JP2009164113A - Method of manufacturing organic electroluminescent element, and organic electroluminescent display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing an organic electroluminescent element with an organic layer formed by a wet deposition method in which an element of a long life can be obtained. <P>SOLUTION: In the method of manufacturing an organic electroluminescent element having a hole injection layer and/or a hole transport layer and a light emitting layer between a positive electrode and a negative electrode, a first heating step in which a composition containing a hole injection material and/or a hole transport material and a solvent is deposited and a deposited membrane is heated in a temperature of boiling point of the solvent or higher, a first cooling step of cooling the membrane, and a second heating step of heating the membrane are followed in the above order to form the hole injection layer and/or the hole transport layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing an organic electroluminescent element used for a display, illumination, or the like. Specifically, the present invention provides a method for producing an organic electroluminescent device having an organic layer formed by a wet film-forming method, whereby a long-life device can be obtained.

  Since the announcement of Kodak's stacked organic electroluminescence (EL) element using vacuum deposition, organic EL displays have been actively developed and are now in practical use. It's getting on.

  In such a stacked organic electroluminescent device, a plurality of organic layers (such as a light emitting layer, a hole injection layer, a hole transport layer, and an electron transport layer) are stacked between an anode and a cathode. In many cases, these organic layers are formed by vacuum-depositing organic layer materials such as low molecular weight dyes. However, it is difficult to obtain a uniform and defect-free film by the vacuum vapor deposition method, and it takes a long time to form several organic layers, and thus there is a problem in terms of device manufacturing efficiency.

  On the other hand, technologies for forming a plurality of organic layers of a stacked organic electroluminescent element by a wet film forming method have been developed (Patent Documents 1 and 2). However, in the wet film forming method, it is known that the coating process and the drying process greatly affect the performance of the element, and various studies have been made heretofore.

  For example, with respect to the drying process, those having a one-step heating process (Patent Document 3) and those having a step-wise heating process (Patent Document 4) have been developed in the formation process of the hole injection layer / transport layer. .

JP 04-002096 A International Publication No. 2006/095539 Pamphlet JP 2006-278651 A JP 2003-282248 A

  However, the conventional method has a problem that light emission unevenness is likely to occur, the element is often deteriorated significantly, and the lifetime is not long.

  The present invention has been made in view of the above problems. That is, an object of the present invention is to provide a method for producing an organic electroluminescent device having an organic layer formed by a wet film forming method, in which a long-life device is obtained.

In the present invention, an organic electroluminescence device having a hole injection layer and / or a hole transport layer and a light emitting layer formed by a wet film forming method has a stepwise heating process and a cooling process as compared with the prior art. It is characterized by.
That is, a first heating step for removing the solvent by heating at a temperature equal to or higher than the boiling point, a cooling step for alleviating the internal distortion of the film due to heating, and a second heating for obtaining film homogeneity By performing the process, a stable and long-life element can be obtained.

  As a result of intensive studies by the present inventors, in an organic electroluminescence device having a hole injection layer and / or a hole transport layer and a light emitting layer formed by a wet film forming method, a specific heating step and cooling step are performed. It has been found that the above problems can be solved by having the present invention, and the present invention has been achieved.

  That is, the gist of the present invention is a method for producing an organic electroluminescent device having a hole injection layer and / or a hole transport layer and a light emitting layer between an anode and a cathode, wherein the hole injection material and / or Or forming a composition containing a hole transport material and a solvent, and heating the formed film at a temperature equal to or higher than the boiling point of the solvent; a first cooling step for cooling; and The present invention resides in a method for manufacturing an organic electroluminescent element, wherein the hole injection layer and / or the hole transport layer are formed by passing through a second heating step in this order.

  At this time, in the second heating step, it is preferable to heat at a temperature rising rate of 3 ° C./second or more and 150 ° C./second or less (Claim 2).

  Moreover, it is also preferable that the difference between the heating temperature of the first heating step and the cooling temperature of the first cooling step is 100 ° C. or more.

  Further, the boiling point of the solvent is preferably 110 ° C. or higher and 300 ° C. or lower (claim 4).

  It is also preferable that the light emitting layer is formed as a layer made of a low molecular compound by a wet film forming method.

Moreover, it is preferable that this hole transport material is a thermally crosslinkable compound (Claim 6).
Another subject matter of the present invention lies in an organic EL display comprising the organic electroluminescent element obtained by the above-described method for producing an organic electroluminescent element (claim 7).

  According to the method for manufacturing an organic electroluminescent element of the present invention, even when a wet film forming method is used, organic electroluminescence with a long life and low driving voltage can be obtained by using a stepwise heating process and a cooling process. An element is obtained.

  Hereinafter, the present invention will be described in detail, but the present invention is not limited to the following examples, and various modifications can be made without departing from the spirit of the present invention.

The present invention relates to a method for producing an organic electroluminescent device having a hole injection layer and / or a hole transport layer and a light emitting layer between an anode and a cathode, wherein the hole injection layer and the positive electrode are formed by a specific method. A hole transport layer is formed.
Specifically, the method includes a film forming step of forming a composition containing a hole injection material and / or a hole transporting material and a solvent, and a drying step of drying the formed film.
Here, the drying process includes a first heating process for heating the formed film at a temperature equal to or higher than the boiling point of the solvent, a first cooling process for cooling, and a second heating process for heating. Is. In addition, as long as the effect of this invention is not impaired remarkably, you may perform another process.

  Hereinafter, a hole injection material and / or a hole transport material and a composition containing a solvent will be described first, and then a film forming step and a drying step will be described.

[1. A composition containing a hole injection material and / or a hole transport material and a solvent]
An organic electroluminescent device manufactured by the method for manufacturing an organic electroluminescent device of the present invention (organic electroluminescent device of the present invention) is a composition containing a hole injection material and a solvent (hereinafter referred to as “for hole injection layer”). The composition may be referred to as a “composition”.) And / or a composition containing a hole transport material and a solvent (hereinafter, referred to as “hole transport layer composition”). At least a hole transport layer formed from.

  Each of the hole injection material and the hole transport material has at least a hole transporting compound used for a hole injection layer, a hole transport layer, or the like of the organic electroluminescent element. The hole transporting compound may be a high molecular compound or a low molecular compound as long as the effects of the present invention are not significantly impaired. Hereinafter, the composition for hole injection layers and the composition for hole transport layers will be described.

<1-1. Composition for Hole Injection Layer>
In the method for manufacturing a hole injection layer according to the present invention, the hole injection layer is formed by a wet film formation method.
When forming a hole injection layer by a wet film formation method, a hole injection material and a solvent (a solvent for a hole injection layer) are mixed to prepare a composition for a hole injection layer. The composition is applied onto a layer corresponding to the lower layer of the hole injection layer (usually an anode) by an appropriate technique, formed into a film, and dried to form the hole injection layer.

In this case, the hole injection layer formed from the composition for hole injection layer may be formed as a layer containing the compound contained in the composition for hole injection layer as it is. It may be a layer containing a compound or the like obtained by reaction of a compound contained in.
The organic electroluminescent device of the present invention may have a configuration in which the hole injection layer is omitted. However, when the hole injection layer is omitted, the organic electroluminescent element of the present invention has a hole transport layer. When the hole transport layer is produced by the method for producing a hole transport layer according to the present invention, the hole injection layer may be formed by other methods. For example, it may be formed by a vacuum deposition method.

<1-1-1. Hole injection material>
In the present invention, the hole injection material is a material contained in the hole injection layer. Alternatively, the hole injection layer may be formed by the reaction of the material. Furthermore, the hole injection material is not particularly limited as long as it can form a hole injection layer by a wet film formation method.
Usually, examples of the hole injection material include a hole transporting compound and an electron accepting compound. Moreover, you may have another component. The hole transporting compound may be a high molecular compound or a low molecular compound. Hereinafter, these hole injection materials will be described.

<1-1-1-1. High molecular weight hole transport compound>
The kind of the hole transporting compound used as the hole injecting material is arbitrary as long as the effects of the present invention are not significantly impaired. However, among them, a polymer having a hole transporting property (a high molecular weight hole transporting compound, hereinafter referred to as “hole transporting polymer” as appropriate) is preferable, and an ionization potential of 4.5 eV to 5.5 eV is particularly preferable. It is preferable that it is a compound which has. The ionization potential is defined as the energy required to emit electrons at the HOMO (highest occupied molecular orbital) level of a material to the vacuum level, and can be measured directly by photoelectron spectroscopy or electrochemically. It is also obtained by correcting the oxidized potential with respect to the reference electrode. In the case of the latter method, for example, when a saturated sweet potato electrode (SCE) is used as a reference electrode, it is represented by the following formula (“Molecular Semiconductors”, Springer-Verlag, 1985, pp. 98).
Ionization potential = oxidation potential (vs. SCE) + 4.3 eV

  Examples of the hole transporting polymer include aromatic amine compounds, phthalocyanine derivatives, porphyrin derivatives, oligothiophene derivatives, and the like. Of these, aromatic amine compounds are preferred from the viewpoints of amorphousness, solubility in solvents, and visible light transmittance.

Of the aromatic amine compounds, aromatic tertiary amine compounds are particularly preferable. In addition, the aromatic tertiary amine compound here is a compound having an aromatic tertiary amine structure, and includes a compound having a group derived from an aromatic tertiary amine.
The type of the aromatic tertiary amine compound is not particularly limited, but a polymer compound having a weight average molecular weight of 1,000 or more from the viewpoint of heat resistance and a weight average molecular weight of 1,000,000 or less is more preferable from the viewpoint of solubility.

(First example of aromatic tertiary amine compound)
Preferable examples of the aromatic tertiary amine polymer compound include a polymer compound having a repeating unit represented by the following formula (I).

In the formula (I), Ar ¹ and Ar ² each independently represent an aromatic hydrocarbon group which may have a substituent or an aromatic heterocyclic group which may have a substituent. . Ar ^{3 to} Ar ⁵ each independently represents a divalent aromatic hydrocarbon group which may have a substituent or a divalent aromatic heterocyclic group which may have a substituent. . X represents a linking group selected from the following linking group group X1.

Linking group group X1:

In the above formula, Ar ^{11 to} Ar ²⁸ each independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent. R ¹ and R ² each independently represents a hydrogen atom or an arbitrary substituent.

In the formula (I), as Ar ^{1 to} Ar ⁵ and Ar ^{11 to} Ar ²⁸ , monovalent or divalent groups derived from any aromatic hydrocarbon ring or aromatic heterocyclic ring are applicable. That is, a monovalent group can be applied to each of Ar ¹ , Ar ² , Ar ¹⁶ , Ar ^21, and Ar ²⁶ , and Ar ^{3 to} Ar ⁵ , Ar ^{11 to} Ar ¹⁵ , Ar ^{17 to} Ar ²⁰ , Ar ²² to A divalent group can be applied to each of Ar ²⁵ , Ar ^27, and Ar ²⁸ . These may be the same or different from each other. Moreover, you may have arbitrary substituents.

  Examples of the aromatic hydrocarbon ring include a 5- or 6-membered monocyclic ring or a 2-5 condensed ring. Specific examples thereof include a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluoranthene ring, and fluorene ring.

  Examples of the aromatic heterocycle include a 5- or 6-membered monocyclic ring or a 2-4 condensed ring. Specific examples thereof include furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring. , Thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzoisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline Ring, cinolin ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, quinazolinone ring, azulene ring and the like.

Ar ^{3 to} Ar ⁵ , Ar ^{11 to} Ar ¹⁵ , Ar ^{17 to} Ar ²⁰ , Ar ^{22 to} Ar ²⁵ , Ar ²⁷ , Ar ²⁸ may be one or more types of aromatic hydrocarbon rings exemplified above. And / or two or more divalent groups derived from an aromatic heterocycle may be linked and used.

Further, the groups derived from the aromatic hydrocarbon rings and / or aromatic heterocycles of Ar ^{1 to} Ar ⁵ and Ar ^{11 to} Ar ²⁸ may have further substituents unless they significantly disturb the formation of the coating film. Good. The molecular weight of the substituent is usually 400 or less, and preferably 250 or less from the viewpoint of solubility. The type of the substituent is not particularly limited, and examples thereof include one or more selected from the following substituent group W. In addition, as for a substituent, 1 piece may be substituted independently and 2 or more may be substituted by arbitrary combinations and ratios.

[Substituent group W]
An alkyl group having usually 1 or more, usually 10 or less, preferably 8 or less, such as a methyl group or an ethyl group; an alkenyl group having 2 or more, usually 11 or less, preferably 5 or less carbon atoms, such as a vinyl group. An alkynyl group having usually 2 or more, usually 11 or less, preferably 5 or less, such as an ethynyl group; an alkoxy having a carbon number of usually 1 or more, usually 10 or less, preferably 6 or less, such as a methoxy group or an ethoxy group; A group; an aryloxy group such as a phenoxy group, a naphthoxy group, a pyridyloxy group, etc., usually 4 or more, preferably 5 or more, usually 25 or less, preferably 14 or less; a carbon such as a methoxycarbonyl group or an ethoxycarbonyl group An alkoxycarbonyl group having a number of usually 2 or more, usually 11 or less, preferably 7 or less; a dimethylamino group, a diethylamino group or the like, and usually having 2 or more carbon atoms Usually 20 or less, preferably 12 or less dialkylamino group; diphenylamino group, ditolylamino group, N-carbazolyl group, etc., and usually diarylamino having 10 or more carbon atoms, preferably 12 or more, usually 30 or less, preferably 22 or less Group: an arylalkylamino group having 6 or more carbon atoms, preferably 7 or more, usually 25 or less, preferably 17 or less, such as a phenylmethylamino group; an acetyl group, a benzoyl group or the like, and usually having 2 or more carbon atoms, Usually an acyl group of 10 or less, preferably 7 or less; a halogen atom such as a fluorine atom or a chlorine atom; a haloalkyl group having a carbon number of usually 1 or more, usually 8 or less, preferably 4 or less, such as a trifluoromethyl group; An alkylthio group having 1 to 10 carbon atoms, preferably 6 or less, preferably 6 or less; An arylthio group having usually 4 or more, preferably 5 or more, usually 25 or less, preferably 14 or less, such as a ruthio group, a naphthylthio group, or a pyridylthio group; Or more, preferably 3 or more, usually 33 or less, preferably 26 or less silyl group; trimethylsiloxy group, triphenylsiloxy group, etc., the carbon number is usually 2 or more, preferably 3 or more, usually 33 or less, preferably 26 or less. A siloxy group; a cyano group; an aromatic hydrocarbon ring group having usually 6 or more, usually 30 or less, preferably 18 or less, such as a phenyl group or a naphthyl group; a carbon number such as a thienyl group or a pyridyl group. An aromatic heterocyclic group of 3 or more, preferably 4 or more, usually 28 or less, preferably 17 or less.

