KR20110108574A - Benzo naphthacene derivatives and organic electroluminescent diode comprising the same - Google Patents

Abstract

The present invention relates to an aromatic derivative in the form of benzonaphthacene saturated with carbon 7 and an organic light emitting diode comprising the same. Preferably, the aromatic compound of the present invention can be applied to a blue or green organic light emitting diode, and the organic light emitting diode containing the same has a long life, high color purity, high luminous efficiency, and low voltage driving.

Description

Benzonaphthacene derivatives and organic light emitting diodes using the same {BENZO NAPHTHACENE DERIVATIVES AND ORGANIC ELECTROLUMINESCENT DIODE COMPRISING THE SAME}

The present invention relates to an aromatic derivative in the form of benzonaphthacene and an organic light emitting diode comprising the same.

The organic light emitting diode is a self-emitting type device, and when used as a flat panel display, its structure is simpler than other flat panel display devices, and thus, the manufacturing process is simple, high luminance and excellent viewing angle characteristics, fast response speed, and low driving voltage. As a result, the rate of adoption of electronic devices to which small display panels are applied is increasing. In addition, the power consumption is low as a device for lighting, high brightness and easy to implement the plane light, and its application as a light source for the back light of the display, lighting, billboards, etc. has become widespread. The organic electroluminescence phenomenon has been limited in practical terms since it was announced by Curnee in 1969 (US Pat. No. 3,172,862), but in 1987 by CW Tang of Eastman Kodak Corporation, the hole transport layer and electrons were formed between the electrode and the light emitting layer. The development of an organic light emitting diode that overcomes the disadvantages of light emission efficiency and lifespan with a stacked device with a transport layer has been reported (CW Tang, SA Vanslyke, Applied Physics Letters, Vol. 51, p. 913, 1987). Therefore, rapid development has been made since.

Since the development of CW Tang's stacked light emitting device, an optimal device structure has been developed.A general organic light emitting diode stack has a cathode (electron injection electrode) and an anode (hole injection electrode), and one or more organic layers between the two electrodes. It has a structure to include. In this case, the organic light emitting diode is an organic layer, in addition to the light emitting layer (EML), a hole injection layer (HIL), a hole transport layer (HTL), an electron transport layer (ETL, electron transport layer) or electron An electron injection layer (EIL) may be included, and an electron blocking layer (EBL) or a hole blocking layer (HBL) may be additionally added to trap the excitons in the light emitting layer and to trap the excitons in the light emitting layer. It may include. The organic light emitting diode including all of these organic layers has a structure laminated in the order of anode / hole injection layer / hole transport layer / electron blocking layer / light emitting layer / hole blocking layer / electron transport layer / electron injection layer / cathode.

When an electric field is applied to the organic light emitting diode of this structure, holes injected from the anode and electrons injected from the cathode recombine to form an exciton, an electron-hole pair, and the energy of the excitons is transferred to the light emitting material. Depending on the light emitted. The lifetime of stacked organic light emitting diodes is deeply related to the electrochemical and thin film stability of materials.

For example, when a light emitting material having poor thermal stability is used, the material is crystallized at a high temperature or a driving temperature, thereby shortening the life of the device. Anthracene derivatives have been used as typical organic electroluminescent device materials, including light emitting layers, hole transport layers and electron transport layers. For example, 9,10-di (naphthalen-2-yl) anthracene is used as a blue host material due to its excellent luminescence property, but has a disadvantage of shortening the life of the device because it is easily crystallized as the temperature of the device increases. In order to secure thermal stability, fluorene derivatives and benzofluorene derivatives in which carbons are linked to aromatic cyclic compounds have been developed, but because of their wide bandgap, they can be used as blue host materials for driving voltage and energy transfer to dopants. A problem occurred. In order to overcome these drawbacks, various types of materials have been developed, but until now, various technologies have been urgently developed because they do not sufficiently satisfy characteristics such as luminous efficiency, driving stability, and lifetime.

