WO2012085985A1 - Polymer compound and method for producing same - Google Patents

Abstract

In order to provide an electron transporting material that is suitable for forming an organic EL element having an inverted structure by using a wet process, a polymer compound having a triarylphosphine oxide as the skeleton thereof is produced. An organic EL element (110) is constructed by successively forming, on the surface of a substrate (101), a cathode (102), an electron injection layer (104), a light emission layer (105), a hole transport layer (106), a hole injection layer (107), and an anode (108). The electron injection layer (104) is formed by applying, between banks (103), an ink prepared by dissolving said polymer compound into an alcohol solvent, and drying the ink. The light emission layer (105) is formed by applying, between the banks (103), an ink prepared by dissolving, into a nonpolar solvent, a light-emission-layer material such as a polyphenylenevinylene (PPV) derivative or a polyfluorene derivative, and drying the ink.

Description

Polymer compound and production method thereof

The present invention relates to an organic phosphine oxide compound used for an electron transport material of an organic electroluminescence (EL) element and a method for producing the same.

An organic EL element is a light emitting element using an electroluminescence phenomenon of an organic compound, and since it can easily obtain bright light emission with high luminance, it has been put into practical use in a display device, a lighting device, and the like.

In order to further spread the organic EL element, it is necessary to manufacture the organic EL element at a lower cost than a liquid crystal display, a fluorescent lamp, and LED lighting. For this reason, it is desired to simplify the structure and manufacturing method of the organic EL element. ing.

Currently, as described in Patent Document 1, the most widely used organic EL element has an anode formed on the substrate side, an organic layer formed by a vacuum film forming method, and a cathode formed on the organic layer. Recently, as disclosed in Patent Document 2, a method of forming an organic layer by a wet method in which an ink containing an organic layer forming material is applied and dried is disclosed, as disclosed in Patent Document 2, and various polymers are disclosed. Many organic EL devices having a structure in which a light-emitting layer is formed by dissolving a system material in a nonpolar solvent and applying it have been developed.

According to this wet method, an organic layer can be formed without using a vacuum device, and a light emitting layer and the like can be formed relatively easily even in a large panel, which is preferable from the viewpoint of manufacturing time.

Non-Patent Document 1 discloses an inverted structure in which organic EL elements are stacked in the reverse order, that is, a structure in which a cathode is formed on a substrate side and an anode is formed on an organic layer. Has been.

Developing an organic EL element having such an inverted structure has the advantage that, in designing the device structure of the organic EL element, the selection range is widened and the degree of freedom in design is improved.

In particular, when an active matrix organic EL device is realized by forming a transistor array on a large substrate and forming an organic EL element array thereon, an amorphous silicon, a microcrystalline silicon, an oxide semiconductor ( It is desirable to form an n-type TFT having a high-speed response using a channel material of indium-zinc-gallium oxide or the like. However, when an n-type TFT is used, a simple structure comprising two TFTs and one capacitor is used. In order to realize driving with a pixel circuit, the organic EL element needs to have an inverted structure.

Japanese Patent Laid-Open No. 2-15595 Japanese National Patent Publication No. 4-500582 WO2005-104628 JP 2007-053286 A

Even in an organic EL element having an inverted structure, if an organic layer such as a light emitting layer can be formed by a wet method, it is advantageous for realizing a large organic EL device. When the material is formed by a wet method, the material of the electron injection layer or electron transport layer formed thereunder is not only contained in the ink for forming the organic layer in addition to having film formability and electron transport performance. It is also required to have properties that do not dissolve in polar solvents.

However, it is difficult to find a material having these required performances.

For example, Patent Document 3 discloses an electron transporting material that can be applied by a wet method. When an electron injection layer or an electron transporting layer is formed of these electron transporting materials, a light emitting layer or the like is formed thereon. When the organic layer is applied by a wet method, the electron transporting material is dissolved in the nonpolar solvent of the organic layer forming ink, so that the film structure cannot be maintained. Therefore, it is difficult to use as a material for forming an electron injection layer or an electron transport layer of an organic EL element having an inverted structure.

Further, Patent Document 4 discloses an organic EL device having an inverted structure, and also discloses a method of forming an electron injecting metal oxide layer by applying an inorganic material such as zinc oxide. In general, high-temperature treatment is required to form an oxide layer, which is not a simple manufacturing method. Since the electron injection capability of the formed metal oxide layer is low, a high voltage is required for driving the organic EL element, and the efficiency is also low. In addition, the formed metal oxide layer is generally poor in homogeneity, the film surface is rough, and short-circuiting due to pinholes is likely to occur, so that it is difficult to obtain stable characteristics.

Under such circumstances, it has not yet been possible to realize an organic EL element having an inverted structure with high performance and long life by forming an organic layer such as a light emitting layer by a wet method.

The present invention has been made in view of such problems, and an object thereof is to provide an electron transporting material suitable for forming an organic EL element having an inverted structure using a wet method.

In order to solve the above problems, a polymer compound according to one embodiment of the present invention is represented by the general structural formula (1).

Here, in the formula (1), Ar 1 and Ar 2 are monovalent aromatic residues which may be the same or different from each other, and Ar 3 and Ar 4 may be the same or different from each other 2 Valent aromatic residue. n is a natural number of 2 or more.

All of the polymer compounds represented by the general structural formula (1) have triarylphosphine oxide in the skeleton.

A compound having an organic phosphine oxide skeleton is basically known as an electron transporting material, but the compound having the organic phosphine oxide skeleton is dissolved in a nonpolar solvent by being in the form of a polymer compound. It becomes insoluble by reducing the properties.

Therefore, when the electron injection layer or the electron transport layer is formed from the polymer compound of the above aspect, the electron injection layer or the electron transport is formed when the electron injection layer or the electron transport layer is formed thereon by a wet method in which a liquid containing an organic material and a nonpolar solvent is applied. Since the layers do not dissolve, the laminated structure of the organic layers can be stably formed.

In addition, the compound of the above aspect is in the form of a polymer compound, but the electron transport property of the organic phosphine oxide compound is not impaired thereby, and the electron transport property is maintained.

As described above, according to the polymer compound of the above aspect, the laminated structure of the organic layer in the inverted organic EL element can be stably formed, so that the emission luminance is uniform and the lifetime of the element is increased. be able to.

In addition, since the organic layer formed with the organic phosphine oxide compound of the above embodiment is insoluble in the nonpolar solvent, the material of the organic layer formed thereon is widely selected from organic materials that are soluble in the nonpolar solvent. be able to. That is, when the organic layer formed thereon is a light emitting layer, the selection range of the light emitting material used for the light emitting layer is widened.

If the organic EL element has an inverted structure in which a cathode is provided on the substrate side, the TFT and the cathode can be easily connected even when an n-channel TFT having excellent switching characteristics is formed on the TFT substrate. Can be connected. Therefore, it is particularly suitable when an n-channel TFT is formed on the substrate.

Therefore, the polymer compound according to this embodiment contributes to widening the selection range in designing an organic EL device having an inverted structure, and has high practical value.

It is sectional drawing which shows typically the organic EL element of the inverted structure which concerns on embodiment. 1 is a plan view showing a part of a display panel 100 in which organic EL elements 110 are arranged on a substrate 101. FIG. 1 is a diagram showing a configuration of a display device 200 using a display panel 100. FIG. It is an external appearance which shows an example of the television system using the display apparatus 200. FIG. 1 is a schematic cross-sectional view illustrating a configuration of an organic EL element according to Example 1. FIG. It is a figure which shows the test result which investigated toluene durability about the organic phosphine oxide compound concerning an Example. It is a figure which shows the test result which investigated toluene durability about the organic phosphine oxide compound concerning an Example. It is a figure which shows the test result which investigated toluene durability about the organic phosphine oxide compound concerning a comparative example. It is a figure which shows the synthesis | combining method of the organic phosphine oxide compound concerning an Example. It is a figure which shows the synthesis | combining method of the organic phosphine oxide compound concerning an Example.

