JP5242016B2 - COMPOUND FOR ORGANIC EL ELEMENT AND ORGANIC EL ELEMENT - Google Patents

Description

  The present invention relates to a compound for an organic EL device and an organic EL device.

  An organic EL element used in a display device such as an organic EL display has an organic layer such as a light emitting layer containing a light emitting organic material between a hole injection electrode (anode) and an electron injection electrode (cathode), for example. It is. By applying an electric field from the electrode to the light emitting layer, the light emitting organic material is excited and emits light.

  The light emission principle of this organic EL element is generally considered as follows. That is, first, the holes injected from the hole injection electrode and the electrons injected from the electron injection electrode are recombined in the light emitting layer, thereby generating excitons of the light emitting organic material. Then, when the exciton is deactivated, energy is released as a light (fluorescence, phosphorescence) component. This is believed to cause light emission.

  As one method for improving the light emission efficiency of such an organic EL element and suppressing the driving voltage, an organic layer different from the light emitting layer, for example, a hole injection layer is provided between the hole injection electrode and the light emitting layer. A method is mentioned. This makes it possible to smoothly inject holes from the hole injection electrode into the light emitting layer.

Various materials are known as the material of the hole injection layer, and typical examples thereof include, for example, a tetraphenylbenzidine compound disclosed in Patent Document 1 and an N, N′-type di-biphenylamino compound disclosed in Patent Document 2. Compounds. By using these compounds as materials for the hole injection layer, the driving voltage can be suppressed.
JP 2001-273978 A Japanese Patent Laid-Open No. 10-88119

  However, the tetraphenylbenzidine compound of Patent Document 1 has a high crystallinity due to its highly symmetric structure, and has a problem in that it is crystallized in an organic EL element to cause a decrease in light emission rate and an increase in driving voltage. there were. Furthermore, this organic EL element has a problem that the drive voltage cannot be sufficiently suppressed.

  In contrast, in the organic EL device using the N, N′-type di-biphenylamino compound of Patent Document 2, although the driving voltage can be suppressed, the molecular weight is large and the symmetry is high. There has been a problem that a high deposition temperature is required when vacuum deposition is performed to form the organic layer of the organic EL element. That is, when vapor deposition is performed at a high temperature, there is a possibility that the compound is decomposed. When the compound is decomposed, the purity of the compound in the organic layer is lowered, and the resulting organic EL element becomes electrically and chemically unstable, the driving life is reduced, and the driving voltage is increased.

  Therefore, the present invention has been made in view of the above circumstances, and an organic EL capable of sufficiently suppressing a driving voltage and capable of sufficiently lowering a vapor deposition temperature for forming an organic layer. It aims at providing the compound for elements, and the organic electroluminescent element using this compound.

  As a result of intensive studies, the present inventors have found that the above object can be achieved by using a compound represented by the following general formula (1) for an organic EL device.

  That is, this invention provides the compound for organic EL elements represented by following General formula (1).

In the formula (1), Ar represents a divalent group represented by the general formula (a), and R ¹ represents a hydrogen atom or a phenyl group which may have a substituent. R ^{2 to} R ⁴ each independently have an alkyl group having 1 to 4 carbon atoms, an N, N-dialkylamino group having 2 to 8 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a substituent. Or a nitrogen-containing heterocyclic group having 3 to 5 carbon atoms and 1 to 3 carbon atoms. R ^{5 to} R ⁸ each independently represent an alkyl group having 1 to 4 carbon atoms, an N, N-dialkylamino group having 2 to 8 carbon atoms in total, or an alkoxy group having 1 to 4 carbon atoms. n2 to n4 represent 0 or an integer of 1 to 5, and n5 to n8 represent 0 or an integer of 1 to 4. However, when R ¹ is a hydrogen atom, n2 is an integer of 1 to 5, and at least one of R ² is a phenyl group which may have a substituent. In formula (a), R ^{11 to} R ¹³ each independently represents an alkyl group having 1 to 3 carbon atoms, an N, N-dialkylamino group having 2 to 6 carbon atoms in total, or an alkoxy group having 1 to 3 carbon atoms. , M1 to m3 represent 0 or an integer of 1 to 4. However, the general formula (a) excluding R ^{11 to} R ¹³ forms a 4,4 ″ -diamino- [1,1 ′; 4 ′, 1 ″] terphenyl skeleton in the general formula (1). Except when doing.

Here, the above general formula (a) excluding R ^{11 to} R ¹³ is the above general formula (1), wherein the 4,4 ″ -diamino- [1,1 ′; 4 ′, 1 ″] terphenyl skeleton is “Form” means that the general formula (a) has the following skeleton (general formula (a ′)).

  The reason why such a compound for an organic EL device can achieve the object of the present invention is not clarified in detail at present, but the present inventors consider one of the factors as follows. . However, the factor is not limited to this.

  The compound for organic EL devices of the present invention has a p-biphenyl skeleton, as shown in the general formula (1), in which all four or at least three groups bonded to the N—Ar—N skeleton are present. For this reason, it is thought that the compound for organic EL elements of this invention has high hole transportability and high hole injection property compared with the conventional one. Therefore, when such a compound is used as a constituent material of the hole injection layer and / or the hole transport layer provided between the hole injection electrode and the light emitting layer of the organic EL element, the high hole injection property and the transport property are obtained. As a result, it is considered that the adhesion between the hole injection electrode and the hole injection layer and / or the hole transport layer is improved, and the driving voltage is lowered.

