JP2010138090A - New pyrene compound - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new pyrene compound having a high thermal stability. <P>SOLUTION: This new pyrene compound is expressed by general formula (1) [wherein, FL is fluorenyl; A1 is a benzene ring, naphthalene ring or fluorene ring; A2 is aryl; and these may have substituents]. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a novel pyrene compound and an organic EL device having the same in an organic compound layer.

Many compounds having pyrene as a skeleton have been synthesized as organic EL materials, and a pyrene compound has been disclosed as a material excellent in device durability (Patent Document 1). However, since higher element durability is required for practical use, there is an urgent need to develop a material with higher stability.
WO2005 / 123634

  An object of the present invention is to provide a novel pyrene compound having high thermal stability. Another object of the present invention is to provide a highly durable organic EL device by using this new pyrene compound having high thermal stability.

  Therefore, this invention provides the pyrene compound represented by General formula (1).

In the formula, FL represents a substituted or unsubstituted fluorenyl group.
A1 represents a substituted or unsubstituted benzene ring, a substituted or unsubstituted naphthalene ring, or a substituted or unsubstituted fluorene ring.
A2 represents a substituted or unsubstituted aryl group.

Further, the present invention provides an organic EL device having an anode, a cathode, and an organic compound layer disposed between the anode and the cathode, wherein the organic compound layer has the pyrene compound described above. An element is provided.

  According to the present invention, a novel pyrene compound having high thermal stability can be provided. Moreover, a highly durable organic EL element can be provided by using this new pyrene compound with high thermal stability.

The pyrene compound according to the present invention is a compound represented by the general formula (1).
The compound has an aryl group at the 1-position of the pyrene ring and a fluorenyl group at the 7-position of the pyrene ring.

  By introducing a fluorenyl group at the 7-position of the pyrene ring, stacking of pyrenes is inhibited by steric hindrance, resulting in a highly amorphous compound, high thermal stability, and a long-life device can be obtained.

  Further, the 7-position of the pyrene ring is electronically specific, and even when a fluorenyl group is introduced, the emission wavelength is hardly increased. Therefore, introducing a fluorenyl group at the 7-position of the pyrene ring is an effective means for organic EL materials such as blue and green having a short emission wavelength.

In the formula, the fluorenyl group represented by FL may be unsubstituted or may have a substituent. Specifically,
Methyl group, ethyl group, isopropyl group, n-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, octadecyl group, etc. A chain alkyl group,
A cyclic alkyl group such as a cyclopentyl group and a cyclohexyl group,
Examples thereof include aryl groups such as phenyl group, tolyl group, biphenyl group, naphthyl group, and fluorenyl group.

  Moreover, these substituents may be further substituted with the above substituents.

  In the general formula (1), A1 greatly affects the HOMO of the molecule. If the conjugation is made too long, the stability against oxidation becomes low, and the emission wavelength also becomes longer.

  Therefore, A1 is preferably a benzene ring, naphthalene ring or fluorene ring having a short conjugate length when this compound is used as a light emitting material such as blue or green having a short emission wavelength. In this case, it is particularly preferred when used as a host material.

  The organic EL element has at least an anode, a cathode, and an organic compound layer disposed between them. That the organic EL element emits light means that light is emitted from this organic compound layer. Such an organic compound that emits light is referred to herein as a light-emitting material. An organic compound layer having a light emitting material is a light emitting layer.

  The organic compound layer may be composed of a host material and a guest material. The host material is a main component constituting the organic light emitting layer. The guest material is a minor component.

  In the general formula (1), these benzene ring, naphthalene ring or fluorene ring represented by A1 may be unsubstituted or may have a substituent.

Specific examples of the substituent include methyl group, ethyl group, isopropyl group, n-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group. Chain alkyl groups such as hexadecyl group and octadecyl group,
A cyclic alkyl group such as a cyclopentyl group and a cyclohexyl group,
Examples thereof include aryl groups such as phenyl group, tolyl group, biphenyl group, naphthyl group, and fluorenyl group.

  Moreover, these substituents may be further substituted, and in that case, may have the above-mentioned substituents.

  In general formula (1), the aryl group represented by A2 can be selected according to the required emission wavelength. The aryl group represented by A2 is particularly preferably an aryl group having 1 to 3 rings.

  When the aryl group represented by A2 is an aryl group having 1 to 3 rings, such a compound is suitable for a light-emitting material such as blue or green having a short emission wavelength, and particularly suitable as a host material.