<Aspect of the Invention>
The polymer compound according to one embodiment of the present invention is represented by the general structural formula (1).

Here, in the formula (1), Ar 1 and Ar 2 are monovalent aromatic residues which may be the same or different from each other, and Ar 3 and Ar 4 may be the same or different from each other 2 Valent aromatic residue. n is a natural number from 2 to 2000.

Alternatively, the polymer compound according to one embodiment of the present invention is represented by the general structural formula (2).

Here, in the formula (2), Ar 1 and Ar 2 are aromatic residues which may be the same or different from each other, and R 1 and R 2 may be the same or different from each other. An aliphatic substituent. n is a natural number from 2 to 2000.

Each of the polymer compounds represented by the general structural formulas (1) and (2) has triarylphosphine oxide in the skeleton.

A compound having an organic phosphine oxide skeleton is basically known as an electron transporting material, but the compound having the organic phosphine oxide skeleton is dissolved in a nonpolar solvent by being in the form of a polymer compound. It becomes insoluble by reducing the properties.

Therefore, when the electron injection layer or the electron transport layer is formed from the polymer compound of the above aspect, the electron injection layer or the electron transport is formed when the electron injection layer or the electron transport layer is formed thereon by a wet method in which a liquid containing an organic material and a nonpolar solvent is applied. Since the layers do not dissolve, the laminated structure of the organic layers can be stably formed.

In addition, the compound of the above aspect is in the form of a polymer compound, but the electron transport property of the organic phosphine oxide compound is not impaired thereby, and the electron transport property is maintained.

As described above, according to the polymer compound of the above aspect, the laminated structure of the organic layer in the inverted organic EL element can be stably formed, so that the emission luminance is uniform and the lifetime of the element is increased. be able to.

In particular, the polymer compound represented by the structural formula (3) is preferable because it is excellent in electron transport properties and has low solubility in a nonpolar solvent.

Here, in Equation (3), n is a natural number from 2 to 2000.

In the polymer compounds represented by the above formulas (1) to (3), the weight average molecular weight is preferably 2000 or more in view of sufficient insolubility in a nonpolar solvent. In consideration of applying the polymer compound by a wet method to form an organic layer, the weight average molecular weight Mw of the polymer compound is preferably 1,000,000 or less.

In the method for producing a polymer compound according to one embodiment of the present invention, the compound represented by the general structural formula (4) and the compound represented by the general formula (5) are condensed in a solvent in the presence of a condensation catalyst and a base to be polymerized. Thus, a polymer compound is obtained.

In the formulas (4) and (5), Ar1 to Ar4 are aromatic residues which may be the same or different from each other. X is a halogen atom selected from iodine, bromine and chlorine.

According to the experiment of the present inventor, it is known that the polymer compound of interest can be synthesized while suppressing the occurrence of side reactions according to the method for producing a polymer compound of the above aspect.

Ar 1 to Ar 4 included in the structural formulas (1), (2), (4), and (5) will be described in further detail.

Ar1 and Ar2 are monovalent “aromatic residues” and may be the same or different from each other. Monocyclic aromatic residues such as benzene ring, thiophene ring, triazine ring, furan ring, pyrazine ring, pyridine ring and heterocycle, naphthalene ring, anthracene ring, thieno [3,2-b] thiophene ring, phenanthrene ring Condensed polycyclic aromatic residues such as fluorene ring and furo [3,2-b] furan ring, and aromatic residues such as heterocyclic ring, biphenyl ring, terphenyl ring, bithiophene ring and bifuran ring Group and heterocyclic ring, acridine ring, isoquinoline ring, indole ring, carbazole ring, carboline ring, quinoline ring, dibenzofuran ring, cinnoline ring, thionaphthene ring, 1,10-phenanthroline ring, phenothiazine ring, purine ring, benzofuran ring, silole ring And those consisting of a combination of an aromatic residue and a heterocyclic ring. Moreover, one or more of hydrogen atoms of these aromatic residues may be substituted with an alkyl group, a diarylphosphinoyl group, or the above-described aromatic residue.

Ar3 and Ar4 are divalent “aromatic residues” and represent an arylene group, an alkenylene group, an alkynylene group or a divalent heterocyclic group.

The arylene group usually has 6 to 60 carbon atoms, preferably 6 to 20 carbon atoms, and includes a phenylene group (a group numbered 1 to 3 in the chemical formula 10 below), a naphthalenediyl group (a number 4 to 13 in the chemical formula 10 below). Group), anthracenylene group (group numbered 14-19 in the chemical formula 10 below), biphenylene group (group numbered 20-23 in the chemical formula 10 below), triphenylene group (numbers 24-26 in the chemical formula 10 below). And a condensed ring compound group (groups numbered 27 to 33 in the following chemical formula 10). Further, one or more hydrogen atoms of these arylene groups may be substituted with an alkyl group, a diarylphosphinoyl group, or the above-described monovalent aromatic residue. However, the carbon number of the arylene group does not include the carbon number of the substituent.

The divalent heterocyclic group refers to a remaining atomic group obtained by removing two hydrogen atoms from a heterocyclic compound, and usually has 2 to 60 carbon atoms, preferably 4 to 20 carbon atoms. Here, the heterocyclic compound is an organic compound having a cyclic structure in which the elements constituting the ring include not only carbon atoms but also heteroatoms such as oxygen, sulfur, nitrogen, phosphorus, and boron in the ring. Say. Examples of divalent heterocyclic groups are shown below. Further, one or more hydrogen atoms of these arylene groups may be substituted with an alkyl group, a diarylphosphinoyl group, or the above-described monovalent aromatic residue. However, the carbon number of the divalent heterocyclic group does not include the carbon number of the substituent.

A divalent heterocyclic group containing nitrogen as a heteroatom; a pyridine-diyl group (group numbered 34 to 39 in the following chemical formula 11), a diazaphenylene group (group numbered 40 to 43 in the chemical formula 11 below), Quinolinediyl groups (groups numbered 44-58 in Chemical Formula 11 below), quinoxalinediyl groups (groups numbered 59-63 in Chemical Formula 11 below), acridinediyl groups (numbered 64-67 in Chemical Formula 11 below) Groups), bipyridyldiyl groups (groups numbered 68 to 70 in the following chemical formula 11), phenanthroline diyl groups (groups numbered 71 to 73 in the chemical formula 11 below), and the like.

A group having a fluorene structure containing silicon, nitrogen, sulfur, selenium, phosphorus atoms, etc. as heteroatoms (groups numbered 74 to 91 in the chemical formula 11 below). In addition, it is desirable in terms of light emission efficiency to have an aromatic amine monomer such as a carbazole group containing nitrogen atoms (groups numbered 77 to 79 in the following chemical formula 11) or a triphenylamine diyl group.

Examples of heteroatoms include 5-membered ring heterocyclic groups containing silicon, nitrogen, sulfur, selenium, phosphorus atoms, etc. (groups numbered 92 to 96 in the chemical formula 12 below).

5-membered condensed heterocyclic groups containing silicon, nitrogen, sulfur, selenium, etc. as heteroatoms: (groups numbered 97 to 108 in the chemical formula 12 below), benzothiadiazole-4,7-diyl groups and benzoxa And diazole-4,7-diyl group.

A 5-membered ring heterocyclic group containing silicon, nitrogen, sulfur, selenium, etc. as a heteroatom, and bonded to the α-position of the heteroatom to form a dimer or oligomer: Group with 117).

A 5-membered ring heterocyclic group containing silicon, nitrogen, sulfur, selenium, etc. as a heteroatom, which is bonded to the phenyl group at the α-position of the heteroatom: (numbers 111 to 117 are attached in the following chemical formula 12) Group).

In the above formulas 11 and 12, R ′, R ″, and R ″ ″ in the formula each independently represent an alkyl group, an aryl group, or a monovalent heterocyclic group. Among these, the aryl group and the heterocyclic group may be substituted with an alkyl group, a diarylphosphinoyl group, or the above-described monovalent aromatic residue.