  In the compound for an organic EL device of the present invention, the -Ar- group between two nitrogen atoms has a terphenyl structure as shown in the general formulas (1) and (a). As a result, the compound for an organic EL device of the present invention is considered to have a high bulk as compared with a tetraphenylbenzidine compound having a 4,4′-biphenyl structure as an —Ar— group, and thus the driving voltage is considered to be lowered. Further, the compound for an organic EL device of the present invention from which the terphenyl structure represented by the general formula (a ′) is removed has a molecule as compared with the compound in which the —Ar— group is the general formula (a ′). It is considered that vapor deposition can be performed at a sufficiently low temperature when the organic layer of the organic EL element is formed. For this reason, in the compound for organic EL elements of this invention, the high vapor deposition temperature exceeding 400 degreeC which was a problem in the conventional compound for organic EL elements becomes unnecessary, and there is no possibility of accompanying the decomposition | disassembly of a compound.

The compound for an organic EL device of the present invention represents a phenyl group which R ¹ may have a substituent from the viewpoint of further reducing the driving voltage of the organic EL device, and R ^{2 to} R ⁴ and R ⁵ to Preferably, each R ⁸ independently represents an alkyl group having 1 to 4 carbon atoms, an N, N-dialkylamino group having 2 to 8 carbon atoms or a phenyl group which may have a substituent.

  From the viewpoints of maintaining the luminous efficiency and lowering the driving voltage, the compound for an organic EL device of the present invention should preferably have m1 to m3 of 0, and can reduce the deposition temperature. Therefore, the organic EL device compound as a whole preferably has 11 to 13 benzene rings, and more preferably 11 benzene rings.

In the compound for an organic EL device of the present invention, R ¹ is preferably a phenyl group, and n2 to n4 and n5 to n8 are preferably 0. In such a case, it is possible to maintain the luminous efficiency, lower the driving voltage, and lower the vapor deposition temperature.

  The organic EL device of the present invention is an organic EL device including one or more organic layers between two electrodes arranged to face each other, and at least one of the organic layers is the same as described above. Contains compounds for organic EL devices. This makes it possible to manufacture an organic EL element that can achieve the above effects. In order to further reduce the driving voltage of the organic EL element, the organic layer containing the compound for organic EL element is preferably at least one of a hole injection layer, a hole transport layer, and a light emitting layer. More preferably, it is an injection layer.

  ADVANTAGE OF THE INVENTION According to this invention, the compound for organic EL elements which can fully suppress a drive voltage and can make vapor deposition temperature for forming an organic layer low enough (for example, 400 degrees C or less) is possible. And it becomes possible to provide an organic EL element.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as the case may be, but the present invention is not limited to the following embodiments. In the drawings, the same elements are denoted by the same reference numerals, and redundant description is omitted. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. Further, the dimensional ratios in the drawings are not limited to the illustrated ratios.

(Compound for organic EL device)
The compound (organic EL device compound) used in the organic EL device according to a preferred embodiment of the present invention is a tetraaryldiamine derivative represented by the above general formula (1) (hereinafter referred to as “compound (1)” in some cases. ").

Examples of the substituent used in the “optionally substituted phenyl group” of R ¹ in the general formula (1) include, for example, an alkyl group having 1 to 4 carbon atoms, N having 2 to 8 carbon atoms in total, N-dialkylamino group, alkoxy group having 1 to 4 carbon atoms, phenyl group, or nitrogen-containing heterocyclic group having 3 to 5 carbon atoms and 1 to 3 nitrogen atoms, alkyl group having 1 to 4 carbon atoms, total carbon It is preferably an N, N-dialkylamino group or a phenyl group of 2 to 8, and more preferably a methyl group or a phenyl group. Although it does not specifically limit as a substituted position of these substituents, It is more preferable that it is the m-position or p-position of a phenyl group. R ¹ is particularly preferably a phenyl group having no substituent.

The alkyl group having 1 to ⁴ carbon atoms of R ^{2 to} R ⁴ may be linear or branched. Specific examples thereof include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group and t-butyl group.

The N, N-dialkylamino group having 2 to 8 carbon atoms in total from R ^{2 to} R ⁴ may be linear or branched. Specific examples thereof include N, N-dimethylamino group, N, N-diethylamino group, N, N-di-n-propylamino group, N, N-di-i-propylamino group, N, N-di -N-Butylamino group, N, N-di-i-butylamino group, N, N-di-s-butylamino group, N, N-di-t-butylamino group can be mentioned.

An alkoxy group having 1 to 4 carbon atoms R ² to R ⁴ may be linear or branched. Specific examples thereof include a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, an i-butoxy group, an s-butoxy group, and a t-butoxy group.

The substituent in "optionally substituted phenyl group" in R ² to R ^4, is not particularly limited, for example, an alkyl group having 1 to 4 carbon atoms, the total carbon number 2-8 N, N-dialkylamino group, alkoxy group having 1 to 4 carbon atoms, phenyl group, or nitrogen-containing heterocyclic group having 3 to 5 carbon atoms and 1 to 3 nitrogen atoms, alkyl group having 1 to 4 carbon atoms, total carbon It is preferably an N, N-dialkylamino group or a phenyl group of 2 to 8, and more preferably a methyl group or a phenyl group. Although it does not specifically limit as a substituted position of these substituents, It is more preferable that it is the m-position or p-position of a phenyl group.

  The nitrogen-containing heterocyclic group having 3 to 5 carbon atoms and 1 to 3 carbon atoms is not particularly limited, and examples thereof include an imidazolyl group, a pyridyl group, and a pyrrolyl group.

