797, International Publication No. 2009/054253, International Publication No. 2011/086935, International Publication No. 2010/150593, International Publication No. 2010/047707, European Patent No. 2311826, Japanese Patent Application Laid-Open No. 2010-251675, Japanese Patent Application Laid-Open No. 2009-209133, Japanese Patent Application Laid-Open No. 2009-209133. -124114, 2008-277810, 2006-156445, 2005-340122, 2003-45662, 2003-31367, 2003-282270. Examples of the compounds described in Japanese Patent Application Laid-Open No. 2012/115034 and the like can be mentioned.

More preferable electron transporting materials in the present invention include pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, triazine derivatives, dibenzofuran derivatives, azadibenzofuran derivatives, dibenzothiophene derivatives, azadibenzothiophene derivatives, carbazole derivatives, azacarbazole derivatives, and benzimidazole derivatives. In addition, a compound formed by combining these can be mentioned.

A preferable compound as a compound used for the electron transport layer of the organic EL device of the present invention includes a compound having a structure represented by the following general formula (1).

In the general formula (1), X represents an oxygen atom or a sulfur atom. X _{1 to} X ₁₂ independently _{represent CR 1} or a nitrogen atom. Of X ₅ and X ₇ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₈ and X ₁₀ , one represents a nitrogen atom and the other represents CR ₁ . R ₁ represents a hydrogen atom or a substituent.

L ₁ is just a bond, or is it a benzene ring, a biphenyl ring, a terphenyl ring, a naphthyl ring, an anthracene ring, a triphenylene ring, a fluorene ring, a pyridine ring, a pyrazine ring, a triazine ring, a pyrimidine ring, a dibenzofuran ring, a dibenzothiophene ring. , Carbazole ring, azadibenzofuran ring, azadibenzothiophene ring, azacarbazole ring, thiophene ring, benzothiophene ring, indole ring, imidazole ring, benzimidazole ring, pyrazole ring or triazole ring. When L ₁ is merely a bond or only a benzene ring having no substituent, it is preferable that at least one of _{the plurality of R 1 represents a heteroaryl group.}

L ₁ may form a fused ring. Further, the _{ring containing X 8 to} X ₁₂ may be a part of the condensed ring. The substituent in the general formula (1) is not limited, and is, for example, an alkyl group (for example, a methyl group, an ethyl group, a trifluoromethyl group, an isopropyl group, etc.), an aryl group (for example, a phenyl group, etc.). , Heteroaryl group (for example, pyridyl group, carbazolyl group, etc.), halogen atom (for example, fluorine atom, etc.), cyano group, or alkyl fluoride group, and those used in the exemplary compounds described below are also preferable.

The R ₁ is a pyridine ring, a pyrazine ring, a triazine ring, a pyrimidine ring, an azadibenfuran ring, an azadibenzothiophene ring, an azacarbazole ring, a quinazoline ring, a quinoxaline ring, a quinoline ring, an isoquinoline ring, a benzoquinoline ring, a benzoisoquinoline ring, and an indole. It is preferable to represent a substituent containing a ring, an indazole ring, an imidazole ring, a benzimidazole ring, a benztriazole ring, a pyrazole ring, a triazole ring, an oxazole ring, a thiazole ring or a carbazole ring.

Further, in the general formula (1), X ₈ and X ₁₂ represent a nitrogen atom and X _{9 to} X ₁₁ represent a CR ₁ , or X ₈ and X ₁₁ represent a nitrogen atom, and X ₉ and X It is preferred that ₁₀ and X ₁₂ represent CR ₁ or that X ₈ and X ₁₀ represent a nitrogen atom and X ₉ , X ₁₁ and X ₁₂ represent CR _1.

The compound having the structure represented by the general formula (1) preferably has the structure represented by the following general formula (2).

In the general formula (2), X represents an oxygen atom or a sulfur atom, and a plurality of Xs in the molecule may be the same or different from each other. X _{1 to} X ₁₀ and X _{13 to} X ₁₆ independently _{represent CR 1} or a nitrogen atom, respectively. Of X ₅ and X ₇ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₈ and X ₁₀ , one represents a nitrogen atom and the other represents CR ₁ . R ₁ represents a hydrogen atom or a substituent.

L ₁ is just a bond, or is it a benzene ring, a biphenyl ring, a naphthyl ring, a terphenyl ring, an anthracene ring, a triphenylene ring, a fluorene ring, a pyridine ring, a pyrazine ring, a triazine ring, a pyrimidine ring, a dibenzofuran ring, a dibenzothiophene ring. , Carbazole ring, azadibenzofuran ring, azadibenzothiophene ring, azacarbazole ring, thiophene ring, benzothiophene ring, indole ring, imidazole ring, benzimidazole ring, pyrazole ring or triazole ring. When L ₁ is merely a bond or a benzene ring having no substituent, it is preferable that at least one of _{the plurality of R 1 represents a heteroaryl group.}

L ₁ may form a fused ring. Further, the _{ring containing X 8 to} X ₁₀ and X _{13 to} X ₁₆ may be a part of the fused ring, respectively. As the substituent used in the general formula (2), the same group as in the general formula (1) is preferable. _{The R 1} used in the general formula (2) is preferably the same as that in the general formula (1).

A specific example of L ₁ is shown below, but it is an example and is not limited thereto.

Specific examples of the compound having the structure represented by the general formula (1) or (2) are shown below.

Further, the compound having the structure represented by the general formula (1) is preferably a compound having the structure represented by the following general formula (3).

In the above general formula (3), X represents an oxygen atom or a sulfur atom. X ₁ , X ₂ , X _{4 to} X ₁₂ and X _{17 to} X ₂₁ each independently _{represent a CR 1} or nitrogen atom. Of X ₅ and X ₇ , one represents a nitrogen atom and the other represents CR ₁ . One of X ₈ and X ₁₀ represents a nitrogen atom and the other represents CR ₁ , or one of X ₁₇ and X ₁₉ represents a nitrogen atom and the other represents CR ₁ . R ₁ represents a hydrogen atom or a substituent.

L ₁ and L ₂ are mere bonds, or are benzene ring, biphenyl ring, terphenyl ring, naphthyl ring, anthracene ring, triphenylene ring, fluorene ring, pyridine ring, pyrazine ring, triazine ring, pyrimidine ring, dibenzofuran ring. , Dibenzothiophene ring, carbazole ring, azadibenzofuran ring, azadibenzothiophene ring, azacarbazole ring, thiophene ring, benzothiophene ring, indol ring, imidazole ring, benzimidazole ring, pyrazole ring or triazole ring. Represents. L ₁ and L _2, or also a single bond, in the case of only a benzene ring having no substituent, it is preferable that at least one of the plurality of R ₁ represents a heteroaryl group.

L ₁ and L ₂ may form a fused ring. Further, the _{ring containing X 8 to} X ₁₂ or the ring containing X _{17 to} X ₂₁ may be a part of the condensed ring.

As the substituent used in the general formula (3), the same group as in the general formula (1) is preferable. _{The R 1} used in the general formula (3) is preferably the same as that in the general formula (1). Specific examples of the linking group used in L ₂ include the same as the specific example of L ₁ given in the general formula (1).

Further, in the general formula (3), X ₈ and X ₁₂ represent a nitrogen atom and X _{9 to} X ₁₁ represent CR ₁ , or X ₈ and X ₁₁ represent a nitrogen atom, and X ₉ and X ₁₀ and X ₁₂ represent CR ₁ , or X ₈ and X ₁₀ represent nitrogen atoms, X ₉ , X ₁₁ and X ₁₂ represent CR ₁ , and / or X ₁₇ and X ₂₁ represent nitrogen. X _{18 to} X ₂₀ represent CR ₁ , or X ₁₇ and X ₂₀ represent nitrogen atoms, and X ₁₈ , X ₁₉ and X ₂₁ represent CR ₁ , or X ₁₇ and X It is preferred that ₁₉ represents a nitrogen atom and X ₁₈ , X ₂₀ and X ₂₁ represent CR _1.

