JP4613505B2 - 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 for an organic EL display, for example, has a light emitting layer containing a light emitting organic compound such as a fluorescent organic compound or a phosphorescent organic compound sandwiched between a hole injection electrode (anode) and an electron injection electrode (cathode). It is an element that is excited and emits light by applying an electric field from the electrode to the light emitting organic compound. Such an organic EL element is superior in element characteristics such as luminance and light emission efficiency (quantum yield) as compared with an inorganic EL element, and is now in the stage of practical use.

  The light emission principle of this organic EL element is generally considered as follows. That is, first, holes (holes) injected from the hole injection electrode into the light emitting layer and electrons injected from the electron injection electrode into the light emitting layer recombine in the light emitting layer. Excitons are generated. Subsequently, when the exciton is deactivated, it is considered that energy is emitted by being released as a light (fluorescence, phosphorescence) component.

As a non-metallic luminescent organic compound used in an organic layer such as a light emitting layer or a carrier (electron, hole) transport layer of such an organic EL device, a polycyclic condensed aromatic compound such as an anthracene derivative or a naphthacene derivative is used. Are known. For example, in Patent Document 1, naphthacene or naphthacene is used for the purpose of providing an organic EL element excellent in durability in which light emission with sufficient luminance, particularly light emission at a long wavelength is obtained, and good light emission performance is sustained for a long period of time. An organic EL device having a light emitting layer containing the derivative has been proposed.
JP 2000-26334 A

  However, the present inventors have studied in detail the conventional organic EL elements including those described in Patent Document 1 described above. However, such conventional organic EL elements still have sufficient luminous efficiency. It has not been shown, and it has been found that further luminance improvement is necessary.

  Therefore, the present invention has been made in view of the above circumstances, and it is sufficient to use an organic EL element compound for forming an organic EL element exhibiting sufficiently excellent luminous efficiency, and the organic EL element compound. An object of the present invention is to provide an organic EL element capable of exhibiting excellent light emission luminance.

  As a result of intensive studies to achieve the above object, the present inventors have used a compound having a main skeleton in which the spread of π-conjugated electrons is larger in the organic layer of the organic EL device, the organic The inventors have found that the luminous efficiency of the EL element is improved, and have completed the present invention.

That is, the compound for organic EL devices of the present invention is represented by the following general formula (1).

Here, in the formula ^{(1), R 1, R} 2, R 3, R 4, R 5, R 6, R 7, R 8, R 9, R 10, R 11, R 21, R 22, R 23 , R ²⁴ , R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ and R ³¹ (hereinafter abbreviated as “R ^{1 to} R ¹¹ and R ^{21 to} R ³¹ ”), respectively, A hydrogen atom, an alkyl group which may have a substituent, an alkenyl group which may have a substituent, an aryl group which may have a substituent, or a monovalent which may have a substituent L represents a single bond, an arylene group which may have a substituent, a divalent heterocyclic group which may have a substituent, or a substituent. A linking group having a triarylamine structure is shown. In addition, at least two adjacent groups of R ^{1 to} R ¹¹ and R ^{21 to} R ³¹ may be bonded to each other or condensed to form a ring. The linking group having a triarylamine structure which may have a substituent is formed by elimination of two hydrogen atoms bonded to different aryl groups of the triarylamine which may have a substituent. And divalent linking groups.

  When the compound represented by the general formula (1) (hereinafter referred to as the compound (1)) is used in the organic layer of the organic EL device, the present inventors have currently investigated the factors that can achieve the object of the present invention. I think as follows. That is, since the compound (1) has a larger π-electron spread than the conventional light-emitting organic compound, it is estimated that electrons can move relatively freely on the molecule of the compound (1). The Therefore, in the organic layer containing the compound (1), carrier mobility is improved, and the recombination probability of carriers is considered to be sufficiently higher than that of the conventional one. As a result, it is estimated that the light emission efficiency (light emission luminance) of the organic EL element provided with such an organic layer is sufficiently high. However, the factor is not limited to this.

  In addition, the organic EL device using the compound (1) according to the present invention tends to have a longer driving life than the conventional one. This is considered to be because the emission efficiency is improved by increasing the molecular size and the deterioration of the organic material is suppressed by reducing the escape of electrons and holes, but the factor is not limited to this.

In the compound for an organic EL device of the present invention, R ^{1 to} R ¹¹ and R ^{21 to} R ³¹ may each independently have a hydrogen atom, an aryl group which may have a substituent, or a substituent. It is a good heterocyclic group, and L is preferably a phenylene group, a biphenylene group, a naphthalene group or a linking group represented by the following formula (2). By using such a compound, the light emission efficiency and driving life of the organic EL element tend to be further improved.

From the same viewpoint, R ^{1 to} R ¹¹ and R ^{21 to} R ³¹ are each independently an aryl group optionally having a hydrogen atom or a substituent, and L is a phenylene group, a biphenylene group, It is more preferable that it is a naphthalene group or a linking group represented by the above formula (2).

  In the organic EL device of the present invention, one or more organic layers among the one or two or more organic layers provided between the electrodes arranged to face each other and including the light emitting layer are represented by the general formula (1). It is characterized by containing a compound.

Here, in formula (1), R ^{1 to} R ¹¹ and R ^{21 to} R ³¹ may each independently have a hydrogen atom, an alkyl group that may have a substituent, or a substituent. An alkenyl group, an aryl group which may have a substituent, or a monovalent heterocyclic group which may have a substituent, L is a single bond, an arylene group which may have a substituent , A divalent heterocyclic group which may have a substituent or a linking group having a triarylamine structure which may have a substituent; At least two adjacent groups of R ^{1 to} R ¹¹ and R ^{21 to} R ³¹ may be bonded to each other or condensed to form a ring.

The organic EL device of the present invention usually has a green to orange emission waveform. Since the above-described compound (1) of the present invention is used in the organic layer, the luminous efficiency is sufficiently excellent, and the driving life and stability are further improved as compared with the conventional organic EL device. There is a tendency. Incidentally, when it is desired to change the emission waveform of the organic EL device may In other L-a ^R 1 ^{to R 11} and ^R 21 ^{to R 31} and the linking group is a substituent.

  In the organic EL device of the present invention, the light emitting layer preferably contains a compound represented by the general formula (1). In this organic EL device, since the compound (1) excellent in carrier mobility is used as a constituent material of the light emitting layer directly related to light emission, the light emission efficiency and the driving life tend to be further improved.

  The organic EL device of the present invention may include two or more light emitting layers, and one or more of the light emitting layers may contain the compound represented by the general formula (1). Since this organic EL device includes two or more light emitting layers, in addition to the above sufficiently excellent light emission efficiency and improved driving life, the adjustment of the light emission color tends to be easier, and variations in the light emission color are also possible. Tend to become more abundant.

  The organic EL device of the present invention includes one or more light emitting layers containing the compound represented by the general formula (1) and one or more light emitting layers not containing the compound, and does not contain the compound. Of the one or more light-emitting layers, one or more layers preferably contain a styrylamine derivative. Since the styrylamine derivative is a compound that exhibits very strong light emission and can contribute to the extension of the lifetime of the organic EL element, the organic EL element tends to further improve the light emission efficiency and the driving life. is there.

  In the organic EL device of the present invention, the light emitting layer preferably contains a compound represented by the above general formula (1) as a dopant material. Here, the “dopant material” refers to a light-emitting organic compound having a relatively high light emission ability and doped into the light-emitting layer. In addition, a “host material” described later is a light-emitting organic compound that has a light-emitting ability lower than that of a dopant material and excellent in film formability, and is a main component of a light-emitting layer. In the light emitting layer of the organic EL element, light is emitted mainly from the dopant material. Therefore, in the organic EL device of the present invention, when the compound (1) is used as this dopant material, the emission efficiency tends to be further improved.