The alkyl group having 1 to 4 carbon atoms of R ^{5 to} R ⁸ , the N, N-dialkylamino group having 2 to 8 carbon atoms or the alkoxy group having 1 to 4 carbon atoms has the same meaning as in the case of R ^{2 to} R ^4. is there. R ^{5 to} R ⁸ are preferably an alkyl group having 1 to 4 carbon atoms, an N, N-dialkylamino group having 2 to 8 carbon atoms, or an optionally substituted phenyl group, a methyl group or a phenyl group. It is more preferable that

Examples of the alkyl group having 1 to 3 carbon atoms of R ^{11 to} R ¹³ include a methyl group, an ethyl group, an n-propyl group, and an i-propyl group. Examples of the N 2, N-dialkylamino group having 2 to 6 carbon atoms in total of R ^{11 to} R ¹³ include N, N-dimethylamino group, N, N-diethylamino group, N, N-di-n-propylamino group. Group, N, N-di-i-propylamino group.

Examples of the alkoxy group having 1 to 3 carbon atoms of R ^{11 to} R ¹³ include a methoxy group, an ethoxy group, an n-propoxy group, and an i-propoxy group.

  m1 to m3 are preferably 0 from the viewpoint of maintaining luminous efficiency and further reducing the driving voltage.

  n2 to 4 are preferably 0 or 1 from the viewpoint of maintaining luminous efficiency and lowering the driving voltage, and more preferably 0 from the viewpoint of lowering the sublimation temperature.

  n5 to n8 are preferably 0 from the viewpoint of maintaining luminous efficiency and further reducing the driving voltage.

  The number of benzene rings in the compound (1) is preferably 11 to 13 and more preferably 11 from the viewpoint that the deposition temperature can be lowered. Moreover, it is preferable that the molecular weight of a compound (1) is 1000 or less from a viewpoint of making sublimation temperature low.

  As the bonding position in formula (a), from the viewpoint of lowering the driving voltage, in the benzene ring having a bond with the adjacent benzene ring and the nitrogen atom, the carbon and the adjacent nitrogen atom in the adjacent benzene ring are in the para position. Most preferably, it is bonded to a benzene ring.

  Compound (1) is produced, for example, by the two methods described below.

(A) Secondary amine represented by the following general formula (a) (Ar ² and Ar ³ each independently represents a phenyl group, a biphenyl group, a terphenyl group, etc.) and the following general formula (b) A disubstituted benzene represented (in formula (b), X ¹ represents a bromine atom, an iodine atom, or a trifluoromethanesulfonyloxy group (—OSO ₂ CF ₃ )) is reacted with the following general formula (c ) And lithiated the substituted arylamine with n-butylamine or the like, and then a borated reagent (for example, triethyl borate, 2-isopropoxy-4,4,5,5-tetra A boric acid (or boric acid ester) compound of an arylamine represented by the following general formula (d) (wherein R is hydrogen) Atom or atom Represents a cycloalkyl group or the like).

Finally, a boric acid (or borate ester) compound of the arylamine and a disubstituted benzene represented by the following general formula (e) (in the formula (e), X ² and X ³ are each independently a bromine atom. , An iodine atom, or a trifluoromethanesulfonyloxy group (—OSO ₂ CF ₃ )) is cross-coupled in the presence of a palladium catalyst and a base to obtain the target compound represented by the formula (7). It is done. In addition, the reaction scheme based on the manufacturing method of (A) is as follows.

(B) Secondary amine represented by the following general formula (f) (Ar ² and Ar ³ each independently represents a phenyl group, a biphenyl group, a terphenyl group, etc.) and the following general formula (g) (in the formula (g), ^{X 4} is. representing a bromine atom, an iodine atom or trifluoromethanesulfonyloxy group (-OSO ₂ CF ₃₎₎ disubstituted benzene represented by reacting the following general formula (h ), And after lithiation with n-butyllithium or the like, the substituted arylamine is borated with a borated reagent to form an arylamine boron represented by the following general formula (i). An acid (or borate ester) compound is obtained. A boric acid (or borate ester) compound of the arylamine (in the formula (d), R represents a hydrogen atom or a cycloalkyl group) and a disubstituted benzene represented by the following general formula (j) (formula ( In e), X ⁵ and X ⁶ each independently represent a bromine atom, an iodine atom, or a trifluoromethanesulfonyloxy group (—OSO ₂ CF ₃ )) and a cross-coupling in the presence of a palladium catalyst and a base. Thus, a substituted arylamine represented by the following general formula (k) is obtained.

Next, a secondary amine represented by the following general formula (l) (in the formula (l), Ar ⁴ and Ar ⁵ represent a biphenyl group and the like) and a disubstituted group represented by the following general formula (m) Benzene (in formula (m), X ⁷ represents a bromine atom, an iodine atom, or a trifluoromethanesulfonyloxy group (—OSO ₂ CF ₃ )) and is represented by the following general formula (n). A substituted arylamine compound is obtained, and the substituted arylamine is lithiated with n-butyllithium or the like, then borated with a borated reagent, and boric acid (or boronic acid) of the arylamine represented by the following general formula (o) is obtained. Acid ester) compound (in the formula (o), R represents a hydrogen atom or a cycloalkyl group).

  Finally, a substituted arylamine compound represented by the following general formula (k) and a boric acid (or borate ester) compound of an arylamine represented by the following general formula (o) are cross-cups in the presence of a palladium catalyst. By ringing, the target compound represented by the formula (8) is obtained. In addition, the reaction scheme based on the manufacturing method of (B) is as follows.

As specific examples of the compound (1), combinations of Ar, R ^{1 to} R ⁸ , R ^{11 to} R ¹³ , n2 to n8 and m1 to m3 in the general formula (1) are shown in Tables 1 to 75 below, respectively. Compound Nos. (I-1) to (I-300), (II-1) to (II-300), (III-1) to (III-300), (IV-1) to (IV-300) ) And (V-1) to (V-300), but are not limited thereto. However, in the table, Me is methyl group, Et is ethyl group, ⁿ Pr is n-propyl group, ⁱ Pr is i-propyl group, ⁿ Bu is n-butyl group, ⁱ Bu is i-butyl group, and ^s Bu is s- butyl ^group, t Bu is t- butyl group, Ph represents respectively a phenyl group.