  Examples of the aryl group having 1 to 3 rings include a phenyl group, a biphenyl group, a naphthyl group, a fluorenyl group, a phenanthryl group, and an anthryl group (anthryl group). The biphenyl group, naphthyl group, and fluorenyl group are assumed to be a bicyclic aryl group. The phenanthryl group and the anthryl group (anthryl group) are tricyclic aryl groups. Among these, naphthyl group, fluorenyl group, and phenanthryl group are more preferable. When the aryl group represented by A2 is any of these, the film property is good.

A2 may be unsubstituted or may have a substituent. In particular,
Methyl group, ethyl group, isopropyl group, n-butyl group, tert-butyl group, pentyl group, hexyl group, octyl group, decyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, hexadecyl group, octadecyl group, etc. A chain alkyl group,
A cyclic alkyl group such as a cyclopentyl group and a cyclohexyl group,
Examples thereof include aryl groups such as phenyl group, tolyl group, biphenyl group, naphthyl group, and fluorenyl group.

  Moreover, these substituents may be further substituted, and in that case, may have the above-mentioned substituents.

  Specific examples of the pyrene compound according to the present invention are shown below by structural formulas, but the present invention is not limited to these.

  Since all of these exemplified compounds have a fluorenyl group introduced at the 7-position of the pyrene ring, stacking between pyrenes is inhibited by steric hindrance, resulting in a highly amorphous compound, high thermal stability, and a long-life device. be able to.

  Although there is no restriction | limiting in particular in the manufacturing method of the novel pyrene compound shown by General formula (1), For example, according to the method shown below, it can manufacture.

  First, an example of the synthesis of intermediate A is shown.

  Next, an example of the synthesis of intermediate B is shown.

  Next, an example of synthesizing a novel pyrene compound from these intermediate A and intermediate B will be shown.

  Next, the organic EL element provided with the pyrene compound of the present invention will be described in detail.

  As described above, the organic EL element according to the present embodiment is composed of at least a pair of electrodes including an anode and a cathode and an organic compound layer sandwiched between the pair of electrodes. In addition to the organic compound layer, another compound layer (either an inorganic compound layer or another organic compound layer) may be further provided between the electrodes.

  The organic compound layer has the pyrene compound represented by the formula (1). 1 to 5 show preferred examples of organic EL elements.

  First, reference numerals of the drawings will be described.

  1 is a substrate, 2 is an anode, 3 is a light emitting layer, 4 is a cathode, 5 is a hole transport layer, 6 is an electron transport layer, 7 is a hole injection layer, and 8 is a hole / exciton blocking layer.

  FIG. 1 is a cross-sectional view showing an example of an organic EL element according to this embodiment. FIG. 1 shows a structure in which an anode 2, a light emitting layer 3 and a cathode 4 are sequentially provided on a substrate 1. The organic EL device used here is useful when it has a single hole transport ability, electron transport ability, and light emitting performance by itself or when a compound having each characteristic is used in combination. .

  FIG. 2 is a cross-sectional view showing another example of the organic EL element according to this embodiment. FIG. 2 shows a configuration in which an anode 2, a hole transport layer 5, an electron transport layer 6 and a cathode 4 are sequentially provided on a substrate 1. In this case, the light emitting material is either a hole transporting property or an electron transporting property, or a material having both functions is used for each layer, and it is combined with a simple hole transporting material or an electron transporting material that does not emit light This is useful when used. In this case, the light emitting layer 3 is composed of either the hole transport layer 5 or the electron transport layer 6.

  FIG. 3 is a cross-sectional view showing another example of the organic EL element according to this embodiment. FIG. 3 shows a structure in which an anode 2, a hole transport layer 5, a light emitting layer 3, an electron transport layer 6 and a cathode 4 are sequentially provided on a substrate 1. This separates the functions of carrier transport and light emission. It is used in a timely combination with compounds having hole transporting properties, electron transporting properties, and luminescent properties, which greatly increases the degree of freedom of material selection and allows the use of various compounds with different emission wavelengths. Diversification of hue becomes possible. Further, it is possible to effectively confine each carrier or exciton in the central light emitting layer 3 to improve the light emission efficiency.

  FIG. 4 is a cross-sectional view showing another example of the organic EL element according to this embodiment. FIG. 4 shows a configuration in which a hole injection layer 7 is inserted on the anode 2 side with respect to FIG. 3, and is effective in improving the adhesion between the anode 2 and the hole transport layer 5 or improving the hole injection property. It is effective.

  FIG. 5 is a cross-sectional view showing another example of the organic EL element according to this embodiment. FIG. 5 shows a configuration in which a layer (hole / exciton blocking layer 8) that prevents holes or excitons (excitons) from passing to the cathode 4 side is inserted between the light emitting layer 3 and the electron transport layer 6. It is. By using a compound having a very high ionization potential as the hole / exciton blocking layer 8, the structure is effective in improving the light emission efficiency.