Further, the compound having the structure represented by the general formula (3) is preferably a compound having the structure represented by the following general formula (4).

In the above general formula (4), X represents an oxygen atom or a sulfur atom, and a plurality of Xs in the molecule may be the same or different from each other. X ₁ , X ₂ , X _{4 to} X ₁₂ , X ₁₇ , X ₁₈ , and X _{22 to} X ₂₉ each independently _{represent CR 1} or a nitrogen atom. Of X ₅ and X ₇ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₂₂ and X ₂₄ , one represents a nitrogen atom and the other represents CR ₁ . R ₁ represents a hydrogen atom or a substituent.

L ₁ , L ₂ , and L ₃ are merely bonds, or are benzene ring, biphenyl ring, terphenyl ring, naphthyl ring, anthracene ring, triphenylene ring, fluorene ring, pyridine ring, pyrazine ring, triazine ring, pyrimidine ring. , Dibenzofuran ring, dibenzothiophene ring, carbazole ring, azadibenzofuran ring, azadibenzothiophene ring, azacarbazole ring, thiophene ring, benzothiophene ring, indole ring, imidazole ring, benzimidazole ring, pyrazole ring or triazole ring. Represents the linking group of. L _1, is L _2, L _3, or also a single bond, in the case of only a benzene ring having no substituent, it is preferable that at least one of the plurality of R ₁ represents a heteroaryl group.

L ₁ , L ₂ , and L ₃ may form a fused ring. Further, the _{ring containing X 8 to} X ₁₂ or the ring containing X _{25 to} X ₂₉ may be a part of the condensed ring.

As the substituent used in the general formula (4), the same group as in the general formula (1) is preferable. _{The R 1} used in the general formula (4) is preferably the same as that in the general formula (1). Specific examples of the linking group used in L ₂ and L _{3 include the same specific examples of L 1} given in the general formula (1).

Further, in the general formula (4) _{, at least one of X 8 to} X ₁₂ represents a nitrogen atom and the rest represents CR ₁ , and / or at least one of _{X 25 to} X _{29 represents nitrogen.} It is preferred that it represents an atom and the rest represents CR _1.

Further, the compound having the structure represented by the general formula (2) is preferably a compound having the structure represented by the following general formula (5).

In the above general formula (5), X represents an oxygen atom or a sulfur atom, and a plurality of Xs in the molecule may be the same or different from each other. X _{1 to} X ₁₀ and X _{13 to} X ₁₆ independently _{represent CR 1} or a nitrogen atom, respectively. Of X ₅ and X ₇ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₈ and X ₁₀ , one represents a nitrogen atom and the other represents CR ₁ . R ₁ represents a hydrogen atom or a substituent.

m1 and m2 represent 1, 2 or 3, respectively, and 3 ≦ m1 + m2 ≦ 4.

L ₁ is just a bond, or is it a benzene ring, a biphenyl ring, a naphthyl ring, a terphenyl ring, an anthracene ring, a triphenylene ring, a fluorene ring, a pyridine ring, a pyrazine ring, a triazine ring, a pyrimidine ring, a dibenzofuran ring, a dibenzothiophene ring. , Carbazole ring, azadibenzofuran ring, azadibenzothiophene ring, azacarbazole ring, thiophene ring, benzothiophene ring, indole ring, imidazole ring, benzimidazole ring, pyrazole ring or triazole ring. ..

When L ₁ is merely a bond or only a benzene ring having no substituent, it is preferable that at least one of _{the plurality of R 1 represents a heteroaryl group.}

L ₁ may form a fused ring. Further, the _{ring containing X 1 to} X ₇ or the ring containing X _{8 to} X ₁₀ and X _{13 to} X ₁₆ may be a part of the fused ring, respectively.

The substituent used in the general formula (5) is preferably the same as that in the general formula (1). _{The R 1} used in the general formula (5) is preferably the same as that in the general formula (1). Specific examples of the linking group used in L _{1 include the same specific examples of L 1} given in the general formula (1).

Further, the compound having the structure represented by the general formula (4) is preferably a compound having the structure represented by the following general formula (6).

In the above general formula (6), X represents an oxygen atom or a sulfur atom, and a plurality of Xs in the molecule may be the same or different from each other. X ₁ , X ₂ , X _{4 to} X ₁₂ and X ₁₇ , X ₁₈ , X _{21 to} X ₂₉ each independently _{represent a CR 1} or nitrogen atom. Of X ₅ and X ₇ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₂₂ and X ₂₄ , one represents a nitrogen atom and the other represents CR ₁ . R ₁ represents a hydrogen atom or a substituent.

m1 and m2 represent 1, 2 or 3, respectively, and 3 ≦ m1 + m2 ≦ 4.

L ₁ , L ₂ , and L ₃ are merely bonds, or are benzene ring, biphenyl ring, terphenyl ring, naphthyl ring, anthracene ring, triphenylene ring, fluorene ring, pyridine ring, pyrazine ring, triazine ring, pyrimidine ring. , Dibenzofuran ring, dibenzothiophene ring, carbazole ring, azadibenzofuran ring, azadibenzothiophene ring, azacarbazole ring, thiophene ring, benzothiophene ring, indol ring, imidazole ring, benzimidazole ring, pyrazole ring or triazole ring (m1 + m2) ) Represents a valence linking group. L _1, is L _2, L _3, or also a single bond, in the case of only a benzene ring having no substituent, it is preferable that at least one of the plurality of R ₁ represents a heteroaryl group.

L ₁ , L ₂ , and L ₃ may form a fused ring. Further, the _{ring containing X 8 to} X ₁₂ or the ring containing X _{25 to} X ₂₉ may be a part of the condensed ring.

As the substituent used in the general formula (6), the same group as in the general formula (1) is preferable. _{The R 1} used in the general formula (6) is preferably the same as that in the general formula (1). Specific examples of the linking group used in L ₂ and L _{3 include the same specific examples of L 1} given in the general formula (1).

Further, in the general formula (6) _{, at least one of X 8 to} X ₁₂ represents a nitrogen atom and the rest represents CR ₁ , or at least one of _{X 25 to} X _{29 represents a nitrogen atom.} It is preferable that the rest represents CR _1.

Further, the compound having the structure represented by the general formula (2) is preferably a compound having the structure represented by the following general formula (7).

In the general formula (7), X represents an oxygen atom or a sulfur atom, and a plurality of Xs in the molecule may be the same or different from each other. X ₁ , X ₂ , X _{4 to} X ₁₀ , X _{13 to} X ₁₈ , and X _{21 to} X ₂₉ each independently _{represent CR 1} or a nitrogen atom. Of X ₅ and X ₇ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₈ and X ₁₀ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₂₂ and X ₂₄ , one represents a nitrogen atom and the other represents CR ₁ . R ₁ represents a hydrogen atom or a substituent.

m1 and m2 represent 1, 2 or 3, respectively, and 2 ≦ m1 + m2 ≦ 4.

L ₁ , L ₂ , and L ₃ are merely bonds, or are benzene ring, biphenyl ring, terphenyl ring, naphthyl ring, anthracene ring, triphenylene ring, fluorene ring, pyridine ring, pyrazine ring, triazine ring, pyrimidine ring. , Dibenzofuran ring, dibenzothiophene ring, carbazole ring, azadibenzofuran ring, azadibenzothiophene ring, azacarbazole ring, thiophene ring, benzothiophene ring, indol ring, imidazole ring, benzimidazole ring, pyrazole ring or triazole ring (m1 + m2) ) Represents a valence linking group. L _1, is L _2, L _3, or also a single bond, in the case of only a benzene ring having no substituent, it is preferable that at least one of the plurality of R ₁ represents a heteroaryl group.