(Organic EL device)
FIG. 1 is a schematic cross-sectional view showing a first embodiment of an organic EL element according to the present invention. An organic EL element 100 shown in FIG. 4 includes a hole injection layer 14, a hole transport layer 11, a light emitting layer 10, and two electrodes (a first electrode 1 and a second electrode 2) arranged to face each other. The electron injection layer 13 is sandwiched. The hole injection layer 14, the hole transport layer 11, the light emitting layer 10, and the electron injection layer 13 are all organic layers, and are stacked in this order from the first electrode 1 side. The electron injection layer 13 can be an inorganic layer (metal layer, metal compound layer, etc.) (the same applies hereinafter).

  FIG. 2 is a schematic cross-sectional view showing a second embodiment of the organic EL element according to the present invention. An organic EL element 200 shown in FIG. 2 has a structure in which an electron transport layer 12 is provided between the electron injection layer 13 and the light emitting layer 10 of the organic EL element 100 in FIG.

  FIG. 3 is a schematic cross-sectional view showing a third embodiment of the organic EL element according to the present invention. The organic EL element 300 shown in FIG. 3 has a structure in which the light emitting layer 10 of the organic EL element 200 in FIG. 2 is replaced with a first light emitting layer 10a and a second light emitting layer 10b.

  In the first to third embodiments, the first electrode 1 is formed on the substrate 4, but the stacking order from the substrate 4 side may be reversed. That is, in the case of the organic EL element of the first embodiment, the second electrode 2, the electron injection layer 13, the light emitting layer 10, the hole transport layer 11, the hole injection layer 14, and the first electrode 1 are arranged in this order from the substrate 4 side. May be laminated. The compound for an organic EL device of the present invention is preferably contained in at least one of the hole injection layer 14, the hole transport layer 11 and the light emitting layer 10 described above, and is contained in the hole injection layer 14. Most preferred.

  In the above embodiment, the first electrode 1 and the second electrode 2 function as a hole injection electrode (anode) and an electron injection electrode (cathode), respectively. While holes (holes) are injected and electrons are injected from the second electrode 2, the organic EL element compound in the light emitting layer emits light based on these recombination.

  The preferred thicknesses of the light emitting layer, hole transport layer, electron transport layer, hole injection layer and hole transport layer are all 5 to 200 nm.

(substrate)
The substrate 4 can be used without particular limitation as long as it is provided in a conventional organic EL element, and is an amorphous substrate such as glass or quartz, Si, GaAs, ZnSe, ZnS, GaP, A crystal substrate such as InP or a metal substrate such as Mo, Al, Pt, Ir, Au, Pd, or SUS can be used. Further, a thin film made of a crystalline or amorphous ceramic, metal, organic substance or the like formed on a predetermined substrate may be used.
When the substrate 4 side is the light extraction side, it is preferable to use a transparent substrate such as glass or quartz as the substrate 4, and it is particularly preferable to use an inexpensive glass transparent substrate. The transparent substrate may be provided with a color filter film, a color conversion film containing a fluorescent material, a dielectric reflection film, or the like for adjusting the color light.

(First electrode)
The first electrode 1 functions as a hole injection electrode (anode). Therefore, the material of the first electrode 1 is not particularly limited as long as it is provided in the conventional organic EL element, but it can be efficiently applied to a layer adjacent to the first electrode 1 and A material that can uniformly apply an electric field is preferable.

  When the substrate 4 side is the light extraction side, the transmittance at a wavelength of 400 to 700 nm, which is the emission wavelength region of the organic EL element, particularly the transmittance of the first electrode 1 at the wavelength of each RGB color is 50% or more. Preferably, it is 80% or more, more preferably 90% or more. When the transmittance of the first electrode 1 is less than 50%, the light emission from the light emitting layer 10 is attenuated, and it is difficult to obtain the luminance necessary for image display.

The 1st electrode 1 with comparatively high light transmittance can be comprised using the transparent conductive film comprised with various oxides. As such a material, indium oxide (In ₂ O ₃ ), tin oxide (SnO ₂ ), zinc oxide (ZnO), tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), and the like are preferable. It is particularly preferable in that a thin film having a uniform in-plane specific resistance can be easily obtained.

  The film thickness of the first electrode 1 is preferably determined in consideration of the above-described light transmittance. For example, when using an oxide transparent conductive film, the film thickness is preferably 10 to 500 nm, more preferably 30 to 300 nm. When the film thickness of the first electrode 1 exceeds 500 nm, the light transmittance may be insufficient and the first electrode 1 may be peeled off from the substrate 4 in some cases. Further, although the light transmittance is improved as the film thickness is decreased, when the film thickness is less than 10 nm, the resistivity is increased and the driving voltage of the organic EL element tends to be increased.

(Second electrode)
The second electrode 2 functions as an electron injection electrode (cathode). The material of the second electrode 2 is not particularly limited as long as it is provided in a conventional organic EL element, and examples thereof include a metal material, an organometallic complex, or a metal compound. It is preferable to use a material having a relatively low work function so that electrons can be efficiently and reliably injected into the substrate 10 and may be transparent.

  Specific examples of the metal material constituting the second electrode 2 include alkali metals such as Li, Na, K or Cs, alkaline earth metals such as Mg, Ca, Sr or Ba, or Al (aluminum). . Alternatively, a metal having properties similar to those of an alkali metal or alkaline earth metal such as La, Ce, Sn, Zn, or Zr can be used. Furthermore, oxides or halides of the above metal materials can also be used. Further, it may be a mixture or alloy containing the above materials, and a plurality of these may be laminated.

  The film thickness of the second electrode 2 only needs to be such that electrons can be uniformly injected, and may be 0.1 nm or more.