Among those described above, Ar ¹ and Ar ² are 1 derived from a benzene ring, a naphthalene ring, a phenanthrene ring, a thiophene ring, and a pyridine ring from the viewpoint of the solubility, heat resistance, and hole injection / transport properties of the polymer compound. Is more preferably a phenyl group or a naphthyl group.

Among the above, Ar ^{3 to} Ar ⁵ are divalent derived from a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene ring in terms of heat resistance and hole injection / transport properties including a redox potential. Group is preferable, and a phenylene group, a biphenylene group, and a naphthylene group are more preferable.

In the formula (I), as R ¹ and R ² , a hydrogen atom or an arbitrary substituent is applicable. These may be the same or different from each other. Examples of applicable substituents include alkyl groups, alkenyl groups, alkynyl groups, alkoxy groups, silyl groups, siloxy groups, aromatic hydrocarbon groups, and aromatic heterocyclic groups. Specific examples thereof include the groups exemplified above in the substituent group W.

Among the polymer compounds having a repeating unit represented by the formula (I), a polymer compound having a repeating unit represented by the following formula (I ′) is particularly preferable because of its very high hole injection / transport properties.

In the formula (I ′), R ^{41 to} R ⁴⁵ each independently represents an arbitrary substituent. Specific examples of the substituents of R ^{41 to} R ⁴⁵ are the same as the substituents that Ar ^{1 to} Ar ⁵ of formula (I) may have (that is, the substituents described in [Substituent Group W]). It is. In formula (I ′), p and q each independently represent an integer of 0 to 5, and r, s, and t each independently represent an integer of 0 to 4. Y ′ represents a linking group selected from the following linking group group Y2.

In the above formulas, Ar ^{31 to} Ar ³⁷ each independently represents an aromatic hydrocarbon ring which may have a substituent, or a monovalent or divalent group derived from an aromatic heterocyclic ring. Specific examples of Ar ^{31 to} Ar ³⁷ are the same as Ar ^{1 to} Ar ⁵ described above. That is, Ar ^{31 to} Ar ³⁵ and Ar ³⁷ are the same as Ar ^{3 to} Ar ^5, and Ar ³⁶ is the same as Ar ¹ and Ar ² . Moreover, the substituent which may have is the same as said Ar < ¹ > -Ar < ⁵ >.

  The preferred specific examples of the repeating unit represented by the formula (I) or the formula (I ′) that can be used in the present invention are shown below, but the present invention is not limited thereto.

(Second example of aromatic tertiary amine compound)
In addition, preferred examples of other aromatic tertiary amine polymer compounds include polymer compounds containing a repeating unit represented by the following formula (III-1) and / or formula (III-2).

In formulas (III-1) and (III-2), Ar ⁴⁵ , Ar ⁴⁷ and Ar ⁴⁸ each independently have an aromatic hydrocarbon group which may have a substituent, or a substituent. Represents an aromatic heterocyclic group which may be Ar ⁴⁴ and Ar ⁴⁶ each independently represent a divalent aromatic hydrocarbon group which may have a substituent, or a divalent aromatic heterocyclic group which may have a substituent. R ^{41 to} R ⁴³ each independently represents a hydrogen atom or an arbitrary substituent.

Specific examples of Ar ⁴⁵ , Ar ⁴⁷ and Ar ⁴⁸ , and Ar ⁴⁴ and Ar ⁴⁶ , preferred examples, examples of substituents that may be included, and examples of preferred substituents are Ar ²¹ and Ar ²² , and Ar, respectively. ^{23 to} Ar ²⁵ .

R ^{41 to} R ⁴³ are preferably a hydrogen atom or a substituent described in [Substituent group W], and more preferably a hydrogen atom, an alkyl group, an alkoxy group, an amino group, an aromatic hydrocarbon group, an aromatic group. Group hydrocarbon group.

  Specific examples of the repeating unit represented by the formulas (III-1) and (III-2) suitable for the present invention are shown below, but are not limited thereto.

  Moreover, as a preferable example of the aromatic amine polymer compound capable of obtaining a more homogeneous film, a polymer compound having the following repeating unit may be mentioned. Therefore, the aromatic tertiary amine compounds exemplified as the preferred high molecular weight hole transporting compounds also particularly preferably have the following repeating units. However, the present invention is not limited to these examples.

(Characteristics of aromatic amine compounds)
The aromatic amine compound may be a homopolymer composed of any one of the various repeating units described above, or a copolymer containing two or more kinds in any combination and ratio. Also good. In the latter case, the form of the copolymer may be block copolymerization or random copolymerization.

Moreover, the hole transportable compound used as a hole injection material may be used individually by 1 type, and may be used two or more types by arbitrary combinations and a ratio.
Therefore, the hole transporting polymer may be used alone, or two or more may be used in any combination and ratio.
Further, only one of the high molecular weight hole transporting compound and the low molecular weight hole transporting compound (described later) may be used, or both may be used in combination.

  The weight average molecular weight of the hole transporting polymer used as the material of the hole injection layer is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 100 or more, preferably 500 or more, more preferably 1000 or more, Preferably it is 1,000,000 or less. If the weight average molecular weight is too small, the solvent used for the layer laminated thereon may be limited. On the other hand, if the weight average molecular weight is too large, the film formability of the hole injection layer may be impaired.

  The ratio of the hole transporting polymer in the hole injection layer is arbitrary as long as the effects of the present invention are not significantly impaired. % By weight or more, preferably 30% by weight or more, and usually 99.9% by weight or less, preferably 99% by weight or less. If the ratio of the hole transporting polymer is too small, the movement of holes mainly involves intermolecular movement, and the film components may be significantly impaired. In addition, when using together 2 or more types of hole transportable polymers, it is preferable to make these total content contain in the said range.

<1-1-1-2. Electron-accepting compound>
The kind of the electron accepting compound used as the material for the hole injection layer is arbitrary as long as the effects of the present invention are not significantly impaired. Examples thereof include onium salts substituted with an organic group such as 4-isopropyl-4′-methyldiphenyliodonium tetrakis (pendafluorophenyl) borate and triphenylsulfonium tetrafluoroborate; No. 251067), high-valence inorganic compounds such as ammonium peroxodisulfate; cyano compounds such as tetracyanoethylene; aromatic boron compounds such as tris (pendafluorophenyl) borane (JP-A-2003-31365); fullerene derivatives ; Iodine etc. are mentioned.

  Of the above compounds, an onium salt substituted with an organic group is preferable in terms of having strong oxidizing power, and an inorganic compound having a high valence is preferable, and an onium salt substituted with an organic group in terms of being soluble in various solvents, A cyano compound and an aromatic boron compound are preferable. Furthermore, an onium salt substituted with an organic group is particularly preferable from the viewpoint of achieving both strong oxidizing power and high solubility, and is preferably a compound represented by the following formulas (II-1) to (II-3).

In the above formulas (II-1) to (II-3), R ¹¹ , R ²¹ and R ³¹ each independently represents an organic group bonded to A ^{1 to} A ³ via a carbon atom. R ¹² , R ²² , R ²³ and R ^{32 to} R ³⁴ each independently represent an arbitrary group. Two or more adjacent groups among R ^{11 to} R ³⁴ may be bonded to each other to form a ring. A ^{1 to} A ³ are all long-period periodic tables (hereinafter, unless otherwise specified, the term “periodic table” refers to the long-period periodic table) elements after the third period A ¹ represents an element belonging to Group 17 of the periodic table, A ² represents an element belonging to Group 16 of the periodic table, and A ³ represents an element belonging to Group 15 of the periodic table. Z ₁ ^{n1- to} Z ₃ ^n3- each independently represents a counter anion. n _{1 to} n ₃ each independently represent the ionic value of the counter anion.

In the above formulas (II-1) to (II-3), R ¹¹ , R ²¹ and R ³¹ each independently represents an organic group bonded to A ^{1 to} A ³ via a carbon atom. Accordingly, the type of R ¹¹ , R ²¹ , and R ³¹ is not particularly limited as long as the effect of the present invention is not significantly impaired as long as it is an organic group having a carbon atom at the bonding portion with A ^{1 to} A ^3. .

The molecular weights of R ¹¹ , R ²¹ , and R ³¹ are each a value including the substituent, and are usually 1000 or less, preferably 500 or less.
Preferred examples of R ¹¹ , R ²¹ , and R ³¹ include an alkyl group, an alkenyl group, an alkynyl group, an aromatic hydrocarbon group, and an aromatic heterocyclic group from the viewpoint of delocalizing positive charges. Among them, an aromatic hydrocarbon group or an aromatic heterocyclic group is preferable because it delocalizes positive charges and is thermally stable.

  The alkyl group includes, for example, a linear, branched or cyclic alkyl group having a carbon number of usually 1 or more and usually 12 or less, preferably 6 or less. Specific examples include methyl group, ethyl group, n-propyl group, 2-propyl group, n-butyl group, isobutyl group, tert-butyl group, cyclohexyl group and the like.

  Examples of the alkenyl group include those having usually 2 or more, usually 12 or less, preferably 6 or less carbon atoms. Specific examples include a vinyl group, an allyl group, and a 1-butenyl group.

  Examples of the alkynyl group include those having usually 2 or more, usually 12 or less, preferably 6 or less. Specific examples include ethynyl group and propargyl group.

  Examples of the aromatic hydrocarbon group include a monovalent group derived from a 5- or 6-membered monocyclic ring or a 2 to 5 condensed ring, and a group in which a positive charge is delocalized on the group. . Specific examples thereof include monovalent groups derived from a benzene ring, naphthalene ring, anthracene ring, phenanthrene ring, perylene ring, tetracene ring, pyrene ring, benzpyrene ring, chrysene ring, triphenylene ring, acenaphthene ring, fluorene ring, and the like. Can be mentioned.

  Examples of the aromatic heterocyclic group include a monovalent group derived from a 5- or 6-membered monocyclic ring or a 2-4 condensed ring, and a group in which a positive charge is delocalized on the group. . Specific examples thereof include furan ring, benzofuran ring, thiophene ring, benzothiophene ring, pyrrole ring, pyrazole ring, triazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, Pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring, benzisoxazole ring, benzisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline And monovalent groups derived from a ring, an isoquinoline ring, a sinoline ring, a quinoxaline ring, a phenanthridine ring, a benzimidazole ring, a perimidine ring, a quinazoline ring, a quinazolinone ring, an azulene ring, and the like.

In the above formulas (II-1) to (II-3), R ¹² , R ²² , R ²³ , and R ^{32 to} R ³⁴ each independently represent an arbitrary substituent. Therefore, the types of R ¹² , R ²² , R ²³ , and R ^{32 to} R ³⁴ are not particularly limited as long as the effects of the present invention are not significantly impaired.
The molecular weights of R ¹² , R ²² , R ²³ and R ^{32 to} R ³⁴ are values including the substituents, and are usually 1000 or less, preferably 500 or less.

Examples of R ¹² , R ²² , R ²³ , and R ^{32 to} R ³⁴ include alkyl group, alkenyl group, alkynyl group, aromatic hydrocarbon group, aromatic heterocyclic group, amino group, alkylamino group, arylamino Group, acylamino group, alkoxy group, aryloxy group, acyl group, alkoxycarbonyl group, aryloxycarbonyl group, alkylcarbonyloxy group, alkylthio group, arylthio group, sulfonyl group, alkylsulfonyl group, arylsulfonyl group, sulfonyloxy group cyano Group, hydroxyl group, thiol group, silyl group and the like.

Among them, like R ¹¹ , R ^21, and R ³¹ , an organic group having a carbon atom in the bonding portion with A ^{1 to} A ³ is preferable from the viewpoint of high electron acceptability. Examples include an alkyl group, an alkenyl group, Alkynyl groups, aromatic hydrocarbon groups, and aromatic heterocyclic groups are preferred. In particular, an aromatic hydrocarbon group or an aromatic heterocyclic group is preferable because it has a large electron accepting property and is thermally stable.

As described above, the groups exemplified as R ¹¹ , R ²¹ , R ³¹ , R ¹² , R ²² , R ²³ , and R ^{32 to} R ³⁴ may be further substituted with other substituents. The type of the substituent is not particularly limited, and examples thereof include a halogen atom in addition to the groups exemplified as R ¹¹ , R ²¹ , R ³¹ , R ¹² , R ²² , R ²³ , and R ^{32 to} R ³⁴ . A cyano group, a thiocyano group, a nitro group, etc. are mentioned.

  Among these, an alkyl group, an alkenyl group, an alkynyl group, an alkoxy group, an aryloxy group, an aromatic hydrocarbon group, and an aromatic heterocyclic group are preferable from the viewpoint of not hindering heat resistance and electron accepting property. In addition, the substituent to be further substituted may be substituted with only one, or two or more may be substituted with any combination and ratio.

In the formulas (II-1) to (II-3), two or more adjacent groups out of R ^{11 to} R ³⁴ may be bonded to each other to form a ring.

In formulas (II-1) to (II-3), A ^{1 to} A ³ are all elements after the third period (third to sixth periods) of the periodic table, and A ¹ is the element of the periodic table. An element belonging to Group 17 is represented, A ² represents an element belonging to Group 16 of the periodic table, and A ³ represents an element belonging to Group 15 of the periodic table.

Among these, from the viewpoint of electron acceptability and availability, elements before the fifth period (third to fifth periods) of the periodic table are preferable. That is, A ¹ is preferably any ^one of an iodine atom, a bromine atom, and a chlorine atom, A ² is preferably any one of a tellurium atom, a selenium atom, and a sulfur atom, and A ³ is preferably an antimony atom, an arsenic atom, Any of the phosphorus atoms is preferred.

In particular, from the viewpoint of electron acceptability and compound stability, a compound in which A ¹ in formula (II-1) is a bromine atom or an iodine atom, or A ² in formula (II-2) is a selenium atom or a sulfur atom. A certain compound is preferable, and among them, a compound in which A ¹ in Formula (II-1) is an iodine atom is particularly preferable.