L ₁ , L ₂ , and L ₃ may form a fused ring. Further, the _{ring containing X 8 to} X ₁₂ or the ring containing X _{25 to} X ₂₉ may be a part of the condensed ring.

As the substituent used in the general formula (7), the same group as in the general formula (1) is preferable. _{The R 1} used in the general formula (7) is preferably the same as that in the general formula (1). Specific examples of the linking group used in L ₂ and L _{3 include the same specific examples of L 1} given in the general formula (1).

Further, in the general formula (7), it is preferable that _{at least one of X 25 to} X ₂₉ represents a nitrogen atom and the rest represents CR _1.

Further, the compound having the structure represented by the general formula (4) is preferably a compound having the structure represented by the following general formula (8).

In the above general formula (8), X represents an oxygen atom or a sulfur atom, and a plurality of Xs in the molecule may be the same or different from each other. X ₁ , X ₂ , X _{4 to} X ₁₀ , X _{13 to} X ₁₈ , and X _{21 to} X ₂₉ each independently _{represent CR 1} or a nitrogen atom. Of X ₅ and X ₇ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₈ and X ₁₀ , one represents a nitrogen atom and the other represents CR ₁ . Of X ₂₂ and X ₂₄ , one represents a nitrogen atom and the other represents CR ₁ . R ₁ represents a hydrogen atom or a substituent.

m1 and m2 represent 1, 2 or 3, respectively, and 2 ≦ m1 + m2 ≦ 4.

L ₁ , L ₂ , and L ₃ are merely bonds, or are benzene ring, biphenyl ring, terphenyl ring, naphthyl ring, anthracene ring, triphenylene ring, fluorene ring, pyridine ring, pyrazine ring, triazine ring, pyrimidine ring. , Dibenzofuran ring, dibenzothiophene ring, carbazole ring, azadibenzofuran ring, azadibenzothiophene ring, azacarbazole ring, thiophene ring, benzothiophene ring, indol ring, imidazole ring, benzimidazole ring, pyrazole ring or triazole ring (m1 + m2) ) Represents a valence linking group. L _1, is L _2, L _3, or also a single bond, in the case of only a benzene ring having no substituent, it is preferable that at least one of the plurality of R ₁ represents a heteroaryl group. L ₁ , L ₂ , and L ₃ may form a fused ring. Further, the _{ring containing X 25 to} X ₂₉ may be a part of the condensed ring.

As the substituent used in the general formula (8), the same group as in the general formula (1) is preferable. _{The R 1} used in the general formula (8) is preferably the same as that in the general formula (1). Specific examples of the linking group used in L ₂ and L _{3 include the same specific examples of L 1} given in the general formula (1).

Further, in the general formula (8), it is preferable that _{at least one of X 25 to} X ₂₉ represents a nitrogen atom and the rest represents CR _1.

Examples of the compounds having the structures represented by the general formulas (3) to (8) include the following compounds M-360 to M-436.

Examples of other compounds applicable to the electron transport layer of the organic EL device of the present invention include compounds 1 to 213 described in Japanese Patent No. 5604848 and compounds 1 to 264 described in Japanese Patent No. 5589251. , Etc. are also preferable.

The electron transport layer according to the present invention comprises an ink composition containing at least an organic functional material, a fluorine-based solvent, and a non-fluorine-based solvent having a boiling point of 99 ° C. or higher, for example, a spin coating method, a casting method, or a gravure coating method. It can be formed by thinning it by a known method such as an inkjet printing method, but the present invention is particularly characterized in that it is formed by using an inkjet printing method.

(Electron injection layer)
In the present invention, a method of forming an electron injection layer by an inkjet printing method using the ink composition of the present invention is also one of the preferred embodiments.

The electron injection layer is a layer provided between the cathode and the light emitting layer in order to reduce the driving voltage and improve the emission brightness, and when the cathode is composed of the light-transmitting electrode according to the present invention. Is provided adjacent to the light-transmitting electrode, and is provided in "Organic EL Element and Its Industrial Frontline (Published by NTS Co., Ltd. on November 30, 1998)", Volume 2, Chapter 2, " It is described in detail in "Electrode Material" (pages 123-166).

The details of the electron-injected layer are also described in JP-A-6-325871, JP-A-9-17574, JP-A-10-74586, and the like, and specific examples of materials preferably used for the electron-injected layer include , Metals such as strontium and aluminum, alkali metal compounds such as lithium fluoride, sodium fluoride and potassium fluoride, and alkali metal halide layers such as magnesium fluoride and calcium fluoride. Examples thereof include an alkaline earth metal compound layer, a metal oxide typified by molybdenum oxide and aluminum oxide, and a metal complex typified by lithium 8-hydroxyquinolate (Liq). When the light-transmitting electrode in the present invention is a cathode, an organic material such as a metal complex is particularly preferably used. The electron injection layer is preferably a very thin film, and the layer thickness is preferably in the range of 1 nm to 10 μm, although it depends on the constituent materials.

(Light emitting layer)
A phosphorescent compound or a fluorescent compound can be used as the light emitting material in the light emitting layer constituting the organic EL element of the present invention, but in the present invention, the phosphorescent compound is particularly used as the light emitting material. The composition contained is preferable.

The light emitting layer constituting the organic EL element is a layer in which electrons injected from the electrode or the electron transport layer and holes injected from the hole transport layer recombine to emit light, and the light emitting portion is a light emitting layer. It may be in the layer of the light emitting layer or at the interface between the light emitting layer and the adjacent layer.

The configuration of such a light emitting layer is not particularly limited as long as the contained light emitting material satisfies the light emitting requirements.

The total thickness of the light emitting layer is preferably in the range of 1 to 100 nm, and more preferably in the range of 1 to 30 nm because a lower driving voltage can be obtained. The total thickness of the light emitting layers is the thickness including the non-light emitting intermediate layer when there is a non-light emitting intermediate layer between the light emitting layers.

In the light emitting layer, a plurality of light emitting materials may be mixed, or a phosphorescent light emitting material and a fluorescent light emitting material may be mixed and used in the same light emitting layer. It is preferable that the light emitting layer contains a host compound (also referred to as a light emitting host or the like) and a light emitting material (also referred to as a light emitting dopant) and emits light from the light emitting material.

The light emitting layer as described above can be obtained by using a light emitting material or a host compound described later, for example, a vacuum deposition method, a spin coating method, a casting method, a clavier coating method, an LB method (Langmuir Brodget method) and an inkjet printing method. However, in the present invention, it is preferably formed by a wet coating method such as a pin coating method, a casting method, a clavier coating method, or an inkjet printing method, and in particular, it is formed by an inkjet printing method. It is preferable to do so.

<Host compound>
As the host compound contained in the light emitting layer, a compound having a phosphorescent quantum yield of phosphorescent emission at room temperature (25 ° C.) of less than 0.1 is preferable. Further, the phosphorus photon yield is preferably less than 0.01. Further, among the compounds contained in the light emitting layer, the volume ratio in the layer is preferably 50% or more.

As the host compound, a known host compound may be used alone, or a plurality of types of host compounds may be used. By using a plurality of types of host compounds, it is possible to adjust the movement of electric charges, and it is possible to improve the efficiency of the organic electroluminescent device. Further, by using a plurality of types of light emitting materials described later, it is possible to mix different light emitting materials, whereby an arbitrary light emitting color can be obtained.

The host compound used in the light emitting layer may be a conventionally known low molecular weight compound or a high molecular weight compound having a repeating unit, and a low molecular weight compound having a polymerizable group such as a vinyl group or an epoxy group (deposited polymerizable light emitting host). ) May be used.