Accordingly, it is an object of the present invention to provide a 7H-benzo [de] naphthacene-based compound having excellent heat resistance and thin film stability and excellent lifespan, a method for preparing the same, and an organic light emitting diode including the same in an organic layer. will be.

In order to achieve the above object, the present invention provides a 7H-benzo [di] naphthacene derivative represented by the following formula (1).

Where

R ₁ and R ₂ are each independently hydrogen, deuterium, C _{1 -50} alkyl, C _{3 -50} cycloalkyl, C _{6 -50} aryl or a nuclear atoms of 5 to 50 heteroaryl group, wherein R ₁ and R ₂ is optionally C _{1 -50} alkyl, C _6-50 aryl, nuclear atoms may be substituted by from 5 to 50 heteroaryl or C _7-50 aralkyl, R ₁ and R ₂ are optionally bonded to each other C _{4- May form 50} saturated rings or unsaturated rings;

R ₃ and R ₄ are each independently hydrogen, deuterium, halogen, cyano, nitro, amino, thio, phosphoryl, phosphinyl, carbonyl, silyl, boranyl, C _1-50 alkyl, C _2-50 al Kenyl, C _2-50 alkynyl, C _1-50 alkoxy, C _3-50 cycloalkyl, C _6-50 aryl or heteroaryl having 5 to 50 nuclear atoms, wherein R ₃ and R ₄ are optionally C _{1 -6} unsubstituted or substituted by alkyl, amino, thio, phosphoryl, phosphine sulfinyl, carbonyl, silyl, borane yl, C _1-50 alkyl, C _2-50 alkenyl, C _2-50 alkynyl, C _{May be} substituted with _1-50 alkoxy, C _3-50 cycloalkyl, C _6-50 aryl, heteroaryl having 5 to 50 nuclear atoms or C _7-50 aralkyl, each of R ₃ and R ₄ is optionally substituted with an adjacent group Can be combined with each other to form a C _4-50 saturated ring or unsaturated ring;

n is an integer of 1-6.

The present invention also provides a method for preparing the compound of Formula 1.

Furthermore, the present invention provides an organic light emitting diode comprising the compound of Formula 1 in at least one organic layer.

The organic light emitting diode using the 7H-benzo [di] naphthacene derivative of the present invention has excellent heat resistance, high stability of the thin film constituting the device, long life, high color purity, high luminous efficiency, and low voltage driving. For this reason, the organic light emitting diode of the present invention can be used in various ways such as a flat panel display such as a wall-mounted TV, lighting or a backlight of the display.

The present invention uses a 7H-benzo [di] naphthacene derivative saturated with carbon at position 7 of benzo [di] naphthacene in consideration of driving stability, luminous efficiency, and color purity of blue or green light emission of an organic light emitting diode. It features.

In the present invention, in order to enhance the luminous efficiency of the blue and / or green organic light emitting diodes and to promote structural stability and to promote lifespan, two types of naphthalene are connected, that is, benzo [di] naphthacene represented by the following Chemical Formula 2 A benzonaphthacene aromatic ring compound having a form is used.

Specifically, the compound of the present invention is 7H-benzo [di] naphthacene, which is a saturated form of carbon 7 of benzo [di] naphthacene, is a basic light emitting unit, and various forms of R ₁ to R ₄ as in Chemical Formula 1 The invention has been completed in the form of a substituted functional group.

Through experiments and / or simulations, the benzo [di] naphthacene nucleus represented by the formula (2) shares a coplanar π orbital while two naphthyl groups form a six-membered ring, but the nucleus nucleus has a kind of substituent and / or Or, it was found that the π-orbitals on the same plane can be twisted according to the position, and thus the band gap can be finely adjusted. Particularly, when the carbon positions 1 and / or 13 of Chemical Formula 2 are substituted with a substituent other than hydrogen, the steric effect may be large, and thus, the π-orbital distortion may be largely induced on the same plane. At this time, the band gap difference between the alkyl group and the aryl group can be significantly different, and the steric effect is that the alkyl group is larger than the aryl group. On the other hand, the more aryl groups, the higher the luminescence efficiency of the parent nucleus, but the lower the band gap, the longer the wavelength shift.