In formulas (II-1) to (II-3), Z ₁ ^{n1 to} Z ₃ ⁿ³ each independently represent a counter anion. The type of the counter anion is not particularly limited, and may be a monoatomic ion or a complex ion. However, the larger the size of the counter anion, the more the negative charge is delocalized, and the positive charge is also delocalized thereby increasing the electron accepting ability. Therefore, the complex ion is preferable to the monoatomic ion.

In formulas (II-1) to (II-3), n _{1 to} n ₃ are each independently any positive integer corresponding to the ionic value of the counter anion Z ₁ ^{n1 to} Z ₃ ⁿ³ . The values of n _{1 to} n ₃ are not particularly limited, but all are preferably 1 or 2, and particularly preferably 1.

Specific examples of Z ₁ ^{n1- to} Z ₃ ^n3- include hydroxide ions, fluoride ions, chloride ions, bromide ions, iodide ions, cyanide ions, nitrate ions, nitrite ions, sulfate ions, sulfite. Ion, perchlorate ion, perbromate ion, periodate ion, chlorate ion, chlorite ion, hypochlorite ion, phosphate ion, phosphite ion, hypophosphite ion, borate ion , Isocyanate ion, hydrosulfide ion, tetrafluoroborate ion, hexafluorophosphate ion, hexachloroantimonate ion; carboxylate ion such as acetate ion, trifluoroacetate ion, benzoate ion; methanesulfonate ion, trifluoro Sulfonate ions such as methane sulfonate ion; methoxy ions, t-butoxy ions, etc. Kokishiion and the like.

In particular, the counter anions Z ₁ ^{n1 to} Z ₃ ⁿ³ are preferably complex ions represented by the following formulas (II-4) to (II-6) from the viewpoint of stability of the compound and solubility in a solvent. In view of the large size, the negative charge is delocalized, and the positive charge is also delocalized to increase the electron accepting ability. Therefore, a complex ion represented by the following formula (II-6) is more preferable.

In formulas (II-4) and (II-6), E ¹ and E ³ each independently represents an element belonging to Group 13 of the periodic table. Of these, a boron atom, an aluminum atom, and a gallium atom are preferable, and a boron atom is preferable from the viewpoint of stability of the compound and ease of synthesis and purification.

In formula (II-5), E ² represents an element belonging to Group 15 of the periodic table. Among these, a phosphorus atom, an arsenic atom and an antimony atom are preferable, and a phosphorus atom is preferable from the viewpoint of stability of the compound, ease of synthesis and purification, and toxicity.

  In the formulas (II-4) and (II-5), X represents a halogen atom such as a fluorine atom, a chlorine atom, or a bromine atom, and is a fluorine atom in terms of stability of the compound, ease of synthesis and purification, A chlorine atom is preferable, and a fluorine atom is particularly preferable.

In formula (II-6), Ar ^{61 to} Ar ⁶⁴ each independently represents an aromatic hydrocarbon group or an aromatic heterocyclic group. Examples of the aromatic hydrocarbon group and the aromatic heterocyclic group are the same as those exemplified above for R ¹¹ , R ²¹ , and R ³¹ , derived from a 5- or 6-membered monocyclic ring or a 2-5 condensed ring These are monovalent groups.
Among these, a monovalent group derived from a benzene ring, a naphthalene ring, a pyridine ring, a pyrazine ring, a pyridazine ring, a pyrimidine ring, a triazine ring, a quinoline ring, or an isoquinoline ring is preferable from the viewpoint of stability and heat resistance of the compound.

The aromatic hydrocarbon group and aromatic heterocyclic group exemplified as Ar ^{61 to} Ar ⁶⁴ may be further substituted with another substituent unless the effects of the present invention are significantly impaired. The type of the substituent is not particularly limited, and any substituent can be applied, but an electron-withdrawing group is preferable.

Especially, it is more preferable that at least one group out of Ar ^{61 to} Ar ⁶⁴ has one or two or more fluorine atoms or chlorine atoms as a substituent. In particular, it is particularly a perfluoroaryl group in which all the hydrogen atoms of Ar ^{61 to} Ar ⁶⁴ are substituted with fluorine atoms from the viewpoint of efficiently delocalizing negative charges and having an appropriate sublimation property. preferable. Specific examples of the perfluoroaryl group include a pentafluorophenyl group, a heptafluoro-2-naphthyl group, and a tetrafluoro-4-pyridyl group.
In addition, as for the said substituent, only one may be substituted and two or more may be substituted by arbitrary combinations and ratios.

  The formula amount of the complex ions represented by the formulas (II-4) to (II-6) is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 100 or more, preferably 300 or more, more preferably 400 or more. Moreover, it is usually 5000 or less, preferably 3000 or less, more preferably 2000 or less. If the formula amount of the complex ion is too small, delocalization of the positive charge and the negative charge is insufficient, so that the electron accepting ability may be decreased, and if the formula amount of the complex ion is too large, The compound itself may interfere with charge transport.

Specific examples of complex ions represented by formulas (II-4) to (II-6) are shown below, but the present invention is not limited to these.

  As the material for the hole injection layer, any one of the various electron-accepting compounds described above may be used alone, or two or more may be used in any combination and ratio. When two or more kinds of electron-accepting compounds are used, two or more kinds of electron-accepting compounds corresponding to any one of the formulas (II-1) to (II-3) may be combined. Two or more electron-accepting compounds corresponding to different formulas may be combined.

  The content of the electron-accepting compound in the hole-injecting layer is arbitrary as long as the effects of the present invention are not significantly impaired. However, in terms of the diffusion of the electron-accepting compound, the content is usually 0. .1% by weight or more, preferably 1% by weight or more, and usually 100% by weight or less, preferably 60% by weight or less, more preferably 50% by weight or less. If the amount of the electron accepting compound is too small, insolubilization may be difficult to occur. By increasing the amount of the electron-accepting compound, the heating time can be insolubilized in a short time. In addition, when using together 2 or more types of electron-accepting compounds, it is made for the total content of these to be contained in the said range.

  The hole transporting compound reacts with the electron-accepting compound during or after the formation of the hole injection layer, whereby the cation radical of the hole transporting compound and An ionic compound may be generated.

<1-1-1-3. Low molecular weight hole transport compound>
As the hole injection material, a low molecular weight hole transporting compound may be used.
The low molecular weight hole transporting compound can be appropriately selected from various compounds that have been conventionally used as a hole injecting / transporting film forming material in an organic electroluminescence device. Among them, those having high solubility in a solvent are preferable.

  Preferable examples of the low molecular weight hole transporting compound include aromatic amine compounds. Of these, aromatic tertiary amine compounds are particularly preferred. Preferable specific examples of the aromatic tertiary amine compound include binaphthyl compounds represented by the following formula (IV).

In the formula (IV), Ar ^{51 to} Ar ⁵⁸ each independently represents an aromatic hydrocarbon group which may have a substituent, or an aromatic heterocyclic group which may have a substituent. Ar ⁵¹ and Ar ⁵² and Ar ⁵⁵ and Ar ⁵⁶ may be bonded to each other to form a ring. Specific examples, preferred examples of Ar ^{51 to} Ar ⁵⁸ , examples of substituents that may be included, and examples of preferred substituents are the same as those exemplified above for Ar ^{1 to} Ar ⁵ , respectively. That is, specific examples of Ar ^{51 to} Ar ⁵⁶ , preferred examples, examples of substituents that may be included, and examples of preferred substituents are the same as those exemplified above for Ar ¹ and Ar ^2. Specific examples, preferred examples of ⁵⁷ and Ar ⁵⁸ , examples of substituents that may be present, and examples of preferred substituents are the same as those exemplified above for Ar ^{3 to} Ar ⁵ .

In formula (IV), u and v each independently represent an integer of 0 or more and 4 or less. However, u + v ≧ 1. Particularly preferred are u = 1 and v = 1.
In formula (IV), Q ¹ and Q ² each independently represents a direct bond or a divalent linking group.
In addition to-(Q ¹ NAr ⁵³ Ar ⁵⁷ (NAr ⁵¹ Ar ⁵² )) and-(Q ² NAr ⁵⁴ Ar ⁵⁸ (NAr ⁵⁵ Ar ⁵⁶ )), the naphthalene ring in formula (IV) has an optional substituent. You may have only 1 type or 2 types or more by arbitrary combinations and ratios. Moreover, these substituents-(Q ¹ NAr ⁵³ Ar ⁵⁷ (NAr ⁵¹ Ar ⁵² ) and-(Q ² NAr ⁵⁴ Ar ⁵⁸ ) (NAr ⁵⁵ Ar ⁵⁶ ) may be substituted at any position of the naphthalene ring. However, among them, binaphthyl compounds substituted on the 4-position and 4′-position of the naphthalene ring in formula (IV) are more preferred.

  The binaphthylene structure in the compound represented by the formula (IV) preferably has a substituent at the 2,2′-position. As the substituent bonded to the 2,2′-position, an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an alkenyl group which may have a substituent, The alkoxycarbonyl group etc. which may have a substituent are mentioned. Note that only one of these substituents may be substituted, or two or more may be substituted in any combination and ratio.

  In the compound represented by the formula (IV), the binaphthylene structure may have an arbitrary substituent other than the 2,2′-position. Examples of the substituent include the groups described above as substituents at the 2,2′-position. The compound represented by the formula (IV) has a substituent at the 2-position and the 2'-position, so that the two naphthalene rings are twisted so that the solubility is improved. In addition, these substituents may be substituted by only one and two or more may be substituted by arbitrary combinations and ratios.

  The molecular weight of the binaphthyl compound represented by the formula (IV) is arbitrary as long as the effects of the present invention are not significantly impaired. From the viewpoint of heat resistance and solubility, it is usually 500 or more, preferably 700 or more, and usually 2000 or less. Preferably it is the range of 1200 or less.

<1-1-2. Solvent>
As a solvent to be contained in the composition for a hole injection layer, any solvent can be used as long as the hole injection layer can be formed. However, it is possible to dissolve at least one of the above-described hole transporting polymer, electron accepting compound, and low molecular weight hole transporting compound, especially two or more, especially all three. Is preferred.

  Specifically, it is preferable that the hole-transporting polymer is usually dissolved at 0.005% by weight or more, particularly 0.5% by weight or more, particularly 1% by weight or more at room temperature and normal pressure. It is preferable to dissolve the compound in an amount of usually 0.001% by weight or more, particularly 0.1% by weight or more, and particularly 0.2% by weight or more. However, a solvent having a high ability to dissolve the hole injection material (solvent ability) is preferable. This is because the concentration of the composition for the hole injection layer can be arbitrarily set to prepare a coating composition having a concentration excellent in the efficiency of the film forming process.

  The solvent used in the composition for the hole injection layer may deactivate the free carrier (cation radical) generated from the hole transporting polymer, the electron accepting compound, the low molecular weight hole transporting compound, and a mixture thereof. It is preferable not to contain a certain deactivated substance or a substance that generates a deactivated substance.

  Since the solvent used for the composition for a hole injection layer is subjected to a stepwise heating process described later, its boiling point is usually 110 ° C. or higher, particularly 200 ° C. or higher, and usually 300 ° C. or lower, especially 270 ° C. or lower. Is preferred. If the boiling point of the organic solvent is too low, the drying speed is high and the film quality may be deteriorated. Further, if the boiling point of the organic solvent is too high, it may be necessary to apply a higher temperature in order to volatilize the solvent in the drying step. Therefore, there is a possibility of affecting other layers and the glass substrate.

  Specific examples of the solvent include ether solvents, ester solvents, aromatic hydrocarbon solvents, amide solvents and the like.

  Examples of ether solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole , Phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole, aromatic ethers such as 2,4-dimethylanisole, and the like.

  Examples of the ester solvent include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate.

  Examples of the aromatic hydrocarbon solvent include toluene, xylene, cyclohexylbenzene, 3-isopropylpropylphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, cyclohexylbenzene, and methylnaphthalene. Can be mentioned.

  Examples of the amide solvent include N, N-dimethylformamide and N, N-dimethylacetamide.

In addition, dimethyl sulfoxide and the like can also be used.
These solvent may use only 1 type and may use 2 or more types by arbitrary combinations and a ratio.

<1-1-3. Other ingredients>
In addition to the above-described hole-transporting polymer, electron-accepting compound, and low-molecular-weight hole-transporting compound, the composition for a hole-injecting layer may further include other components, unless the effects of the present invention are significantly impaired. May be included. Examples of other components include various light emitting materials, electron transporting compounds, binder resins, and coating property improving materials. Other components may be used alone, or two or more may be used in any combination and ratio.

<1-1-4. Composition ratio>
The concentration of the hole injection material in the composition for the hole injection layer is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.01% by weight or more, preferably 0 in terms of film thickness uniformity. .1% by weight or more, more preferably 0.5% by weight or more, and usually 70% by weight or less, preferably 60% by weight or less, more preferably 50% by weight or less. If the concentration is too high, film thickness unevenness may occur, and if it is too low, the formed organic layer may not function.

<1-2. Composition for Hole Transport Layer>
In the method for producing a hole transport layer according to the present invention, the hole transport layer is formed by a wet film formation method.
When forming a hole transport layer by a wet film formation method, a hole transport material and a solvent (a solvent for a hole transport layer) are mixed to prepare a composition for a hole transport layer. The composition can be formed by an appropriate technique on the hole injection layer when the hole injection layer is provided, or on the anode when the hole injection layer is not provided.

In this case, the hole transport layer formed from the composition for hole transport layer may be formed as a layer containing the compound contained in the composition for hole transport layer as it is. It may be a layer containing a compound or the like obtained by reaction of a compound contained in.
The organic electroluminescent device of the present invention may have a configuration in which the hole transport layer is omitted. However, when the hole transport layer is omitted, the organic electroluminescent element of the present invention has a hole injection layer. Moreover, when a hole injection layer is produced with the manufacturing method of the hole injection layer which concerns on this invention, the hole transport layer may be formed by the other method. For example, it may be formed by a vacuum deposition method.

<1-2-1. Hole transport material>
In the present invention, the hole transport material is a material contained in the hole transport layer. Alternatively, the hole transport layer may be formed by the reaction of the material. Furthermore, the hole transport material is not particularly limited as long as it can form a hole transport layer by a wet film-forming method, but in particular, it has a high hole transport property and efficiently transports injected holes. It is preferred that the material be able to. Therefore, it is preferable that the ionization potential is small, the transparency to visible light is high, the hole mobility is large, the stability is high, and impurities that become traps are not easily generated during manufacturing or use.
In many cases, it is in contact with the light-emitting layer, so it is preferable not to quench the light emitted from the light-emitting layer or reduce the efficiency by forming an exciplex with the light-emitting layer.