Hereinafter, an embodiment in which the organic phosphine oxide compound according to the present invention is applied to an electron injection layer of an organic EL element having an inverted structure will be described.

<Embodiment>
(Configuration of display panel 100)
FIG. 1 is a cross-sectional view schematically showing an inverted-structure organic EL element according to an embodiment, in which one of the organic EL elements is cut perpendicularly to a substrate (along the X direction in FIG. 2). A cut section) is shown.

As shown in FIG. 1, a cathode 102, an electron injection layer 104, a light emitting layer 105, a hole transport layer 106, a hole injection layer 107, and an anode 108 are sequentially formed on the surface of a substrate 101 to form an organic EL element 110. Is configured. The organic EL element 110 is a bottom emission type, and takes out light emitted from the light emitting layer 105 downward.

The substrate 101 may be a simple glass substrate, a silicon substrate, or a sapphire substrate, or may be a substrate on which metal wiring is formed. Here, the substrate 101 is planarized on which a transistor array is formed. A TFT substrate on which a film is formed is formed, and organic EL elements are arranged in a matrix on the substrate 101 to form a display panel 100, which can be driven by an active matrix method.

FIG. 2 is a plan view showing a part of the display panel 100 in which the organic EL elements 110 are arranged on the substrate 101. In this figure, the organic EL elements 110a to 110c correspond to RGB sub-pixels. As shown in FIG. 3, in the display panel 100, the sub-pixels composed of the organic EL elements 110 are arranged in a matrix in the vertical and horizontal directions (XY directions), and one pixel is formed by the adjacent RGB three-color sub-pixels. Adjacent organic EL elements 110 a, 110 b, 110 c are partitioned by a bank 103.

FIG. 3 is a diagram showing a configuration of a display device 200 using the display panel 100.

The display device 200 includes a display panel 100 and a drive control unit 120 connected thereto. The drive control unit 120 is composed of four drive circuits 121 to 124 and a control circuit 125.

FIG. 4 is an external shape showing an example of a television system using the display device 200.

(Configuration of organic EL element 110)
Hereinafter, the configuration of the organic EL element 110 will be described in detail with reference to FIG.

The substrate 101 is configured by sequentially forming TFTs, line wirings, and a planarizing film on the main surface of a glass substrate.

In a large panel, it is preferable to form a μc-Si TFT made of microcrystalline silicon as a TFT.

The μc-Si TFT has less variation in the threshold voltage in the substrate surface than a TFT made of low-temperature polysilicon, and the threshold voltage when DC is applied is more stable than a TFT made of amorphous silicon. In addition, when the TFT formed on the substrate 101 is an n-channel TFT, excellent switching characteristics can be obtained as compared with a P-channel TFT.

The planarizing film is made of an organic material having excellent insulating properties, such as polyimide, polyamide, and acrylic resin material, and covers the arranged TFTs as a whole. A via for wiring is formed in the planarizing film.

A cathode 102 is laminated on the surface of the substrate 101. The cathode 102 is formed in a rectangular shape in a region corresponding to each subpixel on the planarizing film of the substrate 101, and the cathodes 102 of all subpixels have the same size.

The cathode 102 is connected to the TFT by a via formed in the planarizing film.

The material for forming the cathode 102 is not particularly limited, but it is preferable to use a metal, a conductive oxide, or a conductive polymer.

Examples of metals include aluminum, silver, molybdenum, tungsten, titanium, chromium, nickel, zinc, and alloys containing any of them.

Examples of the conductive oxide include indium tin oxide, indium zinc oxide, and zinc oxide.

Examples of the conductive polymer include polyaniline, polythiophene, and those mixed with an acidic or basic substance.

A bank 103 is formed along the gap between adjacent cathodes 102.

The bank 103 includes a bank element 103a extending in the Y direction and a bank element 103b extending in the X direction in FIG. 2, and partitions adjacent sub-pixels as described above. The cross-sectional shape of each bank 103 is substantially trapezoidal, and the bank width is uniform.

The bank 103 is formed of an insulating organic material (for example, acrylic resin, polyimide resin, novolac type phenol resin, etc.), and the surface has water repellency.

In the recesses partitioned by the bank 103, the electron injection layer 104 and the light emitting layer 105 are formed in this order on the cathode 102, and the size of the subpixels surrounded by the bank 103 is also equal.

The material of the electron injection layer 104 is a polymer compound having an organic phosphine oxide skeleton, details of which will be described later.

The light emitting layer 105 is formed such that a light emitting layer 105a that emits blue light, a light emitting layer 105b that emits green light, and a light emitting layer 105c that emits red light are arranged in the horizontal direction (X direction in FIG. 2). ing.

As the material of the light emitting layer 105, it is preferable to use a polymer material, for example, a π-conjugated polymer material or a low molecular dye-containing polymer material. However, the material of the light emitting layer 105 may be a low molecular weight material as long as it is a material that dissolves in a nonpolar solvent.

Typical examples of the polymer material include polyphenylene vinylene (PPV (poly (phenylene vinylene)) derivatives or polyfluorene derivatives.

As described above, since the light emitting layer 105 can be formed by a printing technique by using a polymer light emitting material, it is suitable for producing a large display panel in a large amount at a low cost.

The cathode 102 and the electron injection layer 104 are made of a common material for the three colors of organic EL elements. However, the light emitting layer 105 is divided into blue, green, and red for the three colors of organic EL elements 110. It is made of a light emitting material that emits light.

A hole transport layer 106, a hole injection layer 107, and an anode 108 are formed so as to cover the light emitting layer 105 and the bank 103, and an organic EL element is configured. The hole transport layer 106, the hole injection layer 107, and the anode 108 are layers that are common to all organic EL elements 110 arranged on the substrate 101.

The hole transport layer 106 can be formed by depositing a hole transport material such as an aromatic amine including a triphenylamine derivative.

The hole injection layer 107 can be formed by forming a thin film of a hole injection metal oxide such as molybdenum oxide, tungsten oxide, or vanadium oxide.

The anode 108 is a common electrode common to all the organic EL elements 110. The material of the anode 108 is not particularly limited, but it is preferable to use a metal or a conductive oxide.

Examples of metals that can be used include aluminum, silver alloys, molybdenum, tungsten, titanium, chromium, nickel, zinc, and alloys thereof.

As examples of the conductive oxide, indium tin oxide, indium zinc oxide, zinc oxide, and the like can be used.

A sealing layer may be provided on the anode 108. This sealing layer is formed of a material such as SiN (silicon nitride) or SiON (silicon oxynitride).

(Details about the electron injection layer 104)
The electron injection layer 104 is mainly formed of a polymer compound having an organic phosphine oxide skeleton. As will be described in detail later, this polymer compound having an organic phosphine oxide skeleton has a structure in which three aromatic residues are bonded to phosphine oxide, and its electron-accepting property makes it excellent in electron transporting properties. It has characteristics suitable as a material for the injection layer 104. In addition, since it is a polymer compound, it is less soluble in nonpolar solvents than low molecular weight compounds. Here, in the polymer compound having an organic phosphine oxide skeleton, the weight average molecular weight is preferably set to 2000 or more in order to obtain insolubility in a nonpolar solvent.

In addition, when the polymer compound having an organic phosphine oxide skeleton is applied by a wet method, it is dissolved and applied in a polar solvent. However, when the weight average molecular weight is increased, it is difficult to dissolve in a polar solvent. The molecular weight is preferably 1,000,000 or less.

Hereinafter, preferred organic structures for the organic phosphine oxide compound constituting the electron injection layer 104 are listed.

In the formula (1), Ar 1 and Ar 2 are monovalent aromatic residues which may be the same or different from each other, and Ar 3 and Ar 4 are divalent which may be the same or different from each other. Is an aromatic residue. n is a natural number from 2 to 2000.

The aromatic residue may be a phenyl group which is a simple aromatic ring structure, a polycyclic aromatic ring structure such as a naphthyl group, or a heterocyclic structure.