  From the same viewpoint, in the organic EL device of the present invention, the light emitting layer may contain two or more dopant materials, and one or more of the dopant materials may be a compound represented by the general formula (1). preferable. In this case, when a luminescent organic compound other than the compound (1) is also used as the dopant material, the emission color can be adjusted. For example, when the compound (1) according to the present invention is used as a yellow light emitting material in the case of emitting two colors, or as a green material in the case of emitting three colors, it has a longer lifetime and higher life than the conventional one. There is a tendency that an organic EL element capable of efficient white light emission can be obtained.

  Furthermore, in this case, the light emitting layer containing the compound (1) as a dopant material is selected from the group consisting of an anthracene derivative as a host material, an aluminum complex having 8-quinolinol or a derivative thereof as a ligand, and a tetraarylbenzidine derivative. It is more preferable to further contain one or more kinds of compounds from the viewpoint of further improving the light emission efficiency and the driving life.

  The organic EL device of the present invention preferably emits white light. An organic EL element that emits white light is useful because its use is relatively abundant, such as easy adjustment of emission color when used in combination with a polarizing filter. In addition, for example, when the compound (1) according to the present invention is used as a yellow light emitting material in the case of emitting two colors, or as a green material in the case of emitting three colors, it has a longer life than the conventional one. In addition, it tends to be possible to obtain an organic EL element capable of highly efficient white light emission.

  Moreover, the organic EL device of the present invention preferably contains the compound represented by the general formula (1) as a host material. Thereby, it exists in the tendency which can improve luminous efficiency more compared with the conventional organic EL element which used the other compound as a host material. The host material plays a role of transporting carriers in the light emitting layer, and also has a role of recombining the carriers there to generate excitation energy. It is believed that the excitation energy generated on the host material molecules moves to the dopant material where it is emitted in the form of light. The compound (1) of the present invention is considered to have a carrier transport property smoother than that of the conventional compound and higher excitation energy generated by carrier recombination than that of the conventional compound. For these reasons, it is considered that when the compound (1) is used as a host material of the light emitting layer, the organic EL element tends to improve the light emission efficiency. However, the factor is not limited to this.

  In the organic EL device of the present invention, the organic layer provided between the electrode and the light emitting layer preferably contains the compound represented by the general formula (1). Examples of the organic layer include a hole injection layer, a hole transport layer, an electron injection layer, and an electron transport layer. Such an organic EL device of the present invention tends to exhibit better light emitting performance over a relatively long period of time. This is considered due to the fact that the compound (1) is excellent in carrier transportability.

  The organic EL device of the present invention can contain the compound represented by the general formula (1) in the organic layer so that the driving life thereof is improved. In this case, the compound (1) can also be used as an additive other than the host material, the dopant material, the main component of the carrier transport layer or the main component of the carrier injection layer.

  According to the present invention, an organic EL element compound for forming an organic EL element exhibiting sufficiently excellent luminous efficiency, and an organic EL capable of exhibiting sufficient emission luminance by using the compound for organic EL element. An element can be provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings as necessary. 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 for organic EL elements of this embodiment is a naphthacene dimer represented by the above general formula (1) or a derivative thereof (hereinafter referred to as “compound (1)”).

R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁸ , R ⁹ , R ¹⁰ and R ¹¹ (hereinafter abbreviated as “R ^{1 to} R ¹¹ ”), and R ²¹ , R ²² , R ²³ , R ²⁴ , R ²⁵ , R ²⁶ , R ²⁷ , R ²⁸ , R ²⁹ , R ³⁰ and R ³¹ (hereinafter abbreviated as “R ^{21 to} R ³¹ ”). The alkyl group which may have may be linear or branched. The number of carbon atoms of this alkyl group is preferably 1 to 5 from the viewpoint of further increasing the light emission efficiency of the organic EL device using this compound by improving the carrier transport property, and the ease of synthesis. Is more preferable. Examples of such an alkyl group include a methyl group, an ethyl group, and a propyl group, and among them, a methyl group is particularly preferable. The total number of alkyl groups in the whole molecule is preferably 0 to 4, more preferably 0 to 2.

The alkenyl group which may have a substituent as R ^{1 to} R ¹¹ and R ^{21 to} R ³¹ may be linear or branched, and the carbon number thereof is the above-mentioned alkyl. From the same viewpoint as the group, it is preferably 2 to 20, and more preferably 2 to 14. Such alkenyl groups include allyl groups such as vinyl and styryl groups. The total number of alkenyl groups is preferably 0 to 4 and more preferably 0 to 2 in the whole molecule.

The aryl group which may have a substituent as R ^{1 to} R ¹¹ and R ^{21 to} R ³¹ is, for example, a phenyl group, a naphthyl group (1-naphthyl group, 2-naphthyl group), a biphenylyl group (o- Examples include biphenylyl group, p-biphenylyl group, m-biphenylyl group) or tolyl group (o-tolyl group, m-tolyl group, p-tolyl group). Among these, a phenyl group, a naphthyl group, or a biphenylyl group is preferable from the same viewpoint as in the case of the alkyl group described above.

For R ^{1 to} R ¹¹ and R ^{21 to} R ³¹ , a heterocyclic group which may have a substituent may be employed. As such a heterocyclic group, an atom selected from the group consisting of N, O and S as a hetero element (more preferably an atom selected from the group consisting of N and S) from the same viewpoint as in the case of the alkyl group described above ) Is preferably a heterocyclic group (which may be monocyclic or condensed), a pyridyl group (2-pyridyl group, 3-pyridyl group, 4-pyridyl group), thiophenyl group (2 -Thiophenyl group, 3-thiophenyl group, 4-thiophenyl group), quinolyl group (2-quinolyl group, 3-quinolyl group, 4-quinolyl group, 8-quinolyl group, etc.) or benzothiazolyl group (5-benzothiazolyl group, 6- A benzothiazolyl group, a 7-benzothiazolyl group, an 8-benzothiazolyl group, and the like. In the present invention, the monovalent heterocyclic group which may have a substituent means a monovalent group derived from “a heterocyclic compound which may have a substituent”.

Moreover, as what is employ | adopted for R < ¹ > -R < ¹¹ > and R < ²¹ > -R < ³¹ >, even if it is a hydrogen atom other than the above-mentioned preferable substituent, it is preferable from viewpoints, such as improvement of luminous efficiency.

When at least two adjacent groups of R ^{1 to} R ¹¹ and R ^{21 to} R ³¹ are bonded to each other or condensed to form a ring, the formed condensed ring includes, for example, indene, naphthalene, anthracene, phenanthrene, quinoline , Iso-quinoline, quinoxaline, phenazine, acridine, indole, carbazole, phenoxazine, phenothiazine, benzothiazole, benzothiophene, benzofuran, acridone, benzimidazole, coumarin and flavone.

Since the characteristics as a luminescent material or carrier (electron, hole) transport material for organic EL elements are particularly excellent, the combination of R ^{1 to} R ¹¹ or the combination of R ^{21 to} R ^{31 in} the compound (1) is: The following (I-1) to (I-449), (II-1) to (II-2660), (IV-1 to IV-28), (II-2665) to (II-4456) and ( III-1) to (III-1792) are particularly preferred. In addition, it is preferable to combine any of the group of R ^{1 to} R ^{11 and} the group of R ^{21 to} R ³¹ . Here, A ^{1 to} A ¹⁶ represent the following substituents, and Ph represents a phenyl group.