  Examples of such a hole transporting material include 4,4′-bis [N- (1-naphthyl) -N-phenylamino, in addition to the hole transporting compound used in the above-described hole injection layer. Aromatic diamines containing two or more tertiary amines typified by biphenyl and having two or more condensed aromatic rings substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234681), 4,4 ', 4 "- An aromatic amine compound having a starburst structure such as tris (1-naphthylphenylamino) triphenylamine (J. Lumin., 72-74, 985, 1997), a fragrance comprising a tetramer of triphenylamine Group amine compounds (Chem. Commun., 2175, 1996), spirolation of 2,2 ′, 7,7′-tetrakis- (diphenylamino) -9,9′-spirobifluorene, etc. Things (Synth.Metals, 91 vol, 209 pp., 1997), 4,4'-N, such as a carbazole derivative such as N'- dicarbazole biphenyl.

  Furthermore, it is also possible to use a compound that is polymerized by heating, irradiation with electromagnetic waves such as light or magnetism, or a polymer in which any plural compounds are polymerized in advance after forming a film by a film forming method described later. Examples of the compound that is polymerized by heating, irradiation with electromagnetic waves such as light and magnetism include triarylamine derivatives and fluorene derivatives having a crosslinking group, and the crosslinking group is an unsaturated double group such as a cyclic ether group or a vinyl group. And a group having a bond. Among them, a heat-crosslinkable compound that is polymerized by heat is preferable in order to improve the homogeneity of the film by the stepwise heating process and the second heating.

  Examples of such a polymer include polyvinyl carbazole, polyvinyl triphenylamine (Japanese Patent Laid-Open No. 7-53953), and polyarylene ether sulfone (Polym. Adv. Tech., Vol. 7, page 33) containing tetraphenylbenzidine. 1996). One of these may be used alone, or two or more may be used in any combination and ratio.

<1-2-2. Solvent>
As a solvent to be contained in the composition for a hole transport layer, any solvent can be used as long as the hole transport layer can be formed. However, the ability to dissolve the above hole transport material (solvent ability) High solvents are preferred. This is because the concentration of the composition for the hole transport layer can be arbitrarily set to prepare a coating composition having a concentration excellent in the efficiency of the film forming process.
However, those that do not attack the lower layer, such as dissolving the lower layer to which the hole transport layer is applied, are preferred.

  The solvent used in the composition for the hole transport layer may not include a deactivating substance that may deactivate a free carrier (cation radical) generated from a hole transporting compound or the like or a substance that generates a deactivating substance. preferable.

  Since the solvent used in the composition for a hole transport layer is subjected to a stepwise heating process described later, its boiling point is usually 110 ° C. or higher, particularly 200 ° C. or higher, and usually 300 ° C. or lower, especially 270 ° C. or lower. Is preferred. If the boiling point of the organic solvent is too low, the drying speed is high and the film quality may be deteriorated. Further, if the boiling point of the organic solvent is too high, it may be necessary to apply a higher temperature in order to volatilize the solvent in the drying step. Therefore, there is a possibility of affecting other layers and the glass substrate.

  Specific examples of the solvent include ether solvents, ester solvents, aromatic hydrocarbon solvents, amide solvents and the like.

  Examples of ether solvents include aliphatic ethers such as ethylene glycol dimethyl ether, ethylene glycol diethyl ether, and propylene glycol-1-monomethyl ether acetate (PGMEA); 1,2-dimethoxybenzene, 1,3-dimethoxybenzene, anisole , Aromatic ethers such as phenetole, 2-methoxytoluene, 3-methoxytoluene, 4-methoxytoluene, 2,3-dimethylanisole and 2,4-dimethylanisole.

  Examples of the ester solvent include aromatic esters such as phenyl acetate, phenyl propionate, methyl benzoate, ethyl benzoate, propyl benzoate, and n-butyl benzoate.

  Examples of the aromatic hydrocarbon solvent include toluene, xylene, cyclohexylbenzene, 3-isopropylpropylphenyl, 1,2,3,4-tetramethylbenzene, 1,4-diisopropylbenzene, cyclohexylbenzene, and methylnaphthalene. Can be mentioned.

Examples of the amide solvent include N, N-dimethylformamide and N, N-dimethylacetamide.
In addition, dimethyl sulfoxide and the like can also be used.
These solvent may use only 1 type and may use 2 or more types by arbitrary combinations and a ratio.

<1-2-3. Other ingredients>
The composition for a hole transport layer may further contain other components in addition to the above-described hole transport compound unless the effects of the present invention are significantly impaired. Examples of other components include various light emitting materials, electron transporting compounds, binder resins, coatability improving agents, and the like. In addition, only 1 type may be used for another component, and 2 or more types may be used together by arbitrary combinations and a ratio.

<1-2-4. Composition ratio>
The concentration of the hole transport material in the composition for a hole transport layer is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.01% by weight or more, preferably 0 in terms of film thickness uniformity. .1% by weight or more, more preferably 0.5% by weight or more, and usually 70% by weight or less, preferably 60% by weight or less, more preferably 50% by weight or less. If the concentration is too high, film thickness unevenness may occur, and if it is too low, the formed organic layer may not function.

[2. Method for forming hole injection layer and / or hole transport layer]
In the method for producing an organic electroluminescent element of the present invention, at least one of a hole injection layer and a hole transport layer is formed by a wet film formation method (film formation step), and the specific film described later is formed on the formed film. It is formed by drying by the drying method (drying step).
Hereinafter, each of the film forming process and the drying process will be described.

<2-1. Film formation process>
The film forming step in the present invention is performed by applying the above-described hole injection layer composition or hole transport layer composition by a wet film forming method. The wet film formation method is superior to the vapor deposition method in that it provides a homogeneous and defect-free film, and because the formation time is short, it has the advantage of being hardly affected by particles. It is a membrane method.

(Application method)
If the film-forming method in a film-forming process is a wet film-forming method, there will be no restriction | limiting unless the effect of this invention is impaired remarkably. For example, spin coating method, dip coating method, die coating method, bar coating method, blade coating method, roll coating method, spray coating method, capillary coating method, ink jet method, screen printing method, gravure printing method, flexographic printing method, offset printing Etc.
Among these, die coating, roll coating, spray coating, ink jet, flexographic printing, and the like are preferable in terms of ease of patterning.

(Deposition temperature)
The film formation temperature in the film formation step is not limited as long as the effects of the present invention are not significantly impaired. However, in order to prevent film loss due to the formation of crystals in the coating composition, it is preferably 10 ° C. or higher, and 13 ° C. or higher. More preferably, 16 ° C. or higher is further preferable, 50 ° C. or lower is preferable, 40 ° C. or lower is more preferable, and 30 ° C. or lower is further preferable.

(Deposition humidity)
The relative humidity in the film forming step is not limited as long as the effect of the present invention is not significantly impaired, but is usually 0.01 ppm or more, preferably 0.05 ppm or more, more preferably 0.1 ppm or more, usually 80% or less, preferably 60 % Or less, more preferably 15% or less, still more preferably 1% or less, and particularly preferably 100 ppm or less. If the relative humidity is too small, it becomes difficult to control film forming conditions in the wet film forming method, and a stable environment cannot be maintained. On the other hand, if it is too large, moisture adsorption on the organic layer may be affected.

(Oxygen concentration)
The volume concentration of oxygen in the film forming step is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 0.01 ppm or more, more preferably 0.05 ppm or more, and preferably 50% or less, more preferably 25. % Or less, more preferably 1% or less, particularly preferably 100 ppm or less, particularly preferably 10 ppm or less. An environment where the oxygen concentration is too low is difficult to control and cannot maintain a stable environment. If the oxygen concentration is too high, oxygen diffuses inside the organic layer, which may adversely affect device characteristics.

(Number of particles)
The number of fine particles (that is, the number of particles) in the film forming environment is not limited as long as the effect of the present invention is not significantly impaired. From the viewpoint of reducing dark spots, particles having a particle size of 0.5 μm or more are usually per 1 m ^3. It is 10,000 or less, preferably 5000 or less. Particularly preferably, the number of particles having a particle diameter of 0.3 μm or more is 5000 or less per 1 m ³ . Although there is no restriction | limiting in a lower limit, from a viewpoint of industrial practicality, it can be considered that normally 100 particles with a particle size of 0.3 μm or more exist per 1 m ³ . If the number of particles is too large, dark spots may occur, and environmental control tends to become more difficult as the number falls below the above range.
The number of fine particles is detected by a light scattering method, and can be detected by, for example, a handheld particle counter KR (manufactured by Lion Co., Ltd.).

(Film thickness)
The film thickness of the organic layer formed in the film forming step is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 10 nm or more, more preferably 15 nm or more, further preferably 20 nm or more, and preferably 30 μm or less. More preferably, it is 20 micrometers or less, More preferably, it is 15 micrometers or less. This is because high film thickness accuracy can be obtained within this range.
If it is less than 10 nm, it may be mixed with the underlying layer and may not function as a layer. If it exceeds 30 μm, the voltage applied during light emission increases, leading to a reduction in efficiency.
The film thickness accuracy is defined as the ratio between the maximum value and the minimum value of the film thickness of the light emitting portion (the organic layer portion sandwiched between the anode and the cathode). The film thickness accuracy is measured with a contact film thickness meter or an interference film thickness meter.

(Processing after application)
There is no particular limitation on the treatment after coating, but if it is left in the atmosphere for a long time after coating, dark spots or bright spots may occur due to particles or moisture adsorption. Therefore, it is preferable to move to the heating process immediately after the film forming process. Usually, it is within 30 minutes, preferably within 10 minutes, more preferably within 1 minute.

<2-2. Drying process>
The drying process is a process of removing the solvent contained in the layer formed in the film forming process from the layer. In the method for producing an organic electroluminescent element of the present invention, the drying step includes a first heating step of heating at a temperature equal to or higher than the boiling point of the solvent, a first cooling step of cooling, and a second heating step of heating. It goes through in order. Moreover, as long as the effect of this invention is not impaired remarkably, you may pass through another process. Hereinafter, these steps will be described in detail.

<2-2-1. First heating step>
In the first heating step, the solvent contained in the hole injection layer and / or hole transport layer formed in the film formation step (that is, the solvent and / or positive solvent contained in the composition for hole injection layer). It is a step of volatilizing and removing the solvent by heating at a temperature equal to or higher than the boiling point of the solvent contained in the composition for the hole transport layer. Hereinafter, although a 1st heating process is demonstrated, if it heats at the temperature more than the boiling point of the said solvent, it will not be limited to the following.

  The heating means that can be used in the first heating step is not limited as long as the effects of the present invention are not significantly impaired. Specific examples include a method using a clean oven, a hot plate, infrared rays, a halogen heater, microwave irradiation, and the like. Among them, a clean oven and a hot plate are preferable in order to uniformly apply heat to the entire film. Moreover, you may carry out combining 2 or more types among these methods.

  The heating direction in the first heating step is not limited as long as the effects of the present invention are not significantly impaired. Examples of the heating direction include, for example, mounting a base material on a hot plate and heating the liquid film through the hot plate, so that the liquid film is removed from the lower surface of the substrate (the surface on which the organic layer is not applied). A method of heating, a method of heating a liquid film from all directions, front, back, left, and right by putting a substrate into a clean oven can be mentioned.

(Heating temperature)
The heating temperature in the first heating step is not limited as long as the effects of the present invention are not significantly impaired, but [1. It is preferable to heat at a temperature equal to or higher than the boiling point of the solvent described in [Composition containing hole injection material and / or hole transport material and solvent]. Moreover, when heating the mixed solvent in which two or more types of the solvent shown above are contained, it is preferable to heat at the temperature more than the boiling point of at least one type of solvent.

Specifically, in consideration of an increase in the boiling point of the solvent, the film is preferably formed in the film formation step when heated at 120 ° C. or higher, more preferably 200 ° C. or higher, and preferably 310 ° C. or lower, more preferably 270 ° C. or lower. The solvent contained in the formed layer can be sufficiently volatilized. If the temperature is too high above this range, the components of other layers may diffuse to another adjacent layer. Also, if the temperature is too lower than this range, the solvent may remain in the layer.
The heating temperature here refers to the temperature of the substrate on which the layer subjected to the first heating step is formed.

(Temperature increase rate)
The rate of temperature increase in the first heating step is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 10 ° C./second or more, more preferably 20 ° C./second or more, further preferably 30 ° C./second or more. Further, it is preferably 100 ° C./second or less, more preferably 90 ° C./second or less. This makes it possible to volatilize the solvent without significantly disturbing the film surface. If the rate of temperature increase is too small, the heating time becomes longer, which may adversely affect other layers, and if the rate of temperature increase is too large, the load on the substrate may be great and cause damage.

(Heating time)
The heating time of the first heating step is not limited as long as the heating temperature is equal to or higher than the boiling point, and the layer formed in the film forming step is not sufficiently insolubilized, but is preferably 10 seconds or longer, more preferably 30 seconds. More preferably, it is 1 minute or more, preferably 30 minutes or less, more preferably 10 minutes or less, and further preferably 5 minutes or less. If the heating time is too long, the components of the other layers tend to diffuse, and if it is too short, the layers formed in the film forming process tend to be inhomogeneous.

(Degree of vacuum)
The first heating step can be performed under atmospheric pressure. Moreover, it can also carry out under reduced pressure, unless the effect of this invention is impaired remarkably. When the pressure is reduced, the degree of vacuum is preferably 1 × 10 ⁻² Pa or less, more preferably 1 × 10 ⁻³ Pa or less, still more preferably 5 × 10 ⁻⁴ Pa or less, and the lower limit is not limited. Usually, it is 1 × 10 ⁻⁵ Pa or more. If the degree of vacuum is too high, it takes time to increase the degree of vacuum, and environmental control during that time tends to be difficult, and if it is too low, the solvent tends to remain in the layer.

(Film thickness after the first heating step)
The thickness of the layer subjected to the first heating step is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 10 nm or more, more preferably 15 nm or more, further preferably 20 nm or more, and preferably 300 nm or less. More preferably, it is 200 nm or less, More preferably, it is 150 nm or less. If the film thickness is too small, the layer may not function. In addition, if the film thickness is too large, the influence of element characteristics may increase due to film thickness unevenness.