Examples of the host compound applicable to the present invention include Japanese Patent Application Laid-Open No. 2001-257076, Japanese Patent Application Laid-Open No. 2001-357977, Japanese Patent Application Laid-Open No. 2002-8860, Japanese Patent Application Laid-Open No. 2002-43056, and Japanese Patent Application Laid-Open No. 2002-105445. 2002-352957, 2002-231453, 2002-234888, 2002-260861, 2002-305083, US Patent Application Publication No. 2005/0112407, US Patent Application Publication 2009/0030202, International Publication No. 2001/039234, International Publication No. 2008/056746, International Publication No. 2005/089025, International Publication No. 2007/0637554, International Publication No. 2005/030900, International Publication No. Examples thereof include compounds described in No. 2009/086028, International Publication No. 2012/023947, Japanese Patent Application Laid-Open No. 2007-254297, European Patent No. 2034538 and the like.

<Luminescent material>
Examples of the light emitting material that can be used in the present invention include a phosphorescent compound (also referred to as a phosphorescent compound, a phosphorescent material or a phosphorescent dopant) and a phosphorescent compound (also referred to as a phosphorescent compound or a phosphorescent material). However, it is particularly preferable to use a phosphorescent compound from the viewpoint of obtaining high luminescence efficiency.

<1> Phosphorescent compound A phosphorescent compound is a compound in which light emission from an excited triple term is observed, specifically, a compound that emits phosphorescent light at room temperature (25 ° C.), and is a phosphorescent quantum. A compound having a yield of 0.01 or more at 25 ° C. is defined as a compound having a preferable phosphorescence quantum yield of 0.1 or more.

The phosphorus photon yield can be measured by the method described on page 398 (1992 edition, Maruzen) of Spectroscopy II of the 4th edition Experimental Chemistry Course 7. The phosphorescence quantum yield in a solution can be measured using various solvents, but when the phosphorescence luminescent compound is used in the present invention, the phosphorescence quantum yield in any of the solvents is 0.01 or more. Should be achieved.

The phosphorescent compound can be appropriately selected from known compounds used for the light emitting layer of a general organic EL element, and preferably contains a metal of Group 8 to 10 in the periodic table of the element. It is a complex-based compound, more preferably an iridium compound, an osmium compound, a platinum compound (platinum complex-based compound) or a rare earth complex, and the most preferable is an iridium compound.

In the present invention, at least one light emitting layer may contain two or more kinds of phosphorescent compounds, and the concentration ratio of the phosphorescent compounds in the light emitting layer changes in the thickness direction of the light emitting layer. It may be in the above mode.

Specific examples of known phosphorescent compounds that can be used in the present invention include compounds described in the following documents.

Nature 395, 151 (1998), Apple. Phys. Lett. 78, 1622 (2001), Adv. Mater. 19,739 (2007), Chem. Mater. 17, 3532 (2005), Adv. Mater. 17,1059 (2005), International Publication No. 2009/10991, International Publication No. 2008/101842, International Publication No. 2003/040257, US Patent Application Publication No. 2006/835469, US Patent Application Publication No. 2006 / Examples thereof include the compounds described in US Pat. No. 0202194, US Patent Application Publication No. 2007/0087321, US Patent Application Publication No. 2005/0244673, and the like.

In addition, Inorg. Chem. 40,1704 (2001), Chem. Mater. 16,2480 (2004), Adv. Mater. 16, 2003 (2004), Angew. Chem. Int. Ed. 2006, 45, 7800, Apple. Phys. Lett. 86,153505 (2005), Chem. Lett. 34,592 (2005), Chem. Commun. 2906 (2005), Inorg. Chem. 42,1248 (2003), International Publication No. 2009/050290, International Publication No. 2009/000673, US Patent No. 7332232, US Patent Application Publication No. 2009/00397776, US Patent No. 6688266. , US Patent Application Publication No. 2006/0008670, US Patent Application Publication No. 2008/0015355, US Patent Application Publication No. 7396598, US Patent Application Publication No. 2003/01386657, US Patent No. 70090928. Examples of the compounds described in the specification and the like can be mentioned.

In addition, Angew. Chem. Int. Ed. 47, 1 (2008), Chem. Mater. 18,5119 (2006), Inorg. Chem. 46,4308 (2007), Organometallics 23,3745 (2004), Apple. Phys. Lett. 74,1361 (1999), International Publication No. 2006/056418, International Publication No. 2005/123873, International Publication No. 2006/082742, US Patent Application Publication No. 2005/0260441, US Patent No. 7534505 , US Patent Application Publication No. 2007/0190359, US Patent No. 7338722, US Patent No. 7279704, US Patent Application Publication No. 2006/103874, and the like. ..

Furthermore, International Publication No. 2005/076380, International Publication No. 2008/140115, International Publication No. 2011/134013, International Publication No. 2010/086089, International Publication No. 2012/20327, International Publication No. 2011/051404 , International Publication No. 2011/073149, JP-A-2009-114086, JP-A-2003-81988, JP-A-2002-363552, and the like.

In the present invention, preferred phosphorescent compounds include organometallic complexes having Ir as the central metal. More preferably, a complex containing at least one coordination mode of metal-carbon bond, metal-nitrogen bond, metal-oxygen bond and metal-sulfur bond is preferable.

The phosphorescent compounds described above are described, for example, in Organic Letters, vol3, No. 16, 2579-2581 (2001), Inorganic Chemistry, Vol. 30, No. 8, pp. 1685-1687 (1991), J. Mol. Am. Chem. Soc. , 123, 4304 (2001), Inorganic Chemistry, 40, 7, 1704-1711 (2001), Inorganic Chemistry, 41, 12, 3055-3066 (2002). , New Journal of Chemistry. , Vol. 26, p. 1171 (2002), European Journal of Organic Chemistry, Vol. 4, p. 695-709 (2004), and the methods disclosed in the references described in these documents. Can be synthesized by applying.

<2> Fluorescent luminescent compounds Examples of the fluorescent luminescent compound include coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, and pyrylium dyes. Examples thereof include dyes, perylene dyes, fluorescein dyes, polythiophene dyes, rare earth complex phosphors and the like.

(Charge injection layer)
The charge injection layer is a layer provided between the electrode and the light emitting layer in order to reduce the driving voltage and improve the light emitting brightness. The details are described in Chapter 2 "Electrode Materials" (pages 123 to 166) of Volume 2 of "S Co., Ltd.", and there are a hole injection layer and the above-mentioned electron injection layer.

The charge injection layer is generally between the anode and the light emitting layer or the hole transport layer in the case of the hole injection layer, and between the cathode and the light emitting layer or the electron transport layer in the case of the electron injection layer described above. Although it can be present, a configuration in which the charge injection layer is arranged adjacent to the electrode having light transmission is preferable.

The hole injection layer is a layer that is arranged adjacent to the anode, which is one of the electrodes, in order to reduce the driving voltage and improve the emission brightness. It is described in detail in Chapter 2 "Electrode Materials" (pages 123-166) of Volume 2 of "NTS".

The details of the hole injection layer are also described in JP-A-9-45479, 9-2660062, 8-288609, etc., and examples of the material used for the hole injection layer include , Porphyrin derivative, phthalocyanine derivative, oxazole derivative, oxadiazole derivative, triazole derivative, imidazole derivative, pyrazoline derivative, pyrazolone derivative, phenylenediamine derivative, hydrazone derivative, stillben derivative, polyarylalkane derivative, triarylamine derivative, carbazole derivative Indrocarbazole derivatives, isoindole derivatives, acene derivatives such as anthracene and naphthalene, fluorene derivatives, fluorenone derivatives, and polymer materials or oligomers with polyvinylcarbazole and aromatic amines introduced into the main and side chains, polysilanes, and conductivity. Examples thereof include polymers or oligomers (for example, PEDOT (polyethylene dioxythiophene): PSS (polystyrene sulfonic acid), aniline-based copolymers, polyaniline, polythiophene, etc.).

Examples of the triarylamine derivative include a benzidine type represented by 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (abbreviation: α-NPD) and 4,4', 4 ". -Tris [N- (3-methylphenyl) -N-phenylamino] triphenylamine) (abbreviation: MTDATA) typified by starburst type, triarylamine compound having fluorene or anthracene in the linking core, etc. Be done.