  In the compound (1), the arylene group which may have a substituent used for L includes a phenylene group (1,2-phenylene group, 1,3-phenylene group, 1,4-phenylene group), methyl Phenylene group (2-methyl-1,4-phenylene group, 3-methyl-1,4-phenylene group, 3-methyl-1,2-phenylene group, 3-methyl-1,5-phenylene group, etc.), ethyl Phenylene group (2-ethyl-1,3-phenylene group, 2-ethyl-1,4-phenylene group, 3-ethyl-1,4-phenylene group, etc.), naphthylene group (1,4-naphthylene group, 1, 5-naphthylene group, 1,6-naphthylene group, 1,7-naphthylene group, 1,8-naphthylene group, 2,6-naphthylene group, etc.) or biphenylene group (4,4′-biphenylene group, 3,3 ′) -Biphenylene group, 2 2'biphenylene group and the like) and the like. Among them, a phenylene group, a naphthylene group, or a biphenylene group is preferable from the viewpoint of improving the recombination probability of carriers, improving the light emission efficiency of the organic EL element resulting therefrom, and ease of synthesis. .

  L may be a divalent heterocyclic group which may have a substituent. As such a divalent heterocyclic group, an atom selected from the group consisting of N, O and S as a hetero element (more preferably from the group consisting of N and S) from the same viewpoint as in the case of the alkyl group described above. A divalent heterocyclic group (which may be monocyclic or condensed ring) having at least one selected atom), each having a substituent, a pyridinylene group having the above formula ( More preferably, it is a group represented by 2), a dibenzothiophenylene group, an imidazole diyl group or a benzothiazole diyl group. In the present invention, the divalent heterocyclic group which may have a substituent means a divalent group derived from the “heterocyclic compound which may have a substituent”.

From the viewpoint of further improving the light emission efficiency of the organic EL device, L is a single bond or any one of the following (i-1) to (i-38) linking groups among those described above. More preferred.

  From the same point of view, L is a single bond of these, as well as formulas (i-1), (i-2), (i-3), (i-5), (i-7), (i- 8), (i-31), (i-35), and (i-38) are more preferably any linking group selected from the group consisting of groups represented by a single bond and formula (i- 1), (i-3), (i-5), (i-7) and (i-8) are particularly preferred.

  Since the compound (1) has a larger spread of π electrons compared to the conventional light-emitting organic compound, it is considered that electrons can move relatively freely on the molecule of the compound (1). Therefore, in the organic layer containing the compound (1), carrier mobility is improved, the carrier recombination probability is sufficiently higher than that of the conventional layer, and the luminance half-life is also improved. As a result, it is considered that the light emission efficiency (light emission luminance) of the organic EL element having such an organic layer is sufficiently high. Moreover, the organic EL element using the compound (1) tends to have a longer driving life than the conventional one. This is presumably because the influence of impurities on the molecule is reduced by increasing the molecular size of the luminescent organic compound.

The compound (1) of the present embodiment described above can be obtained from Journal of Organic Chemistry, Reynold C, Fusion et al., 1960, 25, 2226-2227, or Tetrahedron Lett., Jeffrey A. Dodge et al., 1988, vol. 29, no. 12, 1359 to 1362. For example, first, a compound (bromobenzofuran) represented by the following formula (a) and a compound represented by the following formula (b) are reacted in the presence of boron tribromide, and the following formula (c) 6-bromophenyl-11-phenyl-5,12-naphthacenequinone (hereinafter referred to as “quinone compound (c)”) is synthesized.

Next, the quinone compound (c) is reacted with phenyllithium represented by the following formula (d) to cause a nucleophilic attack of the phenyl group of the phenyllithium on the carbonyl carbon of the quinone compound (c). A diol body represented by the formula (e) (hereinafter referred to as “compound (e)”) is obtained.

Next, the rubrene (tetraphenylnaphthacene) derivative represented by the following formula (f) (hereinafter referred to as “compound (f)” is obtained by removing OH from the compound (e) in the presence of a reducing agent such as hydrogen iodide. ”).

Then, by coupling the compound (f) in the presence of bisdicyclooctadiene nickel (0) (Ni (cod) ₂ ), it is represented by the following formula (g) which is one kind of the compound (1). Naphthacene dimer derivative (hereinafter referred to as “compound (g)”).

Similarly, according to the following reaction schemes (h) and (j), compounds represented by the following formulas (k) and (p), which are one kind of the compound (1), are respectively synthesized.

When the compound (1) thus obtained is used for the light emitting layer, a green to orange light emission waveform is obtained. This emission waveform can be adjusted by replacing R ^{1 to} R ¹¹ and R ^{21 to} R ^{31 and} L described above.
(Organic EL device)

  Next, an organic EL element according to a preferred embodiment of the present invention will be described.

  FIG. 1 is a schematic cross-sectional view showing a first embodiment (single-layer organic EL) of an organic EL element according to the present invention. An organic EL element 100 shown in FIG. 1 has a structure in which a light emitting layer 10 is sandwiched between two electrodes (a first electrode 1 and a second electrode 2) arranged to face each other.

  FIG. 2 is a schematic cross-sectional view showing a second embodiment (two-layer organic EL) of an organic EL element according to the present invention. An organic EL element 200 shown in FIG. 2 has a structure in which a hole transport layer 11 is provided between the first electrode 1 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 (three-layer organic EL) of an organic EL element according to the present invention. The organic EL element 300 shown in FIG. 3 has a structure in which the electron transport layer 12 is provided between the second electrode 2 and the light emitting layer 10 of the organic EL element 200 in FIG.

FIG. 4 is a schematic cross-sectional view showing a fourth embodiment (four-layer organic EL) of an organic EL element according to the present invention. An organic EL element 400 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. 5 is a schematic cross-sectional view showing a fifth embodiment (five-layer type organic EL) of the organic EL element according to the present invention. An organic EL element 500 shown in FIG. 5 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 400 in FIG.

  Further, although not shown, a plurality of light emitting layers containing different constituent materials (type of material, content ratio of materials) may be provided as a light emitting layer.

  In the first to fifth embodiments, the first electrode 1 is formed on the substrate 4. In addition, the compound for an organic EL device of the present invention is contained as a constituent material in at least one of the light emitting layer, the hole transport layer, the hole injection layer, the electron transport layer, and the electron injection layer.

  In the said embodiment, the 1st electrode 1 and the 2nd electrode 2 function as a hole injection electrode (anode) and an electron injection electrode (cathode), respectively, and by application of the electric field by the power supply P, in 1st Embodiment Holes (holes) are injected from the first electrode 1 into the light emitting layer 10 (the hole transport layer 11 in the second to third embodiments, the hole injection layer 14 in the fourth to fifth embodiments), and the light emission is performed. Electrons are injected from the second electrode 2 into the layer 10 (the light emitting layer 10 in the second embodiment, the electron transport layer 12 in the third embodiment, and the electron injection layer 13 in the fourth to fifth embodiments), Based on these recombination, the compound for organic EL elements in the light emitting layer emits light.

  Moreover, the suitable thickness of a light emitting layer, an electron injection layer, an electron carrying layer, a hole injection layer, and a hole transport layer is all 5-100 nm.

(substrate)
Examples of the substrate 4 include amorphous substrates such as glass and quartz, crystal substrates such as Si, GaAs, ZnSe, ZnS, GaP, and InP, metal substrates such as Mo, Al, Pt, Ir, Au, Pd, and SUS, and polyolefins. A resin substrate such as polycarbonate 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, a metal compound, and the like. In order to efficiently and reliably inject electrons into the layer 10, it is preferable to use a material having a relatively low work function, and it 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 an 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.

(Light emitting layer)
For the light emitting layer 10, the above-mentioned compound for organic EL device (1) can be used as a constituent material. The organic EL device including such a light emitting layer 10 can withstand practical use, exhibits sufficiently high light emission efficiency and luminance, and can have a longer driving life than a conventional one. There is a tendency.

  The compound (1) of the present embodiment may be used alone as a constituent material of the light emitting layer 10, or may be used in the same amount in combination with other fluorescent (luminescent) constituent materials. Although it is good, it is preferable to use the compound (1) as a dopant material of the light emitting layer 10 and further contain a constituent material other than the compound (1) in the light emitting layer 10 as a host material. In this case, in the light emitting layer 10, the compound (1) is mainly the emission center, and the light emission by the compound 10 exhibits sufficient luminance due to the improvement of carrier recombination. Therefore, the organic EL element provided with such a light emitting layer 10 can have sufficiently excellent light emission efficiency.