Representative examples of the aromatic derivative represented by Formula 1 may be represented by the following Formula 1a or 1b:

[Formula 1a]

[Chemical Formula 1b]

Where

R ₁ to R ₄ are as defined above;

R ₅ to R ₆ are halogen, cyano, nitro, amino, thio, phosphoryl, phosphinyl, carbonyl, silyl, boranyl, C _1-50 alkyl, C _2-50 alkenyl, C _2-50 alky Nyl, C _1-50 alkoxy, C _3-50 cycloalkyl, C _6-50 aryl or heteroaryl having 5 to 50 nuclear atoms, wherein R ₃ and R ₄ are optionally substituted or substituted with C _1-6 alkyl Unsubstituted, amino, thio, phosphoryl, phosphinyl, carbonyl, silyl, boranyl, C _1-50 alkyl, C _2-50 alkenyl, C _2-50 alkynyl, C _1-50 alkoxy, C _{3 -50} cycloalkyl, C _6-50 aryl, 5 to 50 heteroaryl or C _7-50 aralkyl can be substituted,

n is an integer of 1-6, m is an integer of 0-5.

Synthesis of 7-benzo [di] naphthacene derivatives is carried out through a cyclization reaction using adjacent carbons of 1,2-binaphthyl derivatives in which carbon number 1 of first naphthalene and carbon number 2 of second naphthalene are continuously bonded. Are synthesized (see Schemes 1-4 below). However, when 1,2-binafphyl is combined, it is possible to generate isomers and it is necessary to control them.

As shown in Intermediate 1 of Scheme 1, -COOZ at position 1 of naphthalene 1 is reacted with RLi, which is a strong base, to produce intermediate 2 including tertiary alcohol. When the intermediate 2 is acid treated, a cyclization reaction occurs, whereby carbon b and carbon c of the second naphthalene can be combined with the first naphthalene. However, since most of the reaction results in the formation of more than 95% of isomer 1 by combining with carbon c, it is difficult to obtain the desired 7H-benzo [di] naphthacene in a commercially available yield.

Scheme 1

Therefore, in the present invention, as shown in Scheme 2, the R ' ₅ substituent is introduced at the carbon c position of the second naphthalene, thereby blocking the binding of the carbon c and the first naphthalene of the second naphthalene to the target 7H during the cyclization reaction. -Benzo [die] naphthacene was obtained.

Scheme 2

7H-benzo [di] naphthacene derivative can also be prepared by the method of Schemes 3 to 4 below. In Scheme 3, the second naphthalene-X ₂ functional group of intermediate 5 is treated with a strong base, and then reacted with a carbonyl compound to produce intermediate 6 including tertiary alcohol. Acid treatment of the resulting intermediate 6 causes a cyclization reaction with the first naphthalene, wherein carbon e and carbon f of the first naphthalene can be combined with the second naphthalene. However, as most of the reaction results in the formation of more than 90% of isomer 2 by combining with carbon f, it is difficult to obtain the desired 7H-benzo [di] naphthacene in a yield that can be used for commercial purposes.

Scheme 3

Therefore, in the present invention, as shown in Scheme 4, the R ' ₆ substituent is introduced to the carbon f position of the first naphthalene to block the binding of the carbon f and the second naphthalene of the first naphthalene to the target 7H during the cyclization reaction. -Benzo [die] naphthacene was obtained.

Scheme 4

In addition, the organic light emitting diode according to the present invention includes the compound of Formula 1 in at least one organic layer. At this time, the organic layer of the organic light emitting diode must include a light emitting layer, and may include a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer or a laminate thereof in addition to the light emitting layer, but if there is no defect of the device laminated structure There is no special limitation on the back.