In the formula (2), Ar1 and Ar2 are aromatic residues which may be the same or different from each other, and R1 and R2 may be the same or different from each other. Group substituents. n is a natural number from 2 to 2000.

Here, in Expression (3), n is a natural number from 2 to 2000.

The electron injection layer 104 is formed mainly of a polymer compound having such an organic phosphine oxide skeleton, and may contain an alkali metal, an alkaline earth metal, or a rare earth metal, thereby injecting an electron. Can be improved.

As a mechanism for improving the electron injecting property, alkali metals, alkaline earth metals, and rare earth metals have electron donating properties. Therefore, electrons are given to organic phosphine oxide compounds that are electron accepting, and radical anion states are given to the compounds. Form. The radical anion species behaves as a movable electron, and the conductivity of the electron injection layer 104 is improved.

As a form in which the electron injection layer 104 contains an alkali metal, an alkaline earth metal, or a rare earth metal, it is preferable to mix these metals in the form of an organometallic complex. If mixed in the form of metal, it is difficult to disperse in the solvent and the metal is easily oxidized. However, mixing in the form of an organometallic complex facilitates dispersion in the solvent and prevents metal oxidation. Because.

The ratio of mixing the alkali metal, alkaline earth metal, rare earth metal, or metal complex thereof is preferably 1% to 90% by weight with respect to the polymer compound having an organic phosphine oxide skeleton, and further 5 % To 30% is preferable.

As the alkali metal, lithium, sodium, potassium, rubidium and cesium are preferable. As the alkaline earth metal, magnesium, calcium, strontium and barium are preferable. As the rare earth metal, lanthanum, cerium, erbium, europium, scandium, yttrium, and yttrium are preferable.

The type of ligand of the metal complex is not particularly limited, but preferred examples include acetylacetone, 2,2,6,6-tetramethylheptane-3,5-dione (TMHD), dipivaloylmethane, and dibenzoylmethane. Β-diketones such as oxine, and oxines such as oxine and 2-methyloxin.

(Manufacturing method of display panel 100)
An example of a method for manufacturing the display panel 100 will be described.

Step of manufacturing the substrate 101:
A TFT layer composed of TFT and wiring, SD electrode, and μc-Si is formed by a reactive sputtering method or a thin film formation method using plasma.

Then, a substrate 101 is formed by forming a planarizing film so as to cover the TFT.

The organic EL elements 110 of the respective colors are formed on the substrate 101 thus manufactured as follows.

Step of forming cathode 102:
On the planarizing film, the cathode 102 is formed by forming a thin film of a metal material for the cathode 102 by sputtering and patterning it by wet etching.

Bank 103 formation process:
Next, as a bank material, for example, a photosensitive resist material or a resist material containing a fluorine-based or acrylic-based material is applied on the planarization film, and is patterned by a photoresist method to form the bank 103.

In this bank forming step, the surface of the bank 103 is subjected to a surface treatment with an alkaline solution, water, an organic solvent or the like in order to adjust the contact angle of the bank 103 with respect to the ink to be applied next or to impart water repellency to the surface. Alternatively, plasma treatment may be performed.

Step of forming the electron injection layer 104:
An electron injection layer 104 is formed on the cathode 102 by a wet method.

In this step, the above-described electron injection layer material (polymer compound having an organic phosphine oxide skeleton, or an alkali metal, alkaline earth metal, rare earth metal, or metal complex thereof) is dissolved in a polar solvent. The electron-injecting layer 104 is formed by applying the dried ink between the banks 103 and drying.

As a polar solvent for dissolving the material of the electron injection layer 104, for example, a solvent having an OH group such as an alcohol type or a glycerin type can be used.

Specific examples include methanol, ethanol, propanol, isopropanol, butyl alcohol, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, and glycerin. A mixed solution of these and water may be used.

The solvent may be a single solvent or a mixture of many kinds of solvents. A mixed solvent obtained by mixing a plurality of polar solvents may be used, or a mixed solvent of a polar solvent and a nonpolar solvent may be used.

The concentration of the material for the electron injection layer is preferably 0.05 wt% to 5 wt% in a liquid obtained by mixing the material for the electron injection layer and a polar solvent.

As the coating method, an inkjet method, a dispenser method, a nozzle coating method, intaglio printing, letterpress printing, and the like can be used.

Step of forming the light emitting layer 105:
A light emitting layer 105 is formed on the electron injection layer 104 by a wet method.

In this step, an ink in which the above-described light emitting layer material is dissolved in a solvent is applied between the banks 103 and dried. The material used is different for each emission color. In this ink, the solvent that dissolves the material of the light emitting layer 105 is a nonpolar solvent.

It is preferable to use an aromatic solvent as the nonpolar solvent. Specifically, a solvent having a benzene ring as the center, such as toluene or xylene, or a heterocyclic aromatic solvent such as pyridine can be preferably used.

Examples of nonpolar solvents other than aromatic solvents include linear or branched aliphatic solvents such as hexane and 2-methylhexane, cycloaliphatic solvents such as cyclohexane, and halogens such as chloroform. Or an aliphatic aliphatic solvent such as tetrahydrofuran may be used.

The solvent used here may be a single solvent or a mixed solvent obtained by mixing many kinds of solvents.

As a method for applying the ink, an ink jet method, a dispenser method, a nozzle coating method, intaglio printing, letterpress printing, and the like can be used.

Step of forming hole transport layer 106:
A material for the hole transport layer 106 and a solvent are mixed at a predetermined ratio to prepare an ink for the hole transport layer, and the ink is applied onto the light emitting layer 105.

The applied ink entirely covers the light emitting layer 105 and the bank 103.

As a method for applying the ink for forming the hole transport layer 106, an inkjet method, a dispenser method, a nozzle coating method, a spin coating method, intaglio printing, letterpress printing, or the like is used.

The hole transport layer 106 is formed by drying the ink thus applied.

Step of forming hole injection layer 107:
The hole-injection layer 107 can be formed into a thin film using a metal oxide material such as molybdenum oxide or tungsten oxide by a vacuum evaporation method or the like.

Step of forming anode 108:
An anode 108 is formed on the surface of the hole injection layer 107 by depositing a material such as ITO or IZO by vacuum deposition or sputtering.

When forming the sealing layer on the surface of the anode 108, it can be formed by depositing a material such as SiN (silicon nitride) or SiON (silicon oxynitride) by a vacuum deposition method.

Through the above steps, an organic EL element is formed on the substrate, and the display panel 100 is completed.
(Method for producing polymer compound)
A method for producing the polymer compound represented by the general structural formula (1) will be described.

A compound represented by the general structural formula (4) shown in the following chemical formula 16 and a compound of the general structural formula (5) are condensed in a solvent in the presence of a condensation catalyst and a base and polymerized to give a general structural formula (1 ) Can be obtained.

In the formula (5), X is a halogen atom selected from iodine, bromine and chlorine.

The reaction temperature can be 60 ° C. to 180 ° C., but 80 ° C. to 150 ° C. is preferable from the viewpoint of reaction time and yield.

The solvent used in the polymerization is not particularly limited, but linear and branched (C1-C8) alcohols, ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, glycerol, dimethyl ether, dimethyl sulfoxide, dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran, dioxane, toluene, xylene, benzonitrile and the like are preferably used alone or in combination. In particular, ethylene glycol, ethylene glycol monomethyl ether, dimethyl ether, dimethyl sulfoxide, dimethylacetamide, N-methylpyrrolidone, tetrahydrofuran, and dioxane are preferable in terms of yield and reaction time.

The amount of the solvent is preferably 0.2 L to 100 L with respect to 1 mol of the monomer. More preferably, 1 L to 10 L is preferable in terms of yield and reaction rate.

The condensation catalyst is not particularly limited, but palladium and nickel compounds are preferred. For example, palladium acetate, palladium-activated carbon, tetrakis (triphenylphosphine) palladium (0), [1,1'-bis (diphenylphosphino) ferrocene] palladium (II) dichloride, tris (dibenzylideneacetone) dipalladium (0 ), [1,3-bis (diphenylphosphino) propane] dichloronickel (II) can be used alone or in combination.