Hexaazatriphenylene derivatives as described in JP-A-2003-591432 and JP-A-2006-135145 can also be used as the hole transport material in the same manner.

(Hole transport layer)
The hole transport layer is made of a hole transport material having a function of transporting holes, and in a broad sense, a hole injection layer and an electron blocking layer also have a function of a hole transport layer. The hole transport layer may be provided as a single layer or a plurality of layers.

The hole transporting material has either injection or transport of holes or an electron barrier property, and may be either an organic substance or an inorganic substance. For example, triazole derivatives, oxaziazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazole derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, Examples thereof include stillben derivatives, silazane derivatives, aniline-based copolymers, conductive polymer oligomers and thiophene oligomers.

As the hole transporting material, the above-mentioned compounds can be used, but porphyrin compounds, aromatic tertiary amine compounds and styrylamine compounds can be used, and in particular, aromatic tertiary amine compounds are used. Is preferable.

Typical examples of aromatic tertiary amine compounds and styrylamine compounds are N, N, N', N'-tetraphenyl-4,4'-diaminophenyl, N, N'-diphenyl-N, N'-. Bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine (abbreviation: TPD), 2,2-bis (4-di-p-tolylaminophenyl) propane, 1,1 -Bis (4-di-p-tolylaminophenyl) cyclohexane, N, N, N', N'-tetra-p-tolyl-4,4'-diaminobiphenyl, 1,1-bis (4-di-p) -Trillaminophenyl) -4-phenylcyclohexane, bis (4-dimethylamino-2-methylphenyl) phenylmethane, bis (4-di-p-tolylaminophenyl) phenylmethane, N, N'-diphenyl-N, N'-di (4-methoxyphenyl) -4,4'-diaminobiphenyl, N, N, N', N'-tetraphenyl-4,4'-diaminodiphenyl ether, 4,4'-bis (diphenylamino) Quadriphenyl, N, N, N-tri (p-tolyl) amine, 4- (di-p-tolylamino) -4'-[4- (di-p-tolylamino) styryl] stilben, 4-N, N Examples thereof include −diphenylamino- (2-diphenylvinyl) benzene, 3-methoxy-4'-N, N-diphenylaminostillbenzene and N-phenylcarbazole.

The hole transport layer uses the above hole transport material, for example, a vacuum deposition method, a spin coating method, a casting method, a clavier coating method, a printing method including an inkjet printing method, and an LB method (Langmuir Brodgett method). Although it can be formed by thinning by a known method such as, in the present invention, it is preferable to apply a wet coating method such as a pin coating method, a casting method, a Clavier coating method, or an inkjet printing method. The thickness of the hole transport layer is not particularly limited, but is usually in the range of about 5 nm to 5 μm, preferably in the range of 5 to 200 nm. The hole transport layer may have a one-layer structure composed of one or more of the above materials.

Further, the p property can be enhanced by doping the material of the hole transport layer with impurities. Examples thereof include JP-A-4-297076, JP-A-2000-196140, JP-A-2001-102175, and J. Am. Apple. Phys. , 95, 5773 (2004) and the like.

As described above, it is preferable to increase the p property of the hole transport layer because a device having lower power consumption can be manufactured.

(Blocking layer)
Examples of the blocking layer include a hole blocking layer and an electron blocking layer, which are layers provided as needed in addition to the constituent layers of the carrier transport function layer unit 3 described above. For example, it is described in JP-A-11-204258, No. 11-204359, and page 237 of "Organic EL Element and Its Industrialization Frontline (November 30, 1998, published by NTS Co., Ltd.)". Examples include a hole blocking (hole block) layer.

The hole blocking layer has a function of an electron transporting layer in a broad sense. The hole blocking layer is made of a hole blocking material that has a function of transporting electrons and a significantly small ability to transport holes, and recombines electrons and holes by blocking holes while transporting electrons. The probability can be improved. In addition, the structure of the electron transport layer can be used as a hole blocking layer, if necessary. The hole blocking layer is preferably provided adjacent to the light emitting layer.

On the other hand, the electron blocking layer has a function of a hole transporting layer in a broad sense. The electron blocking layer is made of a material that has a function of transporting holes and has a significantly small ability to transport electrons. By blocking electrons while transporting holes, the probability of recombination of electrons and holes is improved. Can be made to. In addition, the structure of the hole transport layer can be used as an electron blocking layer, if necessary. The layer thickness of the hole blocking layer applied to the present invention is preferably in the range of 3 to 100 nm, and more preferably in the range of 5 to 30 nm.

[Second electrode: cathode]
The cathode is an electrode film that functions to supply electrons to the organic functional layer group and the light emitting layer, and a metal, an alloy, an organic or inorganic conductive compound, or a mixture thereof is used. Specifically, when a dry forming method such as a vapor deposition method is used, gold, aluminum, silver, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, ittium / silver mixture, magnesium / aluminum mixture, magnesium / Examples thereof include indium mixtures, indium, lithium / aluminum mixtures, rare earth metals, oxide semiconductors such as _{ITO, ZnO, TiO 2} and SnO _2.

When formed by a wet coating method, a pin coating method or casting is performed using a composite (PEDOT: PSS) of poly (3,4-ethylenedioxythiophene) and polystyrene sulfonic acid, silver nanoink, or the like. It can be formed by a method, a clavier coating method, an inkjet printing method, or the like.

The cathode can be produced by forming a thin film of these conductive materials by a method such as vapor deposition or sputtering. The sheet resistance as the second electrode is several hundred Ω / sq. The following is preferable, and the film thickness is usually selected in the range of 5 nm to 5 μm, preferably 5 to 200 nm.

In the case of the double-sided light emitting type in which the organic EL element also extracts the emitted light L from the cathode side, a cathode having good light transmission may be selected and configured.

[Sealing member]
Examples of the sealing means used for sealing the organic EL element include a method of bonding the flexible sealing member, the cathode and the transparent base material with a sealing adhesive.

The sealing member may be arranged so as to cover the display area of the organic EL element, and may be intaglio-shaped or flat-plate-shaped. Further, transparency and electrical insulation are not particularly limited.

Specific examples thereof include a thin film glass plate, a polymer plate, a film, and a metal film (metal foil) having flexibility. Examples of the glass plate include soda lime glass, barium / strontium-containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, and quartz. Examples of the polymer plate include polycarbonate, acrylic, polyethylene terephthalate, polyether sulfide, polysulfone and the like. Examples of the metal film include one or more metals or alloys selected from the group consisting of stainless steel, iron, copper, aluminum, magnesium, nickel, zinc, chromium, titanium, molybdenum, silicon, germanium and tantalum.

In the present invention, a polymer film and a metal film can be preferably used as the sealing member from the viewpoint that the organic EL element can be thinned. ^{Further, the polymer film has a water vapor permeability of 1 × 10 -3} g / m ² at a temperature of 25 ± 0.5 ° C. and a relative humidity of 90 ± 2% RH measured by a method according to JIS K 7129-1992. preferably 24h or less, and further, the oxygen permeability measured in compliance with the method provided in JIS K 7126-1987 ^{is, 1 × 10 -3 mL / m} 2 · 24h · atm (1atm is 1.01325 × 10 ⁵ a Pa) equal to or lower than a temperature of 25 ± 0.5 ° C., water vapor permeability at a relative humidity of 90 ± 2% RH is preferably not more than ^{1 × 10 -3 g / m 2} · 24h.

Examples of the sealing adhesive include acrylic acid-based oligomers, photocurable and thermosetting adhesives having a reactive vinyl group of methacrylic acid-based oligomers, and moisture-curable adhesives such as 2-cyanoacrylic acid ester. Can be mentioned. In addition, heat and chemical curing type (two-component mixture) such as epoxy type can be mentioned. Further, hot melt type polyamide, polyester and polyolefin can be mentioned. In addition, a cation-curable type ultraviolet-curable epoxy resin adhesive can be mentioned.