  In this case, it is preferable to use a compound capable of emitting light as the host material, and more preferable to use an anthracene derivative, an aluminum complex having 8-quinolinol or a derivative thereof as a ligand, or tetraarylbenzene. . Thereby, the light emission wavelength characteristic of the host material can be changed, light emission shifted to a longer wavelength side can be achieved, and the light emission efficiency and / or stability of the organic EL element tends to be improved.

As a suitable anthracene derivative used for the host material of the light emitting layer 10, for example, a compound represented by the following general formula (a-1), (a-2) or (a-3), these compounds as units And a non-conjugated polymer obtained by pendating or crosslinking these compounds with an alkyl chain, an ether chain, or the like. Moreover, as a suitable polymer material, a polymer described in JP-A-2003-338375 can be used.

Here, in the above ^{formula, R 41 ~R 45, R 51} ~R 55, R 61 ~R 65 and ^R 71 ^{to R 75} is a hydrogen atom, an aryl group or heterocyclic group, each substituent They may be the same or different.

  Suitable aluminum complexes for use as the host material of the light-emitting layer 10 include JP-A 63-264692, JP-A-3-255190, JP-A-5-70733, JP-A-5-258859, and JP-A-6-26859. 215874 etc. can be mentioned.

  Specifically, first, tris (8-quinolinolato) aluminum, bis (8-quinolinolato) magnesium, bis (benzo {f} -8-quinolinolato) zinc, bis (2-methyl-8-quinolinolato) aluminum oxide, tris (8-quinolinolato) indium, tris (5-methyl-8-quinolinolato) aluminum, 8-quinolinolatolithium, tris (5-chloro-8-quinolinolato) gallium, bis (5-chloro-8-quinolinolato) calcium, 5,7-dichloro-8-quinolinolato aluminum, tris (5,7-dibromo-8-hydroxyquinolinolato) aluminum or poly [zinc (II) -bis (8-hydroxy-5-quinolinyl) methane] etc. Is mentioned.

  The aluminum complex may be an aluminum complex having another ligand in addition to 8-quinolinol or a derivative thereof. As such, bis (2-methyl-8-quinolinolato ) (Phenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (ortho-cresolato) aluminum (III), bis (2-methyl-8-quinolinolato) (meta-cresolato) aluminum (III), bis (2 -Methyl-8-quinolinolato) (para-cresolato) aluminum (III), bis (2-methyl-8-quinolinolato) (ortho-phenylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) ( (Meta-phenylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (para-phenylphenol) Lato) Aluminum (III), bis (2-methyl-8-quinolinolato) (2,3-dimethylphenolato) Aluminum (III), bis (2-methyl-8-quinolinolato) (2,6-dimethylphenolato) Aluminum (III), bis (2-methyl-8-quinolinolato) (3,4-dimethylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (3,5-dimethylphenolato) aluminum ( III), bis (2-methyl-8-quinolinolato) (3,5-di-tert-butylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (2,6-diphenylphenolato) Aluminum (III), bis (2-methyl-8-quinolinolato) (2,4,6-triphenylphenolato) Aluminum (III), bis (2-methyl-8-quinolinolato) 2,3,6-trimethylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (2,3,5,6-tetramethylphenolato) aluminum (III), bis (2-methyl-) 8-quinolinolato) (1-naphtholato) aluminum (III), bis (2-methyl-8-quinolinolato) (2-naphtholato) aluminum (III), bis (2,4-dimethyl-8-quinolinolato) (ortho-phenyl) Phenolato) aluminum (III), bis (2,4-dimethyl-8-quinolinolato) (para-phenylphenolato) aluminum (III), bis (2,4-dimethyl-8-quinolinolato) (meta-phenylphenolato) ) Aluminum (III), bis (2,4-dimethyl-8-quinolinolato) (3,5-dimethylphenolato) Aluminum (III), bis (2,4-di Til-8-quinolinolato) (3,5-di-tert-butylphenolato) aluminum (III), bis (2-methyl-4-ethyl-8-quinolinolato) (para-cresolato) aluminum (III), bis ( 2-methyl-4-methoxy-8-quinolinolato) (para-phenylphenolato) aluminum (III), bis (2-methyl-5-cyano-8-quinolinolato) (ortho-cresolato) aluminum (III), bis ( 2-methyl-6-trifluoromethyl-8-quinolinolato) (2-naphtholato) aluminum (III) and the like.

  In addition, bis (2-methyl-8-quinolinolato) aluminum (III) -μ-oxo-bis (2-methyl-8-quinolinolato) aluminum (III), bis (2,4-dimethyl-8-quinolinolato) aluminum (III) -μ-oxo-bis (2,4-dimethyl-8-quinolinolato) aluminum (III), bis (4-ethyl-2-methyl-8-quinolinolato) aluminum (III) -μ-oxo-bis ( 4-ethyl-2-methyl-8-quinolinolato) aluminum (III), bis (2-methyl-4-methoxyquinolinolato) aluminum (III) -μ-oxo-bis (2-methyl-4-methoxyquinolino) Lato) aluminum (III), bis (5-cyano-2-methyl-8-quinolinolato) aluminum (III) -μ-oxo-bis (5-cyano-2-methyl-8-quinolinolato) a Luminium (III), bis (2-methyl-5-trifluoromethyl-8-quinolinolato) aluminum (III) -μ-oxo-bis (2-methyl-5-trifluoromethyl-8-quinolinolato) aluminum (III) Etc.

  As a host material of the light emitting layer 10, in addition to the above-mentioned materials, a tetraarylethene derivative described in Japanese Patent Application No. 6-114456 or a triphenylamine derivative may be used.

  Moreover, when using a compound (1) as a dopant material, as a host material, it uses together 1 or more types of hole transportable compounds excellent in hole transportability, and 1 or more types of electron transport compounds excellent in electron transportability. It is preferable. As a result, a carrier hopping conduction path can be formed in the light emitting layer 10, so that each carrier moves in a polar dominant substance, carrier injection of the opposite polarity hardly occurs, and the organic compound is hardly damaged. The driving life tends to be extended. By including compound (1) as a dopant material in such a host material, the emission wavelength characteristic of the host material can be changed, the emission wavelength can be shifted to a longer wavelength, and the emission intensity. And the stability of the organic EL element tends to be improved.

  When using the compound (1) as a dopant material, the content ratio in the light emitting layer 10 is preferably 0.01 to 10% by mass with respect to the mass of all materials constituting the light emitting layer 10, and 0.1 to 0.1%. More preferably, it is 5 mass%. If the content ratio of the dopant material is below the lower limit value, the absolute amount of the dopant material contributing to light emission decreases, so that sufficient luminance tends not to be secured. If the upper limit value is exceeded, carrier hopping in the dopant material is likely to occur. Tends to occur and it becomes difficult to trap carriers in the dopant material, so that the probability of recombination of carriers decreases and the luminous efficiency tends to decrease.

  Furthermore, as a dopant material of the light emitting layer 10, in addition to the compound (1), a compound different from that can be used. Since the trapping property of carriers by the dopant material is different for each material, it tends to be able to trap carriers more efficiently in the light emitting layer 10 by appropriately selecting the dopant material. Therefore, by such selection, the recombination probability of carriers is further improved, and the light emission efficiency of the organic EL element including the light emitting layer 10 can be further increased.

  In view of the above, as a compound suitable for use as a dopant material in combination with the compound (1) of the present embodiment, for example, a compound as disclosed in JP-A 63-264692, more specifically, Includes at least one selected from compounds such as quinacridone and styryl dyes. Further, quinoline derivatives such as metal complex dyes having 8-quinolinol or a derivative thereof such as tris (8-quinolinolato) aluminum as a ligand, tetraphenylbutadiene, anthracene, perylene, coronene, 12-phthaloperinone derivatives, and the like can be given. Furthermore, a well-known phenylanthracene derivative, a well-known tetraarylethene derivative, etc. are mentioned.