The amount of the catalyst is not particularly limited, but 0.0001 mol to 0.5 mol is preferably used with respect to 1 mol of the monomer, and 0.001 mol to 0.1 mol is more preferable in terms of yield and reaction rate.

Furthermore, a ligand that can be added to the catalyst in the reaction solvent can also be used. The ligands include 1,2-bis (diphenylphosphino) ethane, 1,3-bis (diphenylphosphino) propane, 1,4-bis (diphenylphosphino) butane, tri-tert-butylphosphine, 2 -(Di-tert-butylphosphino) biphenyl and the like can be used. The amount of the ligand is preferably in the range of 0.1 to 10 mol, more preferably 0.5 to 5 mol with respect to 1 mol of the catalyst.

The method for synthesizing the bis (arylphosphinoyl) arylene monomer used in the reaction is not particularly limited, but can be synthesized by the following method.

In the reaction (1), a bis (arylphosphinoyl) arylene monomer is obtained by reacting a dilithioarylene compound with an arylchloroaminophosphine and then hydrolyzing with an acidic aqueous solution.

In reaction (2), a dilithioarylene compound and an arylphosphinic acid ester are reacted to obtain a bis (arylphosphinoyl) arylene monomer. In the formula, R is not particularly limited as long as it is an alkyl group or an aromatic residue stable to the organolithium compound.

In reaction (3), a bis (arylphosphinoyl) arylene monomer is obtained by reacting a dilithioarylene compound with dichloroarylphosphine and then hydrolyzing it.

Here, in the reaction (1), as compared with the reaction (3), there is one chloro group which is a reaction point, so that a side reaction hardly occurs, which is preferable in terms of yield. Further, the phosphinic acid ester used in the reaction (2) has a low activity and a low yield compared to phosphine chloride. Therefore, reaction (1) is most preferable.

The dilithio compound that is a raw material of the reactions (1) to (3) can be synthesized using a known method. For example, it can be obtained using a dihalogen compound and a lithiating agent such as butyl lithium.

The dilithiated compound can be replaced with the corresponding Grignard reagent.

(Effects of the organic EL element 110 and its manufacturing method)
In the organic EL element 110 described above, the electron injection layer 104 includes the polymer compound having the organic phosphine oxide skeleton described above. These polymer compounds are excellent in film formability, have a structure in which three aromatic residues are bonded to phosphine oxide, have electron accepting properties, excellent electron injecting properties, and are suitable for nonpolar solvents. And insoluble.

That is, a low molecular weight organic phosphine oxide compound such as triphenylphosphine oxide is known as an electron transporting material, but a high molecular weight organic phosphine oxide compound also has an electron having an organic phosphine oxide skeleton. Transport performance is maintained even in polymer systems.

In addition, the organic phosphine oxide compound has a phosphine oxide group which is a polar group, but also has an affinity for a nonpolar solvent such as toluene. Even in the case of an oxide compound, when it becomes a polymer compound, the solubility in a nonpolar solvent becomes low. Therefore, a layer formed of this polymer compound does not dissolve even when ink containing the nonpolar solvent comes into contact with the oxide compound.

On the other hand, since these polymer compounds are soluble in polar solvents such as alcohol, they can be formed by coating by a wet method. Moreover, the film forming property is also improved by using a polymer compound. This is because the low molecular weight compound tends to cause crystallization and thus the uniformity of the film may decrease, whereas the high molecular weight compound does not easily cause crystallization, and a uniform film quality can be easily obtained. Because.

Here, the polymer compound is less diffusible than the low molecular weight compound, and is difficult to dissolve in the solvent once dried. Therefore, if the electron injection layer 104 is formed of a polymer compound having an organic phosphine oxide skeleton, the ink in which the light emitting layer material is dissolved in a nonpolar solvent is wet in the step of forming the light emitting layer 105 on the electron injection layer 104. Even when the light emitting layer 105 is formed by coating by the method, the electron injection layer 104 is hardly dissolved.

Therefore, since the laminated structure of the electron injection layer 104 and the electron injection layer 104 can be stably formed, the light emission luminance can be made uniform and the life of the organic EL element 110 can be extended.

In addition, since the electron injection layer 104 is insoluble in the nonpolar solvent, it is possible to use various polymer materials that are soluble in the nonpolar solvent as the material of the light emitting layer 105. The range of luminescent materials that can be selected as materials is expanded.

The organic EL element 110 has an inverted structure in which the cathode 102 is provided on the substrate 101 side. In the inverted structure, an n-channel TFT is formed on the substrate 101 and connected to the cathode 102, and the anode A pixel structure in which 108 is a common electrode can be employed.

Further, by applying an n-channel TFT to the TFT, the driving speed of the organic EL element can be increased.

In particular, when μc-Si is used for the semiconductor layer of the driving TFT, only an n-channel TFT can be formed. In that case, the inverted structure of the organic EL element 110 may be applied.

As described above, the organic EL element 110 of this embodiment has a wide range of options when designing an organic EL element, and has practical value.

[Example]
[Solvent resistance test of electron transport materials]
6 (a) to (c) and FIG. 7, the polymer compound according to the example represented by the structural formulas (3) and (6) and the small molecule according to the comparative example represented by the structural formula (11) in FIG. The compounds were examined for durability against toluene as follows.

All of these compounds have a skeleton in which three aromatic residues are bonded to phosphine oxide, but the compounds represented by structural formulas (3) and (6) according to the examples are polymer compounds. On the other hand, the compound represented by the structural formula (11) is a low molecular weight compound. In addition, for the polymer compound represented by the structural formula (3) according to the examples, the weight average molecular weight Mw produced by the following synthesis method is Toluene durability was examined for 3300, those having a weight average molecular weight Mw of 10,000 and those having a weight average molecular weight Mw of 1821.

In addition, with respect to the polymer compound represented by the structural formula (6), toluene durability was examined for each of those having a weight average molecular weight Mw of 4703.

Test method:
A coating film of the polymer compound of each sample was formed on the surface of the quartz substrate. In the coating film forming method, a solution of each compound was applied onto a substrate by spin coating in the air, and was formed by vacuum drying at 100 ° C. for 30 minutes, and the film thickness was about 100 nm.

For the substrate on which each coating film was formed, the absorbance at each wavelength was measured with an absorptiometer. The measurement results are shown by spectral curves labeled “Before application of toluene” in FIGS.

Next, about the substrate on which each coating film was formed, 0.15 ml of toluene was dropped on the coating film, spin-coated at 500 rpm for 45 seconds, and dried at 130 ° C. for 30 minutes.

For each substrate, the absorbance at each wavelength was measured with an absorptiometer. The measurement results are shown by spectral curves labeled “After applying toluene” in FIGS.

The polymer compounds according to the examples represented by the structural formula (3) were measured for those having a weight average molecular weight MW of 10,000, 3300, and 1821, respectively. As shown in FIGS. 6 (a) and 6 (b), for MW3300 or more, the absorption spectrum curve is almost the same before and after application of toluene, and as shown in FIG. For the sample, the absorbance decreased after the toluene application, but the same waveform as before the toluene application was observed. Further, as shown in FIG. 7, the absorption spectrum curves of the polymer compound represented by the structural formula (6) are almost the same before and after the application of toluene.

Numerically, in the polymer compound of the structural formula (6), the absorbance before applying toluene and the absorbance after applying toluene were both 0.155 at a wavelength of 340 nm. This indicates that the coating film of the polymer compound represented by the structural formulas (3) and (6) is difficult to dissolve by applying toluene, that is, has high durability against toluene.

On the other hand, as shown in FIG. 8, with respect to the low molecular compound according to the comparative example represented by the structural formula (11), the absorption spectrum curve is changed before and after the application of toluene. Almost no absorbance is seen. Numerically, at a wavelength of 323 nm, the absorbance before application of toluene was 0.160, whereas the absorbance after application of toluene was 0.001. This shows that the coating film is almost dissolved by toluene application and does not remain.