<< Manufacturing method of organic EL element >>
The method for producing an organic EL element of the present invention is characterized in that the organic layer A according to the present invention is formed by using an inkjet head by an inkjet printing method using the ink composition of the present invention.

(Inkjet printing method)
Hereinafter, an example of the method for forming the organic layer by the inkjet printing method will be described with reference to the drawings.

FIG. 2 is a schematic view showing an example of a method for manufacturing an organic EL element using an inkjet printing method.

In FIG. 2, an inkjet printing apparatus equipped with an inkjet head 30 is used to form an organic functional material for forming an organic layer of an organic EL element on a base material (2), a fluorinated solvent, and a boiling point of 99 ° C. An example of the above-mentioned method for ejecting an ink composition containing a non-fluorine-based solvent is shown.

As shown in FIG. 2, as an example, while continuously transporting the base material 2, the ink composition having the configuration specified in the present invention is sequentially transferred onto the base material 2 as ink droplets by the inkjet head 30. Inject to form the organic functional layer group U of the organic EL element.

The inkjet head 30 applicable to the method for manufacturing an organic EL element of the present invention is not particularly limited. For example, the ink pressure chamber has a diaphragm provided with a piezoelectric element, and the pressure in the ink pressure chamber by the diaphragm. It may be a shear mode type (piezo type) head that ejects the ink composition by change, or it has a heat generating element, and the ink from the nozzle due to a sudden volume change due to the film boiling of the ink composition due to the heat energy from this heat generating element. It may be a thermal type head that discharges the composition.

An ink composition supply mechanism for injection is connected to the inkjet head 30. The ink composition is supplied to the inkjet head 30 by the tank 38A. In this example, the liquid level in the tank is kept constant so that the pressure of the ink composition in the inkjet head 30 is always kept constant. As a method, the ink composition is overflowed from the tank 38A and returned to the tank 38B by natural flow. The ink composition is supplied from the tank 38B to the tank 38A by the pump 31, and the liquid level of the tank 38A is controlled to be stable and constant according to the injection conditions.

When returning the ink composition to the tank 38A by the pump 31, the ink composition is returned to the tank 38A after passing through the filter 32. As described above, it is preferable that the ink composition is passed through a filter medium having an absolute filtration accuracy or a quasi-absolute filtration accuracy of 0.05 to 50 μm at least once before being supplied to the inkjet head 30.

Further, the ink composition can be forcibly supplied from the tank 36 and the cleaning solvent can be forcibly supplied from the tank 37 to the inkjet head 30 by the pump 39 in order to perform the cleaning work and the liquid filling work of the inkjet head 30. Such tank pumps may be divided into a plurality of such tank pumps with respect to the inkjet head 30, a branch of a pipe may be used, or a combination thereof may be used.

In FIG. 2, the pipe branch 33 is used. Further, in order to sufficiently remove the air in the inkjet head 30, the ink composition is forcibly sent from the tank 36 to the inkjet 30 by using a pump 39, and the ink composition is extracted from the air bleeding pipe described below to be a waste liquid. It may be sent to the tank 34.

3A and 3B are schematic external views showing an example of an inkjet head structure applicable to an inkjet printing method.

FIG. 3A is a schematic perspective view showing an inkjet head 100 applicable to the present invention, and FIG. 3B is a bottom view of the inkjet head 100.

The inkjet head 100 applicable to the present invention is mounted on an inkjet recording device (not shown), and includes a head chip that ejects ink from a nozzle, a wiring board on which the head chip is arranged, and this wiring. A drive circuit board connected via a substrate and a flexible substrate, a manifold for introducing ink into a channel of a head chip via a filter, a housing 56 in which a manifold is housed inside, and a bottom opening of the housing 56. The cap receiving plate 57 attached so as to close the above, the first and second joints 81a and 81b attached to the first ink port and the second ink port of the manifold, and the third ink port attached to the third ink port of the manifold. It includes a 3-joint 82 and a cover member 59 attached to the housing 56. Further, mounting holes 68 for mounting the housing 56 on the printer main body side are formed.

Further, the cap receiving plate 57 shown in FIG. 3B is formed as a substantially rectangular plate whose outer shape is long in the left-right direction corresponding to the shape of the cap receiving plate mounting portion 62, and a plurality of nozzles are formed in the substantially central portion thereof. In order to expose the arranged nozzle plate 61, a long nozzle opening 71 is provided in the left-right direction. Further, regarding the specific structure inside the inkjet head shown in FIG. 3A, for example, FIG. 2 and the like described in Japanese Patent Application Laid-Open No. 2012-140017 can be referred to.

Representative examples of the inkjet head are shown in FIGS. 3A and 3B, but in addition to the above, for example, Japanese Patent Application Laid-Open No. 2012-140017, Japanese Patent Application Laid-Open No. 2013-010227, Japanese Patent Application Laid-Open No. 2014-058171 and Japanese Patent Application Laid-Open No. 2014 -097644, JP2015-142979, JP2015-142980, JP2016-002675, JP2016-002682, JP2016-107401, JP2017-109476 An inkjet head having the configuration described in Japanese Patent Application Laid-Open No. 2017-177626 and the like can be appropriately selected and applied.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, the indication of "parts" or "%" is used, but unless otherwise specified, it indicates "parts by mass" or "% by mass".

<< Fabrication of organic EL element >>
[Manufacturing of organic EL element 1]
(1. Preparation of a base material having a gas barrier layer)
Polyethylene naphthalate film (film manufactured by Teijin Film Solutions Co., Ltd., hereinafter abbreviated as PEN) is used as the flexible film constituting the base material, and the surface side on which the anode is formed is described in JP-A-2004-68143. Using the atmospheric pressure plasma discharge treatment apparatus having the above-described configuration, an inorganic gas barrier film made of SiOx was continuously formed on the flexible film so as to have a thickness of 500 nm, and the oxygen permeability was 0. 001mL / m ² · 24hr or less, water vapor permeability was prepared a substrate having the following gas barrier layer 0.001g / m ² · 24hr.

(2. Formation of the first electrode (anode))
ITO (indium tin oxide) having a thickness of 120 nm was formed on the prepared flexible film having a gas barrier property by a sputtering method, and patterned by a photolithography method to form an anode.

The pattern was set so that the light emitting area was 50 mm ² .

(3. Formation of hole injection layer)
The patterned ITO substrate was ultrasonically cleaned with isopropyl alcohol, dried with dry nitrogen gas, and UV ozone washed for 5 minutes. Poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (abbreviated as PEDOT / PSS, manufactured by Heleus, Clevios P JET) was used as an ink composition for forming a hole injection layer on this substrate, as described in FIG. Using the piezo-type inkjet printer head "KM1024i" manufactured by Konica Minolta, which is a piezo-type inkjet printer head having the structure described in FIG. 2, at 40 ° C. according to the manufacturing flow of the organic EL element by the inkjet printing method shown in FIG. A hole-injected layer was formed by injecting the ink onto the first electrode (anodide) under the condition that the layer thickness after drying was 30 nm, and then drying at 200 ° C. for 1 hour.

(4. Formation of hole transport layer)
Konica is a piezo-type inkjet printer head having the structures shown in FIGS. 3A and 3B described above, using an ink composition for forming a hole transport layer having the following composition on the hole injection layer formed on the substrate. Using a piezo inkjet printer head "KM1024i" manufactured by Minolta, injection was performed at 40 ° C. under the condition that the layer thickness after drying was 30 nm according to the manufacturing flow of the organic EL element by the inkjet printing method shown in FIG. Then, it was dried at 160 ° C. for 30 minutes to form a hole transport layer.