(Film thickness accuracy after the first heating step)
The film thickness accuracy of the layer subjected to the first heating step is preferably 500% or less, more preferably 300% or less, further preferably 200% or less, preferably 2% or more, more preferably 5% or more, Preferably it is 8% or more. If the film thickness accuracy is too large, device characteristics such as light emission unevenness tend to be unstable, and if it is too small, the layer may not function, and the film quality tends to be non-homogeneous. The definition of the film thickness accuracy is as described above.

<2-2-2. First cooling step>
In the first cooling step, the layer heated in the first heating step is cooled. Thereby, the internal distortion of the layer by heating can be relieved.
Hereinafter, although a 1st cooling process is demonstrated, unless the effect of this invention is impaired remarkably, it is not limited to this.

  The cooling means that can be used in the first cooling step is not limited as long as the effects of the present invention are not significantly impaired. Specific examples include natural cooling, air cooling, and refrigeration.

(Cooling temperature)
The cooling temperature in the first cooling step is preferably 150 ° C. or lower, more preferably 120 ° C. or lower, further preferably 100 ° C. or lower, and particularly preferably 80 ° C. or lower. If the cooling temperature is too high, distortion may remain at the interface between the layers, which may cause peeling.
The cooling temperature here refers to the temperature of the substrate on which the layer subjected to the first cooling step is formed.

In order to reduce the internal strain of the film, the temperature difference between the first heating step and the first cooling step is usually 80 ° C. or higher, preferably 100 ° C. or higher, more preferably 150 ° C. or higher, Preferably it is 300 degrees C or less, More preferably, it is 250 degrees C or less. If the temperature difference is small, relaxation becomes insufficient, and if the temperature difference is too large, defects may occur.
Note that the temperature difference at this time is the temperature of the substrate on which the layer immediately after the first heating step is formed and the layer when the temperature is cooled until the temperature becomes constant by the first cooling step. The difference from the temperature of the substrate on which is formed.

(Cooling rate)
The cooling rate in the first cooling step is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 0.1 ° C./min or more, more preferably 0.5 ° C./min or more, and still more preferably 0.8. 8 ° C./min or more, particularly preferably 1 ° C./min or more, preferably 50 ° C./min or less, more preferably 30 ° C./min or less, further preferably 20 ° C./min or less, particularly preferably 10 ° C./min. It is as follows. In this way, by gradually cooling the thin film, a smooth film surface tends to be maintained. If the cooling rate is too low, the strain cannot be alleviated and defects are likely to occur in the film. If the cooling rate is too high, the linear expansion between adjacent layers may be different, which may cause delamination of the laminated interface.

(time)
The time after the start of cooling in the first cooling step is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 1 minute or more, more preferably 5 minutes or more, further preferably 10 minutes or more, , Preferably 1 hour or less, more preferably 45 minutes or less, and even more preferably 30 minutes or less. If it is too short, the glass substrate may be damaged by rapid cooling. If it is too long, particles in the atmosphere may adhere to the substrate and cause dark spots.

(Film thickness after the first cooling step)
The film thickness of the layer subjected to the first cooling step is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 10 nm or more, more preferably 15 nm or more, further preferably 20 nm or more, and preferably 300 nm or less. More preferably, it is 200 nm or less, More preferably, it is 150 nm or less. If the film thickness is too small, the layer may not function. In addition, if the film thickness is too large, the influence of element characteristics may increase due to film thickness unevenness.

(Film thickness accuracy after the first cooling step)
The film thickness accuracy of the layer subjected to the first cooling step is preferably 500% or less, more preferably 300% or less, further preferably 200% or less, preferably 2% or more, more preferably 5% or more, Preferably it is 8% or more. If the film thickness accuracy is too large, device characteristics such as light emission unevenness tend to be unstable, and if it is too small, the layer may not function, and the film quality tends to be non-homogeneous. The definition of the film thickness accuracy is as described above.

<2-2-3. Second heating step>
After the first cooling step, a second heating step for heating the cooled layer is performed. Hereinafter, although a 2nd heating process is demonstrated, unless the effect of this invention is impaired remarkably, it is not limited to the following.

  The heating means that can be used in the second heating step is not limited as long as the effects of the present invention are not significantly impaired. Specific examples include a method using a clean oven, a hot plate, infrared rays, a halogen heater, microwave irradiation, and the like. Among these, a clean oven and a hot plate are preferable in order to uniformly apply heat to the entire film. Moreover, you may carry out combining 2 or more types of these methods.

  The heating direction in the second heating step is not limited as long as the effects of the present invention are not significantly impaired. Examples of heating directions include, for example, mounting a base material on a hot plate and heating the thin film through the hot plate to heat the thin film from the lower surface of the substrate (the surface on which the organic layer is not applied). And a method of heating the thin film from all directions, front, rear, left, and right by putting the substrate into a clean oven.

(Heating temperature)
The heating temperature in the second heating step is not particularly limited as long as the effects of the present invention are not significantly impaired. In order to remove a very small amount of residual solvent from the film stabilized by the cooling step, [1. It is preferable to heat at a temperature equal to or higher than the boiling point of the solvent shown in [Composition containing hole injection material and / or hole transport material and solvent]. Moreover, when heating the mixed solvent in which 2 or more types of solvents shown above are contained, it is preferable that at least 1 type is heated at the temperature more than the boiling point of the solvent.

Specifically, it is usually 110 ° C. or higher, preferably 200 ° C. or higher, and usually 300 ° C. or lower, preferably 270 ° C. or lower. If the temperature is higher than this range, components may diffuse to other layers. Further, if the temperature is too lower than this range, there is a possibility that a trace amount of residual solvent cannot be removed.
Note that the heating temperature here refers to the temperature of the layer subjected to the second heating step.

(Temperature increase rate)
The temperature increase rate in the second heating step is preferably 3 ° C./second or more, more preferably 4 ° C./second or more, and still more preferably 5 in order to obtain film homogeneity without applying a load to the lamination interface. C./second or more, preferably 150.degree. C./second or less, more preferably 120.degree. C./second or less, still more preferably 100.degree. C./second.
If the heating rate is too low, homogeneity cannot be obtained, and if the heating rate is too high, the load on the substrate is great and may cause damage.

(Heating time)
The heating measure in the second heating step is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 30 minutes or more, more preferably 1 hour or more, further preferably 3 hours or more, and preferably 9 hours or less. More preferably, it is 7 hours or less, More preferably, it is 5 hours or less. Thereby, the thin film can be sufficiently insolubilized. If the heating time is too long, the components of the other layers tend to diffuse, and if it is too short, the homogeneity of the film tends to decrease.

(Degree of vacuum)
The second heating step can be performed under atmospheric pressure. Moreover, it can also carry out under reduced pressure, unless the effect of this invention is impaired remarkably. When the pressure is reduced, the degree of vacuum is preferably 1 × 10 ⁻² Pa or less, more preferably 1 × 10 ⁻³ Pa or less, still more preferably 5 × 10 ⁻⁴ Pa or less, and the lower limit is not limited. Usually, it is 1 × 10 ⁻⁵ Pa or more. If the degree of vacuum is too high, it takes time to increase the degree of vacuum, and environmental control during that time tends to be difficult, and if it is too low, the solvent tends to remain in the layer.

(Film thickness after the second heating step)
The film thickness of the layer subjected to the second heating step is not limited as long as the effect of the present invention is not significantly impaired, but is preferably 10 nm or more, more preferably 15 nm or more, further preferably 20 nm or more, and preferably 300 nm or less. More preferably, it is 200 nm or less, More preferably, it is 150 nm or less. If the film thickness is too small, the layer may not function. In addition, if the film thickness is too large, the influence of element characteristics may increase due to film thickness unevenness.

(Film thickness accuracy after the second heating step)
The film thickness accuracy of the layer subjected to the second heating step is preferably 500% or less, more preferably 300% or less, further preferably 200% or less, preferably 2% or more, more preferably 5% or more, Preferably it is 8% or more. If the film thickness accuracy is too large, device characteristics such as light emission unevenness tend to be unstable, and if it is too small, the layer tends not to function, and the film quality tends to become inhomogeneous. The definition of the film thickness accuracy is as described above.

<2-2-4. Other processes>
The drying step may have other steps in addition to the steps described above. For example, a second cooling step may be performed in order to relieve internal strain of the film due to the second heating step. The second cooling step can be performed by the same method as the first cooling step.

  In addition, if the drying process is performed in this order in the first heating process, the first cooling process, and the second heating process, a heating process or a cooling process may be performed unless the effects of the present invention are significantly impaired. You may do it.

[3. Organic electroluminescent device]
Hereinafter, the structure of the organic electroluminescent element according to the present invention will be described. The organic electroluminescent element according to the present invention has a hole injection layer and / or a hole transport layer and a light emitting layer between the anode and the cathode.
In addition, at least one of the hole injection layer and the hole transport layer may be an organic layer manufactured through the film formation process and the drying process described above, and the other layers are formed by other methods such as vapor deposition. It may be. In addition, although layers other than a positive hole injection layer and a positive hole transport layer are also preferably formed with the organic material, it is not limited to this, There is no restriction | limiting, unless the effect of this invention is impaired remarkably.

  Examples of the organic layer constituting the organic electroluminescent element include layers such as a hole injection layer, a hole transport layer, a light emitting layer, a hole blocking layer, an electron transport layer, an electron injection layer, and an electron blocking layer. These layers can also be formed by other methods such as a wet film forming method and a vapor deposition method. However, at least one of the hole injection layer and the hole transport layer is manufactured by the method for manufacturing a hole injection layer according to the present invention and / or the method for manufacturing a hole transport layer according to the present invention. Note that if the light emitting layer is a layer made of a low molecular weight compound compared to the wet film forming method, the low molecular weight compound reduces film unevenness (particularly the film thickness), and thus suppresses deterioration such as current concentration during light emission. A long-life organic electroluminescent device is preferably obtained.

  The organic electroluminescent element of the present invention usually comprises a substrate, an anode is formed on the substrate, each of the above-mentioned layers is laminated thereon, and a laminated structure in which a cathode is formed on the layer. Is. Alternatively, the cathode may be formed on the substrate, the layers may be stacked on the substrate in the reverse order to the above configuration, and the anode may be formed on the outer layer. Hereinafter, the former case will be used as an example to describe the order of stacking from the substrate side.

  FIG. 1 is a cross-sectional view schematically showing an example of the structure of the organic electroluminescent element of the present invention. An organic electroluminescent device 10 shown in FIG. 1 includes an anode 2, a hole injection layer 3, a hole transport layer 4, a light emitting layer 5, a hole blocking layer 6, an electron transport layer 7, and an electron injection layer on a substrate 1. 8 and the cathode 9 are laminated in this order.

<3-1. Substrate>
The substrate 1 serves as a support for the organic electroluminescent element 10, and a quartz or glass plate, a metal plate or a metal foil, a plastic film, a sheet, or the like is used. In particular, it is preferable to use a transparent substrate made of a general-purpose material such as a glass plate, a transparent synthetic resin plate such as polyester, polymethacrylate, polycarbonate, or polysulfone.

  Examples of the material of the substrate 1 include various types of shot glass such as BK7, SF11, LaSFN9, BaK1, and F2, synthetic phased silica glass, optical crown glass, low expansion borosilicate glass, sapphire glass, soda glass, and alkali-free glass. Glass, TFT-formed glass, and polymer materials include acrylic resins such as polymethylmethacrylate and cross-linked acrylate, aromatic polycarbonate resins such as bisphenol A polycarbonate, polyester resins such as polyethylene terephthalate, and polycycloolefins. Examples thereof include crystalline polyolefin resins, epoxy resins, styrene resins such as polystyrene, polysulfone resins such as polyethersulfone, and synthetic resins such as polyetherimide resin. Moreover, 2 or more types of laminated bodies may be sufficient among these. Depending on the purpose and application, an optical film such as an antireflection film, a circularly polarizing film, or a retardation film may be formed on or bonded to these substrates.

  However, it is preferable to pay attention to gas barrier properties when using a synthetic resin substrate. This is because if the gas barrier property of the substrate 1 is too small, the organic electroluminescent element 10 may be deteriorated by the outside air that has passed through the substrate 1. For this reason, a method of providing a gas barrier property by providing a dense silicon oxide film or the like on at least one surface of the synthetic resin substrate is also a preferable method.

<3-2. Anode>
An anode 2 is provided on the substrate 1. The anode 2 injects holes into the hole injection layer 3 (or the hole transport layer 4 in the case where the hole injection layer 3 is not provided).

The material of the anode 2 is usually a metal such as aluminum, gold, silver, nickel, palladium, or platinum; a metal oxide such as an oxide of indium and / or tin; a metal halide such as copper iodide; a carbon black Or a conductive polymer such as poly (3-methylthiophene), polypyrrole, or polyaniline.
In addition, only 1 type may be used for the material of the anode 2, and 2 or more types may be used together by arbitrary combinations and a ratio.

Although there is no restriction | limiting in the formation method of the anode 2, Usually, it carries out by sputtering method, a vapor deposition method, etc. In addition, when forming the anode 2 using fine metal particles such as silver, fine particles such as copper iodide, carbon black, conductive metal oxide fine particles, and conductive polymer fine powder, an appropriate binder resin solution is used. The anode 2 can also be formed by dispersing them and applying them onto the substrate 1. Furthermore, in the case of a conductive polymer, a thin film can be directly formed on the substrate 1 by electrolytic polymerization, or the anode 2 can be formed by applying a conductive polymer on the substrate 1 (Appl. Phys. Lett. 60, 2711, 1992).
In addition, the anode 2 is usually a single layer structure, but may be a laminated structure made of a plurality of materials if desired.

  The thickness of the anode 2 varies depending on the required transparency. When transparency is required, the visible light transmittance is usually 60% or more, preferably 80% or more. In this case, the thickness of the anode 2 is usually 5 nm or more, preferably 10 nm or more. Also, it is usually 1000 nm or less, preferably 500 nm or less. On the other hand, when the anode 2 may be opaque, the thickness of the anode 2 is arbitrary, and the anode 2 may be the same as the substrate 1. Further, it is possible to laminate different conductive materials on the anode 2.

Further, for the purpose of removing impurities adhering to the anode 2 and adjusting the ionization potential to improve the hole injection property, the surface of the anode 2 is subjected to ultraviolet (UV) / ozone treatment, oxygen plasma, argon plasma. It is preferable to process.
Furthermore, a known anode buffer layer is inserted between the hole injection layer 3 and the anode 2 for the purpose of further improving the efficiency of hole injection and improving the adhesion of the entire organic layer to the anode 2. May be.