Preferred multilayer organic light emitting diodes may be stacked in a multilayer structure of a substrate, an anode, a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer and a cathode from below.

The compound of Formula 1 may be applied to not only a light emitting layer but also a hole injection layer, a hole transport layer, an electron transport layer and the like depending on the type of the substituent to be introduced.

In the organic light emitting diode of the present invention, 7H-benzo [di] naphthacene derivative of Chemical Formula 1 may be preferably used in the light emitting layer. More preferably, the 7H-benzo [di] naphthacene derivative of Formula 1 may be used as the light emitting host material of the light emitting layer.

The light emitting layer of the organic electroluminescent diode of the present invention,

(i) injection function: the ability to inject holes from an anode or a hole injection layer when an electric field is applied, and to inject electrons from a cathode or an electron injection layer;

(Ii) transport function: transfer of injected charges (electrons and holes) to the force of an electric field; And / or

(Iii) Light emitting function: It has a function of providing a place of recombination of electrons and holes, and connecting it to light emission.

The compound of Formula 1 of the present invention may be used alone or in combination of two or more thereof in the light emitting layer, and when used as a light emitting host material, may be used together with other light emitting dopant materials known in the art. When using the compound of Formula 1 as a host material it may be added in an amount of 100 to 50% by weight relative to the light emitting layer.

Specific examples of the light emitting material (co-host material or dopant material) that can be used in the light emitting layer with the compound of Formula 1 include anthracene derivatives, naphthalene derivatives, phenanthrene derivatives, pyrene Derivatives, tetratracene derivatives, coronene derivatives, chrysene derivatives, fluoranthene derivatives, fluoranthene derivatives, perylene derivatives, phthaloperylene derivatives, benzonaphthacene (benzochrysene) derivatives, benzoanthracene derivatives, dibenzoanthracene derivatives, benzonaphthacene derivatives, stilbene derivatives, distyrylarylene derivatives, perinone derivatives, phthalo Phthaloperinone derivatives, naphthaloperinone derivatives, diphenylbutadiene derivatives, tetraphenylbutadiene derivatives aphenylbutadiene derivatives, coumarine derivatives, oxadiazole derivatives, bisbenzoxazoline derivatives, bisstyryl derivatives, pyrazine derivatives, cyclopentadiene derivatives , Quinoline metal complex derivatives, aminoquinoline metal complex derivatives, benzoquinoline metal complex derivatives, imine derivatives, diphenylethylene derivatives, vinyl anthracene derivatives, diamino Carbazole derivatives, pyrane derivatives, thiopyrane derivatives, quinacridone derivatives, rubrene derivatives, other fluorescent pigments, and mixtures thereof, but are not limited thereto. It doesn't happen.

In the case of the light emitting dopant material when the compound of Formula 1 is used alone or as a co-host of the light emitting layer, a material having a bandgap equal to or smaller than the bandgap of the host material with high efficiency of fluorescence or phosphorescence is preferable. Do.

The fluorescent dopant material is one selected from the above-mentioned light emitting materials according to the emission color required from amine compounds, aromatic compounds, metal complexes, cumin derivatives, tetraphenylbutadiene derivatives, bis styryl derivatives, and the like. In particular, aromatic amines, aromatic diamines and aromatic triamine derivatives are more preferable in terms of luminous efficiency. These dopant materials may be used alone or in combination of two or more.

The substrate used in the organic electroluminescent diode of the present invention is a light transmissive substrate, which is a substrate supporting the organic electroluminescent diode, preferably having a flat transmittance of 50% or more in the visible region having a wavelength of 400 to 700 nm. Glass plates, synthetic resin plates and the like are suitably used. As a glass plate, the plate shape | molded especially with soda-lime glass, barium strontium containing glass, lead glass, aluminosilicate glass, borosilicate glass, barium borosilicate glass, quartz, etc. are mentioned. Moreover, as a synthetic resin board, plates, such as a polycarbonate resin, an acrylic resin, a polyethylene terephthalate resin, a polyether sulfide resin, a polysulfone resin, are mentioned.