  The compound (1) can also be used as a host material for the light emitting layer 10. Thereby, it exists in the tendency which can improve luminous efficiency more compared with the conventional organic EL element which used the other compound as a host material.

  In this case, the dopant material of the light emitting layer 10 is preferably a compound in which the energy gap of the dopant material is smaller than the energy gap of the compound (1) as the host material from the viewpoint of improving the light emission efficiency. As a compound used for such a dopant material, for example, a diindenoperylene derivative, a perylene derivative, a rubrene derivative, a pentacene derivative, a pyran derivative, and the like are preferable, and a diindenoperylene derivative is more preferable.

  Moreover, when using a compound (1) as a host material of the light emitting layer 10, the content rate in the light emitting layer 10 is 10-99.9 mass% with respect to the mass of all the materials which comprise the light emitting layer 10. Preferably, it is more preferable in it being 30-99.0 mass%. When the content of the host material is less than 10% by mass, carrier hopping in the dopant material is likely to occur, and it is difficult to trap carriers in the dopant material, so that the probability of carrier recombination decreases and the light emission efficiency is low. Tend to be. On the other hand, if the content ratio of the host material exceeds 99.9% by mass, the absolute amount of the dopant material contributing to light emission decreases, so that sufficient luminance cannot be ensured.

  Further, the compound (1) can be used not as a dopant material of the light emitting layer 10 but also as a host material, and as an additive for the purpose of improving the light emission efficiency, the driving life or the driving voltage. In this case, the content ratio of the compound (1) in the light emitting layer 10 is preferably about 0.1 to 10% by mass with respect to the mass of all materials constituting the light emitting layer 10. Thereby, compound (1) tends to be difficult to function as a host material. In addition, measurement of the emission spectrum of an organic EL element is mentioned as a confirmation method of whether the compound (1) is functioning as a dopant material. If the maximum peak of the emission spectrum is not recognized in the specific wavelength range indicated by the compound (1) by this measurement method, the probability that the compound (1) does not function as a dopant material is high.

  When the organic EL element compound (1) is not used as a constituent material of the light emitting layer 10, the constituent material of the light emitting layer is an exciton generated by recombination of electrons and holes, and the exciton releases energy. Any organic compound that emits light when returning to the ground state can be used without particular limitation.

  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, 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.

  In this case, it is preferable to use a combination of a host material and a dopant material as a constituent material of the light emitting layer 10. The emission wavelength characteristics can be changed by using a relatively strong dopant material, and the emission wavelength can be shifted to a longer wavelength, and the emission efficiency and / or stability of the organic EL element is improved. Tend to.

  As the host material, among the above-mentioned compounds, aromatic hydrocarbon compounds such as 1,10-phenanthroline derivatives, organometallic complex compounds, naphthalene, anthracene, naphthacene, perylene, benzofluoranthene or naphthofluoranthene, and their Derivatives, further styrylamine or tetraaryldiamine derivatives are preferred. As the dopant material, among the above-mentioned compounds, aromatic hydrocarbon compounds such as organometallic complex compounds, naphthalene, anthracene, naphthacene, perylene, benzofluoranthene, naphthofluoranthene, and derivatives thereof, further styrylamine or Tetraaryldiamine derivatives or quinacridone, coumarin, DCM and their derivatives are preferred.

  The light emitting layer may be a mixed layer of at least one kind of hole transporting compound and at least one kind of electron transporting compound, if necessary, and may contain a dopant in the mixed layer. In the mixed layer, a carrier hopping conduction path is generated, and each carrier moves in a polar dominant substance, so that it is considered that carrier injection in the reverse direction is unlikely to occur. This makes it difficult for the organic material constituting the light emitting layer to be damaged, and thus has the advantage of extending the drive life of the organic EL element.

  Examples of the hole transporting compound and electron transporting compound used in the mixed layer include 1,10-phenanthroline derivatives, organometallic complex compounds, aromatic hydrocarbon compounds such as anthracene, naphthacene, benzofluoranthene, naphthofluoranthene, and the like. It is preferable to use a derivative of As the hole transporting compound, it is also preferable to use an amine derivative having strong fluorescence. Examples of such an amine derivative include a triphenylamine derivative, a tetraarylbenzidine derivative, a styrylamine derivative, or an amine having an aromatic condensed ring. Derivatives.

  In this case, the preferred mixing ratio of the hole transporting compound and the electron transporting compound varies depending on the carrier mobility and the carrier concentration, but generally, the mixing ratio of the hole transporting compound and the electron transporting compound ( (Mass ratio) is preferably 1:99 to 99: 1, more preferably 10:90 to 90:10, and even more preferably about 20:80 to 80:20.

(Hall transport layer)
In the hole transport layer, the above-described compound (1) for an organic EL device of the present invention can be used as a constituent material. Since the organic EL element having such a hole transport layer tends to smoothly transport holes from the hole injection electrode (or hole injection layer) to the light emitting layer, further improvement in light emission efficiency and luminance tends to be recognized. is there. Moreover, the compound (1) which concerns on this invention, and the material which can be employ | adopted for the hole transport layer mentioned later other than that can also be used together for a hole transport layer. In this case, the content ratio of the compound (1) in the hole transport layer is preferably 10 to 99% by mass and more preferably 20 to 95% by mass with respect to the mass of all materials constituting the hole transport layer. preferable.

In addition to or in place of the compound for an organic EL device of the present invention, any hole transporting material of a low molecular weight material or a high molecular weight material can be used as a constituent material of the hole transporting layer. Examples of the hole transporting low molecular weight material include pyrazoline derivatives, arylamine derivatives, stilbene derivatives, triphenylamine derivatives, and tetraarylbenzidine derivatives. Also, hole transporting polymer materials include polyvinyl carbazole (PVK), polyethylene dioxythiophene (PEDOT), polyethylene dioxythiophene / polystyrene sulfonic acid copolymer (PEDOT / PSS), polyaniline / polystyrene sulfonic acid copolymer. (Pani / PSS). One of these hole transport materials may be used alone, or two or more thereof may be used in combination.

(Electron transport layer)
In the electron transport layer, the above-described compound (1) for an organic EL device of the present invention can be used as a constituent material. Since the organic EL device having such an electron transport layer tends to smoothly transport electrons from the electron injection electrode (or electron injection layer) to the light emitting layer, further improvement in light emission efficiency and luminance tends to be recognized. is there. Moreover, the compound (1) which concerns on this invention, and the material which can be employ | adopted for the other electron transport layer mentioned later can also be used together for an electron transport layer. In this case, the content ratio of the compound (1) in the electron transport layer is preferably 1 to 100% by mass and more preferably 5 to 99% by mass with respect to the mass of all materials constituting the electron transport layer. preferable.

  In addition to or in place of the compound for an organic EL device of the present invention, any electron transport material of a low molecular material or a polymer material can be used as a constituent material of the electron transport layer. Examples of the electron transporting low molecular weight material include anthracene derivatives, naphthalene derivatives, naphthacene derivatives, pyridine derivatives, quinoline derivatives, aluminum complexes, oxadiazole derivatives, anthraquinodimethane and derivatives thereof, benzoquinone and derivatives thereof, naphthoquinone and derivatives thereof. Derivatives, anthraquinones and derivatives thereof, tetracyanoanthraquinodimethane and derivatives thereof, 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.

  In particular, when the compound for an organic EL device of the present invention is used as a constituent material for an electron injection layer described later, the organic EL device is configured to form an electron transport material other than the compound for an organic EL device of the present invention. It is preferable to provide an electron transport layer used as a material. Such an organic EL element tends to further improve the lifetime.

  As the constituent material of the electron transport layer described above, one kind may be used alone, or two or more kinds may be used in combination.