<Ink composition for forming a hole transport layer>
Hole transport material 1 (weight average molecular weight Mw = 80000) 2.5 parts by mass Tetralin 500 parts by mass (5. Formation of light emitting layer)
Next, using the ink composition for forming a light emitting layer having the following composition, a piezo inkjet printer head "KM1024i" manufactured by Konica Minolta, which is a piezo inkjet printer head having the structures shown in FIGS. 3A and 3B described above, is used. In accordance with the manufacturing flow of the organic EL element by the inkjet printing method shown in FIG. 2, the organic EL element is injected onto the hole transport layer at 40 ° C. under the condition that the layer thickness after drying is 50 nm, and then at 120 ° C. for 30 minutes. It was dried to form a light emitting layer.

<Ink composition for forming a light emitting layer>
Host compound 1 8.78 parts by mass Phosphorescent light emitting dopant compound D-1 3.01 parts by mass Phosphorescent light emitting dopant compound D-2 0.05 parts by mass Phosphorescent light emitting dopant compound D-3 0.05 parts by mass propylene glycol monomethyl Etheracetate 1000 parts by mass (6. Formation of electron transport layer)
Subsequently, a piezo inkjet printer head "KM1024i" manufactured by Konica Minolta, which is a piezo inkjet printer head having the structures shown in FIGS. 3A and 3B described above, using an ink composition for forming an electron transport layer having the following composition. In accordance with the manufacturing flow of the organic EL element by the inkjet printing method shown in FIG. 2, the film is injected onto the light emitting layer at 40 ° C. under the condition that the layer thickness after drying is 30 nm, and then 30 at 120 ° C. It was dried for minutes to form an electron transport layer.

<Ink composition for forming an electron transport layer>
8-Hydroxyquinolinatolithium 0.3 parts by mass Electrotransport compound M-33 2.7 parts by mass Cesium acetate 0.18 parts by mass 2-hexanol (boiling point: 140 ° C., vapor pressure: 0.35 kPa)
150 parts by mass 2,2,3,3,4,5,5-octafluoro-1-pentanol (boiling point: 142 ° C., vapor pressure: 0.51 kPa, abbreviation: OFPO) 350 parts by mass (7. electrons Formation of injection layer and cathode)
Subsequently, the substrate was attached to the vacuum deposition apparatus without exposure to the atmosphere. In addition, a molybdenum resistance heating boat containing sodium fluoride and potassium fluoride was attached to a vacuum vapor deposition apparatus, the vacuum tank ^{was depressurized to 4 × 10 -5} Pa, and then the boat was energized and heated. Sodium fluoride was vapor-deposited on the electron transport layer at 0.02 nm / sec to form a thin film having a film thickness of 1 nm, and then potassium fluoride was similarly vapor-deposited on the thin film at 0.02 nm / sec. An electron injection layer having a thickness of 1.5 nm was provided.

Subsequently, aluminum was vapor-deposited on the electron injection layer to provide a cathode having a thickness of 100 nm.

(8. Encapsulation and fabrication of organic EL element)
Subsequently, the sealing member was adhered using a commercially available roll laminating device to produce the organic EL element 1.

Specifically, as a sealing member, a polyethylene terephthalate (PET) film (12 μm thickness) is applied to a flexible aluminum foil (manufactured by Toyo Aluminum K.K. Co., Ltd.) with a thickness of 30 μm as an adhesive for dry lamination (two-component reaction type). The one laminated with (urethane-based adhesive) (thickness of the adhesive layer 1.5 μm) was used.

A thermosetting adhesive was uniformly applied to the aluminum surface as a sealing adhesive with a thickness of 20 μm along the adhesive surface (glossy surface) of the aluminum foil using a dispenser. This was dried under a vacuum of 100 Pa or less for 12 hours. Further, the dew point temperature was moved to −80 ° C. or lower and the oxygen concentration was 0.8 ppm in a nitrogen atmosphere, and the mixture was dried for 12 hours or longer to adjust the water content of the sealing adhesive to 100 ppm or lower.

As the thermosetting adhesive, an epoxy-based adhesive in which the following (A) to (C) were mixed was used.

(A) Bisphenol A Diglycidyl Ether (DGEBA)
(B) Dicyanodiamide (DICY)
(C) Epoxy adduct-based curing accelerator As described above, the sealing member is closely adhered and arranged so as to cover the joint between the take-out electrode and the electrode lead, and a crimping roll is used for thick coating conditions and crimping roll temperature. The organic EL element 1 was obtained by tightly sealing at 120 ° C., a pressure of 0.5 MPa, and a device speed of 0.3 m / min.

[Manufacturing of organic EL elements 2-85]
In the production of the organic EL element 1, the types of electron transport materials, the types of fluorine-based solvents, the types of non-fluorine-based solvents, and the composition ratios of the respective solvents that constitute the ink composition for forming the electron transport layer are shown in Tables I to Tables. Organic EL devices 2 to 85 were produced in the same manner except that the combination was changed to that described in III.

Details of each constituent material listed in Tables I to III above are as follows.

(Fluorine solvent)
TFPO: 2,2,3,3-tetrafluoro-1-propanol (boiling point: 109 ° C., vapor pressure: 2.53 kPa)
OFPO: 2,2,3,3,4,5,5-octafluoro-1-pentanol (boiling point: 142 ° C., vapor pressure: 0.51 kPa)
HDFDO: 1H, 1H, 2H, 2H-heptadecafluoro-1-decanol (boiling point: 115 ° C., vapor pressure: 2.66 kPa),
TrF1PO: 3,3,3-trifluoro-1-propanol (boiling point: 100 ° C., vapor pressure: 5.14 kPa (calculated value)),
(Non-fluorine solvent)
MeOPrO: 1-methoxy-2-propanol (boiling point: 120 ° C., vapor pressure: 0.67 kPa)
EGMME: Ethylene glycol monomethyl ether (boiling point: 124 ° C., vapor pressure: 0.80 kPa)
PGMEE: Propylene glycol monoethyl ether (boiling point: 133 ° C., vapor pressure: 0.53 kPa)
Details of the compounds excluding the electron-transporting compounds used in the production of each organic EL device are as follows.

<< Evaluation of ink composition >>
Each of the following evaluations was performed on the ink compositions 1 to 85 used for forming the electron transport layer of the organic EL elements 1 to 85 according to the following method.

[Evaluation of injection stability]
Each ink composition is filled in a piezo inkjet printer head "KM1024i" (number of nozzles: 1024) manufactured by Konica Minolta, which is a piezo inkjet printer head having the structures shown in FIGS. 3A and 3B, and continuously for 1 minute. After injection, the nozzle surface of the inkjet printer head was opened and left for 2 minutes. Next, the ink composition was re-injected from the inkjet printer head (number of nozzles: 1024), the number of nozzles causing nozzle shortage or diagonal ejection due to nozzle clogging was counted, and the injection stability was evaluated according to the following criteria. ..

◯: Nozzle missing or diagonal injection occurred in all nozzles Δ: Weak nozzle missing or diagonal injection occurred in 1 to 5 nozzles, but it was within the practically acceptable range ×: With 6 or more nozzles, missing nozzles and diagonal injections are observed, which is a quality that poses a practical problem [Evaluation of member compatibility]
First, a resin sample for evaluation was prepared. Using "EP300" manufactured by Cemedyne Co., Ltd., which is a two-component mixed epoxy resin, 0.5 g of the main agent and the curing agent are collected and kneaded at a ratio of 1: 1 on a glass substrate having mold releasability. Then, heat curing was carried out in an oven at 40 ° C. for 12 hours to prepare a plate-shaped evaluation resin sample, which was peeled off from the glass substrate, and its mass 1 was measured in the untreated stage.

Next, the above 1 g of the evaluation resin sample was immersed in 50 g of each ink composition, and stored in an oven at 60 ° C. for 7 days in a sealed state. Then, the evaluation resin sample was taken out, thoroughly washed with 2-propanol, dried, and the mass 2 of the evaluation resin sample after the treatment was measured.