The anode used in the organic electroluminescent diode of the present invention is responsible for injecting holes into the hole injection and transport layer or the light emitting layer, and it is effective to have a work function of 4.5 eV or more. Specific examples of the positive electrode material used in the present invention include indium oxide (ITO), a mixture of indium oxide and zinc oxide (IZO), a mixture of ITO and cerium oxide (ITCO), a mixture of IZO and cerium oxide (IZCO), and oxidation A mixture of indium and cerium oxide (ICO), a mixture of zinc oxide and aluminum oxide (AZO), tin oxide (NESA), gold, silver, platinum, copper and the like may be applied.

The hole injection-transport layer used in the organic electroluminescent diode of the present invention is a layer for transporting the holes injected from the anode to the light emitting region, a material having a high hole mobility and an ionization energy of usually 5.5 eV or less, and a low electric field Materials that transport holes to the light emitting layer in terms of strength are preferred. The hole injection-transport layer material is not particularly limited in the case of a material having the above characteristics, and is conventionally used as a charge transport material for holes in a photoconductive material or a known one used for a hole injection layer of an organic electroluminescent diode. Although any of them can be selected and used, it is preferable to use an aromatic tertiary amine compound, and in particular, for example, 4,4′-bis having two condensed aromatic rings described in US Pat. No. 5,061,569. N- (1-naphthyl) -N-phenylamino) biphenyl (hereinafter abbreviated as NPD) and three triphenylamine units described in Japanese Patent Application Laid-Open No. 4-308688 are star bursts. And 4,4 ', 4'-tris (N- (3-methylphenyl) -N-phenylamino) triphenylamine (hereinafter abbreviated as MTDATA) connected in a form.

The electron injection layer-transport layer used in the organic electroluminescent diode of the present invention is a layer for transporting electrons from the cathode to the light emitting region, and is a layer made of a material having high electron mobility and good adhesion to the cathode. As a material used for an electron injection layer, the metal complex of 8-hydroxyquinoline derivative, an oxadiazole derivative, an imidazole derivative, and a pyridine derivative are suitable. As a specific example of the metal complex of the said 8-hydroxyquinoline derivative, tris (8-quinolinolato) aluminum which is an 8-hydroxyquinoline complex of aluminum can be used as an electron injection layer-transport layer material.

In the organic electroluminescent diode of the present invention, the electron injection layer composed of an insulator or a semiconductor between the cathode and the organic layer can prevent leakage of current to improve electron injection. Examples of such electron injection layer materials include alkali metal chalcogenides such as Li ₂ O, K ₂ O, Na ₂ S, Na ₂ Se, and Na ₂ O, CaO, BaO, SrO, BeO, BaS, and CaSe. to the alkaline earth metal chalcogenide, LiF, NaF, KF, CsF , LiCl, KCl , and halides of alkaline earth metal of an alkali metal, such as halides and _{CaF 2, BaF 2, SrF 2} , MgF 2 and BeF ₂ of such as NaCl It is preferable to use at least one metal compound selected from the group consisting of.

As the cathode used in the organic electroluminescent diode of the present invention, a metal having a work function of 4 eV or less, an alloy, an electrically conductive compound, and a mixture thereof as an electrode material is used. Specific examples of such electrode materials include sodium, sodium-potassium alloys, magnesium, lithium, cesium, magnesium-silver alloys, aluminum / aluminum oxide, Al / LiO, Al / LiO, Al / LiF, aluminum-lithium alloys, indium, rare earths. A metal etc. can be mentioned, It can manufacture by forming a thin film by methods, such as vapor deposition and sputtering.