From the above test results, the polymer compounds according to the examples represented by the structural formulas (3) and (6) have excellent durability against toluene as compared with the low molecular weight compound according to the comparative example represented by the structural formula (11). I understand.

In particular, when the polymer compound of the structural formula (3) is compared with the low molecular compound of the structural formula (11), the basic structure of the organic phosphine oxide compound is the same, but the polymer compound of the structural formula (3) is It is a chain polymer and has improved durability against toluene.

As described above, the durability against toluene is improved by using a chain polymer. In the chain polymer, the attractive force between the polymer molecules is increased and the molecular chain is entangled, and the solvent molecule is the molecular chain. It is thought that it becomes difficult to unravel the entanglement. And, as the molecular weight (degree of polymerization) of this chain polymer increases, the tendency increases, so that it becomes difficult to dissolve in a solvent.

Considering based on these test results, it is predicted that the durability against toluene is greatly improved by lengthening the molecular chain of an organic phosphine oxide compound having an aromatic residue.

That is, not only the polymer compounds represented by the structural formulas (3) and (6) but also the polymer compounds represented by the general structural formulas (1) and (2) have a structure in which an aromatic residue is bonded to phosphine oxide. In addition, since it is common to the chain polymer, the durability against toluene is considered to be good.

In addition, not only when the aromatic residue is a phenyl group, but also in the case of a compound having a polycyclic structure or a heterocyclic structure such as a naphthyl group, the use of a polymer compound improves the durability against toluene. To do.

In addition, the compounds according to the comparative examples represented by the formulas (23) to (28) in the following chemical formula 18 were also tested in the same manner. As a result, the absorption spectrum curve changed before and after the toluene application, and the toluene application Later, almost no light absorption was observed, indicating that the coating was dissolved.

From the above considerations, it can be seen that, in general, a compound having an organic phosphine oxide skeleton increases durability against toluene by using a polymer compound.

In addition, although the result of having tested with toluene as a nonpolar solvent was shown here, even if aromatic solvents (benzene, xylene, etc.) other than toluene are used, or an aromatic solvent and a saturated hydrocarbon solvent, Even when the test was conducted using the mixed solvent, the result of improving the durability was obtained.

In addition, the same result (durability improvement effect) was observed even when the test was performed only with a nonpolar solvent other than the aromatic solvent.

In general, polyvinylpyrrolidone, polyethylene glycol, and the like are known as nonionic and alcohol-soluble polymers, but most of the polymers having a phosphine oxide skeleton to which an aromatic residue is bonded as described above. It is not known and is a compound obtained by the present inventors through a new molecular design.

[Average molecular weight of polymer compound having organic phosphine oxide skeleton]
In the polymer compound having an organic phosphine oxide skeleton, the weight average molecular weight Mw of the polymer compound is preferably 2000 or more. This is because if the weight average molecular weight Mw is 2000 or more, it is sufficiently insoluble in a nonpolar solvent.

In addition, the weight average molecular weight Mw of the polymer compound is preferably 1,000,000 or less. This is because, when the polymer compound is applied by a wet method to form the electron transport layer 104, the polymer compound is dissolved and applied in a polar solvent. If the weight average molecular weight Mw is too large, the polymer compound is dissolved in the polar solvent. This is because it becomes difficult to apply by a wet method.

[Synthesis Method of Polymer Compound Having Organophosphine Oxide Skeleton]
A method for synthesizing the polymer compounds represented by the structural formulas (3) and (6) will be described.

First, an example of the polymer compound represented by the structural formula (3) will be described with reference to FIG.

1. Synthesis of chloro (diethylamino) phenylphosphine Chloro (diethylamino) phenylphosphine was synthesized based on the method of Sciffers et al.

I. Schiffers, T. Rantanen, F. Schmidt, W. Bergmans, L. Zani, and C. Bolm, J. Org. Chem. 1971, 71, 2472
Note that since chloro (diethylamino) phosphine is decomposed by moisture and oxygen, post-treatment in the synthesis of chloro (diethylamino) phosphine is performed in an argon atmosphere.

2. Synthesis of 2,7-bis (phenylphosphinoyl) -9,9-dimethylfluorene (monomer) In a nitrogen atmosphere at −80 ° C., 7.04 g of 2,7-dibromo-9,9-dimethylfluorene ( 27.5 mL (44 mmol) of 1.6M n-butyllithium hexane solution was added dropwise to 150 mL of 20 mmol) in THF over 30 minutes, and the mixture was stirred at −80 ° C. for 2 hours. This lithiates 2,7-dibromo-9,9-dimethylfluorene.

To this suspension, 10.4 g (48 mmol) of chloro (diethylamino) phenylphosphine was added, stirred at −80 ° C. for 20 minutes, and then stirred at room temperature for 14 hours.

While cooling the reaction solution in an ice bath, 25 mL of 12N hydrochloric acid was added and reacted at room temperature for 7 hours. After completion of the reaction, the reaction solution was diluted with 100 mL of water and neutralized with sodium bicarbonate. This solution was extracted with dichloromethane, the organic layer was dried over magnesium sulfate, and the solvent was removed under reduced pressure.

In the step of synthesizing 2,7-bis (phenylphosphinoyl) -9,9-dimethylfluorene, since the dihalogenated aryl is dilithiated, monophosphine oxide is also produced as a by-product in addition to the target product. The residue obtained was purified by column chromatography (silica gel, developing solvent: dichloromethane: methanol = 20: 1) to give 3.47 g of 2,7-bis (phenylphosphinoyl) -9,9-dimethylfluorene. Was obtained as a colorless oil (yield 39%).

The resulting product (monomer) was identified by measuring with MS and NMR.
MS (FAB +, 3-nitrobenzyl alcohol) m / z 443 (M + H)
¹ H NMR (CDCl ₃ , 60 Hz) d1.51 (s, 6H, CH ₃ ), d 7.56-8.04 (m, 16H), d8.17 (d, 2H, ¹ J = 481 Hz, PH)
3. Polymerization of 2,7-bis (phenylphosphinoyl) fluorene with 1,4-diiodobenzene 3-1
(1) 2,7-bis (phenylphosphinoyl) fluorene (monomer), diiodobenzene, catalyst, ligand and base were dissolved in a solvent, and the mixture was heated and stirred at a predetermined temperature for 20 hours.

The solvent, base, and reaction temperature conditions were changed as shown in Table 1. That is, DMA (dimethylacetamide) or NMP (N methylpyrrolidone) was used as the solvent, DIEA (diisopropylethylamine) or DMAP (dimethylaminopyridine) was used as the base, and the reaction temperature was 100 ° C. or 150 ° C.

It should be noted that better reproducibility can be obtained by degassing and dehydrating the solvent during the polymerization.

An example of the charged amount is shown below.

2,7-Bis (phenylphosphinoyl) -9,9-dimethylfluorene: 0.221 g (0.5 mmol)
p-Diiodobenzene: 0.165 g (0.5 mmol)
Palladium diacetate: 2.3 mg (0.01 mmol)
1,3-Bis (diphenylphosphino) propane: 8.3 mg (0.02 mmol)
N, N-dimethylaminopyridine: 0.916 mL (5.35 mmol)
Dimethyl sulfoxide: 2.5 mL (35.2 mmol)
(2) After completion of the reaction, the mixture was poured into 40 mL of 1N hydrochloric acid and extracted three times with 30 mL of dichloromethane.

(3) The organic layer was washed 3 times with 20 mL of 6N hydrochloric acid and 30 mL of water.

(4) The extract was dried over magnesium sulfate and concentrated under reduced pressure. The weight of the residue after concentration is shown in the column of weight A in Table 1.

(5) The obtained residue was dissolved in 2 mL of dichloromethane, and the solution was added dropwise while stirring 50 mL of cyclohexane and reprecipitated. The weight obtained by reprecipitation is shown in the column of weight B in Table 1, and the yield is shown in column X of Table 1.