  An auxiliary electrode may be provided on the second electrode 2. Thereby, the electron injection efficiency to the light emitting layer 10 grade | etc., Can be improved, and the penetration | invasion of the water | moisture content or the organic solvent to the light emitting layer 10 or the electron injection layer 13 can be prevented. As a material for the auxiliary electrode, a general metal can be used because there is no restriction on work function and charge injection capability. However, it is preferable to use a metal having high conductivity and easy handling. In particular, in the case where the second electrode 2 includes an organic material, it is preferable to select appropriately according to the type and adhesion of the organic material.

  Examples of the material used for the auxiliary electrode include Al, Ag, In, Ti, Cu, Au, Mo, W, Pt, Pd, and Ni. Among them, when a low-resistance metal such as Al and Ag is used, electrons are used. The injection efficiency can be further increased. Moreover, higher sealing properties can be obtained by using a metal compound such as TiN. These materials may be used alone or in combination of two or more. Moreover, when using 2 or more types of metals, you may use as an alloy. Such an auxiliary electrode can be formed by, for example, a vacuum deposition method or the like.

(Hole injection layer)
As a material for the hole injection layer 14, the compound for an organic EL element of the present embodiment described above, that is, the compound (1) is used. An organic EL element provided with such a hole injection layer 14 has sufficiently superior light emission efficiency and can sufficiently suppress a decrease in driving voltage as compared with a conventional organic EL element.

  The hole injection layer 14 may contain the compound (1) alone as a constituent material, contains the compound (1) as a main component material, and is further used as a material for a conventional hole transport layer. 1 type, or 2 or more types may be contained. Examples of such materials include low molecular weight materials such as pyrazoline derivatives, arylamine derivatives, stilbene derivatives, and triphenyldiamine derivatives. Further, the hole injection layer 14 may be subjected to heat treatment at a temperature equal to or higher than the glass transition temperature (Tg) of the constituent material.

  The content ratio of materials other than the compound (1) in the hole injection layer 14 is preferably 10% or less on a volume basis from the viewpoint of improving luminous efficiency, driving voltage and / or driving life, and is 5% or less. And more preferred.

(Hall transport layer)
For the hole transport layer, any of a low molecular material and a high molecular material can be used, and the compound may contain the compound (1). Examples of the hole transporting low molecular weight material include pyrazoline derivatives, arylamine derivatives, stilbene derivatives, and triphenyldiamine derivatives. Also, hole transporting polymer materials include polyvinyl carbazole (PVK), polyethylenedioxythiophene (PEDOT), polyethylenedioxythiophene / polystyrene sulfonic acid copolymer (PEDOT / PSS), polyaniline / polystyrene sulfonic acid copolymer. (Pani / PSS). As a constituent material of the hole transport layer, the compound (1) may be used alone, containing the compound (1) as a main component material, and further containing one or more hole transport materials. It may be.

(Light emitting layer)
The material of the light emitting layer 10 is not particularly limited as long as it is an organic compound that generates excitons by recombination of electrons and holes and emits light when the excitons release energy and return to the ground state. Can be used without any problem. Specifically, for example, organometallic complex compounds such as aluminum complex, beryllium complex, zinc complex, iridium complex or rare earth metal complex, anthracene, naphthacene, benzofluoranthene, naphthofluoranthene, styrylamine or tetraaryldiamine or These derivatives, low molecular organic compounds such as perylene, quinacridone, coumarin, DCM or DCJTB, or π-conjugated polymers such as polyacetylene derivatives, polyphenylene vinylene derivatives, polyfluorene derivatives or polythiophene derivatives, or polyvinyl compounds, polystyrene derivatives, Non-π conjugated side chain polymers or main chain polymers such as polysilane derivatives, polyacrylate derivatives or polymethacrylate derivatives, etc. And high molecular organic compounds. Further, the compound (1) may be contained as a constituent material.

(Electron transport layer)
As the material of the electron transport layer 12, any conventionally known material can be used without particular limitation, and any electron transport material of a low molecular weight material and a high molecular weight material can be used. Examples of the electron transporting low molecular weight material include oxadiazole derivatives, imidazopyridine derivatives, anthraquinodimethane and its derivatives, benzoquinone and its derivatives, naphthoquinone and its derivatives, anthraquinone and its derivatives, tetracyanoanthraquinodimethane and Examples thereof include fluorene and derivatives thereof, diphenyldicyanoethylene and derivatives thereof, phenanthroline and derivatives thereof, and metal complexes having these compounds as ligands. Examples of the electron transporting polymer material include polyquinoxaline and polyquinoline. As the material for the electron transport layer 12, one type may be used alone, or two or more types may be used in combination.

(Electron injection layer)
The constituent material of the electron injection layer 13 is not particularly limited as long as it is used for the electron injection layer in the conventional organic EL element, and an alkali metal such as lithium, lithium fluoride, lithium oxide or the like is used. be able to. By providing this electron injection layer 13, the organic EL element facilitates injection of electrons from the second electrode (electron injection electrode) 2, stably transports electrons, and further holes from the organic light emitting layer 10. It will have a function to prevent. Thereby, the luminous efficiency of the organic EL element is improved and the driving voltage tends to decrease as a whole.

  The organic EL device according to this embodiment can be manufactured by a known manufacturing method except that the hole injection layer 14 is formed using the compound (1). As a method for forming each organic layer including such a hole injection layer 14, a vacuum vapor deposition method, an ionization vapor deposition method, a coating method, or the like can be appropriately selected and employed depending on the material constituting the organic layer.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

(Synthesis Example 1)
Synthesis of N, N, N ′, N′-tetrakis- (p-biphenyl)-[1,1 ′; 3 ′, 1 ″]-terphenyl-4,4 ″ -diamine (compound (I)) The title compound was synthesized by the following method according to the following reaction formula.