<3-3. Hole injection layer>
The hole injection layer 3 is provided on the anode 2. The hole injection layer 3 is a layer that transports holes from the anode 2 to the hole transport layer 4 (the light emitting layer 5 when the hole transport layer 4 is not provided).
The materials of the hole injection layer 3, preferred materials, usage ratios, etc. are described in <1-1. As described for composition for hole injection layer>. Moreover, although the manufacturing method of the hole injection layer 3 is preferably manufactured through the film forming step and the drying step described above, if different, the hole transport layer 4 is placed on the hole injection layer 3. The film is manufactured through the film forming process and the drying process described above.
A configuration in which the hole injection layer 3 is omitted is possible, but in such a case, the hole transport layer 4 is provided.

<3-4. Hole transport layer>
The hole transport layer 4 is provided on the hole injection layer 3 and on the anode 2 in the case where the hole injection layer 3 is not provided. The hole transport layer 4 is a layer that transports holes from the anode 2 to the light emitting layer 5 (or from the anode 2 to the light emitting layer 5 when the hole injection layer 3 is not provided) via the hole injection layer 3.
The materials of the hole transport layer 4, preferred materials, usage ratios, etc. are <1-2. As described for composition for hole transport layer>. Moreover, although it is preferable that the manufacturing method of the positive hole transport layer 4 is manufactured through the film-forming process and drying process mentioned above, the positive hole transport layer 4 was manufactured through the film-forming process and drying process mentioned above. In some cases, it can be produced by other methods.
A configuration in which the hole transport layer 4 is omitted is possible, but in such a case, the hole injection layer 3 is provided.

  That is, the organic electroluminescent element of the present invention includes a hole injection layer 3 manufactured through the film forming process and a drying process, and a hole transport layer 4 manufactured through the film forming process and the drying process. Among them, at least one of them is included. However, it is preferable that both the hole injection layer 3 and the hole transport layer 4 are manufactured through the film forming process and the drying process described above. This is because a light-emitting layer can be formed on a smoother film surface, and thus a long-life organic electroluminescent element can be obtained.

<3-5. Light emitting layer>
The light emitting layer 5 is provided on the hole transport layer 4, and on the hole injection layer 3 in the case where the hole transport layer 4 is not provided. The light emitting layer 5 is excited by recombination of holes injected from the anode 2 through the hole injection layer 3 and the like and electrons injected from the cathode 9 through the electron injection layer 8 and the like between the electrodes to which an electric field is applied. Thus, it is a layer that becomes a main light source.
The organic electroluminescent element 10 of the present invention preferably has a light emitting layer formed by a wet film forming method as the light emitting layer 5, and a light emitting layer containing a low molecular compound formed by a wet film forming method. It is more preferable to have a light emitting layer made of only a low molecular weight compound formed by a wet film formation method.

<3-5-1. Light emitting layer material>
The light emitting layer 5 contains at least a material having a light emitting property (light emitting material) as a constituent material, and preferably a compound having a hole transporting property (hole transporting compound) or an electron transporting material. Contains a compound having properties (electron transporting compound). There is no particular limitation on the light-emitting substance, and a substance that emits light at a desired emission wavelength and has high emission efficiency may be used. Moreover, it is preferable to contain two or more charge transport compounds. Furthermore, the light emitting layer 5 may contain other components as long as the effects of the present invention are not significantly impaired.

  In addition, when forming the light emitting layer 5 by the specific organic layer formation method, it is preferable to use a low molecular compound in any case. In addition, a low molecular compound means the compound whose weight average molecular weight is 6000 or less normally, Preferably it is 5000 or less, More preferably, it is 1500 or less.

<3-5-1-1. Luminescent material>
Any known material can be applied as the light emitting material. For example, a fluorescent material or a phosphorescent material may be used, but a phosphorescent material is preferable from the viewpoint of internal quantum efficiency.
In order to improve the solubility in a solvent, it is preferable to reduce the symmetry and rigidity of the molecules of the luminescent material or introduce a lipophilic substituent such as an alkyl group.

  Hereinafter, although the example of a fluorescent dye is mentioned among light emitting materials, a fluorescent dye is not limited to the following illustrations.

  Examples of fluorescent dyes that give blue light emission (blue fluorescent dyes) include perylene, pyrene, anthracene, coumarin, chrysene, naphthalene, p-bis (2-phenylethenyl) benzene, and derivatives thereof.

  Examples of fluorescent dyes that give green light emission (green fluorescent dyes) include quinacridone derivatives and coumarin derivatives.

  Examples of fluorescent dyes that give yellow light (yellow fluorescent dyes) include rubrene and perimidone derivatives.

  Examples of fluorescent dyes that give red luminescence (red fluorescent dyes) include DCM (4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran) compounds, benzopyran derivatives, rhodamine derivatives, benzoates. Examples thereof include thioxanthene derivatives and azabenzothioxanthene.

  Next, phosphorescent materials among the light emitting materials will be described. Examples of the phosphorescent material include an organometallic complex containing a metal selected from Groups 7 to 11 of the periodic table.

  Preferred examples of the metal selected from Groups 7 to 11 of the periodic table contained in the phosphorescent organometallic complex include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, and gold. . Preferred examples of these organometallic complexes include compounds represented by the following formula (V) or formula (VI).

  In formula (V), M represents a metal, and q represents the valence of the metal. L and L ′ each represents a bidentate ligand. j represents a number of 0, 1 or 2.

In the above formula (VI), M ⁷ represents a metal, and T represents a carbon atom or a nitrogen atom. R ^{92 to} R ⁹⁵ each independently represents a substituent. However, when T is a nitrogen atom, R ⁹⁴ and R ⁹⁵ are absent.

Hereinafter, the compound represented by the formula (V) will be described first.
In formula (V), M represents an arbitrary metal, and specific examples of preferable ones include the metals described above as metals selected from Groups 7 to 11 of the periodic table.

In the formula (V), the bidentate ligand L represents a ligand having the following partial structure.

In the partial structure of L, ring A1 ″ represents an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent.

  Examples of the aromatic hydrocarbon group constituting the ring A1 ″ include a 5- or 6-membered monocyclic ring or a 2-5 condensed ring. Specific examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, and a phenanthrene. And a monovalent group derived from a ring, a perylene ring, a tetracene ring, a pyrene ring, a benzpyrene ring, a chrysene ring, a triphenylene ring, an acenaphthene ring, a fluoranthene ring, and a fluorene ring.

  Examples of the aromatic heterocyclic group constituting the ring A1 ″ include a 5- or 6-membered monocyclic ring or a 2-4 condensed ring. Specific examples thereof include a furan ring, a benzofuran ring, a thiophene ring, and a benzoic ring. Thiophene ring, pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, thienothiophene ring, furopyrrole ring, furofuran ring, thienofuran ring , Benzoisoxazole ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, cinnoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring , Perimidine ring, key Gelsolin ring, quinazolinone ring, and a monovalent group derived from azulene ring.

In the partial structure of L, ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.
Examples of the nitrogen-containing aromatic heterocyclic group constituting the ring A2 include a 5- or 6-membered monocyclic ring or a 2-4 condensed ring. Specific examples thereof include pyrrole ring, pyrazole ring, imidazole ring, oxadiazole ring, indole ring, carbazole ring, pyrroloimidazole ring, pyrrolopyrazole ring, pyrrolopyrrole ring, thienopyrrole ring, furopyrrole ring, thienofuran ring, benzoisoxazole Ring, benzoisothiazole ring, benzimidazole ring, pyridine ring, pyrazine ring, pyridazine ring, pyrimidine ring, triazine ring, quinoline ring, isoquinoline ring, quinoxaline ring, phenanthridine ring, benzimidazole ring, perimidine ring, quinazoline ring, And monovalent group derived from a quinazolinone ring.

Examples of the substituent that each ring A1 ″ or ring A2 may have include: a halogen atom such as a fluorine atom; an alkyl group such as a methyl group and an ethyl group; an alkenyl group such as a vinyl group; a methoxycarbonyl group and an ethoxy group Alkoxycarbonyl groups such as carbonyl groups; alkoxy groups such as methoxy groups and ethoxy groups; aryloxy groups such as phenoxy groups and benzyloxy groups; dialkylamino groups such as dimethylamino groups and diethylamino groups; diarylamino groups such as diphenylamino groups Carbazolyl group; acyl group such as acetyl group; haloalkyl group such as trifluoromethyl group; cyano group; aromatic hydrocarbon group such as phenyl group, naphthyl group, phenanthyl group and the like.
In addition, as for the said substituent, only 1 may be substituted and 2 or more may be substituted by arbitrary combinations and ratios.

In the formula (V), the bidentate ligand L ′ represents a ligand having at least one of the following partial structures. In the following formulae, “Ph” represents a phenyl group.

Among these, as L ′, the following ligands are preferable from the viewpoint of the stability of the complex.

  More preferable examples of the compound represented by the above formula (V) include compounds represented by at least one of the following formulas (Va), (Vb) and (Vc).

In the formula (Va), M ⁴ represents the same metal as M, w represents the valence of the metal, and ring A1 ″ represents an aromatic hydrocarbon group which may have a substituent. Ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

In the above formula (Vb), M ⁵ represents the same metal as M, w represents the valence of the metal, and ring A1 ″ represents an aromatic hydrocarbon group which may have a substituent or Represents an aromatic heterocyclic group, and ring A2 represents a nitrogen-containing aromatic heterocyclic group which may have a substituent.

In the above formula (Vc), M ⁶ represents the same metal as M, w represents the valence of the metal, j represents 0, 1 or 2, ring A1 ″ and ring A1 ′ are Each independently represents an optionally substituted aromatic hydrocarbon group or aromatic heterocyclic group, and ring A2 and ring A2 ′ are each independently a nitrogen-containing optionally substituted group. Represents an aromatic heterocyclic group.

  In the above formulas (Va), (Vb) and (Vc), preferred examples of the ring A1 ″ and the ring A1 ′ include a phenyl group, a biphenyl group, a naphthyl group, an anthryl group, a thienyl group, a furyl group, a benzothienyl group, A benzofuryl group, a pyridyl group, a quinolyl group, an isoquinolyl group, a carbazolyl group, and the like can be given.

  In the above formulas (Va), (Vb) and (Vc), preferred examples of ring A2 and ring A2 ′ include pyridyl group, pyrimidyl group, pyrazyl group, triazyl group, benzothiazole group, benzoxazole group, and benzimidazole group. Quinolyl group, isoquinolyl group, quinoxalyl group, phenanthridyl group and the like.

  Examples of the substituent that the compound represented by any one of the formulas (Va), (Vb), and (Vc) may have include a halogen atom such as a fluorine atom; an alkyl group such as a methyl group and an ethyl group Alkenyl groups such as vinyl groups; alkoxycarbonyl groups such as methoxycarbonyl groups and ethoxycarbonyl groups; alkoxy groups such as methoxy groups and ethoxy groups; aryloxy groups such as phenoxy groups and benzyloxy groups; dimethylamino groups and diethylamino groups A diarylamino group such as a diphenylamino group; a carbazolyl group; an acyl group such as an acetyl group; a haloalkyl group such as a trifluoromethyl group; a cyano group and the like.

The carbon number of the substituent is arbitrary as long as the effects of the present invention are not significantly impaired.
However, when the substituent is an alkyl group, the carbon number is usually 1 or more and 6 or less.
When the substituent is an alkenyl group, the carbon number is usually 2 or more and 6 or less.
When the substituent is an alkoxycarbonyl group, the carbon number is usually 2 or more and 6 or less.
Moreover, when a substituent is an alkoxy group, the carbon number is 1 or more and 6 or less normally.
Moreover, when a substituent is an aryloxy group, the carbon number is 6 or more and 14 or less normally.
Moreover, when a substituent is a dialkylamino group, the carbon number is 2 or more and 24 or less normally.
Moreover, when a substituent is a diarylamino group, the carbon number is 12 or more and 28 or less normally.
When the substituent is an acyl group, the carbon number is usually 1 or more and 14 or less.
Moreover, when a substituent is a haloalkyl group, the carbon number is 1 or more and 12 or less normally.

  The above substituents may be linked to each other to form a ring. As a specific example, a substituent of the ring A1 ″ and a substituent of the ring A2 are bonded, or a substituent of the ring A1 ′ and a substituent of the ring A2 ′ are bonded to form one A condensed ring may be formed, such as a 7,8-benzoquinoline group.

  Among the above-described substituents, the substituents of ring A1 ″, ring A1 ′, ring A2 and ring A2 ′ are more preferably alkyl groups, alkoxy groups, aromatic hydrocarbon groups, cyano groups, halogen atoms, haloalkyl groups. , Diarylamino group and carbazolyl group. In addition, as for the substituents of ring A1 ″, ring A1 ′, ring A2 and ring A2 ′, only one may be substituted or two or more may be in any combination. And may be substituted by a ratio.

In addition, preferable examples of M ^{4 to} M ⁶ in the formulas (Va), (Vb), and (Vc) include ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum, or gold.

  Specific examples of the organometallic complex represented by any one of the above formulas (V), (Va), (Vb) and (Vc) are shown below. However, it is not limited to the following compounds.

  Further, among the organometallic complexes represented by the above formula (V), in particular, as the ligand L and / or L ′, a 2-arylpyridine-based ligand (that is, 2-arylpyridine, an arbitrary substituent group) And a compound having an arbitrary group condensed thereto) are preferable.

  The compounds described in International Publication No. 2005/019373 pamphlet can also be used as the light emitting material.

Next, the compound represented by formula (VI) will be described.
In the formula (VI), M ⁷ represents a metal. Specific examples include the metals described above as the metal selected from Groups 7 to 11 of the periodic table. Among these, ruthenium, rhodium, palladium, silver, rhenium, osmium, iridium, platinum or gold is preferable, and divalent metals such as platinum and palladium are particularly preferable.

In the formula (VI), R ⁹² and R ⁹³ each independently represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, a cyano group, an amino group, an acyl group, an alkoxycarbonyl group, a carboxyl group, It represents at least one selected from the group consisting of an alkoxy group, an alkylamino group, an aralkylamino group, a haloalkyl group, a hydroxyl group, an aryloxy group, an aromatic hydrocarbon group, and an aromatic heterocyclic group. Each R ⁹² and R ⁹³ may be the same or different.