The molecular weight of the obtained precipitate was measured by GPC.

The polymer obtained by reprecipitation was purified as follows and used as a device evaluation sample.

(1) Washed with toluene using Soxhlet extractor for 2-4 days.

(2) Using column chromatography (silica gel (K-60N, manufactured by Kanto Chemical Co., Inc.)), first subject the column to chromatography with a dichloromethane solution of the polymer, wash impurities with a 5% methanol-dichloromethane solution, and wash the polymer with methanol. Elute. The obtained polymer solution was purified by removing the solvent under reduced pressure or by reprecipitation and washing.

The obtained element evaluation sample was measured by NMR and IR.
¹ H NMR (60 MHz, CDCl3) d1.43 (s br, 6H, CH ₃ ), 7.27-8.02 (m, 20H, Ar-H)
IR (KBr) u 3402, 2919, 1598, 1438, 1182, 1113, 1002, 692, 554 cm ^-1

* Weight average molecular weight Mw and number average molecular weight Mn were calculated based on polystyrene using Shodex GPC K-804L manufactured by Showa Denko. In GPC, detection was performed at a wavelength of 254 nm using a 0.5% triethylamine-chloroform solution at a flow rate of 1.0 mL / min.
* Yield X was calculated based on the molecular weight per repeating structure (516).

3-2
The polymerization reaction was performed as follows under conditions different from those described in 3-1.

2,7-bis (phenylphosphinoyl) -9,9-dimethylfluorene 265 mg (0.6 mmol), 1,4-diiodobenzene 165 mg (0.5 mmol), palladium acetate 2.3 mg (0.01 mmol), 1,3 8.2 mg (0.02 mmol) of-(diphenylphosphinoyl) propane and 0.93 mL of diisopropylethylamine were dissolved in 2.5 mL of 1-methyl-2-pyrrolidone, and degassed at -80 ° C. Thereafter, a balloon filled with argon was attached, and the mixture was stirred at 100 ° C. for 24 hours. After completion of the reaction, the reaction solution was dissolved in 100 mL of 1N hydrochloric acid and extracted three times with 100 mL of dichloromethane. The organic layer was washed 3 times with 100 mL of water, dried over magnesium sulfate, and concentrated under reduced pressure. The obtained concentrate was dissolved in 4 mL of THF and 5 mL of dichloromethane and poured into cyclohexane. The resulting precipitate was collected by filtration under reduced pressure to obtain 314 mg of a white solid.

As a result of measuring the molecular weight of this white solid by GPC (pSt standard), Mw で 6307 and Mn 2681 were obtained.

In the reprecipitation, an attempt was made to dissolve the polymer using THF, which is considered to be easily dispersed in cyclohexane. However, since the compound was difficult to dissolve, dichloromethane was further added and dissolved.

291 mg of the obtained solid was added to a cylindrical filter paper, and extraction was performed by refluxing with 80 mL of toluene for 15 hours using a Soxhlet extractor. The obtained filtrate was concentrated to obtain 22 mg of yellow oil.

As a result of measuring the molecular weight of this oily substance by GPC (pSt standard), Mw1821 and Mn 858 were obtained.

Next, an example of a method for synthesizing the polymer compound represented by the structural formula (6) will be described with reference to FIG.

1. Synthesis of 5,5′-bis (phenylphosphinoyl) -2,2′-bithiophene In a nitrogen atmosphere at −80 ° C., a THF solution containing 3.00 g (18 mmol) of 2,2′-bithiophene . 25 mL (40 mmol) of 6M n-butyllithium hexane solution was added over 10 minutes.

After stirring at −80 ° C. for 30 minutes, the mixture was stirred at room temperature for 2 hours.

The mixture was cooled again to −80 ° C., 9.32 g (43.2 mmol) of chloro (diethylamino) phenylphosphine was added, and the mixture was stirred at −80 ° C. for 1 hour and at room temperature for 5.5 hours.

To this solution, 22.5 mL (270 mmol) of 12N hydrochloric acid was added and stirred at room temperature for 12 hours.

Water 100 mL was added, neutralized with sodium bicarbonate, and extracted with dichloromethane.

The organic layer was dried with magnesium sulfate, and the solvent was removed under reduced pressure. The obtained residue was purified by column chromatography (silica gel, developing solvent: dichloromethane: methanol = 100: 2), and 3.26 g of 5,5′-bis (phenylphosphinoyl) -2,2′-bithiophene was obtained. Obtained as a yellow oil (44% yield).

The resulting product (monomer) was identified by measuring with MS and NMR.
MS (FAB +, 3-nitrobenzyl alcohol) m / z 415 (M + H)
¹ H NMR (CDCl ₃ , 60 Hz) d4.68 (d, 2H, 1J = 73.4 Hz, PH), d 7.27-8.01 (m, 14H)
2. Polymerization of 5,5'-bis (phenylphosphinoyl) -2,2'-bithiophene with 1,4-diiodobenzene 5,5'-bis (phenylphosphinoyl) -2,2'-bithiophene 414 mg (1 mmol), 1,4-diiodobenzene 330 mg (1 mmol), palladium acetate 4.5 mg (0.02 mmol), 1,3-bisdiphenylphosphinopropane 16.5 mg (0.04 mmol) and dimethylaminopyridine 1.31 g (10.7 mmol) was dissolved in 5 mL of dimethylacetamide and reacted at 100 ° C. for 4 days.

After completion of the reaction, the mixture was poured into 1N hydrochloric acid and extracted with dichloromethane.

The organic layer was dried with magnesium sulfate, and the solvent was removed under reduced pressure.

The obtained residue was dissolved in 5 mL of dichloromethane and poured into 50 mL of cyclohexane for reprecipitation. The precipitate was collected by filtration and then dried under reduced pressure to obtain 446 mg of polymer (recovery rate 91%).

The obtained polymer was washed with toluene for 2 days using a Soxhlet extractor. The obtained residue was dissolved in dichloromethane, subjected to column chromatography (silica gel), washed with 5% methanol-dichloromethane solution and eluted with 50% methanol-dichloromethane solution. The solvent of the obtained solution was removed under reduced pressure to obtain 236 mg of a polymer.

About the obtained polymer, the measurement of the weight average molecular weight Mw, the number average molecular weight Mn, and the NMR measurement were performed.
Mw 4703, Mn 1279 (pSt standard)
1H NMR (60MHz, CDCl ₃ ) d7.28-7.83 (m, 16H)
[Characteristics and effects of the above synthesis method]
In the synthesis methods shown in FIGS. 9 and 10, in the monomer synthesis step, chloro (diethylamino) phenylphosphine is used and reacted with M-Ar-M (Ar is an aromatic residue, M is a metal). Thus, the target monomer can be synthesized while suppressing side reactions, and the reaction efficiency can be increased.

That is, when a phosphine compound having a plurality of sites that react with Ar-M, such as dichlorophenylphosphine, is used, it crosslinks with P -Ar-P-Ar-P and is easily polymerized as shown in Chemical Formula 19 below.

In contrast, chloro (diethylamino) phenylphosphine has only one site that reacts with Ar-M. Therefore, when reacted with M-Ar-M, a monomer is synthesized while suppressing polymerization, as shown in Chemical Formula 20 below. it can.

As described above, the synthesis method is shown for the polymer compounds represented by the structural formulas (3) and (6), but the polymer compounds represented by the general structural formulas (1) and (2) are also synthesized by the same method. be able to.

[Performance comparison of organic EL elements]
The usefulness of the present invention will be considered by fabricating organic EL elements according to Example 1 and Comparative Examples 1 and 2 and comparing the performances thereof.

Example 1
FIG. 5 is a schematic cross-sectional view illustrating the configuration of the organic EL element according to Example 1.

A non-alkali glass made of Matsunami glass is used as the substrate 101. On the surface of the substrate 101, the cathode 102, the electron transport layer 104, the light emitting layer 105, the hole transport layer 106, the hole injection layer 107, The anode 108 was formed in order.