  20.0 g (0.062 mol) of bis- (p-biphenyl) amine, 52.8 g (0.186 mol) of 1-bromo-4-iodobenzene, and 25.8 g (0.186 mol) of anhydrous potassium carbonate Then, 6.0 g (0.094 mol) of copper powder and 40 mL of decahydronaphthalene were mixed and reacted at 180 to 200 ° C. for about 40 hours. Next, the reaction product was extracted with 700 mL of toluene, washed with water, and purified by column chromatography (carrier: silica gel, eluent: toluene / n-hexane = 1/2 (volume ratio)). Bis- (p-biphenyl) ) -4-bromophenylamine (hereinafter referred to as compound (I-1)) 15.4 g (yield 52%) was obtained.

  To a mixed solution of 15.0 g (0.032 mol) of the above compound (I-1) and 120 mL of tetrahydrofuran was added 24.0 mL (0.038 mol) of a 1.57 mol / L n-butyllithium-hexane solution. The mixture was reacted at -78 ° C for about 1 hour. Then, 17.9 g (0.096 mol) of 2-isopropoxy-4,4,5,5-tetramethyl- [1,3,2] dioxaborolane was added and reacted for about 6 hours. The reaction product was extracted with 500 mL of toluene, washed with water, and purified by column chromatography (carrier: silica gel, eluent: toluene / n-hexane = 5/1 (volume ratio)). Bis- (p-biphenyl) 7.38 g (44% yield) of -4- (4,4,5,5-tetramethyl- [1,3,2] dioxaborolanyl) phenylamine (hereinafter referred to as compound (I-2)) )was gotten.

  3.5 g (0.0067 mol) of the above compound (I-2), 0.65 g (0.0028 mol) of m-dibromobenzene, 0.19 g (0.00017) of tetrakis (triphenylphosphine) palladium (0) Mol), 40 mL of a 2M aqueous sodium carbonate solution, 20 mL of ethanol, and 80 mL of toluene were mixed and reacted at 80 to 90 ° C. for about 10 hours. Next, the reaction product was extracted with 400 mL of toluene, washed with water, and purified by column chromatography (carrier: silica gel, eluent: toluene / n-hexane = 3/1 (volume ratio)) to obtain compound (I). 2.43 g (yield 78%) was obtained. This was further purified by sublimation to obtain Compound (I) having a purity of 99.98% (purity confirmed by high performance liquid chromatography (HPLC)).

As a result of mass spectrometry of the obtained compound, a peak was confirmed at m / e = 869 as shown in FIG. Moreover, when this compound was analyzed using the infrared absorption spectroscopy (IR) method, IR spectrum shown in FIG. 5 was obtained. Furthermore, Analysis of this compound ¹ H- using nuclear magnetic resonance ⁽¹ H-NMR) method, obtained NMR spectrum shown in FIG. ^6, 13 C-nuclear using magnetic resonance ⁽¹³ C-NMR) method As a result, the NMR spectrum shown in FIG. 7 was obtained. From these results, it was confirmed that the compound obtained in Synthesis Example 1 was compound (I).

(Synthesis Example 2)
Synthesis of N, N, N ′, N′-tetrakis- (p-biphenyl)-[1,1 ′; 3 ′, 1 ″]-terphenyl-3,3 ″ -diamine (compound (II)) The title compound was synthesized by the following method according to the following reaction formula.

  20.0 g (0.062 mol) of bis- (p-biphenyl) amine, 52.8 g (0.186 mol) of 1-bromo-3-iodobenzene, and 25.8 g (0.186 mol) of anhydrous potassium carbonate Then, 6.0 g (0.094 mol) of copper powder and 40 mL of decahydronaphthalene were mixed and reacted at 180 to 200 ° C. for about 40 hours. Next, the reaction product was extracted with 600 mL of toluene, washed with water, and purified by column chromatography (carrier: silica gel, eluent: toluene / n-hexane = 1/2 (volume ratio)). Bis- (p-biphenyl) 12.7 g (43% yield) of 3-bromophenylamine (hereinafter referred to as compound (II-1)) was obtained.

  To a mixed solution of 12.0 g (0.026 mol) of the above compound (II-1) and 120 mL of tetrahydrofuran was added 18.2 mL (0.030 mol) of a 1.57 mol / L n-butyllithium-hexane solution. The mixture was reacted at -78 ° C for about 1 hour. Subsequently, 7.24 g (0.040 mol) of 2-isopropoxy-4,4,5,5-tetramethyl- [1,3,2] dioxaborolane was added and reacted for about 6 hours. The reaction product was extracted with 300 mL of toluene, washed with water, and purified by column chromatography (carrier: silica gel, eluent: toluene / n-hexane = 5/1 (volume ratio)). Bis- (p-biphenyl) -3- (4,4,5,5-tetramethyl- [1,3,2] dioxaborolanyl) phenylamine (hereinafter referred to as compound (II-2)) 4.76 g (yield 35%) )was gotten.

  2.3 g (0.0044 mol) of the above compound (II-2), 0.43 g (0.0018 mol) of m-dibromobenzene, and 0.12 g (0.00011) of tetrakis (triphenylphosphine) palladium (0). Mol), 40 mL of a 2M aqueous sodium carbonate solution, 20 mL of ethanol, and 80 mL of toluene were mixed and reacted at 80 to 90 ° C. for about 10 hours. Next, the reaction product was extracted with 400 mL of toluene, washed with water, and purified by column chromatography (carrier: silica gel, eluent: toluene / n-hexane = 3/1 (volume ratio)) to obtain compound (II). (Yield 67%) was obtained. This was purified by sublimation to obtain Compound (II) having a purity of 99.92% (purity confirmed by high performance liquid chromatography (HPLC)).