Each layer constituting the organic light emitting diode may be formed by applying any conventional method such as dry deposition such as vacuum deposition, sputtering, plasma, or ion plating, or wet deposition such as radiation coating, immersion coating, and flow coating. Can be. The film thickness is not particularly limited, but if the film thickness is too thick, a high applied voltage is required to obtain a constant light output, resulting in poor efficiency. If the film thickness is too thin, a pin hole or the like is generated to apply an electric field. Also, sufficient light emission luminance cannot be obtained. Typical film thickness is preferably in the range of 5 nm to 10 μm, but more preferably in the range of 10 nm to 0.2 μm.

Hereinafter, the present invention will be described in more detail based on the following Examples and Comparative Examples. However, the following examples are not intended to limit the invention only.

≪ Examples and Comparative Examples &

Claims (5)

7H-benzo [di] naphthacene derivative represented by the following formula (1):
[Formula 1]

Where
R ₁ and R ₂ are each independently hydrogen, deuterium, C _1-50 alkyl, C _3-50 cycloalkyl, C _6-50 aryl or heteroaryl having 5 to 50 nuclear atoms, wherein R ₁ and R ₂ are optionally C _1-50 alkyl, C _6-50 aryl, nuclear atoms may be substituted by from 5 to 50 heteroaryl or C _7-50 aralkyl, R ₁ and R ₂ are optionally bonded to each other C _{4- May form 50} saturated rings or unsaturated rings;
R ₃ and R ₄ are each independently hydrogen, deuterium, halogen, cyano, nitro, amino, thio, phosphoryl, phosphinyl, carbonyl, silyl, boranyl, C _1-50 alkyl, C _2-50 al Kenyl, C _2-50 alkynyl, C _1-50 alkoxy, C _3-50 cycloalkyl, C _6-50 aryl or heteroaryl having 5 to 50 nuclear atoms, wherein R ₃ and R ₄ are optionally C _{1 -6} unsubstituted or substituted by alkyl, amino, thio, phosphoryl, phosphine sulfinyl, carbonyl, silyl, borane yl, C _1-50 alkyl, C _2-50 alkenyl, C _2-50 alkynyl, C _{May be} substituted with _1-50 alkoxy, C _3-50 cycloalkyl, C _6-50 aryl, heteroaryl having 5 to 50 nuclear atoms or C _7-50 aralkyl, each of R ₃ and R ₄ is optionally substituted with an adjacent group Can be combined with each other to form a C _4-50 saturated ring or unsaturated ring;
n is an integer of 1-6. The 7H-benzo [di] naphthacene derivative according to claim 1, wherein Formula 1 is 1a or 1b.
[Formula 1a]

[Chemical Formula 1b]

Where
R ₁ to R ₄ are the same as defined in Formula 1;
R ₅ and R ₆ are halogen, cyano, nitro, amino, thio, phosphoryl, phosphinyl, carbonyl, silyl, boranyl, C _1-50 alkyl, C _2-50 alkenyl, C _2-50 alky Nyl, C _1-50 alkoxy, C _3-50 cycloalkyl, C _6-50 aryl or heteroaryl having 5 to 50 nuclear atoms, wherein R ₃ and R ₄ are optionally substituted or substituted with C _1-6 alkyl Unsubstituted, amino, thio, phosphoryl, phosphinyl, carbonyl, silyl, boranyl, C _1-50 alkyl, C _2-50 alkenyl, C _2-50 alkynyl, C _1-50 alkoxy, C _{3 -50} cycloalkyl, C _6-50 aryl, 5 to 50 heteroaryl or C _7-50 aralkyl can be substituted,
n is an integer of 1-6, m is an integer of 0-5. The 7H-benzo [di] naphthacene derivative according to claim 2, wherein R ₅ and R ₆ are substituted or unsubstituted alkyl or aryl groups. An organic light emitting diode comprising the compound according to any one of claims 1 to 3 in at least one organic layer. The method for producing the compound according to any one of claims 1 to 3 according to any one of the following Schemes 1 to 4.
[Reaction Scheme 1]

Scheme 2

[Reaction Scheme 3]

[Reaction Scheme 4]