The cathode 102 is formed by depositing ITO on the surface of the substrate 101 with a thickness of 50 nm by a sputtering method, patterning the ITO film by etching using a photolithography method using a photosensitive resist, and peeling the photosensitive resist. did. Subsequently, the substrate was cleaned using a neutral detergent and pure water, and then UV ozone cleaning was performed.

The electron injection layer 104 is prepared by applying a solution obtained by mixing lithium acetylacetate to the polymer compound of the structural formula (3) at 10 wt% and dissolving in ethanol by spin coating, and baking at 130 ° C. in nitrogen. Formed by. The rotation speed of the spin coat was 5000 rpm. The thickness of the electron injection layer 104 after baking was 20 nm.

The light emitting layer 105 was formed by using a super yellow of Merck as a light emitting material, spin-coating a solution obtained by dissolving this in 4-methoxytoluene, and baking at 130 ° C. The thickness of the light emitting layer 105 after baking was 50 nm.

The hole transport layer 106 was formed of diphenylnaphthyldiamine (NPD, manufactured by Nippon Steel Chemical Co., Ltd.) with a film thickness of 60 nm by a vacuum deposition method.

The hole injection layer 107 was formed of molybdenum oxide (MoOx high purity chemical) with a film thickness of 20 nm by vacuum deposition. Finally, as the anode 108, aluminum (high purity chemical purity 99.9%) was formed into a thin film with a film thickness of 80 nm by a vacuum deposition method, and an organic EL device according to Example 1 was manufactured.

Although not shown in FIG. 5, the produced organic EL device was sealed in a glass can in a nitrogen dry box having a water and oxygen concentration of 5 ppm or less so that the organic EL device could be evaluated in the air. .

(Comparative Example 1)
An organic EL device according to Comparative Example 1 was produced in the same manner as in Example 1 except that the electron transport layer 104 was not formed.

(Comparative Example 2)
An anode is formed of ITO on the surface of the substrate 101 similar to that of the first embodiment, PEDOT: PSS is formed with a film thickness of 70 nm as a hole injection layer, and a light emitting layer is stacked thereon as in the first embodiment. Then, barium (Ba Aldrich) having a film thickness of 5 nm was formed as an electron injection layer by a vacuum evaporation method, and aluminum similar to that in Example 1 was stacked with a film thickness of 80 nm as a cathode, whereby organic EL according to Comparative Example 2 was used. An element was produced.

The performance of the organic EL device of Example 1 and the organic EL devices of Comparative Examples 1 and 2 produced in this manner was evaluated as follows.

While changing the voltage between the anode and the cathode from −3.5 V to 11 V in increments of 0.25 V, the current, luminance, and chromaticity flowing between the anode and the cathode were measured. Moreover, the luminous efficiency was calculated from the measurement results.

The evaluation device used Keythley 2400 as a voltage source and an ammeter.

Otsuka Electronics MC-940 was used as a luminance meter.

Table 2 shows the measurement results when the applied voltage was 9V.

From the results in Table 2, it can be seen that the organic EL device of Example 1 has good luminance and light emission efficiency, but does not emit light well when the electron transport layer 104 is eliminated as in Comparative Example 1.

Further, as in Comparative Example 2, when the positive electrode, the hole injection layer made of PEDOT: PSS, and the light emitting layer are formed in this order, the luminance and the light emission efficiency are good, but the inverted structure is not used.

<Modifications>
In the above embodiment, the electron injection layer 104 is formed by a wet method in which an ink in which a polymer compound having an organic phosphine oxide skeleton is dissolved in a solvent is applied. However, the method for forming the electron injection layer 104 is not necessarily a wet method. Alternatively, the electron injection layer 104 may be formed by forming a thin film of a polymer compound having an organic phosphine oxide skeleton. In this case, the light emitting layer 105 is formed by a wet process using a nonpolar solvent on the electron injection layer 104. Since the polymer compound constituting the electron injection layer 104 is not dissolved in the nonpolar solvent when the film is formed, the same effect can be obtained.

In the above embodiment, the electron injection layer 104 is formed of a polymer compound having an organic phosphine oxide skeleton, and the light emitting layer 105 is formed thereon by dissolving the material in a nonpolar solvent by a wet method. After the electron injection layer 104 is formed of a polymer compound having a skeleton, an electron transport layer or a hole blocking layer is formed by a wet method using a nonpolar solvent instead of the light emitting layer, and a light emitting layer is formed thereon. You may laminate.

In this case, an ink in which an organic material for forming an electron transport layer or a hole blocking layer is dissolved in a nonpolar solvent is applied to form these layers. The polymer compound constituting the electron injection layer 104 is used as a nonpolar solvent. Since it does not dissolve, it has the same effect.

The hole blocking layer is made of a hole blocking material that has a function of transporting electrons but has a very small ability to transport holes, and improves the recombination probability of electrons and holes by blocking holes. .

In this case, examples of the material for the electron transport layer and the hole blocking layer include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyrandioxide derivatives, carbodiimides, fluorenylidenemethane derivatives, anthraquinodimethane and anthrone derivatives. And oxadiazole derivatives. In addition, thiadiazole derivatives in which the oxygen atom of the oxadiazole ring in the oxadiazole derivative is substituted with a sulfur atom, and quinoxaline derivatives having a quinoxaline ring known as an electron-withdrawing group can also be used as an electron transport material. In addition, a polymer material in which these materials are introduced into a polymer chain, or a polymer material having these materials as a main chain can also be used.

The organic EL element described in the above embodiment is a bottom mission type, and the direction in which light is extracted from the organic EL element is the substrate side, but is the top emission type in which light is extracted from the side opposite to the substrate side. You can also Alternatively, light can be extracted from both the substrate side and the opposite side of the substrate.

In the above embodiment, an example in which the organic EL element of the present invention is applied to an organic EL display device has been described. However, the organic EL element according to the present invention can also be applied to an organic EL lighting device.

The polymer compound according to the present invention can be used as a material for forming an electron injection layer or an electron transport layer of an organic EL device, and particularly for forming an electron injection layer or an electron transport layer of an organic EL device having an inverted structure. Is suitable. The organic EL element can be applied to, for example, a display device or a lighting device for a mobile phone or a television, and can be used as a display device or a lighting device having good light emission characteristics.

DESCRIPTION OF SYMBOLS 100 Display panel 101 Substrate 102 Cathode 103 Bank 104 Electron injection layer 105 Light emitting layer 106 Hole transport layer 107 Hole injection layer 108 Anode 110 Organic EL element

Claims (5)

1. A polymer compound represented by the general structural formula (1).
   

   

   Here, in the formula (1), Ar 1 and Ar 2 are monovalent aromatic residues which may be the same or different from each other, and Ar 3 and Ar 4 may be the same or different from each other 2 Valent aromatic residue. n is a natural number of 2 or more.
2. A polymer compound represented by the general structural formula (2).
   

   

   Here, in the formula (2), Ar 1 and Ar 2 are aromatic residues which may be the same or different from each other, and R 1 and R 2 may be the same or different from each other. An aliphatic substituent. n is a natural number of 2 or more.
3. The polymer compound according to claim 2 represented by Structural Formula (3).
   

   

   Here, in Formula (3), n is a natural number of 2 or more.
4. The weight average molecular weight is 2000 or more,
   The polymer compound according to any one of claims 1 to 3.
5. A method for producing the polymer compound according to claim 1, comprising:
   A method for producing a polymer compound comprising a polymerization step in which a compound represented by the general structural formula (4) and a compound of the general formula (5) are condensed in a solvent in the presence of a condensation catalyst and a base, and polymerized.
   

   

   In the formulas (4) and (5), Ar 1 and Ar 2 are monovalent aromatic residues which may be the same or different from each other, and Ar 3 and Ar 4 are the same or different from each other. It is a good divalent aromatic residue. A part of the hydrogen atoms of Ar1 to Ar4 may be substituted with an alkyl group, an aromatic residue, or a diarylphosphinoyl group. X is a halogen atom selected from iodine, bromine and chlorine.

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