Next, the mass change rate (relative value) of the mass 2 of the treated sample when the mass 1 of the untreated sample was set to 100% was obtained, and the member compatibility was evaluated according to the following evaluation criteria. In this evaluation, since the resin sample causes dissolution or swelling by the above treatment, the mass change rate was determined as an absolute value.

⊚: Mass change amount (absolute value) is less than 2.0 mass% ○: Mass change amount (absolute value) is 2.0 mass% or more and less than 5.0 mass% Δ: Mass change rate (Absolute value) is 5.0% by mass or more and less than 10.0% by mass ×: Mass change amount (absolute value) is 10.0% by mass or more [Electronic transport compound (ET material) Solubility]
The electron-transporting compounds constituting each ink composition are mixed with the mixed solvents (solvents A1 and B and B in Tables I and II) constituting the ink composition under the condition that the solid content concentration is 0.8% by mass. Dissolve in solvent A2 (type and composition ratio) at 60 ° C, fill and seal in a glass bottle, store the solution in a dark place at 25 ° C for 24 hours, and then visually observe the dissolution of the solution and use the following criteria. The solubility of the electron-transporting compound in the mixed solvent constituting the ink composition was evaluated according to the above.

◯: No precipitation was observed in the solution and it was clear. Δ: Fine precipitates were observed in the solution, but it was within the practically acceptable range. ×: Preparation Occasionally, electron-transporting compounds do not dissolve, or a large amount of precipitates are observed after storage for 24 hours << Evaluation of organic EL device performance >>
Each of the following evaluations was performed on the organic EL elements 1 to 82 according to the following method.

[Solvent resistance to the lower layer (light emitting layer)]
The ink composition for forming a light emitting layer used for producing each organic EL element is injected onto a glass substrate using an inkjet printer head "KM1024i" under the condition that the layer thickness after drying is 50 nm, and then 120. A sample for evaluation was prepared by drying at ° C. for 30 minutes to form a light emitting layer.

Next, on the light emitting layer of the evaluation sample prepared above, a piezo element capable of heating up to 60 ° C. was formed by using the solvent of the ink composition for forming each electron transport layer used for forming the electron transport layer of each organic EL element. Using an inkjet printer (FUJIFILM Dimatix Inc. DMP-2831) equipped with an inkjet head, the ink was discharged at 25 ° C., and the solvent resistance (rinse resistance) of the lower layer was evaluated by the following method.

The absorbance of the evaluation sample at 250 nm before and after the rinsing treatment was measured using a spectrophotometer [UV-3300] manufactured by Hitachi, Ltd.

Next, the residual ratio (%) of the light emitting layer was obtained from the following formula using the absorbance before and after the rinsing treatment obtained above, and the solvent resistance to the light emitting layer was evaluated according to the following evaluation rank.

Residual rate (%) = (absorbance after rinsing) / (absorbance before rinsing) x 100
◯: Residual rate is 90% or more and no white haze is observed on the shipping layer surface Δ: Residual rate is 80% or more and less than 90%, and weak white haze is observed on a part of the shipping layer surface However, the quality is practically acceptable. ×: Residual rate is less than 80%, or white haze is observed on the entire surface of the shipping layer [Evaluation of external extraction quantum efficiency (EQE)]
Each organic EL element is energized under constant current conditions of room temperature (about 23 ° C.) and ^2.5 mA / cm 2, and the emission brightness (L0) (cd / m ² ) immediately after the start of emission is measured to measure the external intensity. The extraction quantum efficiency (EQE) was calculated.

Here, the emission brightness was measured using a spectral radiance meter CS-2000 (manufactured by Konica Minolta Co., Ltd.), and the external extraction quantum efficiency was determined by obtaining a relative EQE with the organic EL element 8 as 1.00. The external extraction quantum efficiency (EQE) was evaluated according to the following evaluation ranks.

⊚: Relative EQE is 1.20 or more ◯: Relative EQE is 1.05 or more and less than 1.20 Δ: Relative EQE is 0.95 or more and less than 1.05 ×: Relative EQE Is less than 0.95. The results obtained by the above are shown in Tables IV and V.

As is clear from the results shown in Table IV and Table V, the ink composition having a configuration satisfying the conditions specified in the present invention is excellent in injection stability without causing nozzle shortage on the nozzle surface as compared with the comparative example. , It can be seen that the compatibility with the members constituting the nozzle plate (Matecon resistance) and the solubility of the electron-transporting compound are excellent.

Further, the organic EL element of the present invention in which the electron transport layer is formed by the inkjet printing method using the ink composition of the present invention has excellent solvent resistance and external extraction quantum efficiency without elution of the light emitting layer provided in the lower layer. It can be seen that (EQE) is high.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to obtain an ink composition suitable for an inkjet printing method having excellent ejection stability and member compatibility in an inkjet head, and using the ink composition, solvent resistance to an lower layer during production of an organic EL element It can be applied to an organic EL element capable of obtaining an organic EL element having excellent and high external quantum efficiency (EQE).

1 Organic EL element 2 Base material 3 First electrode (anode)
4 Hole injection layer 5 Hole transport layer 6 Light emitting layer 7 Electron transport layer 8 Electron injection layer 9 Second electrode (cathode)
10 Extraction electrode (1st electrode)
11 Extraction electrode (second electrode)
12 Adhesive layer for sealing 13 Sealing base material 30, 100 Inkjet head 31, 39 Pump 32 Filter 33 Piping branch 34 Waste liquid tank 35 Control unit 36, 37, 38A, 38B Tank 56 Housing 57 Cap receiving plate 59 Cover member 61 Nozzle plate 62 Cap receiving plate mounting part 68 Mounting hole 71 Nozzle opening 81a 1st join 81b 2nd joint 82 3rd joint LA light emitting area U organic functional layer unit

Claims (10)

An ink composition for inkjet used for forming an organic layer A constituting an organic electroluminescence element.
It contains at least an organic functional material forming the organic layer A, at least one fluorine-based solvent, and a non-fluorine-based solvent having a boiling point of 99 ° C. or higher at 1 atm (101.3 kPa). ,
An ink composition, wherein the at least one fluorine-based solvent has the lowest vapor pressure at 25 ° C. as compared with all non-fluorine-based solvents in which 5% by mass or more is present in the ink composition. The ink composition according to claim 1, wherein the fluorine-based solvent contains two or more types of fluorine-based solvents having different vapor pressures at 25 ° C. It contains at least two types of fluorine-based solvent A1 and fluorine-based solvent A2, and non-fluorine-based solvent B, and the order of the vapor pressures of each of the above solvents at 25 ° C. satisfies the condition specified by the following relational expression 1. The ink composition according to claim 1 or 2, which is characterized.
(Relational formula 1)
Vapor pressure Fluorine solvent A2 <Non-fluorine solvent B <Fluorine solvent A1 The ink composition according to claim 3, wherein the difference in boiling points between the two types of fluorine-based solvent A1 and the fluorine-based solvent A2 is 20 ° C. or higher at 1 atm (101.3 kPa). The ink composition according to any one of claims 1 to 4, wherein the total amount of the fluorine-based solvent with respect to the total amount of the solvent of the ink composition is 51% by mass or more. The ink composition according to any one of claims 1 to 5, wherein the organic functional material constituting the organic layer A is an electron transporting material or an electron injecting material. The ink composition according to claim 6, wherein the organic functional material constituting the organic layer A is an electron transporting material. A method for manufacturing an organic electroluminescence device having an organic layer.
An organic electroluminescence device, which comprises forming at least one organic layer A using the ink composition according to any one of claims 1 to 7 by using an inkjet printing method. Production method. The organic electroluminescence element according to claim 8, wherein the organic layer A is formed by using the ink composition on the organic layer B containing an organic compound having a molecular weight in the range of 700 to 2000. Production method. An organic electroluminescence device having an organic layer formed by using the ink composition according to any one of claims 1 to 7.

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