  However, FIGS. 1 to 5 are very basic element configurations, and the configuration of the organic EL element using the pyrene compound of the present invention is not limited to these. For example, various layer configurations such as providing an insulating layer at the interface between the electrode and the organic layer, providing an adhesive layer or interference layer, and the hole transporting layer are composed of two layers having different ionization potentials can be employed.

  The compound represented by the general formula (1) used in the present invention can be used in any form shown in FIGS.

  In particular, an organic layer using the compound of the present invention is excellent in stability over time because a layer formed by a vacuum deposition method or a solution coating method hardly causes crystallization.

  In the organic EL device according to the present embodiment, the compound represented by the general formula (1) is used as a constituent component of the light-emitting layer, but known low-molecular and polymer-based hole transport compounds, light-emitting compounds, or electron transports are used as appropriate. Compounds and the like can also be used together.

  The substrate on which the organic EL element according to the present embodiment is arranged is not particularly limited, but an opaque substrate such as a metal substrate or a ceramic substrate, or a transparent substrate such as glass, quartz, or a plastic sheet is used. It is done.

  It is also possible to control the color light by using a color filter film, a fluorescent color conversion filter film, a dielectric reflection film, or the like on the substrate. It is also possible to create a thin film transistor (TFT) on a substrate and connect it to create an element.

  Further, regarding the light extraction direction of the element, either a bottom emission configuration (configuration in which light is extracted from the substrate side) or a top emission (configuration in which light is extracted from the opposite side of the substrate) is possible.

  The anode and the cathode may be formed of a preferable material as appropriate. The electrode arranged on the side where light is extracted from the element is semi-transmissive or transmissive to the light. For example, ITO is a preferred material.

  Further, when it is necessary to reflect light within the element, a highly reflective material is preferably used. For example, silver or aluminum.

  Further, even if it is necessary to reflect light in the element, an electrode made of a semi-transmissive or transmissive material may be provided on the reflection side, and a reflection member may be separately provided.

  The organic EL element may be driven by a so-called active matrix driving method or may be driven by a simple matrix driving method. In the case of the active matrix driving method, the driving circuit for driving the organic EL element is composed of a TFT, a capacitor and the like.

  A plurality of organic EL elements can be used as light emitting points. For example, it can be used as a lighting fixture. In addition, a light emitting point can be used as a pixel for a display portion of a display device. Such a display device can be used for a PC display, a television, and an imaging device.

  The imaging device is a digital video camera, a digital still camera, or the like, and the imaging device has an image display unit called a viewfinder. A display unit having an organic EL element can be used as the image display unit.

  In addition, a display unit having an organic EL element is used for an operation panel unit of various electric devices.

  In addition, an organic EL element can be used as a light source for exposing a photosensitive member in an electrophotographic image forming apparatus such as a laser printer or a copying machine. This can be used as a light source in which a plurality of organic EL elements are arranged along the longitudinal direction of the photoreceptor.

Example 1 Synthesis of Exemplary Compound (2) Compound (16) and compound (17) were respectively synthesized by the following methods and used for the next coupling.

In a reaction vessel purged with nitrogen, 60 mL of toluene, 30 mL of ethanol, 30 mL of 10 wt% aqueous sodium carbonate, 35.7 mg of tetrakis (triphenylphosphine) palladium, 403.1 mg of the previously prepared compound (16), and compound (17) 350. In order to remove oxygen remaining in the system, 2 mg was bubbled with argon gas for several minutes. The reaction mass was heated with a temperature-controlled heating medium and refluxed for 12 hours. After cooling to room temperature, the mixture was neutralized with an aqueous ammonium chloride solution and extracted with chloroform. After liquid separation, the organic layer was dried over anhydrous magnesium sulfate, and the desiccant was removed by filtration. The crude product obtained by concentration was purified by column chromatography and GPC to obtain 230 mg of compound (2). Compound (2) was identified by NMR and MALDI-TOF.
¹ H-NMR (CDCl ₃ , 400 MHz)
δ = 1.61 ppm (s, 6H), 1.63 ppm (s, 6H), 7.34-7.41 ppm (m, 4H), 7.49-7.50 ppm (m, 2H), 7.77- 7.96 ppm (m, 10H), 8.05-8.30 ppm (m, 10H), 8.49 (dd, 2H).
MALDI-TOF m / z = 712.16 (calc.m / z = 712.31)

  When the DSC measurement and TG-DTA measurement of the obtained compound (2) were performed, the glass transition temperature was 149.9 ° C., the melting point was 256.7 ° C., and the decomposition start temperature was 454.5 ° C. The conversion temperature could not be observed. The results are summarized in Table 1.