Further, when T is a carbon atom in the formula (VI), R ⁹⁴ and R ⁹⁵ each independently represent a substituent represented by the same examples as R ⁹² and R ⁹³ . Further, in the formula (VI), when T is a nitrogen atom, R ⁹⁴ and R ⁹⁵ are absent. Each T may be the same or different.

In the formula (VI), R ^{92 to} R ⁹⁵ may further have a substituent. When it has a substituent, there is no restriction | limiting in particular in the kind, Arbitrary groups can be made into a substituent. Moreover, as for the substituent, only 1 may be substituted and 2 or more may be substituted by arbitrary combinations and ratios.
Furthermore, in the formula (VI), any two or more groups out of R ^{92 to} R ⁹⁵ may be connected to each other to form a ring.

  Specific examples (T-1 to T-7) of the organometallic complex represented by the formula (VI) are shown below. However, it is not limited to the following examples. In the following chemical formulae, Me represents a methyl group, and Et represents an ethyl group.

  The molecular weight of the compound used as the light emitting material is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 10,000 or less, preferably 5000 or less, more preferably 4000 or less, still more preferably 3000 or less, and usually 100 or more, Preferably it is 200 or more, More preferably, it is 300 or more, More preferably, it is the range of 400 or more. If the molecular weight is too small, the heat resistance is remarkably reduced, gas generation is caused, the layer quality is deteriorated when the layer is formed, or the morphology of the organic electroluminescent element is changed due to migration or the like. There is a case to do. On the other hand, if the molecular weight is too large, it tends to be difficult to purify the organic compound, or it may take time to dissolve in the solvent.

  In addition, any 1 type may be used for the luminescent material mentioned above, and 2 or more types may be used together by arbitrary combinations and a ratio.

  The ratio of the light emitting material in the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.05% by weight or more, preferably 0.3% by weight or more, more preferably 0.5% by weight or more. In addition, it is usually 35% by weight or less, preferably 25% by weight or less, and more preferably 20% by weight or less. If the amount of the light emitting material is too small, uneven light emission may occur. If the amount is too large, the light emission efficiency may be reduced. In addition, when using together 2 or more types of luminescent material, it is made for the total content of these to be contained in the said range.

<3-5-1-2. Hole-transporting compound>
Further, the light emitting layer 5 may contain a hole transporting compound as a constituent material. Here, among examples of the hole transporting compound, examples of the low molecular weight hole transporting compound include <2-3-1-3. In addition to the various compounds exemplified in the column of low molecular weight hole transporting compound>, for example, two represented by 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl Aromatic diamines containing the above tertiary amines and having two or more condensed aromatic rings substituted with nitrogen atoms (Japanese Patent Laid-Open No. 5-234861), 4,4 ′, 4 ″ -tris (1-naphthylphenylamino) Aromatic amine compounds having a starburst structure such as triphenylamine (Journal of Luminescence, 1997, Vol. 72-74, pp. 985), aromatic amine compounds composed of tetramers of triphenylamine (Chemical Communications, 1996, pp. 2175), 2,2 ′, 7,7′-tetrakis- (diphenylamino) -9. 9'-spirobifluorene such spiro compounds of (Synthetic Metals, 1997 years, Vol.91, pp.209), and the like.
In the light emitting layer 5, only one kind of hole transporting compound may be used, or two or more kinds may be used in any combination and ratio.

  The ratio of the hole transporting compound in the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.1% by weight or more, preferably 0.5% by weight or more, more preferably 1% by weight. In addition, it is usually 65% by weight or less, preferably 50% by weight or less, and more preferably 40% by weight or less. If the amount of the hole transporting compound is too small, it may be easily affected by a short circuit, and if it is too large, the film thickness may be uneven. In addition, when using together 2 or more types of hole transportable compounds, it is made for the total content of these to be contained in the said range.

<3-5-1-3. Electron Transport Compound>
The light emitting layer 5 may contain an electron transporting compound as a constituent material. Here, among the electron transporting compounds, examples of low molecular weight electron transporting compounds include 2,5-bis (1-naphthyl) -1,3,4-oxadiazole (BND), 2,5, -Bis (6 '-(2', 2 "-bipyridyl))-1,1-dimethyl-3,4-diphenylsilole (PyPySPyPy), bathophenanthroline (BPhen), 2,9-dimethyl-4,7 -Diphenyl-1,10-phenanthroline (BCP, bathocuproin), 2- (4-biphenylyl) -5- (p-tertiarybutylphenyl) -1,3,4-oxadiazole (tBu-PBD), 4 , 4′-bis (9-carbazole) -biphenyl (CBP), etc. In the light emitting layer 5, only one type of electron transporting compound may be used, or two or more types may be combined arbitrarily. It may be used in combination with not proportion.

  The ratio of the electron transporting compound in the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.1% by weight or more, preferably 0.5% by weight or more, more preferably 1% by weight or more. In addition, it is usually 65% by weight or less, preferably 50% by weight or less, and more preferably 40% by weight or less. If the amount of the electron transporting compound is too small, it may be easily affected by a short circuit, and if it is too large, the film thickness may be uneven. In addition, when using together 2 or more types of electron transport compounds, it is made for the total content of these to be contained in the said range.

<3-5-2. Formation of light emitting layer>
There is no restriction | limiting in the formation method of the light emitting layer 5, As long as the effect of this invention is not impaired remarkably, arbitrary well-known methods can be used. A wet film formation method may be performed, or an evaporation method may be used. Further, the light emitting layer 5 is formed through the film forming process and the drying process described above.

  The thickness of the light emitting layer 5 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 3 nm or more, preferably 5 nm or more, and usually 200 nm or less, preferably 100 nm or less. If the thickness of the light emitting layer 5 is too thin, the function of the light emitting layer 5 may be lowered, and if it is too thick, the driving voltage of the organic electroluminescent element may be increased.

<3-6. Hole blocking layer>
The hole blocking layer 6 is provided on the light emitting layer 5. The hole blocking layer 6 prevents holes moving from the light emitting layer 5 from reaching the electron transport layer 7, the electron injection layer 8, or the cathode 9. It has a role of increasing the probability of recombination with electrons and confining the generated excitons in the light emitting layer 5 and a role of efficiently transporting electrons injected from the cathode 9 toward the light emitting layer 5.
Note that the hole blocking layer 6 may be omitted.

The physical properties required for the material constituting the hole blocking layer 6 include high electron mobility, low hole mobility, a large energy gap (difference between HOMO and LUMO), and excited triplet level (T1). Is high. Examples of the material of the hole blocking layer 6 satisfying such conditions include, for example, bis (2-methyl-8-quinolinolato), (phenolato) aluminum, bis (2-methyl-8-quinolinolato), (triphenylsilanolato). ) Mixed ligand complexes such as aluminum, metal complexes such as bis (2-methyl-8-quinolato) aluminum-μ-oxo-bis- (2-methyl-8-quinolinato) aluminum binuclear metal complexes, distyrylbiphenyl Derivatives such as styryl compounds (JP-A-11-242996), 3- (4-biphenylyl) -4-phenyl-5 (4-tert-butylphenyl) -1,2,4-triazole and other triazole derivatives ( JP-A-7-41759), phenanthroline derivatives such as bathocuproine (JP-A-10-79297), etc. It is below. Further, a compound having at least one pyridine ring substituted at the 2,4,6-position described in International Publication No. 2005-022962 is also preferable as the material for the hole blocking layer 6.
In addition, the material of the hole-blocking layer 6 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  There is no restriction | limiting in the formation method of the hole-blocking layer 6, As long as the effect of this invention is not impaired remarkably, arbitrary well-known methods can be used. A wet film formation method may be performed, or an evaporation method may be used.

  The thickness of the hole blocking layer 6 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.3 nm or more, preferably 0.5 nm or more, and usually 100 nm or less, preferably 50 nm or less. If the film is too thin, defects tend to occur in the film. As a result, holes may flow from the defects and cause deterioration, which may reduce the function of the hole blocking layer 6. If it is too thick, the driving voltage of the organic electroluminescent element 10 may increase.

<3-7. Electron transport layer>
The electron transport layer 7 is formed on the hole blocking layer 6 and on the light emitting layer 5 when the hole blocking layer 6 is not present. The electron transport layer 7 is provided for the purpose of further improving the light emission efficiency of the organic electroluminescent element 10, and electrons injected from the cathode 9 between the electrodes to which an electric field is applied are efficiently directed in the direction of the light emitting layer 5. Formed from compounds that can be transported to
In addition, the structure which excluded the electron carrying layer 7 may be sufficient.

As an electron transporting compound used for the electron transport layer 7, usually, the electron injection efficiency from the cathode 9 or the electron injection layer 8 is high, and the injected electrons having high electron mobility are efficiently transported. The compound which can be used is used. Examples of the compound satisfying such conditions include metal complexes such as aluminum complexes of 8-hydroxyquinoline (JP 59-194393 A), metal complexes of 10-hydroxybenzo [h] quinoline, oxadiazole derivatives , Distyrylbiphenyl derivatives, silole derivatives, 3-hydroxyflavone metal complexes, 5-hydroxyflavone metal complexes, benzoxazole metal complexes, benzothiazole metal complexes, trisbenzimidazolylbenzene (US Pat. No. 5,645,948), quinoxaline compounds ( JP-A-6-207169), phenanthroline derivative (JP-A-5-331459), 2-t-butyl-9,10-N, N'-dicyanoanthraquinonediimine, n-type hydrogenated amorphous silicon carbide , N-type zinc sulfide, n-type Sele Zinc oxide and the like.
In addition, the material of the electron carrying layer 7 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  There is no restriction | limiting in the formation method of the electron carrying layer 7, As long as the effect of this invention is not impaired remarkably, arbitrary well-known methods can be used. A wet film formation method may be performed, or an evaporation method may be used.

  The thickness of the electron transport layer 7 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less. If it is too thin, the electric field quenching of the electron transport layer 7 may occur, and if it is too thick, the driving voltage of the organic electroluminescent element 10 may increase.

<3-8. Electron injection layer>
In the case where the electron injection layer 8 is configured not to include the electron transport layer 7 but to the hole blocking layer 6 on the electron transport layer 7, the electron transport layer 7 and the hole blocking layer are formed on the hole blocking layer 6. In the case of a configuration that does not include the layer 6, it is formed on the light emitting layer 5. The electron injection layer 8 is provided for the purpose of efficiently injecting electrons injected from the cathode 9 into the light emitting layer 5.
A configuration in which the electron injection layer 8 is omitted may be employed.

  In order to perform electron injection efficiently, the material for forming the electron injection layer 8 is preferably a metal having a low work function. Examples include alkali metals such as sodium and cesium, and alkaline earth metals such as barium and calcium. The film thickness is usually preferably from 0.1 nm to 5 nm.

Furthermore, an organic electron transport compound represented by a metal complex such as a nitrogen-containing heterocyclic compound such as bathophenanthroline or an aluminum complex of 8-hydroxyquinoline is doped with an alkali metal such as sodium, potassium, cesium, lithium or rubidium ( (As described in JP-A-10-270171, JP-A-2002-1000047, JP-A-2002-1000048, etc.), it is possible to improve the electron injection / transport properties and achieve excellent film quality. preferable. In this case, the film thickness is usually 5 nm or more, preferably 10 nm or more, and is usually 200 nm or less, preferably 100 nm or less.
In addition, the material of the electron injection layer 8 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  There is no restriction | limiting in the formation method of the electron injection layer 8, As long as the effect of this invention is not impaired remarkably, arbitrary well-known methods can be used. A wet film formation method may be performed, or an evaporation method may be used.

  The thickness of the electron injection layer 8 is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 0.01 nm or more, preferably 0.1 nm or more, and usually 10 nm or less, preferably 5 nm or less. . If it is too thin, the voltage will increase, and the function of the electron injection layer 8 may be reduced. If it is too thick, the organic electroluminescent element 10 may not emit light.

<3-9. Cathode>
A cathode 9 is formed on each of the layers exemplified above. The cathode 9 injects electrons into a layer (such as the electron injection layer 8) on the light emitting layer 5 side.

As the material of the cathode 9, the material used for the anode 2 can be used. However, in order to perform electron injection efficiently, a metal having a low work function is preferable. For example, tin, magnesium, indium, A suitable metal such as calcium, aluminum, silver, or an alloy thereof is used. Specific examples include low work function alloy electrodes such as magnesium-silver alloy, magnesium-indium alloy, and aluminum-lithium alloy.
In addition, the material of the cathode 9 may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

The thickness of the cathode 9 is usually the same as that of the anode 2.
Further, for the purpose of protecting the cathode 9 made of a low work function metal, it is preferable to further stack a metal layer having a high work function and stable to the atmosphere because the stability of the organic electroluminescent element 10 is increased. For this purpose, for example, metals such as aluminum, silver, copper, nickel, chromium, gold and platinum are used. In addition, these materials may be used only by 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

<3-10. Other layers>
The organic electroluminescent device 10 having the layer configuration shown in FIG. 1 has been described above, but the organic electroluminescent device according to the present invention may have another configuration without departing from the spirit of the organic electroluminescent device. . For example, as long as the performance is not impaired, an arbitrary layer may be provided between the anode 2 and the cathode 9 in addition to the layers described above, and an arbitrary layer may be omitted. .

<3-10-1. Electron blocking layer>
The electron blocking layer is provided between the hole transport layer 4 and the light emitting layer 5, or between the hole injection layer 3 and the light emitting layer 5 in the case where the hole transport layer 4 is not provided. The electron blocking layer prevents electrons moving from the light emitting layer 5 from reaching the hole transport layer 4 and the hole injection layer 3, thereby recombining holes and electrons in the light emitting layer 5. There is a role of increasing the probability and confining the generated excitons in the light emitting layer 5 and a role of efficiently transporting holes injected from the anode 2 toward the light emitting layer 5. In particular, it is effective when a phosphorescent material or a blue light emitting material is used as the light emitting material.

As a material required for the electron blocking layer, there are a high hole transport property, a large energy gap (difference between HOMO and LUMO), a high excited triplet level (T1), and the like. Furthermore, when the light emitting layer 5 is produced by a wet film formation method, the electron blocking layer is also required to be compatible with the wet film formation. Examples of the material used for such an electron blocking layer include a copolymer of dioctylfluorene and triphenylamine typified by F8-TFB (described in International Publication No. 2004/084260).
In addition, the material of an electron blocking layer may use only 1 type, and may use 2 or more types together by arbitrary combinations and a ratio.