(Hole injection layer)
In the hole injection layer, the above-described compound (1) for an organic EL device of the present invention can be used as a constituent material. An organic EL device having such a hole injection layer tends to allow holes to be injected relatively easily from the hole injection electrode, and thus further improvement in luminous efficiency and luminance tends to be observed. In addition, the compound (1) according to the present invention and other materials that can be used for the hole injection layer described later can be used in combination with the hole injection layer. In this case, the content ratio of the compound (1) in the hole injection layer is preferably 1 to 100% by mass and more preferably 5 to 99% by mass with respect to the mass of all materials constituting the hole injection layer. preferable.

  When the organic EL device compound of the present invention is not used as a constituent material of the hole injection layer, the material of the hole injection layer is not particularly limited as long as it is used for the hole injection layer of the conventional organic EL device. Alternatively, an organic compound material such as arylamine, phthalocyanine, polyaniline / organic acid, polythiophene / polymer acid, or a metal or metalloid oxide such as germanium or silicon can be used. These hole injecting materials may be used singly or in combination of two or more.

  Moreover, when providing both a hole transport layer and a hole injection layer, it is preferable to laminate | stack in order of the layer of a compound with a small ionization potential from the hole injection electrode side. Further, it is preferable to use a compound having a good thin film property on the surface of the hole injection electrode. By adopting such a stacking order, the driving voltage is lowered, and it tends to be possible to prevent the occurrence of current leakage and the generation / growth of dark spots. In addition, in the case of elementization, since vapor deposition is used, a thin film of about 1 to 10 nm can be made uniform and pinhole-free, so that the ion injection potential is small in the hole injection layer and the visible portion has absorption. Even if such a compound is used, it is possible to prevent a decrease in efficiency due to a change in color tone of light emission and reabsorption. The hole injecting and transporting layer can be formed by evaporating the above compound in the same manner as the light emitting layer and the like.

(Electron injection layer)
For the electron injection layer, the above-described compound (1) for an organic EL device of the present invention can be used as a constituent material. Since the organic EL device including such an electron injection layer tends to smoothly transport electrons from the electron injection electrode (or electron injection layer) to the light emitting layer, further improvement in light emission efficiency and luminance tends to be recognized. is there. Moreover, the compound (1) which concerns on this invention, and the material which can be employ | adopted for the other electron injection layer mentioned later can also be used together for an electron injection layer. In this case, the content ratio of the compound (1) in the electron injection layer is preferably 1 to 100% by mass and more preferably 5 to 99% by mass with respect to the mass of all materials constituting the electron injection layer. preferable.

  When the organic EL device compound of the present invention is not used as a constituent material of the electron injection layer or is used in combination, an alkali metal such as lithium, lithium fluoride, lithium oxide, or the like can be used for the electron injection layer.

  Moreover, when providing both an electron injection layer and an electron carrying layer, it is preferable to laminate | stack in order of the compound with a large value of an electron affinity from the electron injection electrode side.

  In addition, you may add the said compound for organic EL elements (1) in a trace amount to the hole transport layer, electron transport layer, hole injection layer, or electron injection layer mentioned above. In this case, the compound (1) supports such a function rather than functioning as each carrier transporting material or each carrier injecting material, thereby further extending the driving life of the organic EL element and increasing the luminous efficiency. A function that contributes to further improvement or further reduction of the driving voltage.

  The organic EL device according to the present invention can be produced by a known production method, and as a method for forming the organic layer, a vacuum vapor deposition method, an ionization vapor deposition method, a coating method, or the like is appropriately selected according to the material constituting the organic layer. Can be adopted.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  For example, in another embodiment of the organic EL device of the present invention, the organic layer may contain the compound (1) and further include two or more light-emitting layers having different host materials and / or dopant materials. Thereby, the adjustment of the emission color of the organic EL element tends to be further facilitated. As such an organic EL element, for example, two light emitting layers are provided, one of the light emitting layers contains the compound (1), and the other light emitting layer uses a material different from the compound (1). Can be mentioned. In this case, the material contained in the other light-emitting layer is not particularly limited as long as it is used in the light-emitting layer of the conventional organic EL device, but a styrylamine derivative is more preferable. This compound is a compound that exhibits very strong light emission and can contribute to the extension of the lifetime of the organic EL device. Therefore, the exemplified organic EL element tends to further improve both the light emission efficiency and the drive life.

  In addition, when two or more light emitting layers are provided, if a light emitting organic compound having a different light emission wavelength or light emission waveform is used for each light emitting layer, the organic EL device having such a light emitting layer emits white light. It is preferable from the viewpoint of showing. For example, when the compound (1) is used as the dopant material of one light emitting layer, white light emission with high color purity tends to be obtained when the above-described styrylamine derivative is used as the dopant material of the other light emitting layer.

  In order to obtain white light emission, even when the light emitting layer is a single layer, as a dopant material of the light emitting layer, compound (1) and a styrylamine derivative having a different emission wavelength or emission waveform from the compound (1) The luminescent organic compound may be used in combination.

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

(Synthesis Example 1)
<Synthesis of quinone compound>
First, 3 g (8.6 mmol) of bromoisobenzofuran represented by the above formula (a) synthesized in advance by a known method, 1.36 g (8.6 mmol) of naphthoquinone represented by the above formula (b), and Was dissolved in 20 cm ³ of dichloromethane in an ice bath to obtain a solution (A). Next, 8.6 cm ³ of a dichloromethane solution containing 1 mol / L boron tribromide was slowly added dropwise to the solution (A) to initiate the reaction. Subsequently, the solution obtained by dropping the dichloromethane was stirred for 3 hours to obtain a reaction solution (B).

Next, to obtain a solution (C) was added dichloromethane 100 cm ³ of distilled water 50 cm ³ in the reaction solution (B). Next, the solution (C) was transferred to a separatory funnel and subjected to separation washing three times using 100 cm ³ of distilled water. Thereafter, the obtained organic solvent phase was dried with magnesium sulfate, and the solvent was removed by an evaporator to obtain a solid.

Further, the solid was dissolved again in 20 cm ³ of dichloromethane, and subsequently purified using silica gel (C300, manufactured by Wako Pure Chemical Industries, Ltd., trade name, the same shall apply hereinafter) (silica gel chromatography). At this time, as the developing solvent, a mixture of toluene and n-hexane at 1: 1 (volume ratio) was used. After removing the solvent with an evaporator, the purified solid was reprecipitated in a mixed solvent of dichloromethane and n-hexane to obtain 3 g of a quinone compound (c) as a yellow powder (yield 71%).

<Synthesis of diol body>
3 g (6.1 mmol) of the quinone compound (c) was dissolved in 50 cm ³ of tetrahydrofuran (THF) in an Ar atmosphere to obtain a solution (D). Then, 3.2 cm ³ of phenyllithium in cyclohexane (1.9 mol / L) was dropped into the solution (D) under a temperature environment of −78 ° C. to obtain a reaction liquid (E).

After standing further reaction (E) for 10 hours to obtain a solution (F) was added to toluene 100 cm ³ of distilled water 50 cm ³ in the reaction solution (E). The solution (F) was transferred to a separatory funnel and subjected to separation washing three times using 100 cm ³ of distilled water. Thereafter, the obtained organic solvent phase was dried with magnesium sulfate, and the solvent was removed with an evaporator to obtain a solid.

Further, the solid was dissolved in 20 cm ³ of toluene and purified using silica gel (silica gel chromatography). At this time, as a developing solvent, a mixture of toluene and THF at 30: 1 (volume ratio) was used. After removing the solvent with an evaporator, the purified solid was reprecipitated in a mixed solvent of dichloromethane and n-hexane to obtain 2 g of a diol (compound (e)) as a white powder (yield 50). %).