When the obtained compound was subjected to mass spectrometry, a peak was confirmed at m / e = 869 as shown in FIG. Moreover, when this compound was analyzed using the infrared absorption spectroscopy (IR) method, IR spectrum shown in FIG. 9 was obtained. Furthermore, Analysis of this compound ¹ H- using nuclear magnetic resonance ⁽¹ H-NMR) method, obtained NMR spectrum shown in FIG. ^10, 13 C-nuclear using magnetic resonance ⁽¹³ C-NMR) method As a result, the NMR spectrum shown in FIG. 11 was obtained. From these, it was confirmed that the compound obtained in Synthesis Example 2 was compound (II).

(Synthesis Example 3)
Synthesis of N, N, N ′, N′-tetrakis- (p-biphenyl)-[1,1 ′; 3 ′, 1 ″]-terphenyl-4,3 ″ -diamine (compound (III)) The title compound was synthesized by the following method according to the following reaction formula.

  3.5 g (0.0067 mol) of the above compound (I-2), 15.7 g (0.067 mol) of m-dibromobenzene, 0.23 g (0.00020) of tetrakis (triphenylphosphine) palladium (0). Mol), 40 mL of a 2M aqueous sodium carbonate solution, 20 mL of ethanol, and 80 mL of toluene were mixed and reacted at 80 to 90 ° C. for about 6 hours. Next, the reaction product was extracted with 300 mL of toluene, washed with water, and purified by column chromatography (carrier: silica gel, eluent: toluene / n-hexane = 1/1 (volume ratio)). -Biphenyl)-(3′-bromo-4,4′-biphenyl) amine (hereinafter referred to as compound (III-1)) 2.66 g (yield 72%) was obtained.

  1.40 g (0.0025 mol) of the above compound (III-1), 1.57 g (0.0030 mol) of the above compound (II-2), 0.087 g of tetrakis (triphenylphosphine) palladium (0) ( 0.000075 mol), 40 mL of a 2M aqueous sodium carbonate solution, 20 mL of ethanol, and 80 mL of toluene were mixed and reacted at 80 to 90 ° C. for about 10 hours. Next, the reaction product was extracted with 400 mL of toluene, washed with water, and purified by column chromatography (carrier: silica gel, eluent: toluene / n-hexane = 3/1 (volume ratio)) to obtain compound (III). 1.34 g (yield 62%) was obtained. This was further purified by sublimation to obtain compound (III) having a purity of 99.91% (purity confirmed by high performance liquid chromatography (HPLC)).

When the obtained compound was subjected to mass spectrometry, a peak was confirmed at m / e = 869 as shown in FIG. Moreover, when this compound was analyzed using the infrared absorption spectroscopy (IR) method, IR spectrum shown in FIG. 13 was obtained. Furthermore, Analysis of this compound ¹ H- with nuclear magnetic resonance ⁽¹ H-NMR) method, obtained NMR spectrum shown in FIG. ^14, 13 C-nuclear using magnetic resonance ⁽¹³ C-NMR) method As a result, the NMR spectrum shown in FIG. 15 was obtained. From these results, it was confirmed that the compound obtained in Synthesis Example 1 was compound (III).

(Synthesis Example 4)
Synthesis of N, N, N ′, N′-tetrakis- (p-biphenyl)-[1,1 ′; 4 ′, 1 ″]-terphenyl-3,3 ″ -diamine (compound (IV)) The title compound was synthesized by the following method according to the following reaction formula.

  1.70 g (0.0033 mol) of the above compound (II-2), 0.32 g (0.0014 mol) of p-dibromobenzene, 0.087 g (0.000075) of tetrakis (triphenylphosphine) palladium (0). Mol), 40 mL of a 2M aqueous sodium carbonate solution, 20 mL of ethanol, and 80 mL of toluene were mixed and reacted at 80 to 90 ° C. for about 10 hours. Next, the reaction product was extracted with 400 mL of toluene, washed with water, and purified by column chromatography (carrier: silica gel, eluent: toluene / n-hexane = 3/1 (volume ratio)) to obtain compound (IV). 0.61 g (52% yield) was obtained. This was further purified by sublimation to obtain Compound (IV) having a purity of 99.93% (purity confirmed by high performance liquid chromatography (HPLC)).

Example 1
First, ITO as a hole injection electrode (anode) was formed to a thickness of 200 nm on a prepared glass substrate and patterned. Next, the glass substrate was subjected to ultrasonic cleaning using a mixed solution of neutral detergent, acetone and ethanol. Subsequently, the glass substrate was pulled up from the mixed solution and dried, and then the substrate was subjected to ozone irradiation by performing infrared irradiation in a chamber substituted with oxygen to clean the substrate surface with ozone. And the glass substrate after washing | cleaning was fixed to the substrate holder of the vapor deposition apparatus (product made from ULVAC), and was pressure-reduced to 1 * 10 <^-4> Pa. Next, the compound (I) obtained in Synthesis Example 1 was deposited on the glass substrate to form a hole injection layer having a thickness of 100 nm.

  Subsequently, a compound represented by the following formula (11) was vapor-deposited on the hole injection layer while maintaining the system in a reduced pressure state to form a hole transport layer having a thickness of 30 nm. Next, while maintaining the reduced pressure inside the system, the compound represented by the following formula (12), the compound represented by the following formula (11), and the compound represented by the following formula (13) A first light emitting layer having a thickness of 20 nm was formed by co-evaporation on the hole transport layer at a ratio of 60: 38: 2.

  Next, the compound represented by the above formula (12) (anthracene derivative), the compound represented by the above formula (11), and the compound represented by the following formula (14), while maintaining the reduced pressure in the system Were vapor-deposited on the first light emitting layer at a mass ratio of 60: 38: 2 to form a second light emitting layer having a thickness of 20 nm.