  There is no restriction | limiting in the formation method of an electron blocking layer, As long as the effect of this invention is not impaired remarkably, arbitrary well-known methods can be used. A wet film formation method may be performed, or an evaporation method may be used. Further, the electron blocking layer may be formed through the film forming process and the drying process described above.

  The thickness of the electron blocking layer is arbitrary as long as the effect of the present invention is not significantly impaired, but is usually 1 nm or more, preferably 5 nm or more, and usually 300 nm or less, preferably 100 nm or less. If it is too thin, it may deteriorate due to film defects and holes flowing, so the function of the electron blocking layer may be reduced. If it is too thick, the driving voltage of the organic electroluminescent device may be increased. .

<3-11. Other>
At the interface between the cathode 9 and the light emitting layer 5 or the electron transport layer 7, for example, lithium fluoride (LiF), magnesium fluoride (MgF ₂ ), lithium oxide (Li ₂ O), cesium carbonate (II) (CsCO ₃ ), etc. It is also an effective method to improve the efficiency of the organic electroluminescent device (Applied Physics Letters, 1997, Vol. 70, pp. 152). Japanese Patent Laid-Open No. 10-74586; see IEEE Transactions on Electron Devices, 1997, Vol. 44, pp. 1245; SID 04 Digest, pp. 154, etc.).

  Moreover, in the layer structure demonstrated above, it is also possible to laminate | stack components other than the board | substrate 1 in reverse order. For example, in the case of the layer configuration of FIG. 1, the other components on the substrate 1 are the cathode 9, the electron injection layer 8, the electron transport layer 7, the hole blocking layer 6, the light emitting layer 5, the hole transport layer 4, the positive layer. The hole injection layer 3 and the anode 2 are provided in this order.

  Furthermore, the organic electroluminescent element of the present invention can be configured by laminating components other than the substrate between two substrates, at least one of which is transparent.

In addition, a structure in which a plurality of components (light emitting units) other than the substrate are stacked in a plurality of layers (a structure in which a plurality of light emitting units are stacked) may be employed. In that case, instead of the interface layer between the steps (between the light emitting units) (in the case where the anode is ITO and the cathode is Al, these two layers), for example, a charge made of vanadium pentoxide (V ₂ O ₅ ) or the like. When a generation layer (Carrier Generation Layer: CGL) is provided, a barrier between steps is reduced, which is more preferable from the viewpoint of light emission efficiency and driving voltage.

  Furthermore, the organic electroluminescent device of the present invention may be configured as a single organic electroluminescent device, or may be applied to a configuration in which a plurality of organic electroluminescent devices are arranged in an array, and an anode and a cathode May be applied to a configuration in which are arranged in an XY matrix.

  Each layer described above may contain components other than those described as materials unless the effects of the present invention are significantly impaired.

[4. Advantages of the present invention and mechanisms for obtaining the effects of the present invention]
ADVANTAGE OF THE INVENTION By this invention, in the manufacturing method of the organic electroluminescent element which has the organic layer formed by the wet film-forming method, the manufacturing method which can obtain a long life organic electroluminescent element can be provided. According to the method for producing an organic electroluminescence device of the present invention, a long-life organic electroluminescence device can be obtained, and the long-life organic electroluminescence device can be stably produced.

  However, it is not clear why such an effect is obtained. The inventor infers this as follows.

  Conventionally, a film coated with a solution forms a “thin film” through one-step heating, and the solvent is volatilized and the thin film is formed at the same time. However, a thin film produced by such a method is difficult to be a homogeneous film, and often becomes a device with noticeable light emission unevenness and device deterioration.

  This is because when the solvent is volatilized and the film is formed at the same time, the solvent is trapped inside the film, and the solvent cannot be completely removed. It is thought to do.

  Therefore, even if stepwise heating is used, if the first stage heating is performed at a temperature below the boiling point of the solvent, the solvent remains in the heated film, and the second stage heating is performed. In this case, as described above, it is considered that the volatilization of the solvent and the formation of the thin film are performed simultaneously.

  In the present invention, the solvent is removed to a very small level so that the formation of the thin film is not affected in the first heating step, and the thin film is made into a stable form in the first cooling step. It is considered that Furthermore, since it is a homogeneous film, it is presumed that in the second heating step, a trace amount of remaining solvent can be removed without affecting the thin film.

An organic electroluminescent element having a non-homogeneous thin film is often an element in which uneven emission or deterioration of the element is remarkable. The organic electroluminescence device manufacturing method of the present invention can obtain an organic electroluminescence device having a homogeneous thin film by the above-mentioned expected mechanism, and therefore, dark spots, reduction of bright spots, and uneven light emission can be suppressed. Stable device characteristics (chromaticity, efficiency, lifetime) can be obtained. Therefore, industrial yield is also improved.
From the above, the element manufactured by the method for manufacturing an organic electroluminescent element of the present invention is effective in extending the lifetime and reducing the voltage among the element characteristics, and the effect on the extended lifetime is particularly remarkable. .
The organic electroluminescent element obtained by the production method of the present invention can be suitably used for an organic EL display. The organic EL display can be obtained by a method described in, for example, “Organic EL display” (Ohm, published on August 20, 2004, by Shizushi Tokito, Chiba Adachi, and Hideyuki Murata). Can be formed.

  EXAMPLES Hereinafter, although this invention is demonstrated in detail using an Example, this invention is not limited to a following example, unless it deviates from the summary.

[Example]
<Example 1>
An organic electroluminescent element having the structure shown in FIG. 1 was produced by the following method.

(ITO substrate)
An indium tin oxide (ITO) transparent conductive film deposited to a thickness of 150 nm on a glass substrate 1 (sputtered film product; sheet resistance 15 Ω) is 2 mm wide stripes using normal photolithography and hydrochloric acid etching. The anode 2 was formed by patterning.
The patterned ITO substrate was cleaned in the order of ultrasonic cleaning with an aqueous surfactant solution, water with pure water, and ultrasonic cleaning with isopropyl alcohol, then dried with compressed air, and finally subjected to ultraviolet ozone cleaning for 1 minute.

(Hole injection layer 3)
The hole injection layer 3 was formed by a wet film formation method as follows. The material of the hole injection layer 3 is a polymer having a repeating structure of the following formula (1) (weight average molecular mass 29400, number average molecular weight 12600, glass transition temperature 160 ° C.) 2 wt% as a hole transporting compound, A composition prepared by dissolving 0.8% by weight of 4-isopropyl-4′-methyldiphenyliododium tetrakis (pentafluorophenyl) borate as an electron accepting compound in ethyl benzoate (boiling point: 213 ° C.), This composition was formed on the ITO substrate by spin coating. The spin coating was performed in two stages, the first stage was performed at a spinner rotation number of 500 rpm for 2 seconds, and the second stage was performed at 1500 rpm for 30 seconds.

The deposited layer was dried. First, as a 1st heating process, it heated to 260 degreeC at 25 degreeC / sec, and heated at 260 degreeC for 1 minute. Then, it cooled to room temperature 23 degreeC +/- 1.5 degreeC as a 1st cooling process. Next, as a 2nd heating process, it heated to 260 degreeC with the temperature increase rate of 25 degreeC / sec, and performed drying at 260 degreeC for 3 hours. Finally, it cooled to room temperature again as a 2nd cooling process.
The apparatus used for heating was a hot plate. The heating in the following examples and comparative examples all uses a hot plate.
By the above method, the hole injection layer 3 having a film thickness of 33.1 nm was formed.

(Hole transport layer 4)
The hole transport layer 4 was formed by a wet film formation method as follows. As a material for the hole transport layer 4, a composition in which 0.4% by weight of a polymer having a repeating structure of the following formula (HT-1) is dissolved in dehydrated toluene is prepared, and this composition is formed on the ITO substrate. A film was formed by spin coating. The spin coating was performed in two stages, the first stage was performed at a spinner rotation number of 500 rpm for 2 seconds, and the second stage was performed at 1500 rpm for 30 seconds.

The formed layer was dried at 230 ° C. for 1 hour.
The hole transport layer 4 having a thickness of 20 nm was formed by the above method.

(Light emitting layer 5)
The light emitting layer 5 was formed by a wet film formation method as follows. The light-emitting layer 5 is prepared by mixing materials H-1 and D-1 shown below at a ratio of 100: 10 and dissolving the mixture in dehydrated toluene to prepare a 0.75 wt% composition. Was formed on the ITO substrate by spin coating. The spin coating was performed in two stages, the first stage was performed at a spinner rotation number of 500 rpm for 2 seconds, and the second stage was performed at 1000 rpm for 30 seconds.

The formed layer was dried at 100 ° C. for 1 hour.
The light emitting layer 5 having a film thickness of 45.6 nm was formed by the above method.

(Hole blocking layer 6 / electron transport layer 7)
The hole blocking layer 6 and the electron transport layer 7 were formed by vacuum deposition as follows.
The hole blocking layer 6 was formed using a compound (HB-1) represented by the following formula so as to have a film thickness of 10.0 nm.
The electron transport layer 7 was formed to have a film thickness of 30.0 nm using an aluminum 8-hydroxyquinoline complex (ET-1) represented by the following formula.

(Electron injection layer / cathode)
The element on which the electron transport layer 7 has been deposited is once taken out from the vacuum deposition apparatus into the atmosphere, and used as a cathode deposition mask, a 2 mm wide stripe shadow mask having a shape orthogonal to the ITO stripe as the anode. Was adhered to the element.
Next, this element is installed in another vacuum deposition apparatus, and lithium fluoride (LiF) is formed to a thickness of 1.01 nm as the electron injection layer 8 by the same vacuum deposition method as the hole blocking layer 6 and the like. Next, aluminum was laminated as the cathode 9 so as to have a film thickness of 80.0 nm.

(Element shape)
By the above procedure, an organic electroluminescent element having a light emitting area portion having a size of 2 mm × 2 mm was obtained.

[Comparative example]
<Comparative Example 1>
In the formation of the hole injection layer 3, the organic electroluminescence element was the same as in Example 1 except that the first heating step was heated to 80 ° C. at 25 ° C./sec and heated at 80 ° C. for 1 minute. Got.
The film thickness of the obtained hole injection layer was 35.2 nm.

<Comparative example 2>
In the formation of the hole injection layer 3, the organic layer was formed in the same manner as in Example 1 except that the first heating step, the first cooling step, the second heating step, and the second cooling step were changed as follows. An electroluminescent element was produced.
As a 1st heating process, it heated to 80 degreeC at 25 degreeC / sec, and heated at 80 degreeC for 1 minute. Then, it cooled to room temperature 23 degreeC +/- 1.5 degreeC as a 1st cooling process. Next, as a 2nd heating process, it heated to 80 degreeC with the temperature increase rate of 25 degreeC / sec, and performed drying at 80 degreeC for 3 hours. Finally, as the second cooling step, the hole injection layer 3 having a film thickness of 36.5 nm was formed by cooling to room temperature again.

<Comparative Example 3>
In the formation of the hole injection layer 3, the first heating step and the first cooling step are changed as follows, and the second heating step and the second cooling step are not performed. Similarly, an organic electroluminescent element was produced.
As a 1st heating process, it heated to 80 degreeC at 25 degreeC / second, and heated at 80 degreeC for 3 hours. Then, as a 1st cooling process, it cooled to room temperature 23 degreeC +/- 1.5 degreeC, and formed the hole injection layer 3 with a film thickness of 38.4 nm.

<Comparative example 4>
In the formation of the hole injection layer 3, the first heating step and the first cooling step are changed as follows, and the second heating step and the second cooling step are not performed. Similarly, an organic electroluminescent element was produced.
As a 1st heating process, it heated to 260 degreeC at 25 degreeC / second, and heated at 260 degreeC for 3 hours. Then, as a 1st cooling process, it cooled to room temperature 23 degreeC +/- 1.5 degreeC, and formed the hole injection layer 3 with a film thickness of 35.3 nm.

[Measuring method]
<Luminance half-life>
As a method for measuring the luminance half-life, a change in luminance was observed with a photodiode when a constant direct current with a luminance of 1000 nit at the start of the test was passed through the produced organic electroluminescence device. The time (luminance half-life) until the luminance value reached half of the test start, that is, 500 nit was obtained. The energization test was performed in a room where the room temperature was controlled to 23 ± 1.5 ° C. by air conditioning.

<Drive voltage>
The driving voltage was measured by measuring the voltage at which the luminance was 1000 nit when a constant direct current was first applied to the produced organic electroluminescent device.

[result]
Table 1 below shows the results of the obtained luminance half-life and voltage at 1000 nit drive.

  From these results, it is clear that an organic electroluminescent device having a long lifetime and a low driving voltage can be obtained by using the method for manufacturing an organic electroluminescent device of the present invention. The lifetime of the element having the layer could be extended.

  The present invention relates to various fields in which organic electroluminescent elements are used, for example, light sources (for example, light sources of copiers, flat panel displays (for example, for OA computers and wall-mounted televisions) and surface light emitters). It can be suitably used in the fields of liquid crystal displays and backlights of instruments), display panels, indicator lamps and the like.

It is sectional drawing which shows typically the structure of the organic electroluminescent element which concerns on the Example of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Hole blocking layer 7 Electron transport layer 8 Electron injection layer 9 Cathode 10 Organic electroluminescent device

Claims (7)

A method for producing an organic electroluminescent device having a hole injection layer and / or a hole transport layer and a light emitting layer between an anode and a cathode,
A first heating step in which a composition containing a hole injection material and / or a hole transport material and a solvent is formed, and the formed film is heated at a temperature equal to or higher than the boiling point of the solvent. 1. A method for producing an organic electroluminescent element, wherein the hole injection layer and / or the hole transport layer are formed by passing through a cooling step 1 and a second heating step in this order in this order. 2. The method of manufacturing an organic electroluminescent element according to claim 1, wherein in the second heating step, heating is performed at a temperature rising rate of 3 ° C./second or more and 150 ° C./second or less. The difference between the heating temperature of the first heating step and the cooling temperature of the first cooling step is 100 ° C or more, The manufacture of the organic electroluminescent element according to claim 1 or 2, Method. The method for producing an organic electroluminescent element according to claim 1, wherein the solvent has a boiling point of 110 ° C. or higher and 300 ° C. or lower. The method for producing an organic electroluminescent element according to claim 1, wherein the light emitting layer is formed as a layer made of a low molecular compound by a wet film forming method. The method for producing an organic electroluminescent element according to claim 1, wherein the hole transport material is a thermally crosslinkable compound. An organic EL display comprising the organic electroluminescent element obtained by the method for producing an organic electroluminescent element according to claim 1.

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