<Synthesis of rubrene derivative>
2 g of the diol compound (e) was dissolved in 50 cm ³ of THF to obtain a solution (G). Next, 10 cm ³ of 57 volume% hydrogen iodide aqueous solution was slowly added to the solution (G) to obtain a reaction liquid (H).

After standing further reaction (H) for 2 hours to obtain a solution (J) of toluene was added to 100 cm ³ of distilled water 30 cm ³ in the reaction solution (H). Transfer solution (J) to a separatory funnel, performed three times was washed with distilled water of 100 cm ^3, after a further 3 times solution washed with 1 vol% thiosulfate aqueous sodium hydrogen 100 cm ^3, again Liquid separation washing was performed 3 times using 100 cm ³ of distilled water. Thereafter, the obtained organic solvent phase was dried with magnesium sulfate, and the solvent was removed with an evaporator to obtain a solid.

Next, the solid was dissolved in 20 cm ³ of toluene and purified using silica gel (silica gel chromatography). At this time, as a developing solvent, a mixture of toluene and n-hexane in a ratio of 1: 3 (volume ratio) was used. After removing the solvent with an evaporator, the purified solid was reprecipitated in a mixed solvent of dichloromethane and n-hexane to obtain 1.7 g of a rubrene derivative (compound (f)) as a red powder (yield). 70%).

<Synthesis of naphthacene dimer derivative>
1.7 g (2.8 mmol) of the above compound (f) was dissolved in 30 cm ³ of dimethylformamide in an Ar atmosphere to obtain a solution (K). Next, 0.46 g (1.7 mmol) of bisdicyclooctadiene nickel (0), 0.11 g (1.3 mmol) of bipyridine, and 1 mL of cyclooctadiene were added to the solution (K). (L) was obtained.

  Further, the reaction solution (L) was allowed to stand at 80 ° C. for 10 hours, and then 30 cm 3 of a 1N aqueous methanol solution was added to the reaction solution (L) and stirred for 2 hours. After stirring, extraction was performed using toluene, the extract was dried over magnesium sulfate, and the solvent was removed with an evaporator to obtain a solid.

Next, the solid was dissolved in 20 cm ³ of toluene and purified using silica gel (silica gel chromatography). At this time, as a developing solvent, a mixture of toluene and n-hexane in a ratio of 1: 5 (volume ratio) was used. Then, after removing the solvent with an evaporator, the purified solid was reprecipitated in a mixed solvent of dichloromethane and methanol to obtain 1 g of a red powder.

  When the obtained red powder was subjected to mass spectrometry, a main peak appeared in the vicinity of m / e = 1063 in the mass spectrum (see FIG. 6), and it was a compound (g) that is a naphthacene dimer derivative. It was confirmed (yield 70%).

Example 1
A glass substrate having an ITO transparent electrode (hole injection electrode) having a thickness of 100 nm was subjected to ultrasonic cleaning using a neutral detergent and pure water and dried. Next, the surface of the transparent electrode was washed with UV / O ₃ and then fixed to a substrate holder of a vacuum deposition apparatus (VPC-410, Vacuum Kiko Co., Ltd., trade name), and the pressure was reduced to 1 × 10 ⁻⁴ Pa or less. . Next, while maintaining the reduced pressure state, a compound represented by the following formula (4) was deposited to a thickness of 100 nm at a deposition rate of 0.2 nm / second to form a hole injection layer.

Subsequently, a compound represented by the following formula (5) (hereinafter referred to as “compound (5)”) was deposited to a thickness of 30 nm at a deposition rate of 0.2 nm / second to form a hole transport layer.

Furthermore, while maintaining the reduced pressure state, a compound represented by the following formula (6) as a host material (hereinafter referred to as compound (6)) and a compound (g) as a dopant material were converted into 98: 2 By mass ratio, it vapor-deposited in the thickness of 40 nm as the whole vapor deposition rate of 0.2 nm / sec, and was set as the light emitting layer.

  Next, while maintaining the reduced pressure state, the compound (6) was deposited to a thickness of 20 nm at a deposition rate of 0.2 nm / second to form an electron transport layer. Next, LiF was deposited to a thickness of 0.3 nm at a deposition rate of 0.01 nm / second to form an electron injection electrode, and Al was deposited to 150 nm as a protective electrode, whereby the four-layer organic EL device of Example 1 was obtained. Obtained.

When a direct current voltage was applied to the organic EL element of Example 1 and a current was passed, 1000 cd / m ² emission (emission maximum wavelength λ _max = 560 nm) was confirmed at a driving voltage of 6.5 V and 10 mA / cm ^2. The chromaticity coordinates were (x, y) = (0.48, 0.52). In addition, when a constant current of 50 mA / cm ² was passed through the device to continuously emit light, the initial luminance was 5000 cd / m ² and the luminance half time was 2500 hours. The emission spectrum of the organic EL device of Example 1 is shown in FIG.

(Example 2)
In forming the light emitting layer, the compound (6) as the host material and the compound (g) as the dopant material are deposited at a mass ratio of 98: 2 to a thickness of 40 nm, instead of being deposited as a dopant material. The same procedure as in Example 1 was performed except that the compound represented by the following formula (7) and the compound (g) as a host material were deposited in a mass ratio of 2:98 to a thickness of 50 nm. A four-layer organic EL device of Example 2 was obtained.

When a direct current voltage was applied to the organic EL element of Example 2 and a current was passed, 630 cd / m ² emission (emission maximum wavelength λ _max = 610 nm) was confirmed at a driving voltage of 6.5 V and 10 mA / cm ^2. The chromaticity coordinates were (x, y) = (0.65, 0.35). Further, when a constant current of 50 mA / cm ² was passed through the device to continuously emit light, the initial luminance was 3150 cd / m ² and the luminance half time was 4000 hours.

(Example 3)
Instead of vapor-depositing the compound (6) as the host material and the compound (g) as the dopant material (at a mass ratio of 98: 2 to a thickness of 40 nm) during the formation of the light emitting layer, A four-layer organic EL device of Example 3 was obtained in the same manner as Example 1 except for the above. That is, first, the compound (5) as the host material and the compound (g) as the dopant material were vapor-deposited at a mass ratio of 94: 6 to a thickness of 20 nm to obtain a first light emitting layer. Further, on the first light emitting layer, a compound represented by the following formula (8) as a host material (hereinafter referred to as “compound (8)”) and a formula (9) as a dopant material are represented. A compound (hereinafter referred to as “compound (9)”) was vapor-deposited at a mass ratio of 97: 3 to a thickness of 20 nm to obtain a second light emitting layer.

When a direct current voltage was applied to the organic EL element of Example 3 to pass a current, light emission of 900 cd / m ² (light emission maximum wavelength λ _max = 470 nm, 567 nm) was obtained at a driving voltage of 5.7 V and 10 mA / cm ^2. As confirmed, the chromaticity coordinates were (x, y) = (0.32, 0.33). Further, when a constant current of 50 mA / cm ² was passed through the device to continuously emit light, the initial luminance was 4500 cd / m ² and the luminance half time was 3000 hours.

Example 4
A 4-layer organic EL device of Example 4 was obtained in the same manner as Example 3 except that Compound (8) was used instead of Compound (5) when forming the first light emitting layer.

When a direct current voltage was applied to the organic EL element of Example 4 to pass a current, light emission of 1100 cd / m ² (light emission maximum wavelength λ _max = 471 nm, 566 nm) was obtained at a drive voltage of 6.0 V, 10 mA / cm ^2. The chromaticity coordinates were confirmed to be (x, y) = (0.31, 0.33). Further, when a constant current of 50 mA / cm ² was passed through the device to continuously emit light, the initial luminance was 5500 cd / m ² and the luminance half time was 3000 hours.