  The compound (1) and the compounds (3) to (15) can be synthesized in the same manner as in Example (1) by changing to the compounds described in the table below for intermediates.

(Example 2)
An organic EL device having the structure shown in FIG. 4 was prepared by the following method.

  What formed indium tin oxide (ITO) as an anode 2 with a film thickness of 120 nm on a glass substrate as a substrate 1 by a sputtering method was used as a transparent conductive support substrate. This was ultrasonically washed successively with acetone and isopropyl alcohol (IPA), then boiled and washed with IPA and then dried. Furthermore, what was UV / ozone cleaned was used as a transparent conductive support substrate.

  Using a compound (18) represented by the following structural formula as a hole injection material, a 0.1 wt% chloroform solution was prepared.

This solution was dropped on the ITO electrode and spin-coated to form a film. The thickness of the formed hole injection layer 7 was 11 nm.
A hole transport layer was formed on the hole injection layer 7 by vapor-depositing a compound (19) represented by the following structural formula. The formed hole transport layer 5 had a thickness of 15 nm.

  Next, as the light emitting layer 3 on the hole transport layer 5, the compound (20) having the following structure and the exemplified compound (2) are co-deposited (weight ratio 5:95) to provide the light emitting layer 3 having a thickness of 30 nm. It was.

  Further, 2,9- [2- (9,9′-dimethylfluorenyl)]-1,10-phenanthroline was formed as the electron transport layer 6 to a thickness of 30 nm by vacuum deposition.

  Next, lithium fluoride (LiF) is formed on the previous organic layer by a thickness of 0.5 nm by a vacuum deposition method, and an aluminum film having a thickness of 150 nm is further provided by a vacuum deposition method. Electron injection electrode (cathode 4) An organic EL element was prepared.

  The obtained organic EL device was covered with a protective glass plate in a dry air atmosphere and sealed with an acrylic resin adhesive so that the device did not deteriorate due to moisture adsorption.

  When the ITO electrode (anode 2) was the positive electrode and the Al electrode (cathode 4) was the negative electrode, good blue light emission was observed in the device thus obtained.

Comparative Example 1 Synthesis of Comparative Example Compound As a comparative example, compound (18) having the following structure was synthesized by the following method.

  The obtained compound (18) was subjected to DSC and TG-DTA measurement. As a result, the glass transition temperature was 109.3 ° C., the crystallization temperature was 186.2 ° C., the melting point was 247.9 ° C., and the decomposition start temperature was 400. It was 6 ° C. The results are shown in Table 2.

  The compound (18) of Comparative Example 1 does not have a fluorene ring at the 7-position of the pyrene ring. As a result, compared with the compound (2) of Example 1, the glass transition temperature is low, crystallization is observed, the melting point is low, and the decomposition temperature is low.

That is, the compound (18) of Comparative Example 1 is considered to be weak against thermal influences, while the pyrene compound according to the present invention is a stable compound excellent in thermal influences.
From this, it is considered that the pyrene compound according to the present invention can be preferably used for an organic EL device.

The cross-sectional schematic diagram of the organic EL element which has a pyrene compound which concerns on this invention. The cross-sectional schematic diagram of the organic EL element which has a pyrene compound which concerns on this invention. The cross-sectional schematic diagram of the organic EL element which has a pyrene compound which concerns on this invention. The cross-sectional schematic diagram of the organic EL element which has a pyrene compound which concerns on this invention. The cross-sectional schematic diagram of the organic EL element which has a pyrene compound which concerns on this invention.

Explanation of symbols

1 Substrate 2 Anode 3 Light-Emitting Layer 4 Cathode 5 Hole Transport Layer 6 Electron Transport Layer 7 Hole Injection Layer 8 Hole / Exciton Blocking Layer

Claims (5)

A pyrene compound represented by the general formula (1).

In the formula, FL represents a substituted or unsubstituted fluorenyl group.
A1 represents a substituted or unsubstituted benzene ring, a substituted or unsubstituted naphthalene ring, or a substituted or unsubstituted fluorene ring.
A2 represents a substituted or unsubstituted aryl group.   The pyrene compound according to claim 1, wherein A2 in formula (1) is an aryl group having 1 to 3 rings.   In the organic EL element which has an anode, a cathode, and the organic compound layer arrange | positioned between the said anode and a cathode, the said organic compound layer has a pyrene compound as described in any one of Claim 1 thru | or 2. A characteristic organic EL element.   An image display apparatus comprising the organic EL element according to claim 3 in a display unit.   An image pickup apparatus comprising the image display apparatus according to claim 4 in a display unit.

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