  Furthermore, the compound represented by the following formula (15) was vapor-deposited on the second light emitting layer while maintaining the reduced pressure in the system, thereby forming an electron transport layer having a thickness of 20 nm. And the lithium fluoride as an electron injection layer was formed on the electron carrying layer by the vapor deposition method, maintaining the pressure-reduced state in the system. The thickness of this electron injection layer was 0.3 nm. And the aluminum as an electron injection electrode (cathode) was formed into a film with a film thickness of 150 nm on it, and the organic EL element of Example 1 was obtained.

(Example 2)
In the same manner as in Example 1 except that the hole injection layer was formed using Compound (II) obtained in Synthesis Example 2 instead of using Compound (I) obtained in Synthesis Example 1, the organic of Example 2 was used. An EL element was obtained.

(Example 3)
In the same manner as in Example 1 except that the hole injection layer was formed using the compound (III) obtained in Synthesis Example 3 instead of using the compound (I) obtained in Synthesis Example 1, the organic of Example 3 was used. An EL element was obtained.

Example 4
In the same manner as in Example 1 except that the hole injection layer was formed using the compound (IV) obtained in Synthesis Example 4 instead of using the compound (I) obtained in Synthesis Example 1, the organic of Example 4 was used. An EL element was obtained.

(Comparative Example 1)
Example 1 except that the hole injection layer was formed using a compound represented by the following formula (16) (hereinafter also referred to as compound (16)) instead of using the compound (I) obtained in Synthesis Example 1. In the same manner, an organic EL device of Comparative Example 1 was obtained.

(Comparative Example 2)
Example 1 except that the hole injection layer was formed using a compound represented by the following formula (17) (hereinafter also referred to as compound (17)) instead of using the compound (I) obtained in Synthesis Example 1. In the same manner, an organic EL device of Comparative Example 2 was obtained.

<Thermal characteristics of the compound used for the hole injection layer>
Table 76 shows the glass transition temperatures (Tg) and vapor deposition temperatures of the compounds (I) to (IV), (16) and (17) used in Examples 1 to 4 and Comparative Examples 1 and 2. The glass transition temperature was determined by differential scanning calorimetry.

<Element characteristic evaluation test>
About the organic EL elements of Examples 1 to 4 and Comparative Examples 1 and 2 obtained as described above, initial luminance and driving voltage at a constant current of 10 mA / cm ² in vacuum at room temperature, and The lifetime (luminance half-life) until the luminance was reduced by half when driven at a constant current of 50 mA / cm ² was measured. The results are shown in Table 77.

It is a schematic cross section which shows the organic EL element which concerns on 1st Embodiment of this invention. It is a schematic cross section which shows the organic EL element which concerns on 2nd Embodiment of this invention. It is a schematic cross section which shows the organic EL element which concerns on 3rd Embodiment of this invention. It is a mass spectrum of the compound for organic EL elements which concerns on the Example of this invention. It is IR spectrum of the compound for organic EL elements which concerns on the Example of this invention. It is a ^{1 H-NMR} spectrum of compound for organic EL device according to an embodiment of the present invention. It is a ¹³ C-NMR spectrum of the compound for organic EL devices according to the example of the present invention. It is a mass spectrum of the compound for organic EL elements which concerns on the Example of this invention. It is IR spectrum of the compound for organic EL elements which concerns on the Example of this invention. It is a ^{1 H-NMR} spectrum of compound for organic EL device according to an embodiment of the present invention. It is a ¹³ C-NMR spectrum of the compound for organic EL devices according to the example of the present invention. It is a mass spectrum of the compound for organic EL elements which concerns on the Example of this invention. It is IR spectrum of the compound for organic EL elements which concerns on the Example of this invention. It is a ^{1 H-NMR} spectrum of compound for organic EL device according to an embodiment of the present invention. It is a ¹³ C-NMR spectrum of the compound for organic EL devices according to the example of the present invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... 1st electrode, 2 ... 2nd electrode, 4 ... Substrate, 10 ... Light emitting layer, 11 ... Hole transport layer, 12 ... Electron transport layer, 13 ... Electron injection layer, 14 ... Hole injection layer, 100 ... 1st 1. Organic EL element according to one embodiment, 200... Organic EL element according to the second embodiment, 300... Organic EL element according to the third embodiment, P.

Claims (6)

The compound for organic EL elements represented by following General formula (1).

[In the formula (1), Ar represents a divalent group selected from the above general formula (A) , and R ¹ represents a phenyl group which may have a substituent. R ^{2 to} R ⁴ and R ^{5 to} R ⁸ are each independently an alkyl group having 1 to 4 carbon atoms, an N, N-dialkylamino group having 2 to 8 carbon atoms, or an optionally substituted phenyl. Indicates a group. n2 to n4 represent 0 or an integer of 1 to 5, and n5 to n8 represent 0 or an integer of 1 to 4. In formula (a), R ¹¹ and R ¹³ each independently represent an alkyl group having 1 to 3 carbon atoms, an N, N-dialkylamino group having 2 to 6 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms, m1 and m3 represent 0 or an integer of 1 to 4 . ]   The compound for organic EL elements of Claim 1 whose m1 and m3 are 0. The compound for organic EL elements of Claim 1 or 2 which has a total of 11-13 benzene rings. R ¹ is a phenyl group, N2 to N4 and n5~n8 is 0, compound for organic EL device of any one of claims 1-3. An organic EL device comprising one or more organic layers between two electrodes arranged opposite to each other,
At least 1 layer is an organic EL element containing the compound for organic EL elements of any one of Claims 1-4 among the said organic layers. The organic EL device according to claim 5, wherein the organic layer containing the compound for organic EL device is a hole injection layer.

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