(Example 5)
When forming the light emitting layer, instead of depositing the compound (6) as the host material and the compound (g) as the dopant material at a mass ratio of 98: 2 to a thickness of 40 nm, as follows: A four-layer organic EL element of Example 5 was obtained in the same manner as Example 1 except that. That is, first, the compound (8) and the compound (5) (mass ratio 85:15) as the host material and the compound (g) as the dopant material are formed to a thickness of 20 nm at a mass ratio of 98: 2. The first light emitting layer was obtained by vapor deposition. Furthermore, the compound (8) and the compound (5) (mass ratio 85:15) as the host material and the compound (9) as the dopant material at a mass ratio of 96: 4 on the first light emitting layer, A second light emitting layer was obtained by vapor deposition to a thickness of 20 nm.

When a direct current voltage was applied to the organic EL element of Example 5 and a current was passed, emission of 1300 cd / m ² (light emission maximum wavelength λ _max = 470 nm, 565 nm) at a driving voltage of 5.6 V and 10 mA / cm ² was obtained. As confirmed, the chromaticity coordinates were (x, y) = (0.30, 0.34). Further, when a constant current of 50 mA / cm ² was passed through the device to continuously emit light, the initial luminance was 6500 cd / m ² and the luminance half time was 4000 hours. The emission spectrum of the organic EL element of Example 5 is shown in FIG.

(Comparative Examples 1-5)
4-layer organic EL devices of Comparative Examples 1 to 5 were obtained in the same manner as in Examples 1 to 5 except that the compound (rubrene) represented by the following formula (10) was used instead of the compound (g). It was.

When a direct current voltage was applied to the organic EL element of Comparative Example 1 and a current was passed, 600 cd / m ² emission (emission maximum wavelength λ _max = 558 nm) was confirmed at a driving voltage of 6.3 V and 10 mA / cm ² . The chromaticity coordinates were (x, y) = (0.47, 0.53). In addition, when a constant current of 50 mA / cm ² was passed through the device to continuously emit light, the initial luminance was 3000 cd / m ² and the luminance half time was 1300 hours.

When a direct current voltage was applied to the organic EL element of Comparative Example 2 to pass a current, light emission of 500 cd / m ² (light emission maximum wavelength λ _max = 610 nm) was confirmed at a driving voltage of 6.5 V, 10 mA / cm ² . The chromaticity coordinates were (x, y) = (0.65, 0.35). Further, when a constant current of 50 mA / cm ² was passed through the device to continuously emit light, the initial luminance was 2500 cd / m ² and the luminance half time was 1500 hours.

When a direct current voltage was applied to the organic EL element of Comparative Example 3 to cause a current to flow, emission of 700 cd / m ² at a driving voltage of 5.7 V, 10 mA / cm ² (emission maximum wavelength λ _max = 468 nm, 567 nm) was confirmed. The chromaticity coordinates were (x, y) = (0.32, 0.34). Further, when a constant current of 50 mA / cm ² was passed through the device to continuously emit light, the initial luminance was 3500 cd / m ² and the luminance half time was 1500 hours.

When a direct current voltage was applied to the organic EL element of Comparative Example 4 and a current was passed, emission of 750 cd / m ² (light emission maximum wavelength λ _max = 470 nm, 564 nm) was confirmed at a driving voltage of 5.9 V and 10 mA / cm ^2. The chromaticity coordinates were (x, y) = (0.31, 0.32). In addition, when a constant current of 50 mA / cm ² was passed through the device to continuously emit light, the initial luminance was 3750 cd / m ² and the luminance half time was 1500 hours.

When a direct current voltage was applied to the organic EL element of Comparative Example 5 and a current was passed, 800 cd / m ² emission (emission maximum wavelength λ _max = 470 nm, 565 nm) was confirmed at a driving voltage of 5.4 V and 10 mA / cm ^2. The chromaticity coordinates were (x, y) = (0.30, 0.34). In addition, when a constant current of 50 mA / cm ² was passed through the device to continuously emit light, the initial luminance was 4000 cd / m ² and the luminance half time was 1500 hours.

It is a schematic cross section which shows the organic EL element which concerns on 1st Embodiment. It is a schematic cross section which shows the organic EL element which concerns on 2nd Embodiment. It is a schematic cross section which shows the organic EL element which concerns on 3rd Embodiment. It is a schematic cross section which shows the organic EL element which concerns on 4th Embodiment. It is a schematic cross section which shows the organic EL element which concerns on 5th Embodiment. 2 is a mass spectrum of the compound obtained in Synthesis Example 1. FIG. 2 is an emission spectrum of the organic EL element of Example 1. 6 is an emission spectrum of the organic EL device of Example 5.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... 1st electrode, 2 ... 2nd electrode, 4 ... Substrate, 10 ... Light emitting layer, 11 ... Hole transport layer, 13 ... Electron injection layer, 14 ... Hole injection layer, 100 ... Organic according to the first embodiment EL element 200 ... Organic EL element according to the second embodiment 300 ... Organic EL element according to the third embodiment 400 ... Organic EL element according to the fourth embodiment 500 ... Organic EL element according to the fifth embodiment , P ... Power supply.

Claims (14)

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

(In the formula ^{(1), R 1, R} 2, R 3, R 4, R 7, R 8, R 9, R 10, R 21, R 22, R 23, R 24, R 27, R 28, R ²⁹ and R ³⁰ represent a hydrogen atom, and R ⁵ , R ⁶ , R ¹¹ , R ²⁵ , R ²⁶ and R ³¹ represent a hydrogen atom or an aryl group, provided that when R ⁵ is a hydrogen atom, R ⁶ and R ¹¹ Is an aryl group, and R ²⁶ and R ³¹ are aryl groups when R ²⁵ is a hydrogen atom , and L is a single bond, 1,4-phenylene group, biphenylene group, naphthylene group, or the following formula (2) A linking group represented by:

L is a biphenylene group, The compound for organic EL elements of Claim 1 characterized by the above-mentioned. An organic EL device compound represented by the following formula (g), (k), or (p):

Among one or two or more organic layers including a light emitting layer provided between electrodes arranged to face each other, one or more organic layers contain a compound represented by the following general formula (1). An organic EL device characterized by that.

(In the formula ^{(1), R 1, R} 2, R 3, R 4, R 7, R 8, R 9, R 10, R 21, R 22, R 23, R 24, R 27, R 28, R ²⁹ and R ³⁰ represent a hydrogen atom, and R ⁵ , R ⁶ , R ¹¹ , R ²⁵ , R ²⁶ and R ³¹ represent a hydrogen atom or an aryl group, provided that when R ⁵ is a hydrogen atom, R ⁶ and R ¹¹ Is an aryl group, and R ²⁶ and R ³¹ are aryl groups when R ²⁵ is a hydrogen atom , and L is a single bond, 1,4-phenylene group, biphenylene group, naphthylene group, or the following formula (2) A linking group represented by:

  The organic EL device according to claim 4, wherein the light emitting layer contains the compound.   The organic EL device according to claim 4, comprising two or more light emitting layers, wherein one or more of the light emitting layers contain the compound.   One or more light emitting layers containing the compound and one or more light emitting layers not containing the compound, wherein one or more of the light emitting layers not containing the compound is styryl. The organic EL device according to claim 4, comprising an amine derivative.   The organic light-emitting device according to claim 5, wherein the light emitting layer contains the compound as a dopant material.   9. The organic EL device according to claim 8, wherein the light emitting layer contains two or more dopant materials, and one or more of the dopant materials are the compounds.   The light emitting layer containing the compound further includes at least one compound selected from the group consisting of an anthracene derivative as a host material, an aluminum complex having 8-quinolinol or a derivative thereof as a ligand, and a tetraarylbenzidine derivative. The organic EL device according to claim 8, wherein the organic EL device is contained.   The organic EL element according to any one of claims 4 to 10, which emits white light.   The organic EL device according to claim 4, wherein the light emitting layer contains the compound as a host material.   The organic EL device according to claim 4, wherein an organic layer provided between the electrode and the light emitting layer contains the compound. The organic EL device according to claim 4, wherein the compound is contained in the organic layer so as to improve a driving life.

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